A tunnel construction fissure water precision detection method based on a super flat guide

Abstract

This invention discloses a method for accurate detection of fissure water in tunnel construction based on a pilot tunnel. During tunnel construction in challenging mountainous areas, the geological environment ahead of the main tunnel face is complex and variable. This invention includes: determining the location of the low-resistivity zone in the area to be excavated in the main tunnel of a high-risk tunnel; measuring multiple sets of fissure structures in the exposed rock mass of both the pilot tunnel and the main tunnel face, and selecting the dominant fissure structures from these sets; comparing the orientation information of the dominant fissure structures on the pilot tunnel and the main tunnel face; when the difference in strike and dip angle between the dominant fissure structures on the pilot tunnel and the main tunnel face is less than an acute angle, the average of the strike and dip angles of this set is taken as the orientation information of the fissure structure; and calculating the location of fissure water inflow in the area to be excavated in the main tunnel. This invention solves the problems of insufficient utilization of the pilot tunnel in high-risk tunnels and inaccurate prediction of the location of fissure water inflow in the area to be excavated in the main tunnel.

Description

Technical Field

[0001] This invention belongs to the field of tunnel advanced geological prediction technology, specifically involving a method for accurate detection of fracture water in tunnel construction based on advanced pilot tunneling. Background Technology

[0002] Transient electromagnetic method (TEM), as an electromagnetic induction method, is highly sensitive to low-resistivity, water-filled, fractured zones. It is an effective short-range groundwater prediction method, and low-resistivity zones are often areas where water bodies are distributed. The effective detection distance is approximately 60 meters. In tunnel construction, the TEM application face is often the tunnel face. This invention uses advanced pilot-guided lateral assessment to determine the water content of the area to be excavated in the main tunnel and the surrounding rock mass.

[0003] When constructing tunnels in challenging mountainous areas, the geological environment ahead of the main tunnel face is complex and variable, often containing bedrock fissure water. During construction, a parallel pilot tunnel with a smaller cross-section, typically excavated about 10-30 meters away from the main tunnel (referred to as an advance pilot tunnel), is usually excavated to proactively identify unknown water inrush risks. This method is more intuitive and accurate than geophysical exploration. However, current methods mostly rely on parallel extrapolation of the same mileage to predict the water inrush conditions of the main tunnel, failing to fully utilize the advance advantages of the advance pilot tunnel.

[0004] Bedrock fissure water is mostly found in the fissure structural surfaces, forming interconnected spaces for water bodies. By extrapolating the spatial distribution of the pilot tunnel towards the main tunnel from the perspective of the geological formation patterns of the fissure structural surfaces, the water content in the area to be excavated in the main tunnel can be accurately predicted. This is of great significance for the prediction and prevention of sudden water inrush risks during tunnel excavation and construction. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a method for accurate detection of fissure water in tunnel construction based on advanced pilot tunnels. Starting from the geological formation law of fissure structures, it solves the problems of insufficient utilization of advanced pilot tunnels in high-risk tunnels and inaccurate prediction of the location of fissure water inrush in the tunnel's main excavation area.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for accurate detection of fracture water in tunnel construction based on advanced pilot tunneling includes the following steps:

[0008] S1: Determine the location of the low-resistivity zone in the area to be excavated in the main tunnel of a high-risk tunnel;

[0009] S2: Measure multiple sets of fracture structure surfaces in the exposed rock mass at the working face of the pilot tunnel and the main tunnel, and select the dominant fracture structure surface from the multiple sets of fracture structure surfaces.

[0010] S3: Compare the orientation information of the dominant fracture structure surface at the working face of the pilot tunnel and the main tunnel. When the difference between the orientation and dip angle of the dominant fracture structure surface at the working face of the pilot tunnel and the main tunnel is less than an acute angle, take the average value of the orientation and dip angle of this group and use it as the orientation information of the fracture structure surface.

[0011] S4: Based on the location of the low-resistivity zone measured in S1, calculate the location of fissure water inflow in the tunnel's main excavation area.

[0012] Furthermore, the specific method of step S1 is as follows:

[0013] S1-1: Transient electromagnetic method is used to detect the unexcavated section of the tunnel main tunnel facing the sidewall of the tunnel advance pilot tunnel.

