The lining trolley is a necessary equipment in the secondary lining of the tunnel construction process and is used for the concrete lining construction of the tunnel inner wall.

Lining trolleys are indispensable non-standard products for secondary lining during tunnel construction. They mainly include simple lining trolleys, hydraulic automatic walking lining trolleys and grid-type lining trolleys. The hydraulic lining trolley can be further divided into side top arch type, round pin beam type, bottom die pin beam type, round passing type and so on. In the construction of hydraulic tunnels and bridges, lifting slipforms, jacking slipforms and turning forms are also commonly used.

Operating regulations for lining trolleys

(1) Before the trolley works, do a good job in the inspection and grounding of the trolley, check the power phase sequence and leakage protection devices to avoid reverse running caused by the trolley leakage and the motor reverse.

(2) The operator must be trained and familiar with the performance, structure and principle of the lining trolley, and only after passing the examination and obtaining the operation certificate, can the operator operate.

(3) Operators should fasten their straps when working at heights, and pay attention not to drop tools and other objects to hurt people.

(4) Check that the rail spacing must meet the requirements, and the plywood and sleepers should be intact. There are no dangerous rocks and obstacles in the direction of the trolley, and the mechanical braking system is intact. After confirming that each department is intact, go ahead and sound the horn.

(5) When the trolley is walking, someone should direct it. Protective posts should be set at the top, rear, left, right, and top of the trolley. Operators should obey instructions and strictly guard their posts.

(6) Carry out the P system and make sure that the front and back are sturdy. After being fully prepared, the commander shall use the correct gesture or whistle to prevail and ring back to warn before starting. Before passing through the formwork, you must stop and inspect all parts for obstacles, and then start to pass when it is confirmed to be correct.

(7) The lifting equipment of the trolley must comply with the regulations and must not be replaced arbitrarily, and someone is responsible for the operation. Lifting must be carefully checked by various departments. It is strictly forbidden to stand under the equipment when lifting. Make sure that the lifting equipment is working before working.

First, lining construction preparation

1. The tunnel lining trolley formwork and bracket have sufficient strength, rigidity and stability, the formwork trolley is finished, and the design requirements are met by the commissioned section size;

2. The initial support of the tunnel has been completed, and the surface flatness, clearance size, concrete strength, and bolt pull-out resistance have been accepted and accepted, and the initial support deformation is basically stable after construction;

3. The specifications and quality of various drainage and drainage materials such as circumferential drainage blind pipes, non-woven fabrics and waterproof boards meet the design and specification requirements, and the quantity meets the construction needs;

4. Professional construction personnel conduct pre-job operation technical training;

5. Mechanical equipment such as walkable work bench, automatic running heat welder and welding torch are in place, and the performance status meets the construction needs;

Second, the initial test

1. After the initial support settlement is stable, the initial support clearance is tested to ensure the thickness of the lining.

2. Carefully inspect the base surface of the shotcrete, and there must be no sharp protrusions such as pipe fittings protruding from the steel bar. If it exists, it should be cut off and smoothed with mortar.

3. The angle of the tunnel section or the corner of the corner should be smeared into an arc of not less than 5mm.
4. There should be no clear water on the base of the tunnel. If there is clear water, it should be blocked or led by the breeding measures.

Third, blind tube installation

1. The circumferential drain pipe adopts φ50 double-wall perforated corrugated pipe wrapped with non-woven fabric. Each ring of the lining of the plate is provided with a ring directly connected with the longitudinal bellows by three-way connection. The concentrated water outlet is encrypted according to the size of the water; An outer non-woven perforated corrugated pipe with a diameter of φ100 is arranged on the side, and the longitudinal corrugated pipe and the inverted arch ring are connected by a tee and directly introduced into the central drainage ditch.

2. When the longitudinal blind pipe is installed, the longitudinal slope must be consistent with the slope of the line, and it should be fixed once every 1m to ensure that the position of the blind pipe does not change when the concrete is poured. The slope meets the design requirements.

3. Technical points of blind pipe construction

(1) Longitudinal through-drain blind ditch installation shall be scribed according to the design regulations, so that the position of the blind pipe is accurate and reasonable, and avoiding excessive undulation.

(2) The distance between the drainage blind pipe and the support shall not exceed 5cm, and the blind pipe shall be fixed by wire mesh with a spacing of 100cm.

