Method for calculating mud pressure support efficiency at shield excavation face
By calculating the dissipation slope of the ultra-static pore water pressure in front of the mud-water shield excavation face and the friction angle in the formation, the effective support range of mud-pressure is determined, and the problem of calculating mud-support efficiency in the existing technology is solved, achieving safe and efficient construction and economic cost reduction effects.
Patent Information
- Application Number
- CN202411359546.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-27
- Publication Date
- 2025-03-11
AI Technical Summary
The existing technology lacks simple and efficient theoretical methods to calculate the mud support efficiency during the excavation process of mud-water shield, which makes it difficult to ensure the stability of the excavation surface.
By calculating the dissipation slope of the ultra-static pore water pressure in front of the excavation face and the internal friction angle parameters of the excavation formation, the total range of mud pressure support and the potential sliding area range are determined, and the overlapping area is taken as the effective support range of mud pressure, thereby calculating the support efficiency of mud pressure.
It realizes the rapid and simple calculation of the support efficiency of mud pressure while ensuring the safe and efficient construction of mud and water shield structures, reduces mud waste and reduces construction economic costs.
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Figure CN119598549A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of slurry shield, and in particular to a method for calculating the slurry pressure support efficiency at a shield excavation face. Background Art
[0002] In recent years, the progress of infrastructure construction in my country has been accelerating, and the construction of underground projects such as highway tunnels, railway tunnels, hydraulic tunnels and municipal pipe corridors is in a period of rapid development. The shield method has been increasingly widely used in tunnel engineering construction at home and abroad due to its advantages of safety and efficiency. Slurry shield has been widely used in the construction of underwater tunnel projects due to its unique excavation face support mode. The working principle of slurry shield is to stabilize the tunnel excavation face by pressurized mud for excavation construction. Therefore, excavation face stability is a very important aspect of slurry shield construction. In order to ensure the stability of the excavation face, the mud pressure should be able to be quickly and efficiently converted into effective stress of the soil during construction. The longer the mud pressure is transmitted forward, the longer the distance of excess pore water pressure dissipation, the lower the mud support efficiency, and the more unfavorable the excavation face stability. Therefore, studying the mud pressure support efficiency during slurry shield excavation is of great significance to the stability of the excavation face.
[0003] At present, the mud support efficiency is mainly calculated by monitoring data of fixed pore water pressure points. The calculation of mud support efficiency relies heavily on the layout of monitoring points, but it is difficult for monitoring points to cover the entire route of shield tunneling. Therefore, the existing excavation face stability theory system lacks a simple and efficient theoretical method to calculate the mud support efficiency during slurry shield tunneling. Summary of the invention
[0004] The present invention provides a method for calculating the support efficiency of mud pressure at a shield excavation face. The support efficiency of mud pressure can be simply and quickly calculated according to the dissipation slope of excess pore water pressure in front of the excavation face and the internal friction angle parameters of the excavated stratum. Thus, under the premise of ensuring the safe and efficient construction of the slurry shield, the waste of mud can be reduced and the economic cost of construction can be reduced.
[0005] The present invention is achieved through the following technical solutions: A method for calculating the slurry pressure support efficiency at a shield excavation face comprises the following steps: S01. Calculate the dissipation distance of the excess pore water pressure at the top and bottom of the slurry shield excavation surface according to the dissipation slope of the excess pore water pressure in front of the slurry shield excavation surface, and determine the total range of the slurry pressure support; S02, according to the internal friction angle of the stratum excavated by the slurry shield Determine the extent of the potential sliding area ahead of the excavation face; S03. The overlapping area between the total mud pressure support range and the potential sliding area range is taken as the effective mud pressure support range; S04. The calculation formula for mud pressure support efficiency at the excavation face is: Where: is the mud pressure support efficiency at the excavation face, is the total area of mud pressure support, It is the area of effective support range of mud pressure.
[0006] Furthermore, in step S01, the steps for calculating the dissipation distance of the excess pore water pressure at the top and bottom of the excavation face of the slurry shield are as follows: S0101. Convert the pore pressure-time relationship curve collected by the pore water pressure meter during the test into the pore pressure-distance relationship curve at different times and locations; S0102. Compare the change in pore water pressure on the pore pressure-distance relationship curve and its corresponding dissipation distance to obtain a dissipation slope; S0103. According to the geological characteristics of the slurry shield tunneling, the excess pore water pressure at the top and bottom cutouts of the slurry shield is calculated by using the water-soil combined calculation method or the water-soil separate calculation method. The dissipation distance of the excess pore water pressure at the top and bottom of the slurry shield excavation face is calculated based on the determined dissipation slope.
