Rapid mechanical excavation device and construction method suitable for hard rock tunnel engineering

Abstract

The invention relates to the technical field of iron engineering, and provides a rapid mechanical excavation device and method suitable for hard rock tunnel engineering, the section of a tunnel is divided into an upper step area and a lower step area, and the upper step area and the lower step area are subdivided into three construction ranges A, B and C. The zone A adopts a diamond wire saw hydraulic drilling and cutting all-in-one machine to cut rocks; a crawler-type annular drilling machine is used for drilling in the area B, and then a hydraulic splitting rod is used for splitting a rock stratum; and the area C adopts a mine vertical disk saw and a horizontal disk saw for cutting, and then an excavator is used for crushing. The technology is suitable for hard rock strata, mechanical equipment is miniaturized, large vibration is avoided in the construction process, the influence on adjacent railways is small, and the working efficiency is high. And in the implementation case that the water conservancy tunnel passes through the combined high-speed rail roadbed, the construction influence is effectively reduced, and the construction speed is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of railway engineering, and in particular to a rapid mechanical excavation device and a construction method suitable for hard rock tunnel engineering. Background Art

[0002] In railway projects, in order to ensure the safety of railway structures and operations, blasting is not allowed in sections where the project crosses the railway or is close to the railway. Common non-blasting excavation measures include static crushing and mechanical crushing. The above solutions are inefficient when encountering high rock strength, which will affect the construction period of railway projects and increase the risk of railway operations and railway costs. Although the use of shield or TBM equipment can ensure the construction speed and effect, the cost is high and it is suitable for long tunnels. It is not economical for local sections involving railways and should not be used. Summary of the invention

[0003] In view of the shortcomings of the prior art, the present invention provides a rapid mechanical excavation device and method suitable for hard rock tunnel engineering. The diamond wire saw combined with the saw blade cutting technology can be applied to high-strength rocks. The mechanical equipment used is small in size and relatively economical, and is suitable for non-explosive excavation construction of tunnels in railway projects.

[0004] In order to solve the above technical problems, the specific technical solutions of the present invention are as follows:

[0005] In a first aspect, the present invention provides a rapid mechanical excavation device suitable for hard rock tunnel engineering, comprising:

[0006] Diamond wire saw hydraulic drilling and cutting machine, used in construction area A, cuts out rectangular rock blocks of 3x3m and 15-20m in depth, and performs cutting operations through the operating control panel;

[0007] Crawler-type circular drilling rig is used to drill holes with a diameter of 100-120mm and a depth of 3 meters in the construction area B. It moves to the designated position for drilling operations through the crawler walking mechanism;

[0008] The segmented hydraulic splitting rod is used to be inserted into the hole drilled by the crawler-type circular drill to split the rock layer and form an upper step working surface. It is inserted into the hole in the order of top first and side later, and the splitting force is provided by the hydraulic system;

[0009] Mining vertical circular saw, used for C-zone facade cutting, each cutting depth is 1.5 meters, fixed installation or movable installation, cutting operation is performed through the operation control panel;

[0010] The rope saw machine is used to cut the bottom surface after the vertical circular saw in the mine completes the vertical cutting, in preparation for the subsequent excavator crushing. The cutting operation is performed through the operating control panel.

[0011] Excavators are used to break up cut rock blocks and to clear slag, using bucket attachments for breaking and clearing operations.

[0012] Horizontal circular saw is used for horizontal surface cutting in zone C. Each cutting depth is to the edge line. Horizontal cutting operation is performed through the operating control panel.

[0013] In a second aspect, the present invention provides a rapid mechanical excavation method suitable for hard rock tunnel engineering, comprising:

[0014] Step 1: Divide the tunnel section into an upper step area and a lower step area, and divide the construction into construction scope A, construction scope B and construction scope C. Construction scope A and construction scope B are located in the upper step area, and construction scope C is located in the lower step area;

[0015] Step 2: A diamond wire saw hydraulic drilling and cutting machine is used to cut out rectangular blocks of 3x3m and 15-20m in depth in construction area A. The cut rock blocks can be dragged out and broken in sections;

[0016] Step 3: A crawler-type circular drilling rig is used in the construction area B. The crawler-type circular drilling rig drills holes at preset intervals. The diameter of the holes ranges from 100 to 120 mm, and the depth of the holes is 3 meters.

