Waterproof and drainage construction technology of expressway tunnel?

What is the waterproof and drainage construction technology of expressway tunnel? How was it installed? Please read the article edited by Zhong Da Consulting Company.

According to the construction experience, to do a good job of tunnel waterproof and drainage, we must start from every working procedure in the tunnel construction process. The construction quality of each working procedure, such as pre-grouting, initial support, waterproof board laying, secondary waterproof lining and drainage facilities, has great influence on the waterproof and drainage effect of the tunnel. Waterproof and drainage engineering of highway tunnel plays an important role in the normal operation and safety of tunnel. This paper introduces the waterproof and drainage construction technology of * * highway tunnel, and analyzes and discusses some key points.

I. Overview of the Project

* * The expressway * * tunnel is a two-lane tunnel, with the left line length 1070m and the main line length 1030m. Located in * * Town, Benxi Manchu Autonomous County, Liaoning Province, located in the mountainous area of Liaodong. It belongs to hilly area, with steep mountains and well-developed vegetation. The annual precipitation is 865 ~ 1203 mm, and the groundwater is mainly replenished by atmospheric precipitation. The main address is phyllite in the third member of Gaixian Formation of Liaohe Group in Lower Proterozoic, and the caves are all designed below the groundwater level. In the process of tunnel excavation, water dripping or seepage will occur in fault zones and joints, and a small amount of water will gush in local areas.

Second, the tunnel waterproof and drainage construction points

In order to do a good job in waterproof and drainage engineering of * * tunnel, we are familiar with the design drawings and fully understand the design intention and purpose of waterproof and drainage. According to the design idea of combining dredging and blocking, intercepting and leading drainage, combined with the experience and lessons of previous drainage construction, besides arranging drainage facilities as designed, we also add drainage facilities in places with more groundwater, and at the same time, we carefully make three waterproof barriers according to the design to make water drain out of the tunnel smoothly. In order to overcome the idea of attaching importance to the main body and neglecting waterproofing in previous construction, cadres and workers are regularly educated in ideological quality awareness to improve the quality awareness of all staff. Implement the post responsibility system step by step, conscientiously implement the "three inspections" system, strictly control the process, and eliminate potential quality hazards.

2. 1 The first waterproof and drainage defense line connected by "lead, cut and drain" during initial support.

According to the actual water gushing situation of surrounding rock during excavation, detailed records are made, and corresponding diversion and drainage measures are taken. When the gushing water is concentrated, guide the water with slotted friction anchor before spraying anchor. When the water gushing area is large, a dendritic soft permeable pipe shall be set before the anchor spraying for drainage; when the water gushing is serious, a water collecting hole shall be set for drainage while spraying.

After shotcrete is completed, a water collecting hole for drainage is formed between the excavated rock face and shotcrete, so that the water inrush and leakage of surrounding rock flow to the longitudinal soft permeable pipe at the foot of the wall through drainage devices such as the water collecting hole, and then are discharged into the central drainage ditch of the tunnel through the diversion pipe. The primary support forms permanent groundwater drainage facilities through the guidance of diversion pipeline and the interception of shotcrete. After this treatment, most of the groundwater in the surrounding rock is discharged out of the tunnel through drainage facilities, and there is little water seepage on the concrete surface after shotcreting, which really plays a waterproof role.

2.2 From the very beginning, flexible waterproof and drainage works were set up to form the second line of defense for waterproof and drainage.

2.2. 1 Drainage pipe installation

Before the secondary lining, the broken ends and uneven parts of the anchor rod and steel mesh on the surface of the sprayed concrete in the initial support shall be repaired and sprayed to make the concrete surface smooth and meet the requirements of flexible waterproofing. Then according to the design requirements, 50mm flexible permeable pipes are hung around the arch and side walls. When there is water leakage on the sprayed concrete surface, according to the water leakage, the permeable pipe is used for guidance, or an annular flexible drainage pipe is added and fastened with plastic anchor bolts.

2.2.2 Installation of water tray

Before laying the LDRE flexible drainage board, the quality of the waterproof board should be checked first, and whether the installation of the back drainage pipe meets the design requirements. When installing LDRE drainage board, the position of plastic anchor bolt should be arranged according to the size of waterproof board, and the plastic anchor bolt should be drilled and installed with electric drill. Waterproof board should be hung around the whole with screws and washers, and welded with special plastic welding machine in time to ensure the width of arch joint and weld joint. According to the smoothness of sprayed concrete surface, every two reinforcement points should have a certain margin, so that the sprayed concrete surface of waterproof board can be closely attached when lining. Waterproof board laying construction technology as shown in the figure.

(1) preparation: check the sprayed concrete and the rear drain pipe, and check the quality of the waterproof board.

(2) Welding technology

Answer? The welding temperature should be controlled at 200 ~ 270℃, and the speed should be controlled at 0? 1~0? 15m/ min;

b？ Lap size: the lap size is10cm; ;

c？ Weld width: the weld width is generally 2.5cm；;

d？ Welding operation: when laying waterproof board, the fixing process must be closely coordinated with the welding process. Laying, hanging and fixing should precede welding.