[0007] Furthermore, in step S02, the internal friction angle of the stratum excavated by the slurry shield is determined by indoor triaxial compression test, direct shear test method, or obtained by static penetration test on site.
[0008] Further, in step S01, a plane coordinate system is established with the bottom of the slurry shield excavation surface as the origin, with the forward direction of the excavation surface as the positive direction of the X axis, and with the vertical upward direction of the excavated stratum as the positive direction of the Y axis; Take point A on the X-axis, point A is the dissipation distance of the excess pore water pressure at the bottom of the shield excavation surface, take point B on the plane coordinate system, the distance of point B on the Y-axis is the distance between the top and the bottom of the slurry shield excavation surface, and the distance of point B on the X-axis is the dissipation distance of the excess pore water pressure at the top of the shield excavation surface; A trapezoidal area is drawn on the plane coordinate system according to point A and point B, and the trapezoidal area is the total range of mud pressure support.
[0009] Further, in step S02, Take point C on the plane coordinate system. The distance of point C on the Y axis is the distance between the top and the bottom of the slurry shield excavation surface. The angle between the line formed by point C and the origin and the Y axis is 45°+ , A triangular area is drawn on the plane coordinate system according to the origin and point C. The triangular area and the square area directly above reaching the surface together form a wedge-shaped area, and the wedge-shaped area is the range of the potential sliding area; The line formed by point C and the origin divides the trapezoidal area into two areas. The area located obliquely below is the invalid range of mud pressure support.
[0010] Further, in step S04, The area of the total range of mud pressure support is determined by the trapezoidal area calculation method, and the area of the effective mud pressure support range is determined by the area of the total range of mud pressure support minus the area of the invalid range of mud pressure support. The invalid range of mud pressure support is a triangle, and the invalid support range is determined by the triangle area calculation method.
[0011] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention can simply and quickly calculate the support efficiency of the mud pressure according to the dissipation slope of the excess pore water pressure in front of the excavation face and the internal friction angle parameter of the excavated stratum, thereby reducing the waste of mud and reducing the economic cost of construction while ensuring the safe and efficient construction of the slurry shield; 2. Draw the total range of mud pressure support and the potential sliding area on the plane coordinate system, and take the overlapping area of the total range of mud pressure support and the potential sliding area as the effective support range of mud pressure. The support efficiency of mud pressure can be simply and quickly calculated through the area ratio of the effective support range of mud pressure to the total range of mud pressure support; 3. The area of the effective mud pressure support range is determined by subtracting the area of the invalid mud pressure support range from the area of the total mud pressure support range. The invalid mud pressure support range is a triangle, and the invalid support range is determined by calculating the triangle area, which makes the calculation method simpler. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Figure 1 This is a calculation flow chart of the method for calculating the mud pressure support efficiency at the shield excavation face described in this embodiment; Figure 2 It is a schematic diagram of the potential sliding area range and the total range of mud pressure support in the plane coordinate system described in this embodiment; Figure 3 is a schematic diagram showing that the invalid range of mud pressure support in the plane coordinate system described in this embodiment is a triangle; Figure 4 is a schematic diagram showing that the effective range of mud pressure support in the plane coordinate system described in this embodiment is a triangle; In the figure: 1. Range of potential sliding area, 2. Total range of mud pressure support, 3. Ineffective range of mud pressure support, 4. Effective range of mud pressure support. DETAILED DESCRIPTION
[0013] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0014] In the description of the invention, it should be understood that the terms "front", "rear", "upper", "lower", "left", "right" and the like indicate directions or positional relationships based on directions or positional relationships shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the invention. The invention is further described below in conjunction with the drawings and embodiments.