[0017] Step 4: Use a segmented hydraulic splitting rod to insert into the drilled hole in the order of top first and side later. The segmented hydraulic splitting rod has a diameter of 100 mm, splits the rock layer, forms an upper step working surface, completes 3 meters of excavation in one operation, and performs the operation cycle until it is advanced to the square hole depth;

[0018] Step 5: Cut the vertical surface of area C with a mining vertical circular saw. The cutting depth is 1.5 meters each time, and the operation length is the length of the upper step working surface. After the vertical surface cutting is completed, the bottom surface is cut with a rope saw, crushed by an excavator, and then slag is removed;

[0019] Step 6: Cut the horizontal surface of area C with a horizontal circular saw. Cut to the edge each time, and the working length is the length of the upper half step working surface.

[0020] Step 7: Use ordinary wire saw to cut or excavator to crush to the edge line, and the first layer of area C is completed;

[0021] Step 8, repeat steps 5 to 7 to complete the construction of the lower step work area in two layers.

[0022] Furthermore, in the rapid mechanical excavation method applicable to hard rock tunnel engineering of the present invention, step 2 comprises:

[0023] Use diamond wire saw hydraulic drilling and cutting machine: within the construction scope of A, use diamond wire saw hydraulic drilling and cutting machine for cutting;

[0024] The diamond wire saw hydraulic drilling and cutting machine cuts out rectangular blocks of 3x3m and 15-20m in depth;

[0025] The cut rock pieces are hauled out in sections and broken up.

[0026] Furthermore, in the rapid mechanical excavation method applicable to hard rock tunnel engineering of the present invention, step 3 comprises:

[0027] Using crawler ring drilling rig:

[0028] The equipment used is a crawler-type circular drilling rig in the construction area B;

[0029] The drilling operation drills holes with a diameter of 100-120mm and a depth of 3 meters according to the designed spacing.

[0030] Furthermore, in the rapid mechanical excavation method applicable to hard rock tunnel engineering of the present invention, step 4 comprises:

[0031] The specific steps of step 4 are:

[0032] Use a segmented hydraulic splitting rod to insert it into the hole in the order of top first and side later, split the rock layer and form an upper step working surface. 3 meters of excavation can be completed in one operation, and the operation cycle is carried out until it reaches the depth of the square hole.

[0033] Furthermore, in the rapid mechanical excavation method applicable to hard rock tunnel engineering of the present invention, step 5 comprises:

[0034] Specific steps for cutting the facade of area C:

[0035] A mining vertical circular saw is used for cutting, with each cutting depth of 1.5 meters and the operating length being the length of the upper half step working surface;

[0036] After the facade cutting is completed, use the wire saw machine to cut the bottom surface;

[0037] Use an excavator to crush the cut rock blocks;

[0038] After crushing, slag removal work is carried out to clear the broken rock pieces and other debris from the construction site.

[0039] Furthermore, in the rapid mechanical excavation method applicable to hard rock tunnel engineering of the present invention, step 6 comprises:

[0040] Specific steps for horizontal cutting of area C:

[0041] The equipment used is a horizontal circular saw, the cutting depth is from the cutting depth to the edge line each time, and the operating length is the length of the upper half step working surface.

[0042] Furthermore, in the rapid mechanical excavation method applicable to hard rock tunnel engineering of the present invention, step 7 comprises:

[0043] Specific steps to complete the construction of the first floor of Area C:

[0044] After the horizontal surface cutting of Zone C is completed, ordinary wire saws are used for cutting, or excavators are used for crushing. The cutting or crushing needs to reach the edge of the tunnel.

[0045] Beneficial effects of the present invention:

[0046] This method is suitable for non-explosive tunneling projects, especially for hard rock formations. The mechanical equipment used in the construction, such as diamond wire saw hydraulic drilling and cutting machine, crawler ring drill, mining vertical circular saw, etc., are all small equipment, which are convenient to enter and exit, have a large working space, and are safe for personnel to work. The construction process does not produce large vibrations, has little impact on the adjacent railway, and can better ensure the safety of railway operations. Compared with commonly used static cracking and static crushing methods, this method has obvious advantages in work efficiency under high-strength surrounding rock conditions, and the daily footage can reach 2m. This method uses small equipment compared to large equipment methods such as TBM, which saves investment. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solution of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, for ordinary technicians in this field, other drawings can be obtained based on the drawings without paying any creative labor.

