Device and method for testing in-situ pore pressure of deep hole of deep foundation

Abstract

The invention discloses a deep foundation deep hole in-situ hole pressure testing device and method. The device comprises a long connecting pipe formed by sequential threaded connection of a plurality of extension pipes, and an in-situ pore pressure monitoring pipe is in threaded connection with the head of the long connecting pipe. The method comprises an assembling and monitoring method of the deep foundation deep hole in-situ hole pressure testing device and a foundation horizontal consolidation coefficient obtaining method based on the deep foundation deep hole in-situ hole pressure testing device. According to the device and the method, the pore pressure time-history curve of the deep covering layer can be accurately and rapidly measured, the device has good working performance in the underground ultra-deep environment, the horizontal consolidation coefficient is obtained through a reasonable data analysis method according to in-situ pore pressure data, the result is clear in physical significance and high in accuracy, and the device and the method have good application prospects. The problems that conventional pore pressure measuring equipment works normally for a long time in the ultra-deep environment and parameters such as the horizontal consolidation coefficient of a foundation are accurately obtained are solved.

Description

Technical Field

[0001] The invention belongs to the field of in-situ pore pressure measurement of deep foundations, and particularly relates to an in-situ pore pressure testing device and method for deep foundation deep holes. Background Art

[0002] During deep foundation construction, accurately monitoring the dynamic changes in pore water pressure is crucial for assessing foundation stability and long-term safety. Currently, there are two main methods for measuring pore water pressure: one is to bury a piezometer directly at the designed depth. While this does not affect surface vibration operations, the sensor is easily damaged and struggles to maintain stable operation over the long term. The other is to use a pore water penetration device. However, during vibration liquefaction tests, the vibration of the probe rod and protective shell can affect test accuracy.

[0003] To measure the pore pressure changes generated during construction, buried borehole meters are generally used for measurement. The particle content and particle size of the mud water in the hole affect the measurement accuracy, but there is a lack of standardized hole cleaning methods and filter layer protection standards; there are no unified requirements for the type and construction method of directional backfill soil after installation.

[0004] Construction in deep strata is complex, generating significant pore water stresses in the soil due to static plastic deformation and dynamic forces. However, existing monitoring and analysis methods remain unclear about the mechanisms and impacts of pore water pressure generation, leading to inaccurate measurements of soil parameters such as the consolidation coefficient. Summary of the Invention

[0005] In order to solve the problems existing in the background technology, the present invention provides an in-situ pore pressure testing device and method for deep foundation deep holes, which solves the technical problems that the existing technology lacks standardized hole cleaning methods and filter layer protection standards; lacks unified requirements for the types and construction methods of directional backfill soil after installation; and lacks a method for accurately measuring the consolidation coefficient.

[0006] The technical solutions adopted in the present invention include:

[0007] 1. An in-situ pore pressure testing device for deep holes in deep foundations:

[0008] It includes several extension tubes and in-situ pore pressure monitoring tubes; multiple extension tubes are threadedly connected in sequence to form a long connecting tube, and the in-situ pore pressure monitoring tube is threadedly connected to the head of the long connecting tube; each of the extension tubes is a hollow steel tube, and the two ends of the hollow steel tube are respectively a closed end with an external thread and an open end with an internal thread; the open ends and closed ends of multiple extension tubes are threadedly connected in sequence to form a long connecting tube; each of the in-situ pore pressure monitoring tubes includes a hollow monitoring steel tube and a pore pressure sensor; the two ends of the monitoring steel tube are respectively a sealed end with an external thread and an open end with an internal thread, and the open end of the in-situ pore pressure monitoring tube is threadedly connected to the closed end of the extension tube at one end of the long connecting tube; the pore pressure sensor is arranged in the middle of the monitoring steel tube, and quartz sand is filled between the pore pressure sensor and the inner wall of the monitoring steel tube.

