A reverse construction structure and construction method of a multi-arch tunnel under steep cliff conditions

Abstract

The present invention discloses a reverse construction structure and construction method for a multi-arch tunnel under steep cliff conditions, including a multi-arch tunnel entering the steep cliff, a separated tunnel provided on one side of the multi-arch tunnel, and a construction transverse tunnel arranged along the side of a deep "V" canyon; and the multi-arch tunnel, the separated tunnel, and the construction transverse tunnel intersect and connect with each other. By adding the construction transverse tunnel, the multi-arch tunnel and the separated tunnel can be constructed synchronously and reversely according to a pre-set construction process. The present invention has a simple structure and high construction convenience, which can ensure efficient and safe construction while reducing construction cost investment; and by adding the construction transverse tunnel, reverse construction can be carried out from the inside, without the need for large-scale excavation and brushing outside the tunnel, thus avoiding environmental damage, and having high construction safety. It can also achieve simultaneous construction of multiple faces, which can greatly improve the construction progress of the project and increase efficiency.

Description

Technical Field

[0001] The invention relates to a reverse construction structure of a multi-arch tunnel under steep cliff conditions and a construction method thereof, belonging to the technical field of tunnel construction. Background Art

[0002] With the continuous expansion of expressways in western mountainous areas, crossing deep V-shaped canyons is a common occurrence. Crossing deep V-shaped canyons typically employs a "tunnel + super-large bridge + tunnel" construction approach. Deep V-shaped canyons are characterized by steep cliffs and dangerous rock masses, as well as rockfall. These steep cliffs complicate the design of slope protection, tunnels, bridges, and other specialized projects, resulting in complex transitions between construction processes. The establishment of construction sites and access roads is particularly challenging under these conditions. Layout of these access roads is crucial to increase the working surface area on both sides of the canyon, thereby accelerating tunnel construction progress and shortening the construction period. Tunnels along deep V-shaped canyons are typically constructed as continuous arch tunnels, with narrow clearances, or even bifurcated tunnels, depending on the bridge structure and alignment. To achieve rapid construction of continuous arch tunnels under steep cliffs, a conventional approach is to build access roads and erect construction platforms at the tunnel entrances, excavating inward from the continuous arch tunnel entrance. However, constructing access roads under steep cliffs is challenging, as extensive excavation and brushing can easily cause environmental damage and pose significant challenges, including the high cost of slope protection. The construction of the portal construction platform often interferes with the construction of structures such as portal slope protection and bridge pile foundations, posing high safety risks and complex construction procedures. If one process is affected, the entire project process will be affected. The length of the tunnels on either side of the deep "V" canyon is crucial to the progress and schedule of the entire project. When the tunnels on either side of the deep "V" canyon are short, single-head excavation can be used. However, when the tunnels on either side of the deep "V" canyon are long or extra-long, single-head excavation cannot meet the construction schedule requirements. In this case, to excavate a multi-arch tunnel connected to a super-large bridge under steep cliff conditions, the only option is to lay a construction tunnel on the side of the mountain, enter the main tunnel through the construction tunnel, and then construct the multi-arch tunnel in the reverse direction. To address the issue of multi-arch tunnel construction under steep cliff conditions, in-depth and detailed research on a multi-arch tunnel construction method using the construction tunnel under steep cliff conditions is of great practical significance. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a reverse construction structure and construction method of a multi-arch tunnel under steep cliff conditions, which can overcome the shortcomings of the existing technology.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] A reverse construction structure for a multi-arch tunnel under steep cliff conditions includes a multi-arch tunnel entering the steep cliff, a separated tunnel provided on one side of the multi-arch tunnel, and a construction cross tunnel arranged along the side of a deep "V" canyon; and the multi-arch tunnel, the separated tunnel and the construction cross tunnel intersect and connect with each other.

[0006] The aforementioned multi-arch tunnel includes the right span of the multi-arch tunnel and the left span of the multi-arch tunnel, with a central guide tunnel provided between the two; the separated tunnel includes the right span of the separated tunnel and the left span of the separated tunnel, which gradually approach each other along the direction of the multi-arch tunnel and whose small clear distance sections are connected with the multi-arch tunnel; the construction cross tunnel is arranged transversely relative to the multi-arch tunnel and the separated tunnel and passes through the left and right spans of the two tunnels.