[0048] Figure 1 A schematic diagram of a cross-sectional division diagram provided for an embodiment of the present invention.

[0049] Figure 2 A schematic diagram of a diamond wire saw hydraulic drilling rig provided in an embodiment of the present invention.

[0050] Figure 3 Schematic diagram of a diamond wire saw cutting a rectangular block provided by an embodiment of the present invention.

[0051] Figure 4 A schematic diagram of a drilling hole for rock splitting provided in an embodiment of the present invention.

[0052] Figure 5 A schematic diagram of a step-up construction model provided in an embodiment of the present invention.

[0053] Figure 6 A schematic diagram of a vertical circular saw for vertically cutting a lower step in a mine provided in an embodiment of the present invention.

[0054] Figure 7A schematic diagram of a step-down construction model provided in an embodiment of the present invention.

[0055] Figure 8 Schematic diagram of a horizontal circular saw provided in an embodiment of the present invention cutting a step down to a designed width.

[0056] Fig. 9 A schematic diagram of the final cutting profile of a tunnel provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The technical solutions provided by the embodiments of the present invention are described in detail below in conjunction with the drawings.

[0058] In order to better understand the purpose of the present invention, the present invention is described in further detail below.

[0059] In a first aspect, the present invention provides a rapid mechanical excavation device suitable for hard rock tunnel engineering, comprising:

[0060] Diamond wire saw hydraulic drilling and cutting machine, used in construction area A, cuts out rectangular rock blocks of 3x3m and 15-20m in depth, and performs cutting operations through the operating control panel;

[0061] Crawler-type circular drilling rig is used to drill holes with a diameter of 100-120mm and a depth of 3 meters in the construction area B. It moves to the designated position for drilling operations through the crawler walking mechanism;

[0062] The segmented hydraulic splitting rod is used to be inserted into the hole drilled by the crawler-type circular drill to split the rock layer and form an upper step working surface. It is inserted into the hole in the order of top first and side later, and the splitting force is provided by the hydraulic system;

[0063] Mining vertical circular saw, used for C-zone facade cutting, each cutting depth is 1.5 meters, fixed installation or movable installation, cutting operation is performed through the operation control panel;

[0064] The rope saw machine is used to cut the bottom surface after the vertical circular saw in the mine completes the vertical cutting, in preparation for the subsequent excavator crushing. The cutting operation is performed through the operating control panel.

[0065] Excavators are used to break up cut rock blocks and to clear slag, using bucket attachments for breaking and clearing operations.

[0066] Horizontal circular saw is used for horizontal surface cutting in zone C. Each cutting depth is to the edge line. Horizontal cutting operation is performed through the operating control panel.

[0067] The connection and installation relationship between equipment and devices;

[0068] The equipment devices in the present invention are all independent equipment and do not require complicated connection and installation relationships.

[0069] Equipment is mainly connected logically through construction processes and procedures rather than physically.

[0070] Each equipment is arranged and operated in the designated position and sequence at the construction site.

[0071] The function of the equipment;

[0072] Diamond wire saw hydraulic drilling and cutting machine: efficient cutting of rock blocks, providing a basis for subsequent construction.

[0073] Crawler-type circular drilling rig: Drilling prepares for the subsequent splitting of the rock formation, ensuring the smooth progress of the construction process.

[0074] Segmented hydraulic splitting rod: splits the rock layer, forms a working surface, and improves construction efficiency.

[0075] Mining vertical circular saw and wire saw machine: complete the cutting work of the vertical and bottom surfaces of area C, and prepare for subsequent excavator crushing.

[0076] Excavator: crush the cut rock blocks, clean up the construction site, and ensure construction safety and progress.

[0077] Horizontal circular saw: completes the cutting work on the horizontal surface of area C, further improving construction accuracy and efficiency.

