Method for calculating critical applicable depth of sunken shaft

Abstract

The invention discloses a method for calculating the critical applicable depth of a sunken vertical shaft. The applicable depth of an existing sunken vertical shaft mostly depends on experience, the discreteness of the result is large, and the error between the result and the practical applicable depth is large. According to the method, the friction theory is taken as the reference, the test data is taken as the support, and the established quantitative parameterization calculation model can accurately express the critical applicable depth of the sunken shaft. The method adopted by the invention is based on theoretical calculation and test parameters, each parameter in calculation is clear in meaning and simple in application, a reference can be provided for calculation of the critical applicable depth of the sunken shaft under a complex stratum condition, a calculation result is high in reliability and repeatability, and the deviation between the calculation result and an engineering actual measurement result is small.

Description

TECHNICAL FIELD

[0002] The present application belongs to the technical field of predicting the critical applicable depth of a sunken shaft, and particularly relates to a method for calculating the critical applicable depth of a sunken shaft. BACKGROUND

[0003] When designing a sunken shaft, the critical applicable depth is an important index of the applicable range of the sunken shaft, which determines the applicable range of the shaft. Therefore, reasonably and accurately predicting the critical applicable depth of the sunken shaft and providing the corresponding applicable range are the focus of the current research on sunken shafts in the field of underground space.

[0004] The methods for researching the critical applicable depth of a sunken shaft generally include empirical methods, theoretical calculations, and numerical simulation analysis. The empirical method is greatly influenced by human factors and is subject to certain specific limiting conditions, including the properties of the stratum, the water content, the shaft diameter, and the adaptability of the construction method. Different engineers may obtain different values with large dispersion, and the method lacks reliability. The analysis method based on strict mathematical derivation can quantitatively consider the influence of geological parameters and structural geometric parameters after obtaining the relevant parameters of the stratum and structure, and is a practical method for predicting the critical applicable depth of a sunken shaft, which has strong repeatability. The numerical simulation analysis method can consider the coupling effects of stratum, structure, excavation construction, and other factors, but in the case of complex ground stress and uneven stratum conditions, the ideal state of the constitutive model will differ greatly from the actual situation, and the accuracy of the calculation results will deviate greatly from the actual situation.

[0005] Theoretical calculation method has been widely used in geotechnical engineering. Early research established a preliminary analysis framework for shaft load based on classical soil mechanics theory (such as Terzaghi's soil pressure theory and Rankine's theory). Some scholars modified the soil constitutive model (such as Mohr-Coulomb and Drucker-Prager models) and introduced the effect of groundwater seepage to derive analytical solutions under different stratum conditions. The critical applicable depth calculation formula for heterogeneous soil layers proposed by Hanna et al. (2014) reflects the actual working conditions through the soil strength reduction coefficient, significantly improving the applicability of the theoretical model. Numerical simulation methods (such as finite element method, discrete element method, and discrete element method) further reveal the nonlinear influence of stratum stiffness, support structure stiffness ratio, and construction disturbance on the critical applicable depth. Centrifuge model tests (Kim et al., 2018) verify the reliability of numerical simulation, confirming that the critical applicable depth is positively correlated with the shear strength of the soil, but may experience a sudden change under the action of seepage. The "shaft effect" theory proposed by Japanese scholars provides a mechanistic explanation for the sudden deformation of shafts in deep strata.

[0006] The existing critical application depth of sunken shaft has no specific calculation formula. The rise of intelligent prediction technology promotes the application of machine learning models (such as random forest and neural network), which can predict the error within 10% by inputting soil parameters, supporting parameters and environmental variables (Li et al., 2023). Based on the reliability theory (such as Monte Carlo simulation), the risk control standard is proposed with a failure probability of less than 5% as the design benchmark, and real-time monitoring technology (such as optical fiber sensing and BIM dynamic feedback) provides technical support for dynamic adjustment of critical depth. SUMMARY

[0007] In order to make up for the shortcomings of the prior art, the present application provides a calculation method for the critical application depth of a sunken shaft, which improves the calculation accuracy of the application depth of a sunken shaft by using geological parameters and structural physical quantities, and has higher reliability and higher operability.

