In-situ testing device for soil compaction effect of prefabricated pile group
By using a modular precast pile group soil squeezing effect in-situ testing device, employing rotating test unit components and strain sensors, the problem of accurately assessing the soil squeezing effect in existing technologies has been solved. This enables comprehensive monitoring of soil squeezing characteristics and squeezing range, improving the accuracy and reliability of the test.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-22
- Publication Date
- 2026-03-06
AI Technical Summary
Existing technologies struggle to accurately assess the soil squeezing effect during the penetration of precast pile foundations, especially in large-area pile group construction. Sensor installation is complex, making it difficult to obtain accurate soil squeezing pressure data and hindering comprehensive monitoring of soil squeezing characteristics and the extent of soil squeezing.
A modular in-situ testing device for the soil squeezing effect of precast pile groups is designed. It adopts several rotating test unit components, each equipped with a strain sensor and a torque handle. It can be detachably inserted into the soil to test the soil squeezing effect. The strain sensor detects the soil squeezing pressure, and the torque handle enables the rotation and disassembly of the unit components.
It enables direct measurement of soil squeezing characteristics and pressure testing of soil in different directions within the squeezing range, improving the comprehensiveness and accuracy of soil squeezing effect testing and supporting long-term monitoring of single pile and pile group penetration processes.
Smart Images
Figure CN223974626U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of soil squeezing effect testing technology, and in particular to an in-situ testing device for the soil squeezing effect of precast pile groups. Background Technology
[0002] Soil squeezing effect in pile foundations is a construction impact caused by the compression of soil during the penetration of precast piles. This effect not only affects the safety of surrounding building foundations and nearby pipelines, but excessive squeezing can also severely impact the quality of pile foundation construction. This is especially true in large-area pile group construction, where the squeezing effect can be further amplified, making it a critical concern in pile foundation construction. Reasonable assessment of the soil squeezing effect during pile penetration and real-time monitoring of the soil squeezing status are essential for high-quality pile foundation construction.
[0003] Currently, the assessment of soil squeezing effect during precast pile penetration mainly relies on measurements using in-situ embedded inclinometers and earth pressure cells. However, due to the complexity of sensor drilling and installation, it is difficult to obtain accurate data on pile foundation soil squeezing pressure. Only indirect assessment of the squeezing effect can be achieved through soil deformation obtained from the inclinometers. There is an urgent need in engineering for a direct pile foundation soil squeezing effect testing device. This device should meet the following functions: firstly, it should be able to measure the compression characteristics of soil under different soil squeezing deformation conditions, allowing for a reasonable analysis of the soil's resistance characteristics under these conditions; secondly, it should be able to test and monitor the soil squeezing pressure in different directions throughout the entire squeezing range during the penetration of single piles and pile groups, enabling a comprehensive assessment of the soil squeezing effect.
[0004] To achieve the above functions, a prefabricated pile group soil displacement effect in-situ testing device is proposed. The device is a modular assembly structure that can penetrate into the soil to conduct soil displacement effect tests according to different testing requirements. After the test is completed, it can be disassembled and recycled. Utility Model Content
[0005] In order to overcome the above-mentioned shortcomings in the prior art, this utility model provides an in-situ testing device for the soil squeezing effect of precast pile groups, which can complete the corresponding tests of soil squeezing test method and pile group soil squeezing effect test method through the in-situ testing device for the soil squeezing effect of precast pile groups, thereby improving the comprehensiveness of soil squeezing effect testing.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] An in-situ testing device for the soil squeezing effect of precast pile groups includes several test unit components. The test unit components are in the shape of a rotating body, and the end faces of adjacent test unit components are flush to form a continuous side. The top of the test unit components is provided with several positioning parts arranged in a circular array around the rotation axis of the test unit components. The test unit components are detachably connected to a torque handle through the positioning parts. The test unit components have a hollow area inside, and several strain sensors are arranged in the hollow area. The strain sensors are electrically connected to a strain acquisition instrument.
[0008] This application comprises a testing device consisting of several test unit components. Each test unit component is individually tested using strain sensors installed in its internal hollowed-out areas. The deformation of the strain sensors reveals the compressive force acting on the test unit component. A torque handle allows rotation of the test unit components, and a positioning part facilitates the assembly and disassembly of each component. The testing device disclosed in this application can penetrate soil to conduct soil displacement effect tests according to different testing requirements. After testing, it can be disassembled and reused.
