A construction method for preventing cracking and falling of tunnel plain concrete secondary lining

Abstract

The present application relates to a construction method for preventing cracking and falling of the secondary lining of plain concrete in a tunnel, comprising: transporting a prefabricated wire rope mesh to a construction site; connecting one end of the wire rope mesh to the reinforced concrete lining already constructed in the tunnel, and connecting the other end to a waterproof board laying trolley; moving the waterproof board laying trolley to tighten the wire rope mesh; moving the lining formwork trolley to the wire rope mesh laying area and fixing it, and installing a head formwork at the end of the lining formwork trolley; using the concrete pouring window of the lining formwork trolley to continuously pour the lining concrete in layers and symmetrically and vibrate it to make it dense; disassembling the connection point between the waterproof board laying trolley and the wire rope mesh; moving the lining formwork trolley and the waterproof board laying trolley to the next wire rope mesh laying area to carry out the wire rope mesh laying and lining concrete pouring construction. Compared with the steel mesh, the wire rope mesh of the present application has high tensile strength, good integrity, and is easy to construct, and it greatly reduces the use of steel materials, thereby reducing construction costs.

Description

Technical Field

[0001] The present application relates to the technical field of tunnel secondary lining construction, and in particular to a construction method for preventing the cracking and falling of the plain concrete secondary lining of a tunnel. Background Art

[0002] The construction of mining-based traffic tunnels mainly adopts a composite lining structure. When the surrounding rock conditions of the tunnel are good, the surrounding rock has strong self-stabilization ability, and the secondary lining of the tunnel basically does not bear the surrounding rock pressure. Plain concrete secondary lining is usually used as a structural safety reserve and also has functions such as waterproofing, later installation of various equipment and facilities, and aesthetics.

[0003] Since the plain concrete lining is a cast-in-place concrete structure, it is subject to the limitations of the working conditions and construction technology in the tunnel, as well as the changes in the working environment of the tunnel during the operation period. As a result, cracking and falling accidents of the plain concrete lining in the operating tunnel often occur, seriously threatening the safety of tunnel traffic.

[0004] In order to inhibit the development of early cracks on the surface of tunnel lining concrete and prevent sudden block falling disasters in the plain concrete lining of operating tunnels, in recent years, railway tunnels have adopted the method of setting steel mesh in the arch of plain concrete lining.

[0005] This method begins with the erection of a steel grid to secure the steel mesh. The grid consists of multiple thick steel bars, spaced at regular intervals along the tunnel's longitudinal direction. Connecting steel bars are then installed between the grids. Once the grids and connecting bars are stabilized, the steel mesh is laid and connected in the tunnel arch area. The lining trolley is then moved to pour the lining concrete.

[0006] Based on actual on-site construction conditions and combined with the quality inspection results of a large number of constructed steel mesh lining sections, the steel mesh constructed using this method has many quality problems, such as difficulty in positioning, concrete flow during lining pouring, displacement and partial loss of steel mesh due to vibration, and insufficient or excessive thickness of the steel mesh protective layer in the lining concrete after pouring, which seriously affects the effectiveness of the steel mesh in preventing cracking and falling of the concrete lining.

[0007] In addition, the currently commonly used method of laying steel mesh requires the installation of a large number of grid steel frames and connecting steel bars to fix the steel mesh. The grid steel frames use a large proportion of steel and consume a lot of labor, but they only serve to assist in fixing the steel mesh, resulting in a lot of engineering waste. Summary of the Invention

[0008] The embodiment of the present application provides a construction method for preventing cracking and falling of the secondary lining of plain concrete in a tunnel, so as to solve the problem of cracking and falling of the secondary lining of plain concrete in a tunnel in the related art.

[0009] The present application provides a construction method for preventing cracking and falling of a plain concrete secondary lining of a tunnel, comprising:

[0010] Transport the prefabricated wire rope net to the tunnel construction site where the secondary lining is to be constructed, and position the waterproof sheet laying trolley and lining formwork trolley in the tunnel;

[0011] After the wire rope net is unfolded in the tunnel, one end of the wire rope net is connected to the reinforced concrete lining that has been constructed in the tunnel, and the other end is connected to the waterproof board laying trolley;

[0012] Move the waterproof board laying trolley to tighten the wire rope net, tighten the wire rope net from a loose state to a tensioned state, and then fix the waterproof board laying trolley;

[0013] After the wire rope net is tightened, check whether the connection nodes of the wire rope net are firm and re-measure the laying position of the wire rope net in the tunnel;

[0014] Move the lining formwork trolley to the wire rope net laying area and fix it, and install the head formwork at the end of the lining formwork trolley;

[0015] Use the concrete pouring window of the lining formwork trolley to continuously pour the lining concrete in layers symmetrically and vibrate to compact it;

[0016] After the lining concrete reaches the set strength, remove the head formwork and dismantle the connection points between the waterproof board laying trolley and the wire rope net;

[0017] Move the lining formwork trolley and waterproof board laying trolley to the next wire rope net laying area to carry out wire rope net laying and lining concrete pouring construction.

