An experimental device for simulating soil constraint on pile foundation

Abstract

The present invention discloses an experimental device for simulating the restraining effect of soil on pile foundations, which belongs to the field of geotechnical engineering technology. It comprises a rectangular column, wherein the middle and lower parts of the columns are provided with a base plate fixed to the columns, a group of opposite ends of the base plate are symmetrically provided with a plurality of vertically spliced first hollow plates, and another group of opposite ends are closed, at least one group of light rods slidably connected thereto are provided on both ends of the first hollow plates, and the two ends of the light rods are fixed to the columns, a first elastic sealing film is provided inside the plurality of the first hollow plates, one end of the first elastic sealing film is fixed to the lower surface of the base plate, and the other end of the first elastic sealing film is fixed to the upper end surface of the column, and a first pressurizing mechanism is provided on the outer side of the first hollow plate. This technical solution is used to enhance the restraining effect of soil on pile foundations and the simulation effect of scenes, and to enhance the accuracy of pile foundation bearing capacity tests.

Description

Technical Field

[0001] The present invention relates to the field of geotechnical engineering technology, and in particular to an experimental device for simulating the constraint effect of soil on a pile foundation. Background Art

[0002] During geotechnical engineering construction, the design of pile foundations is particularly crucial. Pile foundations bear the primary load of the entire building's upper structure, and the interaction between the soil and the pile foundation enhances bearing capacity. Therefore, when experimentally studying pile bearing behavior, the soil's constraint on the pile foundation is a variable that must be considered.

[0003] Some devices have also appeared in the prior art for studying the relationship between the bearing capacity of pile foundations and soil constraints. For example, soil is placed in an experimental box, and the experimental pile foundation is buried in the soil. Then, through devices such as push rods, the soil layer is pressurized laterally to simulate the constraint force of the soil layer on the pile foundation, and then the bearing capacity experiment is carried out. However, in actual experiments, the design concept of the above-mentioned device is simple, and the form of simulating the soil layer constraint on the pile foundation is single, which is difficult to be equivalent to the effect and parameters of the soil constraint on the pile foundation in reality. Therefore, it is difficult to more accurately simulate the constraint effect of the soil on the pile. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide an experimental device for simulating the constraint effect of soil on pile foundations, so as to improve the constraint effect of soil on pile foundations and the simulation effect of scenes, and improve the accuracy of pile foundation bearing capacity tests.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides an experimental device for simulating the constraint effect of soil on pile foundation, comprising a rectangular column, a bottom plate fixed to the column in the middle and lower parts of the column, a plurality of vertically spliced first hollow plates symmetrically arranged on one group of opposite ends of the bottom plate, and another group of opposite ends closed, at least one group of light rods slidably connected thereto are provided on both ends of the first hollow plates, the two ends of the light rods are fixed to the column, a first elastic sealing film is provided inside the plurality of the first hollow plates, one end of the first elastic sealing film is fixed to the lower surface of the bottom plate, and the other end of the first elastic sealing film is fixed to the upper end surface of the column, A first pressurizing mechanism is provided on the outer side of the first hollow plate, and the first pressurizing mechanism includes a mounting frame, a linear motor, a transverse connecting plate, a plurality of vertical connecting plates and a plurality of top rods of different lengths. The two ends of the mounting frame are fixedly connected to the side surfaces of the column, the linear motor is fixed to the middle part of the mounting frame, and the output end of the linear motor is arranged toward the first hollow plate, the middle part of the transverse connecting plate is fixed to the output end of the linear motor, a plurality of the vertical connecting plates are evenly fixed on the transverse connecting plate, one end of a plurality of the top rods are fixed to the vertical connecting plate, and the other ends of a plurality of the top rods are evenly arranged on the outer surface of the first hollow plate.

