Application of waterproof technology in highway tunnel construction

A high speed section of a city needs to build a tunnel with two holes and two lanes. The tunnel is divided into left and right line pile numbers, respectively, the length of the left line tunnel is 600m, the pile number is ZK130 + 620, the length of the right line tunnel is 610.6m, and the pile number is YZ130 + 643. The type of highway tunnel constructed belongs to medium length type. During the period, the length of the tunnel is between 38m and 35m, and 9 ~ 20m is the actual depth. The city has a longer summer season, four distinct seasons, with an average annual rainfall of 900 to 1000mm. The main features of groundwater in this project are structural fissure water and Quaternary pore water, the water quality of the actual surrounding rock will be uneven with the change of atmospheric precipitation, road tunnels during the excavation construction will be rain and drip leakage situation, which requires the construction of the active part of the waterproof work, for which we will elaborate in detail below.

2.1.Preparatory work of waterproof construction

The first is the choice of material. When the highway tunnel project is in the link of waterproof construction project, the waterproof construction material selected is synthetic resin waterproof coiled material, in the process of combining the waterproof plate ECB with the actual distribution point, the thickness and the density value used are 1.8mm and 340g / m2, respectively, and the use of the two in the form of composite to ensure that both longitudinal or horizontal to be consistent. The tear strength and elongation at break of the type of waterproof material used shall be more than 62KN / m and more than 480%, meanwhile, the 16Mpa is the actual tensile strength of the waterproof material. Before you put into use, to determine whether the material has a waterproof characteristic verification method is: Detailed observation of the material under the 0.4Mpa pressure, the emergence of the change, if the material itself in half an hour after the water did not occur any leakage and seepage phenomenon, it means that the material conforms to the waterproof quality standard, and can be used in concrete use. Secondly, the construction site preparation link. In order to facilitate the smooth operation of waterproof construction, it is necessary to do the following aspects of construction preparation: 

First, detailed measurement of highway tunnel cross-section, the section of the repair work carried out, with the help of the work trolley to be finished. The presence of agglomerates on the concrete surface should be effectively treated by means of spraying and chisel removal in a timely manner. Second, some of the bolts and reinforced iron will be exposed at the first time after the preliminary bracing operation of the highway tunnel, during the resection, the construction personnel should be completed by oxygen welding or electrical welding, and then in the cut part of the full coverage of the first use of fine stone concrete to carefully smear, the purpose of doing so is to avoid the waterproof board is damaged. Third, a thorough review, testing whether the existence of aging waterproof, empty, discoloration and ripple and any quality problems, the vaulted midline and the welding line shall be installed in the edge area of the waterproof plate. The waterproof layer interception work area should be combined with the actual contour line of total length, and ensure that the winding surface shall be symmetrical and tidy for continued use in future construction.

Usually in the road tunnel waterproof construction, drainage pipe installation is the main construction links, and drainage pipe is divided into vertical pipe and ring to the blind tube, the specific construction technology links are as follows: The laying of the drainage pipe shall be carried out on the bottom wall of the highway tunnel project. The bolts shall be embedded in the pipeline after the completion of the drilling, and the blind pipe shall be subsequently fixed with the catch. Ring blind pipe installation process is: according to the design drawings, determine the surface location of shotcrete, and make the necessary marking records, actively adjust the current leakage situation of the tunnel, apply waterproof belt by external paste. When installing and fixing the water stop, it is necessary to confirm in detail whether it belongs to the embedded type, then in the grouting pipe, the exhaust pipe and grouting pipe are combined as the grouting catheter to be installed, laying grouting pipes should be carried out along the direction of the waterstops, and 550 m is set as the distance between the pipes. The steel bar is used to weld the water stop belt in the construction joint, and the optimum distance between 4500 and 5200cm is the vertical connection. The galvanized sheet water stop with a length of 0.4cm, 7cm to 9cm in thickness is located at the middle of the construction joint, and the intumescent sealgate can be applied to the more difficult location of the waterproof construction.

In the waterproof construction of highway tunnels, in order to effectively combine the distance between the waterproof board and the spray layer,and avoid the concrete due to tightening the phenomenon of deformation, the material selection of waterproof board should be based on relaxation degree. The same density is used to fix the position of the side wall and the waterproof plate arch, and the actual laying process of the waterproofing board of the reserved chamber is completed according to the overall shape of the cavern. At the same time, the bubble and fold can not appear in the laying of waterproof board, and welding firmly waterproof joint, waterproof board itself length exceeds the lining length of about 0.6 m. In the construction of highway tunnel construction joints, we should pay attention to reserve about 1m distance between the waterproof board and construction joints. (As shown in Figure 1) In this process, should pay special attention to easy to leak, shower waterproof board placement and take the appropriate waterproof measures. 

The following is a specific approach: put the water diversion layer into the waterproof board, carefully clean the debris attached to the plane and concrete spray layer after processing, and then lay the waterproof material. Before the laying of waterproof coiled materials, the units concerned need to strictly check the quality of the base surface.

 

Figure 1 Schematic diagram of waterproof board welding

First of all, the waterproof material JS uniform brush in the wall pipe and drainage position and scientific grasp of the deployment of waterproof material ratio, should be in the drainage and through the wall pipe brushing strictly control the brushing thickness, roughly between 0.1 to 0.3 cm. To carry out the overall brushing construction, should be carried out within the scope of 25cm pipeline, and the brushing process should be uniform, secondly, the sealing colloid is evenly smeared on the two sides of the drainage pipe and the pipe, and the thickness of the sealing colloid used in the waterproof construction of the through wall pipeline should be less than 6cm. At the same time, the colloidal heating time should be strictly controlled, in order to prevent the fire caused by excessive heat.

The gap is called deformation joint and designed on account of the uneven settlement caused by the stress degree of different structures. At present, the most important part of the waterproof construction of the highway tunnel project is the waterproof treatment of the deformation joint, for the construction of waterproof , the embedded waterstop is chosen to operate, and the asphalt wood board is used as the filling material of the gap. In the implementation of specific waterproof construction, we can use the embedded grouting steel edge waterstop, the advantage of this water stop belt during use is that the concrete can form the bite under the action of the embedded steel edge. The use of epoxy grouting in the highway tunnel engineering structure for any leakage and leakage situation, to timely grouting, thus to promote the highway tunnel engineering structural deformation of the overall increase in waterproof quality. Monofilament grouting pipe structures suffer a certain degree of damage in the grouting period, setting 3.5 to 5.5 cm for the actual distance between the grouting pipe, and actively set up foam cup in carrying out the specific construction of grouting pipe protection.

In short, waterproof engineering is the weakest link in the construction of highway tunnel project, and the construction quality of waterproofing works directly affects the service life of the tunnel and the safety of the vehicle. Therefore, before the tunnel waterproof construction is carried out, the construction party needs detailed investigation and treatment of the actual situation of the groundwater in the construction site, do a good job in each construction link above waterproof treatment, to ensure the quality of waterproof construction can meet the specified standards, for the safe and smooth operation of the vehicle to provide the best protection.

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