mud pump 3d model made in china

This is a basic mud pump used on a common drill site as part of the mud system, the model itself is pretty basic, 1 piece and no materials. looks great on a drill site animation!

A pump is a device that moves fluids (liquids or gases), or sometimes slurries, by mechanical action. Pumps can be classified into three major groups according to the method they use to move the fluid: direct lift, displacement, and gravity pumps.

Pumps operate by some mechanism (typically reciprocating or rotary), and consume energy to perform mechanical work by moving the fluid. Pumps operate via many energy sources, including manual operation, electricity, engines, or wind power, come in many sizes, from microscopic for use in medical applications to large industrial pumps.

Mechanical pumps serve in a wide range of applications such as pumping water from wells, aquarium filtering, pond filtering and aeration, in the car industry for water-cooling and fuel injection, in the energy industry for pumping oil and natural gas or for operating cooling towers. In the medical industry, pumps are used for biochemical processes in developing and manufacturing medicine, and as artificial replacements for body parts, in particular the artificial heart and penile prosthesis.

In biology, many different types of chemical and bio-mechanical pumps have evolved, and biomimicry is sometimes used in developing new types of mechanical pumps.

Pumps can be classified by their method of displacement into positive displacement pumps, impulse pumps, velocity pumps, gravity pumps, steam pumps and valveless pumps. There are two basic types of pumps: positive displacement and centrifugal. Although axial-flow pumps are frequently classified as a separate type, they have essentially the same operating principles as centrifugal pumps.

Some positive displacement pumps use an expanding cavity on the suction side and a decreasing cavity on the discharge side. Liquid flows into the pump as the cavity on the suction side expands and the liquid flows out of the discharge as the cavity collapses. The volume is constant through each cycle of operation.

Positive displacement pumps, unlike centrifugal or roto-dynamic pumps, theoretically can produce the same flow at a given speed (RPM) no matter what the discharge pressure. Thus, positive displacement pumps are constant flow machines. However, a slight increase in internal leakage as the pressure increases prevents a truly constant flow rate. in case.

A positive displacement pump must not operate against a closed valve on the discharge side of the pump, because it has no shutoff head like centrifugal pumps. A positive displacement pump operating against a closed discharge valve continues to produce flow and the pressure in the discharge line increases until the line bursts, the pump is severely damaged, or both.

A relief or safety valve on the discharge side of the positive displacement pump is therefore necessary. The relief valve can be internal or external. The pump manufacturer normally has the option to supply internal relief or safety valves. The internal valve is usually only used as a safety precaution. An external relief valve in the discharge line, with a return line back to the suction line or supply tank provides increased safety.

Rotary-type positive displacement: internal gear, screw, shuttle block, flexible vane or sliding vane, circumferential piston, flexible impeller, helical twisted roots (e.g. the Wendelkolben pump) or liquid-ring pumps

Drawbacks: The nature of the pump requires very close clearances between the rotating pump and the outer edge, making it rotate at a slow, steady speed. If rotary pumps are operated at high speeds, the fluids cause erosion, which eventually causes enlarged clearances that liquid can pass through, which reduces efficiency.

Rotary vane pumps – similar to scroll compressors, these have a cylindrical rotor encased in a similarly shaped housing. As the rotor orbits, the vanes trap fluid between the rotor and the casing, drawing the fluid through the pump.

Reciprocating pumps move the fluid using one or more oscillating pistons, plungers, or membranes (diaphragms), while valves restrict fluid motion to the desired direction.

Pumps in this category range from simplex, with one cylinder, to in some cases quad (four) cylinders, or more. Many reciprocating-type pumps are duplex (two) or triplex (three) cylinder. They can be either single-acting with suction during one direction of piston motion and discharge on the other, or double-acting with suction and discharge in both directions. The pumps can be powered manually, by air or steam, or by a belt driven by an engine. This type of pump was used extensively in the 19th century—in the early days of steam propulsion—as boiler feed water pumps. Now reciprocating pumps typically pump highly viscous fluids like concrete and heavy oils, and serve in special applications that demand low flow rates against high resistance. Reciprocating hand pumps were widely used to pump water from wells. Common bicycle pumps and foot pumps for inflation use reciprocating action.

These positive displacement pumps have an expanding cavity on the suction side and a decreasing cavity on the discharge side. Liquid flows into the pumps as the cavity on the suction side expands and the liquid flows out of the discharge as the cavity collapses. The volume is constant given each cycle of operation.

This is the simplest of rotary positive displacement pumps. It consists of two meshed gears that rotate in a closely fitted casing. The tooth spaces trap fluid and force it around the outer periphery. The fluid does not travel back on the meshed part, because the teeth mesh closely in the center. Gear pumps see wide use in car engine oil pumps and in various hydraulic power packs.

A screw pump is a more complicated type of rotary pump that uses two or three screws with opposing thread — e.g., one screw turns clockwise and the other counterclockwise. The screws are mounted on parallel shafts that have gears that mesh so the shafts turn together and everything stays in place. The screws turn on the shafts and drive fluid through the pump. As with other forms of rotary pumps, the clearance between moving parts and the pump"s casing is minimal.

Widely used for pumping difficult materials, such as sewage sludge contaminated with large particles, this pump consists of a helical rotor, about ten times as long as its width. This can be visualized as a central core of diameter x with, typically, a curved spiral wound around of thickness half x, though in reality it is manufactured in single casting. This shaft fits inside a heavy duty rubber sleeve, of wall thickness also typically x. As the shaft rotates, the rotor gradually forces fluid up the rubber sleeve. Such pumps can develop very high pressure at low volumes.

Named after the Roots brothers who invented it, this lobe pump displaces the liquid trapped between two long helical rotors, each fitted into the other when perpendicular at 90°, rotating inside a triangular shaped sealing line configuration, both at the point of suction and at the point of discharge. This design produces a continuous flow with equal volume and no vortex. It can work at low pulsation rates, and offers gentle performance that some applications require.

A peristaltic pump is a type of positive displacement pump. It contains fluid within a flexible tube fitted inside a circular pump casing (though linear peristaltic pumps have been made). A number of rollers, shoes, or wipers attached to a rotor compresses the flexible tube. As the rotor turns, the part of the tube under compression closes (or occludes), forcing the fluid through the tube. Additionally, when the tube opens to its natural state after the passing of the cam it draws (restitution) fluid into the pump. This process is called peristalsis and is used in many biological systems such as the gastrointestinal tract.