[0015] This embodiment proposes a method for calculating the mud pressure support efficiency at the shield excavation face. The calculation flow chart is as follows: Figure 1 As shown, the following steps are included: S01. Calculate the dissipation distance of the excess pore water pressure at the top and bottom of the slurry shield excavation surface according to the dissipation slope of the excess pore water pressure in front of the slurry shield excavation surface, and determine the total range of the slurry pressure support; In this step, the calculation steps for the dissipation distance of the excess pore water pressure at the top and bottom of the slurry shield excavation face are as follows: S0101. Convert the pore pressure-time relationship curve collected by the pore water pressure meter during the test into the pore pressure-distance relationship curve at different times and locations; S0102. Compare the change in pore water pressure on the pore pressure-distance relationship curve and its corresponding dissipation distance to obtain a dissipation slope. Since this calculation is a conventional technical means, it will not be described in detail here; S0103. According to the stratum characteristics of the slurry shield tunneling, the excess pore water pressure at the top and bottom cutouts of the slurry shield is calculated by using the water-soil calculation method or the water-soil calculation method. According to the determined dissipation slope, the dissipation distance of the excess pore water pressure at the top and bottom of the slurry shield excavation surface is calculated respectively. Since this calculation is a conventional technical means, it is not described in detail here. A plane coordinate system is established with the bottom of the slurry shield excavation surface as the origin, the forward direction of the excavation surface as the positive direction of the X axis, and the vertical upward direction of the excavated stratum as the positive direction of the Y axis; Take point A on the X-axis, point A is the dissipation distance of the excess pore water pressure at the bottom of the shield excavation surface, take point B on the plane coordinate system, the distance of point B on the Y-axis is the distance between the top and the bottom of the slurry shield excavation surface, and the distance of point B on the X-axis is the dissipation distance of the excess pore water pressure at the top of the shield excavation surface; A trapezoidal area is drawn on the plane coordinate system according to point A and point B. The trapezoidal area is the total range 2 of mud pressure support, and the dissipation distance at the top is smaller than the dissipation distance at the bottom. S02, according to the internal friction angle of the stratum excavated by the slurry shield Determine the potential sliding area in front of the excavation face1; In this step, the internal friction angle of the stratum excavated by the slurry shield is determined by indoor triaxial compression test and direct shear test, or obtained by static penetration test on site; like Figure 2 As shown, point C is taken on the plane coordinate system. The distance of point C on the Y axis is the distance between the top and the bottom of the slurry shield excavation surface. The angle between the line formed by point C and the origin and the Y axis is 45°+ , A triangular area is drawn on the plane coordinate system according to the origin and point C. The triangular area and the square area directly above the ground surface together form a wedge-shaped area, which is the potential sliding area range 1; The line formed by point C and the origin divides the trapezoidal area into two areas. The area located at the lower side is the invalid range of mud pressure support. S03, taking the overlapping area of the total mud pressure support range 2 and the potential sliding area range 1 as the mud pressure effective support range 4; S04. The calculation formula for mud pressure support efficiency at the excavation face is: Where: is the mud pressure support efficiency at the excavation face, is the total area of mud pressure support, is the area of effective support range of mud pressure; It is worth noting that the area of the total range of mud pressure support is determined by the trapezoidal area calculation method. The area of the total range of mud pressure support includes the area of the effective mud pressure support range and the area of the ineffective mud pressure support range. The line formed by point C and the origin divides the trapezoidal area into two areas, such as Figure 4 As shown in the figure, when the effective support range of mud pressure is a triangle, the area of the effective support range of mud pressure is determined by the method of triangle area calculation; like Figure 3As shown, when the invalid support range of mud pressure is a triangle, the area of the effective support range of mud pressure is determined by subtracting the area of the invalid range of mud pressure support from the area of the total mud pressure support range. The invalid range of mud pressure support is a triangle, and the invalid support range is determined by calculating the area of the triangle.
[0016] The following is an example of the efficiency of mud pressure support in a slurry shield tunneling under certain working conditions.
[0017] The internal friction angle of the formation under this working condition is 30°, the shield diameter is 6m, the dissipation slope of the excess pore water pressure is 0.066kPa / mm, the excess pore water pressure of the upper cut of the shield top is 43.5 kPa, the dissipation distance is 0.659m, the excess pore water pressure of the lower cut of the shield bottom is 103.5kPa, the dissipation distance is 1.57m, and the mud support efficiency is 74.75%. The support efficiency of the mud pressure is simply and quickly calculated based on the dissipation slope of the excess pore water pressure in front of the excavation face and the internal friction angle parameters of the formation, verifying the feasibility of the calculation method of the mud pressure support efficiency at the excavation face.
