CN206736963U - Ditch millet section high water level district lid tunnel stagnant water structure - Google Patents

Abstract

A waterproof structure for a covered tunnel in a high water level area in a valley section includes a cement-soil mixing pile wall under the foot of a cover arch, a cement slurry waterproof curtain under the bottom of the tunnel, and a waterproof device for the top of the cover arch. The cement-soil mixing pile wall, the cement slurry waterproof curtain under the bottom of the tunnel, and the waterproof device for the top of the cover arch together form a complete waterproof structure to reduce the risk of groundwater during the construction of a covered tunnel in a high water level area in the valley section, and can also enhance the bearing capacity of the foundation at the foot of the cover arch and improve the engineering properties of the tunnel surrounding rock.

Description

A water-stop structure for cover-excavated tunnels in high-water-level areas of valley sections

technical field

The utility model relates to a cover-excavation tunnel water-stop structure in a high water level area of a valley section, belonging to the technical field of tunnel engineering waterproof construction.

Background technique

With the rapid development of basic transportation facilities in western my country, a large number of tunnel projects have sprung up everywhere. In the western region of our country, there are many mountains and ridges, and there will inevitably be a large number of tunnels passing through the valley sections of the mountains, which will inevitably form ultra-shallow tunnels in the valley sections, and the cover-excavation method can ensure the safety of construction support in the ultra-shallow sections. Reduce the impact on the surrounding environment and restore ground traffic in a short period of time. The cover-and-excavation construction method has advantages that other construction methods do not have in ultra-shallow sections of tunnels. There will be more and more cover-excavation constructions in the construction of ultra-shallow buried tunnels in mountains. But generally speaking, mountain gullies are eroded by rainwater all year round, and the geological environment is generally poor. The surrounding rock of the tunnel has low strength, poor stability, loose and broken rock mass, and is accompanied by a certain degree of surface water seepage, etc. Tunnel collapse often occurs. Even mountain instability and landslides have brought difficulties and risks to the support construction of cover-excavation tunnels and subsequent normal operation and use.

Utility model content

The utility model solves the deficiencies of the prior art and provides a method that can reduce the risks brought by the groundwater in the high water level area of the valley section during the construction of the tunnel cover and excavation, and avoid the large deformation and instability of the tunnel due to the action of the groundwater. Cover and dig tunnel water-stop structures in the water level area.

The utility model proposes a cover-dug tunnel water-stop structure in the high water level area of the valley section, at least one row of cement-soil mixing pile walls vertically arranged on both sides of the tunnel, the bottom of the cement-soil mixing pile wall is in the soil The depth of the cement-soil mixing pile wall is greater than the depth of the bottom of the tunnel. The cement-soil mixing pile wall extends along the extension direction of the tunnel to cover both sides of the entire tunnel cover excavation area. The water stop piece of the mixing pile wall is used as a connecting piece to connect the cover arch between two cement-soil mixing pile walls. Prevent water from seeping into the tunnel from both sides of the tunnel through the cement-soil mixing pile wall, and prevent water from flowing into the tunnel from the bottom of the cover arch along the gap between the cover arch and the cement-soil mixing pile wall through the water stop connected to the cover arch. It effectively controls the water seepage in the tunnel during the construction of the cover-excavation tunnel, and at the same time improves the stability of the cover arch. Through the vertically arranged cement-soil mixing pile wall, the stability of the cover arch is greatly improved, and the slope body in the valley section can also be improved. The stability of the tunnel can reduce construction disasters, improve the engineering properties of the tunnel surrounding rock, strengthen the integrity of the broken surrounding rock in the valley section, save the engineering cost, and reduce the difficulties and risks caused by groundwater to cover and excavate the tunnel construction.

The soil below the tunnel is also provided with a cement slurry water-stop curtain formed by grouting and arranged in the horizontal direction. Below, the cement slurry water-stop curtain is arranged between two cement-soil mixing pile walls and connected with the two cement-soil mixing pile walls respectively. The cement slurry water-stop curtain installed on the bottom of the tunnel prevents the water outside the cement-soil mixing pile wall from pouring back into the tunnel from the bottom of the cement-soil mixing pile wall, so as to better control the phenomenon of water gushing in the tunnel during tunnel construction.

Preferably, the cement slurry water-stop curtain is divided into two sections and arranged close to the cement-soil mixing pile walls on both sides.

Preferably, the cement-soil mixing pile wall is provided with multiple rows of cement-soil mixing piles, and the distance between each adjacent row of cement-soil mixing piles is 500mm.