(3) Drilling the concentrated water outlet point along the water source direction, then inserting a single centralized water diversion blind pipe into it, and sealing the surrounding with a quick-setting mortar to concentrate the groundwater from the pipe;

(4) The blind pipe joint is wrapped with the water-permeable material of the non-woven fabric to prevent concrete or debris from entering the blocked pipe.

(5) The overhanging part of the blind pipe is fixed with steel bars to prevent the position of the blind pipe from changing when pouring concrete.

Fourth, non-woven fabrics and waterproof boards

1. The technical indicators and technical performance of raw materials must meet the design requirements.

2. The laying of the non-woven fabric is laid from the center line of the vault of the working trolley to both sides, and then the non-woven fabric is fixed on the sprayed concrete surface with a nail with a thermoplastic round gasket. The fixed distance of the arch is 0.5m~0.8m, and the side wall 0.8m~1.0m, arranged in a plum pattern.

3, the non-woven fabric should be laid tightly, so that it can be closely attached to the surface of the shotcrete to avoid over-tightening or tearing to form a water storage point. The width of the non-woven fabric overlap is not less than 10 cm, and the longitudinal blind tube is wrapped around the arch.

4. The waterproof board is laid from the center line of the vault of the work trolley to both sides, and the side seam is welded and fixed with a hot seam welding torch and a thermoplastic round washer.

5, the waterproof board should be laid tightly, so that it can fully engage with the non-woven fabric and adhere to the surface of the sprayed concrete to avoid over-tightening and tearing or loosening to form artificial water storage points.

6. The width of the two waterproof boards is not less than 15cm. The joints of the waterproof board are welded by automatic double-slot hot-melt welding machine. The width of each weld is not 2cm. An air passage is left between the two joints after welding for air. The detector detects the weld.

7. Construction control points

(1) Remove the dust on the surface of the waterproof board before welding.

(2) If the waterproof board is damaged, it should be repaired in time. First take a small waterproof board and cut it into rounded corners. The distance between the edge of the patch and the damaged edge should not be less than 7cm. After removing the dust on the two waterproof boards, place it on the damaged part and then weld it with a manual electric fuser.

(3) The joint of the waterproof board should be staggered with the waterproof weakening parts such as the settlement joint, the construction joint and the concentrated water outlet of the surrounding rock.

Fifth, the grouting pipe is buried

1. The grouting pipe and the exhaust pipe are all made of φ30mm PVC pipe. The pipe body is equipped with plum-shaped overflow hole, the hole diameter is 2-3mm, the longitudinal spacing is 20cm, and the fixed strip is made of 40cm×10cm rectangular waterproof board. The grouting pipe and the exhaust pipe fixing strip are welded and fixed to the vault, the distance between the two pipes is 3-5 cm, and the spacing of the fixing bars is ≤80 cm. The PVC pipe is lengthened by direct head connection, the total length is equal to the length of the lining plus 20cm (exposed), and the exposed end should have a connecting pipe device.

2. When the steel bar is tied, the concrete block around the grouting pipe must be encrypted to prevent the grouting pipe from being crushed and destroyed due to the deformation of the steel bar during the pouring process.

3. When the second lining arch top end template is blocked, a specially processed end template is used. The end template is cut at one side, and the grouting tube and the exhaust pipe are passed through the groove to prevent the end die from being damaged and grouted. tube.

Sixth, steel processing and installation

1. The performance of the steel raw materials shall be checked to ensure that the raw materials are qualified. At the same time, the processing and production process of the steel bars shall meet the design and specification requirements.

2, steel construction stakeout: the site with the total station, using five points to locate the position of the steel bar, that is: to establish a plane coordinate system with the center of the lining as the origin, by controlling the center point of the arch table template, the arch lining the trolley The template is the same as the two junction points of the side wall template and the foot points of the two wall templates to control the position of the steel bars.

3. First, the measuring personnel use the coordinate loft to determine the center point of the two steel bars in the range of the self-made trolley in the leveling layer and the vault waterproof board, determine the normal direction, and ensure the verticality of the positioning steel bar and the inverting arch. Reserve the accuracy of the reinforcement connection. The verticality of the steel bar binding is determined by the method of three-point hanging balls.

4. According to the measurement data, the positioning steel bar is arranged, the longitudinal ring spacing of the positioning ribs is 3m*3m, and the longitudinal positioning ribs are located on the side of the waterproof board. When the circumferential main rib is in place according to the specified spacing of the design, it is fixedly connected with the positioning steel bar. The longitudinal reinforcement is then tied as designed.

