Rapid excavation method for finite space structure surface test section and capable of reducing disturbance

Abstract

The invention discloses a rapid excavation method for a finite space structure surface test section and capable of reducing disturbance. The rapid excavation method comprises the steps of determining the trend of a target structure surface, excavating a horn mouth, excavating a tunnel footage and trimming a blasting working surface. The innovation points of the invention are the application of the shockproof holes in the blasting process and the mode of combining the whole excavation operation with blasting and rock splitting by handheld hydraulic splitting equipment. According to the method, rapid operation of blasting in excavation engineering is utilized, the characteristic that hydraulic splitting equipment slightly disturbs a target structural plane in the rock splitting process is utilized, and meanwhile energy transmission of blasting bombardment waves in the direction of the target structural plane can be effectively prevented through the design of the anti-vibration holes. Through combination of anti-vibration holes, blasting and hydraulic splitting, the excavation method which ensures that a structural surface test section in a limited space is rapid and reduces disturbance is achieved, and the excavation method is effective for the current situation of the hydropower engineering industry with heavy tasks and tight construction periods at present.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of geotechnical test detection, and particularly relates to a rapid and disturbance-reducing excavation method for a test section of a structural plane in a limited space. BACKGROUND

[0002] A structural plane is a geological interface with certain forms and characteristics formed by various geological processes in a rock mass, and it is an important component of the rock mass, which has a significant influence on the physical and mechanical properties of the rock mass. The existence of the structural plane has a wide and far-reaching influence on underground engineering, and destroys the integrity, stability and impermeability of the rock mass. If the structural plane parameters cannot reflect the actual working conditions, it is easy to cause engineering instability or engineering investment expansion, so the control of the acquisition process of the structural plane parameters is particularly important.

[0003] At present, the in-situ direct shear test of the structural plane is one of the most important means to obtain effective structural plane strength parameters reflecting the actual conditions. According to the relevant research and regulations involving structural plane tests at home and abroad, such as the “Standard for Engineering Rock Mass Test Methods” (GB / T 50266-2013), “Rock Mass Test Regulations for Water and Hydropower Engineering” (DL / T 5368-2024), “The ISRMSuggested Methods for Rock Characterization, Testing and Monitoring: 2007-2014” and other relevant specifications, the direct shear test of the structural plane strength is involved, but there is no mention of the method of reducing disturbance during the excavation of the structural plane test section. In the relevant specifications of underground engineering excavation construction, such as “Code for Construction of Underground Excavation Engineering of Hydraulic Structures” (SL 378-2007) and “Technical Code for Blasting Construction of Water and Hydropower Engineering” (DL / T 5135-2015), the related excavation methods such as drill-and-blast method do not meet the requirements of structural plane test section excavation disturbance, and mechanical methods have slow excavation progress, large construction space requirements and poor hard rock excavation effect. There is also a new method of using water mill drill to finely excavate the structural plane test section. Compared with the mechanical method, this method solves the problem of light equipment, but still has the problems of low work efficiency and unsatisfactory hard rock excavation effect. Therefore, a new rapid and disturbance-reducing excavation method for the structural plane test section in a limited space is needed.

[0004] The patent application file with the publication number CN105157492A discloses a bedrock protection layer double pre-splitting controlled blasting structure and method. Two rows of pre-splitting holes are arranged at a certain distance from the excavation surface to separate the excavation surface into two main blasting areas, and each forms a main blasting hole, a buffer hole, and a pre-splitting hole arrangement sequence. When blasting, a micro-difference initiation network is used, and harmful factors such as blasting vibration are controlled. Two pre-splitting cracks are formed, and the two main blasting areas are detonated separately. The double pre-splitting controlled blasting method reduces the main seismic wave, overcomes the pre-splitting crack convergence characteristics, forms a better shock absorption effect to protect the bedrock, and has a large excavation volume per blasting cycle, which better solves the contradiction between efficient rock breaking and bedrock protection.

[0005] The patent application file with the publication number CN115929329A discloses a deep rock mass blasting damage control method based on multi-level energy regulation. The step method is used to excavate the deep buried chamber, and upper and lower steps are formed in the deep buried chamber after excavation. The blasting load is fully absorbed by the regulation retaining wall and energy dissipation cone, which reduces the damage to the reserved rock mass while ensuring the blasting effect and controls overbreak.

