CN110593909A

CN110593909A - Tunnel secondary lining dismounting and replacing construction method

Info

Publication number: CN110593909A
Application number: CN201910995905.XA
Authority: CN
Inventors: 何开进; 李学刚; 张传军; 汪东京; 闫世巍; 秦小鹏; 齐保伟; 魏文慧
Original assignee: China Railway Tunnel Group Co Ltd CRTG; China Railway Tunnel Stock Co Ltd
Current assignee: China Railway Tunnel Group Co Ltd CRTG; China Railway Tunnel Stock Co Ltd
Priority date: 2019-10-18
Filing date: 2019-10-18
Publication date: 2019-12-20

Abstract

The invention discloses a tunnel secondary lining dismounting and replacing construction method, and aims to solve the problems of high tunnel secondary lining dismounting and replacing construction difficulty and high safety risk. The method comprises the following steps: performing lining reinforcing operation on the to-be-disassembled and replaced lining; arranging an isolation damping groove at the junction between the disassembled position and the undetached position; before the second lining is dismantled, constructing isolation grooves in the dismantling area and the reserved area, and completely cutting off the second lining concrete and the reinforcing steel bars; before the lining is removed, the surrounding rock behind the arch wall is subjected to radial grouting reinforcement; removing the second lining, removing the reinforced sleeve arch and reserving the primary support; if the thickness of the second lining is smaller than the original design 2/3, the first lining is disassembled and replaced, the original first lining is broken and expanded and dug by three steps, then the second lining is recovered, after the disassembling and replacing length of the second lining or the first lining reaches 12m, the second lining concrete is applied again in time, and the second lining is applied according to 10.5m/1 group; if the thickness of the two liners is larger than the original design 2/3, the two liners are directly recovered. The invention provides reference and guiding significance for subsequent analysis and treatment of the same type of diseases.

Description

Tunnel secondary lining dismounting and replacing construction method

Technical Field

The invention relates to the technical field of tunnel engineering, in particular to a tunnel secondary lining dismounting and replacing construction method.

Background

With the advance of urbanization construction, the highway relieves traffic pressure to a great extent, and provides convenience for life of people.

Along with the development of highway construction, highway tunnels are increasing. Many built or under-construction tunnels in China have secondary lining cracking and other diseases, particularly loess tunnels in western China have complex geological conditions and poor self-stability, and secondary lining cracking is caused by incomplete construction process and other factors, so that the durability and the bearing capacity of a lining structure are reduced, and deformation and even damage are easily generated under the action of surrounding rock pressure; meanwhile, the construction limit of the tunnel is invaded, so that the tunnel clearance is reduced, and the driving safety is influenced.

In the prior art, a conventional rack is adopted to be disassembled and replaced by three steps, so that the problems of high construction difficulty, high safety risk and the like exist.

Disclosure of Invention

The invention aims to solve the technical problems that the tunnel secondary lining dismounting and replacing construction method is provided, and the tunnel secondary lining dismounting and replacing construction method aims to solve the technical problems that in the prior art, the tunnel secondary lining dismounting and replacing construction difficulty is high, the safety risk is high and the like.

In order to solve the technical problems, the invention adopts the following technical scheme:

a construction method for detaching and replacing a secondary lining of a tunnel is designed, and comprises the following steps:

detecting the thickness of a secondary lining of the tunnel to be constructed, and when the thickness of the secondary lining is smaller than 2/3 of the original design, implementing the following steps:

(1) performing lining reinforcing operation on a to-be-disassembled and replaced second lining by adopting I-shaped steel, and arranging 3 steel frame locking ports at the ends of the reserved area for reinforcing;

(2) arranging an isolation damping groove at the junction between demolished and undedemolished, and drilling a partition hole with the depth of the hole being the original lining thickness; adopting a pneumatic pick to draw the groove, wherein the depth of the groove is the original lining thickness, and steel bars in the groove need to be completely cut off;

(3) before the lining is removed, the surrounding rock behind the arch wall is reinforced by radial grouting, and hollow grouting anchor rods and small grouting guide pipes are arranged in a staggered mode in the 120-degree range of the arch part; the side wall adopts hollow grouting anchor rods, is arranged in a quincunx shape, and is injected with cement paste;

(4) removing the second lining, and removing the reinforced sleeve arch, wherein the removal length is controlled within 3 m; breaking the steel pipe from top to bottom by adopting a hydraulic breaking hammer, and reserving primary support;

(5) removing and replacing the primary support, performing three-step removal, breaking and expanding excavation on the primary support, performing upper/middle step arch foot support by using the width after expanding excavation, performing primary support and replacement on an arch wall to form 2 steel frames each time, firmly welding a lower step steel frame and an original inverted arch steel frame by adopting channel steel, and performing next cycle removal and replacement after finishing the 2 steel frames;

(6) and (4) recovering the second lining, and after the second lining or the primary support replacement length reaches 12m, applying second lining concrete again in time, and applying the second lining according to a group of 10.5m/1 to obtain the concrete.

Preferably: in the step (5), when primary support primary spraying is carried out, concrete spraying operation is sequentially carried out in a segmentation mode, a slicing mode and a layering mode, the spraying sequence is from bottom to top, and the length of each segment is not more than 6 m.