[0078] Logical relationships between equipment;

[0079] Construction process: Construction is carried out in the order of "cutting in construction range A → drilling in construction range B → splitting rock strata → vertical surface cutting in area C → bottom surface cutting → crushing by excavator → horizontal surface cutting".

[0080] Process connection: After each equipment device completes its specific process, the next equipment device can proceed to its process. For example, the crawler ring drill can only perform drilling operations after the diamond wire saw hydraulic drilling and cutting machine completes cutting; the mining vertical circular saw can only perform vertical surface cutting after the rock layer is split to form an operating surface, etc.

[0081] Collaborative work: Although each device is an independent device, they need to work together during the construction process to ensure a smooth and efficient construction process. For example, the excavator needs to crush and remove slag in time after the vertical circular saw and wire saw machine in the mine completes the cutting, so that the subsequent processes can proceed smoothly.

[0082] See also Figures 1 to 9 In a second aspect, the present invention provides a rapid mechanical excavation method suitable for hard rock tunnel engineering, comprising:

[0083] Step 1: Divide the tunnel section into two steps, upper and lower, and divide the work into three construction areas: A, B, and C.

[0084] Step 2: A diamond wire saw hydraulic drilling and cutting machine is used to cut out rectangular blocks of 3x3m and 15-20m in depth in construction area A. The cut rock blocks can be dragged out in sections and broken.

[0085] Step 3: Use a crawler-type circular drill rig in construction scope B to drill holes with a diameter of 100-120mm and a depth of 3 meters at the locations shown in the figure according to the designed spacing.

[0086] Step 4: Use a segmented hydraulic splitting rod (100mm in diameter) to insert into the drilled hole in the order of top first and side later, split the rock layer, form an upper step working surface, and complete 3 meters of excavation in one operation. The operation cycle is repeated until the square hole depth is reached.

[0087] Step 5: Cut the vertical surface of area C (lower step area) with a vertical circular saw. The cutting depth is 1.5 meters each time and the operation length is the length of the upper step working surface. After the vertical surface cutting is completed, the bottom surface is cut with a rope saw, and the excavator is used for crushing and slag removal.

[0088] Step 6, horizontal surface cutting of area C (lower step area) is carried out using a horizontal circular saw. The cutting depth each time is to the edge line, and the working length is the length of the upper step working surface.

[0089] Step 7: Use ordinary wire saw to cut or excavator to crush to the edge line, and the first layer of area C is completed.

[0090] Repeat steps 5 to 7 to complete the construction of the lower step work area in two layers.

[0091] The water conservancy tunnel passes under the Hefu high-speed railway foundation, with a clear distance of about 60m. According to the pre-engineering design, non-explosive excavation is used within the intersection range of 184m. The technical solution of the present invention is used to reduce the impact of construction on the railway and speed up the construction speed. After many aspects of investigation and comparison, the diamond wire saw combined with saw blade cutting solution is finally determined.

[0092] The specific embodiments of the technical solution of the present invention in actual use are as follows:

[0093] Step 1: Divide the tunnel section into the upper step area and the lower step area, and divide the work into construction scope A, construction scope B and construction scope C. Construction scope A and construction scope B are located in the upper step area, and construction scope C is located in the lower step area.

[0094] Step 2: A diamond wire saw hydraulic drilling and cutting machine is used to cut out rectangular blocks of 3x3m and 15-20m in depth in the construction area. The cut rock blocks can be dragged out in sections and broken.

[0095] Step 3: Use a crawler-type circular drilling rig to drill holes at preset intervals in the construction area B. The diameter of the holes ranges from 100-120mm and the depth is 3 meters.

[0096] Step 4: Use a segmented hydraulic splitting rod (100mm in diameter) to insert into the drilled hole in the order of top first and side later, splitting the rock layer to form an upper step working surface. One operation completes 3 meters of excavation, and then the operation cycle is carried out until it reaches the square hole depth.

[0097] Step 5: Cut the vertical surface of area C with a mining vertical circular saw, with a cutting depth of 1.5 meters each time and the working length equal to the length of the upper step working surface. After the vertical surface cutting is completed, a rope saw is used to cut the bottom surface, and then an excavator is used for crushing and slag removal.

[0098] Step 6: Cut the horizontal surface of area C using a horizontal circular saw. Cut to the edge each time, and the working length is the length of the upper step working surface.

