Construction method for preventing tunnel plain concrete secondary lining from cracking and chipping

Abstract

The invention relates to a construction method for preventing cracking and chipping of a plain concrete secondary lining of a tunnel. The construction method comprises the steps that a prefabricated steel wire rope net is transported to a construction site; one end of a steel wire rope net is connected with a constructed reinforced concrete lining in the tunnel, and the other end of the steel wire rope net is connected with a waterproof plate laying and hanging trolley; the waterproof plate laying and hanging trolley is moved to tension the steel wire rope net; the lining formwork trolley is moved to the steel wire rope net laying area and fixed, and a sealing head formwork is installed at the end of the lining formwork trolley; lining concrete is symmetrically and continuously poured in a layered mode through a concrete pouring window of the lining formwork trolley and vibrated compactly; the connecting point of the waterproof plate laying and hanging trolley and the steel wire rope net is detached; and the lining formwork trolley and the waterproof plate laying and hanging trolley are moved to the next steel wire rope net laying area for steel wire rope net laying and lining concrete pouring construction. Compared with a reinforcing mesh, the steel wire rope mesh is high in tensile strength, good in integrity and easy and convenient to construct, steel materials are greatly reduced, and the construction cost is reduced.

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 secondary lining of a tunnel from cracking and falling off. Background Art

[0002] The construction of mining-method traffic tunnels mainly adopts 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. Usually, plain concrete secondary lining is used as a structural safety reserve and has the functions of 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 limited by the working conditions and construction technology in the tunnel. In addition, due to changes in the working environment of the tunnel during the operation period, 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 of plain concrete lining in 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 first sets up a grid steel frame to fix the steel mesh. The grid steel frame is composed of multiple thick steel bars and is set at regular intervals along the longitudinal direction of the tunnel. Connecting steel bars are set between the grid steel frames. After the grid steel frames and connecting steel bars are stably erected, steel mesh is laid and connected in the arch area of ​​the tunnel, and then the lining trolley is moved to pour the lining concrete.

[0006] According to the actual construction conditions on site and the quality inspection results of a large number of constructed steel mesh lining sections, the steel mesh constructed by 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, insufficient thickness (exposed steel bars) or excessive thickness of the steel mesh protective layer in the lining concrete after pouring, which seriously affects the effect of the steel mesh in preventing the concrete lining from cracking and falling off.

[0007] In addition, the currently commonly used method of laying steel mesh requires the installation of a large number of grating steel frames and connecting steel bars for fixing the steel mesh. The grating steel frames use a large proportion of steel and consume a lot of labor, but they only play a role in assisting the fixing of 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 embodiment of 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 construction is to be carried out, and put the waterproof board laying trolley and lining formwork trolley in place in the tunnel;

[0011] After the wire rope net is deployed 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 and hanging 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 and hanging trolley;

[0013] 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;

[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 make it dense;

[0016] After the lining concrete reaches the set strength, remove the head formwork and dismantle the connection point 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 wire ropes extending along the length direction of the tunnel, and a plurality of annular wire ropes formed along the cross-sectional contour lines of the tunnel, and the nodes where the plurality of longitudinal wire ropes and the plurality of annular wire ropes intersect are fixedly connected to each other.

[0019] In some embodiments: the plurality of longitudinal steel wire ropes and the plurality of 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 plurality of longitudinal steel wire ropes and the plurality of 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, more than two 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: the reinforced concrete lining is pre-embedded with internal steel bars connecting each longitudinal steel wire rope of the steel wire rope net. When the position or number of the pre-embedded internal steel bars does not match the longitudinal steel wire rope, the longitudinal steel bars connecting one end of the longitudinal steel wire rope are implanted in the reinforced concrete lining, or a hole is drilled in the reinforced concrete lining to anchor one end of the longitudinal steel wire rope in the drilled hole of 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 arc-shaped 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 arc-shaped 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 30-100mm.