[0009] The in-situ borehole pressure monitoring tube also includes gauze and a supporting hole plug pad; a plurality of flower holes and a wiring hole are opened on the outer circumference of the monitoring steel pipe, and a supporting hole plug pad is installed on the wiring hole. The signal line of the borehole pressure sensor is led out to the outside of the in-situ borehole pressure monitoring tube through the supporting hole plug pad; a layer of gauze is wrapped around the outer circumference of the monitoring steel pipe wrapped with gauze to form a filter layer, and the led-out signal line is wrapped around the outer circumference of the monitoring steel pipe wrapped with gauze and the outer circumference of the long connecting pipe and is finally electrically connected to the collector along a spiral ascending wiring method.

[0010] 2. Assembly and monitoring method of a deep foundation deep hole in-situ pore pressure testing device:

[0011] S1. Drill a hole in the monitoring area. After drilling is completed, pour clean water into the hole until clean water returns to the hole and then stop pouring.

[0012] S2. Determine the number of extension tubes according to the required monitoring depth, and thread the open ends and closed ends of multiple extension tubes together in sequence to form a long connecting tube.

[0013] S3. After saturating the pore pressure sensor, assemble the deep foundation deep hole in-situ pore pressure testing device.

[0014] S4. Arrange the assembled deep foundation deep hole in-situ pore pressure testing device at a preset position and perform monitoring to obtain a pore pressure time history curve at the monitoring position.

[0015] The step S3 is specifically as follows:

[0016] S31. Remove the filter on the pore pressure sensor head, and soak the filter and the pore pressure sensor without the filter in clean water for several hours to saturate them.

[0017] S32. Install the saturated filter on the head of the pore pressure sensor, and place the saturated pore pressure sensor with the filter in the middle of the monitoring steel pipe, and lead the data line through the supporting hole plug pad.

[0018] S33. Add quartz sand to the monitoring steel pipe until it is full, and wrap gauze around the outer periphery of the monitoring steel pipe to form an anti-filter layer. The data line of the pore pressure sensor is spirally wrapped around the gauze surface of the outer periphery of the monitoring steel pipe. The data line is protected and fixed with cable ties and tape to obtain an in-situ pore pressure monitoring pipe.

[0019] S34. Connect the in-situ pore pressure monitoring tube to the head of the long connecting tube, and spirally wind the data line of the pore pressure sensor around the outer circumference of the long connecting tube, and finally electrically connect it to the collector to obtain an assembled deep foundation deep hole in-situ pore pressure testing device.

[0020] The step S4 is specifically as follows:

[0021] S41. Lower the deep foundation deep hole in-situ pore pressure testing device to a designated location.

[0022] S42. Calculate the volume difference between the monitoring hole and the volume of the deep foundation deep hole in situ pore pressure testing device, and backfill the area between the deep foundation deep hole in situ pore pressure testing device and the monitoring hole with a volume corresponding to the volume difference after the device is lowered to the designated position.

[0023] S43. After backfilling is completed, the deep foundation deep hole in-situ pore pressure testing device performs real-time monitoring to obtain a pore pressure time history curve at the monitoring position.

[0024] 3. A method for obtaining the horizontal consolidation coefficient of a deep foundation deep hole in-situ pore pressure testing device:

[0025] D1. Use numerical simulation analysis software to construct a formation numerical model to obtain a completed formation numerical model; obtain a number of influencing factors, and input all the influencing factors into the completed formation numerical model to obtain a formation numerical model that includes all the influencing factors.

[0026] D2. Use the deep foundation deep hole in-situ pore pressure testing device to monitor the position to be tested, obtain the pore pressure time history curve of the position to be tested, and obtain an interference-free pore pressure time history curve based on the formation numerical model containing all influencing factors and the pore pressure time history curve of the position to be tested.

[0027] D3. Obtain the horizontal consolidation coefficient of the foundation based on the undisturbed pore pressure time history curve.

