复合土工膜与其他材料之间的摩擦特性有哪些？

复合土工膜由土(tu)工膜和(he)土(tu)工织(zhi)物组成，相(xiang)比(bi)其他防(fang)(fang)(fang)渗材(cai)料，具有优越的(de)延展性(xing)及防(fang)(fang)(fang)渗性(xing)，不(bu)仅能(neng)适应坝体的(de)大(da)变形，并(bing)可(ke)以发挥很(hen)好(hao)的(de)防(fang)(fang)(fang)渗作用，主要用于土(tu)石坝、堤防(fang)(fang)(fang)、围堰等水(shui)库工程(cheng)，以及蓄水(shui)池、渠道、垃圾(ji)填埋场等防(fang)(fang)(fang)渗工程(cheng)。

已建的(de)(de)水(shui)库工(gong)(gong)(gong)(gong)程(cheng)中，土(tu)(tu)石(shi)(shi)坝的(de)(de)数量(liang)达(da)90%以上，其(qi)中土(tu)(tu)工(gong)(gong)(gong)(gong)膜(mo)防(fang)渗(shen)土(tu)(tu)石(shi)(shi)坝与同时代起步的(de)(de)碾压(ya)混(hun)凝(ning)土(tu)(tu)坝和混(hun)凝(ning)土(tu)(tu)面(mian)板(ban)堆石(shi)(shi)坝相比(bi)，发(fa)展明显滞缓(huan)，在土(tu)(tu)工(gong)(gong)(gong)(gong)设计中也涉及一(yi)些特(te)殊的(de)(de)问题。当在斜坡上铺设土(tu)(tu)工(gong)(gong)(gong)(gong)膜(mo)时，土(tu)(tu)工(gong)(gong)(gong)(gong)膜(mo)与其(qi)他(ta)材(cai)料(包括土(tu)(tu)类(lei))之(zhi)间的(de)(de)摩擦(ca)(ca)特(te)性(xing)，是工(gong)(gong)(gong)(gong)程(cheng)设计时一(yi)个非常(chang)重(zhong)要(yao)的(de)(de)控制指标(biao)。土(tu)(tu)工(gong)(gong)(gong)(gong)膜(mo)表面(mian)较(jiao)为光滑，它与其(qi)他(ta)材(cai)料间与土(tu)(tu)类(lei)材(cai)料相比(bi)的(de)(de)摩擦(ca)(ca)角小，易(yi)沿斜面(mian)滑动，往往构成优(you)先(xian)滑动面(mian)。若设计中考虑界面(mian)摩擦(ca)(ca)角较(jiao)小，则(ze)边坡、坝坡坡度必然过(guo)缓(huan)，势(shi)必会(hui)加大工(gong)(gong)(gong)(gong)程(cheng)量(liang)，造(zao)成经济浪(lang)费(fei);反之(zhi)，安全性(xing)能(neng)大幅度降低(di)。因此(ci)正(zheng)确评价土(tu)(tu)工(gong)(gong)(gong)(gong)膜(mo)界面(mian)的(de)(de)摩擦(ca)(ca)特(te)性(xing)是工(gong)(gong)(gong)(gong)程(cheng)中亟待解决的(de)(de)问题之(zhi)一(yi)。

坝体在(zai)施工及运行过(guo)程(cheng)(cheng)中各(ge)种外(wai)部荷载作(zuo)用，往往会发生沉降变形及向(xiang)下游(you)的(de)(de)水平位移(yi)，在(zai)土(tu)工膜(mo)与面(mian)板(ban)联合防渗(shen)(shen)结(jie)构中，这一(yi)位移(yi)通过(guo)周边结(jie)构传递给(ji)垫(dian)(dian)(dian)层(ceng)表面(mian)的(de)(de)土(tu)工膜(mo)，从(cong)而使得土(tu)工膜(mo)与垫(dian)(dian)(dian)层(ceng)材料之间(jian)发生接(jie)触剪(jian)切作(zuo)用，最终产生拉伸变形乃至破坏。大量工程(cheng)(cheng)实例表明，在(zai)土(tu)石坝工程(cheng)(cheng)设计中，垫(dian)(dian)(dian)层(ceng)所(suo)采(cai)用的(de)(de)材料是设计人员需要(yao)(yao)考虑的(de)(de)非(fei)常重要(yao)(yao)问题，当土(tu)工膜(mo)防渗(shen)(shen)体铺设在(zai)大坝的(de)(de)上游(you)面(mian)，作(zuo)为防渗(shen)(shen)斜墙时，对坝坡的(de)(de)稳定性(xing)影响较大。

