库水降落时坝面缺陷土工膜的局部抗滑稳定性
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摘要
在分析坝面土工膜缺陷渗漏和失稳机理的基础上,采用非恒定非饱渗流理论,计算坝面土工膜防渗土石坝库水降落时的瞬态渗流场,获取膜后孔压动态分布规律,进而分析土工膜的局部抗滑稳定性随库水降落时的变化特性,同时对库水降落速度、缺陷属性、垫层透水性进行敏感性分析.结果表明:(1)库水降落速度对坝面完好土工膜的局部抗滑稳定性影响很小,但对缺陷土工膜影响显著,土工膜存在局部失稳可能,库水降落速度越大,安全系数降幅越大;(2)土工膜缺陷位置对其局部抗滑稳定性影响显著,缺陷位置越高,安全系数降幅越大;(3)缺陷尺寸对土工膜局部稳定性影响不大;双缺陷较单缺陷相比,其对土工膜局部稳定性的影响不明显;(4)垫层的透水性对土工膜局部抗滑稳定性影响较为显著,透水性好的垫层对土工膜抗滑稳定有利.
Based on the discussion of defect-induced leakage and instability of geomembrane on upstream dam surface,the transient seepage field of a geomembrane faced earth-rock dam was calculated to get the pore water distribution by using the unsteady and saturated-unsaturated seepage theory. The change characteristics of the local anti-sliding stability safety factor of geomembrane under the drawdown of reservoir were finely analyzed. The sensitivity analysis of the drawdown velocity,defect properties and permeability of cushion layer was also carried out.The results show that:( 1) the drawdown velocity of reservoir has little influence on the safety factor of intact geomembrane,but has significant influence on geomembrane with defect. Higher drawdown velocity will cause much bigger loss of safety factor of geomembrane,which will possibly result in local instability of geomembrane;( 2) the defect position significantly affects the local stability of geomembrane,and the higher defect position is,the smaller safety factory is;( 3) the size of defect has little influence on safety factor; the multiple defects have little influence on the local stability of geomembrane;( 4) the permeability of cushion layer has big impact on safety factor of geomembrane,and strong permeable cushion can prevent the local instability of geomembrane.
Based on the discussion of defect-induced leakage and instability of geomembrane on upstream dam surface,the transient seepage field of a geomembrane faced earth-rock dam was calculated to get the pore water distribution by using the unsteady and saturated-unsaturated seepage theory. The change characteristics of the local anti-sliding stability safety factor of geomembrane under the drawdown of reservoir were finely analyzed. The sensitivity analysis of the drawdown velocity,defect properties and permeability of cushion layer was also carried out.The results show that:( 1) the drawdown velocity of reservoir has little influence on the safety factor of intact geomembrane,but has significant influence on geomembrane with defect. Higher drawdown velocity will cause much bigger loss of safety factor of geomembrane,which will possibly result in local instability of geomembrane;( 2) the defect position significantly affects the local stability of geomembrane,and the higher defect position is,the smaller safety factory is;( 3) the size of defect has little influence on safety factor; the multiple defects have little influence on the local stability of geomembrane;( 4) the permeability of cushion layer has big impact on safety factor of geomembrane,and strong permeable cushion can prevent the local instability of geomembrane.
引文
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[10]岑威钧,王蒙,杨志祥.(复合)土工膜防渗土石坝饱和-非饱和渗流特性[J].水利水电科技进展,2012,32(3):6-9Cen Weijun,Wang Meng,Yang Zhixiang. Partial saturated seepage properties of(composite)geomembrane earth-rock dams[J]. Advances in Science and Technology of Water Resources,2012,32(3):6-9
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[2]岑威钧,温朗昇,和浩楠.水库工程防渗土工膜的强度、渗漏与稳定若干关键问题[J].应用基础与工程科学学报,2017,25(6):1183-1192Cen Weijun,Wen Langsheng,He Haonan. Strength,leakage and stability problems of impermeable geomembrane for reservoir project[J]. Journal of Basic Science and Engineering,2017,25(6):1183-1192
[3]顾淦臣.复合土工膜或土工膜堤坝实例述评[J].水利水电技术,2002,33(12):26-32Gu Ganchen. Review of dams and dikes with composite geomembrane impervious structure[J]. Water Resources and Hydropower Engineering,2002,33(12):26-32
[4] Muller W W. HDPE geomembranes in geotechnics[M]. Berlin:Springer,2007
[5]胡利文,陈嘉鸥.土工膜微结构破损机理分析[J].岩土力学,2002,23(6):702-705Hu Liwen,Chen Jiaou. Analysis of damage for microstructure of geomembrane[J]. Rock and Soil Mechanics,2002,23(6):702-705
[6]岑威钧.土石坝防渗(复合)土工膜缺陷及其渗漏问题研究进展[J].水利水电科技进展,2016,36(1):1-7Cen Weijun. Advances in research of defects and leakage of(composite)geomembrane in earth-rock dams[J].Advances in Science and Technology of Water Resources,2016,36(1):1-7
[7]岑威钧,和浩楠,温朗昇.防渗土工膜的缺陷特性与缺陷渗漏研究进展[J].河海大学学报,2017,45(1):36-44Cen Weijun,He Haonan,Wen Langsheng. Research progress on defect property and defect induced leakage of impermeable geomembrane[J]. Journal of Hohai University(Nature Science),2017,45(1):36-44
[8]岑威钧,和浩楠,李邓军.土工膜缺陷对土石坝渗流特性的影响及控制措施[J].水利水电科技进展,2017,37(3):61-65Cen Weijun,He Haonan,Li Dengjun. Influence of geomembrane defect on seepage property of earth-rock dams and measures of seepage control[J]. Advances in Science and Technology of Water Resources,2017,37(3):61-65
[9]岑威钧,都旭煌,耿利彦,等.随机多缺陷条件下土工膜防渗土石坝渗漏特性[J].水利水电科技进展,2018,38(3):60-65Cen Weijun,Du Xuhuang,Geng Liyan,et al. Seepage property of geomembrane faced earth-rock dams due to random multiple defects on geomembrane[J]. Advances in Science and Technology of Water Resources,2018,38(3):60-65
[10]岑威钧,王蒙,杨志祥.(复合)土工膜防渗土石坝饱和-非饱和渗流特性[J].水利水电科技进展,2012,32(3):6-9Cen Weijun,Wang Meng,Yang Zhixiang. Partial saturated seepage properties of(composite)geomembrane earth-rock dams[J]. Advances in Science and Technology of Water Resources,2012,32(3):6-9
[11]沈振中,江沆,沈长松.复合土工膜缺陷渗漏试验的饱和-非饱和渗流有限元模拟[J].水利学报,2009,40(9):1091-1095Shen Zhenzhong,Jiang Hang,Shen Changsong. Numerical simulation of composite geomembrane defect leakage experiment based on saturated-unsaturated seepage theory[J]. Shuili Xuebao,2009,40(9):1094-1095