[0018] In summary, the method for calculating the mud pressure support efficiency at the shield excavation face proposed in the present invention can simply and quickly calculate the support efficiency of the mud pressure according to the dissipation slope of the excess pore water pressure in front of the excavation face and the internal friction angle parameters of the formation, thereby providing a reference for the safety of slurry shield construction, thereby reducing the waste of mud and reducing the economic cost of construction while ensuring the safe and efficient construction of the slurry shield.
Claims
1. A method for calculating the slurry pressure support efficiency at the shield excavation face, characterized in that: The following steps are involved: S01. Calculate the dissipation distance of the excess pore water pressure at the top and bottom of the slurry shield excavation surface according to the dissipation slope of the excess pore water pressure in front of the slurry shield excavation surface, and determine the total range of the slurry pressure support; S02, according to the internal friction angle of the stratum excavated by the slurry shield Determine the extent of the potential sliding area ahead of the excavation face; S03. The overlapping area between the total mud pressure support range and the potential sliding area range is taken as the effective mud pressure support range; S04. The calculation formula for mud pressure support efficiency at the excavation face is: Where: is the mud pressure support efficiency at the excavation face, is the total area of mud pressure support, It is the area of effective support range of mud pressure.
2. The method for calculating the slurry pressure support efficiency at the shield excavation face according to claim 1, characterized in that: In step S01, the steps for calculating the dissipation distance of the excess pore water pressure at the top and bottom of the slurry shield excavation face are as follows: S0101. Convert the pore pressure-time relationship curve collected by the pore water pressure meter during the test into the pore pressure-distance relationship curve at different times and locations; S0102. Compare the change in pore water pressure on the pore pressure-distance relationship curve and its corresponding dissipation distance to obtain a dissipation slope; S0103. According to the geological characteristics of the slurry shield tunneling, the excess pore water pressure at the top and bottom cutouts of the slurry shield is calculated by using the water-soil combined calculation method or the water-soil separate calculation method. The dissipation distance of the excess pore water pressure at the top and bottom of the slurry shield excavation face is calculated based on the determined dissipation slope.
3. The method for calculating the slurry pressure support efficiency at the shield excavation face according to claim 1, characterized in that: In step S02, the internal friction angle of the stratum excavated by the slurry shield is determined by indoor triaxial compression test, direct shear test method, or obtained by static penetration test on site.
4. The method for calculating the slurry pressure support efficiency at the shield excavation face according to claim 1, characterized in that: In step S01, a plane coordinate system is established with the bottom of the slurry shield excavation surface as the origin, the forward direction of the excavation surface as the positive direction of the X axis, and the vertical upward direction of the excavated stratum as the positive direction of the Y axis; Take point A on the X-axis, point A is the dissipation distance of the excess pore water pressure at the bottom of the shield excavation surface, take point B on the plane coordinate system, the distance of point B on the Y-axis is the distance between the top and the bottom of the slurry shield excavation surface, and the distance of point B on the X-axis is the dissipation distance of the excess pore water pressure at the top of the shield excavation surface; A trapezoidal area is drawn on the plane coordinate system according to point A and point B, and the trapezoidal area is the total range of mud pressure support.
5. The method for calculating the slurry pressure support efficiency at the shield excavation face according to claim 4, characterized in that: In step S02, Take point C on the plane coordinate system. The distance of point C on the Y axis is the distance between the top and the bottom of the slurry shield excavation surface. The angle between the line formed by point C and the origin and the Y axis is 45°+ , A triangular area is drawn on the plane coordinate system according to the origin and point C. The triangular area and the square area directly above reaching the surface together form a wedge-shaped area, and the wedge-shaped area is the range of the potential sliding area; The line formed by point C and the origin divides the trapezoidal area into two areas. The area located obliquely below is the invalid range of mud pressure support.
6. The method for calculating the slurry pressure support efficiency at the shield excavation face according to claim 5, characterized in that: In step S04, The area of the total range of mud pressure support is determined by the trapezoidal area calculation method, and the area of the effective mud pressure support range is determined by the area of the total range of mud pressure support minus the area of the invalid range of mud pressure support. The invalid range of mud pressure support is a triangle, and the invalid support range is determined by the triangle area calculation method.