A large-span multi-arch hard rock tunnel mechanical excavation construction method

Abstract

The application discloses a large-span continuous-arch hard rock tunnel mechanical tunneling construction method, which comprises the following steps: step one, pre-construction planning; step two, central pilot hole construction; step three, upper bench construction; step four, lower bench construction; and step five, inverted arch construction; wherein in the step one, the whole section of the large-span continuous-arch tunnel is divided into seven parts, i.e., a central pilot hole, a left hole upper bench, a left hole lower bench, a left hole inverted arch, a right hole upper bench, a right hole lower bench and a right hole inverted arch, the central pilot hole, the left hole upper bench and the right hole upper bench are excavated by using a cantilever tunneling machine, and the left hole lower bench, the left hole inverted arch, the right hole lower bench and the right hole inverted arch are excavated by using a hydraulic breaking hammer; the application adopts a tunneling mode of synchronous mechanical excavation and slag removal, replaces a traditional tunneling mode of step-by-step drilling, blasting, ventilation and slag removal, simplifies an operation process, improves operation efficiency and has small disturbance to surrounding rocks.

Description

Technical Field

[0001] This invention relates to the field of construction technology for large-span continuous arch tunnels, specifically a mechanical excavation construction method for large-span continuous arch hard rock tunnels. Background Technology

[0002] A twin-arch tunnel is a double-tunnel structure consisting of two tunnels connected by a shared central wall. It is a promising new type of tunnel structure. Arch tunnels have large spans, high space utilization, smooth alignment, and require less land for approach lines. They offer advantages over separate tunnels in terms of both horizontal alignment and portal location selection, especially in solving the difficulties associated with constructing separate tunnels in complex terrain. This makes them a commonly used large-span structural form for tunnel construction under specific conditions.

[0003] However, in the current construction of urban mountain tunnels, due to the dense urban population and buildings, the adverse effects of traditional drilling and blasting construction, such as noise and vibration, are becoming increasingly unacceptable. If there are sensitive buildings such as subways, dense building complexes, or important national defense buildings nearby, drilling and blasting construction also requires approval from the relevant authorities. The approval process is difficult, with many restrictions on construction operations, long workflows, and low efficiency, making it difficult to meet the requirements of safe and rapid construction. In addition, drilling and blasting construction often results in over-excavation and under-excavation, leading to an uneven and rounded tunnel profile, localized stress concentration, and poor tunnel profile shaping. Furthermore, the additional over-excavation and under-excavation also increases the amount of concrete spraying required for subsequent construction, raising construction costs. Summary of the Invention

[0004] The purpose of this invention is to provide a mechanical excavation method for large-span continuous arch hard rock tunnels to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a mechanical excavation construction method for a large-span continuous arch hard rock tunnel, comprising the following steps: Step 1, pre-construction planning; Step 2, construction of the pilot tunnel; Step 3, construction of the upper bench; Step 4, construction of the lower bench; Step 5, construction of the invert arch;

[0006] In step one above, the entire cross-section of the large-span arch tunnel is divided into seven parts: the central pilot tunnel, the upper bench of the left tunnel, the lower bench of the left tunnel, the invert of the left tunnel, the upper bench of the right tunnel, the lower bench of the right tunnel, and the invert of the right tunnel. The central pilot tunnel, the upper bench of the left tunnel, and the upper bench of the right tunnel are excavated using a cantilever tunneling machine, while the lower bench of the left tunnel, the invert of the left tunnel, the lower bench of the right tunnel, and the invert of the right tunnel are excavated using a hydraulic breaker.

[0007] In step two above, according to the construction drawings, the construction position of the central tunnel is determined by measuring instruments. The cantilever tunneling machine is then moved to the tunnel face to cut and excavate in front. A transport machine is connected to the rear to lift and transport the excavated material, which is then placed into a truck. The truck then passes through the support trolley to discharge the material outside the tunnel. After the excavation reaches the preset excavation depth, the excavation face is repaired and leveled, and timely measurement and verification are carried out. Any under-excavated parts are repaired until the designed excavation outline is reached. Then, the machine is operated to retreat, and the support trolley is lifted to the tunnel face for initial support. After the support is completed, one cycle of operation is finished. This cycle of operation is then repeated until the central tunnel is completed. Then, the central partition wall is constructed, and the concrete of the central partition wall reaches the design strength. The construction of the central tunnel is then completed.

