Method for calculating surrounding rock pressure and influence range under instability of tunnel face of deep-buried tunnel

Abstract

The invention discloses a method for calculating surrounding rock pressure and influence range under instability of a deep tunnel face. The method mainly comprises the following steps: (1) determining a failure range angle in front of the face; (2) calculating the front damage width of the tunnel face; (3) calculating the damage height above the tunnel face; (4) calculating surrounding rock pressure; and (5) determining an influence range. The method is provided for calculating the surrounding rock pressure of the deeply-buried tunnel under the tunnel face instability and determining the influence range, then reference is provided for determining the corresponding supporting strength and supporting parameters, and design and construction units can conduct optimal design on supporting theoretically. The method disclosed by the invention can be applied to the pressure calculation of deep tunnels and underground engineering surrounding rocks with unstable tunnel faces, such as mining roadways, hydraulic tunnels, subways and the like, provides theoretical method reference for determining reasonable support parameter strength and support parameters, and is beneficial to the safety of tunnel construction.

Description

Technical Field

[0001] This invention relates to the field of tunnel design and construction, specifically to a method for calculating the surrounding rock pressure and influence range under instability at the tunnel face of a deep-buried tunnel. Background Technology

[0002] Landslides are a common accident in tunnels, as the saying goes, "nine out of ten tunnels will collapse during construction." As engineering projects expand into the deep sea, deep earth, and deep space, more and more tunnels and underground engineering projects are being built at great depths, especially mining tunnels and hydraulic tunnels for hydroelectric power generation. For example, the Jinping Hydropower Station's extra-long traffic tunnel, which also serves as an advanced exploration tunnel and construction auxiliary tunnel for the Jinping II Hydropower Station's water diversion tunnel, reaches a maximum depth of 2375 meters.

[0003] In cases of instability or collapse at the tunnel face of a deeply buried tunnel, the instability does not extend to the surface but typically occurs locally. However, the required support in this situation is stronger than when the tunnel face is stable. Determining the appropriate magnitude of surrounding rock pressure is a prerequisite for rational support design. However, current conventional calculations of surrounding rock pressure do not consider the situation of instability at the tunnel face of a deeply buried tunnel. Most existing literature studies the lateral surrounding rock pressure of deeply buried tunnels, rarely considering the situation of instability at the tunnel face, and rarely analyzing the scope of influence of such instability. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned technical problems in the prior art by providing a method for calculating the surrounding rock pressure and influence range under instability at the face of a deeply buried tunnel.

[0005] The above-mentioned objective of the present invention is achieved through the following technical solution: The method for calculating the surrounding rock pressure and influence range under the instability of the tunnel face in this deeply buried tunnel includes the following steps: (1) Determine the failure range angle in front of the working face, which is calculated using the following formula: ; in, β The angle of destruction in front of the palm; The internal friction angle of the surrounding rock at the tunnel face; (2) Calculate the failure width in front of the face of the tunnel face using the following formula: ; in, L AE The width of the destruction in front of the palm; D This refers to the excavation height at the working face; (3) Calculate the failure height above the tunnel face using the following formula: ; in,h The height of the damage above the working face; f The Protodextrin coefficient for the surrounding rock is determined by the following formula: ; (4) Calculate the surrounding rock pressure using the following formula: ; in, q γ represents the surrounding rock pressure; γ represents the unit weight of the surrounding rock. (5) Determine the scope of impact, which includes the following steps: (I) Calculate the influence range above the working face using the following formula: ; in, A 上 The area of ​​influence above the working face; (II) Calculate the area of ​​influence in front of the tunnel face using the following formula: ; in, A 前 The area of ​​influence in front of the palm striker.

[0006] The advantage of this invention compared to existing research methods is that, under conditions of instability or collapse at the tunnel face in deep-buried tunnels, the instability does not extend to the surface but typically occurs locally. However, the required support in this case is stronger than under stable conditions. Determining the appropriate magnitude of surrounding rock pressure is a prerequisite for rational support design. However, current conventional calculations of surrounding rock pressure do not consider the situation of instability at the tunnel face in deep-buried tunnels. Most existing literature studies the lateral surrounding rock pressure of tunnels, rarely considering the situation of tunnel face instability, and rarely analyzing the impact range of instability at the tunnel face in deep-buried tunnels.