5. Before the lining inner layer steel bar is in place, it must be based on the measurement of the given midline, elevation, normal and other measurement data, accurately install the steel bar positioning and support steel bars (steel pipes), and evenly distribute the inner layer main ribs on the supporting steel bars (steel pipes). Then, the inner layer longitudinal ribs are evenly arranged at the design pitch and tied tightly.

6. After the main rib is tied, the stirrups are installed, and the stirrups should be tied tightly.

7. After the steel bar is tied, check the contour size according to the height of the center line. After passing the test, hang the 55mm thick ram block on the inner layer of steel (the lining block is prefabricated with the lining of the same level) to ensure the net protective layer of the steel after concrete filling. thickness.

8. Construction control points:

(1) When the steel bars are tied, it is strictly forbidden to damage the waterproof board. When the steel bars are welded, the waterproof board is covered with a fireproof board to prevent the burned waterproof board.

(2) The length of the weld joint of the steel bar should meet the requirements, the double-sided welding is 5d, and the single-sided welding is 10d (d is the diameter of the steel bar).

(3) The steel bar binding must be tied tightly, especially the stirrups, to avoid scattering during concrete pouring and vibrating.

(4) Pre-bending of steel bars needs to be carried out outside the hole, and the transportation of steel bars is carried out by mechanical transportation to ensure that the steel bars are not deformed after bending.

(5) The lining steel bars are arranged on the gantry, which is a high-altitude operation, and workers need to take safety protection measures.

Seventh, the template trolley is in place

1. The track is laid before the trolley is in place, and the sleepers are laid under the track. The distance between the sleepers is 50cm. The center line of the background car roof board coincides with the center line of the tunnel.

2. After the trolley is in position, the rail clamp is locked to fix the trolley on the rail, and then the vertical cylinder and the lateral cylinder are alternately activated to make the template stand at the design position.

3. The trolley is polished and brushed off the mold before adjusting the height.

4. The trolley passes the measurement and positioning. During the measurement, the elevation of the vault design and the distance from the two sides of the side wall to the center line are mainly detected. To meet the settlement requirements, the outer elevation of the vault template of the lining trolley is higher than the net elevation of the tunnel vault by 5 cm. The angle of the arch on both sides of the trolley is 5cm larger than the design outline. After the measurement of the clearance of the trolley reaches the requirements, the reinforcement is locked, the vertical and horizontal jacks are locked, and the reinforcement support is installed to ensure the stable positioning of the trolley.

5. Construction control points:

(1) The movement of the trolley is directed by a special person in the process to avoid collision between the trolley and the pipeline and equipment. At the same time, the person grasps the brake to prevent the trolley from slipping and rushing.

(2) During the reinforcement process of the trolley, carefully inspect each kilogram and cylinder to avoid running the die or the wrong platform due to the bias caused by the individual jacks.

Eighth, install the water stop

1. Buried waterstop installation

(1) Cut the length of 60cm Φ10 steel bar into a steel bar, and bend one end of the steel bar into a circular hook.

(2) A hole of Φ12 is drilled in the head plate at a distance of 50 cm along the contour line of the lining design.

(3) Insert the formed Φ10 steel bar from the side of the concrete to be molded to the other side, the inner test card is tightly closed to the water belt, and the other half of the water stop is flat on the stop plate and fixed by wire. .

(4) After the mold concrete is solidified, remove the stop head plate, straighten the water stop belt to the center steel bar, and then bend the Φ10 steel bar sleeve on the water stop belt.

(5) If the lining trolley is equipped with a flip-type steel-wood composite end die, the inverted rubber-stopped water-stopping belt is accurately positioned by flipping the hinge.

2. Externally attached waterstop installation

(1) According to the deformation joint and the mileage of the construction joint, use the total station to determine the exact position of the waterstop installation on the waterproof board and mark it;

(2) Wipe the waterproof board and the back-mounted water stop with a smooth surface;

(3) Bond the waterstop to the specified position with an adhesive.

3. Water stop installation

(1) Install a hard plastic strip with a width of half the width of the water stop strip on the concrete surface where the water stop strip is required, so that a concrete groove is formed after the concrete is poured, and the water stop strip is embedded in the reserved tank half in the next construction. Exposed half.