[0007] The aforementioned construction cross tunnel intersects with the end of the middle guide tunnel of the multi-arch tunnel or a position close to the end of the middle guide tunnel.

[0008] The aforementioned construction cross tunnel intersects with the front section of the middle pilot tunnel of the multi-arch tunnel and is 100-120 meters away from the end of the middle pilot tunnel of the multi-arch tunnel; or the construction cross tunnel intersects with the small clearance section at the end of the separated tunnel and is 150-160 meters away from the end of the middle pilot tunnel of the multi-arch tunnel.

[0009] A reverse construction method for a multi-arch tunnel under steep cliff conditions is disclosed. According to the terrain, a construction cross tunnel is arranged on the side of a deep "V" canyon until it intersects with the multi-arch tunnel and the separated tunnel. Through the construction cross tunnel, the multi-arch tunnel and the separated tunnel are constructed synchronously and reversely according to a pre-set construction process.

[0010] The aforementioned reverse construction method comprises the following specific steps:

[0011] s1. Excavate a construction tunnel along the side of the deep "V" canyon. The construction tunnel is arranged transversely to the multi-arch tunnel and the separated tunnel and intersects and connects with the left and right wings of the tunnel;

[0012] s2. Carry out the construction of the pilot tunnel in the multi-arch tunnel by constructing the cross tunnel until the tunnel is constructed;

[0013] s3. After the intermediate pilot tunnel is constructed for a certain distance, the excavation of the separated tunnel is carried out in the reverse direction simultaneously: the construction of the right and left wings of the separated tunnel is carried out synchronously according to the distance;

[0014] s4. After the middle pilot tunnel described in step s2 is excavated, the excavation construction of the multi-arch tunnel is carried out: the construction of the middle wall of the multi-arch tunnel, the right span of the multi-arch tunnel and the left span of the multi-arch tunnel is carried out synchronously according to the distance.

[0015] In the aforementioned reverse construction method, in steps s1 and s2, a transverse tunnel is excavated along the side of the deep "V" canyon, and the transverse tunnel intersects with the end of the middle guide tunnel of the multi-arch tunnel or a position near the end of the middle guide tunnel; the left and right connecting passages are expanded at the intersection to connect the right and left main tunnels of the tunnel; wherein, the left and right connecting passages are backfilled and sealed with C30 concrete after the left tunnel main tunnel is excavated to the vehicle-carrying construction transverse tunnel.

[0016] In the aforementioned reverse construction method, when the construction cross tunnel intersects with the end of the middle pilot tunnel of the multi-arch tunnel, the middle pilot tunnel is excavated along the end of the middle pilot tunnel of the multi-arch tunnel until the middle pilot tunnel exits the tunnel;

[0017] When the construction cross tunnel intersects with the front section of the middle pilot tunnel of the multi-arch tunnel, the middle pilot tunnel is excavated simultaneously and in the opposite direction along the intersection until the middle pilot tunnel exits the tunnel;

[0018] When the construction cross tunnel intersects with the small clearance section at the end of the separated tunnel, the small clearance section is first constructed to the end of the middle guide tunnel, and then the middle guide tunnel is excavated along the end of the middle guide tunnel of the multi-arch tunnel until the middle guide tunnel exits the tunnel.

[0019] In the aforementioned reverse construction method, in step s3, during the construction of the middle pilot tunnel, the right and left spans of the separated tunnel are constructed simultaneously, and the distance between the middle pilot tunnel face and the right span face of the separated tunnel is at least 3B, and the distance between the right span face of the separated tunnel and the left span face of the separated tunnel is at least 3B, where B is the diameter of the end of the multi-arch tunnel.

[0020] In the aforementioned reverse construction method, in step s4, after the middle guide tunnel is excavated, the middle wall, right span and left span of the multi-arch tunnel are synchronously constructed along the intersection of the construction cross tunnels, and the distance between the middle wall and the right span heading face of the multi-arch tunnel is at least 3B and the maintenance cycle meets the requirements, and the distance between the right span heading face of the multi-arch tunnel and the left span heading face of the multi-arch tunnel is at least 3B, where B is the diameter of the end of the multi-arch tunnel.

