Tunnel bolting and grouting integrated construction method

Abstract

The invention belongs to the technical field of tunnel construction methods, and particularly relates to a tunnel anchoring and grouting integrated construction method, which comprises the following steps: firstly, excavating a tunnel face, constructing sprayed concrete and local anchor rods of an arch ring part, then, carrying out secondary primary support, and starting to construct grouting anchor pipe support and grouting at a position which lags behind the tunnel face by 50m; the construction method comprises the following steps of: firstly, pouring a bottom plate of the section, constructing a waterproof and drainage system of the arch wall, and pouring a secondary lining of the arch wall and a vault at one time, optimizing complicated procedures, organically combining support anchor rod construction with a radial grouting process, and realizing systematic grouting on an excavated rock surface by utilizing an existing grouting anchor pipe. The expansion shell type radial grouting anchor pipe is adopted for radial grouting water stop construction, the supporting function of the grouting anchor rod is achieved, meanwhile, grouting water stop and surrounding rock reinforcement are carried out on the fractured rock mass, and on the premise that the construction requirement is met, the construction progress is greatly shortened, and damage to tunnel surrounding rock is reduced.

Description

Technical field:

[0001] The invention belongs to the technical field of tunnel construction methods, and specifically relates to a construction method integrating tunnel anchoring and grouting, which avoids damage to surrounding rock and primary support caused by repeated drilling and grouting of anchor rods and radial grouting. Background technology:

[0002] The current undersea tunnel construction process at least includes hanging steel mesh, erecting frames, driving anchor rods, spraying concrete and radial grouting after drilling, charging and blasting to remove slag. It is complicated and time-consuming, slowing down the construction progress. For example, Chinese Patent 202211236765.6 discloses a method for constructing an undersea tunnel, comprising the following steps: S1, splitting grouting, using a first grouting pressure to inject a first grouting liquid into the weathered trough section to be excavated in front of the heading face, so that the first grouting liquid splits the soil of the weathered trough section to be excavated to form slurry vein skeleton cracks, and the radial extension range of the slurry vein skeleton cracks is greater than the radial excavation range of the tunnel; S2, infiltration grouting, using a second grouting pressure to inject a second grouting liquid into the slurry vein skeleton cracks filled with the first grouting liquid, so that the first grouting liquid in the slurry vein skeleton cracks penetrates into the surrounding area of ​​the slurry vein skeleton cracks, and the second grouting liquid fills the slurry vein skeleton cracks, the second grouting pressure is less than the first grouting pressure, the preparation materials of the first grouting liquid and the second grouting liquid both include component A, the preparation materials of the second grouting liquid also include polypropylene crude fiber, and the first grouting liquid and the second grouting liquid can both consolidate to form a consolidated body. Chinese Patent No. 202111165141.5 discloses a method for constructing an undersea tunnel, comprising the following steps: Step 1, prefabricating a tunnel immersed tube in a dry dock; Step 2, installing a floating capsule on the top of the first tunnel immersed tube and sealing the front end of the tunnel; Step 3, setting a second tunnel immersed tube at the end of the first tunnel immersed tube, installing a sealing ring between the two tunnel immersed tubes and fixing them by anchor cables, and then installing a floating capsule on the second tunnel immersed tube; Step 4, repeating Step 3 until a predetermined number of tunnel immersed tubes are connected; Step 5, using a workboat to drag several front sections of the tunnel immersed tube into the water and locate them in the construction area, suspending the tunnel in the water through the floating capsule, and at least one tunnel immersed tube at the rear end is located on land; Step 6, repeating Steps 3-5 until the first tunnel immersed tube moves to the predetermined position on the opposite bank; Step 7, deflate the floating capsules one by one, so that the tunnel immersed tube slowly sinks into the groove of the riverbed; Step 8, anchoring the tunnel inside the tunnel to fix the tunnel immersed tube to the groove; Step 9, finally burying the tunnel immersed tube. At the same time, during the initial support anchor drilling process, many anchor holes will have water leakage, which requires re-hole replacement. At the same time, radial grouting is required to block water in the water holes and the surrounding areas. The special hydrogeological conditions of the offshore drilling and blasting section determine that there is a large area of ​​crack leakage in the tunnel body after excavation, which also requires radial grouting to stop water. A large amount of radial grouting construction has restricted the progress of on-site construction and caused more damage to the existing surrounding rock and initial support.