[0009] Preferably, the test unit component is a frustum shape with the cone angle pointing downwards. When the test device is pushed downwards into the soil, the sides of the frustum shape can be subjected to soil compressive force, which facilitates the detection by the strain sensor.
[0010] Preferably, the outer peripheral surfaces of several test unit components are combined to form a common frustum. This ensures that when the test device is inserted into the soil, the soil pressure exerted on the sides of the test device acts continuously and is detected by each test unit component, resulting in high continuity and accuracy of the testing structure.
[0011] Preferably, the torque handle is cross-shaped, with a protruding connecting part at the end of the torque handle, and the positioning part and the connecting part are inserted into each other. There are four connecting parts at the cross-shaped end of the torque handle. The four connecting parts cooperate with the four positioning parts to realize the synchronous action on four points on the end face of the test unit component, realize the reliable rotation of the test unit component, and facilitate the assembly and disassembly of each test unit component.
[0012] Preferably, the hollow area is a sealed cavity, and the strain sensor is fitted into one side of the cavity corresponding to the sidewall of the test unit component, with several strain sensors positioned in different directions. The sealed cavity protects the strain sensors, prevents soil from entering, and ensures the accuracy of the soil compression test results.
[0013] Preferably, adjacent test unit components are threadedly fixed together. This facilitates connection and disassembly.
[0014] Preferably, the lower side of the lowest test unit component is connected to an extrusion head, the lower end of which has a conical angle, and the upper end of the extrusion head is continuously connected to the lower side of the lowest test unit component. The conical angle on the extrusion head facilitates the extrusion of the testing device into the soil, making it easier to complete various tests.
[0015] Preferably, the extrusion head is conical in shape, with a cone angle larger than that of the test unit component. Several spiral guide grooves are provided on the sidewall of the extrusion head, arranged in a circumferential array around the axis of the extrusion head. The larger cone angle of the extrusion head reduces the likelihood of excessive wear, ensuring its reliability. Furthermore, due to the spiral guide grooves, when the test device is extruded into the soil, the grooves simultaneously displace the soil and exert a circumferential force on the extrusion head, causing it to spirally penetrate the soil. This improves the extrusion efficiency of the test device, prevents damage caused by unilateral stress on the extrusion head, and distributes the soil evenly around the circumference of the test device, thus improving test accuracy.
[0016] Beneficial effects: The precast pile group soil squeezing effect in-situ testing device can be used to complete the corresponding tests of soil squeezing test method and pile group soil squeezing effect test method, thereby improving the comprehensiveness of soil squeezing effect testing. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the structure of the in-situ testing device for the soil squeezing effect of precast pile groups disclosed in one embodiment of this utility model;
[0018] Figure 2 yes Figure 1 The schematic diagram of the test unit component in the embodiment shown;
[0019] Figure 3 yes Figure 2 Schematic diagram of the cross section at point II;
[0020] Figure 4 This is a schematic diagram of the structure of the precast pile group soil squeezing effect in-situ testing device combined with the testing unit components in one embodiment of the present invention.
[0021] Figure 5 This is a schematic diagram of the structure of an in-situ testing device for the soil squeezing effect of precast pile groups, disclosed in another embodiment of this utility model.
[0022] Figure 6 This is a schematic diagram of the torque handle in the in-situ testing device for the soil squeezing effect of precast pile groups disclosed in one embodiment of this utility model.
[0023] Figure 7 yes Figure 6 Side view;
[0024] Figure 8 and Figure 9 This is a schematic diagram of the precast pile group soil squeezing effect in-situ testing device relative to the soil mass during soil squeezing testing.
[0025] Figure 10 and Figure 11 This is a schematic diagram of the precast pile group soil squeezing effect in situ testing device relative to the soil when conducting pile group soil squeezing effect testing.
[0026] In the figure: Test unit component 1, first connecting stud 2, connecting screw hole 3, positioning part 4, hollow area 5, strain sensor 6, data acquisition line 7, strain acquisition instrument 8, extrusion head 9, spiral guide groove 10, soil 11, torque handle 12, connecting part 13, second connecting stud 14. Detailed Implementation
[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.
