Advanced support system for existing building under-crossing tunnel and shock-absorbing blasting construction method

Abstract

The present invention discloses an advanced support system for under-passing tunnels in existing buildings and a shock-absorbing blasting construction method, belonging to the technical field of building tunnel construction. The method includes: First, build a shock-absorbing advanced support system for the tunnel; then excavate a blasting pilot tunnel and arrange blast holes; arrange peripheral blasting holes and shock-absorbing holes; arrange auxiliary blasting holes; and finally conduct overall blasting. The excavation of the blasting pilot tunnel, arrangement of blast holes, arrangement of peripheral blasting holes and shock-absorbing holes, arrangement of auxiliary blasting holes, and overall blasting are carried out in sequence in the upper right pilot tunnel, lower right pilot tunnel, upper left pilot tunnel, lower left pilot tunnel, middle upper pilot tunnel, and middle lower pilot tunnel of the tunnel according to the spatial order. The present invention can effectively reduce the vibration generated during the blasting process, thereby reducing the impact on the existing buildings on the upper layer.

Description

Technical Field

[0001] The present invention relates to the technical field of construction tunnel construction, and particularly relates to an advanced support system for an existing building to pass under a tunnel and a shock-absorbing blasting construction method. Background Art

[0002] With the rapid development of urban traffic construction, the traffic flow in urban roads has gradually increased. To meet the traffic demand, reduce the line mileage, and at the same time not affect the urban landscape, in the prior art, tunnels are usually built to cross the obstacles on the line. Among them, the urban arterial tunnel is usually designed as a large-section tunnel with multiple lanes to improve the road traffic capacity to meet the traffic flow needs.

[0003] Blasting excavation and advanced pipe shed reinforcement are relatively common methods in the construction of large-section tunnels. However, when building a tunnel passing under an existing building in the city, problems such as disturbance during the close-range underpass blasting construction between the newly built tunnel and the existing building are often faced. Conventional advanced reinforcement measures and bench cut blasting can no longer meet the requirements of the key and difficult construction sections, especially the shock-absorbing measures in the blasting construction of large-section tunnels passing under buildings. If there is a slight mistake, it will not only bring problems to the tunnel construction, but also seriously threaten and damage the lives and property of the people. Summary of the Invention

[0004] To solve the above problems, the present invention provides a shock-absorbing blasting construction method for an existing building to pass under a tunnel. The method includes:

[0005] First, build a tunnel shock-absorbing advanced support system; then excavate a blasting pilot tunnel and arrange blast holes; arrange peripheral blast holes and shock-absorbing holes; arrange auxiliary blast holes; and finally conduct overall blasting;

[0006] The excavation of the blasting pilot tunnel, arrangement of blast holes, arrangement of peripheral blast holes and shock-absorbing holes, arrangement of auxiliary blast holes, and overall blasting are carried out in sequence according to the spatial order in the upper right pilot tunnel, lower right pilot tunnel, upper left pilot tunnel, lower left pilot tunnel, middle upper pilot tunnel, and middle lower pilot tunnel of the tunnel.

[0007] Optionally, the excavation of the blasting pilot tunnel and arrangement of blast holes include: excavating a pilot tunnel in the middle and lower parts of the upper right pilot tunnel, lower right pilot tunnel, upper left pilot tunnel, and lower left pilot tunnel, and the pilot tunnel is a blasting pilot tunnel; digging holes at the top and sides along the boundary line of the blasting pilot tunnel, and the holes are blast holes for loading explosives for blasting;

[0008] The arrangement of peripheral blast holes and shock-absorbing holes includes: drilling holes along the dividing line of the upper right pilot tunnel, lower right pilot tunnel, upper left pilot tunnel, lower left pilot tunnel, and upper right pilot tunnel, and selecting some of the drilled holes to load explosives as peripheral blast holes, and the drilled holes without loading explosives as shock-absorbing holes.

[0009] Optionally, among the upper right pilot tunnel, the lower right pilot tunnel, the upper left pilot tunnel, and the lower left pilot tunnel, the drill holes distributed along the boundary line are in two layers;

[0010] Among them, the drill holes in the layer closer to the boundary line are the outer-layer drill holes, and the other layer of drill holes is the inner-layer drill holes; the shock-absorbing holes and the surrounding blast holes in the outer-layer drill holes and the inner-layer drill holes are arranged at intervals alternately;

[0011] The surrounding blast holes and the shock-absorbing holes provided on the middle upper pilot tunnel are in one layer and are arranged at intervals in sequence.

[0012] Optionally, the surrounding blast holes and the shock-absorbing holes arranged in the upper right pilot tunnel and the upper left pilot tunnel are located on both sides and the top of the upper right pilot tunnel and the upper left pilot tunnel;

[0013] The surrounding blast holes and the shock-absorbing holes arranged in the lower right pilot tunnel and the lower left pilot tunnel are located on both sides of the lower right pilot tunnel and the lower left pilot tunnel.

[0014] Optionally, arranging the auxiliary blast holes includes: drilling holes and filling explosives in the upper right pilot tunnel, the lower right pilot tunnel, the upper left pilot tunnel, the lower left pilot tunnel, the middle upper pilot tunnel, and the middle lower pilot tunnel as the auxiliary blast holes;

[0015] Optionally, the arrangement method of the auxiliary blast holes is a combination of a straight line shape and an arc shape;

[0016] Among them, the spacing and row spacing between the auxiliary blast holes are greater than those of the surrounding blast holes and greater than the minimum resistance line;

[0017] Optionally, in the upper right pilot tunnel and the upper left pilot tunnel, the auxiliary blast holes close to the inner-layer drill holes are distributed in an arc shape;

[0018] The auxiliary blast holes located in the middle upper pilot tunnel are distributed in layers;

[0019] Among them, the auxiliary blast holes in the topmost layer in the middle upper pilot tunnel are arranged in an arc, and the auxiliary blast holes below are arranged in a straight line;

[0020] The auxiliary blast holes located in the middle lower pilot tunnel are arranged in a straight line.

[0021] Optionally, the overall blasting includes using millisecond delay initiation for overall blasting;

[0022] Among them, the length of the advance of the overall blasting is 1.5 - 1.8 m. After the overall blasting, the initial support and the temporary support should be constructed.

