Method for evaluating influence of stored water of vertical shaft earth surface vertical crack on stability of well wall and supporting force

Abstract

The invention discloses a method for evaluating the influence of stored water of a vertical shaft earth surface vertical crack on the stability of a well wall and the supporting force, which comprises the following steps of: (1) determining the gravity of a damaged surrounding rock of the shaft according to the surrounding rock condition of the shaft, the position of the earth surface vertical crack and the like; (2) calculating water pressure according to the water accumulation and storage condition of the vertical crack; (3) the stability safety coefficient of the well wall is calculated, specifically, the sliding force and the anti-sliding force are calculated, and the corresponding stability safety coefficient is calculated; and (4) judging whether the well wall is safe or not, and if not, calculating the supporting force required for maintaining the stability of the well wall. The invention provides a quantitative evaluation method for the stability analysis of the underwater well wall of the earth surface vertical pull crack of the vertical shaft, and the stability safety coefficient of the well wall of the vertical shaft under different water collection and storage degrees and different pull crack depths of the earth surface pull crack can be evaluated through the method; and well wall supporting force can be analyzed and determined, so that reference is provided for vertical shaft supporting design, the problem of difficulty in stratum stability evaluation is solved, and countermeasures can be taken in advance.

Description

Technical Field

[0001] The invention belongs to the technical field of vertical shaft construction, and in particular relates to a method for evaluating the influence of water stored in vertical tensile cracks on the surface of a vertical shaft on the stability of the shaft wall and the supporting force. Background Art

[0002] In the construction of long and large tunnels, vertical shafts are often used to speed up the construction progress and facilitate operation and ventilation. For example, there are two construction shafts in the Gaoligongshan Tunnel of the Dali-Ruili Railway, and the ventilation shaft of the Huoshan Tunnel of the Yibin-Panzhihua Expressway. During the excavation of the shaft, due to the influence of excavation unloading, tension cracks often exist on the surface. Due to the influence of rainfall and other factors, water often accumulates in the tension cracks. The surface cracks and accumulated water will affect the safety and stability of the shaft. However, there are few literature reports on the influence of surface tension cracks and accumulated water on the stability of the shaft, especially the theoretical analysis of the stability of the shaft wall and the determination of the support force under the tension cracks and accumulated water. The stability of the shaft wall is the prerequisite for safe construction. How to judge whether the shaft is stable under the surface tension cracks is a concern of the construction unit, design unit, and especially the construction unit. Summary of the invention

[0003] The purpose of the present invention is to provide a method for evaluating the influence of water storage in vertical tensile cracks on the surface of a vertical shaft on the stability of the shaft wall and the supporting force in response to the above-mentioned technical problems existing in the prior art.

[0004] The above object of the present invention is achieved through the following technical solutions: The method for evaluating the influence of water storage in vertical tensile cracks on the surface of a shaft on the shaft wall stability and support force includes the following steps: (1) According to the surrounding rock conditions of the shaft, the location of the vertical tensile cracks on the ground, etc., the gravity of the surrounding rock destroyed by the shaft is determined and calculated as follows: ; In the formula, G To break the gravity of the surrounding rock for the shaft; is the weight of the surrounding rock of the shaft; L is the distance between the vertical tensile crack on the ground and the shaft; h is the depth of the vertical tensile cracks on the ground surface; is the fracture angle of the surrounding rock, which is calculated as follows: ; In the formula, is the internal friction angle of the surrounding rock; (2) Calculate the water pressure based on the water storage in the vertical cracks, which is calculated as follows: ; Where P W is the water pressure stored in the tension crack; is the internal friction angle of the surrounding rock; h W is the height of water storage in the tension crack; (3) Calculating the stability safety factor of the wellbore, which includes the following steps: (I) Calculate the sliding force according to the following formula: ; In the formula, is the sliding force; (II) Calculate the anti-slip force according to the following formula: ; In the formula, For anti-slip force; c is the cohesion of the surrounding rock; (III) Calculate the stability safety factor as follows: ; in, K is the stability safety factor of the wellbore; (4) Determine whether the wellbore is safe. If not, calculate the support force required to maintain the wellbore stability, which includes the following steps: (I) Compare the obtained stability safety factor with the allowable safety factor. If , then the shaft wall is safe; where [K] is the allowable stability safety factor; (II) If , then the well wall is unsafe and the well wall support force needs to be further determined, which is calculated as follows: ; in, P S The well wall support force.

[0005] The advantages of the present invention over existing research methods are as follows: the traditional vertical shaft stability analysis takes into account the surface tension cracks, especially the theoretical analysis of the influence of water accumulation in surface tension cracks on the stability of the vertical shaft is rare, and the existing literature mostly focuses on the case analysis of vertical shafts without surface cracks, and the methods adopted are mostly based on numerical simulation software for analysis.

[0006] The present invention provides a quantitative evaluation method for the stability analysis of a shaft under the condition that tensile cracks exist on the ground surface and there is water accumulation. The method can evaluate the safety factor of the shaft wall stability under different water accumulation degrees and different tensile crack depths of the surface tensile cracks; it can also analyze and determine the shaft wall support force, thereby providing a reference for the shaft support design, solving the problem of the difficulty in evaluating the stability of the formation, and facilitating the early adoption of countermeasures, such as strengthening the shaft wall support, pumping out the surface crack water, and adopting grouting reinforcement, thereby ensuring the safety of the shaft construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 The figure is a schematic diagram of the calculation of the method for evaluating the influence of water storage in vertical tensile cracks on the surface of a vertical shaft on the stability of the shaft wall and the supporting force of the present invention.