Preferably, the water stopper is a waterproof board, the waterproof board is arranged along the centerline of the cement-soil mixing pile wall, the gap between the waterproof board and the cement-soil mixing pile wall is sealed by asphalt, and the waterproof board exposes the cement-soil The part of the mixing pile wall is integrated with the arch foot of the covered arch.

Preferably, the cement-soil mixing pile wall is composed of a plurality of cement-soil mixing piles vertically arranged along the extension direction of the tunnel, and the adjacent cement-soil mixing piles overlap each other.

Preferably, the diameter of the cement-soil mixing pile is 600 mm, and the overlapping width of adjacent cement-soil mixing piles is 100 mm.

Preferably, a waterproof layer is laid on the vault of the cover arch, and then a cement anti-seepage layer is laid after the backfilling is completed, and the cement anti-seepage layer is connected to the intercepting ditch at the foot of the slope.

To sum up, the utility model has reasonable design and convenient construction. It can effectively control the water seepage in the tunnel and the water gushing at the bottom of the tunnel during the construction of the cover-excavation tunnel. Stability, reducing construction disasters, improving the engineering properties of the tunnel surrounding rock, strengthening the integrity of the broken surrounding rock in the valley section, saving engineering costs, and reducing the difficulties and risks brought about by groundwater during tunnel construction.

Description of drawings

Fig. 1 is a schematic diagram of the structure of the utility model arranged around the tunnel.

Fig. 2 is the structural representation of the cement-soil mixing pile wall of the utility model.

Fig. 3 is a schematic diagram of the structure after the top of the cement-soil mixing pile wall is connected with the waterproof board.

In the attached drawings: 1. Cement-soil mixing pile, 2. Waterproof board, 3. Cover arch, 4. Sand and gravel cushion, 5. Grouting pipe, 6. Cement slurry water-stop curtain, 7. Secondary lining, 8. Clay Anti-seepage layer, 9. Backfill soil, 10. Intercepting ditch, 11. Waterproof layer.

detailed description

The technical scheme of the utility model is described in further detail below by means of the accompanying drawings.

Example,

A cover-excavated tunnel water-stop structure in a high water level area of a valley section, comprising a cement-soil mixing pile wall at the foot of a cover arch, a cement slurry water-stop curtain under the tunnel bottom surface, and a cover-arch vault top waterproof device. The cement-soil mixing pile wall is formed by overlapping single-axis cement-soil mixing piles, which are driven into the soil to form a water-stop curtain. After the cement-soil mixing pile wall is completed, a 20cm deep groove is opened at the top of the pile to cross the center of the circle. Place the pre-welded waterproof board 2 with a height of 50cm, and then use asphalt to seal the joints, and finally expose a section of the waterproof board and the arch foot of the arch 3 as a whole, which can prevent water from flowing from the joint between the arch and the mixing pile wall infiltration; the cement slurry water-stop curtain 6 is after excavating the inner contour of the tunnel, using a small drilling rig to drill holes at the arch foot of the tunnel, inserting the wall casing while drilling, and putting the grouting pipe until the predetermined grouting depth, Use the cement slurry pump to pour the cement slurry and fly ash mixed in a certain proportion, and add early strength agent to increase the early strength to form a cement slurry water-stop curtain connecting the cement-soil mixing pile wall. The waterproof device for the roof of the arch 3 is to lay a waterproof layer 11 on the arch after the strength of the arch reaches the design value, and then start backfilling the top of the cave. An intercepting ditch 10 is provided at the joint between the seepage layer 8 and the cement anti-seepage layer 8 and the slope toe. The cement-soil mixing pile wall, the cement slurry water-stop curtain under the tunnel bottom and the waterproof device of the arch vault form a complete water-stop structure to reduce the risk of groundwater during tunnel construction in water-rich areas and strengthen the arch The bearing capacity of the foundation of the arch bottom can be improved, and the engineering properties of the surrounding rock of the tunnel can be improved. The elevation of the combined water-stop structure can be seen in Figure 1.

The specific construction steps are as follows:

As shown in Figures 1 to 3, cement-soil mixing pile walls are installed at the arch feet on both sides of the cover arch 3. Specifically, a plurality of cement-soil mixing piles 1 with a diameter of 600mm are continuously arranged at the arch feet along the extension direction of the tunnel to form cement For the soil mixing pile wall, adjacent cement-soil mixing piles 1 are overlapped with each other, and the overlap width is 100mm. In this example, two rows of cement-soil mixing piles are arranged on each side of the cement-soil mixing pile wall, and the pile center between each row of cement-soil mixing piles The distance is 500mm. In this example, the cement content of the cement-soil mixing pile is 16%, plus an early strength agent to improve the quality of the pile, the speed of the stirring shaft is 60rad/min, and the water-cement ratio is controlled at 0.5:1. During the construction process, pay attention to stirring evenly , The lifting speed and the spraying speed should be coordinated to ensure uniform spraying along the entire length of the pile body. See attached drawings 2 and 3 for the plane layout and elevation of the cement-soil mixing pile.

