First, the tunnel advanced long pipe shed construction technology

(a), process block diagram

Figure 3.5. 1. 1- 1 Block diagram of pipe shed construction technology

(2), the construction points

(1), the working platform of pipe-shed drilling rig is 6m long, and the concrete-filled steel tube wall is fixed by the front lining grout stop.

(2) Rig installation and pipe shed positioning.

(3) Drilling: using the rotary hydraulic propulsion of the pipe-shed drilling rig to drill to the designed depth.

(4) hole cleaning: after hole formation, use high-pressure water to clean the residue in the hole.

(5) Hole calibration: Pull out the drill pipe and drill bit during measurement, and measure their offset with instruments.

(6) Correction of bending hole: Fill the bending part with mortar, and then drill again after it solidifies.

(7) Inserting steel pipe: For steel pipe connection, a small-diameter steel pipe can be inserted into a large-diameter steel pipe before welding.

(8), grouting plugging hole.

(9) High-pressure grouting: the stratum is reinforced through grouting holes on the steel pipe wall.

Second, the tunnel leading small duct construction technology (see figure 3.5.2)

Fig. 35.2 Block diagram of small conduit construction technology

Key points of construction:

1, be familiar with the design drawings, understand the geological conditions, prepare the drilling and grouting scheme, organize and train the construction team, and equip with enough construction tools.

2, small catheter construction:

(1), the front end of the small catheter is made into a sharp cone, the tail is welded with Ф 6 hoop, 8mm grouting holes are drilled around the pipe arm, and there is no grouting hole at the tail1m.

(2) Before drilling, according to the center line and elevation, design the measuring hole position and control the drilling direction and extrapolation angle.

(3), after the completion of drilling, use pressure feng shui to clean the drilling.

(4) Cement slurry is used for grouting, and the grouting ratio is determined by field test.

(5) The tail of the leading small duct is welded on the steel arch, and the overlapping length of two rows of small ducts is kept above1m..

(6) During grouting, records shall be filled out one by one.

Three, the tunnel drilling and blasting construction technology (see figure 3.5.3)

Figure 3.5.3 Block diagram of drilling and blasting construction technology

Description of construction technology of drilling and blasting operation

Drilling: Class II and III surrounding rocks are drilled by artificial air gun, and Class IV ~ V surrounding rocks are drilled by three-arm drilling jumbo. According to the requirements of drilling and blasting design, the drilling depth, angle and spacing are determined, and the drilling accuracy strictly meets the requirements of construction specifications.

Charging and networking: Before charging, the rock powder in the hole shall be blown clean, and then it shall be carried out in sections from top to bottom. Millisecond detonator, millisecond detonator and second detonator are used for initiation, and accurate initiation is carried out according to the number of pre-designed charge holes. Mixed loading is prohibited, so as not to affect the blasting effect and cause misfire.

Network connection: Connect the network after all unnecessary tools and equipment are evacuated from the blasting face. Connect as close as possible to the eye hole, and the network outside the hole should be as short as possible. The connection should be neat for visual inspection of the network. In order to ensure the reliable initiation of millisecond detonators, the shortest length of detonating tube for initiating detonators must be less than 1.5m, and the whole network is initiated by ordinary lead 8 fire detonators. When using electric power or initiation index, its operation method should be implemented in accordance with the relevant provisions of the national standard "Blasting Safety Regulations".

After the network connection, carefully check whether the connection is correct, whether the primary explosive cartridge in each eye hole is included, and whether there is a primary detonator in each cluster or connecting block. When using hole extension control, it is also necessary to check whether the number of detonator segments at each connection point meets the design.

Inspection of blasting effect: According to the specification requirements, the excavated section after blasting shall meet the requirements in the following table.

Blasting Effect Checklist Table 3.5.3- 1

Serial number requirements, project requirements and contents

1 The allowable overbreak of secondary arch is 10cm on average, and the maximum is15cm; Side wall, inverted arch and bottom of the cave average 10cm.

Class Ⅲ ~ ⅴ arches average 15cm, and the maximum 25cm side walls, inverted arches and cave bottoms average 10cm.

