Well wall thickness determination method and device for deep soil wellbore and medium

Abstract

The invention discloses a method and device for determining the well wall thickness of a deep soil wellbore and a medium, and relates to the field of geotechnical engineering of the civil engineering disciplinary .The method comprises the steps that a high-pressure-side pressure coefficient creep test is conducted on deep soil through a high-pressure-side pressure coefficient consolidation apparatus; the curve of the deep soil lateral pressure coefficient changing along with different depths and the curve of the deep soil lateral pressure coefficient changing along with different consolidation pressures are obtained; the curve of the deep soil side pressure coefficient changing along with different depths and the curve of the deep soil side pressure coefficient changing along with different consolidation pressures are fitted, an expression of the curve of the deep soil side pressure coefficient changing along with the depths and the consolidation pressures is obtained, and the expression is applied to calculation of a horizontal ground pressure value acting on the well wall. The maximum value of the horizontal ground pressure acting on the well wall is obtained; and according to the maximum value of the horizontal ground pressure acting on the well wall, the minimum well wall thickness allowed to be designed by the shaft is obtained. The method can improve the precision of determining the thickness of the shaft of the deep soil.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of geotechnical engineering, and particularly relates to a method and device for determining the thickness of a shaft wall of a deep soil shaft and a medium. BACKGROUND

[0002] The engineering practice of coal mine construction shows that the physical and mechanical properties of soil change significantly with the increase of depth, and the mechanical properties of deep and shallow soil, especially cohesive soil, have significant differences. In view of the characteristics of deep geotechnical engineering, it is extremely necessary to use a suitable test method to study the mechanical properties of deep soil. The construction of a shaft in deep soil is a big problem. In order to ensure the safety and economy of the shaft, the thickness of the shaft should be reasonably determined.

[0003] However, there is a lack of a method for accurately determining the thickness of the shaft in the prior art. SUMMARY

[0004] Therefore, it is necessary to provide a method and device for determining the thickness of a shaft wall of a deep soil shaft and a medium to solve the above technical problems. The method can improve the accuracy of determining the thickness of the shaft of deep soil.

[0005] The present application adopts the following technical solutions: The present application provides a method for determining the thickness of a shaft wall of a deep soil shaft, comprising: Performing a high-pressure lateral pressure coefficient consolidation test on the deep soil by using a high-pressure lateral pressure coefficient consolidation instrument to obtain a curve of the lateral pressure coefficient of the deep soil changing with different depths and a curve of the lateral pressure coefficient of the deep soil changing with different consolidation pressures; the high-pressure lateral pressure coefficient consolidation instrument can control the deep soil to have no lateral deformation; Fitting the curve of the lateral pressure coefficient of the deep soil changing with different depths and the curve of the lateral pressure coefficient of the deep soil changing with different consolidation pressures to obtain an expression of the curve of the lateral pressure coefficient of the deep soil changing with the depth and the consolidation pressure; Applying the expression of the curve of the lateral pressure coefficient of the deep soil changing with the depth and the consolidation pressure to the calculation of the horizontal ground pressure value acting on the shaft wall to obtain the maximum value of the horizontal ground pressure acting on the shaft wall; According to the maximum value of the horizontal ground pressure acting on the shaft wall, the minimum shaft wall thickness allowed in the design is obtained.

[0006] Preferably, the high-pressure lateral pressure coefficient consolidation instrument comprises a pressurizing weight, a pressurizing lever, a base, a computer data acquisition system, a pressure display instrument, a rigid container, a lateral pressure sensor, an axial pressure sensor, a pressurizing piston, a water-permeable stone and a pore water pressure sensor. A rigid container is placed on a base for placing deep soil; water permeable stones are placed on the deep soil respectively; a lateral pressure sensor and an axial pressure sensor are arranged on the side of the rigid container; a pore water pressure sensor is arranged on the bottom of the rigid container; A pressurizing piston is arranged above the water permeable stone on the upper part of the deep soil and is connected with the rigid container; A pressurizing lever is arranged above the pressurizing piston; the pressurizing lever is provided with a pressurizing weight; The lateral pressure sensor, the axial pressure sensor and the pore water pressure sensor are respectively connected with a computer data acquisition system and a pressure display instrument; The pressurizing weight and the pressurizing lever are used for applying axial pressure to the deep soil; The lateral pressure sensor, the axial pressure sensor and the pore water pressure sensor are respectively used for collecting lateral earth pressure of the deep soil, axial earth pressure of the deep soil and pore water pressure of the deep soil; The pressure display instrument is used for displaying lateral earth pressure of the deep soil, axial earth pressure of the deep soil and pore water pressure of the deep soil; The computer data acquisition system is used for recording and analyzing lateral earth pressure of the deep soil, axial earth pressure of the deep soil and pore water pressure of the deep soil.

[0007] Preferably, the high-pressure lateral pressure coefficient consolidation instrument is used to perform a high-pressure lateral pressure coefficient creep test on the deep soil to obtain a curve of the lateral pressure coefficient of the deep soil changing with different depths and a curve of the lateral pressure coefficient of the deep soil changing with different consolidation pressures, and the high-pressure lateral pressure coefficient creep test specifically comprises the following steps: The pressurizing weight and the pressurizing lever are used to apply stepwise increasing axial pressure to the deep soil to simulate the overlying soil pressure of the deep soil at different depths; After the axial deformation is stable under each level of pressure, the lateral earth pressure of the deep soil, the axial earth pressure of the deep soil and the pore water pressure of the deep soil under each level of pressure are recorded respectively; The difference between the axial earth pressure and the pore water pressure is determined as the consolidation pressure of the deep soil; According to the consolidation pressure and the lateral earth pressure, the curve of the lateral pressure coefficient of the deep soil changing with different depths and the curve of the lateral pressure coefficient of the deep soil changing with different consolidation pressures are obtained.