[0028] The step D1 is specifically as follows:

[0029] D11. Grid the monitoring site and construct a stratum numerical model using finite difference grids in the numerical simulation analysis software. Set the size of the monitoring site, grid size, and constitutive model in the stratum numerical model, as well as the boundary conditions and initial conditions of the stratum numerical model.

[0030] D12. Obtain the preliminary construction geological survey data to determine the soil parameters of the ground stratum distribution, density, Poisson's ratio and permeability coefficient, and input the soil parameters into the stratum numerical model to obtain the completed stratum numerical model.

[0031] D13. Determine multiple factors affecting pore pressure changes during construction based on field data and construction methods, and input all influencing factors into the formation numerical model to obtain a formation numerical model that includes all influencing factors.

[0032] The step D2 is specifically as follows:

[0033] D21. Conduct pore pressure test simulation experiments for each influencing factor in the formation numerical model containing all influencing factors, and obtain the pore pressure time history curve of a single influencing factor corresponding to each influencing factor.

[0034] D22. Assemble the deep foundation deep hole in-situ pore pressure testing device and place it at a preset position to monitor and obtain a pore pressure time history curve at the position to be tested.

[0035] D23. Subtract the pore pressure time history curves of all individual influencing factors from the pore pressure time history curve measured at the position to be measured, and finally obtain the pore pressure time history curve without interference.

[0036] The influencing factors include seepage, high-pressure water ejected from the machine, hole expansion, extrusion and vibration energy input.

[0037] The horizontal consolidation coefficient of the foundation is obtained by the following formula of the pore pressure time history curve without interference:

[0038]

[0039] Where u is the pore pressure, t is the dissipation time, C h is the horizontal consolidation coefficient of the foundation, and r is the radial distance between the construction center and the pore pressure sensor.

[0040] The beneficial effects of the present invention are:

[0041] 1. The assembly and monitoring method of the present invention can be carried out without disturbing the surrounding soil, and is simple to operate. The test results are highly reliable and accurate, providing a basis for further in-situ characteristic parameter testing of deep soil foundations.

[0042] 2. The device of the present invention places the pore pressure sensor into the monitoring steel pipe and wraps it with gauze for reverse filtration, so that the sand filled in the monitoring steel pipe will not be lost, and the pore pressure sensor will not be shifted or pierced, thereby ensuring the data accuracy of the pore pressure sensor during long-term service.

[0043] 3. The depth to which the pore pressure sensor is placed in the device of the present invention is controlled by the extension tube connected to it. The number and length of the extension tube can be continuously and freely adjusted. The vertical lowering method of the device can better control the posture of the pore pressure sensor and the overall structure of the in-situ pore pressure monitoring tube. Therefore, the pore pressure sensor can be accurately and conveniently adjusted and controlled to be lowered to a preset depth.

[0044] 4. The present invention adopts a layered backfill method to solve the problem of backfilling the gap between the soil around the in-situ pore pressure monitoring tube and the in-situ pore pressure monitoring tube, improves the accuracy of pore pressure measurement, and avoids the problem of internal and external cross-holes.

[0045] 5. The method for obtaining the horizontal consolidation coefficient of the foundation of the present invention includes separating the influencing factors of the pore pressure source by numerical simulation and static and dynamic analysis coupling, and obtaining the horizontal consolidation coefficient of the foundation by fitting the in-situ pore pressure time history curve. The result has clear physical meaning and high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 Schematic diagram of the structure of the in-situ pore pressure monitoring tube.

[0047] Figure 2 Schematic diagram of the structure of the pore pressure sensor.

[0048] Among them, it includes an in-situ pore pressure monitoring pipe 1, a supporting pore plug pad 2, a pore pressure sensor 3, a filter 31, and a sensor body 32. DETAILED DESCRIPTION

[0049] The present invention is described in more detail below with reference to the accompanying drawings and examples. However, the present invention is not limited thereto. A person skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications are considered to be within the scope of protection of the present invention. Any matters not described in detail in this specification constitute prior art known to those skilled in the art.