[0021] Compared with the prior art, the present invention discloses a reverse construction structure and construction method of a continuous arch tunnel under steep cliff conditions, which includes a continuous arch tunnel entering the steep cliff, a separated tunnel provided on one side of the continuous arch tunnel, and a construction transverse tunnel arranged along the side of a deep "V" canyon; and the continuous arch tunnel, the separated tunnel and the construction transverse tunnel are mutually intersected and connected. By adding the construction transverse tunnel, the continuous arch tunnel and the separated tunnel can be constructed synchronously and in reverse according to a pre-set construction process. First, the construction transverse tunnel is arranged on the side of the deep "V" canyon according to the terrain, which can effectively utilize the canyon terrain structure for construction, with less disturbance to the surrounding environment, while ensuring efficient and safe construction, reducing the investment in construction costs; secondly, by adding the construction transverse tunnel, reverse construction can be carried out from the inside, without the need for large-scale excavation and brushing outside the tunnel, thus avoiding environmental damage, with high construction safety, and multiple faces can be constructed simultaneously, which can greatly improve the construction progress of the project and increase efficiency.

[0022] The beneficial effects of the present invention are:

[0023] (1) Influenced by the bridge structure and the route direction, the two sides of the deep "V" canyon are mostly set up as continuous arch tunnels. In order to quickly construct the continuous arch tunnels and reduce the excavation damage to the steep cliffs caused by the construction of temporary roads and the construction platform, the present invention has a simple structure and high construction convenience. By laying a construction tunnel on the side of the deep "V" canyon, the main tunnel is excavated from the construction tunnel, which can reduce the damage to the steep cliff rock mass caused by tunnel excavation and reduce the impact on the bridge structure below and the side slope protection construction;

[0024] (2) The present invention can realize the simultaneous construction of multiple faces, and the overall coordination between the various construction processes, saving construction time while ensuring safety, and has strong practicality and high promotion potential.

[0025] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings, in which:

[0027] Figure 1 This is a schematic structural diagram of Example 1 of the present invention;

[0028] Figure 2 This is a construction process diagram corresponding to Example 1 of the present invention;

[0029] Figure 3 The construction process corresponding to Example 1 of the present invention Figure 1 ;

[0030] Figure 4 The construction process corresponding to Example 1 of the present invention Figure 2 ;

[0031] Figure 5 The construction process corresponding to Example 1 of the present invention Figure 3 ;

[0032] Figure 6 The construction process corresponding to Example 1 of the present invention Figure 4 ;

[0033] Figure 7 The construction process corresponding to Example 1 of the present invention Figure 5 ;

[0034] Figure 8 This is a schematic structural diagram of Example 2 of the present invention;

[0035] Figure 9 This is a construction process diagram corresponding to Example 2 of the present invention;

[0036] Figure 10 The construction process corresponding to Example 2 of the present invention Figure 1 ;

[0037] Figure 11 The construction process corresponding to Example 2 of the present invention Figure 2 ;

[0038] Figure 12 The construction process corresponding to Example 2 of the present invention Figure 3 ;

[0039] Figure 13 The construction process corresponding to Example 2 of the present invention Figure 4 ;

[0040] Figure 14 The construction process corresponding to Example 2 of the present invention Figure 5 ;

[0041] Figure 15 This is a schematic structural diagram of Example 3 of the present invention;

[0042] Figure 16 This is the construction process corresponding to Example 3 of the present invention Figure 1 ;

[0043] Figure 17 This is the construction process corresponding to Example 3 of the present invention Figure 2 ;

[0044] Figure 18 This is the construction process corresponding to Example 3 of the present invention Figure 3 ;

[0045] Figure 19 This is the construction process corresponding to Example 3 of the present invention Figure 4 ;

[0046] Figure 20 This is the construction process corresponding to Example 3 of the present invention Figure 5 ;

[0047] Figure 21 This is the construction process corresponding to Example 3 of the present invention Figure 6 . DETAILED DESCRIPTION

[0048] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the preferred embodiments are only for illustrating the present invention, and are not intended to limit the scope of protection of the present invention.

[0049] like Figures 1-21As shown, a reverse construction structure of a multi-arch tunnel under steep cliff conditions includes a multi-arch tunnel entering the steep cliff, a separated tunnel is provided on one side of the multi-arch tunnel, and a construction cross tunnel 1 is arranged along the side of the deep "V" canyon; and the multi-arch tunnel, the separated tunnel and the construction cross tunnel 1 are mutually intertwined and connected.

