A construction method and structure for a self-drilling and pile method tunnel to enter a multi-arch tunnel in advance

Abstract

A construction method for a self-drilling and pile method tunnel to enter a multi-arch tunnel in advance. After the side pilot tunnel of the drilling and pile method tunnel reaches the end, it continues to extend forward, and the extension length meets the construction space requirements of the transverse passage. Then, openings are made on the side walls of the side pilot tunnels on both sides in opposite directions, and the temporary transverse passage connects the openings of the side pilot tunnels on both sides. After the surrounding soil is reinforced and the temporary structure is strengthened, the portal of the main line of the multi-arch tunnel is demolished, and the upper half-section excavation of the multi-arch tunnel is carried out. The excavation of the lower half-section is carried out after the second lining and arch closure of the end wall of the drilling and pile method tunnel are completed. By using the side pilot tunnel of the drilling and pile method tunnel, a construction passage for the multi-arch tunnel is opened in advance, changing the series of processes into a parallel relationship, effectively improving the construction efficiency, better alleviating the contradiction between the difficulty of project land occupation and the construction period pressure, and also conforming to the concepts of green and energy conservation, with remarkable social and economic benefits and great significance.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel engineering, and particularly to a construction method and structure for a self-drilled and -piled tunnel to enter a multi-arch tunnel in advance, which is applicable to the under-excavation engineering and design method with complex site conditions and high settlement requirements. Background Art

[0002] In the existing drilled and piled tunnel method, the initial stress-bearing system is composed of side piles, middle piles (columns), top and bottom beams, and top arches to bear the loads during the construction process; its main idea is to organically combine the top-down method and the step-by-step under-excavation method, give full play to their respective advantages, and under the protection of the top cover, the soil body can be excavated layer by layer downward, and the secondary lining can be constructed. The construction can be carried out by two methods: the forward construction method and the reverse construction method. Finally, a permanent load-bearing system composed of the initial support and the secondary lining is formed. The structural form is generally shown in Figure 1 as shown. The drilled and piled method is a construction method applied to complex environmental conditions. Since a stable support system is formed first and then a large range of soil excavation is carried out, this method can effectively reduce the settlement and deformation of the stratum, thus achieving the purpose of protecting the surrounding environment. However, this method has many process conversions, low work efficiency, and affects the project duration. In the specific engineering design, the under-excavated tunnels mostly adopt a combined plan of different construction methods in combination with the actual conditions. In addition, in the downtown area of the city, the site provided for the project implementation is very limited, and the under-excavated tunnels of different construction methods can only be constructed from one heading face. In this case, it is mostly selected to start the construction from the drilled and piled tunnel, and then excavate the tunnels of other construction methods after the completion of the drilled and piled tunnel construction. This conventional practice results in low work efficiency and difficult to guarantee the project duration.

[0003] The multi-arch tunnel is a structural type restricted by site conditions, line conditions, and geological conditions and meeting functional requirements. Its advantage is to avoid large-section excavation of the structure and make effective use of space. The tunnel with separated initial support and secondary lining of the multi-arch tunnel is excavated by the CD method or the CRD method, and the structural form and construction steps are generally shown in Figures 2(1)-(8).

[0004] The conventional design method for the drilled and piled tunnel to enter the multi-arch tunnel in the existing technology is as follows: First step, complete the side pilot tunnels, side piles, middle pile columns, initial support, and secondary lining arch closure of the drilled and piled tunnel; Second step, pre-reinforce the periphery of the broken door of the end wall of the drilled and piled tunnel in advance and break the end piles; Third step, excavate the soil body of the multi-arch tunnel and complete the initial support construction. The schematic diagram of the interface between the drilled and piled tunnel and the multi-arch tunnel is shown in Figure 3 ; this practice makes the processes of the multi-arch tunnel and the drilled and piled tunnel form a series relationship, which is not conducive to improving the processes and difficult to meet the project duration requirements; therefore, it is urgently needed to be solved. Summary of the Invention

