A static pressure pile sinking experimental device and method with top defects

Abstract

The present invention relates to the technical field of building construction, and discloses a static pressure pile sinking test device and method for pile foundations with top grouting defects, comprising: a centrifuge, a data acquisition system, a pile foundation model, and a load applying device, wherein a model box for holding soil is provided inside the centrifuge, one end of the pile body extends into the model box and is covered by the soil, the top cover is connected to the pile body, and the top cover is also connected to the load applying device, and the load applying device drives the pile body to move in the model box through the top cover, and a hydraulic sensor and an earth pressure sensor are fixedly mounted on the top cover, and the hydraulic sensor and the earth pressure sensor are respectively connected to the data acquisition system signal. The present invention can not only accurately obtain the stress conditions of the pile foundation model during the static pressure settlement simulation process, but also provide data reference for operators, so that operators can adjust construction strategies in a timely manner.

Description

Technical Field

[0001] The invention relates to the technical field of building construction, in particular to a static pressure pile sinking test device and method with top defects. Background Art

[0002] Pile foundation is an important form of foundation, especially prefabricated piles, which are widely used in actual engineering due to their advantages such as easy production, fast pile formation, easy to control pile quality, high bearing capacity, and no influence from groundwater.

[0003] During the construction of the jacket pile foundation of a traditional offshore oil and gas platform, after the prefabricated pile section is penetrated into the seabed soil, the pile top is grouting and sealing is carried out. The grouting quality of the top grouting section must be ensured, otherwise the bearing capacity of the top cover area may not be fully utilized and the bearing capacity of the pile foundation may be affected.

[0004] Currently, there are few centrifuge test devices for statically driven piles. Experimental research on pore water pressure and soil pressure in hollow precast pipe pile foundations is primarily conducted in actual projects, often focusing on a single specific project scenario. Furthermore, in actual engineering applications, there is no effective strength conversion method for defects such as insufficient or uneven grouting in the top grouting area of ​​long piles. Instead, high safety factors are often used for estimation, resulting in inaccurate test data. Furthermore, it is difficult to measure the variation in excess pore water pressure in the soil during continuous pile penetration into the seabed soil. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that when a hollow prefabricated pipe pile is continuously penetrated into the soil, it is impossible to accurately and in real time obtain parameters such as the water pressure and soil pressure on the hollow prefabricated pipe pile.

[0006] In order to solve the above technical problems, the present invention provides a static pressure pile driving experimental device and method with top defects. By arranging a hydraulic sensor and an earth pressure sensor on the top cover, when the load application device drives the pile foundation model to continuously extend into the model box, the liquid pressure and soil pressure received by the pile foundation model are obtained in real time through the hydraulic sensor and the earth pressure sensor, and are read in real time through a data acquisition system, so that the operator can understand the stress condition of the pile foundation model in real time and accurately and adjust the construction strategy in time.

[0007] The present invention provides a static pressure pile driving experimental device with top defects, comprising: a centrifuge, a data acquisition system and a pile foundation model, wherein the device further comprises: a load applying device, wherein a model box for containing soil is provided inside the centrifuge, and the pile foundation model comprises: a pile body and a top cover, wherein one end of the pile body extends into the model box and is covered by the soil, and the top cover is detachably fixedly connected to the other end of the pile body, and the top cover is also connected to the load applying device, and the load applying device drives the pile body to move in the model box through the top cover, and a hydraulic pressure sensor and an earth pressure sensor are fixedly installed on the top cover, and the hydraulic pressure sensor and the earth pressure sensor are respectively connected to the data acquisition system for signal connection, and the top cover is also provided with a plurality of defect holes.

[0008] The above-mentioned static pressure pile driving experimental device with top defects, wherein the load applying device includes: a manipulator and a first driving device, the manipulator is fixedly connected to the first driving device, and the manipulator is also connected to the top cover, the first driving device can move in a first direction or a second direction, the first direction is parallel to the axis of the pile body, and the first direction is also perpendicular to the second direction.

[0009] The above-mentioned static pressure pile driving experimental device with top defects further includes: an axial force sensor, which is connected to the manipulator and is also connected to the data acquisition system signal.

