Physical model test device and method for testing anti-pulling performance of non-soil-squeezing precast pile foundation

Abstract

The invention discloses a physical model test device and method for testing the anti-pulling performance of a non-soil-squeezing precast pile foundation. The method comprises the following steps that firstly, a model box is manufactured; secondly, a model pile is manufactured; step 3, filling soil; fourthly, the model pile is put in; fifthly, cement paste is injected into the bottom of the model pile for bottom sealing; sixthly, a grouting system and a vacuum drainage system are connected; seventhly, pile side grouting is conducted; 8, maintaining the grouting body; ninthly, a sensor and a jack are installed; 10, simulating underground water; and eleventhly, the anti-pulling performance of the large-diameter non-soil-squeezing precast pile is tested. Compared with the prior art, the device has the advantages that the device is low in manufacturing cost, easy and convenient to use, simple and convenient in machining technology, simple and safe in structure, convenient to carry and capable of being repeatedly used; the method has the advantages of high implementability, simple and clear design steps, safe and reliable execution process and high control precision, and can be suitable for various application scenes; the device can simulate the influence of soil layers with different physical properties, underground water flow velocity, position, number and diameter of grout outlets, different grouting processes and parameters such as static pressure grouting and high-pressure jet grouting, and different construction processes on the anti-pulling performance of the anti-pulling pile.

Description

Technical Field

[0001] The present invention relates to the technical field of pile foundations in building construction, and specifically to a physical model test device and method for testing the uplift performance of non-displacement precast pile foundations. Background Art

[0002] As a key component for resisting the uplift force of structures in foundation engineering, uplift piles are widely used in fields such as the anti-floating of large basements, the anti-wind and anti-seismic of tall buildings, the anti-wave load of offshore platforms, and the bridge anchorage system. With the acceleration of the urbanization process and the expansion of the scale of engineering structures, large-diameter non-displacement precast piles are gradually widely used in uplift foundations under complex geological conditions due to their high bearing capacity, small construction disturbance, and excellent environmental protection performance. However, the accurate testing and evaluation of their uplift performance still face many challenges, which directly affect the reliability and economy of engineering design.

[0003] After retrieval, for the patent synchronous static load test anchor pile reaction force system for compressive and uplift bearing capacity, publication number: CN215630219U, this patent tests the uplift performance of uplift piles by setting up a test device on the pile foundation at the construction site. Although on-site tests can reflect the actual working conditions, they are costly, have a long cycle, and are restricted by geological conditions, making it difficult to repeat and verify; in small-scale physical model experiments, the research on the influence of different soil layers on the uplift force is not deep enough.

[0004] The information disclosed in this background art section is only intended to increase the understanding of the overall background of the present invention, and should not be regarded as an admission or any form of implication that this information constitutes prior art already known to those of ordinary skill in the art. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the above technical defects and provide a physical model test device for testing the uplift performance of non-displacement precast pile foundations. This device has a low manufacturing cost, is easy to use, has a simple processing technology, is convenient, has a simple and safe structure, is relatively easy to carry, and can be reused; the present invention also provides a method for testing the uplift performance of large-diameter non-displacement precast piles. This method has high feasibility, the design steps are simple and clear, the execution process is safe and reliable, the control accuracy is high, and it can be applied to a variety of application scenarios. The present invention can simulate the influence of different physical properties of soil layers, underground water flow velocity, the position, quantity, and diameter of slurry outlets, different grouting processes and parameters such as static pressure grouting and high-pressure rotary jet grouting, and different construction processes on the uplift performance of uplift piles.

