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对于采用土工膜库盘防渗的平原水库,蓄水初期,土工膜缺陷渗漏,极易引起库区土工膜膜下非饱和土层中孔隙气体聚集、上升,并使土工膜产生局部隆起的气胀现象。分析了库水渗漏引起土工膜气胀变形的机理,研制了超大型专用气胀试验设备,利用渗漏区和非渗漏区气胀试验来模拟土工膜缺陷渗漏引起的气胀现象,得出结论:①对于没有缺陷的土工膜,在地下水位不变时,水库蓄水不会产生土工膜气胀现象;②平原水库蓄水初期,土工膜缺陷渗漏,渗水可侵占原膜下砂沟的孔隙空间,封闭排气通道,产生水阻现象,并影响膜下孔隙气体从砂沟排气系统中的正常排出;③平原水库蓄水初期,土工膜缺陷渗漏,渗水接触地下水后,会挤占土工膜膜下非饱和土孔隙气体空间,并引起库区内地下水位的整体上升,促使非饱和土中孔隙气体聚集、上升,并引起土工膜产生局部隆起的鼓胀变形,表现为气胀现象。
For the plain reservoirs with geomembrane seepage prevention reservoir, the initial leakage of geomembrane and the seepage of geomembrane defect can easily cause the accumulation and increase of the pore gas in the unsaturated soil layer under the geomembrane of the reservoir area, and cause the local elevation of the geomembrane Bloating phenomenon. The mechanism of inflatable deformation of geomembrane caused by reservoir water seepage was analyzed. A large-scale special inflation test equipment was developed. The inflated area and non-infiltration area were used to simulate the inflation phenomenon caused by the geomembrane defect. The conclusions are as follows: ①For the geomembrane without defect, when the groundwater level is constant, the reservoir water will not produce the inflation of the geomembrane; ② In the early stage of the impoundment of the plain reservoir, the seepage of the geomembrane may infiltrate under the original membrane Sand pore space, the closed exhaust channel, resulting in water resistance phenomenon, and affect the membrane pore gas from the sand drainage system, the normal discharge; ③ plain reservoirs early, geomembrane defect leakage, seepage after contact with groundwater , Will occupy the space under the geomembrane subatmospheric pore gas space and cause the overall elevation of groundwater level in the reservoir area to promote the accumulation and rise of the pore gas in the unsaturated soil and cause the local swelling of the geomembrane bulging deformation, Expansion phenomenon.