[0008] Preferably, when the deep soil is clay, the expression of the curve of the lateral pressure coefficient of the deep soil changing with the depth and the consolidation pressure is as follows: ; wherein, a, b, c are dimensionless test parameters related to soil properties, γ is the unit weight of the soil, H is the depth of the calculation point, is the pressure intensity of the consolidation pressure of the clay acting on the clay, This represents the coefficient of deep soil lateral pressure in clay.

[0009] Preferably, when the deep soil is sandy, the expression for the curve of the deep soil lateral pressure coefficient as a function of depth and consolidation pressure is as follows: ; in, The deep lateral earth pressure coefficient of sandy soil. a, b For dimensionless test parameters related to soil properties, γ The weight of soil. H To calculate the depth of the point, It is the pressure exerted on the sand by the consolidation pressure.

[0010] Preferably, the formula for calculating the maximum horizontal ground pressure acting on the wellbore is: ; in, P H For calculation points H Horizontal ground pressure at that location H= , For the first i The natural unit weight of the soil layers. For the first i The thickness of the soil layer, K 0 For calculation points H The coefficient of deep soil lateral pressure at that location. n This represents the number of soil layers.

[0011] Preferably, the formula for calculating the wellbore thickness is: ; in, R The radius of the shaft excavation. The allowable compressive stress of the wellbore material. P max This represents the maximum horizontal ground pressure acting on the wellbore. d This refers to the well wall thickness.

[0012] Preferably, the method further includes: Based on the calculation method of horizontal ground pressure in deep soil, combined with equilibrium conditions and Huke's law, the vertical additional stress of the well wall is obtained; Obtain the critical value of the deep soil layer thickness corresponding to the maximum vertical additional stress on the well wall; When the thickness of the deep soil layer exceeds the critical value of the deep soil layer thickness, vertical instability is determined; vertical instability indicates well wall rupture. Vertical stability is determined when the thickness of the deep soil layer is less than or equal to the critical value of the deep soil layer thickness. Vertical stability indicates that the well wall is safe.

[0013] The application provides a deep soil shaft well thickness determination device, comprising: A test module is configured to perform high-pressure lateral pressure coefficient creep tests on deep soil by using a high-pressure lateral pressure coefficient consolidation instrument to obtain a curve of deep soil lateral pressure coefficient change with different depths and a curve of deep soil lateral pressure coefficient change with different consolidation pressures; the high-pressure lateral pressure coefficient consolidation instrument can control deep soil to have no lateral deformation; A fitting module is configured to fit the curve of deep soil lateral pressure coefficient change with different depths and the curve of deep soil lateral pressure coefficient change with different consolidation pressures to obtain an expression of the curve of deep soil lateral pressure coefficient change with depths and consolidation pressures; A first determination module is configured to apply the expression of the curve of deep soil lateral pressure coefficient change with depths and consolidation pressures to calculation of a horizontal ground pressure value acting on a well wall to obtain a maximum value of the horizontal ground pressure acting on the well wall; A second determination module is configured to obtain a minimum well wall thickness allowed for design of a shaft according to the maximum value of the horizontal ground pressure acting on the well wall.

[0014] The application provides a computer readable storage medium, wherein the storage medium stores a computer program, and the computer program is executed by a processor to implement the deep soil shaft well thickness determination method.

[0015] The application provides a computer device, comprising a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor implements the deep soil shaft well thickness determination method when executing the program.

[0016] The above at least one technical scheme adopted by the application can achieve the following beneficial effects: The high-pressure lateral pressure coefficient creep tests on deep soil by using the high-pressure lateral pressure coefficient consolidation instrument can obtain the curve of deep soil lateral pressure coefficient change with different depths and the curve of deep soil lateral pressure coefficient change with different consolidation pressures, which helps to understand the mechanical properties of deep soil; the fitting of the curve of deep soil lateral pressure coefficient change with different depths and the curve of deep soil lateral pressure coefficient change with different consolidation pressures can obtain the expression of the curve of deep soil lateral pressure coefficient change with depths and consolidation pressures, which reveals the change rule of deep soil lateral pressure coefficient and provides theoretical support and scientific basis for confirmation of the well wall thickness of the shaft; the application of the expression of the curve of deep soil lateral pressure coefficient change with depths and consolidation pressures to calculation of the horizontal ground pressure value acting on the well wall can obtain the maximum value of the horizontal ground pressure acting on the well wall; and the minimum well wall thickness allowed for design of the shaft can be obtained according to the maximum value of the horizontal ground pressure acting on the well wall. The method can improve the accuracy of confirmation of the shaft thickness of deep soil. BRIEF DESCRIPTION OF DRAWINGS