Efficiency and common problems: With only one cylinder in plunger pumps, the fluid flow varies between maximum flow when the plunger moves through the middle positions, and zero flow when the plunger is at the end positions. A lot of energy is wasted when the fluid is accelerated in the piping system. Vibration and

Triplex plunger pumps use three plungers, which reduces the pulsation of single reciprocating plunger pumps. Adding a pulsation dampener on the pump outlet can further smooth the pump ripple, or ripple graph of a pump transducer. The dynamic relationship of the high-pressure fluid and plunger generally requires high-quality plunger seals. Plunger pumps with a larger number of plungers have the benefit of increased flow, or smoother flow without a pulsation dampener. The increase in moving parts and crankshaft load is one drawback.

Car washes often use these triplex-style plunger pumps (perhaps without pulsation dampeners). In 1968, William Bruggeman significantly reduced the size of the triplex pump and increased the lifespan so that car washes could use equipment with smaller footprints. Durable high pressure seals, low pressure seals and oil seals, hardened crankshafts, hardened connecting rods, thick ceramic plungers and heavier duty ball and roller bearings improve reliability in triplex pumps. Triplex pumps now are in a myriad of markets across the world.

Triplex pumps with shorter lifetimes are commonplace to the home user. A person who uses a home pressure washer for 10 hours a year may be satisfied with a pump that lasts 100 hours between rebuilds. Industrial-grade or continuous duty triplex pumps on the other end of the quality spectrum may run for as much as 2,080 hours a year.

The oil and gas drilling industry uses massive semi trailer-transported triplex pumps called mud pumps to pump drilling mud, which cools the drill bit and carries the cuttings back to the surface.

One modern application of positive displacement pumps is compressed-air-powered double-diaphragm pumps. Run on compressed air these pumps are intrinsically safe by design, although all manufacturers offer ATEX certified models to comply with industry regulation. These pumps are relatively inexpensive and can perform a wide variety of duties, from pumping water out of bunds, to pumping hydrochloric acid from secure storage (dependent on how the pump is manufactured – elastomers / body construction). Lift is normally limited to roughly 6m although heads can reach almost 200 psi (1.4 MPa).

Devised in China as chain pumps over 1000 years ago, these pumps can be made from very simple materials: A rope, a wheel and a PVC pipe are sufficient to make a simple rope pump. Rope pump efficiency has been studied by grass roots organizations and the techniques for making and running them have been continuously improved.

Impulse pumps use pressure created by gas (usually air). In some impulse pumps the gas trapped in the liquid (usually water), is released and accumulated somewhere in the pump, creating a pressure that can push part of the liquid upwards.

Instead of a gas accumulation and releasing cycle, the pressure can be created by burning of hydrocarbons. Such combustion driven pumps directly transmit the impulse form a combustion event through the actuation membrane to the pump fluid. In order to allow this direct transmission, the pump needs to be almost entirely made of an elastomer (e.g. silicone rubber). Hence, the combustion causes the membrane to expand and thereby pumps the fluid out of the adjacent pumping chamber. The first combustion-driven soft pump was developed by ETH Zurich.

It takes in water at relatively low pressure and high flow-rate and outputs water at a higher hydraulic-head and lower flow-rate. The device uses the water hammer effect to develop pressure that lifts a portion of the input water that powers the pump to a point higher than where the water started.

The hydraulic ram is sometimes used in remote areas, where there is both a source of low-head hydropower, and a need for pumping water to a destination higher in elevation than the source. In this situation, the ram is often useful, since it requires no outside source of power other than the kinetic energy of flowing water.

Rotodynamic pumps (or dynamic pumps) are a type of velocity pump in which kinetic energy is added to the fluid by increasing the flow velocity. This increase in energy is converted to a gain in potential energy (pressure) when the velocity is reduced prior to or as the flow exits the pump into the discharge pipe. This conversion of kinetic energy to pressure is explained by the

A practical difference between dynamic and positive displacement pumps is how they operate under closed valve conditions. Positive displacement pumps physically displace fluid, so closing a valve downstream of a positive displacement pump produces a continual pressure build up that can cause mechanical failure of pipeline or pump. Dynamic pumps differ in that they can be safely operated under closed valve conditions (for short periods of time).

Such a pump is also referred to as a centrifugal pump. The fluid enters along the axis or center, is accelerated by the impeller and exits at right angles to the shaft (radially); an example is the centrifugal fan, which is commonly used to implement a vacuum cleaner. Generally, a radial-flow pump operates at higher pressures and lower flow rates than an axial- or a mixed-flow pump.

These are also referred to as All fluid pumps. The fluid is pushed outward or inward and move fluid axially. They operate at much lower pressures and higher flow rates than radial-flow (centripetal) pumps.

Mixed-flow pumps function as a compromise between radial and axial-flow pumps. The fluid experiences both radial acceleration and lift and exits the impeller somewhere between 0 and 90 degrees from the axial direction. As a consequence mixed-flow pumps operate at higher pressures than axial-flow pumps while delivering higher discharges than radial-flow pumps. The exit angle of the flow dictates the pressure head-discharge characteristic in relation to radial and mixed-flow.

Steam pumps have been for a long time mainly of historical interest. They include any type of pump powered by a steam engine and also pistonless pumps such as Thomas Savery"s or the Pulsometer steam pump.

Recently there has been a resurgence of interest in low power solar steam pumps for use in smallholder irrigation in developing countries. Previously small steam engines have not been viable because of escalating inefficiencies as vapour engines decrease in size. However the use of modern engineering materials coupled with alternative engine configurations has meant that these types of system are now a cost effective opportunity.

Valveless pumping assists in fluid transport in various biomedical and engineering systems. In a valveless pumping system, no valves (or physical occlusions) are present to regulate the flow direction. The fluid pumping efficiency of a valveless system, however, is not necessarily lower than that having valves. In fact, many fluid-dynamical systems in nature and engineering more or less rely upon valveless pumping to transport the working fluids therein. For instance, blood circulation in the cardiovascular system is maintained to some extent even when the heart’s valves fail. Meanwhile, the embryonic vertebrate heart begins pumping blood long before the development of discernible chambers and valves. In microfluidics, valveless impedance pumps have been fabricated, and are expected to be particularly suitable for handling sensitive biofluids. Ink jet printers operating on the Piezoelectric transducer principle also use valveless pumping. The pump chamber is emptied through the printing jet due to reduced flow impedance in that direction and refilled by capillary action..