(2) After the first concrete pouring of the formwork is removed, the construction joint should be chiseled, and then the rafts on the joint surface should be removed with tweezers or wire brushes. After cleaning, keep it moist and brush the cement slurry 2~5mm thick. After the surface is dry, apply the adhesive on the bottom surface of the water-swellable water-stop strip and the water-stop strip. The adhesive should use the matching products. The liquid is volatilized for a period of time before being pasted.

(3) When the water-expansion water-stopping strip is extended, the joints shall be overlapped by means of overlapping methods, and the butt joints shall be dense and shall not be disengaged.

4. Construction control points

(1) The installation position of the waterstop must meet the design requirements.

(2) The water stop belt shall be connected at the site, and shall be vulcanized and cold bonded by hot pressing. The joint shall be smooth and smooth, and the tensile strength shall not be less than 90% of the base metal.

(3) When tying the steel bars and the formwork, the waterstop must be fixed firmly to avoid displacement when pouring the concrete.

(4) Due to the advancement of the inverting arch and the small side wall, the buried waterstop in the small side wall section should be 15cm higher than the longitudinal construction joint to be docked with the buried waterstop of the post-casting arch wall.

(5) If the water stop strip has a swelling phenomenon, it shall not be used.

Ninth, the end template installation

1. Lining at the contact part of the small side wall, the bottom mold of the lining trolley directly abuts the longitudinal construction joint of the small side wall.

2. The first set of tunnel lining construction requires two ends for sealing.

3. The front end of the lining trolley is generally connected with the lining of the previous rafter to form a closed end. The rear end of the lining trolley is open, and the construction personnel need to assemble the independent template to form the rear end. The closed end of the head.

4. When the end is closed, the longitudinally connected steel bars are reserved. The method of inserting steel bars between the plug plates is reserved, and the spacing and length of the inserted steel bars should meet the requirements of the specification.

Tenth, concrete pouring

1. The perfusion window is arranged symmetrically on the upper, middle and lower layers, with 4 windows on each side of each layer, and the layers are interlaced with the layers. The window size is 0.5*0.5m. Three vertical pumping interface pipes are arranged on the longitudinal section of the highest point of the arch of the trolley, which are arranged at the two ends and the middle part of the trolley.

2. The secondary lining is filled by the concentrated pumping material of the pump pump, and the chute is made of iron. The length of the chute can be adjusted to meet the needs of the concrete conveying windows of the upper, middle and lower concrete pouring windows. According to the distance between the center line of the line and the perfusion window, the length of the chute is determined and fixed by the secondary lining trolley. The chute must be firmly fixed and can support the impact of concrete gravity and concrete pouring.

3. The concrete pouring sequence is the secondary lining of the poured section from the bottom to the top in the direction of the face, and the left and right symmetry is poured window by window, vibrating by window.

4. According to the secondary lining structure, the vibration of the concrete is divided into two parts. The lower part is the part below 0.2m below the lower edge of the third layer window of the trolley, which is mainly the range of the inserted vibrator; the plug-in vibrator cannot be completely covered at both ends and corners of the trolley. Five attached vibrators are added to the side to assist in vibrating. The upper part of the arching line is the range of the attached vibrator, and the attached vibrator is installed on the symmetrical stencil of the secondary lining trolley, and is arranged on the upper, middle and lower layers.

5. In order to achieve the effect of the attached vibrator starting from the bottom to the top, it is necessary to centrally control the same layer attached vibrator.

6. When concrete is poured, the maximum falling height of concrete should not exceed 2m. The height difference between concrete before and after the trolley should not exceed 0.6m. The height difference of concrete pouring surface on the left and right sides should be controlled within 0.5m. It is strictly forbidden to cast more than 0.5m on one side. At the same time, the concrete pouring speed should be reasonably controlled. When pouring concrete, it should not directly rush to the surface of the waterproof board to the pouring position to prevent the concrete from being separated.

7. Construction control points:

(1) When the concrete is vibrated, the vibrating bar shall not touch the waterproof plate to prevent the waterproof plate from being damaged.

(2) The vibrator template has a certain amplitude. In order to avoid the offset of the trolley, the screw rods at both ends of the trolley are reinforced by diagonal bracing.

(3) Before the concrete is poured, carefully check whether the template trolley is in position. The inspection items include the space position and structural size of the trolley comply with the design requirements. The plug reinforcement is firmly locked in the running part, and the bottom support is firm and does not leak.