[0007] The working principle of this technical solution is:

[0008] Fill the experimental soil above the bottom plate, bury the experimental pile foundation in the middle of the experimental soil, and then start the linear motors on both sides. By transferring the thrust of the linear motor to the top rod and then acting on the first hollow plate, the first hollow plate will move inward under the action of the top rod to squeeze the experimental soil, that is, the experimental soil will exert a constraint force on the pile foundation, and then act on the end of the pile foundation through the hydraulic mechanism arranged above, and then collect the stress conditions of the pile foundation through the sensor arranged on the pile foundation, and then analyze the influence of the soil layer constraint on the bearing capacity of the pile foundation. It is not difficult to understand that due to the different lengths of the top rods, the contact time of the first hollow plate is different, and the force exerted on the experimental soil by the first hollow plate at different top rods is different, that is, the constraint force on the pile foundation is different, that is, the device can simulate the constraint force of soil layers of different depths on the pile foundation, thereby improving the accuracy of the soil layer on the pile foundation bearing capacity test.

[0009] Furthermore, a plurality of vertically spliced second hollow plates are provided on the closed ends of the bottom plate, the number and position of the second hollow plates are arranged corresponding to the first hollow plates, and slide plates are symmetrically provided at both ends of the second hollow plate facing the first hollow plate, and a first spring is provided between the ends of the two slide plates located inside the second hollow plate. The benefit is that when the first hollow plate is squeezed inward, the slide plate will compress the spring toward the inside of the second hollow plate, avoiding interference. At the same time, the first spring can also drive the slide plate to reset after losing the force of the first hollow plate, thereby preventing the experimental soil from running out.

[0010] Furthermore, the outer side surface of the second hollow plate is provided with a second pressurizing mechanism, and the second pressurizing mechanism includes a symmetrically arranged first connecting block and a symmetrically arranged connecting rod, the first connecting block is slidably connected to the light rod, one end of the connecting rod is rotatably connected to the first connecting block, and the other end of the connecting rod is rotatably connected to the middle part of the second hollow plate. The benefit is that, with this arrangement, the first hollow plate moves, pushing the first connecting block to slide on the light rod, thereby causing the other end of the connecting rod to rotate toward the middle part of the bottom plate, and then applying a force to the second hollow plate, thereby achieving extrusion of the soil layer on that side, so that the soil layer can achieve four-way constraint on the pile foundation, further enhancing the constraint effect of the soil layer on the pile foundation.

[0011] Furthermore, the connecting rod is a telescopic rod, which is beneficial in that the setting of the telescopic rod can adjust the length, thereby adjusting the position of the connecting rod end on the light rod, thereby adjusting the contact time between the first hollow plate and the connecting rod, and thereby adjusting the force applied to the soil layer by different second hollow plates, that is, also adjusting the constraint force of the soil layer at different depths in this direction on the pile foundation. Of course, the telescopic rod needs to be limited after extension and contraction, which is the existing technology (the setting of pin holes and limit pins is sufficient).

[0012] Furthermore, a second spring is provided at the connection portion between the connecting rod and the second hollow plate, one end of the second spring is fixed to the end of the connecting rod, and the other end of the second spring is slidably connected to the light rod. The advantage is that the setting of the second spring ensures that a certain angle is formed between the symmetrically arranged connecting rod ends and the light rod, thereby improving the pushing effect of the first hollow plate (if the two connecting rod ends are flush, locking will occur); at the same time, the second spring can also drive the second hollow plate to reset after the force of the first hollow plate is lost.

[0013] Furthermore, a groove is provided on the surface of the second hollow plate in contact with the bottom plate, and a ridge is provided on the bottom plate. The groove is slidably engaged with the ridge. The benefit is that the sliding limit connection prevents the second hollow plate from rotating.

[0014] Furthermore, a second elastic sealing film is provided on each of the plurality of spliced second hollow plates, one end of the second elastic sealing film is fixed to the bottom plate, and the other end is fixed to the column. The advantage of this is that when the movement distances of the second hollow plates are inconsistent, the second elastic sealing film seals the gaps between adjacent second hollow plates. Of course, the length and width of the second elastic sealing film can be set according to actual conditions. Preferably, the second elastic sealing film should also cover the surface of the skateboard.

[0015] Furthermore, a threaded rod is provided on one end of the top rod connected to the vertical connecting plate, and a nut matching the threaded rod is provided on the vertical connecting plate. The advantage is that the threaded rod can adjust the distance between the top rod and the first hollow plate, thereby adjusting the restraint force on the pile foundation at different depths.