[0017] The drawings used herein for the purpose of providing further understanding of the present application constitute a part of the present application, and the illustrative embodiments of the present application and the description thereof serve to explain the present application, and do not constitute an improper limitation on the present application. In the drawings: Figure 1 A schematic diagram of a method for determining the thickness of the shaft wall of a deep soil shaft is provided in the present application; Figure 2 A high-pressure side pressure coefficient creep test device is provided in the present application; Figure 3 A curve for testing the change of soil sample with consolidation pressure and depth is provided in the present application; Figure 4 A relationship curve diagram of the consolidation process of sand soil side pressure coefficient and the consolidation pressure is provided in the present application; Figure 5 A relationship curve diagram of the consolidation process of sand soil side pressure coefficient and the depth is provided in the present application Figure 6 A schematic diagram of a device for determining the thickness of the shaft wall of a deep soil shaft is provided in the present application; Figure 7 A schematic diagram of a computer device for implementing a method for determining the thickness of the shaft wall of a deep soil shaft is provided in the present application. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present application will be described clearly and completely below in combination with specific embodiments of the present application and corresponding drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0019] The server mentioned in the present application can be a server arranged in a business platform, or a device such as a desktop computer, a notebook computer, etc. capable of executing the scheme of the present application. For the convenience of description, only the server is taken as the execution subject for description below.

[0020] The vertical shaft is the throat of the mine, and the safety and stability of the vertical shaft is very important, especially in some mining areas, the surface soil layer is thick, and the shaft is more prone to cracking, so the stability of the shaft wall is checked before the shaft is put into use.

[0021] The well wall stability checking problem involves the determination of the well wall thickness and the determination of the maximum additional stress of the well bore. Especially, the calculation of the well wall thickness is a very key work in the shaft well bore design, especially in recent years, the occurrence of some shaft damage accidents in some areas causes the design and research departments to pay attention to the calculation of the well wall thickness. The well wall thickness is determined by calculation and engineering analogy method according to the well wall structure and material, the shaft ground pressure, the temporary load (such as freezing tension, hanging force and grouting pressure, etc.) during the construction of the well bore, the additional load applied to the well wall by the well head structure (such as the well tower and the well head room, etc.), etc. Among them, the shaft ground pressure is the main load acting on the well wall and is the main basis for designing the well wall. The shaft ground pressure distribution law is related to many factors such as the properties of rock (soil) body, stratum environment and occurrence, vertical depth, shaft excavation method, well wall structure form, etc. And the thickness of the well wall of the topsoil section is mainly determined by the size of the horizontal ground pressure.

[0022] Therefore, the prior art lacks a method for optimizing the confirmation of the well bore thickness of deep soil.

[0023] The technical solutions provided by the embodiments of the present application are described in detail below with reference to the drawings.

[0024] Figure 1 The present application is a method for determining the well wall thickness of a deep soil well bore, and the specific steps include the following steps: S101: Perform high-pressure lateral pressure coefficient creep test on the deep soil by using a high-pressure lateral pressure coefficient consolidation instrument to obtain the curves of the lateral pressure coefficient of the deep soil changing with different depths and the curves of the lateral pressure coefficient of the deep soil changing with different consolidation pressures; the high-pressure lateral pressure coefficient consolidation instrument can control the deep soil to not produce lateral deformation.

[0025] In an exemplary embodiment, the high-pressure lateral pressure coefficient consolidation apparatus includes a pressure weight, a pressure lever, a base, a computer data acquisition system, a pressure display instrument, a rigid container, a lateral pressure sensor, an axial pressure sensor, a pressure piston, permeable stones, and a pore water pressure sensor. The rigid container, placed on the base, is used to hold deep soil. Permeable stones are placed above and below the deep soil. The rigid container has a lateral pressure sensor and an axial pressure sensor on its side. The bottom of the rigid container has a pore water pressure sensor. The pressure piston is placed above the permeable stones in the deep soil and is connected to the rigid container. The pressure lever is placed above the pressure piston. The pressure lever is equipped with a pressure weight. The lateral pressure sensor... The lateral pressure sensor, axial pressure sensor, and pore water pressure sensor are connected to the computer data acquisition system and the pressure display instrument, respectively; a rigid container is used to hold the deep soil; pressure weights and pressure levers are used to apply axial pressure to the deep soil; the lateral pressure sensor, axial pressure sensor, and pore water pressure sensor are used to collect the lateral earth pressure, axial earth pressure, and pore water pressure of the deep soil, respectively; the pressure display instrument is used to display the lateral earth pressure, axial earth pressure, and pore water pressure of the deep soil; the computer data acquisition system is used to record and analyze the lateral earth pressure, axial earth pressure, and pore water pressure of the deep soil.

[0026] Specifically, axial and lateral pressures are applied to the deep soil. The lateral pressure is a fixed value of 20 MPa, while the axial pressure is applied in progressively increasing increments using a pressure lever and weights. In this invention, the apparatus for the high-pressure lateral pressure coefficient creep test is a high-pressure creep K0 consolidation triaxial apparatus that considers progressive loading, such as... Figure 2 (in) a As shown in the figure, 1 is the pressure weight, 2 is the pressure lever, 3 is the base, 4 is the computer data acquisition system, and 5 is the axial pressure, lateral pressure, and pore water pressure display instrument. Figure 2 As shown in Figure (b), 6 is the pressurized container, 7 is the lateral pressure sensor, and 8 is the axial pressure sensor. Figure 2As shown in Figure (c), 9 is the pressure piston, 10 is the permeable stone, 11 is the test soil sample, and 12 is the pore water pressure sensor. The rigid container is placed on the base. The rigid container is forged and cut from a stainless steel round steel, which has high rigidity and good pressure resistance. The pressure piston is located on the upper part of the rigid container, and pressure sensors are located on the side walls and bottom. The test sample is placed inside. An O-ring seal is provided between the pressure piston and the rigid container. The permeable stone is placed between the pressure piston and the test sample. The pressure device on the upper part of the pressure piston uses a lever with a lever ratio of 1:30. Pressure weights are provided on the side, and the lever pressure end deflects... The small size meets the test requirements; the rigid container's sidewalls and bottom are connected to the pressure display instrument via lateral pressure sensors, axial pressure sensors, and pore water pressure sensors. The instrument is based on a microcontroller and equipped with high-performance steel wire exciter circuits. During use, the excitation circuit excites the steel wire to vibrate, and the microcomputer quickly and accurately measures the frequency; the test sample is placed inside the rigid container, and permeable stones are placed at the top and bottom of the test sample to ensure that the sample is saturated with water during loading; the lateral pressure sensors, axial pressure sensors, and pore water pressure sensors are respectively connected to the pressure display instrument and the computer data acquisition system.