(4) In order to prevent the occurrence of cavities in the concrete pouring of the arch, the concrete slump should be controlled by 200mm. The slump should not be too large to avoid segregation or bleeding.

(5) When the concrete is poured to the working window 20cm, before the working window is closed, the concrete slurry residue and other dirt near the window should be cleaned, the release agent should be painted, and the sealing agent should be closed tightly to prevent the concrete surface from appearing on the window. Uneven patches and even slurry leakage.

Eleventh, concrete curing

1. After the lining concrete is demolished, the high-strength sprayer is used for timely maintenance to keep the concrete in a wet state.

2. The maintenance period meets the design and specification requirements.

The tunnel lining construction scheme of the inverting arch and the filling first in the lining is 2 to 3 holes wide from the excavation working face. Invert the arch first, then construct the side wall and arch ring to facilitate the overall force of the lining structure, and to open early, anti-collapse. At the same time, it can ensure the smooth flow of the road inside the cave, and it is very beneficial to do a good job in the drainage of the cave and do a good job in civilized construction. The application of the inverted arch will inevitably affect the operation of the vehicle. This adopts a simple anti-interference platform as a transitional passage to ensure the normal construction of the face. The fill uses a fixed length template. In the section where the section size is unchanged, the secondary lining of the side wall and the arch ring is constructed once by the integral steel mold lining trolley.

If the dimensions of the lining section change, a combined formwork is used. The combined formwork system consists of a steel arch, a longitudinal beam, a steel pipe inner support and a steel formwork. The steel arch is divided into two pieces by bolts to form a backing. When the section changes little, loosen the steel arch butt bolts, by adding or reducing the corresponding steel arches in the middle of the arches, and then tightening with bolts. Section change. The stringer is made of I16 I-beam and joined to the steel arch (I20) to enhance the integrity of the combined formwork. The steel formwork adopts CM03012 (width 300mm, length 1200mm, height 84mm), and the length of each lining is based on the construction plan of each section. Concentrated concrete mixing, concrete tanker transportation, pump pumping, and plug-in vibrator vibrating.

Tunnel lining construction technology

(1) Reinforcement production

A. Straightening and rust removal of steel bars:

The surface of the steel bar should be clean, and the surface oil stains, stains, scales, scales, etc. should be removed before use.

The steel bar is straight and there is no partial bending. The deviation of the center line of the steel bar cannot exceed 1% of its total length.

After the steel bar is straightened on the straightening machine, the surface damage shall not reduce the cross-sectional area of ​​the steel bar by more than 5%.

B. The bending of the steel bars and the hooks at the ends shall comply with the design and specification requirements:

The end of all the round bars of the stretched surface shall be a semi-circular hook of 180°. The inner diameter of the hook shall not be less than 2.5d, and the straight end of the hook end shall be no less than 3d.

C. The minimum turning diameter of Class II steel bars when they are rotated by 90° according to the design requirements meets the following requirements:

When the diameter of the steel bar is less than 16 mm, the minimum turning diameter is 5 times the diameter of the steel bar.

When the diameter of the steel bar is larger than 16 mm, the minimum turning diameter is 7 times the diameter of the steel bar.

The bent steel bar is bent into a smooth curve with a radius of curvature not less than 10 times the diameter of the steel bar (light round bar) or 12 times (ribbed grade II bar). The stirrups made of round steel bars have hooks at the ends, and the length of the hooks meets the technical requirements.

The allowable deviation of the steel bars after processing shall not exceed the values ​​specified in the specification.

The steel bar is responsible for the application according to the technical requirements. The specifications, model and length of the steel bar meet the design requirements. The technical supervisor and the quality inspection engineer are responsible for inspection and acceptance, and check and make records at any time.

D. Connector

The joints of the steel bars are flash butt welded, and when flash butt welding is not possible, mechanical connections are used. Cross-connection of steel bars, using contact spot welding, manual arc welding is not suitable. The joints of the welded steel bars shall be cleaned of the rust, paint, grease and the like in the welding range.

In order to ensure the quality of joints of flash butt welding, two cold bends and two tensile test pieces shall be tested according to the actual welding conditions before the welding or changing the type and diameter of the steel bars, according to the appearance quality of the joints of the test pieces. The welding parameters are verified by inspection and experiment. After the quality of the test welding and the welding parameters are selected, the welding can be carried out in batches. When there is doubt about the welding quality, the sampling will be carried out according to the actual situation.
All flash butt welded joints shall be visually inspected. There shall be no cracks or obvious burns on the surface of the steel bars. The joint bending angle shall not be greater than 4°, and the joint axis eccentricity shall not be greater than 0.1 times the diameter of the steel bars and shall not be greater than 2 mm.