[0003] Traditional anchors use a pressureless filling grouting method. The slurry can only fill the gap between the anchor and the anchor hole, and cannot penetrate into the cracks in the surrounding rock. After the grouting is completed, there is still a certain amount of leakage, resulting in insufficient density and fullness of the slurry in the hole, and the connection between the slurry and the surrounding rock, and the anchor and the surrounding rock is not dense. For example, Chinese Patent 202410749469.9 discloses an anti-floating anchor rod, comprising a plurality of rod bodies that can be detachably connected in sequence, a grouting channel for inserting a grouting pipe being provided through the rod body, and a plurality of grouting holes connected to the grouting channel being provided through the four sides of the rod body; the bottom end of the rod body connected in the drilled hole is connected to a connecting structure for strengthening the connection with the bearing layer, the rod body connected to the top end of the hole is provided with a supporting structure for supporting and limiting the rod body, the connecting structure comprises a connecting head, the top end of the connecting head can be detachably connected to the rod body through a thread, the connecting head is throughly arranged and connected to the rod body; a movable shaft is provided at one end of the connecting head away from the rod body, one end of the movable shaft passes through the through cavity of the connecting head and can be movably inserted into the hollow cavity of the rod body, a connecting spring is provided at one end of the movable shaft close to the connecting head, one end of the connecting spring is connected to the connecting head, and the other end of the connecting spring is connected to the movable Head, the movable head is movably mounted on the movable shaft; the end of the movable shaft away from the connecting head is connected with a detachable guide drill bit, and the end of the movable head away from the connecting spring is connected with a movable sleeve, and the movable sleeve is movably mounted on the movable shaft; a number of movable limit grooves are opened around the movable shaft, and movable limit sliding blocks are respectively arranged in the movable limit grooves, and the movable limit sliding blocks are slidably adapted to the movable limit grooves, and the movable sleeve is used to limit the movable limit sliding blocks in the movable limit grooves; the movable limit sliding blocks and the bottom ends of the movable limit grooves are respectively provided with first deformation springs, one end of the first deformation spring is connected to the bottom end of the movable limit groove, and the other end of the first deformation spring is connected to the movable limit sliding block, and a number of movable rods are hinged around the end of the movable head away from the connecting head, and a limit block is hinged at one end of the movable rod away from the connecting head, and the limit block is obliquely hinged to the connecting limit plate through the connecting rod, and the connecting limit plate is connected to the end of the movable shaft away from the connecting head. Chinese patent 202410526473.9 discloses a prefabricated anchor with strong pull-out resistance, including a prefabricated pull-out anchor, which consists of an anchor section and a free section. The anchor section is arranged inside the anchor body, and the outer periphery of the free section is provided with threads. A fixing nut is threadedly connected to one side of the free section, and a fastening sleeve is threadedly connected to the side of the fixing nut away from the anchor body. A handwheel is fixedly connected to one side of the fastening sleeve, and an external thread is provided on the side of the anchor section away from the free section. Therefore, it is necessary to develop and design a tunnel anchor-grouting integrated construction method to effectively speed up the construction speed and solve the problems of water discharge and damage in the anchor hole of the submarine tunnel, and the damage caused to the surrounding rock and primary support by repeated drilling and grouting of anchors and radial grouting. Summary of the invention:

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and to develop and design an integrated tunnel anchoring and grouting construction method, which enables the anchor rod drilling holes to also serve as radial grouting holes, taking into account radial grouting and water-stopping construction, thereby improving the tunnel construction efficiency.

[0005] In order to achieve the above-mentioned purpose, the present invention relates to a tunnel anchoring and grouting integrated construction method suitable for serving the tunnel Grade III surrounding rock section, wherein 15 cm thick CF35 shotcrete and anchor rods are constructed separately, and the specific process is as follows:

[0006] (1) Full-section excavation is carried out by smooth blasting, and the full section is excavated in one go, with a feed of 3-4m per cycle;

[0007] (2) First-order initial support: 10 cm thick CF35 shotcrete;

[0008] (3) Find the top after excavation and implement auxiliary reinforcement measures to stabilize the surrounding rock;

[0009] (4) Second-order primary support: grouting anchor pipe support and grouting are started at 50 m behind the tunnel face;

[0010] (5) Re-spraying 5 cm thick CF35 shotcrete;

[0011] (6) Concrete the bottom slab of this section (including the tunnel bottom drainage system);

[0012] (7) Construct the arch wall drainage system and use the lining formwork trolley to pour the secondary lining in one go (the arch wall lining is constructed in one go);

[0013] Continuous monitoring is carried out during the construction process.

