Sand soil vibration liquefaction simulation device and testing method thereof

Abstract

The application relates to the technical field of ground material analysis methods, and discloses a sand vibration liquefaction simulation device and a testing method thereof, which comprises a box body for placing a sand sample, and an opening is formed in the upper surface of the box body; a counterweight mechanism is arranged on the upper surface of the sand sample in the box body, the counterweight mechanism covers the upper surface of the sand sample, is used for applying pressure to the sand sample, and a plurality of drainage holes are formed in the counterweight mechanism; a vibration mechanism connected with the box body is arranged below the box body and is used for vibrating the box body to simulate sand vibration conditions; a pressure sensor, a laser range finder and an acceleration sensor are further arranged and are used for measuring test parameters of the sand sample in real time; constant load can be provided in the sand liquefaction simulation process; the counterweight mechanism is provided with the drainage holes, water in the saturated sand sample is discharged through the drainage holes when the counterweight mechanism applies pressure, stress borne by the sand sample can all be regarded as effective stress, and test conditions of the sand sample are more in line with actual situations.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ground material analysis method, and particularly relates to a sand vibration liquefaction simulation device and a test method thereof. BACKGROUND

[0002] At present, the earthquake has strong uncertainty, when the earthquake occurs, the strong ground motion caused by the earthquake often induces sand soil liquefaction, so that the sand soil layer loses the bearing capacity, and then the ground bearing capacity is reduced, so that the building on the sand soil layer loses the bearing capacity required by the design, and the building is easy to be damaged; the sand soil layer is distributed in the river banks, delta regions and the like, and the distribution area is relatively wide, and the population in the river area is usually large, so analyzing the sand soil property has great significance for disaster prevention and early warning.

[0003] The existing sand soil liquefaction test device directly performs the liquefaction test by arranging saturated sand soil in a box, and in the experiment process, the saturated sand soil sample cannot discharge the water in the sand soil sample, so that the stress received is different from the stress condition of the actual sand soil layer. SUMMARY

[0004] The present application aims to provide a sand vibration liquefaction simulation device and a test method thereof, which can apply a constant load to the top of the sand soil sample to discharge the water in the sand soil sample, so that the stress received by the sand soil sample can be converted into effective stress, and the test condition of the test sample is more in line with the stress condition of the actual sand soil layer.

[0005] In order to achieve the above-mentioned purpose, the present application provides a sand vibration liquefaction simulation device, which comprises a rack, a box for placing a sand soil sample, the box is arranged on the rack, and an opening is arranged on the upper surface of the box; a counterweight mechanism is arranged on the upper surface of the sand soil sample in the box, the counterweight mechanism covers the upper surface of the sand soil sample, and is used for applying pressure to the sand soil sample, the counterweight mechanism comprises a sieve plate arranged on the upper surface of the sand soil sample, and a counterweight table placed on the sieve plate; a plurality of water filtering holes are arranged on the sieve plate, and the length and width of the sieve plate are the same as the length and width of the inner wall of the box; a plurality of drainage holes are arranged on the counterweight table, and the drainage holes are communicated with the water filtering holes.

[0006] A vibration mechanism is arranged on the rack, and is used for vibrating the box to simulate the sand vibration condition.

[0007] Preferably, the counterweight mechanism further comprises a counterweight rod and a counterweight piece, the counterweight rod is perpendicular to the upper surface of the counterweight table; the counterweight piece is provided with a through hole matched with the counterweight rod, and the counterweight piece is placed on the counterweight table and is connected and limited with the counterweight rod through the through hole.

[0008] Further, the counterweight comprises: counterweight blocks, each of which has a specified weight, and a counterweight kettle, an inner part of which is provided with a cavity in which different substances can be added to change the overall weight of the counterweight kettle; and the through hole comprises a first counterweight hole and a second counterweight hole respectively provided on the counterweight blocks and the counterweight kettle.

[0009] Preferably, the rack comprises a support plate and a base supported on the ground, the box is arranged on the upper surface of the support plate, and the support plate is arranged above the base; the lower surface of the support plate is provided with a plurality of first limiting blocks, and the base is provided with a plurality of second limiting blocks corresponding to the first limiting blocks, and the first limiting blocks and the second limiting blocks are connected by springs; the vibration mechanism is connected with the support plate and drives the support plate to vibrate.

[0010] Further, the vibration mechanism comprises a hydraulic motor and an eccentric block, the hydraulic motor is connected with the support plate, and the eccentric block is connected to the power output shaft of the hydraulic motor.

[0011] Preferably, the device further comprises a lifting mechanism arranged above the counterweight mechanism, the lifting mechanism is connected with the counterweight mechanism and used to drive the counterweight mechanism to lift.

[0012] Further, the sand vibration liquefaction simulation device further comprises a support arranged on the rack, and the lifting mechanism is arranged on the support; the lifting mechanism comprises a connecting rope, a winch, a rotating shaft, a mounting seat and a brake mechanism, one end of the connecting rope is connected with the counterweight mechanism, the other end of the connecting rope is connected with the winch and wound around the outer periphery of the winch; the mounting seat is arranged on the support, the winch is arranged in the mounting seat, the rotating shaft passes through the middle part of the winch and is rotatably connected to the mounting seat at both ends; the brake mechanism is arranged in the mounting seat and connected with the winch and used to brake the winch.