[0006] To solve the above problems, the technical solution of the present invention is: a physical model test device for testing the uplift performance of a non-displacement precast pile foundation, including model box side plates. Three of the model box side plates enclose a U shape. At the bottom between the three groups of model box side plates, there is a fixedly connected model box bottom plate. Each model box side plate is symmetrically provided with six water inlets and outlets. Between every two mutually spaced model box side plates, there is fixedly provided high-strength tempered glass. Inside the model box side plates, there are cobblestones. Above the three groups of model box side plates, there is a cross-shaped reaction frame; Model pile, the model pile is located between the model box side plates. The side of the model pile is provided with upper grouting holes and lower grouting holes. At the bottom of the model pile, there is a grouting pipe. At the bottom of the model pile, there is a permeable stone. At the lower part of the model pile, there are a plurality of strain gauges evenly spaced. At the bottom of the model pile, there are symmetrically provided two metal hooks. At the bottom of the model pile, there is injected cement slurry for bottom sealing. Inside the cement slurry bottom sealing, there are inserted five long screws. At the top of the model pile, there is a cover plate. The cover plate is connected to the long screws through nuts. At the upper end of the cover plate, there are short screws. The upper end of the short screws is connected with a steel plate. At the upper end of the cover plate, there are two dial gauges. Above the fill on both sides of the model pile, there are symmetrically provided four CMOS laser displacement gauges. The metal hooks are provided with tension sensors. At the upper end of the cross-shaped reaction frame, there is a jack. At the upper end of the jack, there is a pressure sensor; Medium-weathered bedrock layer, the medium-weathered bedrock layer is arranged on the upper end of the model box bottom plate. Above the medium-weathered bedrock layer, there is an aquifer. Inside the aquifer, there are symmetrically arranged two earth pressure cells and pore water pressure gauges. Above the aquifer, there is a hard soil layer. Above the hard soil layer, there is a soft soil layer; Grouting pipe, the grouting pipe is connected with a control valve, a pressure gauge, a pressure regulating valve, a slurry storage tank and a multi-functional cement grouting machine; Vacuum water extraction pipe, the vacuum water extraction pipe is connected with a control valve, a pressure gauge, a pressure regulating valve, a vacuum pump and a water storage tank.

[0007] Furthermore, a semi-circular steel barrel and a small circular steel barrel are inserted into the medium-weathered bedrock layer. After pulling out the semi-circular steel barrel and the small circular steel barrel, small circular holes are formed in the medium-weathered bedrock layer, and circular holes are formed between the other layers. Inside the small circular holes, there are steel reinforcement cages, and the model pile is located inside the circular holes.

[0008] Furthermore, the surface of the grouting pipe is provided with a control switch.