[0014] The CF35 shotcrete involved in the present invention is a steel fiber concrete, which uses 1000-1800MPa grade, 35mm long, 0.55mm diameter bonded row steel fibers; wherein,

[0015] The steel fiber is ordinary carbon steel, with a dosage of 30-45kg / m 3 ;

[0016] The dosage of polypropylene structural fiber is 2-6kg / m 3 .

[0017] The reinforcement auxiliary measures involved in the present invention are to carry out 3.0m long local anchor rod construction at risk points such as positions where there is a risk of block falling but it is not suitable to continue clearing the top and relatively protruding rock blocks after tunnel excavation according to the top finding situation. At the same time, steel mesh or grid steel frame is applied for reinforcement to stabilize the surrounding rock in time.

[0018] The local anchor rod of the present invention is a φ25 shell expansion radial grouting anchor pipe, and the grouting anchor pipe is a φ32mm shell expansion radial grouting anchor pipe;

[0019] The main structure of the shell expansion type radial grouting anchor pipe includes an anchor rod body and an expansion anchor head arranged at its end and a connecting grouting ball valve. The expansion anchor head is composed of a main structure including an inner wedge and an expansion sheet arranged thereon. A grout stopper or a grout stopper mold bag, a gasket and a nut are sleeved on the outside of the anchor rod body. A grout overflow hole is also arranged on the inner wedge. The expansion sheet can slide in the wedge groove of the inner wedge.

[0020] The expansion shell anchor head can ensure the engagement between the expansion shell radial grouting anchor pipe and the surrounding rock. The grout stopper or grout stopper mold bag can not only ensure the sealing of the hole during the grouting process, but also ensure the set grout stopper rock plate thickness, effectively increasing the grouting pressure, and achieving grout filling in the hole while continuing to diffuse outward along the surrounding rock cracks;

[0021] After grouting is completed, the grouting ball valve is closed to maintain pressure in the hole and prevent leakage of grout from the hole mouth, which can not only ensure the density and fullness of the grout filling in the hole, but also can grout to block water and reinforce the surrounding rock;

[0022] The expansion shell radial grouting anchor pipe is constructed by drilling rig or manual operation with a spacing of 1.5m×1.5m and plum blossom piles arranged. Cement slurry is injected into the grouting stop mold bag to fill it tightly and form a grouting stop section to ensure a secure anchor.

[0023] The selection criteria of the grouting materials involved in the present invention are as follows:

[0024] When the water output of a single hole is ≤50L / min, use ultra-fine cement single liquid slurry;

[0025] When the water output of a single hole is ≥50L / min, select in the order of ordinary cement slurry → ultra-fine cement single liquid slurry;

[0026] In order to enhance the grouting effect, durable and environmentally friendly chemical slurry is used. The mix ratio of chemical slurry is cement: water = 0.5:1~1:1, and the grouting pressure is 1.5~2.0Mpa.

[0027] The process involved in the present invention is as follows: the principle of starting to apply grouting anchor pipe support at 50m of the lagging heading face is that it is known through surrounding rock deformation monitoring data that the service tunnel III level surrounding rock deformation is completed 3-5d after excavation. With the continuous advancement of the heading face, the service tunnel is in a stable state after the first-sequence primary support is applied. According to the construction progress, the first-sequence primary support section is 50m, and then the second-sequence primary support is applied, and the safety of the tunnel structure is further improved.

[0028] The monitoring contents involved in the present invention include:

[0029] For jointed hard rock, regardless of the surrounding rock grade III, IV, or V, the surrounding rock deformation is limited after the excavation of the service tunnel chamber is completed, and the monitoring data under different surrounding rock grades do not show obvious differences;

[0030] During subsequent construction, attention should be paid to the impact of mainline tunnel face blasting on the service tunnel;

[0031] For the Class III surrounding rock section, there may be a risk of block falling. Focus on the geological forecast and combine the surrounding rock conditions revealed by excavation to fully assess the possible risk of block falling.

