What are the construction techniques for anti-seepage and plugging in water conservancy projects?

Recently, with the continuous advancement of water conservancy engineering construction, various water conservancy facilities such as reservoirs, dams, channels, and pump stations play an important role in flood control, irrigation, water supply, power generation, and other aspects. As the core link of hydraulic engineering construction, anti-seepage and leakage prevention are directly related to the safety, stability, service life, and operational efficiency of the project. During the long-term operation or construction process of hydraulic engineering, it is prone to problems such as leakage and piping due to geological conditions, construction techniques, hydrological environment, etc. If scientific anti-seepage and plugging measures are not taken in a timely manner, it may cause engineering hazards and even threaten the safety of surrounding people's lives and property.
The anti-seepage and plugging construction of water conservancy projects follows the core principles of "plugging at the top and draining at the bottom, adapting to local conditions, and treating both symptoms and root causes". Based on the type of project, leakage location, degree of leakage, and geological conditions, appropriate construction techniques are selected to achieve the construction goal of "anti-seepage as the main and plugging as the auxiliary", ensuring that the anti-seepage performance of the project meets the standard and effectively curbing leakage hazards. Industry experts say that anti-seepage construction focuses on early prevention, reducing water infiltration by building a sound anti-seepage system; The construction of leak prevention focuses on post treatment, and precise measures and rapid sealing are taken to address existing leakage problems. The two complement each other and jointly ensure the safe and stable operation of water conservancy projects.

The anti-seepage construction technology is mainly applied in the early stage of water conservancy engineering construction, by constructing anti-seepage barriers to reduce water infiltration from the source. Common techniques include grouting anti-seepage, anti-seepage wall construction, geotechnical material anti-seepage, and clay covering anti-seepage, which are suitable for different geological conditions and engineering sites.

Grouting anti-seepage technology is one of the widely used and mature anti-seepage technologies in hydraulic engineering. It mainly injects grouting materials into the cracks and pores of the foundation or dam body to form a continuous anti-seepage curtain and block the water infiltration channel. According to different grouting materials, it can be divided into cement grouting, clay grouting, chemical grouting, and composite grouting. Cement grouting is suitable for rock and gravel foundations, with a wide range of material sources and moderate costs. Through the solidification and hardening of cement slurry, a strong anti-seepage structure is formed. In the Dashixia Water Conservancy Hub Project in Xinjiang, the construction team used cement grouting technology to penetrate nearly 50 meters of loose sand and gravel layers, construct anti-seepage curtains, and ensure the safety of the dam. Chemical grouting is suitable for complex scenarios such as fine cracks and weak foundations. For example, in the Ba Dashi Reservoir project, the construction team innovatively adopted shallow chemical grouting technology in fault zones, effectively solving the problems of water absorption and easy lifting in highly weathered strata, and improving the anti-seepage performance of the strata. Composite grouting combines the advantages of different grouting materials. For example, the Niya Water Conservancy Hub project adopts the composite technology of "cement grouting+silica sol chemical grouting" to accurately seal micro cracks in the surrounding rock and further improve the anti-seepage performance of the project.

The construction technology of anti-seepage walls is mainly applicable to scenarios such as deep permeable foundations and dam anti-seepage. Continuous anti-seepage walls are poured into the foundation or dam body through specialized equipment to block water infiltration. The commonly used types of anti-seepage walls include concrete anti-seepage walls, interlocking concrete well column anti-seepage walls, mortar sheet pile anti-seepage walls, etc. Among them, concrete anti-seepage walls are suitable for situations with deep permeable layers, and have the characteristics of stable anti-seepage effect and strong bearing capacity. They are widely used in large reservoirs and dam projects. During construction, it is necessary to strictly control the thickness, strength, and pouring quality of the wall to ensure that the wall is continuous without cracks.

Geotechnical anti-seepage technology is a new type of anti-seepage technology that has been widely applied in recent years. It mainly uses polymer materials such as geomembranes and bentonite waterproof blankets, which are laid on the surface or inside of the project to form a flexible anti-seepage layer. Geomembranes have the characteristics of good anti-seepage effect, convenient construction, and strong adaptability, and are suitable for projects such as channels, reservoirs, and dams. When laying, it is necessary to ensure that the base layer is flat and solid, avoid sharp objects piercing the material, and conduct weld seam testing to ensure that the anti-seepage layer is sealed and intact; Bentonite waterproof blanket takes advantage of the swelling characteristics of bentonite when encountering water to form a high-density gel like water resisting layer, which is suitable for anti-seepage of various soft foundations. After laying, it needs to be backfilled in time to prevent material damage. In addition, as a traditional anti-seepage technology, clay blanket anti-seepage is suitable for single-layer foundations with deep impermeable layers. By laying layered and compacted clay layers, a dense anti-seepage barrier is formed, which is low-cost and easy to construct. Some projects still use this technology.

