Hard rock tunnel excavation section anchoring and pulling construction method

Abstract

This invention relates to the technical field of tunnel construction methods, and in particular to a method for anchoring and pulling out anchors in the excavation section of a hard rock tunnel. The method includes the following steps: S1, setting the outline of the excavated rock mass and creating a weakened structural surface along the outline; S2, driving several anchor rods into the excavated rock mass and creating a rock mass structural surface with several anchor rod ends; S3, using construction machinery to pull out the anchor rods; S4, removing slag; S5, subsequent rock mass support. This invention features simple process steps, a reasonable design, convenient construction, and good performance. It can easily complete the excavation and construction process of hard rock tunnels, ensuring safety and guaranteeing the construction period.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction methods, and in particular to a method for anchoring and pulling out sections of hard rock tunnels during excavation. Background Technology

[0002] In rock conditions, there are two main types of methods commonly used for hard rock tunnel excavation. The first type is the drill-and-blast method, which involves drilling holes of a certain diameter and depth into the rock mass, loading them with explosives, and then blasting the rock to excavate it. This method is widely used because it is highly adaptable and relatively economical.

[0003] However, drilling and blasting methods cause significant disturbance to the surrounding rock, easily leading to rockfalls or even tunnel collapses. Furthermore, blasting excavation can easily result in over-excavation of the excavation section, leading to excessive shotcrete volume and increased construction costs. In shallow-buried sections or areas with surface structures, blasting vibrations can easily damage these structures.

[0004] The second type of method is the non-explosive mechanical method, which uses large TBMs, cantilever tunneling machines, and hydraulic breakers for excavation. The significant advantages of mechanical excavation are low vibration and noise, minimal disturbance to the surrounding environment, good control of over- and under-excavation along the tunnel contour, and safety and environmental friendliness. However, large TBMs are costly, inconvenient to transport, and only suitable for large-scale projects such as long-distance tunnels; they are not suitable for the numerous small and medium-sized tunnels. Small excavation equipment such as cantilever tunneling machines and hydraulic breakers have limited operational capabilities, low construction efficiency, rapid tool wear, and poor economic efficiency, thus limiting the use of this method in hard rock conditions.

[0005] However, with the increasing density of infrastructure construction, more and more tunnel projects are being built through or adjacent to existing buildings. The use of explosive drilling and blasting methods is restricted due to poor control of over- and under-excavation, high vibration and noise levels, high dust concentrations, and the release of harmful gases. Non-explosive mechanical methods such as cantilever tunnel boring machines (TBMs) can effectively solve these problems; however, for hard rock, the low construction efficiency of TBMs is a significant drawback. Therefore, there is an urgent need for a method of anchoring and pulling out the excavation section in hard rock tunnels to address this issue. Summary of the Invention

[0006] The purpose of this invention is to provide a method for anchoring and pulling out sections of hard rock tunnels during excavation, in order to solve the above-mentioned problems.

[0007] To achieve the above objectives, the present invention provides the following solution:

[0008] The anchoring and pull-out construction method for the excavated section of a hard rock tunnel includes the following steps:

[0009] S1. Set the outline of the excavated rock mass and create a weakened structural surface along the outline of the excavated rock mass;

[0010] S2. Drive several anchor rods into the excavated rock mass to create a rock mass structure surface with several ends of the anchor rods.

[0011] S3. Use construction machinery to pull out several of the anchor bolts;

[0012] S4, slag removal;

[0013] S5. Later-stage rock mass support.

[0014] Preferably, the creation of the weakened structural surface of the excavated rock mass outline in S1 includes the following steps:

[0015] S101, Geological survey of rock stratigraphy;

[0016] S102. Create the outline of the excavated rock mass;

[0017] S103. Drill several holes along the outline of the excavated rock mass.

[0018] S104. The pre-splitting blasting of the borehole generates artificial rock mass cracks of a certain depth, and the artificial rock mass cracks are chemically corroded.

[0019] Preferably, in step S102, the range of the excavated rock mass outline is set according to the single-cycle excavation advance and the length of the anchor rod. The single-cycle excavation advance and the length of the anchor rod are compared to obtain the smaller value between the two. When the single-cycle excavation advance is less than the length of the anchor rod, the excavated rock mass outline is 3cm to 6cm greater than the single-cycle excavation advance.

[0020] When the single-cycle excavation advance is greater than the length of the anchor rod, the outline of the excavated rock mass is 3cm to 6cm longer than the length of the anchor rod.

[0021] Preferably, in step S103, the depth of the borehole is the same as the depth of the single-cycle excavation advance.