2. Blast hole survival rate: hard rock ≥80%, medium hard rock ≥70%, soft rock ≥50%, and the marks around the blast hole should be evenly distributed on the excavation contour line.

3 The error of the step shape connected by two stubble cleaning guns is not more than 15cm.

Four, the tunnel hollow grouting anchor construction technology (see figure 3.5.4)

Figure 3.5.4 Block diagram of hollow grouting anchor construction technology

Key points of construction

1, mark the anchorage position along the excavation contour of arch according to the design position; Drill holes with air guns to the designed depth, clean the holes with water or high-pressure air, and install anchor rods after inspection.

2. The hollow anchor rod is customized by the manufacturer according to the design requirements. Before use, check whether there is any foreign body blockage in the anchor hole, and clean it up if there is any. Manually install the anchor rod, and the exposed length of the anchor rod shall be kept at 10 ~ 15 cm, and then install the orifice cover (slurry stop).

3. Grouting: the slurry is cement slurry. In order to ensure continuous grouting, grouting pump should be carefully checked before grouting to see whether the conditions are good and whether the accessories are complete; Check whether the pulping raw materials are ready and the quality is qualified.

Grouting sequence: quickly connect anchor rod, grouting pipe and grouting pump with quick connector. Start grouting pump grouting until the slurry overflows around the orifice or the pressure gauge reaches the design pressure value. After the anchorage is completed, the grouting hose and anchorage joint shall be dismantled, cleaned and moved to the next anchorage for use. Slurry should be prepared in strict accordance with the mixture ratio, and it should be used with it, so as to avoid the slurry from condensing in the grouting pipe and the pump. In order to ensure the grouting effect and strictly control the grouting pressure, the rubber grout stopper should be driven into the orifice not less than 30cm. After the gas is exhausted, the holes outside the grout stopper should be immediately blocked with quick-setting cement mortar.

Five, tunnel mortar anchor construction technology (see figure 3.5.5)

Figure 3.5.5 Block diagram of mortar anchor construction technology

Six, tunnel steel support construction technology (see figure 3.5.6)

Seven, tunnel wet shotcrete construction technology (see figure 3.5.7)

Figure 3.5.7 Block diagram of wet sprayed concrete construction technology

Key points of wet shotcrete construction:

The cement is 1, 425# ordinary portland cement, and the sand is machine-made sand. The gravel particle size is controlled at 5- 10mm, and mining is carried out.

Use a liquid accelerator. Before the formal injection, the actual test is carried out to determine the actual initial setting and final setting time, make the specimen, test the strength of the specimen, select the best mixture ratio and verify the operation process.

2. Key points of operation

(1), spray several times according to the thickness, the initial spray thickness is 3 ~ 5 cm, seal the rock surface and make the spray surface smooth; Φ 6 steel bar heads should be buried during layered spraying to check whether the sprayed layer is flat or not. If there is leakage, it should be repainted.

(2) Before spraying, clean the rock surface with high-pressure water or high-pressure wind, and the nozzle is about 1m away from the rock surface. Fix the nozzle on the manipulator for operation. Shotcrete should be perpendicular to the rock surface, move back and forth in a spiral shape from bottom to top along the side, and press for half a circle.

⑤ After the final set of sprayed concrete is 2h, it should be cured by spraying water, and the curing time is generally not less than 7d.

Eight, tunnel waterproof layer construction technology (see figure 3.5.8)

Figure 3.5.8 Block diagram of waterproof layer construction technology

Nine, tunnel lining concrete construction technology (see figure 3.5.9)

Fig. 3.5.9 Process Flow Chart of Secondary Lining of Tunnel

Ten, tunnel pavement engineering construction technology (see figure 3.5. 10)

Fig. 3.5. Block diagram of10 pavement construction technology

Description of construction technology:

1, pavement cushion construction

2, concrete surface construction

(1), before the construction of concrete pavement, the incoming materials shall be inspected, and the inspection items and inspection frequency shall comply with the relevant test regulations.

(2) Before construction, mechanical equipment, measuring instruments, datum lines or templates and various test instruments must be thoroughly inspected and debugged. Vulnerable parts of main construction machinery should be reserved appropriately.