[0008] In step three above, the upper steps of the left and right tunnels are divided into a sequential construction order, designated as the first and second main tunnels respectively, and constructed sequentially. The gap between the surrounding rock and the central partition wall of the second main tunnel is then backfilled with earth and rock. Next, construction begins on the first main tunnel, with the cantilever tunneling machine positioned at the tunnel face to cut and excavate. Muck is then transported by a transport machine or excavator and removed by trucks. After reaching the predetermined excavation depth, the excavation face is leveled and measured for verification. The under-excavated parts are trimmed until the designed excavation outline is reached. Then the machine is moved back and the support trolley is lifted to the working face for initial support. After the support is completed, one cycle of operation is completed. Then the cycle of operation is repeated until the main tunnel is completed. Before the main tunnel is completed, after the distance between the working face of the main tunnel and the working face of the secondary main tunnel reaches the design standard, the backfill soil and rock are cleared and transported out, and the construction of the secondary main tunnel is carried out in coordination. The construction process is the same as that of the main tunnel until the secondary main tunnel is completed and the upper step construction is completed.

[0009] In step four above, construction is carried out simultaneously on the left and right sides. The excavation edge lines of the left tunnel invert and the right tunnel invert are measured and marked out respectively. Based on these limits, an excavator equipped with a hydraulic breaker is used to break and excavate in front, and the excavator is used in conjunction with a dump truck to remove the slag. After the excavation reaches the preset excavation depth, the excavation face is repaired and leveled, and timely measurement and verification are carried out. Any under-excavated parts are repaired until the designed excavation outline is reached. Then, the machine is operated to retreat, and the support trolley is lifted to the working face for initial support. After the support is completed, one cycle of operation is completed. Then, the cycle of operation is repeated until the lower bench of the left tunnel and the lower bench of the right tunnel are connected and the lower bench construction is completed.

[0010] In step five above, based on the tunnel monitoring and measurement results, once the deformation values ​​of the left and right lower steps of the tunnel are within the design allowable range and remain stable, construction on the left and right sides proceeds simultaneously. After surveying and setting out, an excavator equipped with a hydraulic breaker is used to break and excavate in front, and the excavator is used in conjunction with dump trucks to remove the slag. Then, after excavating to the preset excavation depth, the excavation face is repaired and leveled, and timely measurement and verification are carried out. Any under-excavated parts are repaired until the designed excavation outline is reached. Then, the machine is operated to retreat, and the support trolley is lifted to the working face for initial support. After the support is completed, one cycle of operation is finished. This cycle of operation is then repeated until the left and right invert arches are connected. Once the invert arch construction is completed, the tunnel construction is finished.

[0011] Preferably, in step two, the preset excavation advance of the cantilever tunneling machine is limited to 1 to 2 cutting head lengths.

[0012] Preferably, in step two, the tunneling process of the cantilever tunneling machine is as follows: after the cantilever tunneling machine is in place, a groove is first cut horizontally from the bottom of the tunnel face at high speed. The tunneling machine is then moved forward and placed in place again. After being in place, the cutting head performs cyclic cutting from top to bottom and left to right, excavating from the bottom to the arch. After completion, a second trimming is performed at low speed to accurately adjust the cross-section to meet the requirements of the cross-section size.

[0013] Preferably, in step two, the cutting method of the cantilever tunneling machine is to start cutting from the bottom and then cut the upper part step by step according to the S-shaped or Z-shaped left-right circular upward cutting route. When using a right-hand rotating cutting head to cut hard rock, the cutting starts from the bottom from right to left and then proceeds from left to right and from bottom to top or from right to left and from top to bottom. If the rock has high joint development, the cutting method of the cantilever tunneling machine is to cut from the direction of the rock joints.

[0014] Preferably, in step three, the staggered distance between the face of the first main tunnel and the face of the second main tunnel is 30 meters.