[0016] Furthermore, a pressure transmission plate is provided on the end of the push rod that contacts the first hollow plate, and the pressure transmission plate contacts the second hollow plate. A hollow sleeve is provided on the side surface of the pressure transmission plate facing the push rod, one end of the hollow sleeve is fixedly connected to the pressure transmission plate, and the other end is slidably connected to the push rod, and a third spring is provided between the pressure transmission plate and the end of the push rod. The benefit is that when the bearing force is applied to the pile foundation, the pile foundation will squeeze and compress the soil layer. However, due to the small volume of the experimental soil, after applying a certain torque compression, it has been compressed and is difficult to compress again. Therefore, it is difficult to simulate the situation where the pile foundation squeezes the soil layer, resulting in the soil layer being compressed. The setting of the third spring solves this problem. The stiffness of the third spring can be selected (or the stiffness can be adjusted by bolt extrusion) to determine the force of the spring compression, thereby simulating the degree of compression of the pile foundation on the soil layer, and further improving the experimental accuracy of the soil layer on the bearing capacity of the pile foundation (the stiffness requirement of the second spring can be adjusted on the other side).

[0017] The beneficial effects of the present invention are:

[0018] (1) The layered arrangement of several first hollow plates, combined with the use of different lengths of top rods, enables the device to simulate the constraint force of soil layers at different depths on the pile foundation. At the same time, the constraint force of soil layers at different depths only needs to be provided by one linear motor, which is ingenious and simplified. (2) The device can also achieve different forces on the soil layers on both sides by controlling the different strokes of the linear motors on both sides, and thus simulate the bearing conditions of the pile foundation when it is subjected to shear force. At the same time, due to the layered arrangement, only the length of the top rod needs to be adjusted to control the depth of the soil layer that generates the shear force, and thus simulate the influence of shear force generated at different depths on the bearing capacity of the pile foundation. (3) The setting of the connecting rod enables the device to drive the second hollow plate on the other side through the linear motor on one side to squeeze the soil layer, so that the soil layer can realize four-way constraint on the pile foundation, thereby improving the constraint effect of the soil layer on the pile foundation, that is, improving the experimental results of the pile foundation bearing test. 4) The setting of the nut and the screw can adjust the distance between the top rod and the first hollow plate, thereby facilitating the adjustment of the constraint force of soil layers of different depths on the pile foundation; (5) The linear motor applies different forces to simulate the constraint of different soil layers on the pile foundation, thereby realizing the analysis of the influence of different soil layers on the bearing capacity of the pile foundation. Therefore, the present invention can more accurately simulate the constraint effect of different soil bodies on the pile, solving the problem that it is difficult to accurately reconstruct the soil constraint due to spatial constraints and the difficulty in completely equivalence of soil parameters in actual experiments; (6) The connecting rod is set as a telescopic rod, which can not only adjust the force applied by the second hollow plate to the soil layer, but also adjust the position of the connecting rod end at the same height on the light rod, so that the squeezing force of the second hollow plate on the soil layer at the same height can be different, that is, the second hollow plate generates shear force on the pile foundation on one side, thereby simulating the influence of multi-directional shear force on the bearing capacity of the pile foundation.

[0019] Other advantages, objectives and features of the present invention will be described in the following description and will be apparent to those skilled in the art to some extent, or those skilled in the art can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to make the purpose, technical solutions and beneficial effects of the present invention more clear, the present invention provides the following drawings for illustration:

[0021] Figure 1 is a three-dimensional schematic diagram of the device of the present invention;

[0022] Figure 2 It is a schematic front view of the device of the present invention;

[0023] Figure 3 A schematic cross-sectional view of the front view of the device of the present invention;

[0024] Figure 4 is a schematic cross-sectional view of a top view of the device of the present invention;

[0025] Figure 5 For the present invention Figure 4 A partial enlarged schematic diagram of point A in the middle;

[0026] Figure 6 Schematic diagram of the connection between the third spring and the push rod in the device of the present invention;

[0027] Figure 7 Schematic diagram of the arrangement of pile foundation and experimental soil in the device of the present invention.