[0006] The patent application file with the publication number CN117052408A discloses a construction method for underground facilities. A rock protection layer is set between the rock stratum corresponding to the blasting area and the existing tunnel, and a damping hole is set on the rock protection layer to absorb vibration. This construction method can reduce the vibration of the explosive on the existing tunnel, thereby preventing the structure of the existing tunnel from being damaged, and the problem of segment falling off.

[0007] However, the above patent application files fail to solve the technical problem of reducing the disturbance of the test section of the structural plane, and lack a method for trimming the blasting working face after blasting. SUMMARY

[0008] To solve the above technical problems, the present application provides a rapid and low-disturbance excavation method for a test section of a structural plane in a limited space. This method is used to ensure that the test section excavation process is rapid and streamlined, while ensuring that the test section of the structural plane is disturbed to the lowest extent during the test section excavation process. The reliability of the strength test parameter acquisition process of the supporting structural plane ensures that the engineering test parameters can reflect the actual working conditions, providing a guarantee for the scientificity and rationality of subsequent engineering design.

[0009] The present application is realized by the following technical solutions.

[0010] The present application provides a rapid and low-disturbance excavation method for a test section of a structural plane in a limited space, comprising the following steps: S1: according to the survey outline file and the confirmation of the field geologist, the position of the target structure surface test section is determined in the existing tunnel, and then the strike of the target structure surface is predicted according to the trace of the tunnel wall structure surface, S2: a structure surface horn is excavated, the upper and lower boundaries of the structure surface horn are the upper boundary of the structure surface test section and the lower boundary of the structure surface test section, and the vibration-proof hole and the blasting hole are arranged during the excavation, and then the blasting is carried out to obtain the structure surface horn, S3: the footage of the structure surface test section is excavated based on the structure surface horn, and the upper boundary of the structure surface test section and the lower boundary of the structure surface test section are taken as boundaries, S4: the blasting working face is trimmed.

[0011] Preferably, the strike of the target structure surface can be determined by the exposed structure surface in the tunnel wall in step S1, and if there is no exposed structure surface, the strike of the target structure surface can be predicted by the extension direction of the trace of the tunnel wall structure surface on both sides of the tunnel wall.

[0012] Preferably, the opening of the structure surface test section in step S2 is in the shape of a horn, the vibration-proof hole is first punched on the rock mass, and then the blasting hole is punched, and the depth of the vibration-proof hole is greater than that of the blasting hole.

[0013] Preferably, the vibration-proof holes in step S2 are linearly arranged in three rows along the strike of the trace of the tunnel wall structure surface, and the distance from the trace of the tunnel wall structure surface includes the first row of vibration-proof holes, the second row of vibration-proof holes and the third row of vibration-proof holes from near to far, and the arrangement length of the three rows of vibration-proof holes covers the processing area of the structure surface test section to be retained.

[0014] Preferably, the second row of vibration-proof holes is arranged in a staggered manner with the first row of vibration-proof holes and the third row of vibration-proof holes.

[0015] Preferably, after the blasting, new vibration-proof holes are continuously punched in the direction of the structure surface test section excavation in a linear manner at the residual hole positions of the first row of vibration-proof holes, the second row of vibration-proof holes and the third row of vibration-proof holes in step S3, the new vibration-proof holes have the same specifications and spacing as the extended row of vibration-proof holes, and a second round of vibration-proof holes is formed.

[0016] Preferably, after the second round of vibration-proof holes is arranged, a second round of blasting holes is arranged in the same manner as in step S2, and the depth of the second round of vibration-proof holes is greater than that of the second round of blasting holes.

[0017] Preferably, the blasting hole in step S2 is arranged on the upper disc of the structure surface on the structure surface test section between the upper boundary of the structure surface test section and the lower boundary of the structure surface test section, the blasting hole includes a center hole and a surrounding hole around the center hole, the vibration-proof hole is arranged between the blasting hole and the trace of the tunnel wall structure surface, and the blasting step includes arranging explosives in the center hole and the surrounding hole and then blasting.

