Grouting and water plugging project of Baishudi Tunnel of the special railway line of Shanxi Tiandi Wangpo Coal Mining Co., Ltd.
1. Introduction
The tunnel is located in the rock-soil combined mountain. Due to the settlement of the underlying goaf, a wide range of cracks appear in the concrete lining of the tunnel, accompanied by water drenching, which seriously corrodes the railway tracks in the tunnel. Especially in winter, the water drenching and freezing adhere to the railway track surface, which has seriously affected the normal operation of the special railway line and brought potential safety hazards to the train operation in the tunnel.
Figure1 Cracks in the tunnel
Figure 2 Water drenching point in the tunnel
2. Treatment solution
Grouting with chemical grout (acrylate, water-soluble polyurethane, epoxy resin, caulk compound, etc.) was adopted and carried out by installing a water stop needle on the crack. For grouting works, two-sequence hole grouting scheme was adopted, where the sequence-I hole was a shallow hole, water-soluble polyurethane was injected, and the crack surface was blocked to form a cavity inside the crack; the sequence-II hole was a deep hole, and epoxy resin was injected to plug the deep part of the crack.
Figure 3 Deep profile of sequence-I and sequence-II boreholes | Figure 4 Layout plan of sequence-I and sequence-II boreholes |
3. Construction situation
In this project, grouting and water plugging works were mainly carried out for the part with serious water leakage in the tunnel, and the water plugging operation of the 192m long tunnel was completed. Among them, 1555.13m of cracks (construction joints) and 432m of deformation joints (expansion joints) were repaired and blocked. Refer to Figure 5, Figure 6 and Figure 7 for construction process.
Figure 5 Construction photo 1 Figure 6 Construction photo 2
Figure 7 Construction photo 3
4. Achieved accomplishment
After treatment, there is no water drenching or leakage in the treated area. There is no freezing on the inner wall in winter, which saves the cost of de-icing in winter, slows down the frequency of rail replacement, reduces the cost of railway maintenance, and removes potential safety hazards for railway train operation for the owner.
Figure 8 Inner lining on the north side of the tunnel after treatment | Figure 9 Inner lining on the south side of the tunnel after treatment |
Figure 10 Tunnelafter Treatment
5. FAQ
(1) Why chemical grout is used for tunnel plugging?
A: 1. Chemical slurry grouting has a high efficiency and a good effect on degree of cracking; 2. The construction equipment is light and has little influence on railway operation.
(2) How to choose the position and angle of grouting boreholes?
A: The larger the included angle between the grout incident direction and the fracture surface, the more obvious the grout outflow effect is. The best effect is to design the boreholes directly above the fracture with the grout incident angle parallel to the fracture surface.
(3) How to check the filling effect of slurry?
A: In the process of grouting, the grouting and filling standard is slurry outflow from adjacent grouting holes. At this time, stop grouting in this hole. After grouting in an area (10 ~ 15m) is completed for 5 days, carry out water pressure test on the grouting points with serious water leakage in the original tunnel in this area. If the water pressure does not decrease, the grouting effect is good.
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