[0005] The present invention provides a construction method and structure for a self-pile-in-hole method tunnel to enter a multi-arch tunnel in advance, aiming to solve the technical problems of improving work efficiency and reducing the construction period pressure. The inventor of the present invention proposed a construction method for a pile-in-hole tunnel to enter a multi-arch tunnel in advance. Through the setting of a transition section, the construction working face and the feeding and discharging channels of the multi-arch tunnel are provided in advance, so as to optimize the construction procedure and achieve the purpose of improving work efficiency.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A construction method for a self-pile-in-hole method tunnel to enter a multi-arch tunnel in advance. After the side pilot tunnel of the pile-in-hole method tunnel reaches the end, it continues to extend forward, and the extension length meets the construction space requirements of the transverse channel. Then, openings are made on the side walls of the two side pilot tunnels in opposite directions, and the transverse channel connects the openings of the two side pilot tunnels. After the surrounding soil is reinforced and the temporary structure is strengthened, the horseshoe-shaped portal of the multi-arch tunnel main line is demolished. The horseshoe-shaped portal of the multi-arch tunnel is demolished from the transverse channel, and each grid steel frame is expanded outward to the standard section of the interval multi-arch tunnel, and the upper half section of the multi-arch tunnel is excavated; the excavation of the lower half section is carried out after the second lining and arch closure of the end wall of the pile-in-hole method tunnel are completed.

[0008] The construction method of the present invention for a self-pile-in-hole method tunnel to enter a multi-arch tunnel in advance specifically includes the following steps:

[0009] Step 1: The side pilot tunnel of the pile-in-hole method tunnel continues to extend to the position of the transverse channel.

[0010] Step 2: After implementing strengthening measures, the horseshoe-shaped portals in opposite directions of the extended sections of the two side pilot tunnels of the pile-in-hole method tunnel are demolished, and the connecting transverse channel of the side pilot tunnels of the pile-in-hole method tunnel is excavated. In order to improve the excavation height of the transverse channel as much as possible, the arch springing of the connecting transverse channel adopts a circular cutting form.

[0011] Step 3: After the transverse channel itself and its surrounding area are reinforced, the horseshoe-shaped portal of the multi-arch tunnel is demolished from the transverse channel, and each grid steel frame is expanded outward to the standard section of the interval multi-arch tunnel.

[0012] Step 4: After the excavation is completed, the multi-arch tunnel is lined with a secondary lining structure from far to near, and finally the secondary lining of the multi-arch tunnel within the transverse channel range is constructed. The structure is strengthened by using steel sections near the demolished horseshoe-shaped portal.

[0013] A construction structure for a self-drilled pile method tunnel to enter a multi-arch tunnel in advance according to the present invention includes a drilled pile method tunnel and a multi-arch tunnel. The drilled pile method tunnel includes side pilot tunnels of the drilled pile method tunnel. The side pilot tunnels of the drilled pile method tunnel on both sides continue to extend beyond the position of the end cross-passage. The side pilot tunnels of the drilled pile method tunnel on both sides open horsehead portals towards each other. The horsehead portals of the side pilot tunnels of the drilled pile method tunnel are connected to the cross-passage. The drilled pile method tunnel opens a horsehead portal from the cross-passage towards the main line of the multi-arch tunnel. From the horsehead portal of the multi-arch tunnel at the cross-passage, each grid steel frame is gradually expanded outwards to the standard section of the interval multi-arch tunnel as the initial support D of the expanded multi-arch tunnel, and is gradually connected to the initial support of the standard section of the multi-arch tunnel. The second lining of the multi-arch tunnel is constructed within the scope of the cross-passage.

[0014] The arch springing of the cross-passage adopts a circular cutting form.