Examining pump repair records and mean time between failures (MTBF) is of great importance to responsible and conscientious pump users. In view of that fact, the preface to the 2006 Pump User’s Handbook alludes to "pump failure" statistics. For the sake of convenience, these failure statistics often are translated into MTBF (in this case, installed life before failure).

In early 2005, Gordon Buck, John Crane Inc.’s chief engineer for Field Operations in Baton Rouge, LA, examined the repair records for a number of refinery and chemical plants to obtain meaningful reliability data for centrifugal pumps. A total of 15 operating plants having nearly 15,000 pumps were included in the survey. The smallest of these plants had about 100 pumps; several plants had over 2000. All facilities were located in the United States. In addition, considered as "new", others as "renewed" and still others as "established". Many of these plants—but not all—had an alliance arrangement with John Crane. In some cases, the alliance contract included having a John Crane Inc. technician or engineer on-site to coordinate various aspects of the program.

Not all plants are refineries, however, and different results occur elsewhere. In chemical plants, pumps have traditionally been "throw-away" items as chemical attack limits life. Things have improved in recent years, but the somewhat restricted space available in "old" DIN and ASME-standardized stuffing boxes places limits on the type of seal that fits. Unless the pump user upgrades the seal chamber, the pump only accommodates more compact and simple versions. Without this upgrading, lifetimes in chemical installations are generally around 50 to 60 percent of the refinery values.

Unscheduled maintenance is often one of the most significant costs of ownership, and failures of mechanical seals and bearings are among the major causes. Keep in mind the potential value of selecting pumps that cost more initially, but last much longer between repairs. The MTBF of a better pump may be one to four years longer than that of its non-upgraded counterpart. Consider that published average values of avoided pump failures range from US$2600 to US$12,000. This does not include lost opportunity costs. One pump fire occurs per 1000 failures. Having fewer pump failures means having fewer destructive pump fires.

As has been noted, a typical pump failure based on actual year 2002 reports, costs US$5,000 on average. This includes costs for material, parts, labor and overhead. Extending a pump"s MTBF from 12 to 18 months would save US$1,667 per year — which might be greater than the cost to upgrade the centrifugal pump"s reliability.

Pumps are used throughout society for a variety of purposes. Early applications includes the use of the windmill or watermill to pump water. Today, the pump is used for irrigation, water supply, gasoline supply, air conditioning systems, refrigeration (usually called a compressor), chemical movement, sewage movement, flood control, marine services, etc.

Because of the wide variety of applications, pumps have a plethora of shapes and sizes: from very large to very small, from handling gas to handling liquid, from high pressure to low pressure, and from high volume to low volume.

Typically, a liquid pump can"t simply draw air. The feed line of the pump and the internal body surrounding the pumping mechanism must first be filled with the liquid that requires pumping: An operator must introduce liquid into the system to initiate the pumping. This is called priming the pump. Loss of prime is usually due to ingestion of air into the pump. The clearances and displacement ratios in pumps for liquids, whether thin or more viscous, usually cannot displace air due to its compressibility. This is the case with most velocity (rotodynamic) pumps — for example, centrifugal pumps.

Positive–displacement pumps, however, tend to have sufficiently tight sealing between the moving parts and the casing or housing of the pump that they can be described as self-priming. Such pumps can also serve as priming pumps, so called when they are used to fulfill that need for other pumps in lieu of action taken by a human operator.

One sort of pump once common worldwide was a hand-powered water pump, or "pitcher pump". It was commonly installed over community water wells in the days before piped water supplies.

In parts of the British Isles, it was often called the parish pump. Though such community pumps are no longer common, people still used the expression parish pump to describe a place or forum where matters of local interest are discussed.

Because water from pitcher pumps is drawn directly from the soil, it is more prone to contamination. If such water is not filtered and purified, consumption of it might lead to gastrointestinal or other water-borne diseases. A notorious case is the 1854 Broad Street cholera outbreak. At the time it was not known how cholera was transmitted, but physician John Snow suspected contaminated water and had the handle of the public pump he suspected removed; the outbreak then subsided.

Modern hand-operated community pumps are considered the most sustainable low-cost option for safe water supply in resource-poor settings, often in rural areas in developing countries. A hand pump opens access to deeper groundwater that is often not polluted and also improves the safety of a well by protecting the water source from contaminated buckets. Pumps such as the Afridev pump are designed to be cheap to build and install, and easy to maintain with simple parts. However, scarcity of spare parts for these type of pumps in some regions of Africa has diminished their utility for these areas.

Multiphase pumping applications, also referred to as tri-phase, have grown due to increased oil drilling activity. In addition, the economics of multiphase production is attractive to upstream operations as it leads to simpler, smaller in-field installations, reduced equipment costs and improved production rates. In essence, the multiphase pump can accommodate all fluid stream properties with one piece of equipment, which has a smaller footprint. Often, two smaller multiphase pumps are installed in series rather than having just one massive pump.

For midstream and upstream operations, multiphase pumps can be located onshore or offshore and can be connected to single or multiple wellheads. Basically, multiphase pumps are used to transport the untreated flow stream produced from oil wells to downstream processes or gathering facilities. This means that the pump may handle a flow stream (well stream) from 100 percent gas to 100 percent liquid and every imaginable combination in between. The flow stream can also contain abrasives such as sand and dirt. Multiphase pumps are designed to operate under changing or fluctuating process conditions. Multiphase pumping also helps eliminate emissions of greenhouse gases as operators strive to minimize the flaring of gas and the venting of tanks where possible.

A rotodynamic pump with one single shaft that requires two mechanical seals, this pump uses an open-type axial impeller. It"s often called a Poseidon pump, and can be described as a cross between an axial compressor and a centrifugal pump.

The twin-screw pump is constructed of two inter-meshing screws that move the pumped fluid. Twin screw pumps are often used when pumping conditions contain high gas volume fractions and fluctuating inlet conditions. Four mechanical seals are required to seal the two shafts.

Progressive cavity pumps are single-screw types typically used in shallow wells or at the surface. This pump is mainly used on surface applications where the pumped fluid may contain a considerable amount of solids such as sand and dirt.

These pumps are basically multistage centrifugal pumps and are widely used in oil well applications as a method for artificial lift. These pumps are usually specified when the pumped fluid is mainly liquid.