[0027] In an exemplary embodiment, a high-pressure lateral pressure coefficient creep test is conducted on deep soil using a high-pressure lateral pressure coefficient consolidation apparatus to obtain curves showing the variation of the deep soil lateral pressure coefficient with different depths and curves showing the variation of the deep soil lateral pressure coefficient with different consolidation pressures. Specifically, this includes: applying progressively increasing axial pressure to the deep soil using pressure weights and levers to simulate the overburden pressure on the deep soil at different depths; after the axial deformation stabilizes under each pressure level, recording the lateral earth pressure, axial earth pressure, and pore water pressure of the deep soil under each pressure level; determining the difference between the axial earth pressure and the pore water pressure as the consolidation pressure of the deep soil; and obtaining curves showing the variation of the deep soil lateral pressure coefficient with different depths and curves showing the variation of the deep soil lateral pressure coefficient with different consolidation pressures based on the consolidation pressure and lateral earth pressure.

[0028] Taking a soil sample as an example, the process of the high-pressure side pressure coefficient creep test of the present invention is as follows: 1. Open the lid of the rigid container.

[0029] 2. Place a permeable stone at the bottom of a rigid container, apply a layer of lubricating oil to the surface of the prepared test soil sample, and then place it on the permeable stone.

[0030] 3. Place a permeable stone on top of the soil sample and place the pressure piston on top of the permeable stone to connect with the rigid container.

[0031] 4. Gently push the upper lever to make it make close contact with the pressure piston to prevent it from falling off after the pressure is applied.

[0032] 5. Connect the lateral pressure sensor, axial pressure sensor, and pore water pressure sensor to the computer-connected intelligent testing instrument.

[0033] 6. Using a step-by-step loading method, the axial pressure on the soil sample is gradually increased to simulate the overburden pressure on the soil sample at different depths.

[0034] 7. After the axial deformation stabilizes under each pressure level, record the consolidation pressure. and lateral stress This allows us to calculate the lateral pressure coefficients of the test soil samples at different depths.

[0035] The technical parameters and performance of this invention are as follows: Lateral pressure range: 0~20Mpa.

[0036] Axial pressure range: The axial pressure is a constant value.

[0037] Soil sample testing depth: 0~800m.

[0038] Laboratory creep tests mainly employ two methods: the stepped loading method and the constant load method. The stepped loading method applies a constant axial pressure to a single specimen, and after the compression deformation has stabilized, the next level of load is applied. The constant load method uses a set of identical specimens, applying different levels of constant load and observing the changes in deformation or deformation rate over time under each level of constant load. The purpose of this invention is to determine the static lateral pressure coefficient of soil samples after axial creep stabilization at the K0 state and the microstructure of the soil samples after axial creep stabilization at each pressure level. Therefore, for clay samples, a step-by-step loading method was used, recording the static lateral pressure coefficient K0 value after the soil sample deformation stabilized at each load level.

[0039] The test soil samples were selected from undisturbed soil samples from a deep mine shaft, buried at a depth of 300–700 m. This invention used a total of 6 groups of clay samples and 5 groups of sand samples, with a test size of 61.8 mm. 150mm. Table 1 shows the basic physical and mechanical properties of the clay sample, and Table 2 shows the basic physical and mechanical properties of the sand sample. Before the test, care should be taken to carefully cut the soil sample with a soil cutting ring, and a layer of lubricating oil should be evenly applied to the surface of the soil sample before putting it into the container to control the soil sample from losing water due to changes in the external environment during the K0 consolidation process.

[0040] Table 1

[0041] Table 2

[0042] The experiment was conducted at six stress levels, with 6 stress levels applied to the soil samples respectively. Mpa 8Mp a, 10 Mpa 12 Mpa 14 Mpa 16 Mpa Axial pressure, simulating soil samples at 300 m 400 m 500 m 600 m 700 m 800 m The overlying soil pressure at the time, after axial deformation stabilizes under various pressures, the consolidation pressure is recorded. and lateral stress This allows us to determine the lateral pressure coefficients corresponding to different depths of the test soil sample. The high-pressure K0 test for cohesive soil must consider the effect of creep.

[0043] S102: Fit the curves of deep soil lateral pressure coefficient with different depths and the curves of deep soil lateral pressure coefficient with different consolidation pressures to obtain the expression of the curves of deep soil lateral pressure coefficient with depth and consolidation pressure.

[0044] In an exemplary embodiment, when the deep soil is clay, the expression for the curve of the deep soil lateral pressure coefficient as a function of depth and consolidation pressure is shown in formula (1): (1); in, a, b, c These are dimensionless test parameters related to soil properties, determined experimentally. γ The weight of soil. H To calculate the depth of the point, This refers to the consolidation pressure of clay acting on the clay. This represents the coefficient of lateral pressure in deep soil.