For hot-rolled steel bars with a diameter of 10mm or more, when the joints are welded by lap or gang, they meet the requirements of the specification.

The electrode used for arc welding is used as specified in the design. When the design is not specified, it can be selected according to the specifications. In order to ensure the welding quality of the arc welding, before starting the welding (not before the shift) or each time changing the type, diameter, welding grade of the steel bar and changing the welder, especially in the unfavorable environment that may interfere with the welding operation, during the field welding Two tensile specimens are prepared in advance using the same material, the same welding operating conditions and parameters, and the test results are allowed to be officially welded when the tensile strength of the steel is greater than or equal to that of the steel.

The steel bars are tied with joints and meet the specifications. The steel joints are scattered. The following stress-reinforcing bars disposed in the “same section” shall have a cross-sectional area of ​​the joint that does not exceed 50% of the total cross-sectional area of ​​the stressed steel bar.

(2) Rebar installation

In order to ensure the thickness of the concrete protective layer and ensure the position of the steel bar is accurate, a concrete block with a strength not lower than the design strength is set between the steel bar and the formwork. The blocks are buried with iron wires and tied tightly with the steel bars, and are staggered and dispersed.

The installation position of the ribs, the spacing, the protective layer and the size and size of each part of the reinforcement are in accordance with the design drawings. The deviation shall not exceed the specifications.

The installed steel bars have sufficient rigidity and stability.

After the steel bar is tied, the technical supervisor shall carry out detailed inspection according to the design drawings and the standards of the construction specifications, and make inspection records. After the steel bar inspection is passed, the quality inspection engineer and the resident supervisor must check and confirm before proceeding to the next step.

(3) Formwork construction

A. After the completion of the invert arch excavation, the initial support construction of the invert arch is carried out in time. First spray and close, then hit the anchor rod, install the inverted arch steel frame, and then spray again to the design thickness to cover the steel frame. When there are conditions, after the initial spray sealing at the bottom, the vertical arch can be used for one vertical mold construction.

B. The side wall and arch lining adopts the integral formwork trolley. The secondary lining should be applied after the surrounding rock and initial support deformation are basically stable. When the deformation of the surrounding rock is large and the rheological characteristics are obvious, the initial support should be strengthened. It is also applied as an inverted arch and a secondary lining early. At the same time, the distance between the secondary lining and the face of the hand is in accordance with the requirements of the drawings or technical specifications. Under normal circumstances, it is not more than 200m, and the weak surrounding rock should be followed closely.

C. The surrounding rock and initial support deformation are basically stable and meet the following conditions:

The displacement rate of each test item is obviously converged, and the surrounding rock is basically stable;

The displacements that have been generated have reached 80% to 90% of the estimated total deformation;

The peripheral displacement rate is less than 0.1-0.2 mm/d, or the dome sinking speed is less than 0.07-0.15 mm/d.

(4) lining trolley manufacturing:

A. Formwork support The clearance under the truss door meets the requirements for large-scale equipment required for construction in front of the tunnel lining; the height of each platform of the truss should meet the construction requirements, which is conducive to workers’ construction work such as safety and tamping.

B. The overall template plate of the trolley consists of a panel, a supporting skeleton, an articulated joint, a working window, etc. When the lining section is large and the load is large, the supporting skeleton is made into a truss structure to meet the requirements of the strength and rigidity of the trolley. And try to reduce the number of plate joints.

C. In order to ensure the lining clearance, the outer diameter of the template should be appropriately expanded considering the amount of deformation. The thickness of the steel panel shall not be less than 8mm. Indirect seams of the plates shall be welded and polished.

D. The working window should be set at 2m, 4m, and the vault. The window size is 1250px×1250px, and it should be uniform.

E. The length of the tunnel lining trolley is 9m and 4.5m.

F. The hydraulic support and shrinkage system of the trolley formwork should be arranged reasonably to meet the needs of lining construction.

G. The lining trolley should meet the requirements of automatic walking and have a locking device to ensure accurate positioning.