[0023] Optionally, a pre-support system for the existing building undercrossing tunnel blasting shock absorption construction method described in any one of the above schemes, the pre-support system includes a non-working chamber advanced steel pipe shed and advanced shock-absorbing small pipes arranged in the soil layer;

[0024] The above-mentioned working chamber advanced steel pipe shed includes a first advanced steel pipe, a detachable connection member detachably connected to the first advanced steel pipe, a second advanced steel pipe detachably connected to the detachable connection member, and an auxiliary installation pipe detachably connected to the second advanced steel pipe;

[0025] Among them, the first advanced steel pipe is a hollow tubular structure with a pointed end and an open end, and its hollow part is the first grouting channel; a first external thread is also provided on the outer periphery of the open end of the first advanced steel pipe.

[0026] The detachable connection member is a hollow tubular structure, and its hollow part is the second grouting channel. Among them, a stop screw protrusion is provided in the middle of the inner wall of the detachable connection member, and internal threads are provided on both sides of the stop screw protrusion;

[0027] The second advanced steel pipe is a hollow tubular structure, and its hollow part is the third grouting channel. Among them, a second external thread is provided on the outer periphery of the open end of one end of the second advanced steel pipe, and a plurality of notches are provided at the open end of the other end, and the notches are clamping grooves;

[0028] Among them, the second external thread, the first external thread and the internal thread are adapted to each other; a plurality of through holes penetrating the pipe wall are also provided on the first advanced steel pipe and the second advanced steel pipe, and among them, the through holes are the first grouting holes;

[0029] One end of the auxiliary installation pipe is provided with a protrusion, and the protrusion is a clamping part, and among them, the clamping part is adapted to the clamping groove;

[0030] A protruding pushing connecting piece is provided at the other end of the auxiliary installation pipe;

[0031] A conical protrusion is provided on the inner wall of the first grouting channel near the pointed end of the first advanced steel pipe, and the conical protrusion is a barb for fixing the steel reinforcement cage for grouting;

[0032] The advanced shock-absorbing small pipe is a hollow tubular structure with a pointed end and an open end, and its hollow part is the fourth grouting channel;

[0033] A plurality of through holes penetrating the pipe wall are provided on the advanced shock-absorbing small pipe, and the through holes on the advanced shock-absorbing small pipe are the second grouting holes.

[0034] Optionally, the lengths of the first advanced steel pipe and the second advanced steel pipe are 5-6m;

[0035] The external insertion angles of the first advanced steel pipe and the second advanced steel pipe arranged in the soil layer are 10-15°;

[0036] When building an advanced steel pipe shed without a working chamber in the soil layer, it is arranged every 6-7m;

[0037] The length of the advanced shock-absorbing small duct is 6 - 8 m, the external insertion angle into the soil layer is 5 - 8°, and it is arranged every 3 - 4 m;

[0038] The grouting slurry injected into the advanced shock-absorbing small duct is modified CA mortar;

[0039] Among them, the modified CA mortar is ordinary CA mortar added with 7.5% mica powder and 10% rubber powder.

[0040] By adopting the above technical solutions, the present invention mainly has the following technical effects:

[0041] 1. During the blasting construction process, by setting upper right, lower right, upper left, lower left, middle upper, and middle lower pilot tunnels in the tunnel and blasting them one by one in sequence, the single blasting volume can be reduced, thereby reducing the vibration generated during a single blasting and reducing the impact on the existing buildings above.

[0042] 2. By arranging two layers of staggered shock-absorbing holes and peripheral blast holes at the boundaries of the pilot tunnels, during blasting, on the one hand, the arrangement of explosives can be dispersed, and on the other hand, more obstacles can be set on the propagation path of the blasting vibration wave, further weakening the propagation of the blasting vibration wave and enhancing the shock-absorbing effect. At the same time, due to the use of the millisecond delay initiation technology, the vibration waves generated by the blasting of the peripheral blast holes filled with explosives between the two layers of shock-absorbing holes will be staggered due to mutual interference or the inability to superimpose the peak values, resulting in a significant reduction in the maximum vibration peak generated by the explosion, thereby further reducing the vibration generated during the blasting and reducing the impact on the existing buildings above.

[0043] 3. By adopting a combination of linear and arc-shaped methods to set the auxiliary blast holes and using the millisecond delay initiation technology at the same time, the vibration waves generated in the direction of the connection line of the auxiliary blast holes cancel each other out, and the vibration waves perpendicular to the connection line direction are only transmitted on the rock mass near the auxiliary blast holes, thereby reducing the impact on the existing buildings above during blasting.

[0044] 4. When blasting the upper pilot tunnel and the middle lower pilot tunnel, instead of using the method of excavating the blasting pilot tunnel and arranging blast holes for overall blasting, a layer of peripherally spaced blast holes and shock-absorbing holes is set in the upper middle pilot tunnel, and auxiliary blast holes are arranged in the upper middle pilot tunnel and the middle lower pilot tunnel for overall blasting. On the one hand, it can meet the blasting requirements, and on the other hand, it can reduce the vibration generated by blasting by reducing the amount of explosive loaded, further reducing the impact on the existing buildings.

[0045] 5. By building a tunnel shock-absorbing advanced support system and setting up advanced shock-absorbing small ducts, two layers of shock-absorbing grouting layers are formed directly above each tunnel pilot drift before excavation. The two layers of shock-absorbing grouting layers are located on the propagation path of vibration from the blasting position to the upper building, reducing the impact of vibration generated during blasting on the existing upper building.

[0046] 6. By using modified CA mortar as the grouting slurry injected into the advanced shock-absorbing small ducts, compared with ordinary CA mortar, 7.5% mica powder and 10% rubber powder are added, increasing the damping high characteristics of the slurry and further reducing the impact of vibration generated during blasting on the existing upper building. Description of the Drawings

[0047] Figure 1 It is a schematic structural diagram of the tunnel construction surface in a blasting shock-absorbing construction method for a tunnel underpassing an existing building according to the present invention;

[0048] Figure 2 It is a schematic structural diagram of the tunnel construction surface (from another perspective) in a blasting shock-absorbing construction method for a tunnel underpassing an existing building according to the present invention;

[0049] Figure 3 It is a schematic structural diagram during the construction of the upper right pilot drift in a blasting shock-absorbing construction method for a tunnel underpassing an existing building according to the present invention;

[0050] Figure 4 It is a schematic structural diagram of a tunnel shock-absorbing advanced support system according to the present invention;