[0008] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: A calculation method for the critical application depth of a sunken shaft, comprising the following steps: Step 1: Obtain the geological parameters of the surrounding rock of the sunken shaft through tunnel geological exploration; Step 2: Obtain the friction coefficient COF between the structure of the sunken shaft and the surrounding stratum through structural test and theoretical calculation of the surrounding soil layer of the sunken shaft; Step 3: Calculate the self-weight of the structure within the calculation range of the sunken shaft G and additional force G 1; Step 4: Calculate the structural force f ( H ); Step 5: Calculate the critical application depth of the sunken shaft according to the data calculated in steps 1-4 H cr .

[0009] Further, in step 4, the calculation method of the structural force f ( H ) is as follows: wherein, H is the depth of the sunken shaft, λ is the active soil lateral pressure coefficient, L is the perimeter of the contact surface between the sunken shaft and the surrounding soil, H 0 is the load calculation depth of the active soil lateral pressure around the sunken shaft.

[0010] Further, in step 4, the load calculation depth HThe calculation method is as follows: H 0= k r × (2.0~2.5)D Wherein k r is the stable pressure adjustment coefficient of soil layer, and D is the excavation diameter or equivalent excavation diameter of the sunken shaft.

[0011] Further, in the step four, the active soil lateral pressure coefficient λ The calculation method is as follows: Wherein, is calculated by the internal friction angle, and σ is the horizontal stress of rock stratum.

[0012] Further, in the step five, when the stratum is a single soil layer, the critical applicable depth of the sunken shaft H cr The calculation method is as follows: Firstly, calculate F 1: In the formula, F 1 is the friction resistance of the sunken shaft in the depth range of the soil layer under the ground surface; H 0; If F 1≥[ G + G 1]1, it is determined that the critical applicable depth of the sunken shaft H cr In the load calculation demarcation depth H 0, the critical applicable depth is directly calculated according to the following formula in the stratum range of the depth: Wherein the critical applicable depth H cr is the integral limit, and G + G 1]1 is the friction resistance of the sunken shaft in the depth range of the soil layer under the ground surface; H cr is the sum of the self weight of the sunken shaft structure and the additional force of the sunken shaft structure in the depth position to the ground surface.

[0013] If F 1<[ G + G 1]1, it is determined that the critical applicable depth of the sunken shaft H cr Not in the load calculation demarcation depth H 0, the load calculation demarcation depth H0 is the demarcation point to calculate the friction resistance of the sunken shaft: Load calculation demarcation depth below: The critical applicable depth calculation formula of the sunken shaft is obtained as: F 1+ F 2=[ G + G 1] Hcr Wherein F 2 is the soil H 0 to H cr The friction resistance of the sunken shaft in the range of G + G 1] Hcr The critical applicable depth of the sunken shaft is the sum of the self-weight of the sunken shaft structure and the additional force of the sunken shaft structure in the range of the ground surface.