[0009] Furthermore, it also includes a manufacturing method of a physical model test device for testing the uplift performance of a non-displacement precast pile foundation, including the following steps: Step 1: Fabricate the model box. The length, width, and height of the model box are 1m, 0.5m, and 1.2m respectively. The bottom plate of the model box is a steel plate with a thickness of 3cm. Drill two holes with a diameter of 2cm at the center of the bottom plate of the model box. The four sides of the model box are composed of three side plates of the model box with a thickness of 3cm. Six water inlets and outlets with a diameter of 3cm are symmetrically arranged on each side plate of the model box. The front of the model box is a 3cm thick high-strength tempered glass. Lay a layer of cobblestones with a thickness of 3 - 5cm and a diameter of 1 - 2cm along the side plates of the model box. Place the cross reaction frame at the top of the model box aside for later use; Step 2: Fabricate the model pile. Select a polyvinyl chloride pipe with an outer diameter of 18cm, an inner diameter of 16cm, and a length of 0.75m as the model pile. Drill holes with a diameter of 1.5cm at 7cm and 50cm from the bottom of the model pile to simulate the upper grouting hole and the lower grouting hole. At the same time, drill two round holes with a diameter of 1.5cm at 56cm from the bottom and arrange the bladder bags to simulate the grouting pipes in the bladder bags. Drill holes at 15cm from the bottom and place permeable stones. Starting from 10cm from the lower end of the model pile, attach strain gauges every 15cm and seal them with AB glue. Symmetrically embed two metal hooks at the bottom of the model pile. Place the processed model pile aside for later use; Step 3: Fill the soil. Insert the semi-circular steel barrel and the small circular steel barrel. The first layer of soil layer simulates the moderately weathered bedrock layer, which is made of barite powder, sand, gypsum, and water in a certain proportion. Pour the prepared slurry into the model box and grout until the thickness reaches 20cm. After initial setting, pull out the semi-circular steel barrel and the small circular steel barrel and let it stand for more than [X] days. Then insert the semi-circular steel barrel again and fill the second layer of soil aquifer. When the thickness of the second layer of soil reaches 10cm, symmetrically arrange two earth pressure cells and pore water pressure gauges at 25cm from the side of the model line. Continue to fill the soil. After the filling thickness of the second layer of soil reaches 20cm, fill the third layer of soil hard layer and the fourth layer of soil soft layer. The thicknesses of the third and fourth layers of soil are both 20cm. The sensor arrangement is the same as the step of placing sensors in the second layer of soil, and they are all arranged at 10cm from the upper layer of soil; Step 4: Place the model pile. Pull out the semi-circular steel barrel. At this time, a round hole with a diameter of 20cm is formed in the soil, and the diameter of the round hole is larger than the diameter of the model pile. Place a small steel reinforcement cage in the small round hole, and then place the model pile into the round hole. The spacing between the model pile and the surrounding soil is 1cm. Install the cross reaction frame; Step 5: Inject cement slurry to seal the bottom of the model pile, fill it to 12 - 15cm from the bottom of the model pile, and insert five long screws with a length of 70cm into the cement slurry. The long screws penetrate 8cm into the cement slurry. After the cement slurry solidifies, install a cover plate on the top of the model pile and connect it to the long screws through nuts. The cover plate at the top of the pile and the cement slurry at the bottom of the pile sealing the inner cavity of the pipe pile are sealed. The cover plate is connected to the steel plate above the jack through four short screws; Step 6: Connect the grouting system and the vacuum drainage system. Connect the four grouting pipes to the control valve, pressure gauge, pressure regulating valve, slurry storage tank, and multi-functional cement grouting machine in sequence; connect the vacuum water extraction pipe to the control valve, pressure gauge, pressure regulating valve, vacuum pump, and water storage tank in sequence. Step 7: Grout the pile side. Start the multi-functional cement grouting machine and conduct conventional grouting through the upper grouting hole and the lower grouting hole to fill the pile-soil gap. Conduct high-pressure grouting through the high-pressure jet grouting pipe to spray the slurry into the hard soil layer. Conduct grouting into the bladder through the grouting pipe in the bladder to make the bladder expand and bulge into the soil layer. At the end of grouting, prepare the remaining slurry in the slurry storage tank into 70*70*70 concrete test blocks for standby. Step 8: Cure the grouted body. After the grouting is completed, both the grouted body and the 70*70*70 concrete test blocks in Step 7 are cured naturally for [X] days, and then conduct the strength test of the concrete test blocks. After reaching the specified strength, carry out the next test; otherwise, continue curing. Step 9: Install sensors and jacks. Arrange two dial gauges on the cover plate, symmetrically arrange four CMOS laser displacement gauges above the filled soil on both sides of the pile circumference, arrange a tension sensor on the metal hook at the bottom of the pile, place a jack, and arrange a pressure sensor above the jack. Step 10: Simulate groundwater. Connect the water inlet to an external water source. After the water flow rate at the drainage outlet reaches stability, the next step can be carried out. Step 11: Conduct the uplift performance test of large-diameter non-displacement precast piles. After the grouted body reaches a certain strength, conduct the static load test study of the uplift pile. Apply axial load through the axial jack, collect the loads on the upper and lower parts of the model pile through the upper pressure sensor and the lower tension sensor, collect the strain of the pile body through the strain gauges on the pile body, obtain the load-displacement curve (Q-S curve) of the static load test of the uplift pile, calculate the bearing capacity and side friction resistance of the pipe-jacking pile with follow-up casing, and obtain the displacement of the uplift pile and the displacement of the soil layer through the dial gauge and the CMOS laser displacement gauge respectively, so as to evaluate the contribution effect of different uplift measures on the uplift force.

[0010] The advantages of the present invention compared with the existing technology are as follows: The device of the present invention has low manufacturing cost, is easy to use, has simple and convenient processing technology, is simple and safe in structure, is relatively convenient to carry, and can be reused; the method in the present invention has high feasibility, the design steps are simple and clear, the execution process is safe and reliable, the control accuracy is high, and it can be applied to a variety of application scenarios. The present invention can simulate the influence of different physical properties of soil layers, underground water flow velocity, the position, quantity, and diameter of the slurry outlet, different grouting processes and parameters such as static pressure grouting and high-pressure jet grouting, and different construction processes on the uplift performance of uplift piles. Description of the Drawings

[0011] Figure 1It is a schematic diagram of the overall structure of the device of the present invention.