[0022] Preferably, in step S104, the borehole is set perpendicular to the wall of the excavated rock mass.

[0023] Preferably, in step S104, the artificial rock mass cracks are chemically corroded using a static expansion agent.

[0024] Preferably, in step S2, driving a plurality of anchor bolts into the excavated rock mass includes the following steps:

[0025] S201. A plurality of anchor bolt holes are set in the excavated rock mass, and the anchor bolt holes are set perpendicular to the wall of the excavated rock mass;

[0026] S202. Drive the anchor bolt into the anchor bolt hole;

[0027] S203. Grout the anchor bolt to anchor it to the excavated rock mass.

[0028] Preferably, in step S2, a flammable cartridge is placed at one end of the anchor bolt located within the excavated rock mass, and the flammable cartridge is used to weaken the tensile strength of the rock mass at the end of the anchor bolt.

[0029] Preferably, in step S3, several of the anchor bolts are pulled out sequentially using a mechanical pulling method.

[0030] The present invention has the following technical effects: When using this method to break up hard rock, firstly, an outline of the excavated rock mass is created to delineate the rock mass to be excavated. Then, a weakened structural surface is created along the outline of the excavated rock mass. This weakened structural surface will form cracks around the excavated rock mass. Subsequently, several anchor rods are driven into the excavated rock mass, with one end extending into the excavated rock mass and the other end remaining on the outside of the excavated rock mass, forming a rock mass structural surface with several anchor rod ends. Then, the anchor rods are removed by mechanical pulling. One end of the anchor rod is anchored to the inside of the excavated rock mass. Under the action of the cracks formed by the weakened structural surface of the excavated rock mass outline, the excavated rock mass is broken at the cracks, thereby achieving the breaking and excavation of hard rock. This method features simple and rationally designed steps, convenient construction, and good performance. By using anchor bolts to pull and excavate the rock mass in the area to be excavated and the entire tunnel excavation outline, it avoids over-excavation and under-excavation, resulting in a regular excavation face shape. This reduces waste of shotcrete caused by over-excavation and avoids the negative impacts of drill-and-blast methods, such as noise, dust, and ground vibration. It also minimizes disturbance to the surrounding rock and reduces the risk of boulders and falling rocks. Excavation is rapid and flexible; the size and shape of the excavated underground space cross-section can be varied. In summary, this invention features simple and rationally designed steps, convenient construction, and good performance. It can easily complete the hard rock tunnel excavation process, ensuring safety and guaranteeing the construction period. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a flowchart of the construction process of the present invention;

[0033] Figure 2 This is a schematic diagram of the excavation process of the present invention;

[0034] Figure 3 For the present invention Figure 2Schematic diagram of section 1-1;

[0035] Figure 4 This is a schematic diagram of the anchor bolt structure of the present invention;

[0036] Among them, 1. Excavated rock mass outline; 2. Excavated rock mass; 3. Artificial rock mass cracks; 4. Anchor bolt drilling; 5. Anchor bolt; 6. Mechanical pull-out direction; 501. Nut; 502. Grout stop plug; 503. Hollow rod body; 504. Rubber head end. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] refer to Figures 1 to 4 This invention provides a method for anchoring and pulling out sections of hard rock tunnels during excavation, comprising the following steps:

[0040] S1. Set the outline of the excavated rock mass 1, and create a weakened structural surface along the outline of the excavated rock mass 1.

[0041] S2. Drive several anchor rods 5 into the excavated rock mass 2 to create a rock mass structure surface with several anchor rods 5 ends;

[0042] S3. Use construction machinery to pull out several anchor bolts 5;

[0043] S4, slag removal;

[0044] S5. Later-stage rock mass support.

[0045] When using this method to break up hard rock, the first step is to create an outline of the excavated rock mass, delineating the rock mass to be excavated. Then, a weakened structural surface is created along the outline, which will form cracks around the excavated rock mass. Next, several anchor bolts are driven into the excavated rock mass, with one end extending into the excavated rock mass and the other end remaining on the outside, forming a rock mass structural surface with several anchor bolt ends. The anchor bolts are then removed mechanically, with one end anchored to the inside of the excavated rock mass. Under the action of the cracks formed by the weakened structural surface along the outline, the excavated rock mass is broken at the cracks, thus achieving the breaking and removal of the hard rock. This construction process, using anchor bolt pulling, replaces the negative impacts of traditional drilling and blasting methods, such as ground noise, dust, and surface vibration, greatly reducing disturbance to the surrounding rock and minimizing the risk of isolated boulders and falling rocks.