[0023] In some embodiments: a plurality of longitudinal wire rope avoidance grooves are provided on the head template, the longitudinal wire rope avoidance grooves are used to insert the longitudinal wire ropes, 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 steel wire rope net into n steel wire rope net sections along the length direction of the single steel wire rope net;

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

[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 template and the connection points between the waterproof board laying trolley and the steel wire rope net are removed;

[0028] Move the lining formwork trolley and waterproof board 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, one end of the next piece of wire rope net is connected 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 and hanging trolley, move the waterproof board laying and hanging 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. The construction method for preventing cracking and falling of the secondary lining of plain concrete in the present application transports a prefabricated wire rope net to the tunnel construction site to be constructed for the secondary lining, and puts the waterproof board laying trolley and the lining template trolley 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 the wire rope net is tightened from a relaxed state to a tensioned state, and then the waterproof board laying trolley is fixed;

[0034] After the wire rope net is tensioned in place, 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 preventing the secondary lining of plain concrete in the tunnel from cracking and falling off in the present application fully utilizes the advantages of high strength, good softness, suitability for traction and pulling, light weight, and convenience for transportation and installation and construction of steel wire ropes. 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 and hanging trolleys 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 steel wire ropes 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, and multiple lining trolley lengths can be laid at one time, reducing the workload of on-site laying and hanging, and convenient operation. Compared with steel mesh, steel wire rope nets have high tensile strength, good integrity, simple construction, and greatly reduce the use of steel materials, 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 drawings required for use in the description of the embodiments will be briefly introduced below. 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 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 diagram of the structure of the tunnel secondary lining and wire rope net according to an embodiment of the present application;

[0040] Figure 4 This is a schematic diagram of the structure of the wire rope net in the embodiment of the present application;

[0041] Figure 5 This is a schematic diagram of the structure 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 net; 2.1. Longitudinal wire rope; 2.2. Circumferential wire rope; 2.3. Wire rope buckle; 3. Reinforced concrete lining; 4. Internal steel bars; 5. Waterproof board laying trolley; 6. Longitudinal steel bars; 7. Wire rope anchoring clamp; 8. Rope clamp. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work 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 plain concrete secondary lining of a tunnel, which can solve the problem of cracking and falling of the plain concrete secondary lining of 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 put the waterproof board laying trolley 5 and the lining template trolley in place in the tunnel. In this step, the wire rope net 2 is prefabricated in the factory and then transported to the tunnel construction site. The wire rope net 2 is composed of longitudinal wire ropes 2.1 and circumferential wire ropes 2.2. The nodes where the longitudinal wire ropes 2.1 and circumferential wire ropes 2.2 intersect are firmly connected.

[0048] The mesh shape of the wire rope net 2 can be rectangular (such as square), rhombus and other regular polygonal shapes. The longitudinal length of each wire rope net 2 is generally not less than the length of a template trolley and a certain amount of surplus is considered, and the laying length range can also be extended once as needed.

[0049] The width of the wire rope net 2 should be as wide as possible to reduce the number of circumferential connection points between each wire rope net 2 while meeting the on-site construction conditions and transportation conditions. 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 that has been 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 wires 2.1 of the steel wire mesh 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 of 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 formwork trolley necessary 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 rear 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, and the wire rope net 2 needs to be tensioned in order to match the shape of the wire rope net 2 with the contour line of the tunnel cross section.

[0055] In this step, the waterproof board laying and hanging trolley 5 is mechanically pulled to move. 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. The waterproof board laying and hanging trolley 5 is fixed after the steel wire rope net 2 is tightened into place by pulling the waterproof board laying and hanging trolley 5.

[0056] Step 104: After the wire rope net 2 is tensioned, 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 the connection nodes of the wire rope net 2 are loose or the position is changed, repair and correct them.

[0057] After the wire rope net 2 is tensioned, 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 tensioned, check whether the connection between the nodes of the wire rope net 2, the connection between the mesh pieces, and the front and rear end connections are firm, and re-measure the positioning of the wire rope net to ensure that the positioning accuracy meets the requirements.