[0028] The following are marked in the accompanying drawings:

[0029] Column 1, base plate 2, first hollow plate 3, first elastic sealing film 4, third connecting block 5, polished rod 6, mounting frame 7, linear motor 8, transverse mounting 9, longitudinal mounting plate 10, pressure transmission plate 11, push rod 12, threaded rod 13, nut 14, first connecting block 15, connecting rod 16, second connecting block 17, second spring 18, second hollow plate 19, slide plate 20, first spring 21, fixing plate 22, hollow sleeve 23, third spring 24. DETAILED DESCRIPTION

[0030] like Figures 1 to 7 As shown, the present invention is an experimental device for simulating the constraint effect of soil on pile foundation, comprising a rectangular column 1, a bottom plate 2 fixed to the column 1 is provided in the middle and lower part of the column 1, a group of opposite ends on the bottom plate 2 are symmetrically provided with a plurality of vertically spliced first hollow plates 3, and the other group of opposite ends are closed, and at least one group of light rods 6 slidably connected thereto are provided on both ends of the first hollow plates 3, and the two ends of the light rods 6 are fixed to the column 1 through a third connecting block 5, and the interiors of the plurality of first hollow plates 3 are provided with a first elastic sealing film 4, which can be specifically made of natural latex (refer to the elasticity of a balloon), one end of the first elastic sealing film 4 is fixed to the lower surface of the bottom plate 2 through a fixing plate 22, and the other end of the first elastic sealing film 4 is fixed to the upper end surface of the column 1 on both sides, and the first A first pressurizing mechanism is provided on the outer side of a hollow plate 3, and the first pressurizing mechanism includes a mounting frame 7, a linear motor 8, a transverse connecting plate 9, a plurality of vertical connecting plates 10 and a plurality of top rods 12 of different lengths. The two ends of the mounting frame 7 are fixedly connected to the side of the column 1, the linear motor 8 is fixed to the middle of the mounting frame 7, and the output end of the linear motor 8 is arranged toward the first hollow plate 3, the middle part of the transverse connecting plate 9 is fixed to the output end of the linear motor 8, a plurality of vertical connecting plates 10 are evenly fixed on the transverse connecting plate 9, one end of a plurality of top rods 12 is fixed on the vertical connecting plate 10, and the other ends of the plurality of top rods 12 are evenly distributed on the outer surface of the first hollow plate 3. The evenly distributed arrangement here means that each first hollow plate 3 is provided with a top rod 12 opposite to it on the outside.

[0031] The working principle of this technical solution is:

[0032] Fill the experimental soil 25 above the bottom plate 2, bury the experimental pile foundation in the middle of the experimental soil 25, and then start the linear motors 8 on both sides. By transmitting the thrust of the linear motors 8 to the top rod 12, and then acting on the first hollow plate 3, the first hollow plate 3 will move inward under the action of the top rod 12 to squeeze the experimental soil 25, that is, the experimental soil 25 will exert a constraint force on the pile foundation, and then act on the end of the pile foundation through the hydraulic mechanism 26 set above, and then collect the stress conditions of the pile foundation through the sensors set on the pile foundation, and then analyze the effect of soil layer constraint on the pile foundation. It is not difficult to understand the influence of the bearing capacity of the foundation. Since the lengths of the top rods 12 are different, the time of contact with the first hollow plate is different, and the forces exerted on the experimental soil 25 by the first hollow plates at different top rods 12 are different, that is, the restraint forces on the pile foundation are different, that is, the device can simulate the restraint forces of soil layers of different depths on the pile foundation, thereby improving the accuracy of the soil layer bearing capacity test of the pile foundation. It should be noted that the first hollow plate 3 can be reset by fixing the end of the top rod 12, that is, the top rods 12 of different lengths only change the position of the first hollow plate 3 on the light rod 6.