[0051] Figure 5 It is a schematic structural diagram of the first advanced steel pipe in a tunnel shock-absorbing advanced support system according to the present invention;

[0052] Figure 6 It is a schematic structural diagram of a detachable connection member in a tunnel shock-absorbing advanced support system according to the present invention;

[0053] Figure 7 It is a schematic structural diagram of the second advanced steel pipe in a tunnel shock-absorbing advanced support system according to the present invention;

[0054] Figure 8 It is a schematic structural diagram of an auxiliary installation pipe in a tunnel shock-absorbing advanced support system according to the present invention;

[0055] Figure 9 It is a schematic structural diagram of an advanced shock-absorbing small duct in a tunnel shock-absorbing advanced support system according to the present invention;

[0056] Figure 10 It is a schematic structural diagram during the construction of the upper right pilot drift in a blasting shock-absorbing construction method for a tunnel underpassing an existing building according to the present invention;

[0057] Figure 11It is a schematic structural diagram during the construction of the lower right pilot tunnel in the blasting shock absorption construction method for an existing building passing under a tunnel according to the present invention;

[0058] Figure 12 It is a schematic structural diagram during the construction of the upper left pilot tunnel in the blasting shock absorption construction method for an existing building passing under a tunnel according to the present invention;

[0059] Figure 13 It is a schematic structural diagram during the construction of the lower left pilot tunnel in the blasting shock absorption construction method for an existing building passing under a tunnel according to the present invention;

[0060] Figure 14 It is a schematic structural diagram during the construction of the upper and middle - lower pilot tunnels in the blasting shock absorption construction method for an existing building passing under a tunnel according to the present invention;

[0061] Figure 15 It is a schematic structural diagram of applying support in the blasting shock absorption construction method for an existing building passing under a tunnel according to the present invention.

[0062] Among them, the meanings of the reference numerals are as follows:

[0063] 1. Advance steel pipe shed without working chamber; 11. First advance steel pipe; 111. First grouting channel; 112. First external thread; 113. First grouting hole; 114. Barbed part; 12. Detachable connection member; 121. Second grouting channel; 122. Anti - spiral protrusion; 123. Internal thread; 13. Second advance steel pipe; 131. Third grouting channel; 132. Second external thread; 133. Clamping groove; 14. Auxiliary installation pipe; 141. Clamping part; 142. Thrust connecting part;

[0064] 2. Advance shock - absorbing small duct; 21. Fourth grouting channel; 22. Second grouting hole;

[0065] 3. Tunnel construction surface; 31. Upper right pilot tunnel; 32. Lower right pilot tunnel; 33. Upper left pilot tunnel; 34. Lower left pilot tunnel; 35. Middle - upper pilot tunnel; 36. Middle - lower pilot tunnel; 37. Blasting pilot tunnel; 38. Blasthole;

[0066] 4. Borehole; 41. Peripheral explosion hole; 42. Shock - absorbing hole; 43. Auxiliary blasting hole;

[0067] A. Hole without explosive charge; B. Hole with explosive charge. Detailed implementation manners

[0068] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0069] As used herein, the phrase "embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present invention. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0070] Please refer to Figures 1-15 , a tunnel shock-absorbing advanced support system is provided in the first aspect of the present invention. When the shock-absorbing advanced support system is actually applied, it is arranged in the tunnel soil layer of blasting construction, and it includes an advanced steel pipe shed 1 without a working chamber arranged in the soil layer and an advanced shock-absorbing small conduit 2.

[0071] Please further refer to Figures 2-8 , the advanced steel pipe shed of the working chamber includes a first advanced steel pipe 11, a detachable connection member 12 detachably connected to the first advanced steel pipe 11, a second advanced steel pipe 13 detachably connected to the detachable connection member 12, and an auxiliary installation pipe 14 detachably connected to the second advanced steel pipe 3.

[0072] Furthermore, the first advanced steel pipe 11 is a hollow tubular structure with a pointed end at one end and an opening at the other end. The hollow part thereof is a first grouting flow channel 111. The advanced steel pipe shed without a working chamber can be inserted into the soil layer by inserting the pointed end of the first advanced steel pipe 1 into the soil layer. In addition, in order to detachably connect the first advanced steel pipe 11 to the detachable connection member 12, a first external thread 112 is provided on the outer periphery of the opening end of the first advanced steel pipe 11.

[0073] Furthermore, the detachable connection member 12 is a hollow tubular structure, and the hollow part thereof is a second grouting flow channel 121. The detachable connection member 12 is used to connect the first advanced steel pipe 11 and the second advanced steel pipe 13. Among them, a stop spiral protrusion 122 is provided in the middle of the inner wall of the detachable connection member 12, and internal threads 123 are provided on both sides of the stop spiral protrusion 122. Among them, the internal thread 123 is adapted to the first external thread 112, so as to connect one end of the detachable connection member 12 to the first advanced steel pipe 11 and make them internally communicate.

[0074] Furthermore, the second advanced steel pipe 13 is a hollow tubular structure, and its hollow part is the third grouting channel 131. Among them, on the outer periphery of the opening at one end of the second advanced steel pipe 13, there is a second external thread 132 adapted to the internal thread 123, so as to connect one end of the second advanced steel pipe 13 to the end of the detachable connection member 12 far from the first advanced steel pipe 11 and make them internally connected; in addition, at the opening of the other end of the second advanced steel pipe 3, there are a plurality of serrated notches, and the notches are clamping grooves 133, and the clamping grooves 133 are used to connect the second advanced steel pipe 3 to the auxiliary installation pipe 14.

[0075] A plurality of through holes penetrating the pipe wall are also provided on the first advanced steel pipe 11 and the second advanced steel pipe 12. Among them, the through holes are the first grouting holes 113 (for the process during subsequent tunnel construction).

[0076] Specifically, one end of the auxiliary installation pipe 14 is provided with a plurality of serrated protrusions, and the protrusions are clamping parts 141. Among them, the clamping parts 141 are adapted to the clamping grooves 133, and the auxiliary installation pipe 14 can be detachably connected to the second advanced steel pipe 13 by clamping the clamping parts 141 with the clamping grooves 133. In addition, a regular hexagon protrusion is provided on the other end of the auxiliary installation pipe 14, and the protrusion is a pushing connecting part 142, which is used to detachably connect the auxiliary installation pipe 14 to the pushing device, and the first advanced steel pipe 11, the detachable connection member 12 and the second advanced steel pipe 13 are sent into the soil layer through the pushing device.