[0018] In some embodiments: the wire rope net includes a plurality of longitudinal steel ropes extending along the length direction of the tunnel, and a plurality of circumferential steel ropes formed along the cross-sectional contour line of the tunnel, and the plurality of longitudinal steel ropes and the plurality of circumferential steel ropes are fixedly connected to each other at the nodes where the plurality of longitudinal steel ropes and the plurality of circumferential steel ropes intersect.

[0019] In some embodiments: multiple longitudinal steel wire ropes and multiple circumferential steel wire ropes together form a rectangular mesh or a diamond mesh, the distance between two adjacent longitudinal steel wire ropes and two adjacent circumferential steel wire ropes is 100-200 mm, the diameters of the longitudinal steel wire ropes and the circumferential steel wire ropes are 2-4 mm, and the nodes where the multiple longitudinal steel wire ropes and the multiple circumferential steel wire ropes intersect are connected by binding or wire rope buckles.

[0020] In some embodiments: the length of a single piece of the wire rope net is greater than or equal to the length of the lining formwork trolley. If the width of the wire rope net is less than the length of the cross-sectional contour line of the tunnel, two or more wire rope nets are laid in parallel in a circumferential direction in the tunnel, and the overlapping parts of the two adjacent wire rope nets are fixedly connected.

[0021] In some embodiments: internal steel bars connecting the longitudinal steel wire ropes of the steel wire rope net are pre-embedded in the reinforced concrete lining. When the position or number of the pre-embedded internal steel bars does not match the longitudinal steel wire ropes, longitudinal steel bars connecting one end of the longitudinal steel wire ropes are implanted in the reinforced concrete lining, or holes are drilled in the reinforced concrete lining to anchor one end of the longitudinal steel wire rope in the drilled hole in the reinforced concrete lining.

[0022] In some embodiments: a plurality of wire rope anchoring clamps connecting the longitudinal steel ropes of the wire rope net are provided on the curved guide rail at the rear of the waterproof board laying trolley, and the connecting line of the plurality of wire rope anchoring clamps on the curved guide rail is adapted to the cross-sectional contour line of the tunnel and the distance from the outer wall of the lining formwork trolley is 30-100 mm.

[0023] In some embodiments: a plurality of longitudinal wire rope avoidance grooves are opened on the head template, the longitudinal wire rope avoidance grooves are used to insert the longitudinal wire rope, the head template is a fan-shaped plate structure, and the notches of the plurality of longitudinal wire rope avoidance grooves face the outer arc surface of the head template.

[0024] In some embodiments: the length of the single-piece steel wire rope net is greater than or equal to the length of the lining formwork trolley, and the ratio of the length of the single-piece steel wire rope net to the length of the lining formwork trolley is n, and n≥1;

[0025] Divide the single wire rope net into n wire rope net sections along the length direction of the single wire rope net;

[0026] When n≥2, the head formwork is removed after the lining concrete of the n-1th wire rope net section reaches the set strength, and the lining formwork trolley is moved to the nth wire rope net section before pouring the lining concrete.

[0027] In some embodiments: after all the steel wire rope net sections of the single steel wire rope net are poured with lining concrete, the head formwork and the connection points between the waterproof sheet laying trolley and the steel wire rope net are removed;

[0028] Move the lining formwork trolley and waterproof sheet laying trolley to the next wire rope net laying area to lay the next piece of wire rope net;

[0029] When laying the next piece of wire rope net in the tunnel, connect one end of the next piece of wire rope net to the end of the previous piece of wire rope net;

[0030] After connecting the other end of the next piece of wire rope net to the waterproof board laying trolley, move the waterproof board laying trolley to tighten the next piece of wire rope net.

[0031] In some embodiments, two interconnected steel wire rope nets are connected by any one or more of a pressing method, a tying method, and a clamping method.