Aiming at another situation, another tunnel secondary lining dismounting and replacing construction method is designed, and comprises the following steps:

detecting the thickness of a secondary lining of the tunnel to be constructed, and when the thickness of the secondary lining is larger than 2/3 of the original design, implementing the following steps:

(3) before the lining is removed, the surrounding rock behind the arch wall is reinforced by radial grouting, and hollow grouting anchor rods and small grouting guide pipes are arranged in a staggered mode in the 120-degree range of the arch part; the side wall is arranged in a hollow grouting anchor rod plum blossom shape, and is injected with cement paste;

(5) and (4) recovering the second lining, and after the second lining or the primary support replacement length reaches 12m, applying second lining concrete again in time, and applying the second lining according to a group of 10.5m/1 to obtain the concrete.

Preferably: in the step (3), the water-cement ratio of the cement paste for grouting reinforcement is 1: 0.4-0.5, and the grouting pressure is not more than 0.4Mpa

Preferably: when the second liner concrete is poured, the concrete is pumped within 60min after being stirred, and is pumped within 1/2 initial setting time, and the pouring is finished before the initial setting.

Preferably: in the concrete pouring construction, two sides of the trolley are correspondingly weighed and poured, and the height difference of concrete surfaces on the two sides is not more than 1.0 m.

Preferably: when the second lining is recovered, the concrete lining should be cured in time after being demoulded, and the curing time is generally 7-14 days and must not be less than 7 days.

Preferably: and the second lining is disassembled and replaced in a section jumping mode, the secondary lining is recovered in time after the second lining is disassembled for 1 group, an operation space of 2m is reserved, and the next group is disassembled and replaced in a section jumping mode.

Preferably: the number of the skip sections is more than 2.

Compared with the prior art, the invention has the main beneficial technical effects that:

1. the invention classifies the original lining thickness and the original initial branch crack damage condition: if the thickness of the second lining meets the original design 2/3, the original primary support structure is basically complete, and only the second lining of the arch wall is disassembled and replaced; if the thickness of the second lining does not meet the original design 2/3, and the original primary support structure is seriously deformed or damaged, the second lining of the arch wall and the primary support are disassembled and replaced; that is, only the second lining structure of the arch wall is removed, whether the primary support is removed or replaced is determined according to the thickness of the second lining or the original primary support condition, and the second lining structure is reinforced properly.

2. The implementation safety of the invention is high: the safety risk of the removal and the replacement mainly comes from the removal and the replacement of the primary support, but the invention avoids the removal and the replacement of a large number of primary supports, can avoid the safety risks of block falling, collapse and the like caused by the removal and the replacement of the primary supports, and ensures the safety of constructors.

3. The invention has strong applicability, can effectively save time and ensure the construction period: the grade of the two lining steel bars and the concrete is strengthened after the replacement, and the bearing capacity of the two lining structure can meet the requirement.

4. According to the method, the fore shaft steel frame is arranged at the non-demolished end for reinforcement, and the partition holes and the isolation grooves are arranged at the demolished and non-demolished parts, so that the stability and integrity of the secondary lining of the reserved area can be ensured.

5. The invention has simple construction process, less input mechanical equipment and high work efficiency, can effectively accelerate the operation cycle time, accelerate the construction progress and save the construction cost.

6. In the invention, the second lining is disassembled and replaced in a section-skipping manner, the secondary lining is recovered in time after the second lining is disassembled for 1 group (10.5 m), and an operation space of 2m is reserved; the next group is disassembled and replaced at the skip section (more than 2 groups), so that the protection of a newly made second liner can be enhanced.

7. The invention carries out safe and effective replacement of the two linings by means of arch sheathing, grouting reinforcement and the like, and reinforces the structure of the two linings simultaneously to ensure the stability and safety of the structure of the two linings, thereby providing reference and guiding significance for the subsequent analysis and treatment of diseases of the same type.

8. The implementation of the invention can improve the structural durability of the existing operation tunnel, provide technical support for the long-term safe operation of the tunnel, and improve the core competitiveness and profit level of enterprises.

Drawings

Fig. 1 is a schematic view of a step arrangement.

Fig. 2 is a structural view of an arch wall in the form of primary support and section exchange.

Fig. 3 is a structural view of a second lining of an arch wall with a changed section.

FIG. 4 is a flow chart of a radial grouting construction process.

FIG. 5 is a schematic view of a full-section reinforcement.

Fig. 6 is a schematic view of the primary support and replacement operation rack.

FIG. 7 is a construction diagram of the connection between the lower step steel frame and the original inverted arch steel frame.

FIG. 8 is a second construction drawing of the connection between the lower step steel frame and the original inverted arch steel frame.

Fig. 9 is a construction drawing for replacing the steel frame.

FIG. 10 is a flow chart of steel arch construction process.

FIG. 11 is a flow chart of a shotcrete construction process.

Fig. 12 is a flow chart of a waterproof layer construction process.

Fig. 13 is a schematic view of the sequence of replacing the second lining of the arch wall.

FIG. 14 is a diagram of the layout of the primary support measurement points after removal.

Fig. 15 is a photograph of a secondary liner/primary cured front arch reinforcement.

FIG. 16 is a photograph of an isolation eye and isolation trench at the removed and unremoved interface.

FIG. 17 is a photograph of radial grout reinforcement prior to secondary liner/primary removal.

Fig. 18 is a photograph of the upper step primary support steel frame.

Fig. 19 is a photograph of the middle and lower step with the steel frame replaced.

Fig. 20 is a photograph of a two-lined change.

Fig. 21 is a photograph of a two-lined flashing/rebar job.

Fig. 22 is a photograph of a second lining construction.

Detailed Description

The following examples are intended to illustrate the present invention in detail and should not be construed as limiting the scope of the present invention in any way.