[0050] like Figure 1 As shown, the deep foundation deep hole in-situ pore pressure testing device of this embodiment:

[0051] The invention comprises a plurality of extension tubes and an in-situ borehole pressure monitoring tube 1; the plurality of extension tubes are threadedly connected in sequence to form a long connecting tube to extend the length, and the in-situ borehole pressure monitoring tube 1 is threadedly connected to the head of the long connecting tube. Each extension tube is a hollow galvanized steel tube, and the two ends of the hollow galvanized steel tube are respectively a closed end with external threads and an open end with internal threads; the open ends and closed ends of the plurality of extension tubes are threadedly connected in sequence to form a long connecting tube to extend the length; each in-situ borehole pressure monitoring tube 1 comprises a hollow monitoring steel tube and a borehole pressure sensor 3; the two ends of the monitoring steel tube are respectively a sealed end with external threads and an open end with internal threads, and the open end of the in-situ borehole pressure monitoring tube 1 is threadedly connected to the closed end of the extension tube at one end of the long connecting tube; the borehole pressure sensor 3 is arranged in the middle of the monitoring steel tube, and the space between the borehole pressure sensor 3 and the inner wall of the monitoring steel tube is filled with quartz sand to ensure that the borehole pressure sensor 3 is always located in the middle of the monitoring steel tube.

[0052] The in-situ borehole pressure monitoring pipe 1 also includes gauze and a supporting hole plug pad 2; a plurality of flower holes and a wiring hole are opened on the outer circumference of the monitoring steel pipe, and the supporting hole plug pad 2 is installed on the wiring hole. The signal line of the borehole pressure sensor 3 is led out to the outside of the in-situ borehole pressure monitoring pipe 1 through the supporting hole plug pad 2; a layer of gauze is wrapped around the outer circumference of the monitoring steel pipe to form an anti-filter layer to prevent the internal quartz sand from flowing out and causing the fixed position of the sensor to change. The led-out signal line is wrapped around the outer circumference of the monitoring steel pipe wrapped with gauze and the outer circumference of the long connecting pipe and is finally electrically connected to the collector in a spiral ascending wiring manner. Figure 2 As shown, the pore pressure sensor 3 is composed of a filter 31 at the head and a sensor body 32 .

[0053] In this embodiment, the support hole plug pad 2 is designed as a circular anti-static rubber protective pad, which is placed in the wiring hole of the monitoring steel pipe. The data line of the pore pressure sensor 3 passes through it to provide buffer protection at the easily bent parts. It is used to wrap and reinforce the opening when the data line is routed outside the hole. This prevents the pore pressure sensor 3 from being scratched by the outer sleeve at the corner when the cable is pulled out during the lowering of the pore pressure sensor 3 and when the in-situ pore pressure test device in deep foundation deep holes is pulled out, thus providing shear protection. The pore pressure sensor 3 adopts the BGK-4500S vibrating wire pore pressure sensor, which can be used for pressure monitoring such as seepage pressure, pore water pressure, uplift pressure, and pipeline pressure. The extension tube has no holes and is available in various lengths such as 1m and 2m. Its main purpose is to be connected to the in-situ pore pressure monitoring pipe 1 equipped with the pore pressure sensor 3 through a threaded connection so that the pore pressure sensor 3 can be lowered to a specified depth. The data collector used is model BGK-G2-DVW-8 / 16. The data collector is connected to the G cloud platform (BGKLogger software) and transmits data to the G cloud platform for processing. The integrated monitoring station composed of the data collector, pore pressure sensor 3 and G cloud platform can complete the automatic measurement, data processing, chart production, abnormal measurement value alarm and other tasks of various engineering safety monitoring instruments.

[0054] The assembly and monitoring method of this embodiment is implemented according to the following steps:

[0055] S1. Drill a hole in the monitoring area. After drilling, pour clean water into the hole until clean water returns to the hole. This ensures that after the pore pressure sensor 3 is installed, the permeable stone on the head of the pore pressure sensor 3 will not be blocked by soil particles, thereby affecting the measurement accuracy. The pouring time should be 30-45 minutes.