[0032] The beneficial effects of the technical solution provided by this application include:

[0033] The embodiment of the present application provides a construction method for preventing cracking and falling of the secondary lining of plain concrete in a tunnel. According to the construction method for preventing cracking and falling of the secondary lining of plain concrete in a tunnel, a prefabricated wire rope net is transported to the tunnel construction site where the secondary lining is to be constructed, and a waterproof board laying trolley and a lining template trolley are put in place in the tunnel; after the wire rope net is unfolded in the tunnel, one end of the wire rope net is connected to the reinforced concrete lining constructed in the tunnel, and the other end is connected to the waterproof board laying trolley; the waterproof board laying trolley is moved to tighten the wire rope net, and after the wire rope net is tightened from a relaxed state to a tensioned state, the waterproof board laying trolley is fixed;

[0034] After the wire rope net is tensioned, check whether the connection nodes of the wire rope net are firm, and re-measure the laying position of the wire rope net in the tunnel; move the lining formwork trolley to the wire rope net laying area and fix it, and install the head formwork at the end of the lining formwork trolley; use the concrete pouring window of the lining formwork trolley to continuously pour the lining concrete in layers symmetrically and vibrate it to make it dense; after the lining concrete reaches the set strength, remove the head formwork, dismantle the connection point between the waterproof board laying trolley and the wire rope net; move the lining formwork trolley and the waterproof board laying trolley to the next wire rope net laying area to carry out wire rope net laying and lining concrete pouring construction.

[0035] Therefore, the construction method of the present application for preventing cracking and falling of the plain concrete secondary lining of the tunnel fully utilizes the advantages of the steel wire rope, such as high strength, good softness, suitability for traction and pulling, light weight, and ease of transportation and installation and construction. Since the steel wire rope net has a soft structure, the front and rear ends are fixed to the constructed lining and waterproof board laying trolley and the linear shape is straight after being tightened, which can achieve precise positioning and greatly improve the construction quality. Since the tensile strength of the steel wire rope is several times that of ordinary steel bars, and its weight is light and it can be transported in rolls, it is possible to realize factory-made large-scale steel wire rope nets, which can lay and hang multiple lining trolley lengths at a time, reduce the workload of on-site laying, and facilitate operation. Compared with the steel mesh, the steel wire rope net has high tensile strength, good integrity, simple construction, and greatly reduces the use of steel materials, thereby reducing construction costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0037] Figure 1 A flow chart of a method according to an embodiment of the present application;

[0038] Figure 2 A schematic cross-sectional view of a tunnel secondary lining according to an embodiment of the present application;

[0039] Figure 3 This is a schematic structural diagram of the tunnel secondary lining and wire rope net according to an embodiment of the present application;

[0040] Figure 4 This is a schematic structural diagram of a wire rope net according to an embodiment of the present application;

[0041] Figure 5 This is a structural schematic diagram of the connection between the reinforced concrete lining and waterproof board laying trolley and the wire rope net in an embodiment of the present application.

[0042] Reference numerals:

[0043] 1. Secondary lining; 2. Wire rope mesh; 2.1. Longitudinal wire rope; 2.2. Circumferential wire rope; 2.3. Wire rope buckle; 3. Reinforced concrete lining; 4. Internal reinforcement; 5. Waterproof board laying trolley; 6. Longitudinal reinforcement; 7. Wire rope anchoring clamp; 8. Rope clamp. DETAILED DESCRIPTION

[0044] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0045] The embodiment of the present application provides a construction method for preventing cracking and falling of the secondary lining of plain concrete in a tunnel, which can solve the problem of cracking and falling of the secondary lining of plain concrete in a tunnel in the related art.

[0046] See also Figures 1 to 5 As shown, the embodiment of the present application provides a construction method for preventing cracking and falling of a plain concrete secondary lining of a tunnel, comprising:

[0047] Step 101: Transport the prefabricated wire rope net 2 to the tunnel construction site where the secondary lining 1 is to be constructed, and position the waterproof sheeting trolley 5 and the lining formwork trolley within the tunnel. In this step, the wire rope net 2 is prefabricated in the factory and transported to the tunnel construction site. The wire rope net 2 consists of longitudinal wire ropes 2.1 and circumferential wire ropes 2.2, which are securely connected at their intersections.

[0048] The mesh shape of the wire rope net 2 can be various regular polygonal shapes such as rectangle (such as square), rhombus, etc. The longitudinal length of each wire rope net 2 is generally not less than the length of a template trolley and considering a certain margin, the laying length range can also be lengthened once as needed.

[0049] The width of the wire rope net 2 should be increased as much as possible while meeting on-site construction conditions and transportation conditions to reduce the number of circumferential connection points between each wire rope net 2. The width of a single wire rope net 2 is preferably 4-8m.

[0050] Step 102 , after the steel wire rope net 2 is unfolded in the tunnel, one end of the steel wire rope net 2 is connected to the reinforced concrete lining 3 constructed in the tunnel, and the other end is connected to the waterproof board laying trolley 5 .

