Application of Geosynthetics (2) Application in Water Conservancy and Shipping Engineering

Application of Geosynthetics (2) Application in Water Conservancy and Shipping Engineering

In dam and channel seepage prevention, waterway management and flood control and emergency rescue, a large number of geosynthetics have been used, which have played an important and irreplaceable role. The application of geosynthetics in water conservancy and shipping engineering mainly includes the following aspects:

(1) Dam and channel seepage prevention

The construction of dams to store water into reservoirs and the construction of channels for long-distance water transfer all require strict anti-seepage measures, otherwise the benefits for mankind will not be brought into play. Geomembranes are virtually impermeable and are often used on the upstream side of dams to form a hydraulic barrier. In addition to the use of geomembrane for anti-seepage in new dams, sticking geomembrane on the upstream surface is an effective method for the reinforcement of old concrete dams with serious leakage. The geomembrane can be directly exposed, or it can be protected by covering it with, for example, a concrete slab. The exposed geomembrane will have a shortened life due to UV-induced degradation, but it is much easier to repair with an exposed geomembrane than with a covered geomembrane. Covered geomembranes are susceptible to damage, such as being punctured by hard materials. In order to prevent the puncture of the geomembrane, geotextile can be laid as a buffer pad; where the bolts are fixed, a rubber seal is used, as shown in Figure 1-5. Leakage of geomembrane mainly occurs at defective joints and pierced holes. Therefore, strict construction quality control measures must be adopted to reduce construction defects, and construction quality inspections must be carried out to find defects and repair them in time. At present, some small and medium-sized earth-rock dams, construction cofferdams of large-scale reservoirs, and reservoir areas with sand and gravel foundations are also commonly used to prevent seepage with geomembranes.

At present, most of the water channels are lined with concrete to play an anti-seepage role. However, during the use of concrete, it is affected by climatic conditions or aging for a long time, and it is prone to cracks and water leakage. Using GCL or GCL and geomembrane to form a composite lining has better anti-seepage effect and is an ideal choice.

(2) Channel improvement

Waterways are equivalent to highways in traffic engineering, and also require maintenance and governance to ensure smooth flow. But underwater channel remediation is much more difficult than highway maintenance. Geosynthetics play a unique and important role in this regard. For example, geotextiles are used as geoform bags, filled with mortar for bank slope protection; geotextiles are used to sink and drain to prevent waterways from silting or river bed scouring.

Geoform is a large-area, continuous tube bag made of double-layer geotextile (mold bag cloth) connected with nylon ropes at certain intervals. Its function is equivalent to a formwork for concrete construction, filled with mortar or concrete, and used as a river bank slope protection component after forming, as shown in Figure 1-6. This protective member with a certain thickness has strong anti-scour ability, and has been widely used in waterway management and flood-damaged river bank restoration projects in my country, and has achieved good results.

Soft mattress can be made of different materials. Geotextile soft mattress is one of them. It is composed of woven geotextile, polymer mesh rope and weight. It has replaced the traditional firewood mattress for bottom protection, Revetment and waterway improvement. Geotextiles are soft, wear-resistant, and have strong anti-aging ability, and have been used in my country's Yangtze River deep water channel engineering. In the cold regions of Northeast my country, Chinese scientific and technological personnel have creatively developed the technology of sinking on ice. The software sinking has been widely used in protection projects such as Songhua River and Nenjiang River, and has accumulated rich experience and achieved good benefits.

(3) Flood control and emergency rescue

In 1998, a huge flood occurred in the Yangtze River Basin. The successful application of geosynthetics in flood control and emergency rescue has achieved very good social benefits, and has been paid attention to by the country. It has become a turning point for the popularization, application and rapid development of geosynthetics in my country. In the fight against floods, the use of geomembrane tube bags to quickly set up sub-dykes to prevent flood peaks from overflowing the embankment; the use of geotextile bags and geotextiles to seal breaches; the use of geotextile filter pads to prevent the further development of piping, etc., have become important for flood control and rescue. The initiative has made great contributions to the protection of people's lives and property.