[0045] Specifically, high-pressure K0 creep tests were conducted on three groups of soil samples, and the curves showing the variation of K0 values ​​with different consolidation pressures and depths were obtained, as shown below. Figure 3 As shown, the curve of K0 value changing with depth is an exponential function. Figure 3 (in) a The figure shows the curve of K0 value of sample 1 as a function of consolidation pressure P. Figure 3 Figure (b) shows the curve of K0 value of sample 1 as a function of depth H. Figure 3 Figure (c) shows the curve of K0 value of sample 2 as a function of consolidation pressure P. Figure 3 Figure (d) shows the curve of K0 value of sample 2 as a function of depth H. Figure 3 Figure (e) shows the curve of K0 value of sample 3 as a function of consolidation pressure P. Figure 3Figure (f) shows the curve of K0 value of sample 3 as a function of depth H. In the depth range of 300-500m, the K0 value varies greatly, but after the depth exceeds 500m, K0 remains basically unchanged.

[0046] right Figure 3 The curves in the figure are fitted to obtain the calculation method of the lateral pressure coefficient of clay as formula (1), where a, b, and c are dimensionless test parameters related to soil properties, determined by experiments. The clay test results of this invention are analyzed. a =0.79~0.82, b =-1.76, c =-0.47, applicable H ≥300m, γ The unit weight of soil is 1. , H To calculate the depth of the point, the unit is... m , The consolidation pressure is the pressure exerted on the clay, measured in units of 1. .

[0047] Specifically, if the calculation point is located in a multi-layered clay layer, the calculation method for the lateral pressure coefficient of clay using the layered summation method is shown in formula (2): (2); in, a, b, c These are dimensionless test parameters related to soil properties. H ≥300m, For the first i The unit weight of layered clay, hi For the first i The thickness of the clay layer, For pressure, This represents the coefficient of deep lateral earth pressure in clay. n This refers to the number of clay layers.

[0048] For the clay used in this invention, a = 0.79 to 0.82, b = -1.76, and c = -0.47.

[0049] In an exemplary embodiment, when the deep soil is sandy, the expression for the curve of the deep soil lateral pressure coefficient as a function of depth and consolidation pressure is shown in formula (3): (3); in, The deep lateral earth pressure coefficient of sandy soil. a, b These are dimensionless test parameters related to soil properties, determined by experiments. γ The weight of soil. H To calculate the depth of the point, It is the pressure exerted on the sand by the consolidation pressure.

[0050] Specifically, high-pressure K0 consolidation tests were conducted on five groups of sand samples, and the curves showing the variation of K0 values ​​with different consolidation pressures and depths were obtained, such as... Figure 4 The curve shows the relationship between the consolidation process and consolidation pressure of sand. Figure 5 This is a curve showing the relationship between the consolidation process and depth of sand. Figure 4 and Figure 5 The symbols ◆, ■, ▲, Χ, and ※ represent the burial depths of the test sand samples as 341.80m~349.40m, 350.40m~360.00m, 379.60m~382.90m, 388.00m~391.10m, and 481.30m~483.30m, respectively.

[0051] from Figure 5 It was found that the K0 value changes linearly with depth during the consolidation process of deep sand, and the K0 value remains between 0.1 and 0.2. By fitting the curve of K0 change with depth during the consolidation process of deep sand, the calculation method of the lateral pressure coefficient of sand is obtained as formula (3), where, a b are dimensionless test parameters related to soil properties, which can be determined by experiments. Based on the statistical results of the test on sandy soil according to the present invention, a =0.13~0.16, b =0.002, applicable H ≥300m, r The unit weight of soil is 1. , H To calculate the depth of the point, the unit is... m , The consolidation pressure of sand is the pressure exerted on the sand, and the unit is 1. .

[0052] Specifically, if the calculation point is located in a multi-layered sandy soil layer, the calculation method for the lateral pressure coefficient of clay using the layered summation method is shown in formula (4): (4); in, a, b These are dimensionless test parameters related to soil properties. H ≥300m, For the first i The unit weight of the soil layer, For the first i The thickness of the soil layer, n This refers to the number of clay layers.

[0053] For the sand used in the experiments of this invention, it is recommended that a =0.13~0.16, b =0.002.

[0054] The above experiments show that: (1) The high-pressure K0 consolidation test device developed is simple to operate, easy to pressurize, and has low testing cost. It can better simulate the characteristics of the soil around the deep well wall.

[0055] (2) High-pressure K0 creep tests on deep clay showed that the K0 value of deep clay exhibited an exponential distribution with depth, with significant variations in the K0 value within the burial depth range of 300–500 m, while remaining essentially unchanged beyond 500 m. In contrast, the K0 value of deep sand showed a linear distribution with depth, remaining between 0.1 and 0.2. The test results indicate that the characteristics of deep soils are significantly different from those of shallow soils.

[0056] Specifically, taking a mine inspection hole as an example, the topsoil section of the shaft is 566.20m thick. Table 3 shows the unit weight and thickness of each soil layer.

[0057] Table 3

[0058] S103: Apply the expression of the curve of deep soil lateral pressure coefficient with depth to the calculation of the horizontal ground pressure value acting on the well wall to obtain the maximum value of the horizontal ground pressure acting on the well wall.