[0028] like Figures 1 to 11 As shown, an in-situ testing device for the soil squeezing effect of precast pile groups, proposed as one embodiment of this utility model, includes several test unit components 1. The test unit components 1 are in the shape of a rotating body. The end faces of adjacent test unit components 1 are flush to form a continuous side. The top of the test unit components 1 is provided with several positioning parts 4 arranged in a circular array around the rotation axis of the test unit components 1. The test unit components 1 are detachably connected to a torque handle 12 through the positioning parts 4. The test unit components 1 are provided with a hollow area 5 inside. Several strain sensors 6 are provided in the hollow area 5. The strain sensors 6 are electrically connected to a strain acquisition instrument 8.
[0029] This application discloses a testing device for testing the soil squeezing effect of precast pile groups. When the testing device is used, it is inserted under the soil mass 11. The continuous sides formed by adjacent test unit components 1 can all feel the pressure of the soil mass 11. The pressure of the soil mass 11 causes deformation on the sides of the test unit components 1, allowing the strain sensor 6 within the hollow area 5 to detect the squeezing force of the soil mass 11, thereby reliably achieving the testing of the soil squeezing effect. The torque handle 12 facilitates the assembly and disassembly of adjacent test unit components 1, improving the reliability of the combined application of the test unit components 1.
[0030] The phrase "the end faces of adjacent test unit components 1 are flush to form a continuous side surface" as stated in this utility model means that the relative end faces of adjacent test unit components 1 are flush and fit together, so that the side surfaces of adjacent test unit components 1 can be directly connected without the need for end face transition, thus hiding the end faces of test unit components 1. When the testing device is used, the end faces of test unit components 1 will not affect the accuracy of the soil squeezing test.
[0031] To protect strain sensor 6 and prevent interference with test unit component 1, for example, such as Figure 2 As shown, the hollow area 5 is a sealed cavity. The strain sensor 6 is fitted into the cavity on one side of the side wall corresponding to the test unit component 1, that is, the strain sensor 6 is located on the side wall of the test unit component 1. The strain sensors 6 are arranged in different directions. In this embodiment, there are four strain sensors 6, which are arranged in a circular array around the rotation axis of the test unit component 1 to provide reliable testing in all four directions of the test unit component 1. The test unit component 1 can be sealed to open and close the cavity. That is, the test unit component 1 has an opening on one side of the cavity, such as the side wall or end face of the test unit component 1, to complete the installation of the strain sensor 6. Then, the sealing is achieved by bonding, welding or screw connection to close the opening, thus closing the test unit component 1. Preferably, the sealing is placed on the end face of the test unit component 1.
[0032] Those skilled in the art will readily recognize that the number of test strain sensors 6 can be replaced with three, five, or other quantities. The strain sensors 6 are telecommunication connected to the strain acquisition instrument 8 via data acquisition line 7.
[0033] As a simple alternative to the above solution, the strain acquisition device 8 and the strain sensor 6 can be electrically connected via wireless transmission through a wireless transceiver or Bluetooth device.
[0034] In the above embodiment, adjacent test unit components 1 are threadedly fixed together. For example... Figure 2 As shown, the upper end of the test unit component 1 is provided with a connecting screw hole 3, and the lower end of the test unit component 1 is provided with a first connecting stud 2. The first connecting stud 2 protrudes outward to the outside of the test unit component 1 and is coaxially arranged with the test unit component 1. The first connecting stud 2 at the lower end of the upper test unit component 1 connects to the connecting screw hole 3 at the upper end of the adjacent test unit component 1 below it, realizing a reliable connection between adjacent test unit components 1. Since the test unit component 1 in this embodiment is shaped like a frustum with the cone angle pointing downwards, and the upper end surface of the test unit component 1 is larger than the lower end surface of the same test unit component 1, a positioning part 4 is provided on the upper end surface of the test unit component 1, and each test unit component 1 on the testing device is installed from bottom to top.
[0035] Furthermore, such as Figure 1 As shown, the outer peripheral surfaces of several test unit components 1 are combined to form a concentric frustum. An extrusion head 9 is connected to the lower side of the lowest test unit component 1. The lower end of the extrusion head 9 has a conical angle, and the upper end of the extrusion head 9 is continuously connected to the lower side of the lowest test unit component 1. The extrusion head 9 facilitates the insertion of the testing device into the soil 11.