[0077] After the first advanced steel pipe 11, the detachable connection member 12 and the second advanced steel pipe 13 are sent into the soil layer, in order to grout the advanced steel pipe shed 1 without a working chamber, a conical protrusion is provided on the inner wall near the pointed end of the first advanced steel pipe 11 in the first grouting channel, and the conical protrusion is an inverted hook part 114. By providing the inverted hook part 14, when the operator grouts the advanced steel pipe shed 1 without a working chamber through the steel reinforcement cage, the steel reinforcement cage is first sent into the second advanced steel pipe 13, and the steel reinforcement cage enters the first grouting channel 111 through the third grouting channel 131 and the second grouting channel 121 in sequence. When the steel reinforcement cage passes near the inverted hook part 114, since the opening in the first grouting channel 111 gradually decreases first and then suddenly increases, the steel reinforcement cage passing through the inverted hook part 114 is clamped on the inverted hook part 114, thus completing the grouting.

[0078] Furthermore, please refer to Figures 2-9 , the advanced shock-absorbing small pipe 2 is a hollow tubular structure with a pointed end at one end and an opening at the other end, and its hollow part is the fourth grouting channel 21. The advanced shock-absorbing small pipe 2 can be sent into the soil layer by inserting the pointed end of the advanced shock-absorbing small pipe 2 into the soil layer.

[0079] The advanced shock-absorbing small duct is provided with a plurality of through holes 21 penetrating the pipe wall, wherein the through holes on the advanced shock-absorbing small duct are the second grouting holes 22.

[0080] Please refer to Figures 1-9 , the second aspect of the present invention provides a construction method for blasting shock absorption of an existing building passing under a tunnel. Specifically, the main steps of the construction method of the present invention are as follows:

[0081] (a) Build a tunnel shock-absorbing advanced support system;

[0082] In this step, to build the tunnel shock-absorbing advanced support system described in the above solution in the soil layer of the tunnel, it includes building an advanced steel pipe shed without a working chamber and setting up advanced shock-absorbing small ducts;

[0083] Specifically, building an advanced steel pipe shed without a working chamber includes: building an operating platform and fixing a drilling rig, then drilling holes in the soil layer, then sending the first advanced steel pipe 11, detachable connecting members 12, and the second advanced steel pipe 13 into the soil layer, and finally fixing the steel reinforcement cage in the first advanced steel pipe 11 and the second advanced steel pipe 13 and then grouting.

[0084] In a preferred embodiment, the lengths of the first advanced steel pipe 11 and the second advanced steel pipe 13 are 5 - 6m, that is, the sum of the lengths of the first advanced steel pipe 11 and the second advanced steel pipe 13 is 10 - 12m; the external insertion angle (the angle between the steel pipe of the pipe shed and the longitudinal direction of the tunnel) of the first advanced steel pipe 11 and the second advanced steel pipe 13 arranged in the soil layer is 10 - 15°.

[0085] In a more preferred embodiment, when building an advanced steel pipe shed without a working chamber in the soil layer, it should be rearranged every 6 - 7m.

[0086] Setting up the advanced shock-absorbing small duct includes: inserting the advanced shock-absorbing small duct 2 into the soil layer, and after the arrangement is completed, injecting slurry into the advanced shock-absorbing small duct 2.

[0087] In a preferred embodiment, the length of the advanced shock-absorbing small duct 2 is 6 - 8m, the external insertion angle (the angle between the steel pipe of the pipe shed and the longitudinal direction of the tunnel (the direction in which the center lines of the tunnel at each mileage are connected along the tunnel alignment is the longitudinal direction of the tunnel)) when inserted into the soil layer is 5 - 8°, and it is arranged every 3 - 4m, so that before the excavation of each tunnel pilot tunnel, two layers of shock-absorbing grouting layers are formed directly above it, and the two layers of shock-absorbing grouting layers are on the propagation path of the vibration from the blasting position to the upper building, thereby reducing the impact of the vibration generated during blasting on the upper existing building.

[0088] In a more preferred embodiment, the grouting slurry injected into the advanced shock-absorbing small ducts 2 is modified CA mortar. Compared with ordinary CA mortar, 7.5% mica powder and 10% rubber powder are added, which increases the damping high characteristics of the slurry and further reduces the impact of the vibration generated during blasting on the existing buildings above.

[0089] (b) Excavate the blasting drift and arrange the blast holes;

[0090] In this step, it is to excavate the blasting drift in the tunnel construction face and arrange the blast holes on the blasting drift.

[0091] Please further refer to Figure 1 , Figure 1 , which is a schematic structural diagram of the tunnel construction face 3. It includes the upper right drift 31, the lower right drift 32, the upper left drift 33, the lower left drift 34, the middle upper drift 35 and the middle lower drift 36 distributed in a spatial order. The above-mentioned excavation of the blasting drift and arrangement of the blast holes are first carried out in the upper right drift 31.

[0092] During the blasting construction process, by setting the upper right, lower right, upper left, lower left, middle upper and middle lower drifts and blasting them one by one in sequence, the single blasting volume can be reduced, thereby reducing the vibration generated during a single blasting and reducing the impact on the existing buildings above.

[0093] The process of excavating the blasting drift includes excavating a horseshoe-shaped drift in the middle and lower part of the upper right drift 31 of the tunnel construction face. The horseshoe-shaped drift is the blasting drift 37.

[0094] By excavating the blasting drift 37, the free face in the upper right drift 31 can be increased, the blasting efficiency can be improved, and thus the amount of explosive used can be reduced. By reducing the amount of explosive used, the impact of blasting on the existing buildings above can be effectively reduced.

[0095] In a preferred embodiment, the height of the blasting drift 37 is 1.8 - 2.0 m, the width is 1.8 - 2.0 m, and the depth is 1.5 - 1.8 m.

[0096] In a more preferred embodiment, the stagger distance between the upper right drift 31 and the lower right drift 32 is 3 - 5 m.

[0097] The process of arranging the blast holes includes digging holes at the top and sides along the boundary line of the horseshoe-shaped blasting drift 37. Among them, the holes distributed along the boundary line of the horseshoe-shaped blasting drift 37 are the blast holes 38 for loading explosives for blasting.