[0059] In an exemplary embodiment, the formula for calculating the maximum horizontal ground pressure acting on the wellbore is shown in formula (5): (5); in, P H For calculation points H Horizontal ground pressure at that location H= , For the first i The natural unit weight of the soil layers. For the first i The thickness of the soil layer, K 0 To calculate the deep soil lateral pressure coefficient, n This represents the number of soil layers.

[0060] Specifically, in this invention, the K0 of the clay is determined by creep test under spatial axisymmetric stress state, which is consistent with the stress characteristics of the soil surrounding the well wall. Therefore, the horizontal ground pressure is determined by the K0 calculation formula in this paper, which is more consistent with the actual stress state. Based on the mechanism of horizontal ground pressure under self-weight stress field conditions, the layered summation method is used to calculate the horizontal ground pressure of deep soil according to formula (5).

[0061] Specifically, based on Lamé's formula, the wellbore inner diameter is taken as 8m, and the allowable compressive stress of the wellbore material is 29.4. MpaThe topsoil thickness is 566m. Using formula (5), the maximum horizontal ground pressure acting on the well wall is calculated as follows: .

[0062] S104: Based on the maximum horizontal ground pressure acting on the well wall, obtain the minimum allowable well wall thickness for well design.

[0063] In an exemplary embodiment, the wellbore thickness is calculated as shown in formula (6): (6); in, R The radius of the shaft excavation. The allowable compressive stress of the wellbore material. P max This represents the maximum horizontal ground pressure acting on the wellbore. d This refers to the well wall thickness.

[0064] For example, in S103 At that time, the well wall thickness is calculated according to formula (6), and the result is obtained. ,Pick d =2.6 m Therefore, the outer diameter of the wellbore is 13.2 mm. m Obviously, the maximum stress on the inner side of the well wall cannot cause the well wall to crack, and the circumferential direction is safe.

[0065] In one exemplary embodiment, the method further includes: Based on the calculation method of horizontal ground pressure in deep soil, combined with equilibrium conditions and Huke's law, the vertical additional stress of the well wall is obtained; Obtain the critical value of the deep soil layer thickness corresponding to the maximum vertical additional stress on the well wall; When the thickness of the deep soil layer exceeds the critical value of the deep soil layer thickness, vertical instability is determined; vertical instability indicates well wall rupture. Vertical stability is determined when the thickness of the deep soil layer is less than or equal to the critical value of the deep soil layer thickness. Vertical stability indicates that the well wall is safe.

[0066] Specifically, based on the well failure characteristics in a certain area, the well walls in the deep water-bearing alluvial topsoil layer are subjected to additional stresses in addition to planar loads. Simulation tests conducted by researchers have proven that these additional stresses not only exist but are also quite significant. Therefore, in the well wall stability calculation under the conditions in this region, the vertical stability of the well wall under the action of vertical additional stresses should also be considered.

[0067] For deep soil, the lateral pressure coefficient is not a constant value, but a function of depth. Based on the lateral pressure coefficient K0 of cohesive soil under high pressure K0 creep conditions determined according to this invention, combined with equilibrium conditions and Hooke's law, the calculation method for calculating the vertical additional stress of the well wall is obtained through mathematical derivation as shown in formula (7): (7); in, b 1 = CπD , , To apply vertical stress to the well wall, E Let be the elastic modulus of the well wall. A Let be the cross-sectional area of ​​the well wall. D The outer diameter of the well shaft. The elastic limit displacement value under shear stress between the soil and the well wall is determined by the interaction shear test. The coefficient of stiffness per unit area for the interaction between the soil and the well wall, along with the strength parameters cohesion and angle of internal friction, can be determined experimentally. The average effective gravity density of the soil layer. z This represents the depth of the soil layer.

[0068] For a certain mine, the maximum depth of the topsoil section is 566.20m. The soil in the range of -483.30m to -566.20m is clay, so there is no additional vertical stress in this depth range. However, the soil in the range of -481.30m to -483.30m is fine sand, which is equivalent to an aquifer. During the construction of the shaft, the aquifer will lose water, which will cause the overlying soil layer to undergo vertical subsidence and displacement. Therefore, the maximum additional stress occurs at -481.30m. Table 4 shows the basic parameters of a certain mine.

[0069] Table 4

[0070] Calculate according to formula (5) z= 481.3 m The maximum additional stress on the wellbore wall at that time was 174.5. MPa This is greater than the strength of the well wall concrete by 29.4. MPa Therefore, the well wall will crack vertically due to the presence of additional stress.

[0071] For a specific mining area or a mining area with similar conditions, the critical thickness of the soil layer that causes the shaft to rupture is determined. To determine the stability of the well wall. If the actual soil layer thickness H at a certain wellbore location is greater than or equal to... If the soil layer thickness is sufficient for the wellbore to fracture, then the wellbore may experience bottom water loss and compression, potentially leading to wellbore wall fracture. When the actual soil layer thickness... H Less than If the calculated structural parameters are met, the wellbore will not experience wellbore wall rupture.

[0072] when When the stress is 0, the additional stress on the well wall reaches its maximum value, and at this time, in formula (7) =0, and the standard strength of the well wall concrete can be calculated by formula (7) and considering the self-weight stress of the well wall, as shown in formula (8): (8); in, The standard strength of the well wall concrete. The density of the well wall concrete. This represents the critical thickness value of the soil layer. A Let be the cross-sectional area of ​​the well wall. , b 1 = CπD .

[0073] A positive root of formula (8) is the critical thickness value of the soil layer, and the calculation method of the critical thickness value of the soil layer is shown in formula (9): (9); in, , These represent the standard strength and density of the well wall concrete, respectively; other symbols have the same meaning as before.