[0056] S2. Determine the number of extension pipes and thus the length of the long connecting pipe according to the actual conditions of the foundation soil and the required monitoring depth; and thread the open ends and closed ends of the multiple extension pipes in sequence to form a long connecting pipe.

[0057] S3, saturate the pore pressure sensor 3 and assemble an in-situ pore pressure test device for a deep hole in a deep foundation.

[0058] S31. Remove the filter 31 on the head of the pore pressure sensor 3, and soak the filter 31 and the pore pressure sensor 3 without the filter 31 in clean water for several hours to saturate them. In a specific implementation, they are generally soaked in clean water for 24 hours.

[0059] S32. Install the saturated filter 31 on the head of the pore pressure sensor 3 without the filter 31, and place the saturated pore pressure sensor 3 with the filter 31 in the middle of the monitoring steel pipe, and lead the data line through the supporting hole plug pad 2.

[0060] In specific implementation, the front end cavity of the pore pressure sensor 3 must be vented before installation to avoid measurement errors during operation. A simple venting method is to gently pull out the front end filter 31 along the axial direction of the sensor body 32, and then immerse the sensor body 32 and the filter 31 in a container filled with clean water, and then slowly push the filter 31 into the sensor body 32 in the water to saturate the water in the front end cavity of the pore pressure sensor 3.

[0061] S33. Add quartz sand to the monitoring steel pipe until it is full, and wrap gauze around the outer periphery of the monitoring steel pipe to form an inverse filter layer. Wrap the data line of the pore pressure sensor 3 in a spiral shape on the gauze surface of the outer periphery of the monitoring steel pipe. Use cable ties and tape to protect and fix the data line. At the same time, apply appropriate amount of vaseline on the surface of the monitoring steel pipe for lubrication to obtain the in-situ pore pressure monitoring pipe 1.

[0062] In a specific implementation, when pouring quartz sand, the quartz sand is poured slowly and densely from the upper part of the monitoring steel pipe to ensure that the pore pressure sensor 3 is placed vertically without deviation.

[0063] S34. Connect the in-situ pore pressure monitoring tube 1 to the head of the long connecting tube, and spirally wind the data line of the pore pressure sensor 3 around the outer circumference of the long connecting tube, and finally electrically connect it to the collector to obtain an assembled deep foundation deep hole in-situ pore pressure testing device.

[0064] Connecting the in-situ pore pressure monitoring tube 1 to the head of the long connecting tube specifically involves threading the unsealed internal thread end of the in-situ pore pressure monitoring tube 1 to the sealed external thread end of the long connecting tube.

[0065] S4. Arrange the assembled deep foundation deep hole in-situ pore pressure testing device at a preset position and conduct monitoring to obtain a pore pressure time history curve at the monitoring position.

[0066] S41. Lower the deep hole in-situ pore pressure testing device for deep foundation to the designated location.

[0067] S42. Calculate the volume difference between the monitoring hole and the volume of the deep foundation deep hole in situ pore pressure test device. After the deep foundation deep hole in situ pore pressure test device is lowered to the designated position, backfill the volume of soil corresponding to the volume difference between the monitoring hole to ensure that the backfill gap is consistent with the properties of the surrounding soil, thereby improving measurement accuracy.

[0068] S43. After backfilling is completed, the deep foundation deep hole in-situ pore pressure testing device performs real-time monitoring to obtain the pore pressure time history curve at the monitoring location.

[0069] Before formal monitoring during the lowering and stationary process of the deep foundation deep hole in-situ pore pressure testing device, the pore pressure sensor 3 measures data and collects water level data at a frequency of 10 Hz to check for problems such as sensor failure and damage. The pore pressure sensor 3 transmits the data to the external collector, which then saves the data in the computer's data storage system.