[0036] Furthermore, such as Figure 4 As shown, to improve the strength of the extrusion head 9 and extend the life of the cone angle of the extrusion head 9, the extrusion head 9 is conical in shape, and the cone angle of the extrusion head 9 is larger than the cone angle of the test unit component 1. Several spiral guide grooves 10 are provided on the side wall of the extrusion head 9, and these spiral guide grooves 10 are arranged in a circumferential array around the axis of the extrusion head 9. The extrusion head 9 is rotatably connected to the test unit component 1. For example, a blind mounting hole is provided inside the extrusion head 9, and the first connecting stud 2 of the test unit component 1 extends into the blind mounting hole. A plane bearing is provided between the end face of the first connecting stud 2 and the blind mounting hole to transmit axial force, enabling the extrusion head 9 to rotate the loudness test unit component 1. The extrusion head 9 has a relatively large cone angle, which reduces the risk of excessive wear and ensures its reliability. Furthermore, due to the spiral guide groove 10, when the testing device extrudes the soil 11, the spiral guide groove 10 exerts a circumferential force on the extrusion head 9 while simultaneously dispersing the soil 11. This allows the extrusion head 9 to spirally extrude the soil 11, improving the extrusion efficiency of the testing device, preventing damage to the extrusion head 9 due to unilateral stress, and distributing the soil 11 evenly around the testing device, thus improving the accuracy of the test.
[0037] One embodiment of this utility model proposes an in-situ testing device for the soil displacement effect of precast pile groups. The torque handle 12 is cross-shaped, and its end has four protruding connecting portions 13, each corresponding to one of four positioning portions 4. The positioning portions 4 and connecting portions 13 are inserted into each other. Figure 2 and Figure 7 In the illustrated embodiment, the positioning part 4 is a blind hole structure, and the connecting part 13 is a protruding post structure. The connecting part 13 is inserted into the interior of the positioning part 4. The cross-section of the positioning part 4 can be circular, regular polygonal, etc., and the cross-sectional shape of the connecting part 13 can also be circular, regular polygonal, etc. A second connecting stud is provided at the upper center of the torque handle 12 to achieve threaded connection with an external torque device.
[0038] As a simple alternative to the above scheme, the positioning part 4 can be a protruding column structure and the connecting part 13 can be a socket structure.
[0039] The torque handle 12 is used to connect the test unit component 1 and drive the test unit component 1 to rotate around the axis of the test unit component 1, thereby realizing the soil compression test method of the adjacent test unit component 1 based on the above-mentioned precast pile group soil squeezing effect in-situ test device, which includes the following steps:
[0040] A. Select the number of test unit components 1 according to the depth and compression deformation of the test soil 11. Connect each test unit component 1 with bolts to form a continuously variable diameter columnar test pile. Number each test unit component 1 sequentially from bottom to top, such as... Figure 8and Figure 9 As shown;
[0041] B. The assembled columnar test pile is driven into the soil 11 by a pile driver. The strain readings of each test unit after penetration are recorded by a strain acquisition instrument wirelessly connected to the ground until the test pile is completely driven into the soil 11.
[0042] C. Based on the measured strain values, the soil compressive stress can be calculated using the calibrated conversion relationship:
[0043] P = k j ε;
[0044] In the formula: P is the converted soil compressive stress, ε is the measured strain value, and k is the stress. j The conversion factor is used to calibrate component 1 of the j-th test unit;
[0045] The soil displacement stiffness coefficient is calculated based on the difference in pressure after the component 1 of the test unit is pressed into different soil layers. For the i-th soil layer 11, its soil displacement stiffness coefficient can be calculated according to the following formula:
[0046]
[0047] In the formula: R m and R n These are the radii of the circles corresponding to the center positions of the m-th and n-th test unit component 1, respectively, as shown below. Figure 3 As shown in R, P m and P n The soil squeezing pressures measured when component 1 of the m-th and n-th test units is pressed into the i-th layer of soil are respectively, and the average value of the soil squeezing pressures calculated from the four directions is taken.