[0015] Effects of the invention

[0016] The present invention advances the excavation and support time of the multi-arch tunnel from after the arch closure of the drilled pile method tunnel to after the construction of the side pilot tunnels of the drilled pile method tunnel. After the side pilot tunnels of the drilled pile method are excavated forward for a certain distance, a transverse temporary passage is constructed at the end, and the horsehead portal is broken through by means of the temporary passage to excavate the multi-arch tunnel in advance. A construction passage for the multi-arch tunnel is opened in advance by using the side pilot tunnels of the drilled pile method tunnel, changing the series operation into a parallel operation, effectively improving the construction efficiency, better alleviating the contradiction between the difficulty of project land occupation and the construction period pressure, and also conforming to the concepts of green and energy conservation, with remarkable social and economic benefits and great significance. Description of the drawings

[0017] Figure 1 It is a schematic diagram of the construction structure of the drilled pile method tunnel in the prior art;

[0018] Figure 2 is a schematic diagram of the construction steps of the multi-arch tunnel in the prior art; where ① represents the No. 1 chamber, ② represents the No. 2 chamber, ③ represents the No. 3 chamber, and ④ represents the No. 4 chamber;

[0019] Figure 3 It is a schematic diagram of the interface between the drilled pile method tunnel and the multi-arch tunnel in the prior art;

[0020] Figure 4 It is a schematic diagram of the cross-section of the interval drilled pile method tunnel in the prior art;

[0021] Figure 5 It is a schematic diagram of the cross-section of the interval multi-arch tunnel in the prior art;

[0022] Figure 6 It is a schematic diagram of the interface between the drilled pile method tunnel and the multi-arch tunnel of the present invention;

[0023] Figure 7 For Figure 6 section 1-1 of

[0024] Figure 8 For Figure 7 Schematic diagram of the cross-section structure at the interface between the bored pile method tunnel and the twin-arch tunnel of the present invention;

[0025] Figure 9 For Figure 8 Cross-section diagram of the 1-1 transverse passage;

[0026] Figures 10(1)-(3) are the flowcharts of the external expansion method of the grid steel frame for the transverse passage twin-arch section of the bored pile method tunnel of the present invention; (1) is the general assembly drawing of the grid steel frame for 1-3 frames in the excavation section, (2) is the general assembly drawing of the 4th frame of the grid steel frame in the excavation section, and (3) is the general assembly drawing of the grid steel frame of the standard section.

[0027] Figure 11 Is the construction process diagram of the bored pile method tunnel and the twin-arch tunnel of the present invention; the arrows in the figure indicate the construction direction;

[0028] Description of the drawing reference numbers:

[0029] Bored pile method tunnel 1, side pilot tunnel 101 of the bored pile method tunnel, initial support inverted arch 102, side pile 103, middle pile (column) 104, temporary transverse passage 105, end wall 106 of the bored pile method tunnel, twin-arch tunnel 2, initial support 201 of the twin-arch tunnel, temporary inverted arch 202, core soil 203, secondary lining structure 204 of the twin-arch tunnel, initial support 1011 of the side pilot tunnel, deep hole grouting A of the side pilot tunnel, top of rail B, initial support of the twin-arch tunnel reverse excavation connecting to the end wall of the bored pile method tunnel C, initial support of the twin-arch tunnel in the external expansion section D, indicating that the initial support of each frame of the grid steel frame is gradually externally expanded to the standard section, circumferential support E of the transverse passage, closed construction 22a steel support F, erected before breaking the horsehead portal, center line G of the interval line, interval transition section H, extension K of the side pilot tunnel, initial support 201a of the end channel entering the tunnel, progressive external expansion 201b of the initial support of the twin-arch tunnel, initial support 201c of the standard section of the twin-arch tunnel. Detailed implementation method

[0030] Refer to Figure 6 As shown, a construction method for the twin-arch tunnel to enter from the bored pile method tunnel in advance of the present invention is to continue extending the side pilot tunnel 101 of the bored pile method tunnel forward after reaching the end, and the extension length meets the construction space requirements of the temporary transverse passage 105. Then, openings are made on the side walls of the two side pilot tunnels 101 in opposite directions and connected to the transverse passage 105. After the surrounding soil is reinforced and the temporary structure is strengthened, the horsehead portal of the twin-arch tunnel main line is broken from the transverse passage 105, and the upper half section of the twin-arch tunnel 2 is excavated; the excavation of the lower half section is carried out after the secondary lining inverted arch of the end wall 106 of the bored pile method tunnel is completed.