[0070] The method for obtaining the horizontal consolidation coefficient of foundation in this embodiment is implemented by the following steps:

[0071] D1. Construct a formation numerical model on a computer using numerical simulation analysis software to obtain a completed formation numerical model; obtain a number of influencing factors, and input all of the influencing factors into the completed formation numerical model to obtain a formation numerical model including all of the influencing factors.

[0072] Influencing factors include but are not limited to seepage, high-pressure water spraying from the machine, hole expansion, extrusion and vibration energy input.

[0073] D11. Grid the monitoring site and construct a stratum numerical model using finite difference grids in the numerical simulation analysis software. Set the size of the monitoring site, grid size, and constitutive model in the stratum numerical model, as well as the boundary conditions and initial conditions of the stratum numerical model.

[0074] The initial conditions of the formation numerical model are determined according to different influencing factors; the boundary conditions of the formation numerical model are determined according to the site conditions.

[0075] D12. Obtain the preliminary construction geological survey data to determine the soil parameters such as the ground stratum distribution, density, Poisson's ratio and permeability coefficient, and input the soil parameters into the stratum numerical model to obtain the completed stratum numerical model.

[0076] Furthermore, the rationality of the model parameter settings is determined through indoor tests and on-site construction data analysis. In specific implementation, for example, a section of the measured pore pressure time history curve without interference is taken to compare the pore pressure time history curve in the numerical model to see how well it matches.

[0077] D13. Determine multiple factors affecting pore pressure changes during construction based on field data and construction methods, and input all influencing factors into the formation numerical model to obtain a formation numerical model that includes all influencing factors.

[0078] D2. Use an in-situ pore pressure test device in a deep foundation deep hole to monitor the test location and obtain a pore pressure time history curve at the test location. Obtain an interference-free pore pressure time history curve based on a formation numerical model that includes all influencing factors and the pore pressure time history curve at the test location.

[0079] In specific implementation, the pore pressure time history curve mainly selects the time history curve of the pore pressure dissipation stage to obtain the horizontal consolidation coefficient of the foundation.

[0080] D21. Conduct pore pressure test simulation experiments for each influencing factor in the formation numerical model containing all influencing factors, and obtain the pore pressure time history curve of a single influencing factor corresponding to each influencing factor.

[0081] D22. Assemble the deep foundation deep hole in-situ pore pressure test device and place it at the preset position to monitor and obtain the pore pressure time history curve at the test location.

[0082] D23. Subtract the pore pressure time history curves of all individual influencing factors from the pore pressure time history curve measured at the position to be measured, and finally obtain the pore pressure time history curve without interference.

[0083] D3. Obtain the horizontal consolidation coefficient of the foundation based on the undisturbed pore pressure time history curve.

[0084] The horizontal consolidation coefficient of the foundation is obtained by the following formula of the pore pressure time history curve without interference:

[0085]

[0086] Where u is the pore pressure, t is the dissipation time, C his the horizontal consolidation coefficient of the foundation, and r is the radial distance between the construction center and the pore pressure sensor 3.

[0087] In a specific implementation, the above formula of the pore pressure time history curve without interference is mainly the time history curve of the pore pressure dissipation period.

[0088] The device and method of the present invention place a pore pressure sensor 3 at a specified burial depth. The design and assembly of the device take into account factors such as internal and external hole cross-connections, sensor filtration protection, survivability in harsh construction environments, and long-term service. This invention achieves the beneficial effects of maintaining a normal pore pressure response after long-term service and removing unaffected pore pressure time history curves from subsequent static and dynamic coupled data analysis.

[0089] The device and method of the present invention can accurately and quickly measure the pore pressure time-history curve of a deep overburden layer. The device has good working performance in an ultra-deep underground environment. The horizontal consolidation coefficient obtained by the in-situ pore pressure data through a reasonable data analysis method has a clear physical meaning and high accuracy. This solves the problem of conventional pore pressure measurement equipment working normally for a long time in an ultra-deep environment and accurately obtaining parameters such as the horizontal consolidation coefficient of the foundation.