[0032] After excavation is completed, the change information of the surrounding rock free blocks (key blocks) is captured in time, and the initial monitoring frequency is 2 times / day.

[0033] Compared with the prior art, the present invention optimizes the complex process, organically combines the construction of support anchor rods with the radial grouting process, and utilizes the existing grouting anchor pipes to realize systematic grouting of the excavated rock surface. The expansion shell-type radial grouting anchor pipes are used to take into account the radial grouting and water-stopping construction, thereby further improving the construction efficiency of the tunnel and giving full play to the function of the anchor rod drilling hole also serving as the radial grouting hole. The principle is scientific and reliable, which not only realizes the support function of the grouting anchor rod, but also performs grouting and water blocking and surrounding rock reinforcement on the fractured rock mass. On the premise of meeting the construction requirements, the construction progress is greatly shortened and the damage to the tunnel surrounding rock is reduced. Description of the drawings:

[0034] Figure 1 This is a schematic diagram of the construction cross section involved in Example 1 of the present invention.

[0035] Figure 2 The present invention is a schematic diagram of the main structural principle of the shell expansion type radial grouting anchor pipe.

[0036] Figure 3 It is a schematic diagram of the main structure of the grouting joint involved in the present invention. Specific implementation method:

[0038] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods.

[0039] Embodiment 1:

[0040] The specific process of a tunnel anchoring and grouting integrated construction method involved in this embodiment is as follows: Figure 1 As shown,

[0041] First, the full-section method is used to excavate the tunnel face ①, and 10 cm thick shotcrete and local anchors are applied to the arch ring ②, and the above steps are repeated.

[0042] Then, the second-order primary support was carried out, and grouting anchor pipe support and grouting were started at 50m behind the lagging face, and 5cm thick shotcrete was applied to the arch wall ③;

[0043] Finally, pour the bottom plate ④ of this section (including the tunnel bottom drainage system), construct the arch wall drainage system, and use the lining formwork trolley to pour the secondary lining of the arch wall ③ and the arch top ⑤ at one time.

[0044] The local anchor rod and grouting anchor pipe involved in this embodiment adopts a shell expansion radial grouting anchor pipe with a wall thickness of 5mm and a length of 3m. Its main structure is as follows: Figure 2 As shown, it comprises an anchor rod body 1, an expansion shell anchor head 2, a grouting ball valve 3, a grouting stopper 4, a pad 5 and a nut 6; the outer shell is a threaded structure, and the front end of the anchor rod body 1 with a hollow structure inside is provided with an expansion shell anchor head 2, and the rear end is provided with a grouting ball valve 3, and the outer sleeve is provided with a grouting stopper 4 and a pad 5, and the grouting stopper 4 and the pad 5 are fastened and limited by a nut 6 provided on the anchor rod body 1;

[0045] The main structure of the shell expansion anchor head 2 includes an inner wedge 21, an expansion piece 22 and a grout overflow hole 23; two expansion pieces 22 with an angle of 180° are slidably arranged in the wedge groove of the inner wedge 21, and an overflow hole 23 is arranged at the end;

[0046] When using, Figure 3 As shown:

[0047] First, the shell expansion radial grouting anchor pipe is connected to the grouting machine by connecting the grouting ball valve 3 and the grouting joint 10 through a threaded connection. One end of the grouting joint 10 with two extended spiral rods 11 is the grouting anchor pipe connection end 12, and the other end is the grouting machine connection end 13. The extended spiral rods 11 are provided to facilitate the installation and removal of the grouting joint and the shell expansion radial grouting anchor pipe.

[0048] Then, remove the binding wire of the shell expansion piece 22, insert the shell expansion radial grouting anchor pipe into the grouting hole, and rotate the anchor body 1 exposed outside the surrounding rock to unfold the two shell expansion pieces 22 and make close contact with the surrounding rock, bite, and generate friction resistance with the anchor hole wall to form a supporting anchoring force. When the anchor body 1 cannot be twisted, it proves that the shell expansion piece 22 is in close contact with the surrounding rock.

