土工膜缺陷对土石坝渗流影响及安全性评价

土工膜缺陷对(dui)土(tu)(tu)石坝渗(shen)流的影(ying)响采用(yong)有限元法(fa)，结合工(gong)程实际建(jian)立二维数值(zhi)模型，从土(tu)(tu)工(gong)膜(mo)缺陷尺(chi)寸、位置角(jiao)度进行(xing)仿真分析，研(yan)究土(tu)(tu)工(gong)膜(mo)缺陷对(dui)土(tu)(tu)石坝渗(shen)流场的影(ying)响。

为便(bian)于计算(suan)，土工(gong)膜按渗透系数等(deng)效放(fang)大的原则将厚度放(fang)大100倍进行模(mo)拟。模(mo)型上下游(you)(you)各截(jie)取一(yi)倍坝高，将防渗墙(qiang)底(di)部(bu)以下7．2m作为底(di)部(bu)边(bian)(bian)界(jie)。模(mo)型离散后，节点数为7652，单元数为14872。计算(suan)时，模(mo)型底(di)部(bu)和(he)上下游(you)(you)边(bian)(bian)界(jie)均设为不透水边(bian)(bian)界(jie)，正常蓄水位(wei)以下上游(you)(you)坝坡设为已(yi)知水头边(bian)(bian)界(jie)，下游(you)(you)坝坡设为出逸边(bian)(bian)界(jie)。

缺(que)(que)陷(xian)(xian)(xian)(xian)破(po)损处(chu)渗(shen)(shen)(shen)透(tou)(tou)系数(shu)应为(wei)(wei)无(wu)限大(da)，考虑土工膜渗(shen)(shen)(shen)透(tou)(tou)系数(shu)较(jiao)小(xiao)(xiao)，将其(qi)渗(shen)(shen)(shen)透(tou)(tou)系数(shu)取为(wei)(wei)100m/s。缺(que)(que)陷(xian)(xian)(xian)(xian)渗(shen)(shen)(shen)漏对缺(que)(que)陷(xian)(xian)(xian)(xian)附(fu)近渗(shen)(shen)(shen)流(liu)场影(ying)(ying)(ying)(ying)响(xiang)明显(xian)，随(sui)着水头与(yu)缺(que)(que)陷(xian)(xian)(xian)(xian)尺(chi)寸的(de)增大(da)，坝(ba)体各渗(shen)(shen)(shen)流(liu)要素如渗(shen)(shen)(shen)流(liu)坡降、单宽(kuan)渗(shen)(shen)(shen)流(liu)量等逐渐(jian)增大(da)，坝(ba)基(ji)防(fang)渗(shen)(shen)(shen)墙底部(bu)(bu)(bu)渗(shen)(shen)(shen)流(liu)坡降、单宽(kuan)渗(shen)(shen)(shen)流(liu)量等逐渐(jian)减小(xiao)(xiao);当缺(que)(que)陷(xian)(xian)(xian)(xian)尺(chi)寸小(xiao)(xiao)于0．2m时(shi)，下部(bu)(bu)(bu)缺(que)(que)陷(xian)(xian)(xian)(xian)对坝(ba)体与(yu)坝(ba)基(ji)防(fang)渗(shen)(shen)(shen)墙底部(bu)(bu)(bu)渗(shen)(shen)(shen)流(liu)要素影(ying)(ying)(ying)(ying)响(xiang)最大(da)，中部(bu)(bu)(bu)缺(que)(que)陷(xian)(xian)(xian)(xian)影(ying)(ying)(ying)(ying)响(xiang)次之(zhi)，上部(bu)(bu)(bu)缺(que)(que)陷(xian)(xian)(xian)(xian)影(ying)(ying)(ying)(ying)响(xiang)最小(xiao)(xiao);当缺(que)(que)陷(xian)(xian)(xian)(xian)尺(chi)寸达(da)到(dao)0.2m时(shi)，中部(bu)(bu)(bu)缺(que)(que)陷(xian)(xian)(xian)(xian)对坝(ba)体与(yu)坝(ba)基(ji)防(fang)渗(shen)(shen)(shen)墙底部(bu)(bu)(bu)渗(shen)(shen)(shen)流(liu)要素影(ying)(ying)(ying)(ying)响(xiang)最大(da)，下部(bu)(bu)(bu)缺(que)(que)陷(xian)(xian)(xian)(xian)影(ying)(ying)(ying)(ying)响(xiang)次之(zhi)，上部(bu)(bu)(bu)缺(que)(que)陷(xian)(xian)(xian)(xian)影(ying)(ying)(ying)(ying)响(xiang)最小(xiao)(xiao)。