The plugging construction technology mainly focuses on targeted treatment of leakage, piping and other problems that occur during the operation of water conservancy projects. Common techniques include crack plugging, joint plugging, grouting plugging, and drainage filtration plugging. Suitable construction methods should be selected according to the type and severity of leakage.

Crack sealing technology is suitable for crack leakage in dam bodies, tunnels, culverts, and other parts. Different sealing methods are used according to the width and depth of the cracks. For cracks with smaller widths, materials such as epoxy mortar and polymer cement slurry can be used for surface coating and sealing to enhance the anti-seepage ability of the crack; For cracks with large width and deep depth, it is necessary to first clean the debris and floating debris inside the cracks, then embed sealing materials, and inject grouting materials to achieve complete sealing. This method is commonly used to deal with crack leakage in concrete dams and masonry dams. The joint sealing technology is suitable for leakage at the joints of walls and components. By embedding materials such as waterstops and sealants at the joints, the gap between the joints can be filled and the leakage channel can be blocked. For example, if there is leakage at the expansion joints of culvert pipes, backfill asphalt, polyurethane and other materials can be used, combined with rubber waterstops for joint sealing.

Grouting plugging technology is an efficient plugging method for hidden leakage, piping and other problems. It injects plugging slurry into the leaking area through professional equipment, and after the slurry solidifies, it forms a strong plugging body to block water infiltration. Commonly used leak stopping slurries include cement slurry, polyurethane slurry, and acrylic slurry. Among them, polyurethane slurry has the characteristics of water swelling and strong adhesion, and is suitable for various complex leakage scenarios, which can quickly block leakage channels; Cement slurry is suitable for large-scale leakage plugging, with moderate cost and stable plugging effect. In actual construction, the construction team will adjust the slurry concentration and grouting pressure according to the leakage water flow rate and leakage location to ensure the sealing effect and avoid secondary leakage.

The drainage filter plugging technology is suitable for leakage problems such as piping and soil flow. The core is to set up a filter layer to discharge the seepage while preventing the loss of soil particles, thereby containing the hidden danger of leakage. This technology is usually used in conjunction with grouting and plugging. Firstly, the seepage water pressure is reduced through drainage facilities, then an anti filter layer is laid, and finally grouting and plugging are carried out to form a "combined drainage and plugging" treatment system, which is suitable for pipe surge treatment in dams, foundations and other parts. For example, after a small reservoir dam encountered a risk of piping, the construction team used a combination of "sand and gravel filter layer+polyurethane grouting" to first lay multiple layers of sand and gravel filter layer to intercept soil particles, and then inject grouting materials to block the leakage channel, quickly controlling the risk of piping and ensuring the safety of the dam.

The reporter learned that quality control of anti-seepage and plugging construction in water conservancy projects is particularly important. Construction units need to strictly follow industry standards, conduct geological surveys before construction, control construction processes during construction, and conduct post construction effect testing. Before construction, it is necessary to clarify the location, degree, and geological conditions of potential leakage hazards through geological drilling, hydrological monitoring, and other methods, in order to provide a basis for technical selection; During the construction process, it is necessary to strengthen the control of material quality and construction technology, such as the proportion of grouting materials, the pouring accuracy of anti-seepage walls, and the injection pressure of leak proof grout, all of which must meet the design requirements; After the construction is completed, the anti-seepage and plugging effects need to be tested through water injection tests, leakage observations, and other methods to ensure that the design standards are met.

Industry experts remind that anti-seepage and plugging in hydraulic engineering is a systematic project that needs to be combined with practical engineering and flexibly matched with various technologies to avoid the limitations of a single technology application. With the continuous upgrading of construction technology, new types of anti-seepage and plugging materials and processes continue to emerge, such as environmentally friendly chemical grouting materials, intelligent grouting equipment, etc., which not only improve construction efficiency and anti-seepage effect, but also more in line with the concept of green construction. In the future, with the continuous deepening of water conservancy engineering construction, anti-seepage and plugging construction technology will develop towards refinement, intelligence, and green direction, providing stronger guarantees for the safe and stable operation of various water conservancy facilities, and helping water conservancy projects to exert greater ecological and social benefits.