[0007] This invention provides a method for calculating the surrounding rock pressure and determining the influence range of deep-buried tunnels under face instability, thereby providing a reference for determining the corresponding support strength and parameters. This is beneficial for design and construction units to theoretically optimize the support design. The method of this invention can be applied to the calculation of surrounding rock pressure in deep-buried tunnels and underground engineering projects with face instability, such as mining roadways, hydraulic tunnels, and subways. It also provides a theoretical method for determining reasonable support strength and parameters, which is beneficial to tunnel construction safety. Attached Figure Description

[0008] Figure 1 This is a schematic diagram illustrating the calculation method for the surrounding rock pressure and influence range under instability at the tunnel face in this invention.

[0009] Figure 1In the middle: 1 is the deep-buried tunnel; 2 is the tunnel face; 3 is the support lining; 4 is the area of ​​influence in front of the tunnel face; 5 is the area of ​​influence above the tunnel face. D This refers to the excavation height at the working face; β The angle of destruction in front of the palm; L This refers to the length of the unsupported section behind the working face; h The height of the damage above the working face. Detailed Implementation

[0010] The present invention will now be further described with reference to the accompanying drawings and embodiments.

[0011] The method of this invention is applied to an engineering example. Specific data for this example project are as follows: the unit weight γ of the surrounding rock in a deep-buried tunnel is 19 kN / m³. 3 internal friction angle of the surrounding rock at the working face The angle is 20°, and the excavation height at the working face is... D The length of the unsupported section behind the working face is 3m. L It is 2m.

[0012] See Figure 1 The method for calculating the surrounding rock pressure and influence range under instability at the tunnel face in this invention is as follows: Step 1: Determine the damage range angle in front of the tunnel face, which is calculated using the following formula: ; in, β The angle of destruction in front of the palm; The internal friction angle of the surrounding rock at the tunnel face; Step 2: Calculate the failure width in front of the tunnel face using the following formula: ; in, L AE The width of the destruction in front of the palm; D This refers to the excavation height at the working face; Step 3: Calculate the failure height above the working face using the following formula: ; in, h The height of the damage above the working face; f The Protodextrin coefficient for the surrounding rock is determined by the following formula: ; Step 4: Calculate the surrounding rock pressure using the following formula: ; in, q γ represents the surrounding rock pressure; γ represents the unit weight of the surrounding rock. Step 5: Determine the scope of impact, which includes the following steps: (I) Calculate the influence range above the working face using the following formula: ; in, A 上 The area of ​​influence above the working face; (II) Calculate the area of ​​influence in front of the tunnel face using the following formula: ; in, A 前 The area of ​​influence in front of the palm striker.

[0013] Based on the above method and steps, the surrounding rock pressure q under the instability of the tunnel face is obtained as 107.03 kPa.

[0014] Furthermore, determine the influence range A above the working face. 上 It is 15.40m 2 .

[0015] Furthermore, determine the area of ​​influence A in front of the face of the face. 前 It is 3.16m 2 .

[0016] Furthermore, under the condition of instability at the tunnel face, the support force provided by the lining must be greater than 107.03 kPa to be safe; the determined influence range in front of and above the tunnel face provides a reference for the scope of support reinforcement.

Claims

1. A method for calculating the surrounding rock pressure and influence range of a deep-buried tunnel face instability, characterized in that The method comprises the following steps: (1) determining the damage range angle in front of the working face, which is calculated according to the following formula: ； wherein, β is the angle of the failure zone in front of the face; is the internal friction angle of the surrounding rock of the face; (2) calculating the damage width in front of the working face, which is calculated according to the following formula: ； wherein, L AE is the width of the damage in front of the face; D is the height of the excavation of the face; (3) calculating the damage height above the working face, which is calculated according to the following formula: ； wherein h is the height of the failure above the face; f is the coefficient of the surrounding rock, which is determined by the following equation: ； (4) calculating the surrounding rock pressure, which is calculated according to the following formula: ； wherein, q Pw= pressure of the surrounding rock; γ = specific weight of the surrounding rock; (5) determining the influence range, which comprises the following steps: (I) calculating the influence range above the working face, which is calculated according to the following formula: ； wherein A 上 is the range of influence above the face (II) calculating the influence range in front of the working face, which is calculated according to the following formula: ； wherein A 前 is the influence range in front of the face.

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