[0010] In the above-mentioned static pressure pile driving experimental device with top defects, the manipulator is provided with a magnetic base, and the manipulator is connected to the top cover and the axial force sensor respectively through the magnetic base.

[0011] In the above-mentioned static pressure pile driving experimental device with top defects, the magnetic base includes an electromagnetic relay.

[0012] In the above-mentioned static pressure pile driving experimental device with top defects, a protective cover is fixedly provided on the manipulator, the top cover is at least partially located in the protective cover, and the axial force sensor is located in the protective cover.

[0013] The above-mentioned static pressure pile driving experimental device with top defects is provided with an extension section on the top cover to facilitate the gripping of the manipulator.

[0014] In the above-mentioned static pressure pile driving experimental device with top defects, a first sealing ring is further provided at the connection between the pile body and the top cover.

[0015] The static pressure pile sinking experimental device with top defects, wherein the defect hole is a cylindrical through hole, and the diameter of the defect hole is Wherein, Q is the flow rate of the soil body of the immersion liquid flowing through the top cover per unit time, v is the flow velocity of the soil body of the immersion liquid, and π is the pi constant.

[0016] The present invention also provides a method, which is applied to the above-mentioned static pressure pile driving experimental device with top defects, and includes the following steps:

[0017] Step S1: taking a soil mass of a preset weight W, pouring it into the model box, and consolidating it in the model box for a preset time D;

[0018] Step S2: fixing the pile body and the top cover together to form the pile foundation model, and fixing the hydraulic pressure sensor and the earth pressure sensor on the top cover;

[0019] Step S3: injecting the immersion liquid into the model box from bottom to top, and ensuring that the immersion liquid submerges the soil at a preset height H;

[0020] Step S4: starting the first driving device to move the first driving device toward the top cover and along the first direction by a preset distance L, then turning off the first driving device and opening the magnetic base, and sequentially fixing the axial force sensor and the top cover to the manipulator;

[0021] Step S5: connecting the hydraulic pressure sensor, the earth pressure sensor, and the axial force sensor to the data acquisition system respectively;

[0022] Step S6: turning on the first driving device again, causing the first driving device to drive the pile body to move at a constant speed along the first direction, and causing the end of the pile body away from the manipulator to extend into the model box, simulating a static pressure pile sinking process of the pile foundation model;

[0023] Step S7: The data acquisition system is obtained to display the data collected by the hydraulic sensor, the earth pressure sensor, and the axial force sensor in real time.

[0024] Compared with the prior art, the static pressure pile driving test device and method of the embodiment of the present invention with top defects have the following beneficial effects:

[0025] The present invention can not only accurately obtain the stress conditions of the pile foundation model during the static pressure settlement simulation process, but also provide data reference for operators, making it convenient for operators to adjust construction strategies in a timely manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is an overall schematic diagram of an embodiment of the present invention;

[0027] Figure 2 For the present invention Figure 1Schematic diagram of the medium load application device;

[0028] Figure 3 For the present invention Figure 1 Schematic diagram of the pile foundation model;

[0029] Figure 4 For the present invention Figure 3 Schematic diagram of a top view of the middle top cover.

[0030] In the figure, 1. centrifuge; 11. tool table; 2. data acquisition system; 21. slip ring; 22. data display terminal; 3. pile foundation model; 31. pile body; 32. top cover; 33. defect hole; 34. push rod; 35. extension section; 4. load applying device; 41. manipulator; 42. magnetic base; 5. model box; 61. hydraulic sensor; 62. soil pressure sensor; 63. axial force sensor; 71. protective cover; 72. first sealing ring; 8. fixed connector. DETAILED DESCRIPTION

[0031] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0032] In the description of the present invention, it should be understood that the terms "first direction" and "second direction" used in the present invention include but are not limited to the directions shown in the diagram. The "first direction" and "second direction" in the diagram are an embodiment shown to make this embodiment easier to understand, and it should not be considered that the "first direction" and "second direction" in the present invention are limited to the directions shown in the diagram.