[0058] Step 105, move the lining formwork trolley to the wire rope net 2 laying area and fix it, install the head formwork at the end of the lining formwork trolley, the head formwork is installed at both ends of the lining formwork trolley, and the head formwork 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 compact it. 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 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 check 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 carry out the wire rope net 2 laying and lining concrete pouring construction operations until the secondary lining 1 of the tunnel is fully 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 and construction.

[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 the 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, and multiple lining trolley lengths can be laid at one time, reducing the workload of on-site laying and hanging, and facilitating operation.

[0065] Compared with steel mesh, wire rope mesh has higher tensile strength, better integrity, simpler construction, and greatly reduces the use of steel materials, reducing construction costs. Compared with the commonly used steel mesh and grid steel frame combination solution, this method can greatly save steel usage, and the benefits of saving project investment are very obvious.

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

[0067] By using the wire rope net 2 proposed in this method to replace the grid steel frame + steel mesh solution, only The steel wire rope weighs 13.2kg, and the amount of steel used 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 a plain concrete secondary lining of 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 lines 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 annular steel wire ropes 2.2 intersect.

[0069] Multiple longitudinal steel wire ropes 2.1 and multiple 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 100-200mm, preferably 150mm. The diameters of the longitudinal steel wire ropes 2.1 and the circumferential steel wire ropes 2.2 are 2-4mm, preferably 4mm, and the nodes where the multiple longitudinal steel wire ropes 2.1 and the multiple circumferential steel wire ropes 2.2 intersect are connected by tying or 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 a plain concrete secondary lining of a tunnel. In this construction method, the length of a single steel wire rope net 2 is greater than or equal to the length of the lining formwork 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, more than two steel wire rope nets 2 are laid in parallel in a circumferential direction in the tunnel, and the overlapping parts of two adjacent steel wire rope nets 2 are fixedly connected by rope clamps 8.

[0071] The longitudinal length of each steel wire rope net 2 in the embodiment of the present application is generally not less than the length of a lining template trolley, and a certain amount of surplus can be considered, and the laying length range can be extended as needed. According to the on-site construction organization, the length of multiple lining plates can be laid at one time. The width of the steel wire rope net 2 should be as wide as possible to reduce the number of circumferential connection points between each steel wire rope net 2 while meeting the on-site construction conditions and transportation conditions. The width of the steel wire rope net 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 an annular 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 by annular steel wire ropes 2.2, and the connection method is any one or more of the pressing method, the binding method, and the 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 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 a plain concrete secondary lining of a tunnel, wherein the reinforced concrete lining 3 of the construction method has internal steel bars 4 pre-embedded therein for connecting the longitudinal steel wires 2.1 of the steel wire mesh 2, and a portion of the internal 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 on 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, 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 a plain concrete secondary lining of a tunnel, wherein a plurality of steel wire rope anchoring clamps 7 for connecting each longitudinal steel wire rope 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 of the construction method.

[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 wire ropes 2.1 of 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 steel wire rope 2.1 is connected to the waterproof board laying trolley 5 through a reserved hole or a wire rope anchoring clamp 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 30-100mm, preferably 50mm, to avoid the wire rope net 2 being too close to the outer wall of the lining formwork trolley to expose 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 a plain concrete secondary lining of a tunnel. A plurality of longitudinal wire rope avoidance grooves are provided on a head template of the construction method. The longitudinal wire rope avoidance grooves are used to insert longitudinal wire ropes 2.1. 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.

[0080] The end plate is provided with a plurality of longitudinal steel wire rope avoidance grooves, which are used to prevent the end plate from blocking the end of the waterproof board laying trolley 5, and thus preventing the end plate from interfering with the longitudinal steel wire rope, thereby affecting the installation and fixation of the end plate. When the longitudinal steel wire rope 2.1 is placed in the longitudinal steel wire rope avoidance groove, the position accuracy of the longitudinal steel wire rope 2.1 can be 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 a plain concrete secondary lining of 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 a 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, where 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 fixations of the two ends of the single-piece steel wire rope net 2 can be reduced.