A buffer tank is often installed upstream of the pump suction nozzle in case of a slug flow. The buffer tank breaks the energy of the liquid slug, smooths any fluctuations in the incoming flow and acts as a sand trap.

As the name indicates, multiphase pumps and their mechanical seals can encounter a large variation in service conditions such as changing process fluid composition, temperature variations, high and low operating pressures and exposure to abrasive/erosive media. The challenge is selecting the appropriate mechanical seal arrangement and support system to ensure maximized seal life and its overall effectiveness.

From an initial design point of view, engineers often use a quantity termed the specific speed to identify the most suitable pump type for a particular combination of flow rate and head.

The power imparted into a fluid increases the energy of the fluid per unit volume. Thus the power relationship is between the conversion of the mechanical energy of the pump mechanism and the fluid elements within the pump. In general, this is governed by a series of simultaneous differential equations, known as the Navier–Stokes equations. However a more simple equation relating only the different energies in the fluid, known as Bernoulli"s equation can be used. Hence the power, P, required by the pump:

where Δp is the change in total pressure between the inlet and outlet (in Pa), and Q, the volume flow-rate of the fluid is given in m3/s. The total pressure may have gravitational, static pressure and kinetic energy components; i.e. energy is distributed between change in the fluid"s gravitational potential energy (going up or down hill), change in velocity, or change in static pressure. η is the pump efficiency, and may be given by the manufacturer"s information, such as in the form of a pump curve, and is typically derived from either fluid dynamics simulation (i.e. solutions to the Navier–Stokes for the particular pump geometry), or by testing. The efficiency of the pump depends upon the pump"s configuration and operating conditions (such as rotational speed, fluid density and viscosity etc.)

For a typical "pumping" configuration, the work is imparted on the fluid, and is thus positive. For the fluid imparting the work on the pump (i.e. a turbine), the work is negative. Power required to drive the pump is determined by dividing the output power by the pump efficiency. Furthermore, this definition encompasses pumps with no moving parts, such as a siphon.

Pump efficiency is defined as the ratio of the power imparted on the fluid by the pump in relation to the power supplied to drive the pump. Its value is not fixed for a given pump, efficiency is a function of the discharge and therefore also operating head. For centrifugal pumps, the efficiency tends to increase with flow rate up to a point midway through the operating range (peak efficiency or Best Efficiency Point (BEP) ) and then declines as flow rates rise further. Pump performance data such as this is usually supplied by the manufacturer before pump selection. Pump efficiencies tend to decline over time due to wear (e.g. increasing clearances as impellers reduce in size).

When a system includes a centrifugal pump, an important design issue is matching the head loss-flow characteristic with the pump so that it operates at or close to the point of its maximum efficiency.

C.M. Schumacher, M. Loepfe, R.Fuhrer, R.N. Grass, and W.J. Stark, "3D printed lost-wax casted soft silicone monoblocks enable heart-inspired pumping by internal combustion," RSC Advances, Vol. 4,pp. 16039–16042, 2014.

Wasser, Goodenberger, Jim and Bob (November 1993). "Extended Life, Zero Emissions Seal for Process Pumps". John Crane Technical Report. Routledge. TRP 28017.

Australian Pump Manufacturers" Association. Australian Pump Technical Handbook, 3rd edition. Canberra: Australian Pump Manufacturers" Association, 1987. ISBN 0-7316-7043-4.

Gear pumps are also widely used in chemical installations to pump high viscosity fluids. There are two main variations; external gear pumps which use two external spur gears, and internal gear pumps which use an external and an internal spur gears (internal spur gear teeth face inwards, see below). Gear pumps are positive displacement (or fixed displacement), meaning they pump a constant amount of fluid for each revolution. Some gear pumps are designed to function as either a motor or a pump.

As the gears rotate they separate on the intake side of the pump, creating a void and suction which is filled by fluid. The fluid is carried by the gears to the discharge side of the pump, where the meshing of the gears displaces the fluid. The mechanical clearances are small— in the order of 10 μm. The tight clearances, along with the speed of rotation, effectively prevent the fluid from leaking backwards.

Many variations exist, including; helical and herringbone gear sets (instead of spur gears), lobe shaped rotors similar to Roots blowers (commonly used as superchargers), and mechanical designs that allow the stacking of pumps. The most common variations are shown below (the drive gear is shown blue and the idler is shown purple).

An external precision gear pump is usually limited to a maximum working pressure of 210 bars (21,000 kPa) and a maximum speed of 3,000 rpm. Some manufacturers produce gear pumps with higher working pressures and speeds but these types of pumps tend to be noisy and special precautions may have to be made.

Suction and pressure ports need to interface where the gears mesh (shown as dim gray lines in the internal pump images). Some internal gear pumps have an additional, crescent-shaped seal (shown above, right).

Downloaded 3D Models can be used in 3ds Max, Blender, Maya, Lightwave, Softimage, Cinema 4D, Houdini, Daz Studio, Modo, Unity 3D, Unreal Engine, SketchUp, ZBrush, Poser and other 3D modeling software.

If you need, the following file formats can be exported from these above programs: 3D Studio (.3ds), Alembic (.abc), AutoCAD (.dxf, .dwg), COLLADA (.dae), Microsoft DirectX Direct3D (.x), glTF 2.0 WebGL (.glb, .gltf), Stanford (.ply), StereoLithography (.stl), Universal Scene Description (.usd, .usdc, .usda), VRML97 (.wrl), X3D Extensible 3D (.x3d).

Benshaw’s experience in the design, production and installation of mission critical motor controls and drives for continuous process industries is reflected in every product we build. Whether a rugged, reliable drive, a pump control panel or a motor control center, when it absolutely has to work, choose Benshaw.

Fuji Electric delivers high performance inverters that offer automatically controlled motor operations and operating speeds for a wide variety of AC drive/variable frequency drive (VFD) applications. The precision control of Fuji Electric inverters allows AC drives to operate at an optimal speed throughout your application, reducing overall power and energy consumption to minimize operating costs. Applications for these AC / VFD drive, and v/ Hz vector drive inverters include, conveyor systems, pumps, fans, and HVAC. Quality is our drive; World Class AC Drives.