[0046] This invention combines micro-blasting with non-blasting mechanical methods for excavating hard rock tunnels. Pre-splitting blasting is used to create the excavation outline and weaken the structural surface, improving excavation efficiency and reducing equipment costs associated with mechanical excavation. Non-blasting mechanical methods are used to pull out several anchor bolts 5 within the excavated rock mass 2, better controlling over- and under-excavation, resulting in a smoother and more precise excavation face. Furthermore, this method involves relatively simple equipment and has low construction risk.

[0047] Further optimization of the scheme involves the following steps in creating the weakened structural surface of the excavated rock mass outline in S1:

[0048] S101, Geological survey of rock stratigraphy;

[0049] S102, Create the outline of the excavated rock mass 1;

[0050] S103. Several boreholes are drilled along the outline of the excavated rock mass 1.

[0051] S104. The pre-splitting blasting of the borehole produces artificial rock mass cracks 3 of a certain depth, and the artificial rock mass cracks 3 are chemically corroded.

[0052] Further optimize the scheme. In S102, the range of the excavated rock mass outline 1 is set according to the single-cycle excavation advance and the length of the anchor rod 5. The single-cycle excavation advance and the length of the anchor rod 5 are compared to obtain the smaller value between the two. When the single-cycle excavation advance is less than the length of the anchor rod 5, the excavated rock mass outline 1 is 3cm to 6cm greater than the single-cycle excavation advance.

[0053] When the single-cycle excavation advance is greater than the length of anchor bolt 5, the excavated rock mass outline 1 is 3cm to 6cm longer than the length of anchor bolt 5.

[0054] This arrangement facilitates the removal of cracked rock blocks from the rock mass.

[0055] The single-cycle excavation advance is a given value. After selecting anchor bolt 5, its length is obtained by measuring anchor bolt 5.

[0056] Further optimization of the scheme: In S103, the drilling depth is the same as the depth of the single-cycle excavation advance.

[0057] Further optimization of the scheme: In S104, the borehole is set perpendicular to the wall of the excavated rock mass 2.

[0058] In a further optimized scheme, S104, a static expansion agent is used to chemically corrode the cracks in the artificial rock mass.

[0059] The boreholes are set perpendicular to the wall of the excavated rock mass 2, and the depth of the boreholes is the same as the depth of the single-cycle excavation advance. The boreholes are used for pre-splitting blasting, which will create artificial rock mass cracks 3 of a certain depth along the outline 1 of the excavated rock mass. Pre-splitting blasting has little impact on the preserved rock mass, which is conducive to the stability of the preserved rock mass, can reduce over-excavation and under-excavation, and save on project investment.

[0060] The static expansion agent is injected into the artificial rock mass crack 3 after hydration. The expansion stress will continue to increase, which will cause the artificial rock mass crack 3 to expand continuously, causing the excavated rock mass 2 to expand, crack and fall off, which can significantly improve the tunnel excavation efficiency.

[0061] Further optimization of the scheme: In S2, driving several anchor bolts into the excavated rock mass includes the following steps:

[0062] S201. Several anchor bolt holes 4 are set in the excavated rock mass 2, and the anchor bolt holes 4 are set perpendicular to the wall of the excavated rock mass 2.

[0063] S202. Drive the anchor bolt 5 into the anchor bolt drill hole 4;

[0064] S203. Grouting is performed on anchor bolt 5 to anchor anchor bolt 5 to the excavated rock mass 2.

[0065] like Figure 3 As shown, several anchor bolt holes 4 are arranged in a matrix on the wall of the excavated rock mass 2.

[0066] The diameter of the anchor bolt hole 4 should be set according to the diameter of the anchor bolt 5, specifically 2cm to 3cm larger than the length of the anchor bolt.

[0067] The number of anchor bolt holes 4 can be greater than the number of anchor bolts 5, or the number of anchor bolt holes 4 can correspond to the number of anchor bolts 5. When the number of anchor bolt holes 4 is greater than the number of anchor bolts 5, it can help improve excavation efficiency.

[0068] The appropriate number of anchor bolts 5 should be selected to form a regular track shape to prevent over-excavation and under-excavation. Small excavation equipment can be used to pull out the anchor bolts 5, which is suitable for the excavation of small and medium-sized tunnels. Of course, for large tunnels, large equipment can also be used for excavation to improve the efficiency of excavation.

[0069] Furthermore, the anchor bolt 5 includes a hollow rod body 503, one end of which is fixedly connected to a rubber head end 504, and the other end of the hollow rod body 503 is fitted with and slidably connected to a grout stop plug 502. The end of the hollow rod body 503 away from the rubber head end 504 is also threadedly connected to a nut 501.