[0018] Preferably, the charge in the step S2 is initiated in the central hole before the charge in the peripheral hole.

[0019] Preferably, the blasting face is trimmed by hydraulic fracturing in the step S4, which includes inserting the fracturing gun head of the hydraulic fracturing device into the residual shockproof hole after initiation, and then fracturing the holes one by one.

[0020] The beneficial effects of the present application are: The application of the shockproof hole in the blasting process, and the combination of the blasting and the hand-held hydraulic fracturing device in the rock fracturing process are the innovations of the present application. The blasting is used for rapid operation in the excavation engineering, and the hydraulic fracturing device is used for the characteristics of the micro-disturbance to the target structure surface in the rock fracturing process. Meanwhile, the design of the shockproof hole can effectively prevent the transmission of the blasting shock wave to the target structure surface. The combination of the shockproof hole, the blasting and the hydraulic fracturing ensures the realization of the rapid and low-disturbance excavation method for the structure surface test section in the limited space, which is an effective method for the current heavy task and tight schedule of the hydropower and water conservancy industry. BRIEF DESCRIPTION OF DRAWINGS

[0021] Fig. 1 is a structural schematic diagram of the present application; Fig. 2 is the arrangement of the shockproof hole and the blasting hole of the present application; Fig. 3 is the effect diagram of the structure surface test section after the hydraulic fracturing of the present application; In the figure: 1-tunnel axis, 2-tunnel, 3-structure surface upper disc rock mass, 4-structure surface test section upper boundary, 5-structure surface test section lower boundary, 6-structure surface predicted trend, 7-tunnel wall structure surface trace, 8-structure surface lower disc rock mass, 9-first row of shockproof holes, 10-second row of shockproof holes, 11-third row of shockproof holes, 12-central hole, 13-peripheral hole. DETAILED DESCRIPTION

[0022] The technical solutions of the present application are further described below, but the scope of protection is not limited to the description.

[0023] Embodiment: A tunnel construction project in Tibet, a large number of structure surface direct shear tests are arranged on site, the structure surface direct shear test is arranged in the tunnel inside the mountain exploration, and the processing space of the target structure surface test section needs to be excavated through the construction operation. The disturbance to the target structure surface needs to be avoided as much as possible in the excavation process, so as to reduce the influence of the excavation process on the reliability of the test results. The rapid and low-disturbance excavation method for the structure surface test section under this working condition is as follows: As Figs. 1 to 3 shown, a rapid and low-disturbance excavation method for a structure surface test section in a limited space includes the following steps: S1: According to the survey outline file and the confirmation of the field geologist, the position of the target structural plane test section in the existing tunnel 2 is determined, and then the strike 6 of the target structural plane is predicted according to the tunnel wall structural plane trace 7; S2: A structural plane horn is excavated, the upper and lower boundaries of the structural plane horn are the upper boundary 4 of the structural plane test section and the lower boundary 5 of the structural plane test section, and the anti-vibration holes and the blasting holes are arranged during the excavation, and then the blasting is carried out to obtain the structural plane horn. S3: On the basis of the structural plane horn, the footage excavation of the structural plane test section is carried out, the upper boundary 4 of the structural plane test section and the lower boundary 5 of the structural plane test section are taken as boundaries, the blasting step in the footage excavation is the same as the blasting step in S2, and the area between the upper boundary 4 of the structural plane test section and the lower boundary 5 of the structural plane test section in the tunnel 2 is the structural plane test section, the thickness of the rock mass in the section is 30 cm, the tunnel wall structural plane trace 7 in the structural plane test section is the target structural plane, and the lower boundary 5 of the structural plane test section is away from the opening side of the tunnel. S4: The blasting working surface is trimmed.

[0024] In the step S1, the structural plane prediction strike 6 can be determined by the exposed structural plane in the tunnel wall, the structural plane prediction strike 6 of the tunnel can be found by using the geological compass according to the arranged structural plane direct shear test point, and if there is no exposed structural plane, the strike of the target structural plane can be inferred by the extension direction of the tunnel wall structural plane trace 7 appearing on both sides of the tunnel 2.