[0050] The multi-arch tunnel includes a right span 6 and a left span 7 of the multi-arch tunnel, with a central guide tunnel 2 provided between the two; the separated tunnel includes a right span 3 and a left span 4 of the separated tunnel, which gradually approach each other along the direction of the multi-arch tunnel and whose small clear distance sections are connected with the multi-arch tunnel; the construction cross tunnel 1 is arranged transversely relative to the multi-arch tunnel and the separated tunnel and passes through the left and right spans of the two tunnels.

[0051] The construction cross tunnel 1 intersects with the end of the middle guide tunnel 2 of the multi-arch tunnel or a position close to the end of the middle guide tunnel 2. The middle guide tunnel 2 is constructed first through the construction cross tunnel 1, and then the multi-arch tunnel and the separated tunnel are constructed simultaneously and in reverse to exit the tunnel, thereby reducing the damage of tunnel excavation to the steep cliff rock mass and reducing the impact on the bridge structure below and the side slope protection construction.

[0052] Preferably, the construction cross tunnel 1 intersects with the front section of the pilot tunnel 2 in the multi-arch tunnel and is 100-120 meters away from the end of the pilot tunnel 2 in the multi-arch tunnel, or the construction cross tunnel 1 intersects with the small clearance section at the end of the separated tunnel and is 150-160 meters away from the end of the pilot tunnel 2 in the multi-arch tunnel.

[0053] The width of the construction tunnel 1 is at least 4.5 m.

[0054] A reverse construction method for a multi-arch tunnel under steep cliff conditions is disclosed. According to the terrain, a construction cross tunnel 1 is arranged on the side of a deep "V" canyon until it intersects with the multi-arch tunnel and the separated tunnel. Through the construction cross tunnel 1, the multi-arch tunnel and the separated tunnel are constructed synchronously and reversely according to a pre-set construction procedure.

[0055] The specific steps include:

[0056] s1. Dig a construction tunnel 1 along the side of the deep "V" canyon. The construction tunnel 1 is arranged transversely to the multi-arch tunnel and the separated tunnel and intersects and connects with the left and right wings of the tunnel;

[0057] s2. Carry out construction of the pilot tunnel 2 in the multi-arch tunnel by constructing the transverse tunnel 1 until the tunnel is completed;

[0058] s3. After the intermediate pilot tunnel 2 is constructed for a certain distance, the excavation of the separated tunnel is carried out in the reverse direction simultaneously: the construction of the right span 3 of the separated tunnel and the left span 4 of the separated tunnel is carried out synchronously according to the distance;

[0059] s4. After the middle guide tunnel 2 described in step s2 is excavated, the excavation construction of the multi-arch tunnel is carried out: the construction of the multi-arch tunnel middle wall, the multi-arch tunnel right span 6 and the multi-arch tunnel left span 7 is carried out synchronously according to the distance.

[0060] In step s1, a cross tunnel 1 is excavated along the side of the deep "V" canyon toward the end of the pilot tunnel 2 in the multi-arch tunnel until it intersects with the multi-arch tunnel and the separated tunnel. The left and right connecting passages 5 are expanded at the intersection to connect the right and left main tunnels of the tunnel.

[0061] Specifically, a transverse tunnel 1 is excavated along the side of a deep "V" canyon, and the transverse tunnel 1 intersects with the end of the middle pilot tunnel 2 of the multi-arch tunnel or a position close to the end of the middle pilot tunnel 2; wherein, the transverse tunnel 2 may intersect with the front section of the middle pilot tunnel 2 of the multi-arch tunnel and be 100-120 meters away from the end of the middle pilot tunnel 2 of the multi-arch tunnel, or the transverse tunnel 1 may intersect with the small clearance section at the end of the separated tunnel and be 150-160 meters away from the end of the middle pilot tunnel 2 of the multi-arch tunnel;

[0062] Among them, the width of the construction cross tunnel 1 and the left and right connecting channels 5 is at least 4.5m.