[0013] Further, the brake mechanism comprises a brake bolt, a connecting block, a brake block and a plurality of brake pieces, the connecting block is arranged in the mounting seat, the brake bolt is threadedly connected with the connecting block, the brake block is rotatably connected with the connecting block, and one end of the brake bolt abuts against the brake block; the brake pieces comprise a first friction piece arranged at the other end of the brake block and a second friction piece arranged on the mounting seat corresponding to the first friction piece, the first friction piece and the second friction piece are respectively located on the two sides of the winch, and the winch rotates between the first friction piece and the second friction piece; when the brake bolt rotates and moves, the brake block can be pushed to rotate, the first friction piece is driven to approach the second friction piece, and the winch is clamped.

[0014] Preferably, a guide hole is formed in the support, a vertical guide rod is arranged on the counterweight platform, the guide rod moves with the counterweight platform, the guide rod passes through the guide hole and moves along the opening direction of the guide hole.

[0015] Preferably, the test method of the sand vibration liquefaction simulation device comprises the following steps:

[0016] S1: a saturated sand sample is prepared in the box by a sand drop method in water, a pore water pressure gauge, a soil pressure gauge and an acceleration sensor are embedded in the sand sample during the preparation process, a laser range finder is installed on the support, and an acceleration sensor is installed on the support plate;

[0017] S2: the counterweight platform is adjusted to a suitable height by rotating the winch, and the counterweight platform is fixed by a brake mechanism; then, counterweight pieces corresponding to the required load are added to the counterweight platform;

[0018] S3: the sieve plate is laid on the upper surface of the saturated sand sample, then the winch is driven to slowly lower the counterweight platform, when the counterweight platform contacts the sieve plate, the connecting rope is disconnected from the counterweight mechanism, and the lowering displacement of the counterweight platform is measured by the laser range finder;

[0019] S4: after the counterweight platform is stabilized, the hydraulic motor is started to drive the eccentric block to rotate, so that the box and the saturated sand sample inside are vibrated, the vibration condition of sand liquefaction is simulated, and the saturated sand sample is liquefied; and the data of the pore water pressure gauge, the soil pressure gauge and the acceleration sensor before vibration, during vibration and after vibration when the pore water pressure is completely dissipated are recorded;

[0020] S5: the parameters when the load is F1, F2, F3, F4, …, F n are respectively tested according to the above steps, wherein F1=0, the saturated sand sample cannot be liquefied when the load is F n , the values of F2 to F n are in an arithmetic progression; and the required sand liquefaction characteristic data are obtained by calculation based on the measured parameters.

[0021] Compared with the prior art, the sand vibration liquefaction simulation device and the test method thereof have the beneficial effects that the counterweight mechanism arranged above the sand sample can provide a dead load during the sand liquefaction simulation process, the drainage hole arranged on the counterweight mechanism can discharge the water in the saturated sand sample while the counterweight mechanism applies pressure, the stress on the sand sample can be regarded as effective stress, the test condition of the sand sample is more in line with the actual situation, and the test result is more accurate. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is the overall structure schematic diagram of the sand vibration liquefaction simulation device of the embodiment of the present application.

[0023] Figure 2 is the structure schematic diagram of the box and support plate of the sand vibration liquefaction simulation device of the embodiment of the present application.

[0024] Figure 3 is the base structure schematic diagram of the sand vibration liquefaction simulation device of the embodiment of the present application.

[0025] Figure 4 is the connection schematic diagram of the first limiting block and the second limiting block of the sand vibration liquefaction simulation device of the embodiment of the present application.

[0026] Figure 5 is the disassembled structure schematic diagram of the counterweight structure of the sand vibration liquefaction simulation device of the embodiment of the present application.

[0027] Figure 6 is the connection schematic diagram of the box of the sand vibration liquefaction simulation device of the embodiment of the present application.

[0028] Figure 7 is the structure schematic diagram of the hydraulic motor of the sand vibration liquefaction simulation device of the embodiment of the present application.

[0029] Figure 8 is the eccentric block structure schematic diagram of the sand vibration liquefaction simulation device of the embodiment of the present application.

[0030] Figure 9 is the structure schematic diagram of the lifting mechanism of the sand vibration liquefaction simulation device of the embodiment of the present application.

[0031] Figure 10 is the structure schematic diagram of the brake mechanism of the sand vibration liquefaction simulation device of the embodiment of the present application.

[0032] In the figure, 1, rack; 11, support plate; 111, first limiting block; 12, base; 121, second limiting block; 122, telescopic push rod; 13, spring; 14, support; 2, box; 3, counterweight mechanism; 31, sieve plate; 311, water filter hole; 32, counterweight table; 321, drainage hole; 33, counterweight rod; 34, counterweight; 341, counterweight block; 342, counterweight kettle; 4, vibration mechanism; 41, hydraulic motor; 42, eccentric block; 5, sensor; 51, pore water pressure gauge; 52, soil pressure gauge; 53, acceleration sensor; 54, laser range finder; 6, lifting mechanism; 61, connecting rope; 62, winch; 63, rotating shaft; 64, mounting seat; 65, brake mechanism; 651, brake bolt; 652, connecting block; 653, brake block; 654, brake pad; 655, brake spring. DETAILED DESCRIPTION

[0033] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate the present application, but are not used to limit the scope of the present application.