[0033] The closed ends of the bottom plate 2 are each provided with a plurality of vertically spliced second hollow plates 19. The number and position of the second hollow plates 19 are set correspondingly to the first hollow plates 3. Slide plates 20 are symmetrically provided at both ends of the second hollow plates 19 facing the first hollow plates 3. A first spring 21 is provided between the ends of the two slide plates 20 located inside the second hollow plates 19. When the first hollow plate is squeezed inward, the slide plates 20 will compress the first spring 21 toward the inside of the second hollow plate to avoid interference. At the same time, the first spring 21 can also drive the slide plates 20 to reset after losing the force of the first hollow plate to prevent the experimental soil 25 from running out. In order to further improve the movement effect of the second hollow plate 19, a guiding light rod 6 can be set in the form of the first hollow plate 3, as long as it does not interfere with the experimental pile foundation.

[0034] The outer side surface of the second hollow plate 19 is provided with a second pressurizing mechanism, which includes a symmetrically arranged first connecting block 15 and a symmetrically arranged connecting rod 16. The first connecting block 15 is slidably connected to the light rod 6, and one end of the connecting rod 16 is rotatably connected to the first connecting block 15, and the other end of the connecting rod 16 is rotatably connected to the middle of the second hollow plate (of course, the two ends of the connecting rod 16 can also be rotatably connected). In this setting, the first hollow plate moves, pushing the first connecting block 15 to slide on the light rod 6, so that the other end of the connecting rod 16 rotates toward the middle of the bottom plate 2, and then applies a force to the second hollow plate, thereby realizing the extrusion of the soil layer on that side, so that the soil layer can realize four-way constraint on the pile foundation, further enhancing the constraint effect of the soil layer on the pile foundation.

[0035] The connecting rod 16 is a telescopic rod. The setting of the telescopic rod can adjust the length, and then adjust the position of the end of the connecting rod 16 on the light rod 6, and then adjust the contact time between the first hollow plate and the connecting rod 16, and then adjust the force applied to the soil layer by different second hollow plates, that is, it also adjusts the constraint force of the soil layer at different depths in this direction on the pile foundation. Of course, the telescopic rod needs to be limited after extension and contraction, which is the existing technology (the setting of pin holes and limit pins is sufficient).

[0036] A second spring 18 is provided at the connection portion between the connecting rod 16 and the second hollow plate 19. One end of the second spring 18 is fixed to the end of the connecting rod 16, and the other end of the second spring 18 is slidably connected to the polished rod 6 through the second connecting block 17. The setting of the second spring 18 ensures that a certain angle is formed between the symmetrically arranged ends of the connecting rod 16 and the polished rod 6, thereby enhancing the pushing effect of the first hollow plate (if the ends of the two connecting rods 16 are flush, locking will occur); at the same time, the second spring 18 can also drive the second hollow plate to reset after losing the force of the first hollow plate.

[0037] The second hollow plate 19 has a groove on its surface in contact with the bottom plate 2. The bottom plate 2 has a ridge. The groove is slidably engaged with the ridge, and the sliding limit connection prevents the second hollow plate from rotating.

[0038] A second elastic sealing film is provided on each of the plurality of spliced second hollow panels 19. One end of the second elastic sealing film is fixed to the base plate 2, and the other end is fixed to the column 1. When the movement distances of the second hollow panels are inconsistent, the second elastic sealing film seals the gaps between adjacent second hollow panels. Of course, the length and width of the second elastic sealing film can be set according to actual conditions. Preferably, the second elastic sealing film should also cover the surface of the slide plate 20.

[0039] A threaded rod 13 is provided on one end of the top rod 12 connected to the vertical connecting plate 10, and a nut 14 matching the threaded rod 13 is provided on the vertical connecting plate 10. The threaded rod 13 can adjust the distance between the top rod 12 and the first hollow plate, thereby adjusting the restraint force on the pile foundation at different depths.