[0015] Preferably, in step four, the preset excavation advance of the excavator equipped with a hydraulic breaker is limited to 1 to 2 times the length of the breaker.

[0016] Preferably, in step five, the excavation process of the excavator equipped with a hydraulic breaker is as follows: the excavator operates at the bottom of the completed tunnel, the hydraulic breaker is kept vertical, and the excavation is carried out from top to bottom. When hard rocks are encountered, the angle between the excavator's boom and the hydraulic breaker is changed, and the rocks are broken from top to bottom, left to right in sequence. Each direction is hit 2 to 3 times, each time for 2 to 4 seconds, to break the hard rocks.

[0017] Compared with existing technologies, the beneficial effects of this invention are as follows: This mechanical tunneling construction method for large-span continuous arch hard rock tunnels applies the combined mechanical tunneling technology of cantilever tunneling machines and hydraulic breakers to the construction of large-span continuous arch tunnels in sensitive urban areas, innovating tunneling operation technology. Mechanical tunneling causes less disturbance to the surrounding rock, which is beneficial to the stability of the surrounding rock and the safety of tunnel construction and surrounding vibration-sensitive buildings. The simultaneous operation of mechanical excavation and muck removal replaces the traditional step-by-step operation of drilling, blasting, ventilation, and muck removal, simplifying the operation process and improving efficiency. The innovative application of the combined tunneling technology of cantilever tunneling machines and hydraulic breakers allows for horizontal excavation of the upper steps using the cantilever tunneling machine during segmented tunnel excavation. The method involves using hydraulic breakers to vertically excavate and break rocks on the free face formed by the upper step, creating two or more parallel working faces. This improves the mechanization of tunnel construction, increases efficiency, significantly reduces the number of workers, enhances safety, and prevents tunnel accidents involving multiple injuries. The cutting head of the cantilever tunnel boring machine can adapt well to changes in the strength of the surrounding rock and the requirements of contour excavation, ensuring the smoothness of the tunnel's contour and avoiding over-excavation and under-excavation that often occur in blasting excavation. The excavated contour is smooth and rounded, avoiding local stress concentration and achieving good tunnel contour shaping. It also reduces over-excavation and under-excavation, saving on subsequent concrete spraying and effectively reducing construction costs. Attached Figure Description

[0018] Figure 1 This is a flowchart of the method of the present invention;

[0019] Figure 2 This is a diagram illustrating the tunneling sequence of the present invention. Detailed Implementation

[0020] 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.

[0021] Please see Figure 1-2 The present invention provides an embodiment of a mechanical tunneling construction method for a large-span continuous arch hard rock tunnel, comprising the following steps: Step 1, pre-construction planning; Step 2, construction of the pilot tunnel; Step 3, construction of the upper bench; Step 4, construction of the lower bench; and Step 5, construction of the invert arch.

[0022] In step one above, the entire cross-section of the large-span arch tunnel is divided into seven parts: the central pilot tunnel, the upper bench of the left tunnel, the lower bench of the left tunnel, the invert of the left tunnel, the upper bench of the right tunnel, the lower bench of the right tunnel, and the invert of the right tunnel. The central pilot tunnel, the upper bench of the left tunnel, and the upper bench of the right tunnel are excavated using a cantilever tunneling machine, while the lower bench of the left tunnel, the invert of the left tunnel, the lower bench of the right tunnel, and the invert of the right tunnel are excavated using a hydraulic breaker.

