Air expansion caused by leakage water resulting from geomembrane defects
-
摘要: 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。Abstract: In the initial storage period of the plain reservoir using geomembrane as anti-seepage materials of reservoir basin, the leakage water resulting from geomembrane defects is easy to induce the pore-air in the unsaturated soil under geomembrane gathering and rising, and the pore-air will lead to air expansion of the geomembrane with local swelling. The mechanism of air expansion phenomenon resulting from the leakage water is analyzed. A special large-scale test instrument for the air expansion of geomembrane is developed. Air expansion tests in seepage area and anti-seepage area are conducted to simulate the air expansion phenomenon caused by the leakage water resulting from geomembrane defects. The conclusions are drawn as follows: (1) when the groundwater level is invariant, there will be no geomembrane air expansion phenomenon during the storage period; (2) in the initial storage period of plain reservoirs, water leaks from the geomembrane defects, intrudes the porous space of sand ditches under geomembrane, seals off exhaust passages, and causes water resistance phenomenon, and then affects pore-air exhaust from sand ditch exhaust system regularly; (3) in the initial storage period of plain reservoirs, water leaks from the geomembrane defects, and after the leakage water meets the underground water, leakage water will squeeze the space of pore-air in unsaturated soil under geomembrane, induce the overall rising of groundwater level in the reservoir area and gathering and rising of pore-air in unsaturated soil, finally, it causes local expansive deformation of the geomembrane, that is, the air expansion phenomenon.-
Keywords:
- plain reservoir /
- anti-seepage of reservoir basin /
- defected geomembrane /
- leakage /
- air expansion
Abstract:
In the initial storage period of the plain reservoir using geomembrane as anti-seepage materials of reservoir basin, the leakage water resulting from geomembrane defects is easy to induce the pore-air in the unsaturated soil under geomembrane gathering and rising, and the pore-air will lead to air expansion of the geomembrane with local swelling. The mechanism of air expansion phenomenon resulting from the leakage water is analyzed. A special large-scale test instrument for the air expansion of geomembrane is developed. Air expansion tests in seepage area and anti-seepage area are conducted to simulate the air expansion phenomenon caused by the leakage water resulting from geomembrane defects. The conclusions are drawn as follows: (1) when the groundwater level is invariant, there will be no geomembrane air expansion phenomenon during the storage period; (2) in the initial storage period of plain reservoirs, water leaks from the geomembrane defects, intrudes the porous space of sand ditches under geomembrane, seals off exhaust passages, and causes water resistance phenomenon, and then affects pore-air exhaust from sand ditch exhaust system regularly; (3) in the initial storage period of plain reservoirs, water leaks from the geomembrane defects, and after the leakage water meets the underground water, leakage water will squeeze the space of pore-air in unsaturated soil under geomembrane, induce the overall rising of groundwater level in the reservoir area and gathering and rising of pore-air in unsaturated soil, finally, it causes local expansive deformation of the geomembrane, that is, the air expansion phenomenon.
| [1] |
殷宗泽) 土工原理[M].北京:中国水利水电出版社,2007. (YIN Zong-ze. Principles of soil mechanics[M] Beijing: China Water Power Press,2007. (in Chinese)) |
| [2] | FREDLUND D G,RAHARDJO H 非饱和土力学[M]. 陈仲颐, 张在明, 陈愈炯, 等译.北京:中国建筑工业出版社,1997. (FREDLUND D G, RAHARDJO H. Soil mechanics for unsaturated soils[M]. CHEN Zhong-yi, ZHANG Zai-ming, CHEN Yu-jiong, et al, trans. Beijing: China Architecture and Building Press, 1997. (in Chinese)) |
| [3] |
包承纲). 非饱和土的性状及膨胀土边坡稳定问题[J]. (岩土工程学报), 2004,26(1):1-15. (BAO Cheng-gang. Behavior of unsaturated soil and stability of expansive soil slope[J]. Chinese Journal of Geotechnical Engineering. 2004, 26(1): 1-15. (in Chinese)) |
| [4] |
王永胜),(谢定义),(郭庆国). 非饱和土中气体的运动特性与渗气系数的测定[J]. (西北水电), 1993(1):46-49. (WANG Yong-sheng, XIE Ding-yi, GUO Qing-guo. Determination of motion characteristics of gas and coefficient of air permeability in the unsaturated soil[J]. Northwest Water Power, 1993(1): 46-49.( (in Chinese)) |
| [5] | GIDDA T, CANN D, STIVER W H,et al. Airflow dispersion in unsaturated soil[J]. Journal of Contaminant Hydrology, 2006,82(1/2):118-132. |
| [6] |
张士林). 土壤气压势的计算方法研究[J]. (西部探矿工程), 2006(12):10-11. (ZHANG Shi-lin. The calculation method of the soil barometric potential[J]. West-China Exploration Engineering, 2006(12): 10-11.( (in Chinese)) |
| [7] | CAMPBELL G S. Soil water potential measurement: An overview[J]. Irrigation Science, 1988,9(4):265-273. |
| [8] |
刘 磊,薛 强,梁 冰,等. 垃圾填埋场封场后气体产出及释放规律研究术[J]. (环境卫生工程), 2010,18(1):19-21. (LIU Lei, XUE Qiang, LIANG Bing, et al. Landfill gas generation and emission in closed landfill sites[J]. Environmental Sanitation Engineering,2010,18(1): 19-21. (in Chinese) |
下载:
