A reinforced soil foundation bearing capacity test device and test method

Abstract

The present invention discloses a reinforced soil foundation bearing capacity test device and a test method. The test device includes a bearing plate, a water tank, a jack, a load cell, and a static data collector. A groove rail is provided under the steel plate at the bottom of the water tank and is connected to the top of the jack. The other end of the jack is connected to the load cell and then to the bearing plate. A displacement sensor is installed on the bearing plate. By changing the diameter of the bearing plate, the distance between the bearing plates, and the layout of the reinforcement materials in the sand, the influence effects on the foundation bearing capacity and the interference effect are analyzed. It can be used to solve the problem that the in-situ test surcharge method in the current plate load test is relatively troublesome and costly, and can also be used to study the interference effect of the bearing capacity of the reinforced soil sand foundation.

Description

Technical Field

[0001] A test device and method for the bearing capacity of reinforced soil foundation of the present invention belong to the technical field of research on reinforced soil foundation. Background Technique

[0002] The design of foundation includes two parts: foundation soil and foundation. The design of foundation soil mainly includes the determination of the bearing capacity of foundation soil, the calculation of foundation settlement and the calculation of foundation stability, and the bearing capacity of foundation soil is the key to foundation design.

[0003] The plate load test is a test method to simulate the working performance of a building under vertical load. The foundation soil of the plate is not disturbed, and the test results are accurate and reliable. It is the main method used by countries around the world to determine the bearing capacity of foundation soil.

[0004] At present, the loads applied in the plate load test are generally sandbags and precast concrete blocks. The whole process of handling, stacking and unloading is rather troublesome, wasting manpower and increasing the test cost.

[0005] At present, the research on the bearing characteristics of reinforced soil foundation by domestic and foreign scholars mostly focuses on indoor model tests of single foundation action, which have size effects, boundary effects, etc., and also ignore the research on the interference effects that may exist when the foundations are adjacent to each other in actual engineering. Summary of the Invention

[0006] In order to overcome the deficiencies of the prior art, the present invention provides a test device and method for the bearing capacity of reinforced soil foundation to solve the problems of high test loading cost, time-consuming and laborious in the prior art.

[0007] The present invention is realized through the following technical solutions:

[0008] A test device for the bearing capacity of reinforced soil foundation includes a load-bearing plate, a water tank, a jack, a displacement sensor, a load cell, and a static data collector. The water tank is filled with water. The bottom of the water tank is connected to a jack. A load cell is arranged below the jack. The load cell is arranged on the load-bearing plate. The load-bearing plate is placed on the reinforced soil foundation. A displacement sensor is also arranged on the load-bearing plate. The displacement sensor is connected to a static data collector. A groove rail is arranged at the bottom of the water tank. The top of the jack is movably connected to the groove rail.

[0009] The groove rail includes two linear rails and a circular rail. The two linear rails intersect at the center of the bottom of the water tank. The number of circular rails is two to four, and the centers of the circular rails are all at the center of the bottom of the water tank.

[0010] Scales and limit holes are arranged on the groove rail, and angles are marked on the outer side of the circular rail.

[0011] The water tank is cylindrical.

[0012] Four jacks are provided at the bottom of the water tank.

[0013] A waterproof tarpaulin is provided on the inner wall of the water tank.

[0014] A drain faucet is also provided at the bottom of the water tank.

[0015] The bearing plate is formed by connecting a standard bearing plate or a large-diameter bearing plate and a small-diameter bearing plate. The bearing plate is provided with air holes and bolt holes, and the bearing plate is installed on the reinforced soil foundation by passing bolts through the bolt holes.

[0016] The bearing plate includes various diameter sizes.

[0017] A method for conducting a bearing capacity test on a reinforced soil foundation using the said device includes the following steps:

[0018] 1) Level the test surface of the sandy soil foundation;

[0019] 2) Assemble the test device. Place the bearing plate on the reinforced soil foundation, install the displacement sensor on the bearing plate, and connect it to the static data acquisition instrument. Arrange a load cell in the middle between the centroid of the bearing plate and the lower end of the jack, and then connect the whole to the bottom steel plate of the water tank. Place the jacks in the groove slide rails, adjust the positions of multiple jacks to be equidistant from the center of the bottom steel plate of the water tank, so that the distance between the bearing plates is the envisaged working condition; Assemble the water tank and lay a waterproof tarpaulin in the water tank;

[0020] 3) Load. Inject water into the water tank, and observe the load value collected by the static data acquisition instrument in real time. When the graded loading value is reached, observe that the displacement value no longer changes or stop injecting water for 5 minutes, and then read and record the load at this level and the current displacement;

[0021] 4) Change the diameter of the bearing plate, the distance between the bearing plates, and the layout of the reinforced material in the sandy soil, and repeat steps 1)-3) to analyze the influence of different conditions on the bearing capacity of the foundation and the interference effect; During the process of changing the distance between the bearing plates, the intersection of the diagonal connecting lines of the jacks in the groove slide rails is always the center of the circle.

[0022] 5) After the test is completed, drain the water through the drain faucet at the bottom of the water tank.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention can solve the problems that the in-situ test stacking method of the flat plate load test is relatively troublesome and costly at the present stage. In addition, it can also be used to study the interference effect of the bearing capacity of the reinforced soil sandy soil foundation.

[0025] The water tank of the present invention is cylindrical, and the circumference of the cylinder is composed of arc-shaped steel plates. There is a groove slide rail under the circular bottom steel plate, which is connected to the top of the jack. The other end of the jack is connected to the force measuring ring and is in contact with the bearing plate. The displacement sensor is installed on the bearing plate. A waterproof tarpaulin is laid in the water tank, and the water tank is filled with water. By changing the diameter of the bearing plate, the distance of the bearing plate, and the layout of the reinforcement materials in the sand, the influence effects on the bearing capacity of the foundation and the interference effect can be analyzed. In this device, the water tank is used to hold water, replacing concrete blocks and sandbags, saving time and effort and reducing the test cost. Moreover, the water tank is convenient to disassemble and transport. This water tank is convenient to disassemble, simple to operate, and can greatly reduce the test cost. Description of the Drawings

[0026] Figure 1 It is a schematic structural diagram of the test device of the present invention;

[0027] Figure 2 It is a schematic bottom view structural diagram of the water tank bottom steel plate of the present invention;

[0028] Figure 3 It is a schematic diagram of the position of the square-distributed jacks in the groove slide rail of the present invention;

[0029] Figure 4 It is a schematic diagram of the position of the rectangular-distributed jacks in the groove slide rail of the present invention;

[0030] Figure 5 It is a schematic structural diagram of the groove slide rail of the present invention;

[0031] Figure 6 It is a schematic structural diagram of the small-diameter bearing plate of the present invention;

[0032] Figure 7 It is a schematic structural diagram of the standard bearing plate of the present invention;

[0033] Figure 8 It is a schematic structural diagram of the large-diameter bearing plate of the present invention;

[0034] Figure 9 It is a schematic diagram of the connection method between the small-diameter bearing plate and the standard-diameter bearing plate of the present invention.

[0035] In the figure, 1, water; 2, water tank; 3, drain faucet; 4, groove slide rail; 5, jack; 6, force measuring ring; 7, displacement sensor; 8, bearing plate; 9, bolt hole; 10, reinforced soil foundation; 11, static data collector; 12, air hole; 13, bolt; 14, limit hole; 15, small-diameter bearing plate; 16, standard bearing plate 16; 17, large-diameter bearing plate; 41, linear slide rail; 42, annular slide rail. Detailed Embodiments

[0036] The following further elaborates on the present invention in conjunction with specific embodiments. However, the protection scope of the present invention is not limited to these embodiments. Any changes or equivalent substitutions that do not deviate from the concept of the present invention are included within the protection scope of the present invention.

