Geosynthetics used in water conservancy projects mainly include geotextiles, geomembranes, geotechnical special materials and geocomposite materials.
Engineering role and application
Reinforcement refers to burying horizontal geosynthetics in a certain part of the soil, also known as reinforced materials. After the soil is compacted, the soil and the reinforced materials are closely combined to form a composite soil (reinforced soil). When a load is applied to the surface of the composite soil, due to the greater friction between the reinforced material and the surrounding soil, the lateral deformation of the soil is limited, which is equivalent to applying a restraining force on the side of the soil.
Thereby improving the bearing capacity of the soil and increasing the stability of the soil. This effect can stabilize and limit the displacement of rock and soil in various structures during long-term use in water conservancy projects, and can transfer or distribute the local stress on the soil to a larger area, increasing the soil The frictional resistance between the body and the geotextile.
Generally, geotextiles, plastic stretched geogrids, warp knitted geogrids, fiberglass geogrids and geonets can be used as reinforcement materials in water conservancy projects. The reinforcement effects of geosynthetics mainly include: the tensile effect of the reinforcement, the interaction between the reinforcement and the soil and the stress diffusion, etc., and in the case of multi-layer reinforcement, the friction effect of the interface between the reinforcement and the soil should be considered separately (ie each layer The effect of the interface between the reinforcement and the soil produces a lateral constraint on the filler) and the interface shear stress generated by the interface between the reinforcement and the soil in the bottom layer creates an additional horizontal constraint on the soil below (improving the stability and bearing capacity of the soil).
Anti-seepage is to prevent fluid from permeating and losing, and it also includes preventing the volatilization and diffusion of gas. In water conservancy projects, a large number of water-retaining and water-retaining, water-diversion, and water-conveying buildings must be constructed, all with requirements for seepage and leakage prevention.
The use of weakly permeable materials in geosynthetics can prevent liquid leakage and gas volatilization to protect the environment or building safety. Geosynthetics used for anti-seepage mainly include geomembrane and composite geomembrane. The latter is more widely used and can adapt to various complex engineering conditions.
Protection refers to the adoption of appropriate protection measures in order to reduce the hazards of natural phenomena, environmental impacts and human activities on the embankment and bank slopes. The development of geosynthetics provides a new way for bank slope protection. Covering a layer of geotextile with good filtering performance on the protected soil surface, and pressing a certain cover weight, can effectively protect the bank slope from water and waves, and can replace traditional slope protection materials.
Geotextiles can separate different soil structures to form a stable interface, separate each layer of structure, and play its own characteristics and overall functions as required to avoid mixing with each other to produce adverse effects. In soil-rock mixed dams, it can be used to isolate different dam materials. The earth-rock dam is built on the rock foundation or pebble foundation with developed cracks, which can be used as the isolation between the dam body and the foundation.
In hydraulic structures, when the water in the soil flows from the fine-grained soil to the coarse-grained soil, or the escape point where water flows from the soil to the outside, an inverted filter layer is required, otherwise the soil particles will be taken out of the soil by the water flow. Excessive soil loss will cause piping and runoff damage. Traditionally, sand and gravel grains are used as filter materials. Generally, sand and gravel with different particle diameters are laid in 2-3 layers, and the construction process is more complicated. The filtering function of the geotextile is exactly the same as the traditional particle layer, which can be replaced in engineering. It can prevent groundwater seepage
Excessive loss of soil particles causes damage, and at the same time allows water to drain smoothly, so as to avoid soil instability due to increased pore water press