[0063] In step s2, when the construction cross tunnel 1 intersects with the end of the middle pilot tunnel 2 of the multi-arch tunnel, the middle pilot tunnel 2 is excavated along the end of the middle pilot tunnel 2 of the multi-arch tunnel until the middle pilot tunnel exits the tunnel;

[0064] When the construction cross tunnel 1 intersects with the front section of the middle pilot tunnel 2 of the multi-arch tunnel, the middle pilot tunnel 2 is excavated simultaneously and in the opposite direction along the intersection until the middle pilot tunnel exits the tunnel;

[0065] When the construction cross tunnel 1 intersects with the small clearance section at the end of the separated tunnel, the small clearance section is first constructed to the end of the middle guide tunnel 2, and then the middle guide tunnel 2 is excavated along the end of the middle guide tunnel 2 of the multi-arch tunnel until the middle guide tunnel exits the tunnel;

[0066] After the middle guide tunnel 2 is constructed, the middle wall construction materials of the multi-arch tunnel, including steel bars, formwork, pumping pipes and other materials, are transported through the middle guide tunnel 2. The materials are placed in sequence from the entrance of the middle guide tunnel 2 to the intersection of the construction cross tunnel 1.

[0067] In step s3, during the construction of the middle guide tunnel 2, the construction of the right and left main tunnels of the separated tunnel is carried out simultaneously, and the distance between the heading face of the middle guide tunnel 2 and the heading face of the right span 3 of the separated tunnel is at least 3B, and the distance between the heading face of the right span 3 of the separated tunnel and the heading face of the left span 4 of the separated tunnel is at least 3B, where B is the diameter of the end of the multi-arch tunnel.

[0068] Specifically, the construction of the middle guide tunnel 2 is carried out first. When the heading face of the middle guide tunnel 2 is at least 3B away from the end of the main tunnel of the right span 3 of the separated tunnel, the excavation construction of the right span 3 of the separated tunnel is started along the exit of the multi-arch tunnel; when its construction heading face is at least 3B away from the intersection, the construction of the left span 4 of the separated tunnel is carried out at the same time, and the subsequent construction process always keeps the distance between the heading faces of the right span 3 of the separated tunnel and the left span 4 of the separated tunnel at least 3B.

[0069] In step s4, after the middle guide tunnel 2 is excavated, the middle wall of the multi-arch tunnel, the right span 6 of the multi-arch tunnel, and the left span 7 of the multi-arch tunnel are synchronously constructed along the intersection of the construction cross tunnel 1. The distance between the middle wall and the heading face of the right span 6 of the multi-arch tunnel is at least 3B and the maintenance cycle meets the requirements. The distance between the heading face of the right span 6 of the multi-arch tunnel and the heading face of the left span 7 of the multi-arch tunnel is at least 3B, where B is the diameter of the end of the multi-arch tunnel.

[0070] Specifically, when the construction distance of the middle wall of the multi-arch tunnel is at least 3B from the intersection and the maintenance period meets the requirements, the construction of the right span 6 of the multi-arch tunnel begins; when the heading face of the right span 6 of the multi-arch tunnel is at least 3B away from the heading face of the left span 7 of the multi-arch tunnel, the left span 7 of the multi-arch tunnel is excavated at the same time, and the subsequent construction process always maintains a distance of at least 3B between the middle wall of the multi-arch tunnel and the heading faces of the right span 6 and the left span 7 of the multi-arch tunnel.

[0071] During the construction of the middle wall, a connecting channel 5 between the left and right sections is reserved as a transportation channel for the left tunnel. After the main tunnel of the left tunnel is excavated to the cross tunnel for vehicle construction, C30 concrete is used to block this transportation channel.

[0072] Example 1,

[0073] The following is combined with Figure 1-Figure 7 The present invention is further described.

[0074] The specific construction steps when the construction cross tunnel 1 intersects with the end of the pilot tunnel 2 in the multi-arch tunnel are as follows:

[0075] 1) A construction tunnel is laid on the side of the deep "V" canyon. The excavated construction tunnel intersects with the end of the pilot tunnel 2 of the multi-arch tunnel. The left and right connecting passages 5 are further excavated at the intersection to connect the right and left main tunnels of the tunnel.

[0076] 2) Construction of the middle pilot tunnel 2 of the multi-arch tunnel will begin. When the distance between the middle pilot tunnel 2 face and the intersection reaches 3B, the excavation of the right span 3 small clean section of the separated tunnel will be started along the exit of the multi-arch tunnel.

[0077] 3) When the distance between the right span 3 of the separated tunnel and the intersection reaches 3B, the construction of the left span 4 of the separated tunnel will start at the same time;

[0078] 4) After the excavation of the middle pilot tunnel 2 is completed, the construction materials for the middle wall of the multi-arch tunnel, including steel bars, formwork, pumping pipes, etc., are transported through the middle pilot tunnel 2. The materials are placed in sequence from the entrance of the middle pilot tunnel to the intersection of the construction cross tunnel 1 inside the tunnel. After the materials are placed, the construction of the middle wall of the multi-arch tunnel begins. The middle wall is constructed along the entrance of the multi-arch tunnel.