[0037] A reinforced soil foundation bearing capacity test device includes a bearing plate 8, a water tank 2, a jack 5, a displacement sensor 7, a load cell 6, and a static data collector 11. The water tank 2 is filled with water. A waterproof tarpaulin is provided on the inner wall of the water tank 2, and a drain faucet 3 is provided at the bottom of the water tank 2.

[0038] The bottom of the water tank 2 is connected to a jack 5. A load cell 6 is provided below the jack 5. The load cell 6 is disposed on the bearing plate 8, and the bearing plate 8 is placed on the reinforced soil foundation 10. A displacement sensor 7 is also provided on the bearing plate 8, and the displacement sensor 7 is connected to a static data collector 11. A groove rail 4 is provided at the bottom of the water tank 2, and the top of the jack 5 is movably connected to the groove rail 4. Four jacks 5 are provided at the bottom of the water tank 2.

[0039] The water tank 2 is cylindrical, with a circular steel plate as the bottom surface and an arc-shaped steel plate as the side wall. A groove rail is provided under the circular steel plate at the bottom surface to be adapted to the top of the jack. The distance between the bearing plates is adjusted by moving the position of the jack within the groove rail.

[0040] The groove rail 4 includes two linear rails 41 and a circular rail 42. The two linear rails 41 intersect at the center of the bottom of the water tank 2. The number of the circular rails 42 is two to four, and the centers of the circular rails are all located at the center of the bottom of the water tank.

[0041] Limit holes 14 are opened at set positions on the groove rail. Multiple limit holes are provided on each groove rail to prevent the jack from moving to both sides after its position is fixed.

[0042] The layout of the groove rails at the bottom of the water tank is as follows: One is a linear rail along two diameters perpendicular to each other passing through the center of the circle, and there are also three concentric circular rails intersecting and connecting with the two linear rails.

[0043] Scales are marked on the outer side of the linear groove rail at the bottom of the water tank, and the distance of the bearing plate from the center of the circle can be directly read. The distance between the bearing plates can be obtained through calculation.

[0044] Angles are marked on the outer side of the circular groove rail at the bottom of the water tank. The two linear rails divide the circular steel plate at the bottom surface into four parts, and each part is marked with angles of 0° - 90° in the clockwise direction. The angle formed by the position of the bearing plate and the intersection point of the linear and circular rails can be directly read. The distance between the bearing plates can be obtained through calculation.

[0045] The bearing plate 8 is provided with air holes 12 and bolt holes 9, and the bearing plate 8 is placed on the reinforced soil foundation 10 through bolts 13 inserted into the bolt holes 9. The standard bearing plate and the large-diameter bearing plate are additionally provided with air holes at the periphery to avoid the generation of air flow during use and affect the bearing pressure balance.

[0046] The bearing plate 8 includes various diameter sizes: small-diameter bearing plate 15 (200mm), standard bearing plate 16 (300mm), large-diameter bearing plate 17 (400mm). The standard bearing plate or the large-diameter bearing plate overlaps and connects with the small-diameter one. The connection methods include:

[0047] 1) The bearing plates with adjacent diameters can be directly fixedly connected.

[0048] 2) Four bolt holes are evenly arranged on the small-diameter bearing plate. Four bolt holes on the standard bearing plate and the large-diameter bearing plate coincide with those on the small-diameter bearing plate. The standard bearing plate or the large-diameter bearing plate can be fixedly connected with the small bearing plate through bolts, and then the standard bearing plate or the large-diameter bearing plate is placed on the reinforced soil foundation 10.

[0049] 3) The small-diameter bearing plate can also be directly placed on the reinforced soil foundation 10. When the small-diameter bearing plate acts on the sandy soil foundation, the bolt holes can also be used as air holes to avoid the generation of air flow during use and affect the bearing pressure balance.