[0012] Figure 2 It is a schematic diagram of the structure of the bottom plate and side plate of the model box of the present invention.

[0013] Figure 3 It is a schematic diagram of the structure of the model pile of the present invention.

[0014] Figure 4 It is a schematic diagram of the structure of the semi-circular steel barrel and small circular steel barrel of the present invention.

[0015] Figure 5 It is a schematic diagram of the pouring structure of the moderately weathered bedrock layer of the present invention.

[0016] Figure 6 It is a schematic diagram of the structure of the water-containing soil layer, earth pressure cell, and water content sensor filled in the present invention.

[0017] Figure 7 It is a schematic diagram of the structure of the hard soil layer filled in the present invention.

[0018] Figure 8 It is a schematic diagram of the structure of the soft soil layer filled in the present invention.

[0019] Figure 9 It is a schematic diagram of the soil layer structure after the semi-circular steel barrel and small circular steel barrel are pulled out in the present invention.

[0020] Figure 10 It is a schematic diagram of the structure of placing the model pile, steel reinforcement cage, and installing the cross reaction frame in the present invention.

[0021] Figure 11 It is a schematic diagram of the structure of the cement slurry bottom seal, installation of the cover plate, and steel plate in the present invention.

[0022] Figure 12 It is a schematic diagram of the structure of connecting the grouting system and the vacuum drainage system in the present invention.

[0023] Figure 13 It is a schematic diagram of the pile side grouting structure in the present invention.

[0024] Figure 14 It is a schematic diagram of the structure of installing the sensor in the present invention.

[0025] Figure 15 It is a schematic diagram of the structure of the model pile and tempered glass in the present invention.

[0026] Figure 16 It is a schematic diagram of the top view structure of the model box of the present invention.

[0027] As shown in the figure: 1. Multifunctional cement grouting machine; 2. Slurry storage tank; 3. Pressure regulating valve; 4. Pressure gauge; 5. Control valve; 6. Vacuum pump; 7. Water storage tank; 8. Vacuum water suction pipe; 9. Grouting pipe; 10. Control switch; 11. Nut; 12. Short screw; 13. Cross reaction frame; 14. CMOS laser displacement meter; 15. Cover plate; 16. Cobblestone; 17. Grouting pipe; 18. Water inlet; 19. Upper grouting hole; 20. Long screw; 21. Pore water pressure gauge; 23. Strain gauge; 24. Permeable stone; 26. Steel reinforcement cage; 27. Small round hole; 28. Bottom plate of model box; 29. Tensile sensor; 30. Metal hook; 31. Side plate of model box; 32. Medium-weathered bedrock layer; 33. Lower grouting hole; 34. Cement slurry seal; 35. Aquifer; 36. High-pressure jet grouting pipe; 37. Hard soil layer; 38. Drainage port; 39. Earth pressure cell; 40. Soft soil layer; 41. Pocket; 42. Model pile; 43. Dial gauge; 44. Jack; 45. Steel plate; 46. High-strength tempered glass; 47. Semi-circular steel barrel; 48. Pressure sensor; 49. Small round steel barrel. Specific implementation mode

[0028] The following further illustrates the specific implementation mode of the present invention in conjunction with the attached drawings. Among them, the same components are denoted by the same reference numerals.

[0029] It should be noted that the terms "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to the directions in the drawings, and the terms "inner" and "outer" respectively refer to the directions towards or away from the geometric center of a specific component.

[0030] In order to make the content of the present invention easier to be clearly understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention.