[0025] In the step S2, the opening of the structural plane test section is in the shape of a horn, the opening depth is not less than 1.5 m, the anti-vibration holes are first punched in the rock mass, and then the blasting holes are punched. The purpose of the horn excavation is to make a free surface for the target rock mass of the structural plane test section, so that the subsequent blasting working surface occurs along the predetermined contour. Fig. 1 The predetermined contour is the upper boundary 4 of the structural plane test section and the lower boundary 5 of the structural plane test section in the step S1.

[0026] In the step S2, three rows of anti-vibration holes are linearly arranged along the strike of the tunnel wall structural plane trace 7, the hole diameter of the anti-vibration hole is 42 mm, the hole depth is 2.5 m, the distance from the tunnel wall structural plane trace 7 includes the first row of anti-vibration holes 9, the second row of anti-vibration holes 10 and the third row of anti-vibration holes 11 from near to far, the hole depth of the three rows of anti-vibration holes is 0.5 m larger than the depth of the blasting hole, and the arrangement length of the three rows of anti-vibration holes covers the rock mass processing area of the structural plane test section to be reserved. The rock mass processing area of the structural plane test section is the rock mass between the lower boundary 5 of the structural plane test section and the tunnel wall structural plane trace 7.

[0027] The distance between the first row of shockproof holes 9 and the trace 7 of the hole wall structure surface is 30 cm, and the hole spacing of the first row of shockproof holes 9 is 10 cm; the distance between the second row of shockproof holes 10 and the trace 7 of the hole wall structure surface is 40 cm, and the hole spacing of the second row of shockproof holes 10 is 20 cm; the distance between the third row of shockproof holes 11 and the trace 7 of the hole wall structure surface is 50 cm, and the hole spacing of the third row of shockproof holes 11 is 30 cm. The second row of shockproof holes 10 is staggered with the first row of shockproof holes 9 and the third row of shockproof holes 11. The purpose of the shockproof hole is to absorb the blasting energy in the blasting process, reduce the impact disturbance of the blasting on the structure surface, and at the same time block the damage transmission.

[0028] Step S3 continues to extend linearly in the direction of the excavation of the structure surface test section on the residual hole positions of the first row of shockproof holes 9, the second row of shockproof holes 10, and the third row of shockproof holes 11 after the initiation of the charge, and new shockproof holes are drilled, which have the same specifications and spacing as the extended row of shockproof holes, forming a second round of shockproof holes.

[0029] After setting the second round of shockproof holes, a second round of blasting holes is set according to the same method as step S2, and the depth of the second round of shockproof holes is 0.5 m deeper than that of the second round of blasting holes.

[0030] The blasting hole in step S2 is set on the structure surface on the disc rock mass 3 between the upper boundary 4 of the structure surface test section and the lower boundary 5 of the structure surface test section, and the distance between the blasting hole and the trace 7 of the hole wall structure surface is 1.8 m. The blasting hole has a diameter of 42 mm and a depth of 2.0 m. The blasting hole includes a central hole 12 and surrounding holes 13. The shockproof hole is set between the blasting hole and the trace 7 of the hole wall structure surface. The initiation of the charge includes setting explosives in the central hole 12 and the surrounding holes 13 and then initiating. The process of charging and initiating adopts the method of multiple drilling and single-hole small charge, which aims to avoid the damage to the target structure surface caused by the excessive blasting shock wave due to one-time charging and initiating.

[0031] In the process of charging and initiating in step S2, the explosives in the central hole 12 are initiated before the explosives in the surrounding holes 13. The purpose of initiating the central hole 12 first is to groove, creating a free face for subsequent blasting operations, so that the minimum resistance line of subsequent blasting changes from the minimum distance from the blasting hole to the target structure surface to the minimum distance from the blasting hole center 12 to the artificially created free face, thereby reducing the disturbance of subsequent blasting on the target structure surface.

[0032] In step S4, the blasting working surface is trimmed by hydraulic fracturing, which includes inserting the fracturing gun head of a handheld hydraulic fracturing device into the residual shockproof holes after initiation, and then fracturing hole by hole. The device can use 42 mm air drill holes for rock mass fracturing. The blasting working surface trimmed by hydraulic fracturing can achieve the expected effect of the structure surface test section excavation.

