| Application of permeating crystallization permanent condensate (DPS) in Tunnel Engineering |
Tunnel diseases and material selection:
1】 Permanent condensate DPS deep penetration integral waterproof: tunnel construction is a high-cost and complex engineering project, and it is also a long-term facility. The ordinary waterproof layer is easy to age and has limited life. Once damaged, it is difficult to repair. Even if it is repaired, the cost is high. The ordinary waterproof layer is also easily damaged during construction. However, the life of DPS is different from that of concrete structure, because it penetrates into concrete with a certain thickness. Therefore, the waterproof performance of the lining block will not be affected as long as there is no wound greater than 10cm deep in the construction process.
2】 Permanent condensate DPS can be constructed on the back water surface: similarly, if the project requires permanent condensate DPS, it can also be constructed on the inner wall of the first lining as the waterproof of the inner lining, or on the inner wall of the inner lining as the anti-corrosion and anti carbonization of the concrete. In the construction of composite lining tunnel, a layer of permanent condensate DPS can also be sprayed directly on the calendered surface of shotcrete as the waterproof reinforcement layer of the inner lining, and both inside and outside can be constructed.
3】 Permanent condensate DPS water absorption hydrophilic crystal waterproof: the tunnel construction is generally underground, and the surrounding geological structure is rich in water. Before the completion of the tunnel, the ventilation of the construction surface is poor, and the air is humid, so the waterproof construction surface is always wet. This requires that the waterproof material can be constructed on a wet basis. The permanent condensate DPS is just a waterproof material that needs wet steam to better penetrate and react. In other words, the permanent condensate DPS can be constructed on the wet surface, which can not be achieved by most other waterproof materials.
4】 The construction of permanent condensate DPS is simple, time-saving and labor-saving. In addition, since the permanent condensate DPS is cold work spraying, the per capita daily workload can reach 1000 square meters or more, and the high construction efficiency is incomparable with other materials, which greatly saves the high labor cost.
5】 DPS is good in acid-base resistance, adhesion and strength: General waterproof materials do not have anti-corrosion performance, but are self waterproof, do not protect the concrete structure, and have no affinity to penetrate into the concrete.
Most of the tunnels in the world are built as urban railway (subway) and road tunnels (railway tunnel and highway tunnel). No matter what purpose the tunnel is used, its construction methods are no more than shield construction method and immersed tube construction method. In view of different construction methods, the following focuses on the shield construction method to describe the application of DPS in waterproof, anti-seepage and anti-corrosion.
1、 Waterproof characteristics of shield construction method
There are many ways to classify the waterproofing of shield tunnel, including single-layer lining waterproofing and double-layer lining waterproofing according to the lining structure; According to the composition of lining, there are lining self waterproofing and lining joint waterproofing; According to the tunnel structure, there are tunnel lining waterproofing and shaft joint waterproofing, and according to the lining material, there are reinforced concrete and cast iron lining waterproofing.
The waterproof of single-layer lining is closely related to the form, composition and assembly of single-layer lining.
The larger the ring width of the lining, the less the circumferential joints of the tunnel in the same mileage, and the smaller the probability of water leakage. Similarly, the less the segments of the lining ring, the smaller the longitudinal joint of the ring, and the smaller the probability of water leakage. Of course, the actual engineering should consider comprehensively the soil layer characteristics, loading conditions, structural characteristics, calculation mode, transportation capacity, fabrication and assembly and other factors of the structure.
（1） Waterproof and manufacturing accuracy of segments and blocks 1. Improve the impermeability of lining segments and blocks: 2. Improve the manufacturing accuracy of initially laid segments and blocks;
3. Add waterproof coating outside the lining to strengthen the impermeability and corrosion resistance of the lining.
（2） Sealing and waterproofing of lining joint surface (joint)
1. The first and main defense line of the lining joint - sealing gasket (water swelling rubber); 2. Sealing and waterproofing of lining screw holes;
3. Caulking groove is filled with sealing waterproof material;
4. The joint surface shall be provided with a groove for injecting sealant, and the sealant shall be injected through the screw hole of the pipe segment to strengthen waterproof or water cultivation.
（3） Back wall (backfill) grouting of shield tunnel
The grouting material with anti mixing function forms a ring-shaped unity on the outer wall of the lining ring, forming a "tunnel waterproof barrier". Although it is mainly used to control land subsidence, it is also the defense line of tunnel waterproofing.
（4） Corrosion protection of lining: corrosion protection of metal lining, metal and concrete composite lining, metal embedded parts in concrete lining and other metals shall also be considered
（5） Double lining waterproof
In addition to the waterproof of the first lining, the waterproof of the inner lining must also be considered.
（6） Waterproofing of shaft and circular tunnel joint
According to the waterproof characteristics of the above shield construction method and combined with the technical characteristics of concrete permanent condensate DPS, the waterproof function outside the lining is mainly described here. |
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