[0034] In the description of the present application, it should be understood that in the description of the present application, it should be understood that the terms "upper", "lower" and the like indicating the orientation or positional relationship in the present application are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" and the like are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0035] As shown in Figures 1-6 The sand vibration liquefaction simulation device of the preferred embodiment of the present application comprises a rack 1, a box 2 for placing a sand sample, the box 2 being arranged on the rack 1, an opening being formed on the upper surface of the box 2; a counterweight mechanism 3 being laid on the upper surface of the sand sample in the box 2, the counterweight mechanism 3 covering the upper surface of the sand sample, for applying pressure to the sand sample, the counterweight mechanism 3 comprising a sieve plate 31 laid on the upper surface of the sand sample, and a counterweight table 32 placed on the sieve plate 31; a plurality of water filtering holes 311 being arranged on the sieve plate 31, the length and width of the sieve plate 31 being the same as the length and width of the inner wall of the box 2; a plurality of drainage holes 321 being formed on the counterweight table 32, the drainage holes 321 being in communication with the water filtering holes 311;

[0036] A vibration mechanism 4 is installed on the rack 1 for vibrating the box 2 to simulate the sand vibration condition.

[0037] Specifically, during the test, the rack 1 is vertically placed, the box 2 is arranged on the rack 1, the upper surface of the box 2 is opened, the sand sample is taken and placed, and the counterweight mechanism 3 is adjusted. Preferably, the box 2 is made of high-transparency polyvinyl chloride material plate, which is convenient for observing the test effect; the sand sample is placed in the box 2, the upper surface of the sand sample is kept horizontal, the counterweight mechanism 3 is placed on the upper surface of the sand sample, the counterweight mechanism 3 provides constant load to the sand sample; the sieve plate 31 is laid on the upper surface of the prepared sand sample, a plurality of water filtering holes 311 are formed in the sieve plate 31, the size of the water filtering holes 311 is small, which is convenient for the water in the sand sample to seep out and prevent the sand sample from overflowing from the water filtering holes 311, the length and width of the sieve plate 31 are the same as the length and width of the inner wall of the box 2, which ensures that the sieve plate 31 can completely cover the sand sample, and the sand sample cannot overflow from the side of the sieve plate 31, the counterweight table 32 is laid on the upper surface of the sieve plate 31 to provide load, a plurality of drainage holes 321 are arranged on the counterweight table 32 and communicated with the water filtering holes 311, which can extrude the sand sample and make the water in the sand sample be extruded under pressure, the extruded water is discharged through the water filtering holes 311 and the drainage holes 321, so as to facilitate the conversion of the load into effective stress; the lower portion of the box 2 is provided with the vibration mechanism 4 mounted on the rack 1, the vibration mechanism 4 is used to drive the box 2 and the sand sample to vibrate, simulates the vibration of the sand in the actual situation, and makes the sand sample liquefy.

[0038] During the test, the sand sample is first placed in the box 2 and the upper surface is kept horizontal, then the weight of the counterweight mechanism 3 is adjusted according to the required test data, the sieve plate 31 and the counterweight table 32 are sequentially placed on the sand sample to apply stable constant load from the upper surface of the sand sample, simulate the actual stress condition of the sand layer, and extrude and discharge the water in the sand sample; after confirming that the stress condition meets the requirements of the test, the vibration mechanism 4 is started, the vibration mechanism 4 drives the box 2 to vibrate, provides the vibration condition required by the test, and makes the sand sample liquefy under the vibration condition, the above test process is detected and recorded by the sensor 5, and finally the characteristic parameters of the required sand sample are obtained by calculating the measured data.

[0039] Preferably, the sensor 5 includes a pore water pressure gauge 51, a soil pressure gauge 52, an acceleration sensor 53 and a laser range finder 54, the acceleration sensor 53, the pore water pressure gauge 51 and the soil pressure gauge 52 are arranged in the sand sample to detect the related parameter data of the sand sample during the test, the acceleration sensor 53 is also arranged outside the box 2 to measure the input acceleration provided by the vibration mechanism 4, and the laser range finder 54 is arranged above the counterweight mechanism 3 to detect the displacement of the counterweight mechanism 3 when the pressure is applied, and judge whether the sand sample is stable after the load is increased.

[0040] The device and the test method can provide constant load for the sand sample, discharge the moisture in the sand sample while applying the constant load, ensure that the applied constant load is converted into effective stress, make the test condition closer to the actual situation, and make the test data more accurate.

[0041] As shown in Figure 1 , Figure 5 and Figure 6 , preferably, the counterweight mechanism 3 further comprises a counterweight rod 33 and a counterweight 34, the counterweight rod 33 is perpendicular to the upper surface of the counterweight table 32; the counterweight 34 is provided with a through hole matched with the counterweight rod 33, and the counterweight 34 is placed on the counterweight table 32 and connected and limited with the counterweight rod 33 through the through hole.

[0042] Specifically, the counterweight rod 33 is provided with multiple counterweight rods, which are uniformly and vertically arranged on the upper surface of the counterweight table 32, and the lower end of the counterweight rod 33 is connected with the counterweight table 32; the through hole of the counterweight 34 has the same diameter as the diameter of the counterweight rod 33, the counterweight 34 can be matched and limited with the counterweight rod 33 from the upper end of the counterweight rod 33, and the counterweight 34 is moved along the counterweight rod 33 to be fixed at the lower end of the counterweight rod 33, so that the counterweight mechanism 3 reaches the required weight for the test, and provides constant load for the sand sample.