Lafert NA is the sole North American representative for the Italian manufactured, Lafert IEC motor line, Sacemi Coolant Pumps and SITI metric line of gearboxes. Lafert NA is located in Mississauga, Ontario-Canada (Toronto) and has been supplying IEC metric motors to Canada, the United States and Mexico since 1989. In July 1998, Lafert NA received the sole North American distribution rights to the SITI line of Metric gear reducers, also produced in Italy. Lafert North America provides an extensive range of quality products at an outstanding service level. Replacing oddball foreign motors, that are sometimes costly to repair and difficult to source is one of Lafert North America’s specialties.

Baldor is pleased to offer the broadest range of industrial AC and DC electric motors to value-minded customers. Baldor-Reliance motors range from 1/50 through 15,000 HP, and we sell and support the entire line of ABB IEC motors and medium voltage motors up to 100,000 HP. Our Super-E motors are optimized for efficiency, ensuring the lowest operating costs for the customer. We also offer broad lines of brake-motors, explosion-proof, C-face, pump-motors and gear-motors to provide solutions for any purpose or environment. Baldor can offer custom motors to meet specific requirements. Custom motors are manufactured to the shortest lead times in the industry.

Techtop Industries is a privately owned and operated electric motor manufacturer. The home office is in Atlanta, Georgia, and the manufacturing facilities are in and around Shanghai. Techtop has been manufacturing electric motors as a private brand label manufacturer for many of the big name brands for almost 40 years for the European and Asian market. While we still manufacture some private label products, we are now more interested in developing our own brand recognition and equity through meticulous & very aggressive quality standards, strong distribution and OEM partners. Techtop stands behind our quality and value, offering warranties from 3 to a 5 years depending on the motor type. We manufacture and stock in one of our 20 distribution centers in the United States fractional to 300HP, true NEMA Premium motors, fractional to 110KW, IE3 IEC metric, fractional to 10HP, single phase, extra high torque farm & Ag duty, universal mount 56, crusher duty, IEEE841, JM & JP pump, Auger, design D high slip oil well pumping, inverter duty, cast iron and aluminum motors.

For over 100 years BROOK CROMPTON has been a leader in the development of high efficiency electric motors. Colonel Crompton, a pioneer in the development of DC motors, formed R.E.B. Crompton & Co in 1878 and Ernest Brook made his first AC motor in Huddersfield, UK in 1904 forming Brook Motors. The two organizations came together in the late 1960s and the company that is now BROOK CROMPTON has come a long way since then. BROOK CROMPTON is a leading provider of electric motors for the global industrial market, with motor solutions that benefit a wide range of customers involved in numerous diverse markets. Our products are used in almost every industrial activity including water treatment, building services, chemicals/petrochemicals, general processing and manufacturing where they drive fans, pumps, compressors and conveyors amongst other things.

With over 100 years of experience in motor design and application, TECO Westinghouse is a premier supplier of AC and DC motors and generators. Ranging from fractional HP ratings to 100,000 HP, these high-quality machines are used to drive pumps, fans, compressors, rolling mills, grinders, crushers, and a variety of other rugged applications. Our motors and generators are utilized in petroleum, chemical, pulp, paper, mining, marine propulsion, steel, electric utility and other industries throughout the world. The Westinghouse Motor Company was established in 1988 as a joint venture between Westinghouse Electric and TECO Electric and Machinery Co. Today, TWMC is in a unique position of being able to provide quality motors, generators, drives, and power solutions, all from our headquarters in Round Rock, Texas. This capability, combined with our global manufacturing resources, uniquely position the TECO-Westinghouse Motor Company to serve all our customer needs.

When North American Electric began in 1993 the product range consisted of Three Phase, TEFC, General Purpose, AC motors from 1 HP up to 150 HP. Our product range now includes NEMA Premium Efficient, Three Phase, TEFC, AC General Purpose Motors from 1/3 HP up to 600 HP and Single Phase, AC General Purpose Motors from 1/3 HP to 10 HP. In addition, our range now includes Special Purpose Motors such as Three Phase, TEFC NEMA Design D, Oil Well Pump Motors, Crusher Duty Motors, Vertical Hollow Shaft Motors, Compressor Duty Motors, Farm Duty Motors, Close Coupled Pump Motors, Stainless Steel Washdown Duty Motors, Shaft Mount Reducers and Motor Controls. Our company specializes in only sourcing products of the highest quality from manufacturers that meet the toughest industry standards and offer certifications such as UL, CSA, CE and ISO9001.

Benshaw’s experience in the design, production and installation of mission critical motor controls and drives for continuous process industries is reflected in every product we build. Whether a rugged, reliable drive, a pump control panel or a motor control center, when it absolutely has to work, choose Benshaw.

In order to study the evolution process, damage characteristics, and occurrence mechanism of water and mud inrush disaster in deep tunnel fault zone with infiltration instability under complex conditions, a set of the three-dimensional physical model test systems of water and mud inrush flow-solid coupling in tunnel fault zones is developed. The system mainly comprises a rigid test frame, ground stress loading system, hydraulic loading system, multiple information monitoring and acquisition system, and mud and water protrusion recovery system. The system’s main features are that it can meet the model’s simulation of the ground stress field, water pressure, and other complex environments subjected to ground stress, and water pressure gradients can be controlled. The system is characterized by high rigidity, high-pressure strength, visualization, good sealing, and expandability. Taking the water fault zone of a well in the Dazhu Mountain Tunnel of the Darui Railway as the research object, the new fault zone and surrounding rock similar materials applicable to the flow-solid coupling model test are designed using the self-developed flow-solid coupling similar materials. The system is used for model tests to reveal the spatial and temporal changes of the surrounding rock stress field and seepage field during the tunnel excavation process. The test results show that the system is stable and reliable, and the research method and results are of guiding significance to the research of the same type of underground engineering.

In recent years, China has developed into a country with the most significant number of tunnels and underground projects, the enormous scale, the most complex geological conditions, and the most diverse structural forms in the world [1–3]. More and more transportation infrastructure projects are shifting to the western mountainous and karst areas with a more complex topography and geological conditions. Tunnel construction faces new challenges, such as considerable buried depth, high ground stress, strong karst, high-water pressure, and complex structures [4–7], resulting in frequent disasters during the construction process. Statistics show that nearly 80% of traffic, water conservancy, and hydropower projects have experienced water and mud inrush disasters during the construction or operation. As a result, nearly 90% of the tunnels have been postponed or even forced to be suspended or rerouted, especially in areas with solid karst and high-water pressure; frequent geological disasters such as tunnel water bursting and mud bursting have brought great difficulties to construction, causing heavy casualties and economic losses [8–10].