[0014] S1-2: Analyze the spatial distribution and changes of resistivity based on transient electromagnetic detection data to determine the location of the low-resistivity region.

[0015] Furthermore, the specific method of step S2 is as follows:

[0016] S2-1: Measure multiple sets of fracture structure surfaces in the exposed bedrock at the working face of the advanced pilot tunnel and record the attitude information;

[0017] S2-2: Measure multiple sets of fracture structure surfaces in the exposed bedrock at the tunnel face and record the attitude information;

[0018] S2-3: Compare the on-site working face conditions among the multiple sets of fracture structure surfaces in S2-1 and S2-2. Based on the principle of selecting the longest fracture length, select two sets of fracture structure surfaces as the dominant fracture structure surfaces in each case. The attitude information of the first and second sets of dominant fracture structure surfaces in the pilot tunnel is recorded as Ja and Jb, respectively. The attitude information of the first and second sets of dominant fracture structure surfaces in the main tunnel is recorded as Ja' and Jb', respectively.

[0019] Furthermore, the attitude information includes the orientation and dip angle of the fracture structure planes.

[0020] Furthermore, the specific method of step S3 is as follows:

[0021] Step S3-1: The attitude information Ja' and Jb' of the dominant fracture structure surface at the tunnel face and the two sets of attitude information Ja and Jb of the dominant fracture structure surface at the pilot tunnel face are compared alternately, namely Ja' and Ja, Ja' and Jb, Jb' and Ja, Jb' and Jb;

[0022] Step S3-2: If the orientation (strike and dip angle) of the fracture structure surface at the working face of the pilot tunnel and the main tunnel are both less than acute angles, name the orientation corresponding to the pilot tunnel J1 and the orientation corresponding to the main tunnel J1'. Take the average of the strike of J1 and the strike of J1' as the strike of the fracture structure surface J1”, and take the average of the dip angle of J1 and the dip angle of J1' as the dip angle of the fracture structure surface J1”.

[0023] Step S3-3: If the difference in orientation and dip angle between the pilot tunnel face and the main tunnel face is greater than an acute angle, find new dominant fracture structure surfaces for the pilot tunnel face and the main tunnel face, and repeat steps S2 and S3 until the conditions are met.

[0024] Furthermore, the specific method of step S4 is as follows:

[0025] S4-1: Determine the relative position of the measured low-resistivity zone and the main tunnel based on S1-2;

[0026] S4-2: Based on the orientation information of the fracture structure surface through S3-2, the width and distance between the pilot tunnel and the main tunnel, and the mileage of the low-resistivity zone, calculate the location of the fracture water inrush in the area to be excavated in the main tunnel.

[0027] Furthermore, in step S4-2, if the center position of the low-resistivity zone measured in S1 is outside the tunnel main tunnel, then the distance from the low-resistivity zone to the leading guide sidewall is y2, which is greater than the distance y1 between the guide sidewall and the sidewall on the same side of the main tunnel. Based on the orientation of the penetrating fracture structure surface J1", and its direction, the starting position of the water inrush in the tunnel main tunnel can be accurately predicted as x = x1 + (y2 - y1)tanα ~ x2 + (y2 - y1)tanα, where α is the angle between the orientation of the penetrating fracture structure surface and the plane where the tunnel main tunnel face is located.

[0028] Furthermore, in step S4-2, if the center position of the low-resistivity zone measured in S1 is within the outline of the tunnel main tunnel, then the distance from the low-resistivity zone to the leading guide sidewall is y2, which is less than the distance y1 between the guide sidewall and the sidewall on the same side of the main tunnel, but not less than the distance between the guide and the main tunnel. By observing the orientation of the penetrating fracture structure surface J1", based on its direction and the mileage x1 and mileage x2 of the low-resistivity zone, the starting position of the water inrush in the tunnel main tunnel fracture can be accurately predicted as x = x1-(y1-y2)tanα ~ x2-(y1-y2)tanα, where α is the angle between the orientation of the penetrating fracture structure surface and the plane where the tunnel main tunnel face is located.