[0043] Further, the counterweight 34 comprises a counterweight block 341 and a counterweight kettle 342, multiple counterweight blocks 341 are all of specified weight, the counterweight kettle 342 is internally provided with a cavity in which different substances can be added to change the overall weight of the counterweight kettle 342; the through hole comprises a first counterweight hole and a second counterweight hole respectively arranged on the counterweight block 341 and the counterweight kettle 342.

[0044] Specifically, the plurality of counterweights 341 are of the same weight, the counterweights 341 are placed at the lower ends of the counterweight rods 33 in advance of the counterweight pots 342 and the counterweight rods 33 to provide a basic weight, so that the sieve plate 31 and the counterweight table 32 are stably placed on the sand sample, and water or sand is added in the counterweight pots 342 according to the required counterweight to adjust the overall weight of the counterweight pots 342, the counterweight pots 342 are placed on the counterweights 341 after the counterweights 341 are placed, and the counterweight pots 342 are uniformly stacked on the counterweights 341 to provide the required pressure for the test; the middle parts of the counterweights 341 and the counterweight pots 342 are respectively provided with first counterweight holes and second counterweight holes connected with the counterweight rods 33, the first counterweight holes and the second counterweight holes are correspondingly arranged to ensure that the pressures applied by the counterweights 341 and the counterweight pots 342 are uniform; during the vibration test, the counterweight rods 33 abut in the first counterweight holes and the second counterweight holes, so that the counterweights 341 and the counterweight pots 342 cannot horizontally displace, the counterweights 341 and the counterweight pots 342 themselves have a large mass, which ensures that they do not vertically displace, and a fixing bolt can also be arranged on the counterweight rod 33 after the counterweights 341 and the counterweight pots 342 are stabilized, the fixing bolt abuts against the upper surface of the uppermost counterweight pot 342, which ensures that the counterweights 341 and the counterweight pots 342 do not vertically displace during the vibration; and the counterweights 341 and the counterweight pots 342 are uniformly arranged on the counterweight rods 33, which ensures that the sand sample is uniformly stressed.

[0045] Preferably, the rack 1 comprises a support plate 11 and a base 12 supported on the ground, the box body 2 is arranged on the upper surface of the support plate 11, and the support plate 11 is arranged above the base 12; the lower surface of the support plate 11 is provided with a plurality of first limiting blocks 111, and the base 12 is provided with a plurality of second limiting blocks 121 corresponding to the first limiting blocks 111, and the first limiting blocks 111 and the second limiting blocks 121 are connected through springs 13; the vibration mechanism 4 is connected with the support plate 11 and drives the support plate 11 to vibrate.

[0046] As Figure 3 and Figure 4As shown, specifically, the base 12 is welded by a plurality of square steel, the base 12 is vertically placed on the ground, the base 12 is used for installing and placing related test equipment, the upper surface of the base 12 is provided with a plurality of second limiting blocks 121, the lower end of the plurality of springs 13 is correspondingly sleeved on the outer periphery of the second limiting block 121; the support plate 11 is arranged above the base 12 corresponding to the upper surface of the base 12, the lower surface of the support plate 11 is provided with a plurality of first limiting blocks 111 corresponding to the second limiting block 121, the upper end of the spring 13 is sleeved on the outer periphery of the first limiting block 111, so that the support plate 11 is connected with the base 12, when the box 2 on the support plate 11 is fully loaded, the first limiting block 111 and the second limiting block 121 do not directly contact, because the support plate 11 and the base 12 are flexibly connected, the vibration mechanism 4 drives the support plate 11 to vibrate, and the base 12 is not vibrated at the same time, so that the stability of the base 12 placed can be improved and the influence of the weight of the base 12 on the vibration test can be avoided.

[0047] In addition, the base 12 is also provided with a telescopic push rod 122, the lower end of the telescopic push rod 122 is connected with a roller, the telescopic push rod 122 can abut on the ground and make the base 12 rise when being extended; when it is needed to move the device, the telescopic push rod 122 can be extended so that the roller at the lower end thereof is in contact with the ground, the base 12 does not contact with the ground at this time, and the device can be pushed to move, when it is not needed to move, the telescopic push rod 122 is adjusted to be shortened, so that the bottom of the base 12 is in contact with the ground, and the base 12 cannot be easily moved at this time.

[0048] Preferably, the vibration mechanism 4 comprises a hydraulic motor 41 and an eccentric block 42, the hydraulic motor 41 is connected with the support plate 11, and the eccentric block 42 is connected to the power output shaft of the hydraulic motor 41.

[0049] As shown in Figure 7 and Figure 8 , specifically, the hydraulic motor 41 converts the hydraulic energy of high-pressure liquid into mechanical energy of the power output shaft, and has a small structure and is convenient to move; the power output shaft of the hydraulic motor 41 is provided with a positioning groove, the positioning groove is provided with a key groove, the eccentric block 42 is fixed in the positioning groove through a flat key and a bolt, so as to ensure that the eccentric block 42 rotates with the power output shaft of the hydraulic motor 41 and the stability of the movement of the eccentric block 42, the eccentric block 42 is driven to rotate by the power output shaft to generate a vibration excitation force, directly driving the support plate 11 and the box 2 to vibrate, simulating the stress condition of the sand soil sample when the sand soil sample is liquefied, and adjusting the rotating speed of the power output shaft can adjust the stress condition of the sand soil sample.