The instruments and devices referred to in the following examples are conventional instruments and devices unless otherwise specified; the related reagents are all conventional reagents in the market, if not specifically indicated; the construction methods are conventional methods unless otherwise specified.

Example (b): tunnel secondary lining dismounting and replacing construction method

The implementation place is a fixed highway, the east-west transverse line-G30 of the national highway is connected with the components of a Huo highway, a TD3 standard Qin state tunnel is positioned at the west side of a Guangxi city gateway town, and 5 emergency stop belts, 6 pedestrian crossholes and 5 vehicle crossholes are arranged for a separated 4-lane highway tunnel. The ascending line origin-destination number SK162+ 180-166 +810, the tunnel total length 4630m and the maximum buried depth 184 m. Descending line origin-destination pile numbers XK162+ 250-XK 166+840, the total length of the tunnel 4590m and the maximum buried depth of 183.7 m. A 6.7m ventilation shaft 1 seat is arranged at 25m on the left side of the XK164+ 750. The project is started and constructed in 2007 and is operated in 2011 and in 6 months, the whole route is communicated. The design speed is 80 km/h, the net width of the tunnel is 10.25 m, and the net height of the tunnel is 5 m.

First, overall construction scheme

1. Arch wall is just propped up to tear open and is traded

1.1 construction scheme

K1+722-K1+727 is selected as a test section for primary support and replacement of the arch wall, and the section is mudstone, has a muddy structure, is poor in cementation and is easy to soften when meeting water, and belongs to extremely soft rock. The block falling or collapse is easy to occur after excavation, in order to reduce the face, prevent the collapse of surrounding rocks and ensure the construction safety, the operation bench is disassembled and replaced by a three-step method, and the height of an upper step is 2.88m, the height of a middle step is 2.50m and the height of a lower step is 2.52 m. The secondary lining is disassembled for 1 time by 2m, and the primary lining is disassembled for 1 time by 1-2 trusses.

The step arrangement schematic diagram is shown in FIG. 1; the initial support and replacement section of the arch wall is shown in figure 2.

1.2 construction sequence

Reinforcement before demolition (surrounding rock reinforcement grouting, arch sheathing pre-reinforcement and isolation groove) → second liner demolition and primary support demolition and exchange for the upper step → second liner demolition and primary support demolition and exchange for the left side middle step → second liner demolition and primary support demolition and exchange for the right side middle step → second liner demolition and primary support demolition and exchange for the left side lower step → second liner demolition and primary support demolition and exchange for the right side lower step (finding out the connection of the original inverted arch steel frame and the lower step steel frame) → second liner recovery.

2. Two-lining dismounting and replacing for arch wall

2.1 construction scheme

Selecting K1+663-K1+722 as a test section to disassemble and replace a second lining of the arch wall, wherein the disassembly and replacement of the second lining are not more than 4m each cycle, adopting groove jumping interval disassembly and replacement, and the interval of adjacent disassembly and replacement working areas must be larger than the lining distance of the original 2 plates; scanning the primary support section after the replacement, when the thickness of the secondary lining does not meet 2/3 (26 cm) of the original design thickness; chiseling or removing and replacing the primary support, and when the two linings are removed to reach the length of the one-mold lining, pouring the two linings on the full section by using the template trolley in time.

The second lining replacement section of the arch wall is shown in figure 3.

2.2 construction sequence

Reinforcement before demolition (surrounding rock reinforcement grouting, arch sheathing pre-reinforcement, isolation groove) → secondary lining demolition → primary support section scanning → waterproof and drainage construction → steel planting and two-lining steel bar installation → two-lining restoration.

Second, construction method

1. Arch wall is just propped up to tear open and is traded

1.1 Reinforcement before demolition

(1) And (3) reinforcing a locking steel frame: 3I 20b steel frame locking openings are arranged at the end of the reserved area before disassembly and replacement, the spacing is 0.75m, phi 22 steel bars are adopted for connection in the longitudinal direction, the circumferential spacing is 1m, and the stability and the integrity of the secondary lining of the reserved area are ensured.

(2) Arranging isolation holes and isolating grooves: before dismantling, arranging isolation damping grooves at the junction between the dismantled part and the undetached part, and arranging 3 rows of partition holes, wherein the longitudinal distance of the rings is 0.15m multiplied by 0.15m, the aperture is 42mm, and the hole depth is 500 mm; and (3) adopting an air pick to draw the groove, wherein the depth of the groove is the original lining thickness, the width of the groove is 30cm, and steel bars in the groove need to be completely cut off, so that the lining of a reserved area is prevented from being pulled and cracked when the lining is removed.

(3) Radial grouting reinforcement: before the lining is removed, the surrounding rock behind the arch wall is reinforced by radial grouting, R32 hollow grouting anchor rods and phi 42 grouting small ducts are arranged in a staggered mode in the 120-degree range of the arch part, and L is 4 m; the side wall adopts an R32 hollow grouting anchor rod, and L is 6 m; the longitudinal distance between the rings is 1.2m multiplied by 1m, and the rings are arranged in a plum blossom shape. Grouting anchor rod and grouting small conduit cement paste, the water cement ratio is 1: 0.4-0.5, the grouting pressure is not more than 0.4Mpa, and the designed grouting amount is generally reached according to a single pipe as an end standard. When the grouting pressure reaches the designed final pressure for not less than 20 minutes and the grouting amount still does not reach the grouting final amount, the grouting can be finished and the full grouting of the anchor pipe hole is ensured. So that a 'hard shell' is formed around the arch protection device to play the role of protecting the arch.