[0099] Step 7: Use ordinary wire saw to cut or excavator to crush to the edge line, and the first layer of area C is completed.

[0100] Step 8: Repeat the process from step 5 to step 7 to complete the construction of the lower step work area in two layers.

[0101] In addition, a specific application example is given: in the project of a water conservancy tunnel under the Hefu high-speed railway foundation, according to the pre-engineering design, non-explosive excavation is used within the intersection range of 184m. In order to reduce the impact of construction on the railway and speed up the construction speed, the technical solution of the present invention, that is, the solution of diamond wire saw combined with saw blade cutting, was finally determined.

[0102] The technical solution of the present invention realizes the non-explosive excavation construction of tunnels in railway projects through the following steps:

[0103] Construction area division: The tunnel section is divided into the upper step area and the lower step area, which are further subdivided into three construction areas: A, B, and C. This division method helps to optimize the construction process and improve the overall construction efficiency.

[0104] Cutting in construction range A: A diamond wire saw hydraulic drilling and cutting machine is used to cut out rectangular blocks of 3x3m and 15-20m in depth in construction range A. This cutting method is particularly suitable for high-strength rocks and can cut out rock blocks efficiently and accurately.

[0105] Drilling in Construction Area B: In Construction Area B, a crawler-type circular drill was used to drill holes with a diameter of 100-120mm and a depth of 3 meters at preset intervals. These holes were prepared for the subsequent splitting of the rock formation to ensure the smooth progress of the construction process.

[0106] Rock splitting: Use segmented hydraulic splitting rods to insert into the drilled hole in the order of top first and side later to split the rock. This step can form a step-up working surface, and each operation can complete 3 meters of excavation.

[0107] Vertical cutting of area C: vertical circular saws are used for vertical cutting, with a cutting depth of 1.5 meters each time, and the length of the operation is the length of the upper half of the step working surface. After the vertical cutting is completed, the bottom surface is cut with a rope saw, followed by excavator crushing and slag removal. This step ensures the efficiency and safety of the construction of area C.

[0108] Horizontal surface cutting of area C: Use a horizontal circular saw to cut the horizontal surface, with each cutting depth reaching the edge and the operation length being the length of the upper half step working surface. This step further improves the accuracy and efficiency of the construction of area C.

[0109] The first layer of construction in Zone C is completed: After the horizontal plane of Zone C is cut, it is cut with a common wire saw or crushed with an excavator until it reaches the edge of the tunnel. This step marks the successful completion of the first layer of construction in Zone C.

[0110] Repeat the construction process: By repeating the process from step 5 to step 7, the construction of the lower half step work area is completed in two layers. This cyclic construction method ensures the continuity of the entire tunnel excavation process.

[0111] In summary, the technical solution of the present invention achieves high efficiency, safety and precision in non-explosive tunnel excavation through a series of carefully designed steps, and is particularly suitable for excavation of hard rock strata in railway-related projects.

Claims

1. A rapid mechanical excavation device suitable for hard rock tunnel engineering, characterized in that: include: Diamond wire saw hydraulic drilling and cutting machine, used in construction area A, cuts out rectangular rock blocks of 3x3m and 15-20m in depth, and performs cutting operations through the operating control panel; Crawler-type circular drilling rig is used to drill holes with a diameter of 100-120mm and a depth of 3 meters in the construction area B. It moves to the designated position for drilling operations through the crawler walking mechanism; The segmented hydraulic splitting rod is used to be inserted into the hole drilled by the crawler-type circular drill to split the rock layer and form an upper step working surface. It is inserted into the hole in the order of top first and side later, and the splitting force is provided by the hydraulic system; Mining vertical circular saw, used for C-zone facade cutting, each cutting depth is 1.5 meters, fixed installation or movable installation, cutting operation is performed through the operation control panel; The rope saw machine is used to cut the bottom surface after the vertical circular saw in the mine has completed the vertical cutting, in preparation for the subsequent excavator crushing, and the cutting operation is performed through the operating control panel; Excavators are used to break up the cut rock blocks and to clear the slag, using bucket attachments to perform the breaking and clearing operations; Horizontal circular saw is used for horizontal surface cutting in zone C. Each cutting depth is to the edge line. Horizontal cutting operation is performed through the operating control panel.