[0029] Furthermore, in step S4-2, if the center position of the low-resistivity zone measured in S1 is within the outline of the tunnel main tunnel, then the distance of the low-resistivity zone from the sidewall of the advanced guide is y2, which is less than the distance between the guide and the main tunnel. Based on the orientation of the penetrating fracture structure surface J1", and its direction, the starting position of the water inrush in the tunnel main tunnel can be accurately predicted as x = x1-(y1-y2)tanα ~ x2-(y1-y2)tanα, where α is the angle between the orientation of the penetrating fracture structure surface and the plane where the tunnel main tunnel face is located.

[0030] The beneficial effects of this invention are:

[0031] 1) This invention fully utilizes the advantages of advanced pilot tunneling in high-risk tunnels to predict the water content of bedrock fissures in the tunnel excavation area over long distances, providing ample time for tunnel construction and excavation to prepare water hazard prevention measures in advance.

[0032] 2) Starting from the relationship between the structural surfaces of the tunnel advance pilot and the tunnel main tunnel, this invention predicts the development of fracture structural surfaces in the unknown area between the tunnel advance pilot and the tunnel main tunnel, and provides a deduction method that penetrates the fracture structural surfaces.

[0033] 3) This invention uses the geological development law of fracture structure surface to perform spatial extrapolation of the advanced pilot tunnel to the main tunnel. Compared with the traditional method of advancing the pilot tunnel to the main tunnel at the same distance, it helps to accurately predict the water situation in the area to be excavated in the main tunnel, providing an advanced signal for the prevention and control of water hazards during tunnel excavation and ensuring the safety of tunnel construction. Attached Figure Description

[0034] Figure 1 This is a schematic diagram illustrating the principle of the method of the present invention;

[0035] Figure 2 This is a schematic diagram of the transient electromagnetic detection of the present invention;

[0036] Figure 3 This is a schematic diagram showing the orientation of the advantageous structural surface at the tunnel face of the advanced pilot tunnel and the main tunnel face of the present invention.

[0037] Figure 4 This is a schematic diagram of the orientation of the through-fracture structure surface of the present invention;

[0038] Figure 5 This is a schematic diagram showing the center location of the low-resistivity zone measured in this invention on the outside of the main tunnel.

[0039] Figure 6 This is a schematic diagram showing the center location of the low-resistivity zone measured in this invention within the outline of the tunnel's main tunnel.

[0040] Figure 7 This is a schematic diagram showing the center location of the low-resistivity zone measured in this invention inside the main tunnel. Detailed Implementation

[0041] The present invention will now be described in detail with reference to specific embodiments.

[0042] This invention utilizes transient electromagnetic methods to achieve efficient prediction of fissure water in the unexcavated area of ​​the tunnel's pilot tunnel facing the main tunnel, based on the geological formation process.

[0043] A schematic diagram of the principle of the method of this invention is shown below. Figure 1 As shown, the present invention provides a method for precise detection of fracture water in tunnel construction based on advanced pilot tunneling, comprising the following steps:

[0044] S1: Determine the location of the low-resistivity zone in the area to be excavated in the main tunnel of a high-risk tunnel;

[0045] S2: Measure multiple sets of fracture structure surfaces in the exposed rock mass at the face of the pilot tunnel and the main tunnel, and select the dominant fracture structure surface from the multiple sets of fracture structure surfaces.

[0046] S3: Compare the orientation information of the dominant fracture structure surface at the working face of the pilot tunnel and the main tunnel. When the difference between the orientation and dip angle of the dominant fracture structure surface at the working face of the pilot tunnel and the main tunnel is less than an acute angle, take the average value of the orientation and dip angle of this group and use it as the orientation information of the fracture structure surface.

[0047] S4: Based on the location of the low-resistivity zone measured in S1, calculate the location of fissure water inflow in the tunnel's main excavation area. The specific method is as follows:

[0048] S4-1: Determine the relative position of the measured low-resistivity zone and the main tunnel based on S1-2;

[0049] S4-2: Based on the orientation information of the fracture structure surface through S3-2, the width and distance between the pilot tunnel and the main tunnel, and the mileage of the low-resistivity zone, calculate the location of the fracture water inrush in the area to be excavated in the main tunnel. Specific implementation examples:

[0051] Step S1: Use transient electromagnetic methods to probe the area to be excavated in the main tunnel on the sidewall of the pilot tunnel to determine the location of the low-resistivity zone, which is the possible location of the disaster-causing water body; such as Figure 2 As shown, the specific method is as follows:

[0052] S1-1: Transient electromagnetic method is used to detect the unexcavated section of the main tunnel of a high-risk tunnel facing the sidewall of the tunnel advance pilot tunnel.