[0031] A construction method for the twin-arch tunnel to enter from the bored pile method tunnel in advance of the present invention specifically includes the following steps: See Figure 6 , Figure 11The arrow indicates the construction direction;

[0032] Step 1: The side pilot tunnel 101 of the bored pile method tunnel continues to extend to the position of the end cross passage 105.

[0033] Step 2: After implementing the strengthening measures, the opposite horseshoe-shaped portals of the side pilot tunnels 101 of the bored pile method tunnel on both sides are demolished, and the connecting cross passage 105 of the side pilot tunnels 101 of the bored pile method tunnel is excavated. In order to increase the excavation height of the cross passage as much as possible, the arch springing of the connecting cross passage adopts a circular segment form, as shown in Figure 7 、 9 ;

[0034] Step 3: After strengthening the temporary cross passage 105 itself and its surrounding area, the horseshoe-shaped portal of the connected-arch tunnel is demolished, and the lattice girder is gradually expanded outward to the standard section of the interval connected-arch tunnel one by one. As shown in Figure 6 、 11 The primary support in the middle gradually expands outward to form the primary support D of the extended-section connected-arch tunnel with the standard section. Figure 7 Starting from the horseshoe-shaped portal of the connected-arch tunnel in the cross passage 105, the lattice girder is gradually expanded outward to the standard section of the interval connected-arch tunnel to connect with the primary support 201 of the connected-arch tunnel. Figure 10(1) - Figure 10(3) The sectional view of the lattice girder expanding from section 201a to section 201c one by one;

[0035] Step 4: After the excavation is completed, the connected-arch tunnel is lined with the secondary lining structure from far to near (towards the cross passage direction), and finally the secondary lining of the connected-arch tunnel within the range of the end cross passage is constructed. The structure is strengthened by using steel sections near the demolished horseshoe-shaped portals.

[0036] See Figure 6 、 8 As shown, a construction structure for the early entry of a bored pile method tunnel into a connected-arch tunnel according to the present invention includes a bored pile method tunnel 1 and a connected-arch tunnel 2. The bored pile method tunnel includes a side pilot tunnel 101 of the bored pile method tunnel; the side pilot tunnels 101 on both sides continue to extend beyond the position of the end cross passage 105 to meet the construction space requirements of the transverse passage. The opposite horseshoe-shaped portals are opened at the extended sections of the side pilot tunnels 101 of the bored pile method tunnel on both sides to connect the cross passage. The bored pile method tunnel opens a horseshoe-shaped portal from the cross passage to the main line of the connected-arch tunnel 2. Starting from the horseshoe-shaped portal of the connected-arch tunnel in the cross passage, the lattice girder is gradually expanded outward to the standard section of the interval connected-arch tunnel to serve as the primary support D of the extended-section connected-arch tunnel, and is gradually connected to the primary support 201 of the standard-section connected-arch tunnel; the secondary lining of the connected-arch tunnel is constructed within the range of the cross passage.

[0037] Preferably, the arch springing of the cross passage adopts a circular segment form.

[0038] The present invention is further described as follows:

[0039] 1. Continue to extend the side pilot tunnel of the bored pile method tunnel. The side pilot tunnel can be finely adjusted according to the size requirements of the connected-arch tunnel. During the demolition

[0040] Adopt traditional construction methods to perform auxiliary measures such as structural strengthening and surrounding soil reinforcement near the horsehead portal.

[0041] 2. Set up a construction cross-passage at an appropriate position near the end of the adjacent pilot-tunnel method tunnel to meet the needs of constructing the connected-arch tunnel, as well as the entry of muck, equipment, and materials. Adopt traditional construction methods to perform auxiliary measures such as structural strengthening and surrounding soil reinforcement near the horsehead portal breaking area.

[0042] In the construction method of connecting a pilot-tunnel method tunnel with a connected-arch tunnel according to the present invention, after the side pilot-tunnel of the pilot-tunnel method tunnel reaches the end, it continues to extend forward, and the extension length meets the construction space requirements of the transverse passage and the side piles of the pilot-tunnel method. Then, openings are made on the side walls of the side pilot-tunnels, and the transverse passage connects the openings of the two side pilot-tunnels. The clear dimension of the transverse passage meets the construction needs of entering the connected-arch tunnel. After the surrounding soil reinforcement and temporary structure strengthening are completed according to the traditional construction method, the horsehead portal of the main line of the connected-arch tunnel is demolished, and the upper half-section excavation of the connected-arch tunnel is carried out. The excavation of the lower half-section is carried out after the second lining and arch closure of the end wall of the pilot-tunnel method tunnel are completed.