(3) Before the concrete surface is poured, the aggradation and sundries on the surface of the base shall be removed.

(4) The mixing and transportation of concrete shall comply with the relevant provisions in Chapters 5 and 6 of Technical Specification for Construction of Highway Cement Concrete Pavement (JTGF30-2003).

(5) The formwork for pavement construction shall be made of channel steel, and the accuracy and size requirements of the formwork shall comply with the provisions in Section 7.3. 1 of Technical Specification for Highway Cement Concrete Pavement Construction (JTGF30-2003).

(6) The concrete panel is paved with a concrete paver, and its technological process is constructed in the order specified in Technical Specification for Construction of Highway Cement Concrete Pavement (JTGF30-2003).

(7) In order to improve the compactness and early strength of concrete and improve the physical and mechanical properties, the pavement concrete adopts vacuum water absorption technology.

3. Construction of longitudinal joints, transverse contraction joints and expansion joints

(1), longitudinal joints, transverse contraction joints and expansion joints shall be carried out according to the requirements of drawings and the relevant provisions of Technical Specification for Construction of Highway Cement Concrete Pavement (JTGF30-2003).

(2) After the expiration of concrete curing, joint filling shall be done in time according to the requirements of drawings. Before caulking, the joint must be kept dry and clean to prevent sand and other sundries from falling into the joint.

(3) The filling joint should be close to the concrete joint wall, and its pouring depth should be twice the joint width. When the depth is greater than 30 ~ 40 mm, it can be filled with porous flexible substrate. In summer, the joint sealant should be poured to be flush with the board surface; In winter, it should be slightly at the bottom of the board.

(4) Before opening the traffic, the joint sealant should have enough time to harden.

4. Maintenance should be started immediately after concrete pavement paving or soft anti-sliding structure is completed. The spraying of curing agent and covering layer shall comply with the relevant provisions in Section 9.3 of Technical Specification for Construction of Highway Cement Concrete Pavement (JTGF30-2003).

XI。 Tunnel curtain grouting construction technology (see figure 3.5. 1 1- 1)

Fig. 3.5. 1 1- 1 process flow chart of drilling and grouting operation

Key operation points:

1. Installation of opening and orifice pipe: the opening should be slightly pressurized, slowly and provide enough water. For the embedding of orifice pipes, dry early strength mortar shall be used to block and locate them in the waterless area. For the water gushing area at the orifice, the pipe at the orifice is buried with a solid pipe mixture made of reinforced waterproof agent and cement to locate and fix the pipe. See Figure 3.5. 1 1-2 for details. After the orifice pipe is fixed in the pressure water for a certain period of time, it can be drilled or grouted.

Fig. 3.5. 1 1-2 orifice pipe schematic diagram

2. The hole bottom deviation of drilling should not be greater than 1/40 of the hole depth. During drilling, drilling records should be kept strictly: number of holes, footage, development of rock cracks, location of water gushing, water gushing amount and water gushing pressure, etc.

Pre-grouting methods mainly include direct grouting step by step from the working face; Reverse perfusion method from inside to outside; Comprehensive perfusion method; Whole hole one-time perfusion method; Small diameter borehole orifice closed grouting method, etc. Considering that the curtain grouting section is mainly located in the fault fracture zone, the sequence of drilling and grouting is from the outer ring to the inner ring, from near to far, and the holes in the same ring are constructed at intervals. When the rock fracture is easy to cause hole collapse, forward grouting is adopted, otherwise reverse grouting is adopted. For the connection of grouting pipes and the arrangement of grouting system, see schematic diagram 3.5. 1 1-3. Water pressure test should be conducted before grouting, and grouting should be carried out according to specifications after flushing rock cracks as required.

Fig. 3.5. 1 1-3 Schematic Diagram of Grouting System Layout

Grouting procedure is as follows:

Table 6 Project Productivity and Duration Table * * Contract Section

The average number of units (-people, all kinds of machinery-units), average unit productivity (quantity, week), average unit production time (week) and total production units (units) per unit production scale of Project No.

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