[0074] Take the parameters corresponding to those in Appendix 3. =29.4MPa =0.025MN / m3, calculate the critical soil layer thickness at which wellbore wall rupture occurs. The depth is 158.11m, while the thickness of the overlying soil layer in this mine is 481.30m. m This is greater than the critical soil layer thickness at which wellbore rupture occurs, which is 158.11 mm. m Therefore, the mine is at -158.11. m ~-481.30 m Wellbore wall rupture can occur within a certain depth range, and the wellbore wall thickness should be increased within this range.

[0075] In one exemplary embodiment, the working steps of the present invention are summarized as follows: (1) Experimental study on the variation of static lateral pressure coefficient K0 of deep soil is of great engineering significance for determining the wellbore ground pressure in deep topsoil mining areas.

[0076] (2) Traditional methods for calculating horizontal ground pressure do not conform to the actual stress conditions of well casings. The horizontal ground pressure calculation method studied in this paper takes into account the natural characteristics of the soil and can better simulate the actual conditions. It can not only provide a basis for the safe construction of well casings, but also make the construction of well casings more economical and reasonable.

[0077] (3) When constructing wells in areas with thick topsoil, the loss of water from the aquifer causes additional vertical stress on the well wall. Therefore, when constructing wells in such areas, not only should circumferential stability calculations be performed, but also vertical stability calculations should be performed. Case studies show that well failure in such areas is mainly caused by additional vertical stress.

[0078] When applying the method for determining the wall thickness of a deep earth well provided by this invention, it is not necessary to consider... Figure 1 The steps shown are executed in sequence. The specific execution order of each step can be determined as needed, and this invention does not impose any restrictions on it.

[0079] The above describes a method for determining the wall thickness of a deep soil well shaft according to one or more embodiments of the present invention. Based on the same idea, the present invention also provides a corresponding device for determining the wall thickness of a deep soil well shaft, such as... Figure 6 As shown.

[0080] Figure 6 A schematic diagram of a device for determining the wall thickness of a deep earth well shaft provided by the present invention includes: The test module 601 is used to conduct a high-pressure lateral pressure coefficient creep test on deep soil using a high-pressure lateral pressure coefficient consolidation apparatus to obtain curves showing the change of deep soil lateral pressure coefficient with different depths and curves showing the change of deep soil lateral pressure coefficient with different consolidation pressures; the high-pressure lateral pressure coefficient consolidation apparatus can control the deep soil to prevent lateral deformation. The fitting module 602 is used to fit the curves of the deep soil lateral pressure coefficient with different depths and the curves of the deep soil lateral pressure coefficient with different consolidation pressures, so as to obtain the expression of the curves of the deep soil lateral pressure coefficient with depth and consolidation pressure. The first determining module 603 is used to apply the expression of the curve of the deep soil lateral pressure coefficient changing with depth and consolidation pressure to the calculation of the horizontal ground pressure value acting on the well wall, so as to obtain the maximum value of the horizontal ground pressure acting on the well wall. The second determining module 604 is used to obtain the minimum allowable well wall thickness based on the maximum value of the horizontal ground pressure acting on the well wall.

[0081] Specific limitations regarding the device for determining the wall thickness of a deep soil well shaft can be found in the above-described limitations regarding the method for determining the wall thickness of a deep soil well shaft, and will not be repeated here. Each module in the aforementioned device for determining the wall thickness of a deep soil well shaft can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the operations corresponding to each module.

[0082] The present invention also provides a computer-readable storage medium storing a computer program that can be used to execute the above-described... Figure 1 A method for determining the wall thickness of deep earthen well casings is provided.

[0083] The present invention also provides Figure 7 The schematic diagram of the computer device shown is as follows: Figure 7 As shown, at the hardware level, this computer device includes a processor, internal bus, network interface, memory, and non-volatile memory, and may also include other hardware required for business operations. The processor reads the corresponding computer program from the non-volatile memory into memory and then executes it to achieve the above. Figure 1 A method for determining the wall thickness of deep earthen well casings is provided.

[0084] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the methods described above. Any references to memory, storage, databases, or other media used in the embodiments provided by this invention can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, or optical storage, etc. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0085] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this invention.

Claims

1. A method for determining the wall thickness of a deep earthen well, characterized in that, include: A high-pressure lateral pressure coefficient consolidation apparatus was used to conduct a high-pressure lateral pressure coefficient creep test on deep soil, obtaining curves showing the change of the deep soil lateral pressure coefficient with different depths and curves showing the change of the deep soil lateral pressure coefficient with different consolidation pressures; the high-pressure lateral pressure coefficient consolidation apparatus can control the deep soil to prevent lateral deformation. The curves of the deep soil lateral pressure coefficient with different depths and the curves of the deep soil lateral pressure coefficient with different consolidation pressures are fitted to obtain the expressions for the curves of the deep soil lateral pressure coefficient with depth and consolidation pressure. The expression for the curve of the deep soil lateral pressure coefficient as a function of depth and consolidation pressure is applied to the calculation of the horizontal ground pressure acting on the well wall, and the maximum value of the horizontal ground pressure acting on the well wall is obtained. The minimum allowable wellbore wall thickness is obtained based on the maximum horizontal ground pressure acting on the wellbore wall.