[0023] In step two above, the construction location of the central tunnel is determined using surveying instruments according to the construction drawings. The cantilever tunneling machine is then moved to the tunnel face to cut and excavate. A transport machine is connected to the rear to lift and transport the excavated material, which is then placed into a truck. The truck then passes through the support trolley to discharge the material outside the tunnel. After the cantilever tunneling machine is in place, a groove is first cut horizontally from the bottom of the tunnel face at high speed. The machine is then moved forward and positioned again. After positioning, the cutting head performs a top-down, left-right cyclic cutting, excavating from the bottom to the arch. After completion, a second trimming is performed at low speed to accurately achieve the designed cross-section and meet the required cross-sectional dimensions. The cantilever tunneling machine starts cutting from the bottom and then cuts the upper part step by step according to an S-shaped or Z-shaped left-right cyclic upward cutting route. A right-hand rotating cutting head is used to cut the hard... For rock, the cutting begins from the bottom, moving from right to left. Then, the cutting proceeds from left to right and from bottom to top, or from right to left and from top to bottom. If the rock has high joint development, the cutting is done gradually from the direction of the rock joints. The cutting method of the cantilever tunneling machine starts from the bottom. The preset excavation advance of the cantilever tunneling machine is limited to 1-2 cutting head lengths. After the preset excavation advance is reached, the excavation face is repaired and leveled, and timely measurement and verification are carried out. Any under-excavated parts are repaired until the designed excavation outline is reached. Then, the machine is reversed and the support trolley is lifted to the working face for initial support. After the support is completed, one cycle of operation is completed. This cycle of operation is repeated until the central tunnel is completed. Then, the central partition wall is constructed and the concrete of the central partition wall reaches the design strength. The construction of the central tunnel is then completed.

[0024] In step three above, the upper steps of the left and right tunnels are divided into a sequential construction order, designated as the first and second main tunnels respectively, and constructed sequentially. The gap between the surrounding rock and the central partition wall of the second main tunnel is then backfilled with earth and rock. Next, construction begins on the first main tunnel, with the cantilever tunneling machine positioned at the tunnel face to cut and excavate. Muck is then transported by a transport machine or excavator and removed by trucks. After reaching the predetermined excavation depth, the excavation face is leveled and measured for verification. The under-excavated section is trimmed until the designed excavation outline is reached. Then, the machine is moved back and the support trolley is lifted to the working face for initial support. Once the support is completed, one cycle of operation is finished. This cycle of operation is repeated until the main tunnel is completed. Before the main tunnel is completed, the backfill soil and rock are cleared and transported out after the distance between the working faces of the main tunnel and the secondary main tunnel reaches the design standard of 30 meters. The construction of the secondary main tunnel is carried out in coordination with the construction of the secondary main tunnel. The construction process is the same as that of the main tunnel until the secondary main tunnel is completed and the upper step construction is finished.

[0025] In step four above, construction proceeds simultaneously on the left and right sides. The excavation lines for the left and right tunnel inverts are measured and marked out. Using these lines as boundaries, excavators equipped with hydraulic breakers are used to break and excavate from the front, with dump trucks assisting in muck removal. The excavators, equipped with hydraulic breakers, operate at the bottom of the completed tunnel, keeping the hydraulic breakers vertical. Breaking and excavating proceeds from top to bottom. When encountering hard rock, the angles between the excavator's boom and the hydraulic breakers are adjusted, breaking the rock sequentially from top to bottom, left to right. Repeat the hammering 2-3 times in each direction, each time for 2-4 seconds, to break the hard rock. The preset excavation advance of the excavator equipped with a hydraulic breaker is limited to 1-2 times the length of the breaker. After excavating to the preset excavation advance, repair and level the excavation face, and promptly measure and verify it. Repair any under-excavated parts until the designed excavation outline is reached. Then, operate the machine to retreat and lift the support trolley to the working face for initial support. After the support is completed, one cycle of operation is finished. Then repeat the cycle of operation until the lower bench of the left tunnel and the lower bench of the right tunnel are connected and the lower bench construction is completed.

[0026] In step five above, based on the tunnel monitoring and measurement results, once the deformation values ​​of the left and right lower steps of the tunnel are within the design allowable range and remain stable, construction on the left and right sides proceeds simultaneously. After surveying and setting out, an excavator equipped with a hydraulic breaker is used to break and excavate in front, and the excavator is used in conjunction with dump trucks to remove the slag. Then, after excavating to the preset excavation depth, the excavation face is repaired and leveled, and timely measurement and verification are carried out. Any under-excavated parts are repaired until the designed excavation outline is reached. Then, the machine is operated to retreat, and the support trolley is lifted to the working face for initial support. After the support is completed, one cycle of operation is finished. This cycle of operation is then repeated until the left and right invert arches are connected. Once the invert arch construction is completed, the tunnel construction is finished.