[0079] During the construction of the middle wall, the left and right connecting passages 5 are set at the starting point of the middle wall and kept unobstructed. They serve as the transportation passage of the left tunnel. After the main tunnel of the left tunnel is excavated to the vehicle cross passage, C30 concrete is used to block this transportation passage.

[0080] 5) When the middle wall of the multi-arch tunnel is 3B away from the intersection and the curing period meets the requirements, the right span 6 of the multi-arch tunnel will be constructed;

[0081] 6) When the distance between the right span 6 of the multi-arch tunnel and the left span 7 of the multi-arch tunnel exceeds 3B, the left span 7 of the multi-arch tunnel shall be excavated simultaneously;

[0082] Among them, B is the diameter of the end of the multi-arch tunnel. The construction method can realize the simultaneous excavation of multiple faces. The two faces are excavated along the intersection, the entrance end of the multi-arch tunnel is constructed for the multi-arch tunnel, and the reverse direction is the separated tunnel construction, which greatly improves the construction progress.

[0083] Example 2,

[0084] The following is combined with Figures 8-14 The present invention is further described.

[0085] The specific construction steps when the construction cross tunnel 1 intersects with the front section of the pilot tunnel 2 in the multi-arch tunnel are as follows:

[0086] 1) Construction tunnel 1 is laid out on the side of the deep "V" canyon. Excavation of construction tunnel 1 intersects with the front section of the middle pilot tunnel 2 of the multi-arch tunnel. The intersection is 100 meters away from the end of the middle pilot tunnel.

[0087] 2) Start construction of the front section of the central pilot tunnel along the entrance direction of the multi-arch tunnel by constructing the transverse tunnel 1. When the construction length is at least 3B, start construction of the rear section of the central pilot tunnel in the reverse direction.

[0088] 3) After the excavation of the central pilot tunnel in the front section is completed, the construction materials for the middle wall of the multi-arch tunnel, including steel bars, formwork, pumping pipes, etc., are transported in. The materials are placed in sequence from the entrance of the central pilot tunnel to the intersection of the cross tunnels inside the tunnel. After the materials are placed, the construction of the middle wall of the multi-arch tunnel begins. The middle wall is constructed along the direction of the multi-arch tunnel entrance.

[0089] At the same time, after the excavation of the rear middle pilot tunnel is completed, the middle wall will be cast along the entrance direction of the multi-arch tunnel;

[0090] During the construction of the middle wall, a 4.5-meter-wide horizontal tunnel was reserved at the intersection as the connecting passage 5 between the left and right sections. After the main tunnel of the left section was excavated to the vehicle cross passage, the middle wall and the main tunnel lining were built.

[0091] 4) When the distance between the middle wall of the multi-arch tunnel and the intersection is at least 3B and the curing period meets the requirements, the construction of the right span 6 of the multi-arch tunnel shall be started; when the tunnel face of the right span 6 of the multi-arch tunnel is more than 3B away from the tunnel face of the left span 7 of the multi-arch tunnel, the left span 7 of the multi-arch tunnel shall be excavated at the same time;

[0092] 5) When the distance between the left span 7 of the multi-arch tunnel and the intersection is at least 3B, the construction of the right span 3 of the separated tunnel will begin; when the distance between the right span 3 of the separated tunnel and the intersection reaches 3B, the construction of the left span 4 of the separated tunnel will begin simultaneously;

[0093] Among them, B is the diameter of the end of the multi-arch tunnel. The construction method can realize the simultaneous construction of multiple working surfaces. The intersection is constructed along the entrance of the multi-arch tunnel for the multi-arch tunnel, and the reverse direction is constructed for the multi-arch tunnel and the separated tunnel, which has high construction efficiency.

[0094] Example 3,

[0095] The following is combined with Figures 15-21 The present invention is further described.

[0096] The specific construction steps when the construction cross tunnel 1 intersects with the small clearance section at the end of the separated tunnel are:

[0097] 1) Lay out the construction tunnel 1 on the side of the deep "V" canyon, and excavate the small clearance section from the tunnel 1 to the end of the separated tunnel. The intersection position is located 150 meters away from the end of the pilot tunnel 2 in the multi-arch tunnel;

[0098] 2) Construct the small clearance section of the right main tunnel along the exit direction of the multi-arch tunnel. When the construction length is at least 3B, start excavating the small clearance section of the right reverse direction along the direction of the multi-arch tunnel.