[0053] S1-2: Analyze the spatial distribution and changes of resistivity based on transient electromagnetic detection data to determine the location of the low-resistivity zone; the mileage in front of the low-resistivity zone is recorded as x1, and the mileage behind the low-resistivity zone is recorded as x2.

[0054] Step S2: Identify relatively obvious structural surfaces in the exposed rock mass of the main tunnel and the pilot tunnel face, and select two sets of obvious and intuitive fracture structural surfaces as the dominant fracture structural surfaces; the specific method is as follows:

[0055] S2-1: Measure multiple sets of fracture structure surfaces in the exposed bedrock at the working face of the advanced pilot tunnel, and record the attitude information, including the strike and dip angle of the fracture structure surfaces;

[0056] S2-2: Measure multiple sets of fracture structure surfaces in the exposed bedrock at the tunnel face and record the attitude information;

[0057] S2-3: Comparing the on-site working face conditions among the multiple sets of fracture structure surfaces in S2-1 and S2-2, and selecting two sets of fracture structure surfaces from each group as dominant fracture structure surfaces based on the principle of selecting the longest fracture length, the attitude information of the first and second sets of dominant fracture structure surfaces in the pilot tunnel is denoted as Ja and Jb, respectively, and the attitude information of the first and second sets of dominant fracture structure surfaces in the main tunnel is denoted as Ja' and Jb', respectively. Figure 3 As shown.

[0058] S3: Compare the attitude information of the dominant fracture structure surfaces at the working face of the pilot tunnel and the main tunnel to determine the attitude information of the fracture structure surfaces that penetrate the tunnel; the specific method is as follows:

[0059] Step S3-1: The attitude information Ja' and Jb' of the dominant fracture structure surface at the tunnel face and the two sets of attitude information Ja and Jb of the dominant fracture structure surface at the pilot tunnel face are compared alternately, namely Ja' and Ja, Ja' and Jb, Jb' and Ja, Jb' and Jb;

[0060] Step S3-2: If the orientation (strike and dip angle) of the fracture structure surface at the working face of the pilot tunnel and the main tunnel are both less than acute angles, name the orientation corresponding to the pilot tunnel J1 and the orientation corresponding to the main tunnel J1'. Take the average of the strike of J1 and the strike of J1' as the strike of the fracture structure surface orientation J1', and take the average of the dip angles of J1 and J1' as the dip angle of the fracture structure surface orientation J1'. Figure 4 As shown;

[0061] Step S3-3: If the difference in orientation and dip angle between the pilot tunnel face and the main tunnel face is greater than an acute angle, find new dominant fracture structure surfaces for the pilot tunnel face and the main tunnel face, and repeat steps S2 and S3 until the conditions are met.

[0062] S4: The location of the low-resistivity zone measured in S1 may be outside the tunnel main tunnel, inside the tunnel main tunnel outline, or inside the tunnel main tunnel. Based on the location of the low-resistivity zone measured in S1, the location of fissure water inflow in the tunnel main tunnel to be excavated area is calculated. The specific method is as follows:

[0063] S4-1: Determine the relative position of the measured low-resistivity zone and the main tunnel based on S1-2;

[0064] S4-2: Based on the orientation information of the fracture structure surface through S3-2, the width and distance between the pilot tunnel and the main tunnel, and the mileage of the low-resistivity zone, calculate the location of the fracture water inrush in the area to be excavated in the main tunnel.