The flow chart of the radial grouting construction process is shown in figure 4. The full-face dismounting and reinforcing schematic diagram is shown in fig. 5.

1.2 setting up work platform

The steps are disassembled and replaced, the upper step and the middle step adopt operation racks, the distance between the top layer of the racks and the vault of the excavation surface is 1.8m, main upright posts and cross beams of the operation racks are machined by I18I-steel, accessories such as inclined struts and the like adopt I14I-steel, the racks are integrally of a portal structure as shown in the figure, and vehicles pass through the lower parts of the racks; all steel structural components are connected by welding, the left side and the right side are of a pull-out type structure, when the tunnel arch wall expansion excavation platform works, the inner pipe is pulled out to the tunnel arch wall expansion excavation surface, a reinforcing mesh with the diameter of 14mm multiplied by 20cm is paved on the inner pipe, the inner pipe is used as a personnel working platform, and when the tunnel arch wall expansion excavation platform moves, the inner pipe is retracted into the sleeve to prevent the arch wall from being hung and. The drawing structure adopts a 100mm steel pipe and an 80mm steel pipe sleeved in the steel pipe.

The primary support dismounting and replacing operation rack is shown in figure 6.

1.3, secondary lining demolition and primary support demolition and replacement

The second lining demolition and the primary support demolition are carried out on an upper step, a middle step and a lower step, and the opening position is selected at a position 3-5m away from the initial distance of the design demolition (so as to prevent the lining of the non-demolition section from cracking). The first demolition length of the second liner is 2m, and the subsequent demolition length is 1.2m (2 steel frame spacing). Firstly, removing a lining within a range of 2m by using a breaking hammer and removing 2 steel frames of the original support (divided into three steps), and then supporting 2 steel frames of I20b at a distance of 1 steel frame/0.6 m; the lower step steel frame and the original inverted arch I18 steel frame are welded firmly by adopting 25c channel steel. And (4) performing next cycle of dismantling and replacing after completing dismantling and replacing of the upper/middle/lower three steps by taking 2 trusses as a cycle.

The connection construction of the lower step steel frame and the original inverted arch steel frame is shown in figures 7 and 8.

After the replacement, the thickness of the second lining is changed to 45cm (originally designed 40 cm), the thickness of the primary support is changed to 26cm (originally designed 20 cm), and the original primary support needs to be expanded and dug by 21cm by considering 10cm reserved deformation. In order to avoid the limit invasion of newly-made primary support deformation, the secondary lining needs to be recovered in time.

The steel frame replacement construction steps are shown in fig. 9, and specifically include:

dismantling a support steel frame: and 2 steel frames (shown in figure 9, the number II and the number III are removed) are removed when the primary opening is supported in the initial stage.

And secondly, expanding and excavating to a designed position by using a breaking hammer or a pneumatic pick (expanding and excavating 81cm from the inner contour of the lining, and considering 10cm of deformation).

And thirdly, newly installing supports (steel frames numbered A, B as shown in the figure) again, wherein the spacing between the steel frames is 0.6 m/pin.

Fourthly, continue chiseling the original primary support and installing a new support (the steel frame numbered C as shown in figure 9)

And fifthly, continuously removing the lining with the length of 1.2 m.

Sixthly, dismantling the primary support steel frame (shown in figure 9) with the number of 'four'.

And seventhly, reinstalling the steel frame numbered with the number D.

The primary support construction method comprises the following steps:

(1) steel frame

The steel frame construction process flow is shown in figure 10.

The steel frame is installed after the initial spraying is finished. The steel frame adopts I20b, the spacing is 0.6 m/truss, C22 screw steel is adopted for the longitudinal connection between every two trusses, and the circumferential spacing is 1.0 m.

The connecting ribs and the steel frame and the connecting ribs are welded firmly.

Secondly, the steel frame is connected by bolts, the connecting plates are closely attached, the bolts must be screwed, and when the connecting plates cannot be closely attached, the steel plates must be used for welding tightly.

And thirdly, before the steel frame is installed, virtual ballasts and sundries under the sole of the foot are removed, and the arch foot must be placed on a firm foundation. Steel frame installation tolerance deviation: the transverse direction and elevation are +/-5 cm, the installation distance is +/-5 cm, and the verticality is +/-2 degrees.

Fourthly, the whole process of the measurer is measured and controlled when the arch is erected, the position and the elevation of the arch are adjusted in time, and the position and the elevation of the arch are ensured to meet the requirements.

(2) Lock foot anchor pipe

Anchor pipe arrangement

Each steel frame is provided with 6 groups of 12 phi 42 grouting locking anchor pipes with the length of 3m, and the distance between the anchor pipes and the connecting plate is within 50 cm.

Anchor pipe construction

Anchor pipe hole adopts the pneumatic drill pore-forming, and anchor pipe hole should have 15 ~ 30 degrees down the angle of inserting, adopts high-pressure wind to thoroughly clear the hole to anchor pipe hole after the pore-forming, then installs phi 42 little pipe, water injection mud, water cement ratio 1: and 1, welding the L-shaped rib and the steel frame firmly.

(3) Reinforcing bar net piece

Firstly, the reinforcing meshes with the diameter of 8 are arranged on the arch and the wall, and the distance between the meshes is 20 multiplied by 20 cm. The mesh size must meet the design requirements.

Secondly, the reinforcing mesh should be laid up along with the fluctuation of the sprayed surface, the gap between the reinforcing mesh and the sprayed surface is controlled to be about 3cm, and the thickness of the protective layer of the reinforcing mesh is not less than 1 cm.