(5) Prerequisites for concrete construction

A.The initial support of the secondary lining operation section and the waterproof board isolation layer and the circumferential permeable blind ditch have been qualified. The waterproof isolation layer of the hard rock section is at least 2 to 3 times longer than the second lining working surface. The dust on the surface of the waterproof layer should be removed and sprinkled with water.

B.The measurement work is meticulous and accurate, and the center line, elevation, section size and headroom size must meet the requirements of the specification.

C.According to the monitoring and measurement feedback information, the timing of the application of the secondary lining is scientifically determined.

D.The filling layer or the bottoming leveling layer on the inverting arch of the secondary lining operation section has been completed, and the groundwater has been properly routed; in order to facilitate the smooth collection of the foot part of the side mold of the trolley, when constructing the short side wall first, The elevation of the joint with the bottom of the side mould of the trolley and the distance from the centerline of the carriageway are in accordance with the calculated design value, and the allowable deviation is ±5mm; the construction joint has been processed according to the specifications, and the scum and accumulated water in the foundation part must be cleaned up.

E.The overall formwork lining trolley, transfer pump, transport vehicle, tamping machinery, etc. are in normal operation, and the equipment capacity meets the needs of tunnel second lining concrete construction.

F.The lighting, power supply, water supply and drainage systems of the secondary lining operation section meet the normal construction requirements of the lining; the ventilation environment is good.

(6) Construction process

A. All concealed works can only be concealed after the quality inspection and acceptance.

B. In order to ensure the quality of the lining project, the second lining construction of the general section of the tunnel (including the tunnel body, the open hole, and the widening section) must use the full-section formwork trolley and pumping operation.

C. The distance between the working surface of the second lining and the bottom working surface shall not be less than 100m, and the distance from the working surface of the short side wall shall not be less than 60m to ensure the normal construction progress of the second lining.

D. The secondary lining construction of the composite lining structure should be selected under the guidance of monitoring and measurement data.

(7) Construction process of short side wall

Steel stencils must be used for the exposed surfaces of the trench walls on both sides of the cast-in-place tunnel.

The elevation of the top surface of the short side wall is determined according to the bottom elevation of the side mould of the trolley; during construction, the joint reinforcement or vermiculite is pre-buried according to the specification, and the contact surface with the secondary concrete is chiseled, and the settlement joint is set at the change of the surrounding rock; The surface of the crucible is wetted with water before pouring to remove debris.

Note that the longitudinal permeable blind pipe and its connection pipe with the grit well are arranged according to the design, and the ring-shaped flexible permeable blind pipe and the waterproof plate joint are reserved, and the embedded parts and the reserved cavern are set.

(8) Trolley assembly and debugging

The lining trolley factory is manufactured and assembled on site. Thoroughly polish the surface of the stencil before lining to remove rust and oil and rust.

(9) Trolley adjustment

The positioning of the trolley template adopts the five-point positioning method, that is, the plane coordinate system is established with the center of the lining as the origin, and the console is controlled by controlling the center point of the top mold, the hinge point of the top mold and the side mold, and the foot point of the side mold. Bit. The curve tunnel should take into account the change of the length of the left and right side overlap caused by the difference between the inner and outer arcs, so that the arc is rounded and the seam is staggered. Pay special attention to the accuracy of the positioning of the trolley, and avoid the intrusion of the second lining concrete by the error or deviation of the elevation.

The trolley formwork and the concrete have proper overlap (≥250px, the curved section refers to the outside). After the position is opened, check whether the connection of each node of the trolley is firm, whether there is any displacement of the trolley, whether the template is warped or twisted. Whether the position is accurate and the lining is clean. In order to avoid the trolley floating when pouring the wall, it is necessary to add wooden supports or jacks on the top of the trolley. Also check if the working window is in good condition.

(10) Reserved caverns and fixed parts

Reinforced concrete lining section, reserved, embedded parts are fixed on the steel frame.

The non-ribbed lining section is drilled on the lining trolley formwork, and the reserved and embedded parts are fixed by bolts.

(11) Install the head plate and rubber water stop or water stop

Head plate mounting

The stop head template of the end of the trolley should ensure the thickness of the design lining and can be adjusted to suit its irregularity. The structure of the stop head should ensure the joint of the lining ring to ensure the quality of the joint and enhance its water stoppage. Features. A small observation window is left at the top to observe the condition of the covered concrete.

Water stop installation

The waterstop is standing at the lining settlement joint, construction joint or expansion joint. Generally, the medium-buried rubber waterstop is used, and the on-site segmentation installation is fixed on the head plate, and the joint can be hot-contacted or cold-connected according to the site conditions.