[0027] Based on the above, the advantages of this invention are as follows: This invention applies a combined cantilever tunneling machine and hydraulic breaker combination to the construction of large-span arch tunnels in sensitive urban areas, innovating tunnel excavation techniques. Mechanical excavation causes minimal disturbance to the surrounding rock, which is beneficial to the stability of the surrounding rock and the safety of tunnel construction and surrounding vibration-sensitive structures. Furthermore, it adopts a simultaneous mechanical excavation and muck removal method, replacing the traditional step-by-step method of drilling, blasting, ventilation, and muck removal, simplifying the work process and improving efficiency. The innovative application of the combined cantilever tunneling machine and hydraulic breaker combination allows for horizontal excavation of the upper bench using the cantilever tunneling machine during segmented tunnel excavation, while the lower bench is excavated using the hydraulic breaker. The breaker utilizes the free face formed by the upper step for vertical excavation and crushing, creating a situation where two or more working faces can operate in parallel. This improves the mechanization of tunnel construction, increases construction efficiency, significantly reduces the number of construction workers, enhances construction safety, and avoids tunnel mass injury accidents. At the same time, the cutting head of the cantilever tunnel boring machine can adapt well to changes in the strength of the surrounding rock and the requirements of contour excavation, ensuring the smoothness of the tunnel's perimeter contour and avoiding over-excavation and under-excavation that often occur in blasting excavation. The excavated contour is smooth and rounded, avoiding the problem of local stress concentration, resulting in a good tunnel contour shaping effect. It also reduces the amount of over-excavation and under-excavation, saves on the amount of concrete spraying required for subsequent construction, and effectively reduces construction costs.

[0028] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A mechanical excavation method for large-span continuous arch hard rock tunnels, comprising the following steps: Step 1: Pre-construction planning; Step 2: Construction of the central pilot tunnel; Step 3: Construction of the upper bench; Step 4: Construction of the lower bench; Step 5: Construction of the invert arch; Its characteristics are: In step one above, the entire cross-section of the large-span arch tunnel is divided into seven parts: the central pilot tunnel, the upper bench of the left tunnel, the lower bench of the left tunnel, the invert of the left tunnel, the upper bench of the right tunnel, the lower bench of the right tunnel, and the invert of the right tunnel. The central pilot tunnel, the upper bench of the left tunnel, and the upper bench of the right tunnel are excavated using a cantilever tunneling machine, while the lower bench of the left tunnel, the invert of the left tunnel, the lower bench of the right tunnel, and the invert of the right tunnel are excavated using a hydraulic breaker. In step two above, according to the construction drawings, the construction position of the central tunnel is determined by measuring instruments. The cantilever tunneling machine is then moved to the tunnel face to cut and excavate in front. A transport machine is connected to the rear to lift and transport the excavated material, which is then placed into a truck. The truck then passes through the support trolley to discharge the material outside the tunnel. After the excavation reaches the preset excavation depth, the excavation face is repaired and leveled, and timely measurement and verification are carried out. Any under-excavated parts are repaired until the designed excavation outline is reached. Then, the machine is operated to retreat, and the support trolley is lifted to the tunnel face for initial support. After the support is completed, one cycle of operation is finished. This cycle of operation is then repeated until the central tunnel is completed. Then, the central partition wall is constructed, and the concrete of the central partition wall reaches the design strength. The construction of the central tunnel is then completed. In step three above, the upper steps of the left and right tunnels are divided into a sequential construction order, designated as the first and second main tunnels respectively, and constructed sequentially. The gap between the surrounding rock and the central partition wall of the second main tunnel is then backfilled with earth and rock. Next, construction begins on the first main tunnel, with the cantilever tunneling machine positioned at the tunnel face to cut and excavate. Muck is then transported by a transport machine or excavator and removed by trucks. After reaching the predetermined excavation depth, the excavation face is leveled and measured for verification. The under-excavated parts are trimmed until the designed excavation outline is reached. Then the machine is moved back and the support trolley is lifted to the working face for initial support. After the support is completed, one cycle of operation is completed. Then the cycle of operation is repeated until the main tunnel is completed. Before the main tunnel is completed, after the distance between the working face of the main tunnel and the working face of the secondary main tunnel reaches the design standard, the backfill soil and rock are cleared and transported out, and the construction of the secondary main tunnel is carried out in coordination. The construction process is the same as that of the main tunnel until the secondary main tunnel is completed and the upper step construction is completed. In step four above, construction is carried out simultaneously on the left and right sides. The excavation edge lines of the left tunnel invert and the right tunnel invert are measured and marked out respectively. Based on these limits, an excavator equipped with a hydraulic breaker is used to break and excavate in front, and the excavator is used in conjunction with a dump truck to remove the slag. After the excavation reaches the preset excavation depth, the excavation face is repaired and leveled, and timely measurement and verification are carried out. Any under-excavated parts are repaired until the designed excavation outline is reached. Then, the machine is operated to retreat, and the support trolley is lifted to the working face for initial support. After the support is completed, one cycle of operation is completed. Then, the cycle of operation is repeated until the lower bench of the left tunnel and the lower bench of the right tunnel are connected and the lower bench construction is completed. In step five above, based on the tunnel monitoring and measurement results, once the deformation values ​​of the left and right lower steps of the tunnel are within the design allowable range and remain stable, construction on the left and right sides proceeds simultaneously. After surveying and setting out, an excavator equipped with a hydraulic breaker is used to break and excavate in front, and the excavator is used in conjunction with dump trucks to remove the slag. Then, after excavating to the preset excavation depth, the excavation face is repaired and leveled, and timely measurement and verification are carried out. Any under-excavated parts are repaired until the designed excavation outline is reached. Then, the machine is operated to retreat, and the support trolley is lifted to the working face for initial support. After the support is completed, one cycle of operation is finished. This cycle of operation is then repeated until the left and right invert arches are connected. Once the invert arch construction is completed, the tunnel construction is finished.