[0051] In this step, the internal steel bars 4 arranged in the reinforced concrete lining 3 constructed in the tunnel are used as fixing points, and the longitudinal steel wire ropes 2.1 of the wire rope net 2 are connected and fixed to the internal steel bars 4.

[0052] The existing waterproof board laying trolley 5 in the tunnel is used as the connecting support structure for the other end of the longitudinal steel wire rope 2.1 connected to the steel wire rope net 2. The waterproof board laying trolley 5 and lining template trolley required for tunnel construction are used, and there is no need to add additional construction platforms and other equipment.

[0053] The curved guide rail at the tail of the waterproof board laying trolley 5 in front of the wire rope net section to be constructed is used as a connecting support structure for temporarily fixing the wire rope net 2. The curvature, radius, etc. of the guide rail should match the designed position of the pre-laid wire rope net 2. The longitudinal wire rope 2.1 is connected to the waterproof board laying trolley 5 through reserved holes or clips.

[0054] Step 103: Move the waterproof board laying trolley 5 to tighten the wire rope net 2, tighten the wire rope net 2 from a relaxed state to a tensioned state, and then fix the waterproof board laying trolley 5; the wire rope net 2 is in a relaxed state after being connected to the reinforced concrete lining 3 and the waterproof board laying trolley 5. In order to make the shape of the wire rope net 2 match the contour line of the tunnel cross section, the wire rope net 2 needs to be tensioned.

[0055] This step uses mechanical traction to move the waterproof board laying and hanging trolley 5. Steel rails and rollers should be set under the waterproof board laying and hanging trolley 5 to facilitate the movement and fixation of the waterproof board laying and hanging trolley 5. After pulling the waterproof board laying and hanging trolley 5 to tighten the wire rope net 2 into place, the waterproof board laying and hanging trolley 5 is fixed.

[0056] Step 104: After the wire rope net 2 is tightened, check whether the connection nodes of the wire rope net 2 are firm, and re-measure the laying position of the wire rope net 2 in the tunnel. If any connection nodes of the wire rope net 2 are loose or changed in position, repair and correct them.

[0057] After the wire rope net 2 is tightened, it is inevitable that some connection parts will become loose and the position will change. In this step, after the wire rope net 2 is tightened, the connection between the nodes of the wire rope net 2, the connection between the meshes, and the front and rear end connections are checked to see whether they are firm, and the positioning of the wire rope net is re-measured to ensure that the positioning accuracy meets the requirements.

[0058] Step 105: Move the lining formwork trolley to the area where the wire rope net 2 is laid and fix it, install the head formwork at the end of the lining formwork trolley, and the head formwork is installed at both ends of the lining formwork trolley. The head formwork then forms a closed space for pouring lining concrete between the lining formwork trolley and the inner wall of the tunnel.

[0059] Step 106: Use the concrete pouring window of the lining formwork trolley to continuously pour the lining concrete in layers symmetrically and compactly. When vibrating the lining concrete, avoid direct contact between the vibrating equipment and the wire rope net 2. The entire process of pouring the lining concrete should be strictly monitored to avoid displacement of the wire rope net 2, loosening and failure of the connection points, etc.

[0060] Step 107: After the lining concrete reaches the set strength to form the secondary lining 1, remove the head formwork, dismantle the connection point between the waterproof board laying trolley and the wire rope net 2, and inspect the construction quality of the secondary lining 1 and the wire rope net 2 after removing the formwork.

[0061] Step 108: After passing the inspection, move the lining formwork trolley and the waterproof board laying trolley 5 to the next wire rope net laying area to lay the wire rope net 2 and pour the lining concrete until the secondary lining 1 of the tunnel is completed.

[0062] The construction method for preventing cracking and falling of the secondary lining of plain concrete in the tunnel according to the embodiment of the present application fully utilizes the advantages of the wire rope net 2, such as high strength, good flexibility, suitability for traction and pulling, light weight, and ease of transportation and installation.

[0063] Since the steel wire rope net 2 has a soft structure, the front and rear ends are fixed to the reinforced concrete lining 3 and the waterproof board laying trolley 5 and the line is straight after being tightened, which can achieve accurate positioning and greatly improve the construction quality.

[0064] Since the tensile strength of steel wire rope is several times that of ordinary steel bars and it is light in weight and can be transported in rolls, large-scale steel wire rope mesh 2 can be manufactured in factories. Multiple lining trolley lengths can be laid at one time, reducing the workload of on-site laying and facilitating operation.

[0065] Compared to steel mesh, wire rope mesh offers higher tensile strength, better integrity, and easier construction. It also significantly reduces steel usage, lowering construction costs. Compared to the commonly used steel mesh and grid steel frame combination, this method can significantly save steel, significantly reducing project investment.