[0040] A pressure transmission plate 11 is provided on the end of the mandrel 12 that contacts the first hollow plate. The pressure transmission plate 11 contacts the second hollow plate 19. A hollow sleeve 23 is provided on the side of the pressure transmission plate 11 facing the mandrel 12. One end of the hollow sleeve 23 is fixedly connected to the pressure transmission plate 11, and the other end is slidably connected to the mandrel 12. A third spring 24 is provided between the pressure transmission plate 11 and the end of the mandrel 12. When the bearing force is applied to the pile foundation, the pile foundation will squeeze and compress the soil layer. Since the volume of the experimental soil 25 is small, After a certain torque is applied to compress the soil, it has been compressed densely and is difficult to compress again. Therefore, it is difficult to simulate the situation where the pile foundation squeezes the soil layer, causing the soil layer to be compressed. The setting of the third spring 24 solves this problem. The stiffness of the third spring 24 can be selected (or the stiffness can be adjusted by bolt extrusion) to determine the force of the spring compression, thereby simulating the degree of compression of the pile foundation on the soil layer, and further improving the experimental accuracy of the soil layer's bearing capacity on the pile foundation (the stiffness requirement of the second spring 18 can be adjusted on the other side to achieve this).

[0041] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. An experimental device for simulating the constraint effect of soil on pile foundations, comprising rectangular columns with a bottom plate fixed to the columns at the middle and lower portions thereof, characterized in that: The lifting mechanism comprises a lifting mechanism, a lifting mechanism, a lifting mechanism being a lifting mechanism, a lifting mechanism being a lifting mechanism, a lifting mechanism being a lifting mechanism, a lifting mechanism being a lifting mechanism, a lifting mechanism being a lifting mechanism; ... being a lifting mechanism; a lifting mechanism being a lifting mechanism being a lifting mechanism; a lifting mechanism being a lifting mechanism being a lifting mechanism; a lifting mechanism being a lifting mechanism being a lifting mechanism; a lifting mechanism being a lifting mechanism being a lifting mechanism; a lifting mechanism being a lifting mechanism being a lifting mechanism; a lifting mechanism being a lifting mechanism being a lifting mechanism; a lifting mechanism being a lifting mechanism being a lifting mechanism; a lifting mechanism The closed ends of the bottom plate are each provided with a plurality of vertically spliced second hollow plates, the number and position of the second hollow plates are set corresponding to those of the first hollow plate, and the second hollow plate is symmetrically provided with slides at both ends facing the first hollow plate, and a first spring is provided between the ends of the two slides located inside the second hollow plate; the outer side surfaces of the second hollow plate are each provided with a second pressurizing mechanism, and the second pressurizing mechanism includes a symmetrically arranged first connecting block and a symmetrically arranged connecting rod, the first connecting block is slidably connected to the light rod, one end of the connecting rod is rotatably connected to the first connecting block, and the other end of the connecting rod is rotatably connected to the middle part of the second hollow plate.

2. The experimental device for simulating soil constraint on pile foundation according to claim 1, characterized in that: The connecting rod is a telescopic rod.

3. The experimental device for simulating soil constraint on pile foundation according to claim 1, characterized in that: A second spring is provided on the connection portion between the connecting rod and the second hollow plate. One end of the second spring is fixed on the end of the connecting rod, and the other end of the second spring is slidably connected to the polished rod.

4. The experimental device for simulating soil constraint on pile foundation according to claim 1, characterized in that: A groove is provided on the surface of the second hollow plate that contacts the bottom plate, and a ridge is provided on the bottom plate. The groove is slidably engaged with the ridge.

5. The experimental device for simulating soil constraint on pile foundation according to claim 1, characterized in that: A second elastic sealing film is provided on each of the plurality of spliced second hollow plates. One end of the second elastic sealing film is fixed to the bottom plate, and the other end is fixed to the column.

6. The experimental device for simulating soil constraint on pile foundation according to claim 1, characterized in that: A threaded rod is provided on one end of the top rod connected to the vertical connecting plate, and a nut matching the threaded rod is provided on the vertical connecting plate.

7. The experimental device for simulating soil constraint on pile foundation according to claim 6, characterized in that: A pressure transmission plate is provided on the end of the push rod that contacts the first hollow plate, and the pressure transmission plate contacts the second hollow plate. A hollow sleeve is provided on the side of the pressure transmission plate facing the push rod, one end of the hollow sleeve is fixedly connected to the pressure transmission plate, and the other end is slidably connected to the push rod, and a third spring is provided between the pressure transmission plate and the end of the push rod.

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