在温(wen)(wen)(wen)带大(da)陆性(xing)(xing)(xing)气(qi)候(hou)地(di)区，常在夏季较炎热(re)的环境下(xia)施(shi)工(gong)(gong)(gong)(gong)，温(wen)(wen)(wen)度(du)(du)(du)较高时(shi)(shi)，施(shi)工(gong)(gong)(gong)(gong)面(mian)温(wen)(wen)(wen)度(du)(du)(du)经常达40℃，有(you)(you)(you)(you)时(shi)(shi)甚至能(neng)达到50℃;在土(tu)工(gong)(gong)(gong)(gong)膜上铺筑(zhu)现浇(jiao)砂浆或现浇(jiao)混(hun)凝(ning)土(tu)，水(shui)化(hua)(hua)(hua)热(re)过(guo)程，可(ke)使(shi)土(tu)工(gong)(gong)(gong)(gong)膜环境温(wen)(wen)(wen)度(du)(du)(du)更(geng)高，工(gong)(gong)(gong)(gong)作环境受到温(wen)(wen)(wen)度(du)(du)(du)的严峻挑战。目前，因土(tu)工(gong)(gong)(gong)(gong)膜为高分子材(cai)料且多为黑色，性(xing)(xing)(xing)能(neng)受温(wen)(wen)(wen)度(du)(du)(du)影(ying)响(xiang)很大(da)，外界(jie)温(wen)(wen)(wen)度(du)(du)(du)变(bian)化(hua)(hua)(hua)会使(shi)土(tu)工(gong)(gong)(gong)(gong)膜基本(ben)力学性(xing)(xing)(xing)能(neng)发(fa)生变(bian)化(hua)(hua)(hua)，温(wen)(wen)(wen)差过(guo)大(da)有(you)(you)(you)(you)可(ke)能(neng)造(zao)成(cheng)张拉力过(guo)大(da)而(er)滑落，或因变(bian)形过(guo)大(da)土(tu)工(gong)(gong)(gong)(gong)膜上覆砌(qi)块等保护层滑落失(shi)去(qu)防渗能(neng)力，特别在施(shi)工(gong)(gong)(gong)(gong)阶(jie)段(duan)或未输水(shui)期(qi)间更(geng)易发(fa)生破坏。有(you)(you)(you)(you)关土(tu)工(gong)(gong)(gong)(gong)膜的研(yan)究中，主要侧重于(yu)构造(zao)和施(shi)工(gong)(gong)(gong)(gong)方面(mian)，少有(you)(you)(you)(you)温(wen)(wen)(wen)度(du)(du)(du)与材(cai)料剪(jian)切(qie)性(xing)(xing)(xing)能(neng)之间关系(xi)的研(yan)究，本(ben)次试验(yan)研(yan)究将明确探究试验(yan)温(wen)(wen)(wen)度(du)(du)(du)对(dui)土(tu)工(gong)(gong)(gong)(gong)膜界(jie)面(mian)摩擦的影(ying)响(xiang)。研(yan)究成(cheng)果可(ke)正确认识在不(bu)同试验(yan)温(wen)(wen)(wen)度(du)(du)(du)下(xia)复合(he)土(tu)工(gong)(gong)(gong)(gong)膜与不(bu)同剪(jian)切(qie)材(cai)料的界(jie)面(mian)摩擦参数的变(bian)化(hua)(hua)(hua)规律，对(dui)于(yu)工(gong)(gong)(gong)(gong)程设计人员(yuan)评价坝坡稳(wen)定(ding)性(xing)(xing)(xing)具有(you)(you)(you)(you)重要的指导意(yi)义。