[0050] The method for conducting the bearing capacity test of the reinforced soil foundation using the said device includes the following steps:

[0051] Install the test device. The displacement sensor is installed on the small-diameter bearing plate. The centroid of the bearing plate is connected to the lower end of the jack, and then the whole is connected to the bottom steel plate of the water tank. The jack is placed in the groove slide rail, and the positions of the four jacks are adjusted to be equal in distance from the center of the bottom steel plate.

[0052] If the distance between one bearing plate and the two adjacent bearing plates on both sides is equal, that is, the four bearing plates are distributed in a square, then slide the four jacks in the linear slide rail, read the distance R' from the center of the bottom steel plate, and the side length of the square formed by the centroids of the four bearing plates is .

[0053] If the distance between one bearing plate and the two adjacent bearing plates on both sides is not equal, that is, the four bearing plates are distributed in a rectangle, then place two jacks at the intersection of the circular slide rail and the linear slide rail, and the other two jacks ensure that the connecting line passes through the center and slide on the circular slide rail. Read the distance from the center as R i , and the angle θ formed by its position, the intersection of the two tracks, and the center of the circle, then the side lengths of the rectangle formed by the centroids of the four bearing plates can be calculated according to the following formula.

[0054]

[0055] The jack slides to the set position of the groove slide rail, and a limit rod is inserted into the limit hole to fix the jack so that it does not slide to both sides.

[0056] Assemble the water tank. The bottom surface is a circular steel plate with a radius of 2 m, the height of the cylinder is 2 m, and a waterproof tarpaulin is laid inside the water tank. When the water tank is filled with water, the applied load is 25 tons. Here, the large-diameter bearing plate is 400 mm in diameter, and the bearing capacity of the sandy soil foundation is generally small, that is, the applied load can meet the surcharge requirements of the plate load test of the sandy soil foundation.

[0057] Load by injecting water into the water tank, and observe the load and displacement settlement values in real time. The loading levels of the foundation load test should not be less than 8 levels. Control the water injection speed evenly. When the graded loading value is reached, after observing that the displacement value no longer changes or stopping the water injection for 5 minutes, read and record the load at this level and the current displacement.

[0058] When the soil around the bearing plate is significantly extruded laterally or the settlement value increases rapidly, that is, the load-settlement (p-s) curve shows a steep drop section, the water injection and loading can be stopped.

[0059] After the loading is completed, drain the water in the water tank through the drain faucet.

[0060] Repeat the above steps, and the distance between the bearing plates and adjacent bearing plates, the diameter of the bearing plate, and the layout of the reinforcing materials in the sandy soil can be changed, including influencing factors such as the number of reinforcement layers, the length of reinforcement, the buried depth of the first-layer reinforcement, and the spacing of the lower-layer reinforcement, etc., to analyze their influence on the bearing capacity of the foundation and the interference effect.

[0061] According to the present invention, it can be used to solve the problem that the in-situ test surcharge method of the current plate load test is relatively troublesome and costly. In addition, it can also be used to study the interference effect of the bearing capacity of the reinforced soil sandy soil foundation.