[0098] In a preferred embodiment, the distance between adjacent blast holes 38 is 0.3 - 0.5 m.

[0099] (c) Arrange the perimeter blasting holes and shock-absorbing holes;

[0100] In this step, in order to continuously drill holes 4 along the boundary line of the upper right pilot drift 31 on the tunnel construction surface, where the number of the holes 4 is multiple groups. After the holes 4 are drilled, among the holes 4 arranged along the boundary line of the upper right drift, some of the holes 4 are filled with explosives as the perimeter blast holes 41, and the holes without explosives are used as the vibration damping holes 42. Among them, the vibration damping holes 42 and the perimeter blast holes 41 are arranged at intervals in turn;

[0101] In some embodiments of the present invention, when drilling holes along the boundary line of the upper right pilot drift 31, the holes are drilled along the boundary lines on both sides and the top of the upper right pilot drift 31.

[0102] In a preferred embodiment, when drilling holes in the upper right pilot drift 31, the holes 4 distributed along the boundary line are in two layers. Among them, the layer of holes close to the boundary line of the upper right drift is the outer layer of holes, and the other layer of holes is the inner layer of holes. The vibration damping holes 42 and the perimeter blast holes 41 in the outer layer of holes and the inner layer of holes are all arranged at intervals;

[0103] In a more preferred embodiment, the vibration damping holes 42 and the perimeter blast holes 41 in the two layers of holes are staggered. For example, when the holes in the outer layer of holes are filled with explosives as the perimeter blast holes 41, the holes in the inner layer of holes opposite to the outer layer of holes without explosives are used as the vibration damping holes 42.

[0104] By arranging two layers of staggered vibration damping holes 42 and perimeter blast holes 41, during blasting, on the one hand, the arrangement of explosives can be dispersed, and on the other hand, more obstacles can be set on the propagation path of the blasting vibration wave, further weakening the propagation of the blasting vibration wave and improving the vibration damping effect. Due to the use of the millisecond delay initiation technology (dividing the total blasting charge into multiple small explosive packages and detonating them in sequence at a certain time interval, so that the explosion energy is dispersed in time and space), the vibration waves generated by the blasting of the perimeter blast holes 41 filled with explosives between the two layers of vibration damping holes 42 will be staggered due to mutual interference or the inability to superimpose the peak values, resulting in a significant reduction in the maximum vibration peak value generated by the explosion. Thus, the vibration generated during the blasting process is further reduced, and the impact on the existing buildings above is reduced.

[0105] (d) Arrange the auxiliary blast holes;

[0106] In this step, in order to drill holes in the area outside the blast drift 37 in step (b) and inside the inner layer of holes in step (c), where the number of the holes is multiple groups, and after drilling, the holes are filled with explosives as the auxiliary blast holes 43;

[0107] In a preferred embodiment, the auxiliary blast holes 43 are arranged in a combination of straight and arc shapes. Among them, the spacing and row spacing between the auxiliary blast holes 43 are greater than those of the surrounding blast holes 41 and greater than the minimum resistance line (in engineering blasting, the shortest distance from the center or centroid of the charge to the nearest free face).

[0108] In a more preferred embodiment, in the upper right pilot tunnel 31 and the upper left pilot tunnel 33, the auxiliary blast holes 43 near the inner layer drilling holes are distributed in an arc shape.

[0109] Specifically, the arrangement of the auxiliary blast holes 43 mainly serves to break the rock mass, meet the blasting effect, and thus facilitate mucking. In addition, by arranging the auxiliary blast holes 43 in a combination of straight and arc shapes and using the millisecond delay initiation technology, the vibration waves generated in the direction of the connection line of the auxiliary blast holes 43 cancel each other out, while the vibration waves perpendicular to the connection line direction are only transmitted on the rock mass near the auxiliary blast holes 43, thereby reducing the impact on the existing buildings above during blasting.

[0110] (e) Conduct overall blasting;

[0111] In this step, in order to adopt the millisecond delay initiation technology, overall blasting is carried out in the upper right pilot tunnel 31.

[0112] In a preferred embodiment, the length of the overall blasting footage (the length opened by one blasting) is 1.5 - 1.8 m.

[0113] After overall blasting, initial support and temporary support should be constructed.

[0114] (f) Repeat steps (b) to (e)

[0115] In this step, in order to repeat the blasting methods of steps (b) to (e), the lower right pilot tunnel 32, the upper left pilot tunnel 33, and the lower left pilot tunnel 34 are blasted in sequence.

[0116] It should be clear that after blasting the pilot tunnels located in the lower part, that is, after blasting the lower right pilot tunnel 32, the lower left pilot tunnel 34, and the middle lower pilot tunnel 36, the invert part should be mechanically excavated and initial support and temporary support should be constructed.

[0117] In a preferred embodiment, the perimeter blast holes 41 and the shock-absorbing holes 42 arranged in the upper right pilot tunnel 31 and the upper left pilot tunnel 33 are located on both sides and the top of the upper right pilot tunnel 31 and the upper left pilot tunnel 34; the perimeter blast holes 41 and the shock-absorbing holes 42 arranged in the lower right pilot tunnel 32 and the lower left pilot tunnel 34 are both located on both sides of the lower right pilot tunnel 32 and the lower left pilot tunnel 34.

[0118] By blasting the upper right pilot tunnel 31, when blasting the lower right pilot tunnel 32, the upper part of the lower right pilot tunnel 32 has become a free face. Therefore, it is only necessary to arrange the perimeter blast holes 41 and the shock-absorbing holes 42 on both sides of the lower right pilot tunnel 32. Similarly, the perimeter blast holes 41 and the shock-absorbing holes 42 in the lower left pilot tunnel 34 are also located on both sides.

[0119] By reducing the amount of explosive charge, the vibration generated by blasting is reduced, thereby reducing the impact on the existing buildings above.

[0120] (g) Arrange the perimeter blast holes and the shock-absorbing holes;

[0121] In this step, in order to drill continuously along the boundary line of the top of the middle upper pilot tunnel 45 on the tunnel construction surface, after drilling is completed, among the drilled holes arranged along the boundary line of the middle upper pilot tunnel 45, some of the drilled holes filled with explosives are used as the perimeter blast holes 41, and the drilled holes not filled with explosives are used as the shock-absorbing holes 42. Among them, the setting method of the shock-absorbing holes 41 and the perimeter blast holes 42 is the same as that in step (c), and they are arranged at intervals in turn.