And the lapping length of the reinforcing mesh is 1-2 mesh sizes, and the lapping mode is spot welding.

(4) Sprayed concrete

The arch wall is provided with C25 shotcrete with the thickness of 26 cm. A wet spraying process is adopted. The construction process flow is shown in figure 11.

Preparation work

a. And (4) checking the pipeline of the equipment, such as wind, water, electricity and the like, positioning the shotcrete machine, and performing test operation. The selected air compressor meets the requirements of the operating air pressure and air consumption of the jet machine; before the compressed air enters the jet machine, oil-water separation is carried out; the conveying pipe can bear the pressure of more than 0.8MPa and has good wear resistance; and good ventilation and lighting conditions in the operation area are ensured.

b. If the surface of the rock is affected by water gushing, water seepage or damp, the rock is treated according to different conditions before spraying. The large gushing water is preferably injected with concrete after grouting and water plugging; the small strand of water or the water leaked from the crack is preferably injected into the concrete after rock surface grouting or conduit drainage; the large-area wet rock surface is preferably made of strong-cohesiveness concrete, such as additive and admixture added to improve the performance of the concrete.

Injection operation

a. The concrete spraying operation is carried out in a segmentation, fragmentation and layering mode in sequence, the spraying sequence is from bottom to top, and the length of the segmentation is not more than 6 m. When spraying, the low-lying part is approximately sprayed flat, and then the spraying is sequentially layered from bottom to top and is carried out in a reciprocating manner. The thickness of the initial spraying is not less than 5 cm.

b. When the sprayed concrete is constructed in a segmented mode, an inclined plane is reserved for the sprayed concrete last time, the width of the inclined plane is 200-300 mm, and the concrete is sprayed after the inclined plane is washed and wetted by pressure water.

c. The split spraying is carried out from bottom to top, and the concrete between the steel frame and the wall surface is sprayed firstly, and then the concrete between the two steel frames is sprayed. The side wall shotcrete should be sprayed upward from the footing so that the rebound will not wrap into the final sprayed layer.

1.4.1 construction of waterproof and drainage System

(1) Construction of annular drainage blind pipe

A phi 100 semicircular drain pipe is annularly arranged between the tunnel primary support and the waterproof plate and is communicated with the longitudinal drain pipe at the position of a wall foot.

(2) Longitudinal drainage blind pipe construction

The longitudinal drainage blind pipes are longitudinally arranged outside the left and right wall feet of the tunnel, the longitudinal drainage blind pipes are phi 116HDPE double-wall perforated corrugated pipes, every 10m of the longitudinal drainage blind pipes are connected with the transverse drainage pipes of the inverted arch through a tee joint, and water accumulated on the back of the drainage waterproof layer is led to a central ditch.

And marking out according to the rule so that the position of the blind pipe is accurate and reasonable, and the slope of the blind pipe is consistent with the slope of the line.

(3) Waterproof board construction

An EVA waterproof board and geotextile (more than or equal to 350 g/m) with the thickness of 1.2mm are arranged between the primary support and the secondary lining²) As a waterproof layer. The process flow of the waterproof layer construction is shown in figure 12.

First, base surface treatment

Base surface treatment: and (3) roughly leveling the primary support before laying the waterproof layer, supplementing and spraying the side walls and the arch parts, and leveling bottom mortar. Cutting off the exposed anchor rods, grinding or plugging and leveling by cement mortar, and the like.

And (3) water outlet point treatment: before the waterproof board is laid, the surface of the primary support sprayed layer is subjected to water leakage treatment in time, and grouting water plugging or drainage pipe burying is adopted to directly drain water to the side ditch, so that the dryness of the base surface is kept.

② laying waterproof boards

The waterproof board adopts a nail-free laying method, the once laying length is determined according to the concrete circulating pouring length, and trial laying is carried out before laying, and then adjustment is carried out. The waterproof board is laid by adopting a nail-free hole, namely, the non-woven fabric is fixed to a preset position, and then the manual electric heat welding device is used for heating, so that the waterproof board is welded on the hot melt liner special for fixing the non-woven fabric.

Welding of waterproof board

The waterproof board seam is formed by adopting an automatic welding line of a heat sealing machine, the lapping width of the edges of two waterproof boards is not less than 10cm, the number of welding lines is 2, and the width of a single welding line is not less than 10 mm; when the longitudinal seam and the circumferential seam are crossed (cross seam), the root-flush part of the redundant lapping part outside the longitudinal seam is cut in advance, and the step is repaired into an inclined plane and leveled.

Construction technical measure for laying waterproof board

Before the waterproof board is laid, hard objects such as an anchor rod head exposed on the surface of the concrete lining, a steel bar tip and the like are cut off, and the uneven part needs to be sprayed flat first, so that the surface of the concrete is smooth; the local water leakage position needs to be treated first.

At least 20cm of lap joint allowance is reserved at the edge of the waterproof plate paved in sections, a suspension point is added at the section change position, the buffer surface is guaranteed to be closely attached to the surface of the concrete, and meanwhile, the waterproof plate is connected with the drain hole in a sealing mode. The distance between the waterproof plate lap joint and the lining construction joint is staggered by not less than 50 cm.

The waterproof board and the non-woven fabric are inflammable objects, and once the waterproof board and the non-woven fabric are ignited, a fire disaster is caused, so that fireworks are forbidden in a working area, and a fire fighting facility and a high-pressure water pipe are arranged for standby.

(4) Construction of water stop belt and water stop strip

A back-attached water stop belt is arranged at the circumferential construction joint, and a water stop strip (arranged in the middle of the thickness of the lining, embedded into an inverted arch 1/2 and exposed 1/2) is arranged at the longitudinal construction joint.