Claims

1. A method for rapid and reduced-disturbance excavation of a test section of a limited space structure face, characterized in that, Includes the following steps: S1: Based on the survey outline document and the confirmation of the on-site geological personnel, determine the location of the target structural surface test section in the existing tunnel (2), and then predict its direction (6) based on the traces of the tunnel wall structural surface (7). S2: Excavate the funnel opening of the structural surface. The upper and lower boundaries of the funnel opening of the structural surface are the upper boundary (4) and the lower boundary (5) of the structural surface test section. During the excavation, anti-vibration holes and blasting holes are set, and then explosives are loaded and detonated to obtain the funnel opening of the structural surface. S3: On the basis of the flared opening of the structural surface, the structural surface test section is excavated, with the upper boundary (4) and the lower boundary (5) of the structural surface test section as the boundary; S4: Repair the blasting face.

2. The method for rapid and disturbance-reduced excavation of a test section of a confined space structural surface as described in claim 1, characterized in that: In step S1, the predicted orientation of the structural surface can be determined by the exposed structural surface in the tunnel wall (6). If there is no exposed structural surface, the orientation of the target structural surface can be inferred by the extension direction of the traces (7) of the tunnel wall structural surface that appear on both sides of the tunnel wall (2).

3. The method for rapid and disturbance-reduced excavation of a test section of a confined space structural surface as described in claim 1, characterized in that: In step S2, the opening of the structural surface test section is funnel-shaped. First, anti-vibration holes are drilled in the rock mass, and then blasting holes are drilled. The depth of the anti-vibration holes is greater than that of the blasting holes.

4. The method for rapid and disturbance-reduced excavation of a test section of a confined space structural surface as described in claim 1, characterized in that: In step S2, the anti-vibration holes are arranged in three rows in a linear fashion along the direction of the structural surface trace (7) of the tunnel wall. The anti-vibration holes are arranged in the first row (9), the second row (10), and the third row (11) from the nearest to the farthest from the structural surface trace (7). The length of the arrangement of the three rows of anti-vibration holes covers the processing area of ​​the test specimen of the structural surface test section that needs to be retained.

5. The method for rapid and disturbance-reduced excavation of a test section of a confined space structural surface as described in claim 4, characterized in that: The second row of anti-vibration holes (10) is staggered with the first row of anti-vibration holes (9) and the third row of anti-vibration holes (11).

6. The method for rapid and disturbance-reduced excavation of a test section of a confined space structural surface as described in claim 4, characterized in that: In step S3, after the charge is detonated, new anti-vibration holes are drilled linearly in the direction of excavation of the test section of the structural surface on the remaining holes of the first row of anti-vibration holes (9), the second row of anti-vibration holes (10), and the third row of anti-vibration holes (11). The new anti-vibration holes have the same specifications and spacing as the anti-vibration holes in the extended row, forming the second round of anti-vibration holes.

7. The method for rapid and disturbance-reduced excavation of a test section of a confined space structural surface as described in claim 6, characterized in that: After setting the second round of anti-vibration holes, set the second round of blasting holes in the same way as in step S2, wherein the depth of the second round of anti-vibration holes is greater than that of the second round of blasting holes.

8. The method for rapid and disturbance-reduced excavation of a test section of a confined space structural surface as described in claim 1, characterized in that: In step S2, the blasting hole is set on the hanging wall rock mass (3) between the upper boundary (4) and the lower boundary (5) of the structural surface test section. The blasting hole includes a central hole (12) and surrounding peripheral holes (13). The anti-vibration hole is set between the blasting hole and the structural surface trace (7) of the tunnel wall. The charging and detonation step includes setting explosives in the central hole (12) and surrounding holes (13) and then detonating.

9. The method for rapid and disturbance-reduced excavation of a test section of a confined space structural surface as described in claim 8, characterized in that: During the detonation process in step S2, the explosive in the central hole (12) detonates before the explosive in the peripheral holes (13).

10. The method for rapid and disturbance-reduced excavation of a test section of a confined space structural surface as described in claim 1, characterized in that: In step S4, the blasting working face is trimmed by hydraulic splitting. The steps include inserting the splitting gun head of the hydraulic splitting equipment into the residual anti-vibration holes after detonation, and then splitting the holes one by one.

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