[0033] like Figure 1As shown, the present invention provides a static pressure pile sinking experimental device with top defects, comprising: a centrifuge 1, a data acquisition system 2, a pile foundation model 3 and a load applying device 4. A model box 5 for containing soil is provided inside the centrifuge 1, and the pile foundation model 3 comprises: a pile body 31 and a top cover 32. One end of the pile body 31 extends into the model box 5 under the drive of the load applying device 4 and is covered by the soil to ensure that the pile body 31 can bear the pressure of the liquid and the soil. The top cover 32 is fixedly connected to the other end of the pile body 31 by a detachable connecting piece. The detachable connecting piece can be selected from bolts, snaps and other parts to facilitate the rapid assembly of the pile body 31 and the top cover 32 to form the pile foundation model 3. The top cover 32 is also fixedly connected to the load applying device 4. The load applying device 4 drives the pile body 31 to move in the model box 5 through the top cover 32. The top cover 32 is provided with a hydraulic pressure sensor 61 and an earth pressure sensor 62, which are respectively connected to the data acquisition system signal 2. The hydraulic pressure sensor 61 and the earth pressure sensor 62 detect the liquid pressure and the earth pressure of the pile foundation model 3 in real time. The construction personnel can understand the pressure parameters of the pile body 31 during the continuous static pressure settlement process, which is convenient for the construction personnel to adjust the strategy of the pile foundation model 3 during the continuous static pressure settlement in time. A number of defect holes 33 are also provided on the top cover 32, and each defect hole 33 is used to simulate the defects generated by the pile foundation model 3 during filling in the actual project, so that the whole simulation process is closer to the actual project situation and the accuracy of the pressure parameters measured during the simulation process is increased.

[0034] Preferably, the centrifuge 1 is a drum centrifuge, and the overall shape of the pile body 31 of the pile foundation model 3 is a hollow cylinder, which is similar to the shape of the pile foundation in the actual project. The length, inner diameter and outer diameter of the pile body 31 can be proportionally reduced according to the above parameters of the pile foundation in the actual project. The material of the pile foundation model 3 needs to be consistent with the material of the pile foundation in the actual project to increase the accuracy of the entire simulation process.

[0035] Further, as a preferred embodiment, Figure 1 As shown, the overall shape of the model box 5 is a hollow rectangular parallelepiped, and a plurality of through holes (not shown in the figure) are arranged at equal intervals along the height direction on the side of the model box 5 facing the load applying device 4. Each through hole is used for one end of the pile body 31 to extend into the model box 5, and the inner diameter of each through hole matches the outer diameter of the pile body 31 to avoid water seepage, soil seepage, etc. of the pile foundation model 3 during the test; in order to increase the sealing performance of the pile foundation model 3 and the model box 5, a second sealing ring can also be provided in each through hole of the model box 5 to enhance the anti-seepage ability of the model box 5.

[0036] Furthermore, as a preferred embodiment, a mud adding pipe (not shown in the figure) is also provided at the bottom of the model box 5. The soil is first penetrated into the model box 5 through the mud adding pipe. After the soil is solidified in the model box 5 for a period of time, the soaking liquid is injected into the model box 5 through the mud adding pipe.

[0037] Further, as a preferred embodiment, Figure 1 and Figure 2 As shown, the load applying device 4 includes: a manipulator 41 and a first driving device (not shown in the figure), the manipulator 41 is fixedly connected to the first driving device, and the manipulator 41 is also connected to the top cover 32, and the first driving device can move in a first direction or a second direction, the first direction is parallel to the axis of the pile body 31, and the first direction is also perpendicular to the second direction.

[0038] Further, as a preferred embodiment, Figure 2 As shown, the first driving device can be in the form of a slide rail assembly and a power base. The slide rail assembly includes: a first slide rail and a second slide rail. The length direction of the first slide rail is parallel to the axis of the pile body 31, and the length direction of the second slide rail is parallel to the height direction of the model box 5. The first slide rail is slidably set on the first slide rail, and the power base is slidably set on the first slide rail. The manipulator 41 is fixed on the power base through a fixed connecting piece. The power base can drive the manipulator 41 to slide along the length direction of the first slide rail, that is, the first direction. The first slide rail can drive the power base and the manipulator 41 to slide along the length direction of the second slide rail, that is, the second direction at the same time.