[0066] The 140° setting of the arch of the double-track high-speed railway tunnel is commonly used in China. Taking the steel mesh solution as an example, the grid steel frame + steel mesh solution requires 244.3 kg of steel bars per meter of tunnel (of which 179 kg is used for the grid steel frame to fix the steel mesh).

[0067] The steel wire rope net 2 proposed by this method is used to replace the grid steel frame + steel mesh solution, and only The steel wire rope weighs 13.2kg, and the steel consumption is only 5-6% of the current commonly used solutions. Even considering the price difference between steel wire rope and ordinary steel bar materials, this method can still save more than 80% of the project investment.

[0068] In some alternative embodiments: See Figures 2 to 5 As shown, an embodiment of the present application provides a construction method for preventing cracking and falling of the secondary lining of plain concrete in a tunnel. The wire rope net 2 of the construction method includes a plurality of longitudinal steel wire ropes 2.1 extending along the length direction of the tunnel, and a plurality of annular steel wire ropes 2.2 formed along the cross-sectional contour line of the tunnel. The plurality of longitudinal steel wire ropes 2.1 and the plurality of annular steel wire ropes 2.2 are fixedly connected to each other at the nodes where the longitudinal steel wire ropes 2.1 and the plurality of annular steel wire ropes 2.2 intersect.

[0069] The plurality of longitudinal steel wires 2.1 and the plurality of circumferential steel wires 2.2 together form a rectangular or diamond-shaped mesh. The distance between two adjacent longitudinal steel wires 2.1 and two adjacent circumferential steel wires 2.2 is 100-200 mm, preferably 150 mm. The diameters of the longitudinal steel wires 2.1 and circumferential steel wires 2.2 are 2-4 mm, preferably 4 mm. The nodes where the plurality of longitudinal steel wires 2.1 and circumferential steel wires 2.2 intersect are connected by lashing or by means of wire rope buckles 2.3.

[0070] In some alternative embodiments: See Figures 2 to 5 As shown, an embodiment of the present application provides a construction method for preventing cracking and falling of the secondary lining of plain concrete in a tunnel. In this construction method, the length of a single piece of wire rope net 2 is greater than or equal to the length of the lining formwork trolley. If the width of the wire rope net 2 is less than the length of the cross-sectional contour line of the tunnel, two or more wire rope nets 2 are laid in parallel in a circumferential direction in the tunnel, and the overlapping parts of the two adjacent wire rope nets 2 are fixedly connected by rope clamps 8.

[0071] The longitudinal length of each piece of wire rope mesh 2 in the embodiment of the present application is generally not less than the length of a lining formwork trolley, and a certain margin is allowed. The length range of a single laying can also be extended as needed. Based on the on-site construction organization, multiple lining lengths can be laid at a time. The width of the wire rope mesh 2 should be as wide as possible to reduce the number of circumferential connection points between each piece of wire rope mesh 2 while meeting on-site construction and transportation conditions. The width of the wire rope mesh 2 is preferably 4 to 8 meters.

[0072] When the width of a piece of wire rope net 2 cannot meet the on-site construction conditions and transportation conditions, multiple pieces of wire rope nets 2 need to be connected in a circular manner to form a wire rope net 2 with a wider width. The multiple pieces of wire rope nets 2 are fixedly connected to each other through circular steel wire ropes 2.2, and the connection method is any one or more of the pressing method, binding method, and clamping method.

[0073] Among them, the pressing method is to put the ends of adjacent circumferential steel wire ropes 2.2 into an oblong aluminum alloy casing and press it tightly with a press; the binding method is to overlap the adjacent circumferential steel wire ropes 2.2 to be connected for a certain length, and then use thin iron wire to wrap and fix the overlapping area; the clamping method is to bend one or both ends of the circumferential steel wire rope 2.2 into a ring, and then use a rope clamp 8 to tighten the rope end with the ring.

[0074] In some alternative embodiments: See Figures 2 to 5 As shown, an embodiment of the present application provides a construction method for preventing cracking and falling of the secondary lining of plain concrete in a tunnel. In this construction method, built-in steel bars 4 connecting the longitudinal steel wires 2.1 of the wire rope net 2 are pre-embedded in the reinforced concrete lining 3, and part of the built-in steel bars 4 is exposed outside the reinforced concrete lining 3 to connect the longitudinal steel wires 2.1.

[0075] When the position or number of the pre-buried internal steel bars 4 does not match the longitudinal steel wire rope 2.1, a longitudinal steel bar 6 connected to one end of the longitudinal steel wire rope is implanted in the reinforced concrete lining 3, or a hole is drilled in the reinforced concrete lining 3 to anchor one end of the longitudinal steel wire rope 2.1 in the drilled hole in the reinforced concrete lining 3, thereby also anchoring one end of the longitudinal steel wire rope 2.1 to the reinforced concrete lining 3.