[0014] Further, in step five, when the stratum is a non-single soil layer, the critical applicable depth of the sunken shaft H cr The calculation method is as follows: The friction resistance of the sunken shaft in the range of the first layer of soil under the ground surface is: When F 1≤[ G + G 1]1, continue to calculate the second layer of soil, and the friction resistance of the sunken shaft in the range of the second layer of soil under the ground surface is: When F 1+ F 2≤[ G + G 1]2, continue to calculate the third layer of soil; In turn, …… The friction resistance of the sunken shaft in the range of the n layer of soil under the ground surface is: When F 1+ F 2+…+ F n ≥[ G + G 1] n , it means that the critical calculation depth is in the range of the n layer of soil, and the critical applicable depth of the sunken shaft H cr The calculation formula is: wherein the critical applicable depth H cr is the integral limit, H 1、 H 2, …, H n is the distance from the bottom surface of the 1st, 2nd, …, nth layer of soil to the ground surface, F 1、 F 2, …, F n is the frictional resistance received by the sunken shaft within the range of the 1st, 2nd, …, nth layer of soil, G + G 1], G + G 2, …, G + G 1] n is the sum of the self-weight of the sunken shaft structure and the additional force of the sunken shaft structure within the range from the bottom surface of the 1st, 2nd, …, nth layer of soil to the ground surface, G + G 1] Hcr is the sum of the self-weight of the sunken shaft structure and the additional force of the sunken shaft structure within the range from the critical applicable depth of the sunken shaft to the ground surface; wherein, F n The calculation method is as follows: Firstly F n Without layering calculation: If the obtained H cr > H 0, the load calculation dividing depth H 0 is taken as the dividing point for F n Layering calculation: Finally, the critical applicable depth H cr is calculated through the critical applicable depth calculation formula.

[0015] Further, in the step three, the structure additional force G 1 calculation method is as follows: G 1= G 11 + G 12 + G 13 Wherein G 11 The dead weight generated by the additional components on the sunken shaft structure, G 12 The dead weight generated by the equipment and machinery on the sunken shaft structure, G 13 The dead weight generated on the sunken shaft due to other factors.

[0016] Further, in the step three, the dead weight of the sunken shaft structure G The calculation method is as follows: G = γ 结构 × V Wherein, γ 结构 is the container weight, V is the volume of the structure.

[0017] The beneficial effects of the present application are: 1) The present application provides a practical calculation formula by bringing the data obtained from the test into the calculation formula to predict the temporary applicable depth of the sunken shaft, the meaning of each parameter in the formula is more clear, the operation and application are simple, and it can provide a reference for predicting the critical applicable buried depth of the sunken shaft under complex stratum conditions; 2) Compared with the numerical simulation calculation method, the result calculated by the formula of the present application is closer to the actual situation and more reasonable when calculating the temporary applicable depth of the sunken shaft; 3) The present application is based on engineering test data and establishes a model based on the theory of friction coefficient, which can accurately describe the critical applicable buried depth of the sunken shaft, has strong engineering applicability, high structure calculation reliability, and great significance for guiding practical engineering. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is the operation flowchart of the present application; Figure 2 is the critical applicable depth calculation model of a single stratum of a sunken shaft in Wenzhou of the present application; Figure 3 is the critical applicable depth calculation model of a complex stratum in a certain city of Jiangsu of the present application; Figure 4 is the critical applicable depth of the stratum when different additional loads are applied on the basis of the second embodiment of the present application. DETAILED DESCRIPTION

[0019] The present application will be described in detail below in combination with specific embodiments.

[0020] The application establishes a parameterized sinking shaft model, and deduces a critical applicable depth prediction method based on the sinking shaft according to the friction coefficient theory, so as to provide a reference for the applicable conditions of the sinking shaft structure under complex stratum conditions.

[0021] As Figure 1 shown, the calculation method of the critical applicable depth of the sinking shaft is applicable to soil or rock stratum, and specifically includes the following steps: Step one: obtaining the surrounding rock geological parameters of the sinking shaft through tunnel geological exploration; Step two: obtaining the friction coefficient COF of the sinking shaft structure and the surrounding stratum through the structure test and theoretical calculation of the surrounding soil layer of the sinking shaft; Step three: calculating the structure self-weight G and additional force G 1 in the calculation range of the sinking shaft, specifically as follows: 1) additional force of the sinking shaft structure in the calculation range G 1 calculation method is as follows: G 1= G 11 + G 12 + G 13 Wherein G 11 is the dead weight generated by the additional components on the sinking shaft structure, G 12 is the dead weight generated by the equipment and machinery on the sinking shaft structure, G 13 is the dead weight generated on the sinking shaft due to other factors; 2) structure self-weight of the sinking shaft G Calculation method is as follows: G = γ 结构 × V Wherein, γ 结构 is the unit weight, V is the volume of the structure.