1.4.2 construction of reinforcing steel bars

(1) Joint rib mounting

Drilling phi 22 connecting rib holes, wherein the hole depth is not less than 30cm, the distance between the inner layer and the outer layer is 30cm, the longitudinal distance is 20cm, the embedded rib length is staggered by 80cm and 130cm, the condition that the joint of the steel bar with the same section is more than 50 percent, the welding length of the steel bar is not less than 10 days in single-side welding and not less than 5 days in double-side welding is avoided.

Positioning rib installation

The position of outer reinforcing bar is marked according to tunnel clearance section to the measurement group, and constructor joins the end according to the measurement group and installs the location muscle, ensures that outer reinforcing bar does not invade the tunnel clearance.

Two lining steel bar installation

Firstly binding inner layer steel bars, adopting phi 22 deformed steel bars as main bars and having an interval of 20cm, adopting phi 14 deformed steel bars as distribution bars and having an interval of 30cm, and adopting phi 8 coiled steel bars as stirrups.

Firstly, the steel bar installation is carried out in a segmented mode after the length of each construction cycle is determined, and the installation length of the steel bar installation is consistent with the length of the lining. The construction sequence of the reinforcing steel bars is as follows: the method comprises the steps of inner layer circumferential phi 22 steel bars → inner layer longitudinal phi 14 longitudinal bars → outer layer circumferential phi 22 steel bars → outer layer longitudinal phi 14 longitudinal bars → inner and outer layers of steel bars with phi 8 hooping → steel bar crossing point binding.

Secondly, measuring and positioning before binding the reinforcing steel bars, and determining the positions of the inner edges and the central lines of the reinforcing steel bars. The length of each ring of steel bars is determined according to the length of the joint bars, the fact that the steel bar joints are prevented from appearing on the same cross section after welding forming needs to be considered when the length is distributed, the steel bar joints on the same cross section cannot exceed 50 percent (the steel bar joints are regarded as the same cross section within 50 cm), and the distance between every two adjacent steel bar joints cannot be smaller than 35 d.

And thirdly, when the steel bar joint adopts lap joint electric arc welding, the lap joint end parts of the two steel bars are folded to one side in advance, so that the axes of the two jointed steel bars are consistent. The length of the double-side welding seam of the joint is not less than 5d, and the length of the single-side welding seam is not less than 10d (d is the diameter of the steel bar).

And fourthly, when the main reinforcement joint adopts side welding, the side bars adopt the steel bars with the same grade and diameter as the welded steel bars. The upper strips and the axes of the welded steel bars are on the same plane, and the length of the upper strips, such as the length of a double-sided welding seam is not less than 5d (d is the diameter of the steel bar), and the length of a single-sided welding seam is not less than 10d (d is the diameter of the steel bar).

Fifthly, welding seams of the steel bars need to be full, the width reaches 0.7d (d is the diameter of the steel bars), slag cannot be contained, and welding skins are removed.

1.4.3, pouring the second lining concrete

(1) Concrete production and transportation

The secondary lining adopts C30 reinforced concrete and adopts a 10.5m hydraulic template trolley.

Secondly, a concrete batching sheet is provided by a laboratory according to requirements to guide the site construction, and the theoretical mixing proportion is obtained through checking calculation and site tests. In the concrete construction process, when the moisture content of the aggregate changes, a laboratory must adjust the construction mixing ratio according to actual conditions and determine through tests.

And thirdly, uniformly mixing the secondary lining concrete in a mixing station, adopting a full-automatic metering forced mixer, and strictly operating construction ingredients according to a mixing ratio.

And fourthly, the homogeneity of the concrete should be kept during transportation, and no layering, no segregation and no slurry leakage are realized. When the concrete is transported to a pouring point, the requirement of slump is met.

Fifthly, pumping the concrete within 60min after stirring, pumping the concrete within 1/2 initial setting time, and pouring the concrete before initial setting.

(2) Pouring of concrete

Firstly, pouring is carried out in a layered mode, a chute or a string barrel is used for leading concrete to a No. 1 window of the trolley, after pouring is finished, the concrete is led to No. 2 and No. 3 windows, and the inclination and falling height of the concrete is not more than 2 m. If the slump of the pumped concrete is not enough during construction, water cannot be added without permission, and the problem should be solved by a method of adding a water reducing agent under the guidance of a technician.

Secondly, the concrete pouring is continuously performed, and when the concrete pouring is intermittent due to reasons, the intermittence time is shorter than the initial setting time or the remolding time of the front layer concrete.

And thirdly, in the concrete pouring construction, two sides of the trolley are symmetrically poured, and the height difference of concrete surfaces on the two sides is not more than 1.0 m. The two sides are provided with professional tamping personnel for uninterrupted tamping, and uniform tamping is required.

(3) Capping construction

When the roof is sealed, a specially-assigned person commands, the exhaust hole observer and a concrete pump driver need to be closely connected, the normal pumping is immediately stopped when slurry leaks from the exhaust hole, the pumping is controlled by inching, and the pouring safety is noticed. During the pouring and capping process, the concrete must be continuously supplied, the vent holes are inserted, and the capping process is noticed to ensure safety and capping compactness. After the capping is finished, the exhaust pipe is loosened and pulled out in time after the concrete is initially set.

2. Two-lining dismounting and replacing for arch wall

2.1 construction sequence

The secondary lining is disassembled and replaced in a jumping mode, the secondary lining needs to be recovered in time in order to avoid the limit invasion of primary support deformation after the secondary lining is disassembled, and the construction sequence is shown in figure 13.