[0043] The use of the upper half-section can complete the soil reinforcement and groundwater treatment of the lower half-section in advance.

[0044] To address the problems of complex force transfer and high engineering risks existing in the horsehead portal breaking of the side pilot-tunnel of the pilot-tunnel method tunnel and the horsehead portal breaking of the transverse passage, the structures are strengthened by using steel sections according to the traditional construction method near the horsehead portal breaking area.

[0045] The construction method of the present invention has been applied in the second phase (western extension) project of a certain airport line, and the excavation of the initial support structure of the connected-arch tunnel has been advanced by about 6 months. During the construction process, a shaft transverse passage (which needs to be used as the construction operation space of the connected-arch tunnel) has also been cancelled, and finally, the project investment has been saved by about 4 million yuan.

[0046] In this project, the excavation and support time of the connected-arch tunnel is advanced from after the arch closure of the pilot-tunnel method tunnel to after the construction of the upper pilot-tunnel is completed. After the pilot-tunnel of the pilot-tunnel method is excavated forward for a certain distance, a transverse temporary passage is constructed at the end, and the horsehead portal is demolished with the help of the temporary passage to excavate the connected-arch tunnel in advance.

[0047] The main construction procedures of the side pilot-tunnel, transverse passage, and connected-arch tunnel of the pilot-tunnel method tunnel are divided into the following steps:

[0048] 1. The side pilot-tunnel of the pilot-tunnel method tunnel continues to extend to the position of the transverse passage.

[0049] 2. Implement strengthening measures, demolish the horsehead portal of the small pilot-tunnel, and excavate the connecting transverse passage of the side pilot-tunnel of the pilot-tunnel method tunnel. In order to increase the excavation height of the transverse passage as much as possible, the arch springing of the connecting transverse passage adopts a circular segment form.

[0050] 3. Strengthen the cross passage itself and its surroundings, remove the horse head gate of the linked arch tunnel, and expand the grid steel frames one by one to the standard section of the section.

[0051] 4. After the excavation is completed, the second lining structure of the joint arch tunnel is constructed from far to near, and finally the second lining of the joint arch tunnel within the cross channel is constructed.

[0052] The construction steps of the joint arch tunnel are as follows: See Figure 2 (1)-(8)

[0053] 1. Use cement-water-glass double-liquid deep hole grouting to improve the soil within 3m of the outer skin of the left line guide tunnel's primary support. Use the core soil to excavate the 1# cavern, drive the locking anchor rods, and promptly erect the grid steel frame and temporary invert arch to close the ring and perform grouting behind the primary support (5m away from the excavation surface). See Figure 2 (1)

[0054] 2: When the 1# cavern is about 6 to 10 meters ahead, the 2# cavern is fully excavated, the initial support steel frame is promptly closed and back grouting is carried out (5 meters away from the excavation surface). See Figure 2 (2)

[0055] 3: Use cement-water-glass double-liquid deep hole grouting to improve the unreinforced soil within 3m of the outer skin of the primary support of the right line guide tunnel. Use the core soil to excavate the 3# cavern (the distance between the left and right line excavation faces is ≥20m), drive the locking anchor rods, and promptly erect the grid steel frame and temporary invert arch to close the ring and perform grouting behind the primary support. See Figure 2 (3)

[0056] 4: When the 3# cavern is about 6 to 10 meters ahead, the 4# cavern is fully excavated, the initial support steel frame is promptly closed and back grouting is performed. See Figure 2 (4)

[0057] 5: After the left line primary branch is connected, the left line cavern inverted arch waterproof layer and secondary lining structure are constructed. See Figure 2 (5)