[0076] In some alternative embodiments: See Figures 2 to 5 As shown, an embodiment of the present application provides a construction method for preventing cracking and falling of the secondary lining of plain concrete in a tunnel. In this construction method, a plurality of steel wire rope anchoring clamps 7 for connecting the longitudinal steel wire ropes 2.1 of the steel wire rope net are provided on the arc-shaped guide rail at the tail of the waterproof board laying trolley 5.

[0077] The curved guide rail at the rear of the waterproof board laying trolley 5 serves as a connecting support structure for temporarily fixing the longitudinal steel ropes 2.1 of the wire rope net 2. The curvature, radius, etc. of the guide rail should match the design position of the pre-laid wire rope net 2. The longitudinal steel ropes 2.1 are connected to the waterproof board laying trolley 5 through reserved holes or wire rope anchoring clamps 7.

[0078] The connecting line of multiple wire rope anchoring clamps 7 on the arc guide rail is adapted to the cross-sectional contour line of the tunnel, and the distance between the connecting line of multiple wire rope anchoring clamps 7 on the arc guide rail and the outer wall of the lining formwork trolley is 30-100 mm, preferably 50 mm, to avoid the wire rope net 2 being too close to the outer wall of the lining formwork trolley and exposing the reinforcement.

[0079] In some alternative embodiments: See Figures 2 to 5 As shown, an embodiment of the present application provides a construction method for preventing cracking and falling of the secondary lining of plain concrete in a tunnel. A plurality of longitudinal steel wire rope avoidance grooves are provided on the head template of the construction method. The longitudinal steel wire rope avoidance grooves are used to insert the longitudinal steel wire rope 2.1. The head template is a fan-shaped plate structure, and the notches of the plurality of longitudinal steel wire rope avoidance grooves face the outer arc surface of the head template.

[0080] The header template is provided with multiple longitudinal wire rope avoidance grooves. These grooves are used to prevent interference between the header template and the longitudinal wire ropes when the header template blocks the end of the waterproofing sheet laying trolley 5, which could affect the installation and fixation of the header template. When the longitudinal wire rope 2.1 is placed in the longitudinal wire rope avoidance grooves, the positioning accuracy of the longitudinal wire rope 2.1 is maintained.

[0081] In some alternative embodiments: See Figures 2 to 5 As shown, an embodiment of the present application provides a construction method for preventing cracking and falling of the secondary lining of plain concrete in a tunnel. In this construction method, the length of a single-piece steel wire rope net 2 is greater than or equal to the length of the lining formwork trolley, and the ratio of the length of the single-piece steel wire rope net 2 to the length of the lining formwork trolley is n, and n≥1.

[0082] Along the length direction of the single-piece steel wire rope net 2, the single-piece steel wire rope net 2 is divided into n steel wire rope net sections; when n≥2, after the lining concrete of the n-1th steel wire rope net section reaches the set strength, the head template is removed, and the lining template trolley is moved to the nth steel wire rope net section and the lining concrete is poured. After the length of the single-piece steel wire rope net 2 is lengthened, the number of times the two ends of the single-piece steel wire rope net 2 are fixed can be reduced.

[0083] After the wire rope net sections of the single wire rope net 2 are poured with lining concrete, remove the head template and the connection point between the waterproof board laying trolley 5 and the wire rope net 2; move the lining template trolley and the waterproof board laying trolley 5 to the next wire rope net laying area to lay the next wire rope net 2.

[0084] When laying the next steel rope net 2 in the tunnel, one end of the longitudinal steel rope 2.1 of the next steel rope net 2 is connected end to end with the longitudinal steel rope 2.1 of the previous steel rope net 2. After the other end of the longitudinal steel rope 2.1 of the next steel rope net 2 is connected to the waterproof board laying trolley 5, the waterproof board laying trolley 5 is moved to tighten the next steel rope net 2.

[0085] The longitudinal steel wire ropes 2.1 between the two interconnected steel wire rope nets 2 are connected by any one or more of the following methods: compression, tying, or clamping. The compression method involves inserting the ends of adjacent circumferential steel wire ropes 2.2 into an oblong aluminum alloy sleeve and compacting them with a press. The tying method involves overlapping adjacent circumferential steel wire ropes 2.2 for a certain length and then wrapping a thin wire around the overlapped area to secure it. The clamping method involves bending one or both ends of the circumferential steel wire ropes 2.2 into a loop and then securing the looped rope end with a rope clamp 8.