Because of the main problems of high ground stress and high-water pressure in the construction of karst tunnels, it is essential to master the spatial and temporal changes of the surrounding rock stress field, displacement field, and seepage field during the tunnel excavation in such complex geological conditions to effectively prevent water and mud burst disasters and improve the stability of the tunnel surrounding rock. Due to the complexity of such tunnels’ surrounding rock structure and environment, we should adopt various means to study them as far as possible, and the main research methods are theoretical analysis, numerical calculation, and model test [11–17]. However, theoretical analysis has many limitations in dealing with nonlinear and discontinuous problems of complex rock masses. In contrast, numerical analysis methods cannot accurately portray the mechanical properties of the surrounding rock masses in terms of intrinsic model and calculation parameters selection and have inherent deficiencies in simulating the engineering response under complex conditions [18–20]. The geomechanical model test makes up for the shortage of theoretical analysis and numerical simulation. It can systematically and comprehensively reflect the characteristics of the surrounding rock and its spatial relationship with karst pipes and caves, more accurately simulate the tunnel excavation process, and visually reflect the physical and mechanical phenomena of the deep rock mass, which is a proven research tool [21, 22].

At present, the relevant research on geomechanical model test system device mainly includes the following: Zhu et al. [23] developed an extensive accurate triaxial loading geomechanical model test system, which can carry out horizontal lateral step load under entire triaxial stress state and successfully observe the fracture phenomenon and fracture process of surrounding rock of caverns with different large buried depths, which is helpful to the study of fracture mechanism; Zhang et al. [24] developed a model test system for water and mud inrush in fault fracture zone and studied the catastrophic evolution process and failure characteristics of water and mud inrush in tunnel during fault exposure; Li et al. [25–28] developed a new fluid-structure coupling model test system, which can be used for plane stress and plane strain model tests, and revealed the variation laws of surrounding rock displacement field, seepage field, and tunnel wall pressure during tunnel excavation; Li et al. [29, 30] developed a three-dimensional model test system for water inrush geological disasters in deep and long tunnels and obtained the minimum water separation safety thickness under different engineering conditions; Zhang [31] developed an ultrahigh-pressure 3D loading model test system with intelligent numerical control function, which revealed the collapse failure mode, nonlinear deformation characteristics, and stress change law of ancient karst cave formation. To sum up, there is a relative lack of geomechanical model tests related to water and mud inrush disasters in tunnels in fault fracture zones. There are mainly the following problems to be solved when using the above model test system to study water and mud inrush disasters in fault fracture zones: (1) The model size is small, it is impossible to carry out large-scale tests, and there is an apparent boundary effect. (2) Most of them focus on the stability of surrounding rock during tunnel excavation under the action of in situ stress, without considering the catastrophic evolution process of rock mass in fault fracture zone under the combined action of groundwater and excavation disturbance. (3) There are few studies on similar materials of filling medium in the fault fracture zone. At present, most of the fluid-solid coupling similar materials only consider physical indexes such as density and size, and few similar materials meet solid mechanical properties and permeability [32–35]. Less similar materials with different characteristics of surrounding rock and fault rock are applied to the same test simultaneously.

The test system of this study is mainly composed of a rigid test frame, in situ stress loading system, hydraulic loading system, multivariate information monitoring and acquisition system, and mud and water protrusions recovery system. The system’s main feature is that it can meet the model’s simulation of the complex environment such as in situ stress field and water pressure. The in situ stress and water pressure gradient are controllable. The system has significant stiffness, high bearing strength, visualization, good sealing, and strong expansibility. Taking the Yijingshui fracture zone of the Dazhu Mountain Tunnel of Darui railway as the research object, using the self-developed fluid-structure coupling similar material, a new fault fracture zone and surrounding rock that are suitable for fluid-structure coupling model test are designed in this paper. The system is used for model tests to reveal the surrounding rock stress field’s temporal and spatial variation laws and seepage field during tunnel excavation.

The model test system is mainly composed of a rigid test frame, a ground stress loading system, a hydraulic loading system, a muddy water protrusion recovery system, and multiple information monitoring and acquisition systems. The test system has the advantages of significant stiffness, visualization, easy operation, and wide application. It can realize the study of the disaster mechanism of water inrush and mud inrush through tunnel monitoring data collection and multi-information analysis at each stage of the test process.

Figure 1 is the main body of the model rigid test frame. The test frame is seamlessly welded by a 1.2 cm thick steel plate, and the base is made of an I-beam of 0.5 cm thickness. Small holes are evenly opened on the brackets on both sides of the box to play a role in fixing and adjusting the height of the reaction frame. Other structures such as plexiglass and stiffened rib plates on the front and back sides of the box are connected by flanges, while waterproof treatment is done around.

The ground stress loading system is composed of a separated hydraulic jack, hydraulic pump, pressure gauge, etc. Before system assembly, the in situ stress to be supplemented by the loading system shall be determined according to the geometric similarity ratio, stress similarity ratio, simulated surrounding rock bulk density, and actual buried depth of the test model. Combined with the area of the bearing area of the model, the real force to be applied can be calculated, and the measuring range of the jack top can be determined on this basis. Considering that the subsequent simulation test of water and mud inrush disaster, the movable position of reaction frame, and the filling height of materials during the test may be carried out for the deeper buried tunnel, the tonnage of separated hydraulic jack is 20 t, the stroke of piston rod is 10 cm, and the inner diameter of oil cylinder is 6.4 cm. The conversion relationship between supplementary in situ stress and pressure gauge reading is as follows [36, 37]:

The hydraulic loading system is mainly composed of a gas-liquid composite constant pressure water tank, a high-pressure nitrogen cylinder, and auxiliary equipment, as shown in Figure 2. The constant pressure water tank is made of stainless steel and can withstand a pressure of 0.3 MPa. There are three holes on the top of the water tank: the water inlet, the air inlet, and the pressure gauge interface. The bottom of the water tank is the water outlet. The air inlet of the water tank is connected to a high-pressure nitrogen cylinder through a hose, and the water outlet is connected to a water outlet through a rubber tube with an inner diameter of 12 mm to provide water for the model. The volume of the high-pressure nitrogen cylinder is 40 L, and the gas pressure in the bottle is about 13 MPa. In order to meet the pressure required by the test, a pressure-reducing valve is arranged at the gas outlet to reduce the output pressure in the bottle, thereby providing a stable air pressure source.