[0022] Step four: calculating the structure acting force f ( H ), the calculation method is as follows: Wherein, H is the depth of the sinking shaft, λ is the active soil lateral pressure coefficient, L is the circumference of the contact surface between the outside of the shaft and the surrounding soil.H 0 is the load calculation demarcation depth of the active soil lateral pressure of the sunken shaft periphery; Load calculation demarcation depth H 0 is calculated as follows: H 0= k r × (2.0~2.5)D Wherein k r D is the excavation diameter or equivalent excavation diameter of the sunken shaft; Active soil lateral pressure coefficient λ The calculation method is as follows: Wherein, is the calculation of internal friction angle, σ is the horizontal stress of rock stratum.

[0023] Step five: according to the data calculated in steps one to four, the critical applicable depth of the sunken shaft is calculated H cr , as follows: 1) when the stratum is single soil layer, the critical applicable depth of the sunken shaft H cr The calculation method is as follows: First calculate F 1: In the formula, F 1 is the friction resistance of the sunken shaft in the depth range of the soil under the ground surface H 0; If F 1≥[ G + G 1]1, it is determined that the critical applicable depth of the sunken shaft H cr In the stratum range of the load calculation demarcation depth H 0, the critical applicable depth is directly calculated as follows: Wherein the critical applicable depth H cr is the integral limit, G + G 1]1 is the sum of the self weight of the sunken shaft structure and the additional force of the sunken shaft structure in the range from the depth position of the soil under the ground surface to the ground surface. H cr

[0024] If F 1<[ G +​G 1]1, Determining the critical applicable depth of sunken shafts H cr Not at the load calculation boundary depth H Within the range of 0, the boundary depth needs to be calculated based on the load. H Calculate the frictional resistance of the sunken shaft using 0 as the dividing point: Below the load calculation boundary depth: The formula for calculating the critical applicable depth of a sunken shaft is as follows: F 1+ F 2=[ G + G 1] Hcr in F 2 represents subsurface soil H 0 to H cr The frictional resistance experienced by the sunken shaft within the range, G + G 1] Hcr It is the sum of the self-weight of the sunken shaft structure and the additional forces acting on the sunken shaft structure within the critical applicable depth to the ground surface.

[0025] 2) When the stratum is not a single soil layer, the critical applicable depth of the sunken shaft. H cr The calculation method is as follows: Frictional resistance experienced by the sunken shaft within the first layer of soil below the surface: when F 1≤[ G + G At point 1, the calculation continues downwards to the second soil layer. The frictional resistance experienced by the sunken shaft within the area of ​​the second soil layer below the surface is: when F 1+ F 2≤[ G + G When 1]2, continue calculating the third layer of soil downwards; Calculate in sequence... The frictional resistance experienced by a sunken shaft within the nth layer of soil (rock) below the surface: when F 1+ F 2+…+ F n ≥[ G +G 1] n When the critical calculation depth is within the nth soil layer, the critical applicable depth of the sunken shaft is obtained. H cr The calculation formula is: Among them, the critical applicable depth For integration limits, H 1. H 2、…、 H n These represent the distances from the bottom surface of the 1st, 2nd, ..., nth soil layers below the surface to the surface. F 1. F 2、…、 F n These represent the frictional resistance experienced by the sunken shaft within the 1st, 2nd, ..., nth soil layers below the surface. G + G 1]1、[ G + G 1]2、…、[ G + G 1] n These are the sum of the self-weight of the sunken shaft structure and the additional forces acting on the sunken shaft structure within the range from the bottom surface of the 1st, 2nd, ..., nth soil layers below the ground surface to the ground surface. G + G 1] Hcr It is the sum of the self-weight of the sunken shaft structure and the additional forces acting on the sunken shaft structure within the critical applicable depth to the ground surface. in, F n The calculation method is as follows: first F n No stratified calculation: If the result is... H cr > H If the value is 0, then the boundary depth is calculated based on the load. For the dividing point pair F n Perform stratified calculations: Finally, the critical applicable depth calculation formula was used to obtain... H cr .