[0050] Preferably, the sand soil vibration liquefaction simulation device further comprises a lifting mechanism 6 arranged above the counterweight mechanism 3, the lifting mechanism 6 is connected with the counterweight mechanism 3 and is used for driving the counterweight mechanism 3 to lift.

[0051] Specifically, the lifting mechanism 6 is connected with the counterweight mechanism 3, can control the counterweight mechanism 3 to rise, facilitate to take and place the sand sample or adjust the counterweight, control the counterweight mechanism 3 to descend, can make the counterweight mechanism 3 contact with the sand sample, carry out the test.

[0052] As shown in Figure 1 、 Figure 6 、 Figure 9 and Figure 10 Further, the sand vibration liquefaction simulation device further comprises a support 14 arranged on the frame 1, and the lifting mechanism 6 is arranged on the support 14; the lifting mechanism 6 comprises a connecting rope 61, a winch 62, a rotating shaft 63, a mounting seat 64 and a brake mechanism 65; one end of the connecting rope 61 is connected with the counterweight mechanism 3, and the other end of the connecting rope 61 is connected with the winch 62 and wound around the outer periphery of the winch 62; the mounting seat 64 is arranged on the support 14, the winch 62 is arranged in the mounting seat 64, the rotating shaft 63 penetrates through the middle part of the winch 62 and is rotatably connected with the mounting seat 64 at both ends; the brake mechanism 65 is arranged in the mounting seat 64 and connected with the winch 62, and is used for braking the winch 62.

[0053] Specifically, the support 14 is arranged on both sides and the top of the box 2, both ends of the support 14 are connected with the base 12 respectively, the main body of the lifting mechanism 6 is installed on the part of the support 14 above the box 2, the lower end of the connecting rope 61 is connected with the middle part of the counterweight mechanism 3 through a hook, the hook is convenient to disassemble, and being connected with the middle part of the counterweight mechanism 3 can make the counterweight mechanism 3 rise evenly without tilting; the mounting seat 64 is fixed on the support 14, the winch 62 is rotatably connected with the inside of the mounting seat 64 through the rotating shaft 63, both ends of the rotating shaft 63 are rotatably connected with the mounting seat 64 through bearings, the rotating shaft 63 and the winch 62 can be driven by electricity or manually; the upper end of the connecting rope 61 is connected with the winch 62 and wound around the outer periphery of the winch 62, when the connecting rope 61 is connected with the counterweight mechanism 3, the counterweight mechanism 3 is controlled to rise or descend by rotating the winch 62; the brake mechanism 65 can be connected with the winch 62, when connected, the brake mechanism 65 makes the winch 62 unable to rotate, when the brake mechanism 65 is not connected with the winch 62, the winch 62 can rotate normally to control the motion state of the winch 62.

[0054] Further, the brake mechanism 65 comprises a brake bolt 651, a connecting block 652, a brake block 653 and a plurality of brake pieces 654. The connecting block 652 is arranged in the interior of the mounting seat 64, the brake bolt 651 is threadedly connected with the connecting block 652, the brake block 653 is rotationally connected with the connecting block 652, and one end of the brake bolt 651 abuts against the brake block 653. The brake piece 654 comprises a first friction piece arranged at the other end of the brake block 653, and a second friction piece arranged on the mounting seat corresponding to the first friction piece. The first friction piece and the second friction piece are respectively located at two sides of the winch 62, and the winch 62 rotates between the first friction piece and the second friction piece. When the brake bolt 651 rotates and moves, the brake block 653 is pushed to rotate, and the first friction piece is driven to approach the second friction piece to clamp the winch 62.

[0055] Specifically, the connecting block 652 is arranged in the interior of the mounting seat 64, the brake bolt 651 is threadedly connected with the connecting block 652, the brake bolt 651 is inserted from one end of the connecting block 652, and the brake bolt 651 rotates to pass through the connecting block 652 and exit from the other end of the connecting block 652. One end of the brake block 653 is rotationally connected with the other end of the connecting block 652 through a rotating shaft. In addition, the brake block 653 is further connected with the connecting block 652 through a brake spring 655. The brake spring 655 always provides a pulling force to make the one end of the brake block 653 abut against the other end of the connecting block 652. When the brake bolt 651 rotates to pass through the connecting block 652, the brake bolt 651 abuts against the brake block 653, and the brake bolt 651 continuously rotates to push the brake block 653 to rotate around the rotating shaft. The other end of the brake block 653 is provided with the brake piece 654, and the brake piece 654 is located at two sides of the winch 62. In the normal state, the brake block 653 is subjected to the pulling force of the brake spring 655, the brake piece 654 does not contact the winch 62, and the winch 62 can normally rotate. When the brake bolt 651 rotates to abut against the brake block 653, the brake bolt 651 continues to rotate to make the brake block 653 rotate, the first friction piece approaches the second friction piece, and the first friction piece contacts the winch 62. With the continuous advancement of the brake bolt 651, the first friction piece makes the winch 62 slightly inclined to contact the second friction piece, the first friction piece and the second friction piece clamp the winch 62, and the purpose of braking the winch 62 is achieved, so that the winch 62 cannot rotate.