[0122] In a preferred embodiment, when drilling in the middle upper pilot tunnel 35, the drilled holes distributed along the boundary line are in one layer, that is, the perimeter blast holes 41 and the shock-absorbing holes 42 arranged on the middle upper pilot tunnel 35 are in one layer, and they are arranged at intervals in turn.

[0123] During the blasting process of the middle upper pilot tunnel 35, before the blasting of the middle upper pilot tunnel 35 and the middle lower pilot tunnel 36, the soil on both the left and right sides has been excavated, and there are a large number of free faces. Moreover, the soil in the middle upper pilot tunnel 35 and the middle lower pilot tunnel 36 has been disturbed during the previous blasting process, and its strength has decreased. Therefore, it is not necessary to excavate the blasting pilot tunnel 37 in the middle upper pilot tunnel 35 and the middle lower pilot tunnel 36, and arranging the blast holes 38 can achieve overall blasting, reducing the amount of explosives required for blasting.

[0124] By arranging a layer of perimeter blast holes 41 and shock-absorbing holes 42 arranged at intervals, on the one hand, it can meet the blasting requirements, and on the other hand, it can also reduce the vibration generated by the blasting of the middle upper pilot tunnel 35 by reducing the amount of explosive charge, further reducing the impact on the existing buildings.

[0125] (h) Arrange the auxiliary blast holes;

[0126] In this step, drill holes below the perimeter blast holes 41 and the shock-absorbing holes 42 in the middle upper pilot tunnel 35. Among them, the number of the drilled holes is multiple groups, and after drilling, explosives are filled as the auxiliary blast holes 43.

[0127] In a preferred embodiment, the auxiliary blast holes 43 located in the middle upper pilot tunnel 35 are distributed in layers.

[0128] In a more preferred embodiment, the auxiliary blasting holes 43 located at the uppermost layer in the middle and upper pilot pit 35 are arranged in an arc shape, and the auxiliary blasting holes located below the uppermost layer are arranged in a straight line horizontally.

[0129] (i) Carry out mass blasting;

[0130] In this step, the upper pilot pit 35 is subjected to overall blasting by adopting the micro-difference time-delay detonation technology.

[0131] In a preferred embodiment, the length of the overall blasting footage is 1.5-1.8 m.

[0132] After the overall blasting, initial support and temporary support should be implemented.

[0133] (j) Arrangement of auxiliary blasting holes;

[0134] In this step, holes are drilled in the middle and lower pilot pit 36 , wherein the number of the holes drilled is multiple groups, and after drilling, explosives are loaded as auxiliary blasting holes 43 .

[0135] In a preferred embodiment, the auxiliary blasting holes 43 located in the middle and upper pilot pit 35 are distributed in layers.

[0136] In a more preferred embodiment, the auxiliary blasting holes 43 located in the middle and lower pilot pit 36 are arranged in a straight line laterally.

[0137] Specifically, the arrangement of the auxiliary blasting holes 43 mainly plays the role of crushing the rock mass. After the middle and upper pilot pit 35 is blasted, the soil on the left and right sides and above the middle and lower pilot pit 36 has been excavated. Therefore, it is sufficient to use a straight line and horizontal arrangement of auxiliary blasting holes in the middle and lower pilot pit 36 to blast the rock mass.

[0138] (k) Carrying out mass blasting;

[0139] In this step, the middle and lower pilot pit 36 is subjected to overall blasting by adopting the micro-difference time-delay detonation technology.

[0140] In a preferred embodiment, the length of the overall blasting footage is 1.5-1.8 m;

[0141] After the blasting of the middle and lower pilot tunnel 36, the invert arch part was excavated mechanically, initial support was applied, and the temporary support was removed, and the excavation of the large section of the tunnel was completed.

[0142] (l) Repeat steps (a) to (k)

[0143] This step is to repeat steps (a) to (k) to excavate the entire tunnel. After the full-section excavation is completed, secondary lining is applied simultaneously until the tunnel is through.

[0144] Example 1

[0145] In this embodiment, the lengths of the first advanced steel pipe 11 and the second advanced steel pipe 13 are 5 m, the outer diameters are 98 mm, and the wall thicknesses are 9 mm; the length of the detachable connection member 12 is 170 mm, the outer diameter is 124 mm, and the length of the internal thread 123 is 80 mm; the length of the auxiliary installation pipe 14 is 1 m, the outer diameter is 98 mm, and the wall thickness is 9 mm.

[0146] The length of the advanced shock-absorbing small guide pipe 2 is 6 m, the outer diameter is 42 mm, and the wall thickness is 4 mm. Second grouting holes 22 with a diameter of 7 mm are arranged on the advanced shock-absorbing small guide pipe 2 in a plum blossom shape, and the stagger distance is 75 mm. Among them, there is a 1 m section at the open end of the advanced shock-absorbing small guide pipe 2 where the second grouting holes 22 are not arranged.

[0147] First, set up an operation platform in the tunnel and fix the drill rig, and use the drill rig to drill holes in the tunnel. Among them, the drilling depth is slightly greater than the sum of the lengths of the first advanced steel pipe 11 and the second advanced steel pipe 13, and the depth of the hole is 10.9 m;

[0148] Push the first advanced steel pipe 11 into the hole, and when the first external thread 112 section is outside the hole, connect it to the internal thread 123 section at one end of the detachable connection member 12, then connect the other end of the detachable connection member 12 to the second advanced steel pipe 13, and then continue to push it into the hole until the second advanced steel pipe 13 completely enters the hole;

[0149] After the clamping portion 141 on the auxiliary installation pipe 14 is clamped with the clamping groove 133 of the second advanced steel pipe 13, rotate clockwise and push the auxiliary installation pipe 14 into the hole until the first advanced steel pipe 11 reaches the top of the hole. After reaching the predetermined position, pull out the auxiliary pipe 14 outward, and then send the steel reinforcement cage into the second advanced steel pipe 13 until the steel reinforcement cage hangs upside down on the barb portion 114. After fixing the position of the steel reinforcement cage, the grouting is completed.

[0150] Arrange the advanced steel pipe shed without a working chamber within the 120° range along the tunnel top, with a spacing of 0.4 m, an external insertion angle of 10°, and arrange it once every 6 m. (During the tunnel construction process, after arranging the advanced steel pipe shed without a working chamber once, the length broken by blasting must be less than the length of the advanced steel pipe shed without a working chamber to reduce the possibility of the shock-absorbing and reinforcement effect of the advanced steel pipe shed without a working chamber failing during the construction process).