Concrete construction steps of cement-soil mixing pile wall:

(1) Measure the release point. Use theodolite to measure the borderline and pile position of the area; clearly mark and number the calibrated reference point and pile position, and do a good job of protection; make a record of the measurement and setting out for review.

(2) The pile driver is in place. Before the pile driver is in place and moving, see the upper, lower, left and right sides clearly, find any obstructions and eliminate them in time, check the positioning situation after the movement, and correct it in time; use a spirit level to correct the base and keep the base level, Ensure that the pile driver is stable and upright; the center of the three points of the power head, the mixing head and the pile position are located on the same vertical line; the positioning deviation of the pile position is not more than 40mm, and the verticality deviation of the pile body is less than 20mm.

(3) Pre-stir and sink. Strictly control the sinking speed, and closely observe the working load of the motor of the power head. The current index is not greater than 70A to prevent the motor from being burned; Wet soil will accelerate the sinking; strictly control the pile bottom elevation, the mixing head must sink to the design pile bottom elevation.

(4) Mortar preparation. While the mixing head is pre-stirring and sinking, make mortar strictly according to the design mix ratio. The water-cement ratio should be strictly in accordance with the design requirements of 0.5:1, and the mortar mixing time should not be less than 2 minutes to fully mix the slurry; The ratio is dissolved in water, and then quantitatively added to the mixing slurry and stirred together;

(5) The first grouting is lifted and stirred. After the stirring head reaches the design elevation of the pile bottom, lift it up 20cm immediately and turn on the grouting pump (40L/min) to deliver the slurry. After the stirring head stirs at the bottom of the pile for 20-30 seconds, it will be stirred at a lifting speed of about 0.5m/min. While lifting, until the design pile top elevation, and check the amount of grouting.

(6) The second stirring sinks. After the grouting stirring is raised to the design pile top elevation, the grouting is stopped, and the stirring immediately sinks to the design pile bottom elevation, and the sinking speed is well controlled, generally about 0.5m/min.

(7) The second grouting stirring is lifted. After stirring to the design pile bottom elevation, send the slurry. After the slurry is sent in situ and stirred for 20-30 seconds, the grouting is lifted at a lifting speed of about 0.5m/min. Speed, and in-situ grouting at the top of the pile and stirring for 15 to 30 seconds to ensure the quality of the top of the pile.

(8) Sinking, lifting and stirring for the third time.

(9) After the pile is completed, the drill pipe and pipeline are cleaned, and the pile frame is moved to the next pile position.

After the lapping of the cement-soil mixing pile is completed, a groove with a depth of 20 cm is made on the top of the wall pile of the cement-soil mixing pile, and a 50 cm high waterproof board 2 welded in advance is placed. The cut-off waterproof board and the 3 arch feet of the cover arch are cast-in-place as a whole, which can prevent water from infiltrating from the joint between the cover arch and the mixing pile wall. The plane layout of the cement-soil mixing pile wall and the elevation of a single cement-soil mixing pile are shown in attached drawings 2 and 3.

After the cement-soil mixing pile wall is constructed and maintained for 28 days, a 10cm sandstone cushion 4 is set at the foot of the arch arch. After the cushion layer has been constructed, immediately install the cover arch steel arch, and pour the cover arch. When pouring the cover arch, the waterproof board 2 protruding from the cement-soil mixing pile wall is cast together with the cover arch. After the construction and maintenance of the arch cover reaches the design strength, the construction of the waterproof device for the arch cover arch begins.

The waterproof device of the arch vault is as follows: after the strength of the arch reaches the design value, a waterproof layer 11 is laid on the arch, and then the top of the cave is backfilled. After the backfill is compacted in layers, a 50cm-thick cement is laid to prevent seepage Layer 8, and finally set the intercepting ditch 10 at the connection with the slope toe. Intercepting ditches are used to divert water that runs down the slope during rainfall.