[0086] How it works

[0087] The embodiment of the present application provides a construction method for preventing cracking and falling of the secondary lining of plain concrete in a tunnel. According to the construction method for preventing cracking and falling of the secondary lining of plain concrete in a tunnel, a prefabricated steel wire rope net 2 is transported to the tunnel construction site where the secondary lining 1 is to be constructed, and a waterproof board laying trolley 5 and a lining template trolley are put in place in the tunnel; after the steel wire rope net 2 is unfolded in the tunnel, one end of the steel wire rope net 2 is connected to the reinforced concrete lining 3 constructed in the tunnel, and the other end is connected to the waterproof board laying trolley 5; the waterproof board laying trolley 5 is moved to tighten the steel wire rope net 2, and after the steel wire rope net 2 is tightened from a relaxed state to a tensioned state, the waterproof board laying trolley 5 is fixed;

[0088] After the wire rope net 2 is tensioned in place, check whether the connection nodes of the wire rope net 2 are firm, and re-measure the laying position of the wire rope net 2 in the tunnel; move the lining formwork trolley to the wire rope net 2 laying area and fix it, and install the head formwork at the end of the lining formwork trolley; use the concrete pouring window of the lining formwork trolley to continuously pour the lining concrete in layers symmetrically and vibrate it to make it dense; after the lining concrete reaches the set strength, remove the head formwork, dismantle the connection point between the waterproof board laying trolley 5 and the wire rope net 2; move the lining formwork trolley and the waterproof board laying trolley 5 to the next wire rope net 2 laying area to lay the wire rope net 2 and pour the lining concrete.

[0089] Therefore, the construction method of the present application for preventing cracking and falling of the plain concrete secondary lining of the tunnel fully utilizes the advantages of the steel wire rope, such as high strength, good softness, suitability for traction and pulling, light weight, and ease of transportation and installation and construction. Since the steel wire rope net 2 has a soft structure, the front and rear ends are fixed to the constructed reinforced concrete lining 3 and the waterproof board laying trolley 5, and the linear shape is straight after being tightened, which can achieve precise positioning and greatly improve the construction quality. Since the tensile strength of the steel wire rope is several times that of ordinary steel bars, and its weight is light and it can be transported in rolls, it is possible to realize factory production of large-scale steel wire rope nets 2, and multiple lining trolley lengths can be laid at a time, reducing the on-site laying workload and making the operation convenient. Compared with the steel mesh, the steel wire rope net 2 has high tensile strength, good integrity, simple construction, and greatly reduces the use of steel materials, thereby reducing construction costs.

[0090] In the description of this application, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0091] It should be noted that, in this application, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0092] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A construction method for preventing cracking and falling of the secondary lining of plain concrete in a tunnel, characterized in that: include: The prefabricated steel wire rope net (2) is transported to the tunnel construction site where the secondary lining (1) is to be constructed, and the waterproof board laying trolley (5) and the lining template trolley are put into place in the tunnel; After the wire rope net (2) is unfolded in the tunnel, one end of the wire rope net (2) is connected to the reinforced concrete lining (3) that has been constructed in the tunnel, and the other end is connected to the waterproof board laying trolley (5); The waterproof board laying trolley (5) is moved to tighten the wire rope net (2), and the wire rope net (2) is tightened from a loose state to a tensioned state, and then the waterproof board laying trolley (5) is fixed; After the wire rope net (2) is tensioned in place, check whether each connection node of the wire rope net (2) is firm, and re-measure the laying position of the wire rope net (2) in the tunnel; Move the lining formwork trolley to the area where the wire rope net (2) is laid and fix it, and install the head formwork at the end of the lining formwork trolley; Use the concrete pouring window of the lining formwork trolley to continuously pour the lining concrete in layers symmetrically and vibrate to compact it; After the lining concrete reaches the set strength, the head template is removed, and the connection point between the waterproof board laying trolley (5) and the wire rope net (2) is disassembled; The lining template trolley and the waterproof board laying trolley (5) are moved to the next wire rope net (2) laying area to carry out the wire rope net (2) laying and lining concrete pouring construction.

2. A construction method for preventing cracking and falling of a plain concrete secondary lining of a tunnel according to claim 1, characterized in that: The wire rope net (2) comprises a plurality of longitudinal wire ropes (2.1) extending along the length direction of the tunnel, and a plurality of circumferential wire ropes (2.2) formed along the cross-sectional contour line of the tunnel, wherein the plurality of longitudinal wire ropes (2.1) and the plurality of circumferential wire ropes (2.2) are fixedly connected to each other at nodes where the plurality of longitudinal wire ropes (2.1) and the plurality of circumferential wire ropes (2.2) intersect.