[0151] Arrange the advanced shock-absorbing small guide pipe 2 within the 120° range along the tunnel top, and stagger-drill between every two pipe sheds, with a spacing of 0.4 m, an external insertion angle of 6°, and arrange it once every 3 m. (During the tunnel construction process, after arranging the advanced shock-absorbing small guide pipe 2 once, the length broken by blasting must also be less than the length of the advanced shock-absorbing small guide pipe 2).

[0152] Then, please further refer toFigure 10 , in the middle and lower part of the upper right pilot drift 31 in the tunnel, a horseshoe-shaped blasting drift 37 with a height of 1.8 m, a width of 1.8 m and a depth of 1.5 m is excavated, and blast holes 38 are arranged along the side wall and the top of the blasting drift, and the spacing between adjacent blast holes 38 is 0.4 m. Among them, the stagger distance between the upper right pilot drift 31 and the lower right pilot drift 32 is 4 m.

[0153] On the upper right pilot drift 31, the excavation boundary line is excavated, and holes are drilled at the top and both sides on the boundary line, and two layers of staggered perimeter blast holes 41 and shock-absorbing holes 42 are arranged;

[0154] On the upper right pilot drift 31, auxiliary blast holes 43 combined with straight lines and arcs are arranged;

[0155] Using the millisecond delay initiation technology, the upper right pilot drift 31 is integrally blasted, the blasting footage is 1.5 m, and the initial support and temporary support are constructed;

[0156] Please refer further to Figure 11 , in the middle and lower part of the lower right pilot drift 32 in the tunnel, a horseshoe-shaped blasting drift 37 with a height of 1.8 m, a width of 1.8 m and a depth of 1.5 m is excavated, and blast holes 38 are arranged along the side wall and the top of the blasting drift, and the spacing between adjacent blast holes 38 is 0.4 m.

[0157] On the lower right pilot drift 32, the excavation boundary line is excavated, and holes are drilled on both sides on the boundary line, and two layers of staggered perimeter blast holes 41 and shock-absorbing holes 42 are arranged;

[0158] On the lower right pilot drift 32, auxiliary blast holes 43 combined with straight lines and arcs are arranged;

[0159] Using the millisecond delay initiation technology, the lower right pilot drift 32 is integrally blasted, the blasting footage is 1.5 m, and the invert part is mechanically excavated, and the initial support and temporary support are constructed;

[0160] Please refer further to Figure 12 , in the middle and lower part of the upper left pilot drift 33 in the tunnel, a horseshoe-shaped blasting drift 37 with a height of 1.8 m, a width of 1.8 m and a depth of 1.5 m is excavated, and blast holes 38 are arranged along the side wall and the top of the blasting drift, and the spacing between adjacent blast holes �8 is 0.4 m. Among them, the stagger distance between the upper left pilot drift 33 and the lower left pilot drift 34 is 4 m.

[0161] On the upper left pilot drift 33, the excavation boundary line is excavated, and holes are drilled at the top and both sides on the boundary line, and two layers of staggered perimeter blast holes 41 and shock-absorbing holes 42 are arranged;

[0162] On the upper left pilot drift 33, auxiliary blast holes 43 combined with straight lines and arcs are arranged;

[0163] Using the millisecond delay initiation technology, the upper left pilot drift 33 is integrally blasted, the blasting footage is 1.5 m, and the initial support and temporary support are constructed;

[0164] Please see further Figure 13 A horseshoe-shaped blasting pilot pit 37 with a height of 1.8m, a width of 1.8m and a depth of 1.5m was excavated in the middle and lower part of the lower left pilot pit 34 in the tunnel, and blast holes 38 were arranged along the side walls and top of the blasting pilot pit, with a spacing of 0.4m between adjacent blast holes 38.

[0165] Excavate a boundary line on the lower left pilot pit 34 and drill holes on both sides of the boundary line to lay out two layers of staggered peripheral blast holes 41 and shock-absorbing holes 42;

[0166] Arrange auxiliary blasting holes 43 in the lower left pilot pit 34, which are a combination of straight and arc shapes;

[0167] Using the micro-difference time-delay detonation technology, the left lower pilot pit 34 was blasted as a whole with a blasting depth of 1.5m. The invert arch was mechanically excavated and initial and temporary supports were implemented.

[0168] Please see further Figure 14 , excavate a boundary line on the middle and lower pilot pit 35 and drill holes on the top of the boundary line, laying out a layer of staggered peripheral explosion holes 41 and shock-absorbing holes 42;

[0169] Arrange auxiliary blasting holes 43 in a combination of straight and arc shapes on the middle and upper pilot pit 35;

[0170] Using the micro-difference time-delay detonation technology, the middle and upper pilot pit 35 was blasted as a whole with a blasting depth of 1.5m, and initial support and temporary support were implemented;

[0171] Please see further Figure 14 and Figure 15 , a linear auxiliary blasting hole 43 is arranged in the middle and lower pilot pit 36;

[0172] Using the micro-difference delayed detonation technology, the middle and lower pilot pit 35 was blasted as a whole with a blasting advance of 1.5m. The inverted arch part was mechanically excavated and initial support and temporary support were applied. The temporary support was removed and the large-section excavation was completed.

[0173] Repeat the above steps. After the full-section excavation is completed, the secondary lining is applied simultaneously until the tunnel is through.