[0056] The support 14 is provided with a guide hole, and the counterweight table 32 is provided with a vertical guide rod which moves with the counterweight table 32. The guide rod passes through the guide hole and moves along the opening direction of the guide hole.

[0057] Specifically, the guide rod is vertically arranged at the position close to the two sides of the counterweight mechanism 3, the support 14 is provided with a guide hole corresponding to the guide rod, the guide rod passes through the guide hole and can move up and down along the guide hole, so that the counterweight mechanism 3 can move along the opening direction of the guide hole under the driving of the lifting mechanism 6, and the counterweight platform 32 can complete the lifting operation in the vertical direction.

[0058] Further, the connecting parts of the power output shaft of the hydraulic motor 41 and the eccentric block 42, the first limiting block 111 and the second limiting block 121 and the spring 13, the connecting block 652 and the brake bolt 651, and the rotating shaft are coated or injected with lubricating oil, so as to reduce the friction of the connecting parts.

[0059] A test method of a sand vibration liquefaction simulation device, the steps of which comprise:

[0060] S1: A saturated sand sample is prepared in the box 2 by the sand falling method in water, the pore water pressure gauge 51, the earth pressure gauge 52 and the acceleration sensor 53 are buried in the sand sample during the preparation process, the laser range finder 54 is installed on the support 14, and the acceleration sensor 53 is installed on the support plate 11;

[0061] S2: The counterweight platform 32 is adjusted to a suitable height by rotating the winch 62, and the counterweight platform 32 is fixed by the brake mechanism 65; then the counterweight 34 corresponding to the required load for testing is added to the counterweight platform 32;

[0062] S3: The sieve plate 31 is laid on the upper surface of the saturated sand sample, then the winch 62 is driven to slowly lower the counterweight platform 32, when the counterweight platform 32 contacts the sieve plate 31, the connecting rope 61 is disconnected from the counterweight mechanism 3, and the lowering displacement of the counterweight platform 32 is measured by the laser range finder 54;

[0063] S4: After the counterweight platform 32 is stabilized, the hydraulic motor 41 is started to drive the eccentric block 42 to rotate, so that the box 2 and the saturated sand sample in the box 2 are vibrated, the sand sample is liquefied under the simulated sand liquefaction vibration condition, and the data of the pore water pressure gauge 51, the earth pressure gauge 52 and the acceleration sensor 53 before vibration, during vibration and after vibration when the pore water pressure completely disappears are recorded;

[0064] S5: The parameters under the loads F1, F2, F3, F4, …, F n are respectively tested according to the above steps, wherein F1=0, the saturated sand sample cannot be liquefied under the load F n , the values of F2 to F n are in an arithmetic progression, and the required sand liquefaction characteristic data are obtained by calculation based on the measured parameters.

[0065] Specifically, a certain amount of distilled water is first injected into the box 2, and then the sandy soil is slowly put into the distilled water to ensure that the voids of the sandy soil sample are fully filled with distilled water, and finally a saturated sandy soil sample is formed; during the preparation of the saturated sandy soil sample, the pore water pressure gauge 51, the soil pressure gauge 52 and the acceleration sensor 53 are buried at a predetermined position inside the saturated sandy soil sample, the laser range finder 54 is installed on the support 14 above the box 2, and another acceleration sensor 53 is installed on the support plate 11, and the preparation work is completed;

[0066] The height of the counterweight table 32 is adjusted to above the box 2 by the winch 62, and the winch 62 is fixed by the brake mechanism 65, which facilitates the placement or replacement of the counterweight 34. According to the simulated stress condition of the sandy soil, the counterweight 34 with the same weight is selected and evenly arranged on each counterweight rod 33, and the counterweighting is completed.

[0067] The sieve plate 31 is laid on the upper surface of the saturated sandy soil sample to ensure that the sieve plate 31 is in close contact with the upper surface of the sandy soil sample and is horizontally arranged; after confirming that the sieve plate 31 is arranged, the brake bolt 651 is adjusted to make the brake shoes 654 on both sides of the winch 62 slightly away from each other, at this time the winch 62 can be slowly rotated, the counterweight table 32 slowly moves downward along the guide rod, and when the counterweight table 32 descends to contact the sieve plate 31, the hook is separated from the counterweight table 32, the counterweight table 32 is pressed downward by its own weight and the weight of the counterweight 34, and at the same time the guide rod can be removed from the counterweight table 32 to ensure that the counterweight of the counterweight table 32 is uniform; after the hook is disconnected from the counterweight table 32, the laser range finder 54 measures the displacement of the counterweight table 32 to facilitate the judgment of whether the compression deformation of the sandy soil sample is stable after the load of the counterweight table 32 is applied.

[0068] After the counterweight table 32 is stable, the hydraulic motor 41 is started, the power output shaft of the hydraulic motor 41 drives the eccentric block 42 to rotate, providing vibration to the support plate 11, the support plate 11 drives the box 2 and the sandy soil sample to vibrate, the sandy soil sample is liquefied by vibration, and the parameters of the sandy soil sample are detected by the acceleration sensor 53, the pore water pressure gauge 51 and the soil pressure gauge 52 to obtain relevant test parameters.