[0039] Further, as a preferred embodiment, Figure 2 As shown, the above-mentioned static pressure pile driving experimental device with top defects also includes: an axial force sensor 63, the axial force sensor 63 is connected to the manipulator 41, and the axial force sensor 63 is also connected to the data acquisition system 2 signal. The axial force sensor 63 is used to measure the axial force applied by the manipulator 41 to the top cover 32 of the pile foundation model 3, so as to prevent the manipulator 41 from applying excessive force to the top cover 32, causing the top cover 32 to be damaged by excessive force.

[0040] Further, as a preferred embodiment, Figure 2 As shown, a magnetic base 42 is provided on the manipulator 41. The magnetic base 42 is fixed on the power base through a fixed connector 8. The fixed connector 8 can be made of bolts, snaps and other parts. The magnetic base 42 is used to generate a magnetic channel inside the manipulator 41, so that the top cover 32 and the axial force sensor 63 are fixed on the manipulator 41 by magnetism.

[0041] Preferably, the magnetic base 42 includes an electromagnetic relay, which can realize the quick installation of the top cover 32 and the axial force sensor 63 by powering on or off the magnetic base. In addition, the electromagnetic relay can generate a large magnetic force, which can stably install the top cover 32 and the axial force sensor 63 on the manipulator 41.

[0042] Further, as a preferred embodiment, Figure 2 As shown, a protective cover 71 is fixedly provided on the manipulator 41 through a fixed connecting piece 8, and a push rod 34 is also provided on the top cover 32. The interior of the protective cover 71 has a raised space, and one end of the push rod of the top cover 32 extends into the raised space of the protective cover 71. The axial force sensor 63 is entirely located in the raised space of the protective cover 71. The top cover 32 and the axial force sensor 63 can be pre-installed in the protective cover 71 through the protective cover 71, so as to avoid the top cover 32 and the axial force sensor 63 from falling off when being installed on the manipulator 41, thereby improving the installation efficiency and accuracy.

[0043] Further, as a preferred embodiment, Figure 3 As shown, an extension section 35 is provided on the top cover 32 to facilitate the mechanical arm of the manipulator 41 to grasp the top cover 32 .

[0044] Further, as a preferred embodiment, Figure 3 As shown, a first sealing ring 72 is further provided at the connection between the pile body 31 and the top cover 32 to prevent liquid seepage, thereby preventing liquid and / or soil from penetrating into the connection between the pile body 31 and the top cover 32, thereby ensuring the firmness of the pile foundation model 3 after the pile body 31 and the top cover 32 are assembled.

[0045] Further, as a preferred embodiment, Figure 1 As shown, the data acquisition system 2 includes a data processing module (not shown in the figure), a data display terminal 22 and a slip ring 21. The data processing module and the data display terminal 22 are both fixedly arranged on the tool table 11 of the centrifuge 1. The data processing module is respectively connected to the hydraulic sensor 61, the earth pressure sensor 62 and the axial force sensor 63 for signal connection. The data processing module is also connected to the data display terminal 22 through the slip ring 21. The data processing module obtains the liquid pressure, soil pressure and axial force data of the pile foundation model 3 collected by the hydraulic sensor 61, the earth pressure sensor 62 and the axial force sensor 63, and transmits them to the data display terminal 22 for display through the slip ring 21, so that the operator can understand the force parameters of the pile foundation model 3 in real time and change the static pressure settlement strategy of the pile foundation model 3 based on the above parameters.

[0046] Furthermore, as a preferred embodiment, the data processing module is respectively connected to the hydraulic sensor 61, the earth pressure sensor 62 and the axial force sensor 63 by signals, and can be connected by wires such as data cables or by wireless connections such as Bluetooth.

[0047] Preferably, the data display terminal 22 can be a display device such as a computer or a display instrument.

[0048] Further, as a preferred embodiment, Figure 3 As shown, the defect hole 33 is a cylindrical through hole, and the diameter of the defect hole 33 is Wherein, Q is the flow rate of the soil immersed in the liquid flowing through the top cover 32 per unit time, v is the flow velocity of the soil immersed in the liquid, and π is the pi constant.