[0174] Finally, it should be noted that the embodiments disclosed in the present invention are only preferred embodiments of the present invention, which are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some of the technical features therein can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A construction method for blasting vibration reduction of a tunnel under a existing building, characterized in that The method includes: First, construct a tunnel shock-absorbing advanced support system; then excavate and blast a pilot tunnel, and arrange blast holes; arrange peripheral blast holes and shock-absorbing holes; arrange auxiliary blast holes; and finally conduct overall blasting. The excavation and blasting of the pilot tunnel, arranging blast holes; arranging peripheral blast holes and shock-absorbing holes; arranging auxiliary blast holes; and conducting overall blasting are carried out in sequence in the upper right pilot tunnel, lower right pilot tunnel, upper left pilot tunnel, lower left pilot tunnel, middle upper pilot tunnel, and middle lower pilot tunnel of the tunnel according to the spatial order. The excavation and blasting of the pilot tunnel, arranging blast holes includes: excavating a pilot tunnel in the middle and lower parts of the upper right pilot tunnel, lower right pilot tunnel, upper left pilot tunnel, and lower left pilot tunnel, and the pilot tunnel is a blasting pilot tunnel; drilling holes at the top and sides along the boundary line of the blasting pilot tunnel, and the holes are blast holes for loading explosives for blasting. The arrangement of peripheral blast holes and shock-absorbing holes includes: drilling holes along the dividing line of the upper right pilot tunnel, lower right pilot tunnel, upper left pilot tunnel, lower left pilot tunnel, and upper right pilot tunnel, and selecting some of the drilled holes to load explosives as peripheral blast holes, and the drilled holes without loading explosives as shock-absorbing holes. The drilled holes distributed along the boundary line in the upper right pilot tunnel, lower right pilot tunnel, upper left pilot tunnel, and lower left pilot tunnel are in two layers. Among them, the layer of drilled holes close to the boundary line is the outer layer of drilled holes, and the other layer of drilled holes is the inner layer of drilled holes; the shock-absorbing holes and peripheral blast holes in the outer layer of drilled holes and the inner layer of drilled holes are arranged at intervals and staggered. The peripheral blast holes and shock-absorbing holes arranged on the middle upper pilot tunnel are in one layer and are arranged at intervals in sequence.

2. The blasting vibration reduction construction method for the existing building's underpass tunnel according to claim 1, characterized in that, The peripheral blast holes and shock-absorbing holes arranged in the upper right pilot tunnel and the upper left pilot tunnel are located on both sides and the top of the upper right pilot tunnel and the upper left pilot tunnel. The peripheral blast holes and shock-absorbing holes arranged in the lower right pilot tunnel and the lower left pilot tunnel are located on both sides of the lower right pilot tunnel and the lower left pilot tunnel.

3. A blasting vibration reduction construction method for an existing building's underpass tunnel according to claim 1, characterized in that, Arranging auxiliary blast holes includes: drilling holes in the upper right pilot tunnel, lower right pilot tunnel, upper left pilot tunnel, lower left pilot tunnel, middle upper pilot tunnel, and middle lower pilot tunnel and then loading explosives as auxiliary blast holes.

4. A blasting vibration reduction construction method for an existing building's underpass tunnel according to claim 3, characterized in that, The arrangement method of the auxiliary blast holes is a combination of linear and arc shapes. Among them, the spacing and row spacing between the auxiliary blast holes are greater than those of the surrounding blast holes and greater than the minimum resistance line.

5. A blasting vibration reduction construction method for an existing building's underpass tunnel according to claim 4, characterized in that, In the upper right pilot tunnel and the upper left pilot tunnel, the auxiliary blast holes close to the inner layer of drilled holes are distributed in an arc shape. The auxiliary blast holes located in the middle upper pilot tunnel are distributed in layers. Among them, the auxiliary blast holes in the topmost layer of the middle upper pilot tunnel are arranged in an arc, and the auxiliary blast holes below are arranged in a straight line. The auxiliary blast holes located in the middle lower pilot tunnel are arranged in a straight line.

6. The blasting vibration reduction construction method for an existing building's underpass tunnel according to claim 1, characterized in that, The overall blasting includes using millisecond delay initiation for overall blasting. Among them, the length of the advance of the overall blasting is 1.5 - 1.8 m. After the overall blasting, initial support and temporary support should be constructed.

7. An advanced support system for the blasting vibration reduction construction method of a tunnel under an existing building described in any one of claims 1-6, characterized in that, The advanced support system includes a non-studio advanced steel pipe shed and advanced shock-absorbing small ducts arranged in the soil layer. The studio advanced steel pipe shed includes a first advanced steel pipe, a detachable connection member detachably connected to the first advanced steel pipe, a second advanced steel pipe detachably connected to the detachable connection member, and an auxiliary installation pipe detachably connected to the second advanced steel pipe. Among them, the first advanced steel pipe is a hollow tubular structure with a pointed end and an open end, and its hollow part is the first grouting channel; a first external thread is also provided on the outer periphery of the open end of the first advanced steel pipe; The detachable connection member is a hollow tubular structure, and its hollow part is the second grouting channel. Among them, a stop screw protrusion is provided in the middle of the inner wall of the detachable connection member, and internal threads are provided on both sides of the stop screw protrusion; The second advanced steel pipe is a hollow tubular structure, and its hollow part is the third grouting channel. Among them, a second external thread is provided on the outer periphery of the opening at one end of the second advanced steel pipe, and a plurality of notches are provided at the opening at the other end, and the notches are clamping grooves; Among them, the second external thread, the first external thread and the internal thread are adapted to each other; a plurality of through holes penetrating the pipe wall are also provided on the first advanced steel pipe and the second advanced steel pipe, and among them, the through holes are the first grouting holes; One end of the auxiliary installation pipe is provided with a protrusion, and the protrusion is a clamping part, and among them, the clamping part is adapted to the clamping groove; A protruding pushing connecting piece is provided at the other end of the auxiliary installation pipe; A conical protrusion is provided on the inner wall near the pointed end of the first advanced steel pipe in the first grouting channel, and the conical protrusion is a barb part for fixing the steel reinforcement cage for grouting; The advanced shock-absorbing small pipe is a hollow tubular structure with a pointed end and an open end, and its hollow part is the fourth grouting channel; A plurality of through holes penetrating the pipe wall are provided on the advanced shock-absorbing small pipe, and the through holes on the advanced shock-absorbing small pipe are the second grouting holes.

8. The advanced support system according to claim 7, characterized in that, The lengths of the first advanced steel pipe and the second advanced steel pipe are 5-6 m; The external insertion angles of the first advanced steel pipe and the second advanced steel pipe arranged in the soil layer are 10-15°; When building an advanced steel pipe shed without a working chamber in the soil layer, it is arranged every 6-7 m; The length of the advanced shock-absorbing small pipe is 6-8 m, the external insertion angle penetrating into the soil layer is 5-8°, and it is arranged every 3-4 m; The grouting slurry injected into the advanced shock-absorbing small pipe adopts modified CA mortar; Among them, the modified CA mortar is ordinary CA mortar added with 7.5% mica powder and 10% rubber powder.

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