[0026] The specific implementation method is as follows: 1) Example 1 Taking a sunken vertical shaft parking lot in Wenzhou City as an example, such as...Figure 2 As shown, the sunken shaft is basically level on the ground surface, with an inner diameter of 23m and a wall thickness of 0.7m. After surface leveling, the strata are mainly bedrock, with a weakly weathered layer exceeding 100m in thickness. When calculating the critical applicable depth of the sunken shaft using the method of this invention, external additional forces are not considered in the calculation, and a value of... G 1=0 KN The calculation process is as follows: Step 1: Geological surveys revealed the following geological parameters of the surrounding rock of the sunken shaft: stratum unit weight γ = 24 kN / m³ 3 The active side pressure coefficient λ = 0.2.

[0027] Step Two: The friction coefficient (COF) between the sunken shaft structure and the surrounding strata was found to be 0.1 through experiments.

[0028] Step 3: The self-weight of the sunken shaft structure is calculated as follows: The calculation no longer considers the additional forces of the sunken shaft structure, i.e., takes G 1 = 0.

[0029] Step 4: Calculate the structural forces using theoretical calculation methods: Load boundary depth H 0 is calculated as follows: Pick k r =1.0, rock strata are usually taken as H 0 = 1.0 × 2.0 × D = 1.0 × 2.0 × 24.2 = 48.4 m ①Depth range of 0m-48.4m: f ( H ) = 24 × H ×0.2×0.1×π×24.2=36.5 H ②Below a depth of 48.4m: f ( H = 24 × 48.4 × 0.2 × 0.1 × π × 24.2 = 1766.2 Step 5: 42743.2 < 1303.0 × 48.4 = 63065.2, the critical applicable depth for sunken shafts. H cr It is not within the 48.4m depth stratum range.

[0030] Below a depth of 48.4m: Substitute into the critical applicable depth formula: Solve for the critical applicable depth of the sunken shaft. H cr =92.3 m >48.4 m .

[0031] 2) Example 2 Taking a municipal drainage pumping station project in Jiangsu Province as an example, such as... Figure 3 As shown, the sunken shaft is located on flat urban ground, with an inner diameter of 8m and a wall thickness of 0.5m. The first 2m below the surface is a fill layer; the second layer below the surface is silty clay, 10m thick; and the third layer below the surface is clay, exceeding 30m in thickness. When calculating the critical applicable depth of the sunken shaft using the method of this invention, external additional forces are not considered, and a value of... G 1=0 KN The calculation process is as follows: Step 1: Geological parameters of the surrounding rock around the sunken shaft were obtained through geological exploration: Surface soil layer: unit weight γ = 18 kN / m 3 Cohesion c = 10 kPa, internal friction angle φ = 20°; Second soil layer: Unit weight γ = 19kN / m 3 Cohesion c = 20 kPa, internal friction angle φ = 25°; Third soil layer: Unit weight γ = 20kN / m 3 The cohesion c = 30 kPa and the internal friction angle φ = 29°.

[0032] Step Two: The friction coefficient between the sunken shaft structure and the surrounding strata was obtained through experiments. Surface soil layer: The coefficient of friction COF obtained from the test is 0.05; Second soil layer: The friction coefficient COF obtained from the test is 0.07; The third soil layer: the friction coefficient COF obtained from the test is 0.10.

[0033] Step 3: The self-weight of the sunken shaft structure is calculated as follows: The calculation no longer considers the additional forces of the sunken shaft structure, i.e., takes G 1 = 0.