2. A rapid mechanical excavation method suitable for hard rock tunnel engineering, applied to the rapid mechanical excavation device suitable for hard rock tunnel engineering as claimed in claim 1, characterized in that: include: Step 1: Divide the tunnel section into an upper step area and a lower step area, and divide the construction into construction scope A, construction scope B and construction scope C. Construction scope A and construction scope B are located in the upper step area, and construction scope C is located in the lower step area; Step 2: A diamond wire saw hydraulic drilling and cutting machine is used to cut out rectangular blocks of 3x3m and 15-20m in depth in construction area A. The cut rock blocks can be dragged out and broken in sections; Step 3: A crawler-type circular drilling rig is used in the construction area B. The crawler-type circular drilling rig drills holes at preset intervals. The diameter of the holes ranges from 100 to 120 mm, and the depth of the holes is 3 meters. Step 4: Use a segmented hydraulic splitting rod to insert into the drilled hole in the order of top first and side later. The segmented hydraulic splitting rod has a diameter of 100 mm, splits the rock layer, forms an upper step working surface, completes 3 meters of excavation in one operation, and performs the operation cycle until it is advanced to the square hole depth; Step 5: Cut the vertical surface of area C with a mining vertical circular saw. The cutting depth is 1.5 meters each time, and the operation length is the length of the upper step working surface. After the vertical surface cutting is completed, the bottom surface is cut with a rope saw, crushed by an excavator, and then slag is removed; Step 6: Cut the horizontal surface of area C with a horizontal circular saw. Cut to the edge each time, and the working length is the length of the upper half step working surface. Step 7: Use ordinary wire saw to cut or excavator to crush to the edge line, and the first layer of area C is completed; Step 8, repeat steps 5 to 7 to complete the construction of the lower step work area in two layers.

3. The rapid mechanical excavation method for hard rock tunnel engineering according to claim 2, characterized in that: The step 2 comprises: Use diamond wire saw hydraulic drilling and cutting machine: within the construction scope of A, use diamond wire saw hydraulic drilling and cutting machine for cutting; The diamond wire saw hydraulic drilling and cutting machine cuts out rectangular blocks of 3x3m and 15-20m in depth; The cut rock pieces are hauled out in sections and broken up.

4. The rapid mechanical excavation method for hard rock tunnel engineering according to claim 2, characterized in that: The step 3 comprises: Using crawler ring drilling rig: The equipment used is a crawler-type circular drilling rig in the construction area B; The drilling operation drills holes with a diameter of 100-120mm and a depth of 3 meters according to the designed spacing.

5. The rapid mechanical excavation method for hard rock tunnel engineering as claimed in claim 2, characterized in that: The step 4 comprises: The specific steps of step 4 are: Use a segmented hydraulic splitting rod to insert it into the hole in the order of top first and side later, split the rock layer and form an upper step working surface. 3 meters of excavation can be completed in one operation, and the operation cycle is carried out until it reaches the depth of the square hole.

6. The rapid mechanical excavation method for hard rock tunnel engineering as claimed in claim 2, characterized in that: The step 5 comprises: Specific steps for cutting the facade of area C: A mining vertical circular saw is used for cutting, with each cutting depth of 1.5 meters and the operating length being the length of the upper half step working surface; After the facade cutting is completed, use the wire saw machine to cut the bottom surface; Use an excavator to crush the cut rock blocks; After crushing, slag removal work is carried out to clear the broken rock pieces and other debris from the construction site.

7. The rapid mechanical excavation method for hard rock tunnel engineering according to claim 2, characterized in that: The step 6 comprises: Specific steps for horizontal cutting of area C: The equipment used is a horizontal circular saw, the cutting depth is from the cutting depth to the edge line each time, and the operating length is the length of the upper half step working surface.

8. The rapid mechanical excavation method for hard rock tunnel engineering as claimed in claim 2, characterized in that: The step 7 comprises: Specific steps to complete the construction of the first floor of Area C: After the horizontal surface cutting of zone C is completed, it is cut by a common wire saw or crushed by an excavator. The cutting or crushing needs to reach the edge of the tunnel.

Images