2. The mechanical excavation method for a large-span continuous arch hard rock tunnel according to claim 1, characterized in that: In step two, the preset excavation advance of the cantilever tunneling machine is limited to 1 to 2 cutting head lengths.

3. The mechanical excavation method for a large-span continuous arch hard rock tunnel according to claim 1, characterized in that: In step two, the tunneling process of the cantilever tunneling machine is as follows: after the cantilever tunneling machine is in place, a groove is first cut horizontally from the bottom of the working face at high speed. The tunneling machine is then moved forward and placed in place again. After being in place, the cutting head adopts a bottom-up, left-right cyclic cutting method to excavate from the bottom to the arch. After completion, a second trimming is performed at low speed to accurately adjust the cross-section to meet the requirements of the cross-section size.

4. The mechanical excavation method for a large-span continuous arch hard rock tunnel according to claim 1, characterized in that: In step two, the cutting method of the cantilever tunneling machine is to start cutting from the bottom and then cut the upper part step by step according to the S-shaped or Z-shaped left and right circular upward cutting route. The right-hand rotating cutting head is used to cut hard rock. First, cut from the bottom from right to left, and then cut from left to right and from bottom to top step by step. If the rock with high joint development is encountered, the cutting method of the cantilever tunneling machine is to cut from the direction of rock joints step by step.

5. The mechanical excavation method for a large-span continuous arch hard rock tunnel according to claim 1, characterized in that: In step three, the staggered distance between the working faces of the first and subsequent main tunnels is 30 meters.

6. The mechanical excavation method for a large-span continuous arch hard rock tunnel according to claim 1, characterized in that: In step four, the preset excavation advance of the excavator equipped with a hydraulic breaker is limited to 1 to 2 times the length of the breaker.

7. The mechanical excavation construction method for a large-span continuous arch hard rock tunnel according to claim 1, characterized in that: In step five, the excavation process of the excavator equipped with a hydraulic breaker is as follows: the excavator operates at the bottom of the completed tunnel, keeping the hydraulic breaker vertical and excavating from top to bottom. When encountering hard rock, the angle between the excavator's boom and the hydraulic breaker is changed, and the rock is broken from top to bottom, left to right in sequence. Each direction is hit 2 to 3 times, each time for 2 to 4 seconds, to break the hard rock.

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