[0034] Step 4: Calculate the structural forces using theoretical calculation methods. Load boundary depth H 0 is calculated as follows: Pick k r =1.0, soil strata are usually taken as H 0 = 1.0 × 2.5 × D = 1.0 × 2.5 × 9 = 22.5 m ① Calculation of the first soil layer f ( H ) = 18 × H ×0.490×0.05×π×9=12.5 H ② Second layer of soil f ( H )=[18×2+19×( H -2)]×0.406×0.10×π×9=21.8× H - 2.3 ③ Third layer of soil Depth range of 12m-22.5m: f ( H ) = [18×2+19×10+20×10.5+20×( H -22.5)]×0.347×0.10×π×9=19.6 H -13.7 Below 22.5m: f ( H = [18×2+19×10+20×(22.5-12)]×0.347×0.10×π×9=427.8 Step 5: 25.0 < 333.8 × 2 = 667.6, therefore the critical burial depth is not within the first soil layer. 25.0 + 1503.0 = 1528.0 < 333.8 × 12 = 4005.6, the critical burial depth is not within the range of the second soil layer. Substitute into the critical applicable depth formula: Solving H cr =34.6 m >22.5 m， This indicates that the critical applicable depth is greater than the load boundary depth, and calculations need to be performed separately according to the load boundary depth range.

[0035] ①Depth range of 12m-22.5m ②Below 22.5m depth Substitute into the critical applicable depth formula: 1528.0 + 3406.2 + 427.8 × ( H cr -22.5) = 333.8 × H cr Solve for the critical applicable depth of the sunken shaft. H cr =49.9 m >22.5 m。

[0036] Example 3: Based on Example 2, under different additional loads, the calculation steps of Example 2 were repeated, and the critical applicable depth of the sunken shaft obtained by applying the method of the present invention was as follows: Figure 4 As shown, in practical engineering applications, additional forces can be applied to the sunken shaft. The greater the additional force, the deeper the critical applicable depth of the sunken shaft.

[0037] The content of this invention is not limited to the embodiments listed. Any equivalent modifications made by those skilled in the art to the technical solutions of this invention by reading this specification are covered by the claims of this invention.

Claims

1. A method for calculating the critical applicable depth of a sunken vertical shaft, characterized in that: Includes the following steps: Step 1: Obtain the geological parameters of the surrounding rock of the sunken shaft through tunnel geological exploration; Step 2: Through structural tests and theoretical calculations of the soil layers surrounding the sunken shaft, the coefficient of friction (COF) between the sunken shaft structure and the surrounding soil layers is obtained; Step 3: Calculate the self-weight of the structure within the calculation range of the sunken shaft. G and additional forces G 1; Step 4: Calculate structural forces f ( H ); Step 5: Based on the data obtained in Steps 1-4, calculate the critical applicable depth of the sunken shaft. H cr .

2. The method for calculating the critical applicable depth of a sunken vertical shaft according to claim 1, characterized in that: In step four, structural forces f ( H The calculation method is as follows: in, H The depth of the sunken shaft. λ The active earth lateral pressure coefficient, L This is the perimeter of the contact surface between the outer side of the shaft and the surrounding soil. H 0 represents the load calculation boundary depth for the active earth lateral pressure around the sunken shaft.

3. The method for calculating the critical applicable depth of a sunken vertical shaft according to claim 2, characterized in that: In step four, the load calculation boundary depth H The calculation method for 0 is as follows: H 0= k r ×（2.0~2.5）D in k r is the soil stability pressure adjustment coefficient, and D is the excavation diameter or equivalent excavation diameter of the sunken shaft.

4. The method for calculating the critical applicable depth of a sunken vertical shaft according to claim 3, characterized in that: In step four, the active earth pressure coefficient λ The calculation method is as follows: in, To calculate the internal friction angle, σ is the horizontal stress in the rock formation.