[0083] After the wire rope net sections of the single wire rope net 2 are all poured with lining concrete, remove the head template and the connection points 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 wire rope net 2 in the tunnel, one end of the longitudinal steel wire rope 2.1 of the next steel wire rope net 2 is connected end to end with the longitudinal steel wire rope 2.1 of the previous steel wire rope net 2. After the other end of the longitudinal steel wire rope 2.1 of the next 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 steel wire 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: the pressing method, the tying method, and the clamping method. The pressing method is to insert the ends of the adjacent circumferential steel wire ropes 2.2 into an oblong aluminum alloy sleeve and press them with a press; the tying method is to overlap the adjacent circumferential steel wire ropes 2.2 to be connected for a certain length, and then use thin iron wires to wrap and fix the overlap area; the clamping method is to bend one or both ends of the circumferential steel wire ropes 2.2 into a ring, and then use a rope clamp 8 to tighten the rope end with the ring.

[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. The construction method for preventing cracking and falling of the secondary lining of plain concrete in the present application transports the prefabricated wire rope net 2 to the tunnel construction site where the secondary lining 1 is to be constructed, and puts the waterproof board laying trolley 5 and the lining template trolley in 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 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 waterproof board laying trolley 5 is fixed after the wire rope net 2 is tightened from a relaxed state to a tensioned state;

[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 laying area of ​​the wire rope net 2 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 preventing the secondary lining of plain concrete in the tunnel from cracking and falling off of the present application fully utilizes the advantages of the steel wire rope, such as high strength, good softness, suitability for traction and pulling, light weight, and convenience for 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 and hanging 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 the weight is light and can be transported in rolls, it is possible to realize factory-made large-scale steel wire rope nets 2, and multiple lining trolley lengths can be laid at one time, reducing the workload of on-site laying and hanging, and convenient operation. 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, reducing construction costs.

[0090] In the description of the present application, it should be noted that the terms "upper", "lower", etc. 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 the present application and simplifying the description, rather than indicating or implying 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 the present 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 it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present 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 only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such 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 including 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, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0092] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

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 formwork 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) that has been constructed in the tunnel, and the other end is connected to the waterproof board laying trolley (5); The waterproof board laying and hanging 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 and hanging 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 make it dense; 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 formwork trolley and the waterproof board laying trolley (5) are moved to the next steel wire rope net (2) laying area to carry out the steel 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 as claimed in 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, and the nodes where the plurality of longitudinal wire ropes (2.1) and the plurality of circumferential wire ropes (2.2) intersect are fixedly connected to each other.

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 tying 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 as claimed in any one of claims 1 to 3, characterized in that: The length of a single 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 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 as claimed in 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 quantity of the embedded internal steel bars (4) does not match the longitudinal steel wire rope (2.1); A longitudinal steel bar (6) connected to one end of a longitudinal steel wire rope (2.1) is implanted in the reinforced concrete lining (3); Alternatively, a hole is drilled in the reinforced concrete lining (3) and one end of the longitudinal steel wire rope (2.1) is anchored 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 as claimed in claim 2 or 3, characterized in that: A plurality of steel wire rope anchoring clamps (7) connected to each longitudinal steel wire rope (2.1) of the steel wire rope net (2) are arranged on the arc-shaped 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 arc-shaped guide rail matches the cross-sectional contour line of the tunnel and is 30-100 mm away from the outer wall of the lining formwork trolley.

7. A construction method for preventing cracking and falling of a plain concrete secondary lining of a tunnel as claimed in claim 2 or 3, characterized in that: The end plate is provided with a plurality of longitudinal steel wire rope avoidance grooves for inserting the longitudinal steel wire rope (2.1). The end plate 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 end plate.

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 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; 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 mesh section reaches the set strength, and the lining formwork trolley is moved to the nth wire rope mesh section and the lining concrete is poured.

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 end template and the connection points between the waterproof board laying trolley (5) and the steel wire rope net (2) are disassembled; Moving the lining formwork 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 steel wire rope net (2) in the tunnel, one end of the next steel wire rope net (2) is connected end to end with the previous steel wire rope net (2); After the other end of the next 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 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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