2. The method as described in claim 1, characterized in that, The high-pressure side pressure coefficient consolidation apparatus includes a pressure weight, a pressure lever, a base, a computer data acquisition system, a pressure display instrument, a rigid container, a side pressure sensor, an axial pressure sensor, a pressure piston, a permeable stone, and a pore water pressure sensor. The rigid container is placed on the base for holding deep soil; permeable stones are placed above and below the deep soil respectively; the side of the rigid container is equipped with the side pressure sensor and the axial pressure sensor; the bottom of the rigid container is equipped with the pore water pressure sensor. The pressurized piston is positioned above the permeable stone in the deep soil and is connected to the rigid container; The pressure lever is positioned above the pressure piston; the pressure lever is equipped with a pressure weight. The side pressure sensor, the axial pressure sensor, and the pore water pressure sensor are respectively connected to the computer data acquisition system and the pressure display instrument; The pressure weight and the pressure lever are used to apply axial pressure to the deep soil; The lateral pressure sensor, the axial pressure sensor, and the pore water pressure sensor are used to collect the lateral earth pressure, the axial earth pressure, and the pore water pressure of the deep soil, respectively. The pressure display instrument is used to display the lateral earth pressure, axial earth pressure, and pore water pressure of the deep soil. Computer data acquisition system is used to record and analyze the lateral earth pressure, axial earth pressure, and pore water pressure of deep soil.

3. The method as described in claim 2, characterized in that, The method involves conducting high-pressure lateral pressure coefficient creep tests on deep soil using a high-pressure lateral pressure coefficient consolidation apparatus to obtain curves showing the variation of deep soil lateral pressure coefficient with different depths and curves showing the variation of deep soil lateral pressure coefficient with different consolidation pressures. Specifically, this includes: By using the pressure weights and the pressure levers, an axial pressure that increases gradually is applied to the deep soil, simulating the overburden pressure on the deep soil at different depths. Under each level of pressure, after the axial deformation stabilizes, the lateral earth pressure, axial earth pressure, and pore water pressure of the deep soil are recorded respectively. The difference between the axial earth pressure and the pore water pressure is determined as the consolidation pressure of the deep soil. Based on the consolidation pressure and the lateral earth pressure, curves showing the variation of the deep earth lateral pressure coefficient with different depths and curves showing the variation of the deep earth lateral pressure coefficient with different consolidation pressures are obtained.

4. The method as described in claim 1, characterized in that, When the deep soil is clay, the expression for the curve of the deep soil lateral pressure coefficient as a function of depth and consolidation pressure is as follows: ； in, a, b, c These are dimensionless test parameters related to soil properties. γ The weight of soil. H To calculate the depth of the point, This refers to the consolidation pressure of clay acting on the clay. This represents the coefficient of deep soil lateral pressure in clay.

5. The method as described in claim 1, characterized in that, When the deep soil is sandy, the expression for the curve of the deep soil lateral pressure coefficient as a function of depth and consolidation pressure is as follows: ； in, The deep lateral earth pressure coefficient of sandy soil. a、b For dimensionless test parameters related to soil properties, γ The weight of soil. H To calculate the depth of the point, It is the pressure exerted on the sand by the consolidation pressure.

6. The method as described in claim 4 or 5, characterized in that, The formula for calculating the maximum horizontal ground pressure acting on the wellbore is: ； in, P H For calculation points H Horizontal ground pressure at that location H= , For the first i The natural unit weight of the soil layers. For the first i The thickness of the soil layer, K 0 For calculation points H The coefficient of deep soil lateral pressure at that location. n This represents the number of soil layers.

7. The method as described in claim 1, characterized in that, The formula for calculating the well wall thickness is: ； in, R The radius of the shaft excavation. The allowable compressive stress of the wellbore material. P max This represents the maximum horizontal ground pressure acting on the wellbore. d This refers to the well wall thickness.

8. The method as described in claim 1, characterized in that, The method further includes: Based on the calculation method of horizontal ground pressure in deep soil, combined with equilibrium conditions and Huke's law, the additional vertical stress on the well wall is obtained; Obtain the critical value of the deep soil layer thickness corresponding to the maximum vertical additional stress on the well wall; When the thickness of the deep soil layer exceeds a critical value, vertical instability is determined; vertical instability indicates well wall rupture. Vertical stability is determined when the thickness of the deep soil layer is less than or equal to the critical value of the deep soil layer thickness, and the vertical stability indicates that the well wall is safe.

9. A device for determining the wall thickness of a deep earthen well, characterized in that, include: The test module is used to conduct a high-pressure lateral pressure coefficient creep test on deep soil using a high-pressure lateral pressure coefficient consolidation apparatus to obtain curves showing the change of the deep soil lateral pressure coefficient with different depths and curves showing the change of the deep soil lateral pressure coefficient with different consolidation pressures; the high-pressure lateral pressure coefficient consolidation apparatus can control the deep soil to prevent lateral deformation. The fitting module is used to fit the curves of the deep soil lateral pressure coefficient with different depths and the curves of the deep soil lateral pressure coefficient with different consolidation pressures to obtain expressions for the curves of the deep soil lateral pressure coefficient with depth and consolidation pressure. The first determining module is used to apply the expression of the curve of the deep soil lateral pressure coefficient changing with depth and consolidation pressure to the calculation of the horizontal ground pressure value acting on the well wall, so as to obtain the maximum value of the horizontal ground pressure acting on the well wall. The second determining module is used to determine the minimum allowable well wall thickness based on the maximum value of the horizontal ground pressure acting on the well wall.

10. A computer-readable storage medium, characterized in that, The storage medium stores a computer program that, when executed by a processor, implements the method as described in any one of claims 1 to 8.

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