5. The method for calculating the critical applicable depth of a sunken vertical shaft according to claim 4, characterized in that: In step five, when the stratum is a single soil layer, the critical applicable depth of the sunken shaft is... H cr The calculation method is as follows: First calculate F 1: In the formula, F 1 represents subsurface soil H Frictional resistance experienced by a sunken vertical shaft within a depth range of 0; If you get F 1≥[ G + G 1]1, Determining the critical applicable depth of sunken shafts H cr At the load calculation boundary depth H Within the 0-depth stratum range, the critical applicable depth is directly calculated using the following formula: Among them, the critical applicable depth H cr For the integration limit, [ G + G 1]1 represents subsurface soil H cr The sum of the self-weight of the sunken shaft structure and the additional forces acting on the sunken shaft structure within the depth range from the ground surface; If you get F 1 < [ G + G 1]1, Determining the critical applicable depth of sunken shafts H cr Not at the load calculation boundary depth H Within the range of 0, the boundary depth needs to be calculated based on the load. H Calculate the frictional resistance of the sunken shaft using 0 as the dividing point: Below the load calculation boundary depth: The formula for calculating the critical applicable depth of a sunken shaft is as follows: F 1+ F 2=[ G + G 1] Hcr in F 2 represents subsurface soil H 0 to H cr The frictional resistance experienced by the sunken shaft within the range, G + G 1] Hcr It is the sum of the self-weight of the sunken shaft structure and the additional forces acting on the sunken shaft structure within the critical applicable depth to the ground surface.

6. The method for calculating the critical applicable depth of a sunken vertical shaft according to claim 5, characterized in that: In step five, when the stratum is not a single soil layer, the critical applicable depth of the sunken shaft is... H cr The calculation method is as follows: Frictional resistance experienced by the sunken shaft within the first layer of soil below the surface: when F 1≤[ G + G At point 1, the calculation continues downwards to the second soil layer. The frictional resistance experienced by the sunken shaft within the area of ​​the second soil layer below the surface is: when F 1+ F 2≤[ G + G When 1]2, continue calculating the third layer of soil downwards; Calculate in sequence... The frictional resistance experienced by the sunken shaft within the nth layer of soil below the surface: when F 1+ F 2+…+ F n ≥[ G + G 1] n When the critical calculation depth is within the nth soil layer, the critical applicable depth of the sunken shaft is obtained. H cr The calculation formula is: Among them, the critical applicable depth H cr For integration limits, H 1. H 2、…、 H n These represent the distances from the bottom surface of the 1st, 2nd, ..., nth soil layers below the surface to the surface. F 1. F 2、…、 F n These represent the frictional resistance experienced by the sunken shaft within the 1st, 2nd, ..., nth soil layers below the surface. G + G 1]1、[ G + G 1]2、…、[ G + G 1] n These are the sum of the self-weight of the sunken shaft structure and the additional forces acting on the sunken shaft structure within the range from the bottom surface of the 1st, 2nd, ..., nth soil layers below the ground surface to the ground surface. G + G 1] Hcr It is the sum of the self-weight of the sunken shaft structure and the additional forces acting on the sunken shaft structure within the critical applicable depth to the ground surface. in, F n The calculation method is as follows: first F n No stratified calculation: If the result is... H cr > H If the value is 0, then the boundary depth is calculated based on the load. H 0 is the dividing point pair F n Perform stratified calculations: Finally, the critical applicable depth calculation formula was used to obtain... H cr .

7. A method for calculating the critical applicable depth of a sunken vertical shaft according to claim 6, characterized in that: In step three, the additional structural forces within the calculation range of the sunken shaft are... G The calculation method is as follows: G 1= G 11 + G 12 + G 13 in G 11 The additional weight generated by the additional components on the sunken shaft structure. G 12 The weight-bearing capacity generated by equipment and machinery on the sunken shaft structure. G 13 Other factors contribute to the weight distribution on the sunken shaft.

8. The method for calculating the critical applicable depth of a sunken vertical shaft according to claim 7, characterized in that: In step three, the self-weight of the sunken shaft structure G The calculation method is as follows: G = c 结构 × V Where, γ 结构 For density, V Let be the volume of the structure.

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