After the construction of the waterproofing device for the vault roof is completed, the tunnel excavation construction starts. After a certain depth of excavation, the construction of the cement slurry water-stop curtain 6 is started at the arch foot of the tunnel. The specific construction process is as follows:

The technological process of the cement slurry water-stop curtain 6 is: drilling → lowering the grouting pipe 5, casing → pulling out the casing while grouting → sealing the hole. Before grouting, relevant technical parameters such as grouting pressure and grouting hole spacing should be determined; the grouting hole spacing should be determined through on-site grouting tests, that is, selected according to conditions such as rock and soil cracks, looseness, permeability, and grouting equipment capabilities. In the high water level area of the valley section, the thickness of the cement slurry water-stop curtain 6 is set to 0.8m; the grouting pressure refers to the total pressure on the grouting section, that is, the pressure indicated on the pressure gauge at the orifice, and the pressure used depends on the borehole It depends on the depth, the permeability of the soil and the consistency of the cement slurry, etc., generally 0.2-0.6Mpa. The grouting hole spacing is determined according to the specific geological conditions and on-site grouting experiments, but it must be ensured that the overlap is reasonable and there are no cracks.

Use a small drilling rig to drill holes at the arch foot of the tunnel, drill to the required depth and detect the geological conditions, drill into the wall casing while drilling, and then insert the grouting pipe in the casing, the lower part of the grouting pipe and the bottom pipe Grouting holes are drilled on the wall, and the gaps on the surface of the tunnel drilling are filled with cement mortar. The cement slurry and fly ash mixed in a certain proportion are poured with a cement slurry pump, and an early strength agent is added to increase the early strength, and then pulled out For the casing, use a grouting pump to press the grout into the grouting pipe and penetrate into the pores of the soil layer. The grout should be pressed in one time continuously without interruption. Grouting starts with thin grout and gradually thickens. The grouting sequence generally sinks the grouting pipe to the entire depth at one time, and proceeds continuously in sections from bottom to top. Pull out the grouting pipe in sections until the design elevation. The grouting should be carried out in intervals. Group 2 and Group 3 until the lapped cement slurry waterstop curtain is formed, and the horizontal length of the cement slurry waterstop curtain 6 on each side is about one-third of the span of the tunnel.

Claims (7)

1. A cover-excavation tunnel water-stop structure in the high water level area of the valley section, is characterized in that: at least one row of cement-soil mixing pile walls vertically arranged is arranged on both sides of the tunnel, and the bottom of the cement-soil mixing pile walls is placed in the soil body The depth in the middle is greater than the depth at the bottom of the tunnel, and the cement-soil mixing pile wall extends along the extension direction of the tunnel to cover both sides of the entire tunnel cover and excavation area, and the contact surface between the cement-soil mixing pile wall and the cover arch is provided with a protruding cement-soil The waterstop of the mixing pile wall, the waterstop is used as a connecting piece to connect the cover arch between two cement-soil mixing pile walls, and the soil below the tunnel is also provided with grouting molding along the A cement slurry water-stop curtain arranged in the horizontal direction. The cement slurry water-stop curtain extends along the extension direction of the tunnel and is installed under the tunnel arch foot in the entire cover-excavation area. The cement slurry water-stop curtain is set on two cement-soil mixing pile walls between them and are respectively connected with two cement-soil mixing pile walls. 2. The water-stop structure of cover-excavated tunnels in the high-water level area of the valley section according to claim 1, characterized in that: the cement slurry water-stop curtain is divided into two sections and arranged close to the cement-soil mixing pile walls on both sides. 3. The cover-dug tunnel water-stop structure in the high water level area of the valley section according to claim 2, characterized in that: the cement-soil mixing pile wall is provided with multiple rows of cement-soil mixing piles, and the piles between adjacent rows of cement-soil mixing piles Heart interval 500mm. 4. The cover-excavation tunnel water-stop structure in the high water level area of the valley section according to claim 3, characterized in that: the water-stop member is a waterproof board, and the waterproof board is arranged along the center line of the cement-soil mixing pile wall, and the waterproof The gap between the board and the cement-soil mixing pile wall is sealed by asphalt, and the part of the waterproof board exposed to the cement-soil mixing pile wall is integrated with the arch foot of the cover arch. 5. The cover-excavation tunnel water-stop structure in the high water level area of the valley section according to any one of claims 1 to 4, characterized in that: the cement-soil mixing pile wall is composed of a plurality of cement-soil mixing piles arranged vertically along the extension direction of the tunnel It is arranged in an arrangement, and the adjacent cement-soil mixing piles are overlapped with each other. 6. The cover-dug tunnel water-stop structure in the high water level area of the valley section according to claim 5, characterized in that: the diameter of the cement-soil mixing pile is 600 mm, and the overlapping width of adjacent cement-soil mixing piles is 100 mm. 7. The cover-excavation tunnel water-stop structure in the high water level area of the valley section according to claim 6, characterized in that: a waterproof layer, backfill soil and cement anti-seepage layer are successively laid on the vault of the cover arch from bottom to top.