[0049] The backing plate 5 is fastened by the nut 6, so that one surface of the backing plate 5 is in close contact with the stop plug 4, the other surface is in close contact with the nut 6, and the side surface is in close contact with the rock surface;

[0050] Finally, grouting is performed, and the slurry passes through the grouting channel: the hollow channel of the anchor body 1 to reach the overflow hole 23;

[0051] The stopper 4 can effectively block the grouting hole during the grouting process to prevent the grout from overflowing from the grouting hole;

[0052] The pad 5 is in close contact with the surrounding rock during grouting and is the last barrier between the grouting hole and the external environment. It has deformation ability and can prevent the anchor body 1 from being damaged by tension.

Claims

1. A tunnel anchoring and grouting integrated construction method, characterized in that: The specific process is as follows: (1) The entire section is excavated in one step, with a feed of 3-4m per cycle; (2) First-order initial support, CF35 shotcrete is applied; (3) Find the top after excavation and implement auxiliary reinforcement measures; (4) Second-order primary support: grouting anchor pipe support and grouting are started at 50 m behind the tunnel face; (5) Re-spraying CF35 shotcrete; (6) Concrete the bottom plate of the section; (7) Construct the arch wall drainage system and pour the secondary lining at one time.

2. The tunnel anchoring and grouting integrated construction method according to claim 1 is characterized in that: Continuous monitoring is carried out during the construction process.

3. The tunnel anchoring and grouting integrated construction method according to claim 2 is characterized in that: CF35 shotcrete is steel fiber concrete, which uses 1000-1800MPa grade, 35mm long, 0.55mm diameter bonded steel fibers in rows; the steel fibers are ordinary carbon steel, with a dosage of 30-45kg / m 3 ; The dosage of polypropylene structural fiber is 2-6kg / m 3 .

4. The tunnel anchoring and grouting integrated construction method according to claim 1, characterized in that: After tunnel excavation, auxiliary reinforcement measures are carried out according to the top-finding situation, 3.0m long local anchor rods are constructed at locations where there is a risk of block falling but it is not suitable to continue clearing the top, as well as at relatively prominent rock risk points. At the same time, steel mesh or grid steel frames are applied for reinforcement.

5. The tunnel anchoring and grouting integrated construction method according to claim 1 is characterized in that: The selection criteria for grouting materials are as follows: When the water output of a single hole is ≤50L / min, use ultra-fine cement single liquid slurry; When the water output of a single hole is ≥50L / min, the order of ordinary cement slurry → ultrafine cement single-liquid slurry should be followed.

6. The tunnel anchoring and grouting integrated construction method according to any one of claims 1 to 5, characterized in that: The local anchor is a φ25 expansion shell type radial grouting anchor pipe, and the grouting anchor pipe is a φ32mm expansion shell type radial grouting anchor pipe; the main structure of the expansion shell type radial grouting anchor pipe includes the anchor body and the expansion shell anchor head arranged at its end and the connecting grouting ball valve, the expansion shell anchor head is composed of the main structure including the inner wedge and the expansion shell piece arranged thereon, the outside of the anchor body 1 is also provided with a grouting stop plug or a grouting stop mold bag, a gasket and a nut, the inner wedge is also provided with a grouting overflow hole, and the expansion shell piece slides in the wedge groove of the inner wedge.

7. The tunnel anchoring and grouting integrated construction method according to claim 5, characterized in that: The chemical slurry with a mix ratio of cement: water = 0.5:1~1:1 is used, and the grouting pressure is 1.5~2.0Mpa.

8. The tunnel anchoring and grouting integrated construction method according to claim 6, characterized in that: When using, First, connect the shell expansion radial grouting anchor pipe to the grouting machine; Then, the binding wire of the shell expansion piece 22 is removed, and the shell expansion radial grouting anchor pipe is inserted into the grouting hole. The two shell expansion pieces 22 are unfolded and in close contact with the surrounding rock by rotating the anchor rod body 1 exposed outside the surrounding rock to engage with each other. The backing plate 5 is fastened by the nut 6, so that one surface of the backing plate 5 is in close contact with the stop plug 4, the other surface is in close contact with the nut 6, and the side surface is in close contact with the rock surface; Finally, grouting.

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