[0031] As Figures 1 to 16 shown, the manufacturing method of the physical model test device for the uplift performance test of the large-diameter non-displacement precast pile foundation includes the following steps: Step 1, fabricate a model box. The length, width and height of the model box are 1m, 0.5m and 1.2m respectively. The bottom plate 28 of the model box is a 3-cm-thick steel plate. Two holes with a diameter of 2 cm are drilled in the center of the bottom plate 28 of the model box. The four sides of the model box are composed of three 3-cm-thick side plates 31 of the model box. Six water inlets 18 and drainage ports 38 with a diameter of 3 cm are symmetrically arranged on each side plate 31 of the model box. The front of the model box is a 3-cm-thick high-strength tempered glass 46. A layer of cobblestones 16 with a thickness of 3-5 cm and a diameter of 1-2 cm is laid along the side plates 31 of the model box. Place the cross reaction frame 13 at the top of the model box aside for later use; Step 2: Fabricate the model pile 42. Select a PVC pipe with an outer diameter of 18 cm, an inner diameter of 16 cm, and a length of 0.75 m as the model pile 42. Drill holes with a diameter of 1.5 cm at 7 cm and 50 cm from the bottom of the model pile 42 to simulate the upper grouting hole 19 and the lower grouting hole 33. At the same time, drill two circular holes with a diameter of 1.5 cm at 56 cm from the bottom and arrange the bladder 41 to simulate the grouting pipe 17 in the bladder 41. Drill a hole at 15 cm from the bottom and place the permeable stone 24. Starting from 10 cm from the lower end of the model pile 42, attach strain gauges 23 every 15 cm and seal them with AB glue. Symmetrically embed two metal hooks 30 at the bottom of the model pile 42. Place the processed model pile aside for standby; Step 3: Fill the soil and insert the semi-circular steel barrel 47 and the small circular steel barrel 49. The first layer of soil simulates the moderately weathered bedrock layer 32, which is made of barite powder, sand, gypsum, and water in a certain proportion. Inject the prepared slurry into the model box and grout until the thickness reaches 20 cm. After initial setting, pull out the semi-circular steel barrel 47 and the small circular steel barrel 49 and let it stand for more than 7 days. Then insert the semi-circular steel barrel 47 again and fill the second layer of soil aquifer 35. When the thickness of the second layer of soil reaches 10 cm, symmetrically arrange two earth pressure cells 39 and pore water pressure gauges 21 at 25 cm from the side of the model line. Continue to fill the soil. After the filling thickness of the second layer of soil reaches 20 cm, fill the third layer of soil hard layer 37 and the fourth layer of soil soft layer 40. The thicknesses of the third and fourth layers of soil are both 20 cm. The sensor arrangement is the same as the step of placing sensors in the second layer of soil, and they are all arranged at 10 cm from the upper layer of soil; Step 4: Place the model pile 42 and pull out the semi-circular steel barrel 47. At this time, a circular hole with a diameter of 20 cm is formed in the soil, and the diameter of the circular hole is larger than the diameter of the model pile 42. Place the small steel reinforcement cage 26 in the small circular hole 27, and then place the model pile 42 into this circular hole. The distance between the model pile 42 and the surrounding soil is 1 cm, and install the cross reaction frame 13; Step 5: Inject cement slurry to seal the bottom 34 of the model pile 42, fill it to 12 - 15 cm from the bottom of the model pile, and insert five long screws 20 with a length of 70 cm into the cement slurry. The long screws 20 penetrate 8 cm into the cement slurry. After the cement slurry solidifies, install a cover plate 15 on the top of the model pile 42, which is connected to the long screws 20 through nuts 11. The cover plate 15 at the pile top and the cement slurry at the bottom of the pile bottom embedded rock layer seal the inner cavity of the pipe pile. The cover plate 15 and the steel plate 45 above the jack 44 are connected by four short screws 12; Step 6: Connect the grouting system and the vacuum drainage system. Connect the four grouting pipes 9 to the control valve 5, pressure gauge 4, pressure regulating valve 3, slurry storage tank 2, and multi-functional cement grouting machine 1 in sequence; connect the vacuum water extraction pipe 8 to the control valve 5, pressure gauge 4, pressure regulating valve 3, vacuum pump 6, and water storage tank 7 in sequence. A control switch 10 is provided on the surface of the grouting pipe 9. Step 7: Side grouting of the pile. Start the multi-functional cement grouting machine 1, conduct conventional grouting through the upper grouting hole 19 and the lower grouting hole 33 to fill the pile-soil gap, conduct high-pressure grouting through the high-pressure jet grouting pipe 36 to spray the slurry into the hard soil layer, and conduct grouting of the bladder 41 through the grouting pipe 17 in the bladder 41 to make the bladder 41 expand and bulge into the soil layer. When the grouting is completed, prepare the remaining slurry in the slurry storage tank 2 into concrete test blocks of 70*70*70 for standby. Step 8: Curing of the grouting body. After the grouting is completed, both the grouting body and the 70*70*70 concrete test blocks in Step 7 are cured naturally for 28 days. Then, conduct strength testing on the concrete test blocks. After reaching the specified strength, carry out the next test; otherwise, continue the curing. Step 9: Install sensors and jacks. Arrange two dial gauges 43 on the cover plate 15, symmetrically arrange four CMOS laser displacement gauges 14 above the filled soil on both sides of the pile circumference, arrange a tension sensor 29 on the metal hook 30 at the bottom of the pile, place a jack 44, and a pressure sensor 48 is arranged above the jack 44. Step 10: Simulate groundwater. Connect the water inlet 18 to an external water source. After the water flow rate at the water outlet 38 reaches stability, the next step can be carried out. Step 11: Pull-out performance test of large-diameter non-displacement precast piles. After the grouting body reaches a certain strength, conduct a static load test study on the pull-out pile. Apply an axial load through the axial jack 44, collect the loads on the upper and lower parts of the model pile through the upper pressure sensor 48 and the lower tension sensor 29, collect the strain of the pile body through the strain gauges 23 on the pile body, obtain the load-displacement curve Q-S curve of the static load test of the pull-out pile, calculate the bearing capacity and side friction resistance of the pipe jacking pile following the drilling, and obtain the displacement of the pull-out pile and the displacement of the soil layer through the dial gauges 43 and the CMOS laser displacement gauges 14 respectively, so as to evaluate the contribution effect of different pull-out measures on the pull-out force.