[0069] The relevant parameters of the sandy soil sample under the counterweight load of F1, F2, F3, F4, …, F n are tested respectively, the collected parameters are calculated, and the liquefaction characteristics of the saturated sandy soil sample under different effective stress conditions are summarized.

[0070] Further, the calculation process of the theoretical effective stress σ' (kPa) of the saturated sandy soil at the buried depth h (m) is as follows:

[0071] ρ d = m s / v;

[0072] e = G s p w / p d -1;

[0073] g' = [(G s -1) p w g] / (1+e);

[0074] s' = g' h + (F n +N1+N2) / S;

[0075] wherein p d is the dry density of the saturated sand sample, in g / cm 3 ;

[0076] m s : the mass of the saturated sand sample, which can be measured after the sand sample is dried, in g;

[0077] v: the volume of the saturated sand sample, which can be calculated according to the size of the box 2 and the height of the saturated sand sample, in cm 3 ;

[0078] e: the void ratio, in 1;

[0079] G s : the specific gravity of the sand, which can be obtained by indoor test, in 1;

[0080] p w : the density of distilled water, in g / cm 3 ;

[0081] g: the acceleration of gravity, in m / s 2 ;

[0082] g': the effective gravity of the saturated sand sample, in kN / m 3 ;

[0083] S: the internal area of the box 2, in m 2 ;

[0084] N1: the weight of the counterweight table 32, in kN;

[0085] N2: the weight of the sieve plate 31, in kN.

[0086] Specifically, the density of the dried sand sample is obtained by dividing the mass of the sand sample by the volume, the specific gravity of the sand and the density of the distilled water can be measured before the test as known parameters, and the effective gravity of the saturated sand sample can be calculated by the above parameters, and thus the theoretical effective stress for liquefaction of the saturated sand with a depth of h can be finally calculated.

[0087] The working process of the present application is as follows: firstly, a certain amount of distilled water is injected into the box 2, then the sandy soil is slowly put into the distilled water, ensuring that the voids of the sandy soil sample are fully filled with distilled water, and finally a saturated sandy soil sample is formed; during the preparation of the saturated sandy soil sample, the pore water pressure gauge 51, the soil pressure gauge 52 and the acceleration sensor 53 are buried at the predetermined position inside the saturated sandy soil sample, the laser range finder 54 is installed on the support 14 above the box 2, and another acceleration sensor 53 is installed on the support plate 11, and the preparation work is completed;

[0088] The height of the counterweight table 32 is adjusted to the upper side of the box 2 by the winch 62, and the winch 62 is fixed by the brake mechanism 65, which is convenient for placing or replacing the counterweight 34, and the counterweight 34 is selected according to the simulated stress condition of the sandy soil, and the counterweight 34 is evenly arranged on each counterweight rod 33, and the counterweight is completed.

[0089] The sieve plate 31 is laid on the upper surface of the saturated sandy soil sample, ensuring that the sieve plate 31 is attached to the upper surface of the sandy soil sample and remains horizontally arranged; after confirming that the sieve plate 31 is arranged, the brake bolt 651 is adjusted to make the brake pads 654 on both sides of the winch 62 slightly away from each other, at this time the winch 62 can be slowly rotated, the counterweight table 32 slowly moves downward along the guide rod, and when the counterweight table 32 descends to contact the sieve plate 31, the hook is separated from the counterweight table 32, the counterweight table 32 is pressed downward by the weight of the counterweight 34 itself, and at the same time the guide rod can be removed from the counterweight table 32 to ensure that the counterweight of the counterweight table 32 is uniform; after the hook is disconnected from the counterweight table 32, the laser range finder 54 measures the displacement of the counterweight table 32, which is convenient for judging whether the compression deformation of the sandy soil sample is stable after the load of the counterweight table 32 is applied.

[0090] After waiting for the counterweight table 32 to be stable, the hydraulic motor 41 is started, the power output shaft of the hydraulic motor 41 drives the eccentric block 42 to rotate, providing vibration for the support plate 11, the support plate 11 drives the box 2 and the sandy soil sample to vibrate, making the sandy soil sample liquefy under vibration, and the parameters of the sandy soil sample are detected by the acceleration sensor 53, the pore water pressure gauge 51 and the soil pressure gauge 52, and the relevant test parameters are obtained.

[0091] The relevant parameters of the sandy soil sample under the counterweight load F1, F2, F3, F4, …, F n are tested respectively, the collected parameters are calculated, and the liquefaction characteristics of the saturated sandy soil sample under different effective stress conditions are summarized.

[0092] In summary, the sand vibration liquefaction simulation device and the testing method thereof provided by the embodiment of the present application provide constant load for the sand sample through the counterweight mechanism 3, facilitate the water in the sand sample to be discharged during the pressure application, facilitate the applied load to be converted into effective stress, and make the testing result closer to the actual stress condition of the sand stratum.

[0093] The above merely describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and replacements without departing from the technical principles of the present application, and these improvements and replacements should also be considered as the protection scope of the present application.