[0058] 6: According to the monitoring and measurement data, the temporary arches of the 1# and 2# caverns are removed, and the removal length is not more than 6m (the specific length is determined according to the on-site monitoring and measurement), and the waterproof layer and secondary lining structure of the left-line tunnel side wall and top arch are constructed. See Figure 2 (6)

[0059] 7: After the right line primary support is connected, the right line cavern inverted arch waterproof layer and secondary lining structure are constructed. See Figure 2 (7)

[0060] 8: According to the monitoring and measurement data, the temporary supports of the 3# and 4# caverns are removed, with the removal length not exceeding 6m (the specific length is determined based on the on-site monitoring and measurement), and the waterproof layer and secondary lining structure of the right-line tunnel side wall and top arch are constructed. See Figure 2(8).

Claims

1. A construction method for a self-drilling and pile method tunnel to enter a multi-arch tunnel in advance, characterized in that, After the side pilot tunnels of the tunnel constructed by the pilot - hole - pile method reach the end, they continue to extend forward, and the extension length meets the construction space requirements of the transverse passage. Then, openings are made on the side walls of the side pilot tunnels on both sides in opposite directions, and the transverse passage connects the openings of the side pilot tunnels on both sides. After the surrounding soil is reinforced and the temporary structure is strengthened, the portal of the main line of the multi - arch tunnel is demolished. The portal of the multi - arch tunnel is demolished from the transverse passage, and each grid steel frame is expanded outward to the standard section of the multi - arch tunnel in the interval. Then, the upper half - section of the multi - arch tunnel is excavated; the excavation of the lower half - section is carried out after the second - lining and arch - buckling of the end - wall of the tunnel constructed by the pilot - hole - pile method are completed.

2. The construction method for the self-drilling pile method tunnel to enter the connected-arch tunnel in advance as described in claim 1, characterized in that, Specifically, it includes the following steps: Step 1: The side pilot tunnels of the tunnel constructed by the pilot - hole - pile method continue to extend to the position of the transverse passage; Step 2: After implementing strengthening measures, the opposite - direction portals of the extended sections of the side pilot tunnels of the tunnel constructed by the pilot - hole - pile method on both sides are demolished, and the connecting transverse passage of the side pilot tunnels of the tunnel constructed by the pilot - hole - pile method is excavated. In order to increase the excavation height of the transverse passage as much as possible, the arch springing of the connecting transverse passage adopts a circular - segment form; Step 3: After the transverse passage itself and its surrounding area are reinforced, the portal of the multi - arch tunnel is demolished from the transverse passage, and each grid steel frame is expanded outward to the standard section of the multi - arch tunnel in the interval; Step 4: After the excavation is completed, the multi - arch tunnel is lined with a secondary lining structure from far to near. Finally, the secondary lining of the multi - arch tunnel within the transverse passage is constructed, and the structure is strengthened with profiled steel near the portal demolition area.

3. The construction structure for the early entry of the self-drilling and pile method tunnel into the multi-arch tunnel according to claim 1, comprising a self-drilling and pile method tunnel (1) and a multi-arch tunnel (2), wherein the self-drilling and pile method tunnel includes a side pilot tunnel (101) of the self-drilling and pile method tunnel; characterized in that, The side pilot tunnels (101) of the tunnel constructed by the pilot - hole - pile method on both sides continue to extend beyond the position of the transverse passage (105). Opposite - direction portals are opened in the side pilot tunnels on both sides. The portals of the side pilot tunnels of the tunnel constructed by the pilot - hole - pile method are connected to the transverse passage. The side pilot tunnels of the tunnel constructed by the pilot - hole - pile method open portals from the transverse passage to the main line of the multi - arch tunnel (2). Each grid steel frame (5) is expanded outward from the portal of the multi - arch tunnel at the transverse passage to the standard section of the multi - arch tunnel in the interval as the primary support D of the extended - section multi - arch tunnel, and is gradually connected to the primary support (201) of the standard - section multi - arch tunnel. The secondary lining of the multi - arch tunnel is constructed within the transverse passage.

4. The construction structure according to claim 3, characterized in that, The arch springing of the transverse passage adopts a circular - segment form.

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