[0032] All electrical components appearing in this article are electrically connected to an external main controller and 220V mains electricity. The main controller can be a conventional known device such as a computer for control. In the specific implementation manners of the present disclosure, detailed descriptions of known functions and known components are omitted. To ensure the compatibility of the equipment, all the adopted operating means are consistent with the parameters of market instruments.

[0033] The above describes the present invention and its embodiments. Such description is not restrictive. What is shown in the drawings is only one of the embodiments of the present invention, and the actual structure is not limited thereto. In summary, if those of ordinary skill in the art are inspired by it and, without departing from the spirit of the present invention, design similar structural modes and embodiments to this technical solution without creative efforts, they shall fall within the protection scope of the present invention.

Claims

1. A physical model test device for testing the pull-out performance of non-squeezed prefabricated pile foundation, characterized in that: include; Model box side panels (31), three of the model box side panels (31) are arranged in a U-shape, a model box bottom plate (28) is fixedly connected to the bottom between the three groups of model box side panels (31), each of the model box side panels (31) is symmetrically provided with six water inlets (18) and water outlets (38), high-strength tempered glass (46) is fixedly provided between two of the model box side panels (31) spaced apart from each other, and a cross reaction frame (13) is provided on the upper side between the three groups of model box side panels (31); A model pile (42), the model pile (42) being located between the side plates (31) of the model box, the side of the model pile (42) being provided with an upper grouting hole (19) and a lower grouting hole (33), the bottom of the model pile (42) being provided with a grouting pipe (17), the bottom of the model pile (42) being provided with a permeable stone (24), the bottom of the model pile (42) being provided with a plurality of evenly spaced strain gauges (23), the bottom of the model pile (42) being symmetrically provided with two metal hooks (30), the bottom of the model pile (42) being injected with cement slurry bottom seal (34), the cement slurry bottom seal (34) being inserted with five long screws (20), the A cover plate (15) is provided on the top of the model pile (42), the cover plate (15) is connected to the long screw (20) via a nut (11), a short screw (12) is provided on the upper end of the cover plate (15), a steel plate (45) is connected to the upper end of the short screw (12), two dial indicators (43) are provided on the upper end of the cover plate (15), four CMOS laser displacement meters (14) are symmetrically provided above the fill on both sides of the model pile (42), a tension sensor (29) is provided on the metal hook (30), a jack (44) is provided on the upper end of the cross reaction frame (13), and a pressure sensor (48) is provided on the upper end of the jack (44); A moderately weathered bedrock layer (32), the moderately weathered bedrock layer (32) being arranged at the upper end of the bottom plate (28) of the model box, an aquifer (35) being arranged at the upper end of the moderately weathered bedrock layer (32), two earth pressure boxes (39) and a pore water pressure gauge (21) being symmetrically arranged inside the aquifer (35), a PVC sleeve (25) being pre-buried in the middle of the moderately weathered bedrock layer (32) and the bottom end of the bottom plate (28) of the model box, a metal hook (30) being arranged inside the PVC sleeve (25), a hard soil layer (37) being arranged at the upper end of the aquifer (35), only earth pressure boxes (39) and a pore water pressure gauge (21) being symmetrically arranged inside the hard soil layer (37), a soft soil layer (40) being arranged at the upper end of the hard soil layer (37), and two groups of pebbles (16) being arranged inside the aquifer (35), the hard soil layer (37) and the soft soil layer (40); A grouting pipe (9), wherein the grouting pipe (9) is connected to a control valve (5), a pressure gauge (4), a pressure regulating valve (3), a grouting tank (2) and a multifunctional cement grouting machine (1); A vacuum water pumping pipe (8), wherein the vacuum water pumping pipe (8) is connected to a control valve (5), a pressure gauge (4), a pressure regulating valve (3), a vacuum pump (6) and a water storage tank (7).