Claims

1. A sand vibration liquefaction simulation device characterized by comprising: It includes: The frame, the box for placing the sand sample, the box is arranged on the frame, the upper surface of the box is provided with an opening; the sand sample in the box is laid with a counterweight mechanism on the upper surface, the counterweight mechanism covers the upper surface of the sand sample, and is used for applying pressure to the sand sample, the counterweight mechanism comprises a sieve plate laid on the upper surface of the sand sample and a counterweight table placed on the sieve plate; a plurality of water filtering holes are arranged on the sieve plate, and the length and width of the sieve plate are the same as the length and width of the inner wall of the box; a plurality of drainage holes are arranged on the counterweight table, and the drainage holes are communicated with the water filtering holes; The frame is provided with a vibration mechanism for vibrating the box to simulate the vibration condition of the sand; The counterweight mechanism further comprises a counterweight rod and a counterweight piece, the counterweight rod is perpendicular to the upper surface of the counterweight table; the counterweight piece is provided with a through hole matched with the counterweight rod, and the counterweight piece is placed on the counterweight table and connected and limited with the counterweight rod through the through hole; The frame comprises a support plate and a base supported on the ground, the box is arranged on the upper surface of the support plate, and the support plate is arranged above the base; a plurality of first limiting blocks are arranged on the lower surface of the support plate, a plurality of second limiting blocks corresponding to the first limiting blocks are arranged on the base, and the first limiting blocks and the second limiting blocks are connected through springs; the vibration mechanism is connected with the support plate and drives the support plate to vibrate; The vibration mechanism comprises a hydraulic motor and an eccentric block, the hydraulic motor is connected with the support plate, and the eccentric block is connected with the power output shaft of the hydraulic motor; The sand vibration liquefaction simulation device further comprises a lifting mechanism arranged above the counterweight mechanism, the lifting mechanism is connected with the counterweight mechanism and used for driving the counterweight mechanism to lift; The sand vibration liquefaction simulation device further comprises a support arranged on the frame, and the lifting mechanism is arranged on the support; the lifting mechanism comprises a connecting rope, a winch, a rotating shaft, a mounting seat and a brake mechanism, one end of the connecting rope is connected with the counterweight mechanism, the other end of the connecting rope is connected with the winch and wound on the outer periphery of the winch; the mounting seat is arranged on the support, the winch is arranged in the mounting seat, the rotating shaft penetrates through the middle part of the winch and is rotationally connected with the mounting seat at both ends; the brake mechanism is arranged in the mounting seat and connected with the winch, and is used for braking the winch.

2. The sand vibration liquefaction simulation device according to claim 1, wherein The counterweight piece comprises: a counterweight block and a counterweight kettle, a plurality of the counterweight blocks are of a specified weight, and the inside of the counterweight kettle is provided with a cavity capable of adding different substances to change the overall weight of the counterweight kettle; the through hole comprises a first counterweight hole and a second counterweight hole arranged on the counterweight block and the counterweight kettle respectively.

3. The sand vibration liquefaction simulation device according to claim 1, wherein The brake mechanism comprises a brake bolt, a connecting block, a brake block and a plurality of brake pieces, the connecting block is arranged in the interior of the mounting seat, the brake bolt is threadedly connected with the connecting block, the brake block is rotationally connected with the connecting block, and one end of the brake bolt abuts against the brake block; the brake piece comprises a first friction piece arranged at the other end of the brake block and a second friction piece arranged on the mounting seat corresponding to the first friction piece, the first friction piece and the second friction piece are respectively located on two sides of the capstan, and the capstan rotates between the first friction piece and the second friction piece; when the brake bolt rotates and moves, the brake block can be pushed to rotate, the first friction piece is driven to approach the second friction piece, and the capstan is clamped.

4. The sand vibration liquefaction simulation device according to claim 1, wherein The guide hole is arranged on the support, the guide rod is arranged vertically on the counterweight platform, and the guide rod moves with the counterweight platform; the guide rod passes through the guide hole and moves along the opening direction of the guide hole.

5. A sand vibration liquefaction test method using the sand vibration liquefaction simulation device according to any one of claims 1 to 4, characterized by the steps of The method comprises: S1: a saturated sand soil sample is prepared in the box by a water sanding method, a pore water pressure gauge, a soil pressure gauge and an acceleration sensor are buried in the sand soil sample during the preparation process, a laser range finder is installed on the support, and an acceleration sensor is installed on the support plate; S2: the counterweight platform is adjusted to a suitable height by rotating the capstan, and the counterweight platform is fixed by the brake mechanism; subsequently, counterweight pieces corresponding to the required load for testing are added on the counterweight platform; S3: the sieve plate is laid on the upper surface of the saturated sand soil sample, then the capstan is driven to make the counterweight platform slowly descend, when the counterweight platform descends to contact the sieve plate, the connecting rope is disconnected from the counterweight mechanism, and the descending displacement of the counterweight platform is measured by the laser range finder; S4: after the counterweight platform is stable, the hydraulic motor is started to drive the eccentric block to rotate, the box and the saturated sand soil sample in the interior are vibrated, the vibration condition of sand soil liquefaction is simulated to make the sand soil sample liquefy, and the data of the pore water pressure gauge, the soil pressure gauge and the acceleration sensor before vibration, during vibration and after vibration when the pore water pressure is completely dissipated are recorded. S5: test the parameters of the sample under the load of F1, F2, F3, F4, …, F n respectively according to the above steps, wherein F1=0, the saturated sand sample cannot be liquefied due to excessive stress when the load is F n , the values of F2 to F n are in an arithmetic progression; and the required sand liquefaction characteristic data are obtained by calculation based on the measured parameters.

Images