The multi-information monitoring and acquisition system includes monitoring components and data acquisition systems. The monitoring components used in the test mainly include micro earth pressure box, pore water pressure sensor, displacement meter, high-definition filming instruments, and others, which monitor the signals of surrounding rock stress, pore water pressure, displacement, and macro process of surrounding rock from fracture generation to water and mud emergence through the tunnel excavation process and hydraulic loading process, respectively. The earth pressure cell used for monitoring is a DMTY earth pressure cell, with a measuring range of 500 kPa, a specification of 28 × 10 mm, a sensitivity coefficient of 0.256∼0.270 kPa/με, a full bridge connection, and a bridge resistance of 350 Ω. The self-contained line includes two power lines. Moreover, two signal lines can work in the water-saturated medium. The element for monitoring pore water pressure is the DMKY pore water pressure sensor produced by the same company, with a range of 200 kPa, a specification of 32 × 15 mm, and a sensitivity coefficient of 0.100∼0.106 kPa/με. Working at 120% of the rated range, the miniature sensor used in the test is shown in Figure 3.

The data acquisition system includes strain gauges and data acquisition software, as shown in Figure 4. According to the number of embedded sensors, select the XL2118A24 static resistance strain gauge. This model has 24 data acquisition channels, measuring stress, strain, force, and other physical quantities. The operating mode of the instrument has two kinds of automatic control of the machine and external control of the computer. When using external computer control, as long as the USB connection line equipped with the instrument is used to connect the strain gauge with the computer equipped with this type of data acquisition software and set the sensor’s parameters, the real-time data acquisition can be realized.

The mud and water protrusion recovery system includes a 0.2 mm diameter cylindrical filter sieve, a water sealing ring, a 0.03 mm diameter cylindrical filter sieve, a transparent plastic panel, a water storage container, a capacity scale plate, a wheel bracket, a positioning scale, and a water outlet. The water seal ring is set at the connection of each layer of filter sieve, the transparent plastic panel is installed on the sidewall of the cylindrical filter sieve with 0.03 mm particle size, and the bottom of the water storage container is rounded. The capacity scale plate is located on the sidewall of the water storage container, and the water outlet is installed at the lowest point of the water storage container. The retractable wheel bracket is located at the bottom of the water storage container, and the positioning scale can adjust the level and height of the mud and water protrusion recovery system.

As shown in Figure 6, the tunnel’s area has a complex geological environment and well-developed fault structures. It has traversed six faults, including Wulishao, Yanzi’s Nest, Shuizhai, Yijingshui Fault, Shiguandi Fault, and Banjiazhai as well as the Jinjiashan syncline, and there are threefold structures including Yangjiashan inverted anticline and five karst areas. The Dazhu Mountain Tunnel is rich in groundwater. According to the relationship between the excavated water volume and the designed water volume of the revealed section, it is estimated that the maximum water inflow of the tunnel can reach three times the original design, that is, 360000 m3/d. Since the start of the Dazhu Mountain Tunnel, the tunnel has suffered deep water and mud inrush disasters, with about 200 million m3 of water gushing, which is equivalent to 15 West Lakes. This paper chooses the IV grade weak surrounding rock, which accounts for about 30% of the main tunnel of the Dazhu Mountain Tunnel, as the prototype of the similar model test surrounding rock, and the geometric dimensions of the excavation section (width 6.16 and height 9.41 m) of the surrounding rock of the tunnel are used as the model, a prototype of excavation section size.

When conducting similar model tests, the model and prototype should be made to satisfy similar geometry, dynamics, and physics relationships between materials or media [38]. However, due to the objective conditions, it is impossible to achieve complete similarity between the model and the prototype, and it is often necessary to perform a similar transformation of the model.

The ratio of the same physical quantity between the prototype (P) and the model (M) in the similar model test is called the similarity ratio (C), and the mathematical expression between the three is [39]

According to the similarity theory of fluid-solid coupling, the mathematical model of fluid-solid coupling in continuous media is used, and the seepage equation, equilibrium equation, and effective stress equation can be expressed as follows [40–42].

The geometric similarity ratio is Cl = 80 selected according to the size of the test frame of the tunnel water and mud inrush model test system, the peak pressure provided by the loading system, and the actual situation of the model test object. The bulk density similarity ratio is Cγ = 1.2 as the primary similarity ratio, and the prototype and model can be derived from the similarity theory. The other physical and mechanical parameters and hydraulic property parameters are similar to the following examples:

Taking the Dazhu Mountain Tunnel Engineering of the Darui Railway as the research background, a large amount of grade IV weak surrounding rock and the corresponding excavation section size existing in the tunnel construction are used as the basis of the model test. According to the physical and mechanical parameters of the grade IV surrounding rock in the study area, combining fluid-solid coupling similarity theory and model test research, the similarity ratios of physical and mechanical parameters and hydraulic properties of similar materials are obtained, and the parameters of surrounding rock under ideal conditions are obtained, as shown in Table 1.

According to the test results of similar material parameters of each ratio and the ideal material, comparison can be obtained from the best ratio of similar materials for the surrounding rock of the tunnel water and mud inrush model test. The finalized similar material ratio is shown in Table 2. When the content of red clay is 6.35%, that is, the ratio of mountain sand : red clay : cement : water is equal to 12 : 0.95 : 0.7 : 1.3, the physical and mechanical parameters and hydraulic properties of similar materials in the surrounding rock are close to those of the similar ideal materials; specifically, the material capacity is between the ideal material capacity, while the material compressive strength and permeability coefficient differ from the similar ideal materials in the range of 1.01%∼2.46%. The difference between the compressive strength and permeability coefficient of the material and the similar ideal material ranges from 1.01% to 2.46%, indicating that the ratio of similar material can better meet the requirements of the surrounding rock material in the model test. A similar material of fault zone was selected as the solution with the lowest permeability coefficient among the ratios, that is, 1 : 1 : 0.4 for red clay : sand : gravel, and the material permeability coefficient was 5.39 × 10−4cm/s.