2. According to claim 1, a physical model test device for testing the pull-out performance of non-squeezed prefabricated pile foundations is characterized by: A semicircular steel barrel (47) and a small circular steel barrel (49) are inserted into the middle weathered bedrock layer (32). The semicircular steel barrel (47) and the small circular steel barrel (49) are pulled out to form a small circular hole (27) in the middle weathered bedrock layer (32). Circular holes are formed between the remaining layers. A steel cage (26) is provided inside the small circular hole (27). The model pile (42) is located inside the circular hole.

3. According to claim 1, a physical model test device for testing the pull-out performance of non-squeezed precast pile foundations is characterized by: A control switch (10) is provided on the surface of the grouting pipe (9).

4. The method for manufacturing a physical model test device for testing the pull-out performance of a non-squeezed prefabricated pile foundation according to claims 1-3, characterized in that: The following steps are involved: Step 1, making a model box, the length, width and height of the model box are 1m, 0.5m and 1.2m respectively, the bottom plate (28) of the model box is a 3cm thick steel plate, two holes with a diameter of 2cm are drilled in the center of the bottom plate (28) of the model box, the four sides of the model box are composed of three 3cm thick model box side plates (31), each of the model box side plates (31) is symmetrically arranged with six water inlets (18) and drains (38) with a diameter of 3cm, the front of the model box is a 3cm thick high-strength tempered glass (46), a layer of pebbles (16) with a thickness of 3-5cm and a diameter of 1-2cm is laid along the side plates (31) of the model box, and the cross reaction frame (13) on the top of the model box is placed aside for standby; Step 2, making a model pile (42), selecting a polyvinyl chloride pipe with an outer diameter of 18 cm, an inner diameter of 16 cm, and a length of 0.75 m as the model pile (42), drilling holes with a diameter of 1.5 cm at 7 cm and 50 cm from the bottom of the model pile (42) to simulate the upper grouting hole (19) and the lower grouting hole (33), while drilling two circular holes with a diameter of 1.5 cm at 56 cm from the bottom and arranging a bag (41) to simulate the grouting pipe (17) in the bag (41), drilling holes at 15 cm from the bottom, placing permeable stones (24), attaching strain gauges (23) every 15 cm from 10 cm from the lower end of the model pile (42), and sealing with AB glue, symmetrically embedding two metal hooks (30) at the bottom of the model pile (42), and placing the treated model pile aside for use; Step 3: Fill soil. Insert the semicircular steel barrel (47) and the small circular steel barrel (49). The first soil layer simulates the medium-weathered bedrock layer (32). The medium-weathered bedrock layer (32) is made of barite powder, sand, gypsum, and water in a certain proportion. Inject the prepared mud into the model box until the thickness reaches 20 cm. After initial setting, pull out the semicircular steel barrel (47) and the small circular steel barrel (49) and let them stand for more than 7 days. Then insert the semicircular steel barrel (47) again to fill the second soil aquifer. (35), when the thickness of the second soil layer reaches 10 cm, two soil pressure boxes (39) and pore water pressure gauges (21) are symmetrically arranged 25 cm away from the side of the model line, and the soil is continued to be filled. When the thickness of the second soil layer reaches 20 cm, the third soil layer (37) and the fourth soil layer (40) are filled. The thickness of the third and fourth soil layers is 20 cm. The arrangement of sensors is consistent with the steps of placing sensors in the second soil layer, and they are all arranged 10 cm away from the previous soil layer; Step 4: Place the model pile (42) and pull out the semicircular steel barrel (47). At this time, a circular hole with a diameter of 20 