[0065] 1) In step S4-2, if the center of the low-resistivity zone measured in S1 is located outside the main tunnel, such as Figure 5 As shown, at this time, the distance from the low-resistivity zone to the advanced guide sidewall is y2, which is greater than the distance y1 between the guide sidewall and the sidewall on the same side of the main tunnel. Based on the orientation of the penetrating fracture structure surface J1”, and its direction, the starting position of the water inrush in the tunnel main tunnel can be accurately predicted as x = x1 + (y2 - y1)tanα ~ x2 + (y2 - y1)tanα, where α is the angle between the orientation of the penetrating fracture structure surface and the plane where the tunnel main tunnel face is located.

[0066] 2) In step S4-2, if the center position of the low-resistivity zone measured in S1 is within the outline of the tunnel main shaft, such as Figure 6 As shown, at this time, the distance from the low-resistivity zone to the advanced guide sidewall is y2, which is less than the distance y1 between the guide sidewall and the sidewall on the same side of the main tunnel, but not less than the distance between the guide and the main tunnel. Based on the orientation of the penetrating fracture structure surface J1", according to its direction and the mileage x1 in front of the low-resistivity zone and the mileage x2 in back of the low-resistivity zone, the starting position of the fracture water inrush in the main tunnel can be accurately predicted as x = x1-(y1-y2)tanα ~ x2-(y1-y2)tanα, where α is the angle between the orientation of the penetrating fracture structure surface and the plane where the tunnel face is located.

[0067] 3) In step S4-2, if the center of the low-resistivity zone measured in S1 is inside the main tunnel, such as Figure 7 As shown, at this time, the distance from the low-resistivity zone to the sidewall of the advanced guide is y2, which is less than the distance between the guide and the main tunnel. By observing the orientation of the penetrating fracture structure surface J1", based on its direction and the mileage x1 on the front side of the low-resistivity zone and the mileage x2 on the rear side of the low-resistivity zone, the starting position of the fracture water inrush in the main tunnel can be accurately predicted as x = x1-(y1-y2)tanα ~ x2-(y1-y2)tanα, where α is the angle between the orientation of the penetrating fracture structure surface and the plane where the tunnel face is located.

[0068] 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 precise detection of fracture water in tunnel construction based on advanced pilot tunneling, characterized in that: Includes the following steps: S1: Determine the location of the low-resistivity zone in the area to be excavated in the main tunnel of a high-risk tunnel; S2: Measure multiple sets of fracture structure surfaces in the exposed rock mass at the working face of the pilot tunnel and the main tunnel, and select the dominant fracture structure surface from the multiple sets of fracture structure surfaces. S3: Compare the orientation information of the dominant fracture structure surface at the working face of the pilot tunnel and the main tunnel. When the difference between the orientation and dip angle of the dominant fracture structure surface at the working face of the pilot tunnel and the main tunnel is less than an acute angle, take the average value of the orientation and dip angle of the dominant fracture structure surface at the working face of the pilot tunnel and the main tunnel, and use it as the orientation information of the fracture structure surface. S4: Based on the location of the low-resistivity zone measured in S1, calculate the location of fissure water inflow in the tunnel's main tunnel excavation area; The specific method for step S4 is as follows: Based on the measured relative position of the low-resistivity zone and the main tunnel, the attitude information of the penetrating fracture structure surface, the width and distance between the pilot tunnel and the main tunnel, and the mileage of the low-resistivity zone, the location of the fracture water inrush in the area to be excavated in the main tunnel is calculated.

2. The method for precise detection of fracture water in tunnel construction based on advanced pilot tunneling as described in claim 1, characterized in that: The specific method for step S1 is as follows: S1-1: Transient electromagnetic method is used to detect the unexcavated section of the tunnel main tunnel facing the sidewall of the tunnel advance pilot tunnel. S1-2: Analyze the spatial distribution and changes of resistivity based on transient electromagnetic detection data to determine the location of the low-resistivity region.

3. The method for precise detection of fracture water in tunnel construction based on advanced pilot tunneling as described in claim 2, characterized in that: The specific method for step S2 is as follows: S2-1: Measure multiple sets of fracture structure surfaces on the exposed bedrock at the working face of the advanced pilot tunnel and record the attitude information; S2-2: Measure multiple sets of fracture structure surfaces on the exposed bedrock at the tunnel face and record their attitude information; S2-3: Comparing the multiple sets of fracture structure surfaces and the on-site working face conditions of S2-1 and S2-2, based on the principle of selecting the longest fracture length, two sets of fracture structure surfaces were selected as the dominant fracture structure surfaces for each. The attitude information of the first and second sets of dominant fracture structure surfaces in the pilot tunnel is denoted as Ja and Jb, respectively, and the attitude information of the first and second sets of dominant fracture structure surfaces in the main tunnel is denoted as Ja' and Jb', respectively.