[0090] The above embodiments are merely preferred embodiments for the purpose of fully illustrating the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

Claims

1. An in-situ pore pressure testing device for deep foundation deep holes, characterized by: The invention comprises a plurality of extension pipes and an in-situ pore pressure monitoring pipe (1); the plurality of extension pipes are threadedly connected in sequence to form a long connecting pipe, and the in-situ pore pressure monitoring pipe (1) is threadedly connected to the head of the long connecting pipe; each of the extension pipes is a hollow steel pipe, and the two ends of the hollow steel pipe are respectively a closed end provided with an external thread and an open end provided with an internal thread; the open ends and the closed ends of the plurality of extension pipes are threadedly connected in sequence to form a long connecting pipe; each of the in-situ pore pressure monitoring pipe (1) comprises a hollow monitoring steel pipe and a pore pressure sensor (3); the two ends of the monitoring steel pipe are respectively a sealed end provided with an external thread and an open end provided with an internal thread, and the open end of the in-situ pore pressure monitoring pipe (1) is threadedly connected to the closed end of the extension pipe at one end of the long connecting pipe; the pore pressure sensor (3) is arranged in the middle of the monitoring steel pipe, and the space between the pore pressure sensor (3) and the inner wall of the monitoring steel pipe is filled with quartz sand.

2. The deep foundation deep hole in-situ pore pressure testing device according to claim 1 is characterized by: The in-situ borehole pressure monitoring pipe (1) further comprises gauze and a supporting borehole plug pad (2); a plurality of flower holes and a wiring hole are opened on the outer circumference of the monitoring steel pipe, the supporting borehole plug pad (2) is installed on the wiring hole, and the signal line of the borehole pressure sensor (3) is led out to the outside of the in-situ borehole pressure monitoring pipe (1) through the supporting borehole plug pad (2); a layer of gauze is wrapped around the outer circumference of the monitoring steel pipe wrapped with gauze to form an anti-filter layer, and the led-out signal line is wrapped around the outer circumference of the monitoring steel pipe wrapped with gauze and the outer circumference of the long connecting pipe and is finally electrically connected to the collector in a spiral ascending wiring manner.

3. A method for assembling and monitoring the deep foundation deep hole in-situ pore pressure testing device according to claims 1-2, characterized in that: S1. Drill a hole in the monitoring area. After drilling, pour clean water into the hole until clean water returns to the hole; then stop pouring; S2. Determine the number of extension tubes according to the required monitoring depth, and thread the open and closed ends of multiple extension tubes together to form a long connecting tube; S3, saturating the pore pressure sensor (3) and assembling the deep foundation deep hole in-situ pore pressure testing device; S4. Arrange the assembled deep foundation deep hole in-situ pore pressure testing device at a preset position and perform monitoring to obtain a pore pressure time history curve at the monitoring position.

4. The assembly and monitoring method of the deep foundation deep hole in-situ pore pressure testing device according to claim 3 is characterized in that: The step S3 is specifically as follows: S31, remove the filter (31) on the head of the pore pressure sensor (3), and soak the filter (31) and the pore pressure sensor (3) without the filter (31) in clean water for several hours to saturate; S32, install the saturated filter (31) on the head of the pore pressure sensor (3), and place the saturated pore pressure sensor (3) with the filter (31) in the middle of the monitoring steel pipe, and lead the data line through the supporting hole plug pad (2); S33, adding quartz sand to the monitoring steel pipe until it is full, and wrapping the outer periphery of the monitoring steel pipe with gauze to form an anti-filter layer, and spirally wrapping the data line of the pore pressure sensor (3) on the gauze surface of the outer periphery of the monitoring steel pipe, and protecting and fixing the data line with a tie and adhesive tape to obtain an in-situ pore pressure monitoring pipe (1); S34. Connect the in-situ pore pressure monitoring tube (1) to the head of the long connecting tube, and spirally wind the data line of the pore pressure sensor (3) around the outer circumference of the long connecting tube, and finally electrically connect it to the collector to obtain an assembled deep foundation deep hole in-situ pore pressure testing device.