cm is formed in the soil. The diameter of the circular hole is larger than the diameter of the model pile (42). A small steel cage (26) is placed in the small circular hole (27). Then, the model pile (42) is placed in the circular hole. The distance between the model pile (42) and the surrounding soil is 1 cm. The cross reaction frame (13) is installed. Step 5: inject cement slurry to seal the bottom (34) of the model pile (42) to a depth of 12-15 cm from the bottom of the model pile, and insert five long screws (20) with a length of 70 cm into the cement slurry. The long screws (20) penetrate 8 cm into the cement slurry. After the cement slurry solidifies, install a cover plate (15) on the top of the model pile (42) and connect it to the long screws (20) through nuts (11). The cover plate (15) on the top of the pile and the cement slurry seal (34) of the rock layer embedded in the bottom of the pile seal the inner cavity of the pipe pile. The cover plate (15) is connected to the steel plate (45) above the jack (44) through four short screws (12); Step 6: Connect the grouting system and the vacuum drainage system. Connect the four grouting pipes (9) to the control valve (5), the pressure gauge (4), the pressure regulating valve (3), the grouting tank (2) and the multifunctional cement grouting machine (1) in sequence; connect the vacuum water extraction pipe (8) to the control valve (5), the pressure gauge (4), the pressure regulating valve (3), the vacuum pump (6) and the water storage tank (7) in sequence; Step 7: Grouting on the pile side. Start the multifunctional cement grouting machine (1), perform conventional grouting through the upper grouting hole (19) and the lower grouting hole (33) to fill the gap between the pile and the soil. Perform high-pressure grouting through the high-pressure rotary jet grouting pipe (36) to spray the slurry into the hard soil layer. Perform grouting of the bag (41) through the grouting pipe (17) in the bag (41) to make the bag (41) expand and bulge and squeeze into the soil layer. When the grouting is completed, prepare the remaining slurry in the slurry storage tank (2) into a 70*70*70 concrete test block for standby use. Step 8: Grouting body curing. After the grouting is completed, the grouting body and the 70*70*70 concrete test block in step 7 are naturally cured for 28 days, and then the strength test of the concrete test block is carried out. After reaching the specified strength, the next step of the test is carried out, otherwise the curing is continued; Step 9: Install sensors and jacks. Arrange two dial indicators (43) on the cover plate (15), symmetrically arrange four CMOS laser displacement meters (14) above the backfill on both sides of the pile, arrange a tension sensor (29) on the metal hook (30) at the bottom of the pile, place a jack (44), and arrange a pressure sensor (48) above the jack (44); Step 10: Simulate groundwater, connect the water inlet (18) to an external water source, and after the water flow rate at the outlet (38) reaches a stable level, proceed to the next step; Step 11: Test the pull-out performance of large-diameter non-squeezed precast piles. After the grouting body reaches a certain strength, a static load test of the pull-out pile is carried out. An axial load is applied by an axial jack (44). The loads on the upper and lower parts of the model pile are collected by an upper pressure sensor (48) and a lower tension sensor (29). The strain of the pile body is collected by a pile body strain gauge (23). The load-displacement curve (QS curve) of the static load test of the pull-out pile is obtained. The bearing capacity and lateral friction resistance of the drilling and pipe pile are obtained by calculation. The displacement of the pull-out pile and the displacement of the soil layer can be obtained by a dial indicator (43) and a CMOS laser displacement meter (14), respectively, so as to judge the contribution of different pull-out measures to the pull-out force.

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