[0099] 3) When the construction distance between the two directions of the small clearance section is at least 6B, the left and right connecting channels 5 are constructed along the middle position of the excavated section, and the width of the left and right connecting channels 5 is at least 4.5 meters;

[0100] 4) After the construction of the left and right connecting passages is completed, the left section with a small clearance distance will be excavated in the reverse direction of the arch tunnel entrance. When the 3B length is constructed, the left section with a small clearance distance of the main tunnel will be constructed in the direction of the arch tunnel exit.

[0101] 5) When the right span narrow clearance section is constructed to the end of the middle pilot tunnel 2, the construction of the right span main tunnel is stopped. A transverse passage 8 is excavated along the inner side of the right span main tunnel to the middle pilot tunnel of the multi-arch tunnel. The entrance of the transverse passage 8 should be at least 5 meters wide to facilitate the transition from the main tunnel to the middle pilot tunnel 2. After the construction of the middle pilot tunnel 2 is completed, the transverse passage 8 can be sealed with C30 concrete.

[0102] 6) After the excavation of the middle pilot tunnel 2 is completed, the construction materials for the middle wall of the multi-arch tunnel, including steel bars, formwork, pumping pipes, etc., are transported through the middle pilot tunnel 2. The materials are placed in sequence from the entrance of the middle pilot tunnel 2 to the intersection of the construction cross tunnel 1. After the materials are placed, the cross passage 8 is backfilled with C30 concrete, and the construction of the middle wall of the multi-arch tunnel begins. The middle wall is constructed along the direction of the multi-arch tunnel entrance.

[0103] After the middle wall construction is completed, C30 concrete is used to backfill the left and right connecting channels 5;

[0104] 7) When the distance between the middle wall of the multi-arch tunnel and the end of the multi-arch tunnel is at least 3B and the curing period meets the requirements, the construction of the right span 6 of the multi-arch tunnel shall be started; when the tunnel face of the right span 6 of the multi-arch tunnel is more than 3B away from the tunnel face of the left span 7 of the multi-arch tunnel, the left span 7 of the multi-arch tunnel shall be excavated at the same time;

[0105] Among them, B is the diameter of the end of the multi-arch tunnel. The construction method can realize the simultaneous construction of multiple working surfaces, and the construction efficiency is high.

[0106] The above description is only a preferred embodiment of the present invention and does not constitute any form of confidentiality restriction on the present invention. Any simple modification, equivalent change and modification of the above embodiment that does not deviate from the content of the technical solution of the present invention and is based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A reverse construction method for a multi-arch tunnel under steep cliff conditions, characterized by: According to the terrain, a construction tunnel (1) is arranged on the side of the deep "V" canyon until it intersects with the continuous arch tunnel and the separated tunnel, and the continuous arch tunnel and the separated tunnel are constructed synchronously and reversely according to the pre-set construction process through the construction tunnel (1); The specific steps include: s1. Excavating a construction transverse tunnel (1) along the side of a deep "V" canyon, wherein the construction transverse tunnel (1) is arranged transversely relative to the continuous arch tunnel and the separated tunnel and intersects and communicates with the left and right sides of the tunnel; s2. Construction of the pilot tunnel (2) of the multi-arch tunnel is carried out by constructing the transverse tunnel (1) until the tunnel is constructed; s3. After the intermediate pilot tunnel (2) is constructed for a certain distance, the excavation construction of the separated tunnel is carried out in the reverse direction simultaneously: the construction of the right section (3) of the separated tunnel and the left section (4) of the separated tunnel are carried out synchronously according to the distance; s4. After the middle guide tunnel (2) described in step s2 is excavated, the excavation construction of the multi-arch tunnel is carried out: the construction of the multi-arch tunnel middle wall, the multi-arch tunnel right section (6) and the multi-arch tunnel left section (7) is carried out synchronously according to the distance; In steps s1 and s2, a construction transverse tunnel (1) is excavated along the side of the deep "V" canyon, and the construction transverse tunnel (1) intersects with the end of the middle guide tunnel (2) of the multi-arch tunnel or a position close to the end of the middle guide tunnel (2); the left and right connecting passages (5) are expanded at the intersection to connect the right and left main tunnels of the multi-arch tunnel; wherein, the left and right connecting passages (5) are backfilled and sealed with C30 concrete after the left tunnel main tunnel is excavated to the vehicle construction transverse tunnel.