[0049] The top cover 32 simulates the grouting section at the top of the pile foundation in actual engineering. The concrete seepage characteristics are equivalent to a cylindrical defect hole with a certain diameter that runs through the entire concrete pouring layer. The diameter conversion method of the defect hole 33 is as follows:

[0050] 1) Assuming that the pressure difference between the upper and lower layers of the pile foundation concrete pouring layer is P0, which is equivalent to a water head of height H0, and assuming that the thickness of the concrete soil pouring layer is L, then the water head gradient generated by the pressure difference P0 is

[0051] 2) The cross-sectional area of ​​a pile foundation with a diameter of D is

[0052] 3) Under the pressure difference of P0, the flow rate through the top cover 32 per unit time is Q=kiA, where k is the permeability coefficient of the top cover 32 in the concrete grouting section;

[0053] 4) According to the fluid mechanics formula To generate a flow with a given velocity v, the seepage characteristics of the top cover 32 at the concrete grouting end can be equivalent to a flow through the entire concrete pouring layer, thereby obtaining a diameter of The inner diameter of the circular threaded opening through hole, that is, the defect hole 33;

[0054] 5) In engineering prejudgment, the opening diameter may be appropriately magnified for conservative purposes. This magnification is considered to facilitate the study of changes in pile foundation bearing capacity under extreme conditions, such as large continuous cracks in concrete. Furthermore, if the opening area is too small, the minimum diameter that facilitates machining should be used when constructing the actual top cover 32 model.

[0055] The present invention also provides a method, which is applied to the above-mentioned static pressure pile driving experimental device with top defects, comprising the following steps:

[0056] Step S1: taking a soil mass of a preset weight W, pouring it into the model box 5, and consolidating it in the model box 5 for a preset time D;

[0057] Preferably, the preset weight W of the soil can be adapted according to the size of the internal space of the model box 5. Generally, the volume of the model box 5 occupied by the soil does not exceed three-quarters of the total volume of the model box. The preset soil consolidation time D is 3 to 5 days.

[0058] Step S2: The pile body 31 and the top cover 32 are fixedly mounted together to form the pile foundation model 3, and the hydraulic pressure sensor 61 and the earth pressure sensor 62 are fixedly mounted on the top cover 32;

[0059] Step S3: injecting the immersion liquid into the model box 5 from bottom to top, and ensuring that the immersion liquid is above the preset height H of the soil;

[0060] Preferably, the preset height H of the immersion liquid above the soil is 3 to 5 cm;

[0061] Step S4: Start the first driving device and move it toward the top cover 32 along the first direction for a preset distance L. Then, turn off the first driving device and open the magnetic base 42 to sequentially fix the axial force sensor 63 and the top cover 32 on the manipulator 41.

[0062] Step S5: Connect the hydraulic pressure sensor 61, the earth pressure sensor 62, and the axial force sensor 63 to the data acquisition system 2 respectively;

[0063] Step S6: turning on the first driving device again, causing the first driving device to drive the pile body 31 to move at a constant speed along the first direction, and causing the end of the pile body 31 away from the manipulator 41 to extend into the model box 5, simulating the static pressure pile sinking process of the pile foundation model 3;

[0064] Step S7: The data acquisition system 2 displays the data collected by the hydraulic pressure sensor 61, the earth pressure sensor 62, and the axial force sensor 63 in real time.

[0065] Furthermore, as a preferred embodiment, the above-mentioned liquid pressure can be the pressure of seawater on the pile foundation model 3 during seabed construction, or the pressure of freshwater on the pile foundation model 3 during construction at the bottom of rivers, lakes, etc. Similarly, the above-mentioned soil pressure can be the pressure of seabed soil on the pile foundation model 3 during seabed construction, or the pressure of soil during construction at the bottom of rivers, lakes, etc. In the specific simulation of static pressure settlement, the soil and liquid in the model box 5 can be selected according to the actual construction environment. For example, when constructing on the seabed, the soil and seawater on the seabed can be selected for proportioning. When constructing at the bottom of rivers, lakes, etc., the soil and fresh water at the bottom of rivers, lakes, etc. can be selected for proportioning. Selecting appropriate soil and liquid according to different construction environments can maximize the control of variables that may affect the experimental results, thereby facilitating the acquisition of more accurate experimental results.