A) Before the start of double-seam welding, the temperature should be tested on a small piece of plastic.

B) If there are any missing or false welds, they should be repaired; If there are burnt, welded and exposed fixing points, they must be covered with plastic sheets.

C) The welded joint shall be smooth and free from bubbles, wrinkles and gaps.

(3) Precautions for waterproof board construction:

Answer? When binding reinforcement, installing formwork and trolley, collision and scraping of waterproof board shall be prevented; Rubber pad must be added to support the water deflector when it contacts with the waterproof board;

b？ When pouring concrete, the waterproof board should be prevented from bumping, and the spacing between the pipes buried in the secondary lining and the waterproof board should be not less than 5cm to prevent the waterproof board from being damaged. When pouring, there should be a special person to observe and repair the damage immediately.

c？ The direction and arrangement distance of installation holes should be strictly controlled to avoid overlapping difficulties during installation.

(4) Handling under special circumstances:

Answer? In the process of pouring concrete, if it is found that the waterproof board is laid too tightly, in order to avoid cracking, the plastic waterproof board can be broken according to the scope, and another waterproof board can be cut at the break to make it close to the rock wall, and then the new and old waterproof boards can be welded into a whole;

b？ In areas with large water leakage or water, tarpaulins, films, plastic sheets and other materials must be used to guide the water away from the construction face. The waterproof board is laid in a suitable position, and then removed, and the water flows down the waterproof board.

2.3 Pouring impervious concrete and burying settlement joints and construction joint waterstops to build a waterproof third line of defense.

For waterproof lining, BR-3 expansion agent is added to the mixed concrete to improve the impermeability of concrete, and simple lining trolley is used for lining formwork to ensure the supply of concrete.

2.3. 1 perfusion method

(1) The grouting work of each group of lining should be started as far away from the concrete pump as possible, which is conducive to continuous operation.

(2) In order to prevent the concrete pipeline from moving after installation, a hose is connected to the pipeline near the pouring face, and a funnel is set in the operation window.

(3) When pouring, the left and right sides should be layered and balanced, and each pouring layer should be compacted with a vibrator.

(4) In order to facilitate the sealing of the arch ring, we reserved five operation windows at the top of the trolley. On each operation window, weld a pipe with concrete when capping and pressurizing. When capping, connect the concrete nozzle with the concrete delivery pipe when pressing the operation window, and directly press the concrete into the top of the arch ring with the delivery pump. When the working pressure of the delivery pump rises to 2 times or even higher than the normal working pressure, stop pressurizing and close the concrete delivery pipe in the operation window. Then connect the concrete delivery pipe to the next window until all the operation windows are pressed by concrete.

2.3.2 and matters needing attention

(1) Concrete mixing shall be calculated in strict accordance with the mixture ratio.

(2) The concrete lining is operated by the delivery pump. Therefore, the maximum material diameter of coarse aggregate should be below 30mm, the water cement ratio should be 0.5 1, and the slump should be controlled at 7 ~ 10 cm.

(3) Waterproof concrete construction, each group should be finished as soon as possible.

(4) When the self-falling height of concrete exceeds 1.5m, the concrete shall be transported in tandem.

(5) The reserved construction joints should be slotted and installed with water stops. In order to make the joint closely combined, before pouring, the surface of the joint should be chiseled, the sundries should be cleaned, rinsed with water and kept moist, and then paved with cement mortar with a thickness of 20 ~ 55 mm in the same proportion.

(6) Waterproof concrete must be vibrated and compacted, and the insertion distance of internal vibrator shall not exceed 1 of its effective radius. 5 times, avoid under vibration, leakage vibration and over vibration, pay special attention to the vibrating compaction of construction joints and embedded parts, and prevent the vibrator from touching the formwork, water stop and embedded parts.

2.4 completes the drainage facilities, ensure smooth drainage.

According to the design requirements, horizontal drainage pipes shall be buried, and central insulation ditches and side ditches shall be installed to ensure the design slope and joint compactness.

Key points of construction:

2.4. 1 When installing prefabricated components such as central thermal insulation ditch and side ditch, the joints of prefabricated components shall be filled with asphalt flax, and two pieces of felt coated with hot asphalt shall be wrapped to prevent water leakage and ensure the design slope of smooth running water.

2.4.2 The upper half of the buried centrifugal flower tube is covered with plum blossom holes, covered with non-woven fabric and filled with slag.

2.4.3 The outlet of the central drainage pipe shall be insulated according to the design requirements.

Third, the conclusion

According to the construction experience, to do a good job of tunnel waterproof and drainage, we must start from every working procedure in the tunnel construction process. The construction quality of each process, such as pre-grouting with leading small pipes, initial support, waterproof board laying, secondary waterproof lining and drainage facilities, has a great influence on the waterproof and drainage effect of the tunnel, and a slight negligence in construction may cause hidden dangers of water leakage. Therefore, the construction quality of each process must reach the expected effect of design, so as to ensure the quality of tunnel waterproof and drainage engineering.

The above are collected and sorted by Zhong Da Consulting Company.

For more information about project/service/procurement bidding, and to improve the winning rate, please click on the bottom of official website Customer Service for free consultation:/#/? source=bdzd