[0062] The present invention will not be limited to the embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for conducting a bearing capacity test of a reinforced soil foundation using a reinforced soil foundation bearing capacity test device, characterized in that, The test device comprises a pressure plate (8), a water tank (2), a jack (5), a displacement sensor (7), a force ring (6), and a static data acquisition instrument (11); the water tank (2) contains water (1); a groove slide rail (4) is arranged at the bottom of the water tank (2); the top of the jack (5) is movably connected to the groove slide rail (4); a force ring (6) is arranged below the jack (5); the force ring (6) is arranged on the pressure plate (8); the pressure plate (8) is placed on a reinforced soil foundation (10); a displacement sensor (7) is also arranged on the pressure plate (8); and the displacement sensor (7) is connected to the static data acquisition instrument (11); a drainage tap (3) is also arranged at the bottom of the water tank (2); The groove slide rail (4) comprises two linear slide rails (41) and an annular slide rail (42), the two linear slide rails (41) intersect at the bottom center of the water tank (2), the number of the annular slide rails (42) is two to four, and the center of the annular slide rails is located at the bottom center of the water tank; the groove slide rail (4) is provided with scales and limit holes (14), and the outer side of the annular slide rail (42) is marked with an angle; The water tank (2) is cylindrical; four jacks (5) are arranged at the bottom of the water tank (2); the pressure plate (8) is formed by connecting a standard pressure plate (16) or a large-diameter pressure plate (17) with a small-diameter pressure plate (15); air holes (12) and bolt holes (9) are arranged on the pressure plate (8); the pressure plates (8) are overlapped and connected by bolts (13) inserted into the bolt holes (9), and are placed on a reinforced soil foundation (10); The following steps are involved: 1) Pressure plates with adjacent diameters are directly fixed and connected; 2) 4 bolt holes are evenly arranged on the small-diameter pressure plate, and 4 bolt holes are arranged on the standard pressure plate and the large-diameter pressure plate to overlap with the small-diameter pressure plate. The standard pressure plate or the large-diameter pressure plate can be fixedly connected with the small pressure plate by bolts, and then the standard pressure plate or the large-diameter pressure plate is placed on the reinforced soil foundation (10); 3) The small-diameter pressure plate can also be directly placed on the reinforced soil foundation (10). When the small-diameter pressure plate acts on the sandy soil foundation, the bolt holes are used as air holes to avoid airflow during use, which affects the pressure balance. The method for carrying out a reinforced soil foundation bearing capacity test using the device comprises the following steps: Install the test device; install the displacement sensor on the small diameter pressure plate, connect the centroid of the pressure plate to the lower end of the jack, and then connect the whole to the steel plate on the bottom of the water tank, place the jack in the groove slide rail, and adjust the positions of the four jacks to be equal to the center of the bottom steel plate; If the distance between a bearing plate and the two adjacent bearing plates on both sides is equal, that is, the four bearing plates are distributed in a square, slide the four jacks in the linear slide rail and read the distance R' from the center of the bottom steel plate. Then the side length of the square formed by the centroids of the four bearing plates is ; If the distances between a bearing plate and the two adjacent bearing plates on both sides are not equal, that is, the four bearing plates are rectangularly distributed, then place two jacks at the intersection of the circular slide rail and the linear slide rail, and ensure that the connecting line of the other two jacks passes through the center of the circle and slides on the circular slide rail; read the distance from the center of the circle as R i , and the angle formed by its position and the intersection of the two tracks and the center of the circle is θ, then the side lengths of the rectangle formed by the centroids of the four bearing plates can be calculated according to the following formula; Slide the jack to the set position of the groove slide rail, and insert the limit rod into the limit hole to fix the jack so that it does not slide to both sides; Assemble the water tank and lay the waterproof tarpaulin inside the water tank; Loading, pour water into the water tank, and observe the load and displacement settlement values in real time; the loading level of the foundation load test should not be less than 8 levels, and the water injection speed should be controlled to be uniform. When the graded loading value is reached, the displacement value is observed to no longer change or the water injection is stopped for 5 minutes, read and record the load and current displacement of that level; When obvious lateral extrusion of the soil around the bearing plate or a sharp increase in the settlement value occurs, that is, when a steep drop section appears in the load-settlement p-s curve, the water injection and loading can be stopped; After the loading is completed, drain the water in the water tank through the drain faucet; Repeat the above steps, change the distance between the bearing plate and the adjacent bearing plate, the diameter of the bearing plate, and the layout of the reinforcement material in the sand, including: the number of reinforcement layers, the reinforcement length, the burial depth of the first layer of reinforcement, and the spacing of the lower layer of reinforcement, and analyze its influence on the bearing capacity of the foundation and the interference effect.

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