According to the geometric similarity ratio of the model test and the size of the excavation section of the prototype, the model test tunnel has a section width of 7.7 cm and a height of 11.76 cm. The interlaced distance between the filling fault and the tunnel designed by the experiment is twice the hole diameter, the interlacing angle is 60°, the fault thickness is 12.5 cm, and the inclined extension length is 18.75 cm. The corresponding actual thickness and length are 10 m and 15 m, respectively, buried in the upper part of the fault. The water outlet device provides stable water pressure for the fault and is used to simulate the high-pressure and water-rich faults encountered in tunnel construction. The test simulates the buried depth of the tunnel 500 m, and the filling height of similar materials in the rigid test box is about 92 cm, which is 40 cm higher than the tunnel vault. Since the ground stress provided by the filling material does not meet the requirements of the model test, additional supplements must be made through the ground stress loading system. The vertical stress is about 106 kPa, and the stress reaches a predetermined value through stepwise loading.

After the in situ stress loading is completed and the material deformation is stable, draw the tunnel excavation contour line at the reserved excavation position using the wooden tunnel section made with a ratio of 1 : 1 and carry out the tunnel excavation. The test adopts the full-section excavation method. Data collection is performed simultaneously as the excavation, and the excavation is stopped after the excavation length reaches 42 cm. Then turn on the water pressure loading system to supply water to the fault. The water pressure loading adopts a step-by-step pressurization method. The initial water pressure is 10 kPa, and the subsequent increase is 5 kPa (when the software monitoring data is stable, it can continue to be loaded to the lower water pressure); until the water and mud inrush occurs in the tunnel, the test is deemed to be over.

Using model tests to study the disaster mechanism of tunnel filling-type fault water and mud inrush is mainly realized by analyzing the monitoring data obtained during the test. Before the test, the monitoring section, monitoring points, and corresponding monitoring elements should be selected scientifically and reasonably according to the test purpose and test requirements so that the data collected by the test can accurately and comprehensively reflect the surrounding rock and fault filling during the evolution of the tunnel water and mud inrush. The dynamic change characteristics of objects can also achieve the purpose of reducing monitoring costs.

In order to study the change law of multiple information such as surrounding rock and fault stress and seepage pressure during the model test, the central monitoring components of the test include earth pressure box and pore water pressure sensor. Along the tunnel excavation direction, the test designed a total of 2 monitoring sections, which were set at 1/2 position (Y = 25 cm) and 3/4 position (Y = 29.69 cm) in the direction of fault tendency. Monitoring section 1 has earth pressure boxes and pore water pressure sensors arranged around the tunnel, one time the diameter and two times the tunnel’s diameter. The primary function of the earth pressure boxes is to monitor the changes in the surrounding rock stress during tunnel excavation and water pressure loading. The pore water pressure gauge is used to monitor the seepage pressure information of the antioutburst rock mass between the tunnel and the fault. Three earth pressure boxes are arranged on the monitoring section 2, which correspond to the placement of the pore water pressure gauges on the monitoring section 1, which are used to monitor the stress changes of the antioutburst rock mass between the tunnel and the fault. The overall monitoring plan is shown in Figure 7.

In order to meet the requirements of compactness and uniformity of the model body, this test uses layered filling and layer-by-layer compaction. The model filling process is shown in Figure 8. The specific steps are as follows:(1)Before filling the materials, embed five prefabricated glass plates into the high-strength plexiglass opening positions at the front and rear of the rigid test frame (excluding the holes at the reserved tunnel excavation positions), and contact the plates with the glass. Apply glass glue to seal the part, then wrap the edge of the prefabricated wooden board with double-sided tape, and embed it in the hole at the tunnel excavation position on the plexiglass (for easy removal of the wooden board during excavation). After completion, put six pieces in front and back. The stiffening ribs are connected to the test frame by bolts.(2)Screen the raw materials required for the test, weigh the screened materials according to the selected similar material ratio, and weigh 120.4 kg of mountain sand, 9.5 kg of red clay, and 7.02 kg of cement each time and pour them into the mixer for mixing. After stirring evenly, pour in weighed 13.1 kg of water and stir for about 20 minutes.(3)Spread the mixed similar material in layers from bottom to top in the rigid test box, and then pound it manually. When the filling reaches the designed fault position, the prefabricated fault mold is positioned by tape measure, protractor, and other instruments and then continue to fill the similar material and compact the fixed mold.(4)When the height of material filling exceeds the height of the buried monitoring element, the monitoring element is buried at the designated position, and then the similar material is backfilled into the recess and compacted. All data lines are finally led uniformly from the gap position between the pressure equalization plate and the box.(5)When the material filling height reaches the design height of the fault, take out the mold and fill it with similar materials and gravel layers in sequence, bury the water outlet device, then continue to fill similar materials to the total design height, and scrape the top surface of the model body. After leveling, press the reaction frame and jack, place the pressure uniform plate on the top surface of the compacted and flattened model body, and finally load it to the initial ground stress step by step using a stepwise loading method.

Model body production process. (a) Embedded glass panel. (b) Filling materials. (c) Layer compaction. (d) Mold positioning. (e) Embedded monitoring elements. (f) Molding. (g) Filling fault buried water pipe. (h) Install reaction frame and jack. (i) Hydraulic loading.

After the model was deformed and stabilized, start to excavate the tunnel. Debug the test system before excavation, remove the stiffening ribs and planks at the tunnel excavation position, use the prepared tunnel excavation control mold to draw the tunnel excavation contour line at the excavation site, and carry out the tunnel excavation (as shown in Figure 9). Excavation simultaneously collects surrounding rock stress change data.

After the tunnel excavation is completed, use the hydraulic loading system to load the water pressure. During the loading process, the changes of surrounding rock stress, seepage pressure, and other data shall be paid attention to, but the water inrush position in the tunnel and the formation process of the inrush channel shall be paid the HD shooting system record attention. A particular person shall be specially assigned for data acquisition, photography, and recording until the physical model test of water and mud inrush in the tunnel is completed.

In order to study the characteristics of the hydraulic gradient changes inside the antiburst rock and fault, the local hydraulic gradient of two adjacent points can be calculated based on the pore water pressure values of two adjacent measurement points and the distance between measurement points, that is, the adjacent hydraulic gradient. The hydraulic gradient variation law inside the model body is obtained according to the pore water pressure value and the adjacent distance of each measurement point, as shown in Figure 12.

Figure 12 shows that as the vertical distance from the upper boundary of the fault increases, the hydraulic gradient inside the model body first increases and then decreases. Taking the hydraulic gradient change when the loading water pressure is 20 kPa as an example, the vertical distance from the upper boundary of the fault is within the range of 0∼12.5 cm, and the hydraulic gradient inside the model body is 0.409. When the distance increases to 12.5∼18.38 cm, the hydraulic gradient is 1.847, which