5. The assembly and monitoring method of the deep foundation deep hole in-situ pore pressure testing device according to claim 3 is characterized in that: The step S4 is specifically as follows: S41, lowering the deep foundation deep hole in-situ pore pressure testing device to a designated location; S42, calculating the volume difference between the monitoring hole and the volume of the deep foundation deep hole in-situ pore pressure testing device, and backfilling the area between the deep foundation deep hole in-situ pore pressure testing device and the monitoring hole with a volume corresponding to the volume difference after the deep foundation deep hole in-situ pore pressure testing device is lowered to a designated location; S43. After backfilling is completed, the deep foundation deep hole in-situ pore pressure testing device performs real-time monitoring to obtain a pore pressure time history curve at the monitoring position.

6. A method for obtaining the horizontal consolidation coefficient of a foundation for implementing the deep foundation deep hole in-situ pore pressure testing device according to claims 1-2, characterized in that: D1. Constructing a formation numerical model using numerical simulation analysis software to obtain a completed formation numerical model; obtaining a number of influencing factors, and inputting all of the influencing factors into the completed formation numerical model to obtain a formation numerical model that includes all of the influencing factors; D2. Using the deep foundation deep hole in-situ pore pressure testing device to monitor the position to be tested, obtaining a pore pressure time history curve at the position to be tested, and obtaining an interference-free pore pressure time history curve based on a formation numerical model including all influencing factors and the pore pressure time history curve at the position to be tested; D3. Obtain the horizontal consolidation coefficient of the foundation based on the undisturbed pore pressure time history curve.

7. The method for obtaining the horizontal consolidation coefficient of a deep foundation deep hole in-situ pore pressure testing device according to claim 6, characterized in that: The step D1 is specifically as follows: D11. Grid the monitoring site and construct a stratum numerical model using a finite difference grid in the numerical simulation analysis software. Set the monitoring site size, grid size, and constitutive model in the stratum numerical model, as well as the boundary conditions and initial conditions of the stratum numerical model. D12. Obtain pre-construction geological survey data to determine soil parameters such as ground stratum distribution, density, Poisson's ratio, and permeability coefficient, and input the soil parameters into the stratum numerical model to obtain a completed stratum numerical model; D13. Determine multiple factors affecting pore pressure changes during construction based on field data and construction methods, and input all influencing factors into the formation numerical model to obtain a formation numerical model that includes all influencing factors.

8. The method for obtaining the horizontal consolidation coefficient of a deep foundation deep hole in-situ pore pressure testing device according to claim 6, characterized in that: The step D2 is specifically as follows: D21. Conduct pore pressure test simulation experiments for each influencing factor in the formation numerical model that includes all influencing factors, and obtain the pore pressure time history curve corresponding to each individual influencing factor; D22, assembling the deep foundation deep hole in-situ pore pressure testing device and placing it at a preset location, and monitoring and obtaining a pore pressure time history curve at the location to be tested; D23. Subtract the pore pressure time history curves of all individual influencing factors from the pore pressure time history curve measured at the position to be measured, and finally obtain the pore pressure time history curve without interference.

9. The method for obtaining the horizontal consolidation coefficient of a deep foundation deep hole in-situ pore pressure testing device according to claim 6, characterized in that: The influencing factors include seepage, high-pressure water ejected from the machine, hole expansion, extrusion and vibration energy input.

10. The method for obtaining the horizontal consolidation coefficient of a deep foundation deep hole in-situ pore pressure testing device according to claim 6, characterized in that: The horizontal consolidation coefficient of the foundation is obtained by the following formula of the pore pressure time history curve without interference: Where u is the pore pressure, t is the dissipation time, C h is the horizontal consolidation coefficient of the foundation, and r is the radial distance between the construction center and the pore pressure sensor (3).

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