[0066] The working process of the present invention is as follows: by assembling the top cover 32 and the pile body 31 into a pile foundation model 3, the pile foundation model 3 is extended into the model box 5 under the drive of the load applying device 4, and can simulate the static pressure settlement process in the model box 5. During this process, the hydraulic sensor 61, the soil pressure sensor 62 and the axial force sensor 63 obtain the liquid pressure, soil pressure and axial force exerted on the pile foundation model 3 in real time, and transmit them to the data acquisition system 2, which records and displays them. This not only can accurately obtain the force conditions of the pile foundation model 3 during the simulated static pressure settlement process, but also provide data reference for the operator, so that the operator can adjust the construction strategy in time.

[0067] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary counting personnel in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as within the scope of protection of the present invention.

Claims

1. A static pressure pile driving test device with top defects, comprising: A centrifuge, a data acquisition system, and a pile foundation model, characterized in that they further include: a load applying device, a model box for containing soil is provided inside the centrifuge, the pile foundation model includes: a pile body and a top cover, one end of the pile body extends into the model box and is covered by the soil, the top cover is detachably fixedly connected to the other end of the pile body, the top cover is also connected to the load applying device, the load applying device drives the pile body to move in the model box through the top cover, a hydraulic sensor and an earth pressure sensor are also fixedly installed on the top cover, the hydraulic sensor and the earth pressure sensor are respectively connected to the data acquisition system signals, and the top cover is also provided with a plurality of defect holes; The load applying device includes: a manipulator and a first driving device, wherein the manipulator is fixedly connected to the first driving device and is also connected to the top cover, and the first driving device can move in a first direction or a second direction, wherein the first direction is parallel to the axis of the pile body and is also perpendicular to the second direction; The static pressure pile driving experimental device with top defects further includes: an axial force sensor, the axial force sensor is connected to the manipulator, and the axial force sensor is also connected to the data acquisition system signal; the axial force sensor is arranged at one end of the manipulator close to the top cover; The manipulator is provided with a magnetic base, and the manipulator is connected to the top cover and the axial force sensor respectively through the magnetic base.

2. The static pressure pile driving test device with top defects according to claim 1 is characterized in that: The magnetic base includes an electromagnetic relay.

3. The static pressure pile driving test device with top defects according to claim 1 is characterized in that: A protective cover is fixedly provided on the manipulator, the top cover is at least partially located in the protective cover, and the axial force sensor is located in the protective cover.

4. The static pressure pile driving test device with top defects according to claim 3 is characterized in that: The top cover is provided with an extension section which is convenient for the robot to grasp.

5. The static pressure pile driving test device with top defects according to any one of claims 1 to 4, characterized in that: A first sealing ring is also provided at the connection between the pile body and the top cover.

6. The static pressure pile driving test device with top defects according to claim 5 is characterized in that: The defect hole is a cylindrical through hole, and the diameter of the defect hole is Wherein, Q is the flow rate of the soil body of the immersion liquid flowing through the top cover per unit time, v is the flow velocity of the soil body of the immersion liquid, and π is the pi constant.

7. A method, applied to the static pressure pile driving test device with top defects as claimed in claim 6, characterized in that: The steps include: Step S1: taking a soil mass of a preset weight W, pouring it into the model box, and consolidating it in the model box for a preset time D; Step S2: fixing the pile body and the top cover together to form the pile foundation model, and fixing the hydraulic pressure sensor and the earth pressure sensor on the top cover; Step S3: injecting the immersion liquid into the model box from bottom to top, and ensuring that the immersion liquid submerges the soil at a preset height H; Step S4: starting the first driving device to move the first driving device toward the top cover and along the first direction by a preset distance L, then turning off the first driving device and opening the magnetic base, and sequentially fixing the axial force sensor and the top cover to the manipulator; Step S5: connecting the hydraulic pressure sensor, the earth pressure sensor, and the axial force sensor to the data acquisition system respectively; Step S6: turning on the first driving device again, causing the first driving device to drive the pile body to move at a constant speed along the first direction, and causing the end of the pile body away from the manipulator to extend into the model box, simulating a static pressure pile sinking process of the pile foundation model; Step S7: The data acquisition system is obtained to display the data collected by the hydraulic sensor, the earth pressure sensor, and the axial force sensor in real time.

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