2.2 construction method

(1) Two-lining removal

Firstly, a 30cm groove is used as a damping groove between a demolished section and an undedemolished section before demolition, the influence of demolition on the structure of the undedemolished section is avoided, the depth of the damping groove is the thickness of a secondary lining, and secondary lining concrete, reinforcing steel bars and the like are cut off once during cutting.

Secondly, disturbance to surrounding rocks and primary supports is reduced as much as possible during dismantling, in order to ensure safety, a hydraulic breaking hammer is used for breaking and dismantling, and after loose objects and dangers are eliminated, residual lining blocks are manually removed one by an air pick. And removing the waste materials such as the concrete, the reinforcing steel bars and the like after lining, dumping the concrete to a ballast yard by using a mucking truck, and transporting the reinforcing steel bar waste materials out of the tunnel to be stacked to a waste shed.

And thirdly, when the construction is dismantled, a 15cm wide groove is utilized to cut and divide the dismantling section supporting structure, the working units are 1-2 m, and the two lining steel bars are cut off once during cutting, so that the influence on the adjacent section structure during dismantling is avoided.

(2) Two-liner recovery

After the lining is removed, the measuring group scans the section in time, an original primary support section diagram is obtained after scanning, and the engineering department determines the next construction measure according to the section scanning condition; and monitoring measuring points are distributed in time and distributed according to a 3m section, and monitoring is not less than 2 times every day. The deformation of the lining after being removed is not abnormal, the convergence deformation rate of the primary support is less than or equal to 0.2mm/d, and the next construction can be carried out. If the deformation is large and the stability cannot be realized in a short time, the engineering department immediately reports to the owners and the design houses, and the next construction measure can be taken through the survey of four parties.

The construction process of water prevention and drainage, reinforcing steel bars and two lining concretes is the same as the above.

The actual construction of the construction site is shown in FIGS. 15-22.

Third, the construction points and cautions

1. The principles of firstly arching, then wall-building, replacing along with disassembling, firstly reinforcing, then disassembling, less disturbance, frequent measurement and early looping are strictly followed in the disassembling construction.

2. Measures should be taken during construction to ensure reliable connection of the inverted arch steel frame and the steel bars with the arch wall steel frame and the steel bars, such as bar planting, appropriate chiseling of inverted arch concrete and the like.

3. When the initial support and the inverted arch construction section reach the length of a formwork lining, a full-section pouring secondary lining is timely adopted by the formwork trolley, and the interval between adjacent dismantling and replacing working areas must be larger than the distance between the original 3-plate linings.

4. If the early stage R32 hollow anchor rod grouting effect is poor in the construction process, a method of leading a small conduit can be used for carrying out remediation treatment.

5. In the tunnel excavation process, the main mode of excavation is mainly knocking by an impact hammer, and then is carried out with manual assistance, and if necessary, chemical agents can be used for carrying out static crushing, and blasting construction is strictly forbidden.

6. The whole course of the dismantling operation strictly prohibits the cross operation, the operation must be segmented and operated in a flow mode, protective facilities are arranged at two ends of a dismantling operation area, a specially-assigned person is arranged to watch, the entering of non-operating personnel is strictly prohibited, and any person cannot enter a section with the danger of object falling.

7. The operation platform is dismantled, the operation platform is required to be firm and reliable, the protective railing and the protective net are arranged, and safety belts are required to be fastened for personnel working aloft.

8. During the demolition construction, the monitoring frequency is increased, and the settlement, deformation and cracks of the lining and the development of the pavement are observed and analyzed in time.

9. And feeding back data in time to guide construction. If the displacement is too large or the displacement rate is too high, the disassembly is immediately stopped, the reason is checked, and the construction safety is ensured.

10. The interval between the measured sections can be properly encrypted in the section with serious lining damage or the section with abnormal change of monitoring data.

11. And a full-time safety worker is required to be arranged during the dismantling process, so that the safety is ensured.

Fourth, construction monitoring and measuring

1. Measuring point arrangement

In the dismounting and replacing process of the section to be dismounted and replaced, the measuring sections are arranged according to 5-10 m sections, the measuring frequency is 1-2 times per day, and the deformation condition is accurately mastered. And (4) burying points again in the removed and replaced sections, and arranging according to a section of 5 m. And measuring the peripheral three-dimensional deformation of the tunnel by adopting a free station setting and non-contact method of a total station. The reflection measurement points (including reference points) are comprised of a reflective membrane and a target. The size of the reflective film is 60 x 60 mm.

A convergence measuring line is arranged on each excavation step strictly according to design requirements, a side line sinks at the vault, and the whole ring of the primary support of the tunnel is 4 side lines and 7 measuring points (3 measuring lines and 5 measuring points at the step method removal and replacement section). The measurement point placement is shown in the preliminary bracing measurement point placement diagram of fig. 14.

And after the replacement, the observation on vault settlement and peripheral convergence is enhanced, the monitoring frequency is improved, data is summarized and analyzed in time, and large deformation is reported in time, so that measures are taken in time, and the condition of intrusion limit after the replacement is avoided.

2. Monitoring method and frequency

The monitoring method comprises the following steps: and (4) embedding a reflector plate on a measuring point for vault sinking and clearance convergence, and calculating the absolute value of deformation of each measurement by adopting a method of measuring coordinates by using a total station.