2. The reverse construction method for a multi-arch tunnel under steep cliff conditions according to claim 1 is characterized by: When the construction cross tunnel (1) intersects with the end of the middle guide tunnel (2) of the multi-arch tunnel, the middle guide tunnel (2) is excavated along the end of the middle guide tunnel (2) of the multi-arch tunnel until the middle guide tunnel exits the tunnel; When the construction cross tunnel (1) intersects with the front section of the middle guide tunnel (2) of the multi-arch tunnel, the middle guide tunnel (2) is excavated simultaneously and in the opposite direction along the intersection until the middle guide tunnel exits the tunnel; When the construction cross tunnel (1) intersects with the small clearance section at the end of the separated tunnel, the small clearance section is first constructed to the end of the middle guide tunnel (2), and then the middle guide tunnel (2) is excavated along the end of the middle guide tunnel (2) of the multi-arch tunnel until the middle guide tunnel exits the tunnel.

3. The reverse construction method for a multi-arch tunnel under steep cliff conditions according to claim 1 is characterized by: In step s3, during the construction of the middle guide tunnel (2), the construction of the right span (3) and the left span (4) of the separated tunnel is carried out simultaneously, and the distance between the working face of the middle guide tunnel (2) and the working face of the right span (3) of the separated tunnel is at least 3B, and the distance between the working face of the right span (3) of the separated tunnel and the working face of the left span (4) of the separated tunnel is at least 3B, where B is the diameter of the end of the multi-arch tunnel.

4. The reverse construction method for a multi-arch tunnel under steep cliff conditions according to claim 1 is characterized by: In step s4, after the middle guide tunnel (2) is excavated, the middle wall of the multi-arch tunnel, the right span (6) of the multi-arch tunnel and the left span (7) of the multi-arch tunnel are synchronously constructed along the intersection of the construction cross tunnel (1), and the distance between the middle wall and the face of the right span (6) of the multi-arch tunnel is at least 3B and the maintenance period meets the requirements, and the distance between the face of the right span (6) of the multi-arch tunnel and the face of the left span (7) of the multi-arch tunnel is at least 3B, where B is the diameter of the end of the multi-arch tunnel.

5. The reverse construction method for a multi-arch tunnel under steep cliff conditions according to any one of claims 1 to 4, characterized in that: It is used for the reverse construction structure construction of a multi-arch tunnel under steep cliff conditions. The reverse construction structure includes a multi-arch tunnel entering the steep cliff, a separated tunnel provided on one side of the multi-arch tunnel, and a construction transverse tunnel (1) arranged along the side of a deep "V" canyon; and the multi-arch tunnel, the separated tunnel and the construction transverse tunnel (1) are mutually intersected and connected.

6. The reverse construction method for a multi-arch tunnel under steep cliff conditions according to claim 5 is characterized by: The multi-arch tunnel comprises a right span (6) and a left span (7) of the multi-arch tunnel, with a middle guide tunnel (2) provided between the two. The separated tunnel comprises a right span (3) and a left span (4) of the separated tunnel, which gradually approach each other along the direction of the multi-arch tunnel and whose small clearance section is connected with the multi-arch tunnel. The construction transverse tunnel (1) is arranged transversely relative to the multi-arch tunnel and the separated tunnel and passes through the left and right spans of the multi-arch tunnel and the separated tunnel.

7. The reverse construction method for a multi-arch tunnel under steep cliff conditions according to claim 6 is characterized by: The construction transverse tunnel (1) intersects with the end of the middle guide tunnel (2) of the multi-arch tunnel or a position close to the end of the middle guide tunnel (2).

8. The reverse construction method for a multi-arch tunnel under steep cliff conditions according to claim 7 is characterized by: The construction cross tunnel (1) intersects with the front section of the pilot tunnel (2) of the multi-arch tunnel and is 100-120 meters away from the end of the pilot tunnel (2) of the multi-arch tunnel; or the construction cross tunnel (1) intersects with the small clearance section at the end of the separated tunnel and is 150-160 meters away from the end of the pilot tunnel (2) of the multi-arch tunnel.

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