3. A construction method for preventing cracking and falling of a plain concrete secondary lining of a tunnel as claimed in claim 2, characterized in that: The plurality of longitudinal steel wire ropes (2.1) and the plurality of circumferential steel wire ropes (2.2) together form a rectangular mesh or a diamond mesh, and the distance between two adjacent longitudinal steel wire ropes (2.1) and two adjacent circumferential steel wire ropes (2.2) is 100-200 mm; The diameters of the longitudinal steel wire rope (2.1) and the circumferential steel wire rope (2.2) are 2-4 mm, and the nodes where the plurality of longitudinal steel wire ropes (2.1) and the plurality of circumferential steel wire ropes (2.2) intersect are connected by lashing or steel wire rope buckles (2.3).

4. A construction method for preventing cracking and falling of a plain concrete secondary lining of a tunnel according to any one of claims 1 to 3, characterized in that: The length of a single piece of the steel wire rope net (2) is greater than or equal to the length of the lining template trolley. If the width of the steel wire rope net (2) is less than the length of the cross-sectional contour line of the tunnel, two or more steel wire rope nets (2) are laid in parallel in a circular direction in the tunnel, and the overlapping parts of the two adjacent steel wire rope nets (2) are fixedly connected.

5. A construction method for preventing cracking and falling of a plain concrete secondary lining of a tunnel according to claim 2 or 3, characterized in that: The reinforced concrete lining (3) is pre-buried with internal steel bars (4) connected to the longitudinal steel wire ropes (2.1) of the steel wire rope net (2); When the position or number of the pre-buried internal steel bars (4) does not match the longitudinal steel wire rope (2.1), a longitudinal steel bar (6) connected to one end of the longitudinal steel wire rope (2.1) is embedded in the reinforced concrete lining (3); or a hole is drilled in the reinforced concrete lining (3) to anchor one end of the longitudinal steel wire rope (2.1) in the drilled hole of the reinforced concrete lining (3).

6. A construction method for preventing cracking and falling of a plain concrete secondary lining of a tunnel according to claim 2 or 3, characterized in that: A plurality of steel wire rope anchoring clamps (7) connected to the longitudinal steel wire ropes (2.1) of the steel wire rope net (2) are provided on the curved guide rail at the rear of the waterproof board laying trolley (5). The connecting line of the plurality of steel wire rope anchoring clamps (7) on the curved guide rail is adapted to the cross-sectional contour line of the tunnel and the distance from the outer wall surface of the lining template trolley is 30-100 mm.

7. A construction method for preventing cracking and falling of a plain concrete secondary lining of a tunnel according to claim 2 or 3, characterized in that: The head template is provided with a plurality of longitudinal steel wire rope avoidance grooves, the longitudinal steel wire rope avoidance grooves being used to pass the longitudinal steel wire rope (2.1), the head template is a fan-shaped plate structure, and the notches of the plurality of longitudinal steel wire rope avoidance grooves face the outer arc surface of the head template.

8. A construction method for preventing cracking and falling of a plain concrete secondary lining of a tunnel as claimed in claim 1, characterized in that: The length of the single-piece steel wire rope net (2) is greater than or equal to the length of the lining template trolley, and the ratio of the length of the single-piece steel wire rope net (2) to the length of the lining template trolley is ≥1; Dividing the single-piece steel wire rope net (2) into n steel wire rope net sections along the length direction of the single-piece steel wire rope net (2); When n≥2, the head formwork is removed after the lining concrete of the n-1th wire rope net section reaches the set strength, and the lining formwork trolley is moved to the nth wire rope net section before pouring the lining concrete.

9. A construction method for preventing cracking and falling of a plain concrete secondary lining of a tunnel as claimed in claim 8, characterized in that: After all the steel wire rope net sections of the single steel wire rope net (2) are poured with lining concrete, the head template and the connection points between the waterproof board laying trolley (5) and the steel wire rope net (2) are disassembled; Moving the lining template trolley and the waterproof board laying trolley (5) to the next wire rope net laying area to lay the next piece of wire rope net (2); When laying the next piece of steel wire rope net (2) in the tunnel, one end of the next piece of steel wire rope net (2) is connected end to end with the previous piece of steel wire rope net (2); After the other end of the next piece of steel wire rope net (2) is connected to the waterproof board laying and hanging trolley (5), the waterproof board laying and hanging trolley (5) is moved to tighten the next piece of steel wire rope net (2).

10. A construction method for preventing cracking and falling of a plain concrete secondary lining of a tunnel as claimed in claim 9, characterized in that: The two interconnected steel wire rope nets (2) are connected by any one or more of a pressing method, a tying method, and a clamping method.

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