[0008] In the figure: 1 is the vertical shaft; 2 is the ground surface; 3 is the tension crack; 4 is the water stored in the tension crack; G To break the gravity of the surrounding rock for the shaft; is the weight of the surrounding rock of the shaft; L is the distance between the vertical tensile crack on the ground and the shaft; h is the depth of the vertical tensile cracks on the ground surface; is the fracture angle of the surrounding rock; P S is the wellbore support force; h W is the water storage height in the tension crack; P W It is the water pressure stored in the tension crack.

[0009] Figure 2 is the water storage height h of different cracks when the position of the surface tension crack remains unchanged W The shaft safety factor is . DETAILED DESCRIPTION

[0010] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0011] The specific data of this example project are as follows: The surrounding rock mass γ of a vertical shaft is 25kN / m 3 , surrounding rock cohesion c is 100kPa, the internal friction angle of surrounding rock is 23°, the distance L between the vertical tensile crack on the ground and the shaft is 6m, the depth of the vertical tensile crack on the ground is h=3m, and the height of the water in the crack is h W =2m, the weight of water is 10kN / m 3 , the allowable stability safety factor [K] is 1.2.

[0012] See also Figure 1 The method for evaluating the influence of water storage in vertical tensile cracks on the surface of a vertical shaft on the stability of the shaft wall and the supporting force is as follows: Step 1: According to the surrounding rock conditions of the shaft, the location of the vertical tensile cracks on the surface, etc., determine the gravity of the surrounding rock that the shaft destroys, which is calculated as follows: ; In the formula, G To break the gravity of the surrounding rock for the shaft; is the weight of the surrounding rock of the shaft; L is the distance between the vertical tensile crack on the ground and the shaft; h is the depth of the vertical tensile cracks on the ground surface; is the fracture angle of the surrounding rock, which is calculated as follows: ; In the formula, is the internal friction angle of the surrounding rock; Step 2: Calculate the water pressure according to the water storage in the vertical cracks. It is calculated as follows: ; Where P W is the water pressure stored in the tension crack; is the internal friction angle of the surrounding rock; h W is the height of water storage in the tension crack; Step 3: Calculate the stability safety factor of the wellbore, which includes the following steps: (I) Calculate the sliding force according to the following formula: ; In the formula, is the sliding force; (II) Calculate the anti-slip force according to the following formula: ; In the formula, For anti-slip force; c is the cohesion of the surrounding rock; (III) Calculate the stability safety factor as follows: ; in, K is the stability safety factor of the wellbore; Step 4: Determine whether the wellbore is safe. If not, calculate the support force required to maintain the wellbore stability, which includes the following steps: (I) Compare the obtained stability safety factor with the allowable safety factor. If , then the shaft wall is safe; where [K] is the allowable stability safety factor; (II) If , then the well wall is unsafe and the well wall support force needs to be further determined, which is calculated as follows: ; in, P S The well wall support force.

[0013] According to the above method and steps, the shaft stability safety factor K=1.41 can be obtained, which is greater than the allowable safety factor, and the shaft wall will not become unstable.

[0014] Furthermore, when other parameters remain unchanged, the water storage height h of different fractures is changed. W, the corresponding safety factor can be obtained Figure 2 , as the crack water storage height h W As the load increases, the safety factor K decreases.

Claims

1. A method for evaluating the influence of water storage in vertical tensile cracks on the surface of a vertical shaft on the stability of the shaft wall and its supporting force, characterized in that The steps include: (1) According to the surrounding rock conditions of the shaft, the location of the vertical tensile cracks on the ground, etc., the gravity of the surrounding rock destroyed by the shaft is determined and calculated as follows: ； In the formula, G To break the gravity of the surrounding rock for the shaft; is the weight of the surrounding rock of the shaft; L is the distance between the vertical tensile crack on the ground and the shaft; h is the depth of the vertical tensile cracks on the ground surface; is the fracture angle of the surrounding rock, which is calculated as follows: ； In the formula, is the internal friction angle of the surrounding rock; (2) Calculate the water pressure based on the water storage in the vertical cracks, which is calculated as follows: ； Where P W The water pressure in the tension cracks; is the internal friction angle of the surrounding rock; h W is the water storage height in the tension crack; (3) Calculating the stability safety factor of the wellbore, which includes the following steps: (I) Calculate the sliding force according to the following formula: ； In the formula, is the sliding force; (II) Calculate the anti-slip force according to the following formula: ； In the formula, For anti-slip force; c is the cohesion of the surrounding rock; (III) Calculate the stability safety factor as follows: ； in, K is the stability safety factor of the wellbore; (4) Determine whether the wellbore is safe. If not, calculate the support force required to maintain the wellbore stability, which includes the following steps: (I) Compare the obtained stability safety factor with the allowable safety factor. If , then the shaft wall is safe; where [K] is the allowable stability safety factor; (II) If , then the well wall is unsafe and the well wall support force needs to be further determined, which is calculated as follows: ； in, P S is the well wall support force; This can be used to evaluate the safety factor of shaft wall stability at different water storage levels and different depths of surface tensile cracks; it can also be used to analyze and determine the shaft wall support force.

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