[0048] The i-th soil layer corresponds to a compression deformation of R. m -R n The soil squeezing stiffness coefficient at that time.
[0049] A method for testing the soil squeezing effect of a pile group based on the above-mentioned prefabricated pile group soil squeezing effect in situ testing device includes the following steps: S1, after the assembled test pile penetrates into the soil 11, record the initial strain value of each test unit component 1, and calculate the initial soil pressure value of the surrounding pile foundation before penetration.
[0050] After the S2 and #1 pile foundations were penetrated, the strain change values of component 1 in each test unit were recorded, such as... Figure 10 As shown, the soil pressure values at each measuring point after pile penetration are calculated, and the soil displacement pressure generated by pile penetration is obtained:
[0051]
[0052] In the formula: The soil displacement pressure measured in component 1 of the m-th test unit after the penetration of pile #1 is given. This represents the earth pressure value of component 1 in the m-th test unit after the penetration of pile #1. The earth pressure value of component 1 in the m-th test unit before the penetration of pile foundation #1;
[0053] S3, after the subsequent pile foundation is driven in, as Figure 11 As shown, the strain change values of each test unit component 1 are recorded respectively, and the soil pressure values of each measuring point after the pile foundation is penetrated are calculated. The soil squeezing pressure generated by the pile group penetration is further calculated.
[0054] S4. Based on the different strain values of strain sensors 6 in different directions of the same test unit component 1, analyze the differences in soil squeezing pressure in different directions.
[0055] S5. After the pile group soil squeezing effect test is completed, the test unit component 1 is dismantled one by one by the torque handle 12. The connecting part 13 of the torque handle 12 and the positioning part 4 on the test unit component 1 are connected and matched. The upper part of the torque handle 12 is connected to the drilling machine. The test unit is dismantled by the torque provided by the drilling machine. After the dismantling is completed, the remaining hole is backfilled.
Claims
1. A prefabricated group pile in-situ test device for soil squeezing effect, characterized in that, The application relates to a test unit component, which comprises a plurality of test unit components in the shape of a rotary body, the end faces of adjacent test unit components are flush to form a continuous side surface, the top of the test unit component is provided with a plurality of positioning portions arranged in a circumferential array around the rotary axis of the test unit component, the test unit component is detachably connected with a torsion handle through the positioning portions, the test unit component is internally provided with a hollow region, a plurality of strain sensors are arranged in the hollow region, and the strain sensors are electrically connected with a strain acquisition instrument.
2. The pre-bored pile group soil squeezing effect in-situ testing device according to claim 1, characterized in that, The test unit component is in the shape of a circular truncated cone with a downward taper angle.
3. The pre-bored pile group soil squeezing effect in-situ testing device according to claim 2, characterized in that, The outer circumferential surfaces of the plurality of test unit components are combined to be arranged as a common circular truncated surface.
4. The pre-bored pile group soil squeezing effect in-situ testing device according to claim 1, characterized in that, The torsion handle is in the shape of a cross, the end of the torsion handle is provided with a protruding connecting portion, and the positioning portion is insertedly matched with the connecting portion.
5. The pre-bored pile group soil squeezing effect in-situ testing device according to claim 1, characterized in that, The hollow region is a closed cavity, the strain sensors are arranged on one side of the side wall of the test unit component corresponding to the cavity, and the plurality of strain sensors are arranged in different directions.
6. The pre-bored pile soil squeezing effect in-situ testing device according to claim 1 or 2 or 3, characterized in that, The adjacent test unit components are fixedly connected through threads.
7. A pre-bored pile group soil squeezing effect in-situ testing device according to any one of claims 1 to 5, characterized in that, The lower side of the test unit component at the lowermost end is connected with a squeeze head, the lower end of the squeeze head is provided with a conical angle, and the upper end of the squeeze head is continuously arranged with the lower side of the test unit component at the lowermost end.
8. The pre-bored pile group soil squeezing effect in-situ testing device according to claim 7, characterized in that, The squeeze head is in the shape of a cone, the conical angle of the squeeze head is larger than the conical angle of the test unit component, a plurality of spiral guide grooves are arranged on the side wall of the squeeze head, and the plurality of spiral guide grooves are arranged in a circumferential array around the axis of the squeeze head.