Water stop installation

The rubber water stop strip is set at the construction joint, and the water stop strip is installed in the groove reserved for the end surface of the crucible. The installation procedure is: cleaning the surface of the crucible – → coating the neoprene binder – → pasting the water stop strip – → Nail fixation – → infusion of new sputum.

(12) Concrete pouring

A. Review whether the trolley form and the center height meet the requirements, and whether the size in the warehouse meets the requirements;

B. Whether the positioning of the trolley and the stop die is secure;

C. Whether the waterstop and waterstop installation meet the design and specification requirements; the waterstop installation: due to the limited function of the waterstop and the service life, it is now generally changed to P201 waterstop;

D. Whether the template joint is tightly packed;

E. Whether the release agent is evenly applied;

F. Whether the cleaning of the basement is clean and whether the construction joint is treated;

G. Whether the position of the embedded part meets the requirements;

H. Whether the transfer pump joint is sealed and the mechanical operation is normal;

J. Is the distribution of the pipeline reasonable and the joints reliable.

The concrete pouring adopts the pumping and pouring process, and the mechanical vibration is compact:

A. Before the pumping, use the cement slurry mixed according to the design mix ratio or the concrete lubrication pipe prepared by halving the aggregate.

B. Layered from bottom to top, alternating left and right, and symmetrically perfused. The height, order and direction of each layer are determined according to factors such as mixing capacity, transportation distance, filling speed, temperature inside the cave and vibration. In order to prevent the displacement of the trolley caused by excessive pressure deviation on both sides during pouring, the height difference of the perfusion surface on both sides should be controlled within 1250px, and the casting speed should be controlled reasonably.

C. The end of the conveying pipe is connected with the hose to control the vertical distance between the nozzle and the casting surface. The surface of the waterproof plate should not be directly flowed to the pouring position. The vertical distance should be controlled within 1.5m to prevent segregation.

D. During the construction process, the pump should be continuously operated and pumped continuously for construction. It should avoid the “cold seam” caused by the stoppage. When the intermittent time exceeds the specification requirements, it should be treated according to the construction joint.

E. When pouring to 1250px under the working window, before the working window is closed, clean the residue and other materials in the vicinity of the window, apply the release agent, and close it to prevent the unevenness of the surface of the window. Leakage phenomenon.

F. The anti-arc part below the arch line of the tunnel lining is the difficult part of the pouring operation, and the effective performance, slump and tamping method are effectively controlled to reduce the bubble in the reverse arc and effectively improve the surface quality of the lining.

G. The top cover is connected to the conveying pipe by the top mold center top sealer, and the top cover is gradually pressed. When the observation hole on the stop plate has a slurry overflow, the mark is completed.

(13) demoulding

According to the construction specification, the strength achieved by the last plate capping test piece is used to control. When the external load is not tolerated, the strength of the concrete reaches 5 (2.5) MPa or the surface and edges of the concrete are not damaged when the mold is removed and the mold can be subjected to its own weight. The demoulding sequence is generally first removed, and the first is removed. First, remove the non-bearing part, and then remove the load-bearing part. The major and complicated formwork has a demoulding plan; when it is guaranteed that the lining is applied in advance and is subjected to surrounding rock pressure, it shall be carried out according to the specifications.

(14) Health

Before the mold is removed, the outer surface of the formwork is washed with water. After the mold is removed, the surface of the concrete is sprayed with high-pressure water to reduce the heat of hydration. The number of surface watering should be such that the concrete surface has sufficient wet state. The maintenance period is not less than 14 days.

(15) Defect processing

After the mold is removed, if defects are found, they shall not be repaired without authorization and may be disposed of after being approved by the supervision engineer.

Bubbles: After mixing with white cement and ordinary cement according to the ratio determined by the color contrast test of the lining surface, partially fill the smoothing.

Ring seam treatment: draw the line with a curved ruler, cut the slit of the cutting machine, the seam depth is about 50px, after partial trimming or grinding with the grinder, it is decorated with high-grade cement mortar and smoothed with a steel file. The construction seam is round and tidy.

Use sandpaper to wipe repeatedly for several times if the surface color is inconsistent.

The surrounding area of ​​the reserved cavern should be cleaned first, then sprayed with water, and the mortar with high marking and uniform color should be used to smooth the calender.