Monitoring frequency should meet the following requirements:

TABLE 1 measurement frequency (in terms of displacement speed)

。

Obtaining initial value

After the support is finished, installing measuring points according to requirements in time, and taking initial readings in time.

Quality assurance measures

(1) The construction technology management is strengthened, the technical responsibility system including a general engineer is strictly executed, and the construction management is standardized, normalized and programmed. The construction is organized strictly according to the standards, specifications and design requirements; and (5) carrying out technical background in time, and immediately solving the problem when finding the problem.

(2) And (3) insisting on a three-level recheck system of construction measurement, carefully protecting each measuring pile point, setting a guard pile at an important pile point which is possibly damaged in construction, and repeatedly checking construction measurement paying-off. The operation of cross-connecting piles is carefully carried out, and the sizes and the positions of the middle line, the level and the structure are ensured to be correct.

(3) The method comprises the following steps of performing strengthening test and detection work, wherein a working area is provided with a test room which is fully responsible for the feeding inspection test of raw materials such as steel, cement, coarse and fine aggregates, additives and the like in the working area engineering; the system is responsible for the design of the mix proportion of concrete and cement mortar, geotechnical tests and environmental monitoring; the device is responsible for manufacturing and construction control of concrete and mortar test pieces; the test device is responsible for the calibration and the daily maintenance of test instruments and equipment; and the test data collection, arrangement and filing are carried out.

(4) Various inspection, measurement and test instruments and equipment used for construction are checked and verified regularly, and the precision and the accuracy of the instruments and equipment are ensured.

(5) Before grouting, the drilling grouting equipment is checked to ensure normal operation of the equipment in the grouting process so as to avoid influencing the grouting quality.

(6) The prepared slurry is prepared immediately after use, the residual slurry is poured out, and the slurry storage barrel is cleaned.

(7) And in the grouting process, the change of grouting pressure and the grouting amount of a grouting pump is observed at any time, the grouting condition is analyzed, pipe blockage, slurry leakage and slurry leakage are prevented, and grouting records are made.

(8) And (3) dismantling the arch frame, immediately spraying concrete to seal the rock surface, carrying out steel frame support, anchor, net and spraying combined support in time, immediately constructing an inverted arch, and measuring, feeding back and correcting support parameters in time. The inverted arch is advanced and the two liners are reasonably close together.

(9) The allowable deviation of the spacing between the main reinforcing steel bars is +/-10 mm, and the allowable deviation of the layer spacing between the double rows of reinforcing steel bars is +/-5 mm; the allowable deviation of the spacing of the distributed steel bars is +/-20 mm; the allowable deviation of the stirrup spacing is +/-20 mm.

(10 construction is carried out according to the mixing proportion provided by a laboratory strictly, the slump of concrete is strictly controlled in the construction process, and phenomena of segregation, slurry leakage, mold running and the like are strictly forbidden during concrete pouring.

(11) The height difference of the concrete pouring surfaces on the two sides in the concrete pouring process is preferably controlled within 50cm, the concrete pouring speed is reasonably controlled, and the concrete cannot directly flow to the surface of the waterproof plate to the pouring position when being poured so as to prevent the concrete from being separated.

(12) When the inserted vibrating rod is displaced in the concrete, the inserted vibrating rod is required to be pulled out vertically and slowly, so that the inserted vibrating rod cannot be dragged in the concrete horizontally.

(13) And curing the concrete lining in time after demoulding, wherein the curing time is generally 7-14 days and is not less than 7 days.

While the present invention has been described in detail with reference to the drawings and the embodiments, those skilled in the art will understand that various specific parameters in the above embodiments can be changed without departing from the spirit of the present invention, and a plurality of specific embodiments are formed, which are common variation ranges of the present invention, and will not be described in detail herein.

Claims

1. A tunnel secondary lining dismounting and replacing construction method comprises the following steps:

2. The tunnel secondary lining dismantling and replacing construction method according to claim 1, characterized in that: in the step (5), when primary support primary spraying is carried out, concrete spraying operation is sequentially carried out in a segmentation mode, a slicing mode and a layering mode, the spraying sequence is from bottom to top, and the length of each segment is not more than 6 m.

3. A tunnel secondary lining dismounting and replacing construction method comprises the following steps:

4. The tunnel secondary lining dismantling construction method according to claim 1 or claim 3, characterized by: in the step (3), the water-cement ratio of the cement paste for grouting reinforcement is 1: 0.4-0.5, and the grouting pressure is not more than 0.4 MPa.

5. The tunnel secondary lining dismantling construction method according to claim 1 or claim 3, characterized by: when the second liner concrete is poured, the concrete is pumped within 60min after being stirred, and is pumped within 1/2 initial setting time, and the pouring is finished before the initial setting.

6. The tunnel secondary lining dismantling and replacing construction method according to claim 5, characterized in that: in the concrete pouring construction, two sides of the trolley are correspondingly weighed and poured, and the height difference of concrete surfaces on the two sides is not more than 1.0 m.

7. The tunnel secondary lining dismantling construction method according to claim 1 or claim 3, characterized by: when the second lining is recovered, the concrete lining should be cured in time after being demoulded, and the curing time is generally 7-14 days and must not be less than 7 days.

8. The tunnel secondary lining dismantling construction method according to claim 1 or claim 3, characterized by: and the second lining is disassembled and replaced in a section jumping mode, the secondary lining is recovered in time after the second lining is disassembled for 1 group, an operation space of 2m is reserved, and the next group is disassembled and replaced in a section jumping mode.

9. The tunnel secondary lining dismantling and replacing construction method according to claim 8, characterized in that: the number of the skip sections is more than 2.