[0070] The hollow rod 503 has an opening in the middle, which serves as a high-pressure ventilation channel and a grouting channel.

[0071] A hydraulic cementitious material with controllable setting time and high strength can be selected as the anchoring grout between the anchor rod and the rock mass.

[0072] In a further optimized scheme, in S2, a flammable cartridge is placed at one end of the anchor bolt 5 located within the excavated rock mass 2. The flammable cartridge is used to weaken the tensile strength of the rock mass at the end of the anchor bolt 5.

[0073] The chemical erosion cartridge only serves to chemically erode the rock mass, weakening its tensile strength. The cartridge's composition only needs to produce a chemical erosion effect on the rock mass. The cartridge is existing technology and will not be elaborated here.

[0074] In a further optimized scheme, in S3, several anchor bolts 5 are pulled out sequentially using a mechanical pulling method.

[0075] Several anchor bolts 5 are pulled out one by one. The order in which the anchor bolts 5 are pulled out can be from left to right or from top to bottom.

[0076] like Figure 2 The anchor bolts 5 are pulled out sequentially along the mechanical pulling direction 6 using a mechanical pulling method, completing a single excavation. For the excavation of small and medium-sized tunnels, small excavation equipment can be used to pull out the anchor bolts 5; for large tunnels, large equipment can also be used to improve excavation efficiency.

[0077] Furthermore, the material of the anchor bolt 5 can be selected as an ultra-high tensile strength material, such as 3.5-10Mpa carbon fiber or spider silk biomaterial, which greatly increases the volume of rock mass that a single anchor bolt 5 can pull out, and can be removed and reused later.

[0078] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0079] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for anchoring and pulling out sections of hard rock tunnels during excavation, characterized by: Includes the following steps: S1. Set the outline of the excavated rock mass (1), create a weakened structural surface along the outline of the excavated rock mass (1), and mark the part of the excavated rock mass (2) that needs to be removed; S2. Drive several anchor rods (5) into the part of the rock mass (2) to be excavated to form a weakened structural surface with several ends of the anchor rods (5); S3. Use construction machinery to pull out several of the anchor rods (5); S4, slag removal; S5. Later-stage rock mass support; The creation of the weakened structural surface of the excavated rock mass outline in S1 includes the following steps: S101, Geological survey of rock stratigraphy; S102. Create the outline of the excavated rock mass (1); S103. Drill several holes along the outline of the excavated rock mass (1); S104. The pre-splitting blasting of the borehole produces artificial rock mass cracks (3) of a certain depth, and the artificial rock mass cracks (3) are chemically corroded. In step S2, driving a plurality of anchor bolts into the excavated rock mass includes the following steps: S201. A number of anchor bolt holes (4) are set in the excavated rock mass (2), and the anchor bolt holes (4) are set perpendicular to the wall of the excavated rock mass (2); S202, drive the anchor rod (5) into the anchor rod drill hole (4); S203. Grout the anchor rod (5) to anchor the anchor rod (5) to the excavated rock mass (2); In S2, a cartridge is placed at one end of the anchor rod (5) located in the excavated rock mass (2), and the cartridge is used to weaken the tensile strength of the rock mass at the end of the anchor rod (5); In S3, several of the anchor rods (5) are pulled out sequentially by mechanical pulling.

2. The anchoring and pull-out construction method for the excavated section of a hard rock tunnel according to claim 1, characterized in that: In S102, the range of the excavated rock mass outline (1) is set according to the single-cycle excavation advance and the length of the anchor rod (5). The single-cycle excavation advance and the length of the anchor rod (5) are compared to obtain the smaller value between the two. When the single-cycle excavation advance is less than the length of the anchor rod (5), the excavated rock mass outline (1) is 3cm to 6cm greater than the single-cycle excavation advance. When the single-cycle excavation advance is greater than the length of the anchor rod (5), the excavated rock mass outline (1) is 3cm to 6cm longer than the length of the anchor rod (5).

3. The anchoring and pull-out construction method for the excavated section of a hard rock tunnel according to claim 2, characterized in that: In step S103, the depth of the borehole is the same as the depth of the single-cycle excavation advance.

4. The anchoring and pull-out construction method for the excavated section of a hard rock tunnel according to claim 1, characterized in that: In S103, the borehole is set perpendicular to the wall of the excavated rock mass (2).

5. The method for anchoring and pulling out the excavated section of a hard rock tunnel according to claim 1, characterized in that: In S104, the artificial rock mass cracks (3) are chemically corroded by a static expansion agent.

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