4. The method for precise detection of fracture water in tunnel construction based on advanced pilot tunneling as described in claim 3, characterized in that: Attitude information includes the orientation and dip angle of fracture structure planes.

5. The method for precise detection of fracture water in tunnel construction based on advanced pilot tunneling as described in claim 4, characterized in that: The specific method for step S3 is as follows: Step S3-1: Compare the attitude information Ja', Jb' of the dominant fracture structure surface at the tunnel face with the two sets of attitude information Ja, Jb of the dominant fracture structure surface at the pilot tunnel face in turn, i.e. Ja' and Ja, Ja' and Jb, Jb' and Ja, Jb' and Jb; Step S3-2: If the difference between the strike and dip angle of the fracture structure surface at the working face of the pilot tunnel and the main tunnel is less than an acute angle, name the corresponding attitude of the pilot tunnel J1 and the corresponding attitude of the main tunnel J1'. Take the average of the strike of J1 and the strike of J1' as the strike of the fracture structure surface J1”, and take the average of the dip angle of J1 and the dip angle of J1' as the dip angle of the fracture structure surface J1”. Step S3-3: If the difference in orientation and dip angle between the pilot tunnel face and the main tunnel face is greater than an acute angle, find new dominant fracture structure surfaces for the pilot tunnel face and the main tunnel face, and repeat steps S2 and S3 until the conditions are met.

6. The method for precise detection of fracture water in tunnel construction based on advanced pilot tunneling as described in claim 5, characterized in that: If the center of the low-resistivity zone measured by S1 is outside the main tunnel, then the distance from the low-resistivity zone to the leading guide sidewall is y2, which is greater than the distance y1 between the guide sidewall and the sidewall on the same side of the main tunnel. Based on the orientation of the penetrating fracture structure surface J1”, and combined with the mileage x1 on the front side of the low-resistivity zone and the mileage x2 on the rear side of the low-resistivity zone, the starting position of the fracture water inrush in the main tunnel can be accurately predicted as x=x1+(y2-y1)tanα~x2+(y2-y1)tanα, where α is the angle between the orientation of the penetrating fracture structure surface and the plane where the tunnel face is located.

7. The method for precise detection of fracture water in tunnel construction based on advanced pilot tunneling as described in claim 6, characterized in that: If the center of the low-resistivity zone measured by S1 is within the outline of the tunnel main tunnel, then the distance from the low-resistivity zone to the leading guide sidewall is y2, which is less than the distance y1 between the guide sidewall and the sidewall on the same side of the main tunnel, but not less than the distance between the guide and the main tunnel. Based on the orientation of the penetrating fracture structure surface J1”, and combined with the mileage x1 ahead of the low-resistivity zone and the mileage x2 behind the low-resistivity zone, the starting position of the fracture water inrush in the tunnel main tunnel can be accurately predicted as x=x1-(y1-y2)tanα~x2-(y1-y2)tanα, where α is the angle between the orientation of the penetrating fracture structure surface and the plane where the tunnel main tunnel face is located.

8. The method for precise detection of fracture water in tunnel construction based on advanced pilot tunneling as described in claim 7, characterized in that: If the center of the low-resistivity zone measured by S1 is inside the tunnel main tunnel, then the distance of the low-resistivity zone from the sidewall of the leading guide is y2, which is less than the distance between the guide and the main tunnel. Based on the orientation of the penetrating fracture structure surface J1”, and combined with the mileage x1 on the front side of the low-resistivity zone and the mileage x2 on the rear side of the low-resistivity zone, the starting position of the water inrush in the tunnel main tunnel fracture can be accurately predicted as x=x1-(y1-y2)tanα~x2-(y1-y2)tanα, where α is the angle between the orientation of the penetrating fracture structure surface and the plane where the tunnel main tunnel face is located.

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