Technical indicators of composite geomembrane
1. Technical indicators of composite geomembrane
In order to effectively cut off the external moisture, the barrier adopts an anti-seepage composite geomembrane. During construction, in order to effectively protect the geomembrane and play its role to prevent load damage during construction and subsequent subgrade operations, the structure adopts a composite structure of “two cloths and one membrane”, namely cloth/membrane/cloth structure. The main function of cloth is to protect the membrane, and the membrane is mainly waterproof. The anti-seepage composite geomembrane is used to block the migration of moisture in the frozen soil to the roadbed. For example, it is set on the bottom and sides of the roadbed to form a wrap structure for the roadbed soil or the soil within the freezing depth range, thereby providing a stable soil surrounding.
According to the highway load, the foundation bearing capacity is between 63-66 kPa, and the treatment depth of the low-fill subgrade is 40 cm. In summary, it is recommended that the specific parameters of the composite geomembrane should not be lower than the following standards: the geotextile should be non-woven, the quality of the single-layer fabric should be ≥150 g/m2, the thickness of the intermediate impermeable membrane should be ≥0.3mm, and the total thickness Should be ≥2.4mm, ultimate tensile strength should be ≥17kN/m, the ultimate tensile rate should be ≥ CBR burst strength ≥3.0kN, tear strength ≥0.42kN, vertical permeability coefficient <1×10-11cn
2. Selection of the location of composite geomembrane
There are the frozen soil depth line and the groundwater level line respectively. When the filling height of the subgrade is high, the two lines do not intersect, and the freezing depth of the subgrade is not affected by groundwater. The composite geomembrane can be located near the freezing depth line or on the original ground. When the subgrade is filled with a low-fill embankment, part or all of the subgrade is in the range of frozen soil, groundwater invades the range of the subgrade, the subgrade is seriously affected by seasonally frozen soil, and the composite geomembrane is located near the freezing depth line or below the subgrade.