现阶段工程中常用的土工膜分类及主要原材料

现(xian)有(you)土(tu)工膜(mo)分为常(chang)规土(tu)工膜(mo)和(he)(he)复合土(tu)工膜(mo)。聚(ju)合物(wu)、沥青和(he)(he)合成橡(xiang)胶是常(chang)规土(tu)工膜(mo)的(de)主(zhu)(zhu)要(yao)原材(cai)料(liao)，其中(zhong)又以聚(ju)合物(wu)为主(zhu)(zhu)。聚(ju)合物(wu)土(tu)工膜(mo)的(de)生产方式(shi)有(you)3种(zhong)，分别是吹塑法(fa)、压延(yan)法(fa)和(he)(he)挤(ji)压法(fa)。常(chang)规土(tu)工膜(mo)按聚(ju)合物(wu)种(zhong)类划分，可(ke)主(zhu)(zhu)要(yao)分为聚(ju)氯乙烯（PVC）土(tu)工膜(mo)、聚(ju)乙烯（PE）土(tu)工膜(mo)和(he)(he)高(gao)密度聚(ju)乙烯（HDPE）土(tu)工膜(mo)，它们的(de)物(wu)理力学指标如表1所示。

PVC土(tu)工(gong)(gong)膜(mo)的(de)密(mi)度(du)、熔点(dian)(dian)和抗拉(la)强度(du)在(zai)三者之中最(zui)大(da)(da)。优点(dian)(dian)是在(zai)施工(gong)(gong)期间(jian)(jian)和运行期间(jian)(jian)，土(tu)工(gong)(gong)膜(mo)能承(cheng)受(shou)更大(da)(da)的(de)拉(la)应力，更不易损坏，且能更好地适(shi)应极端高(gao)温工(gong)(gong)况；缺点(dian)(dian)是每(mei)片(pian)土(tu)工(gong)(gong)膜(mo)之间(jian)(jian)的(de)焊接(jie)困难，且由于密(mi)度(du)过大(da)(da)，相同体积的(de)土(tu)工(gong)(gong)膜(mo)需要更多

的车(che)辆运输(shu)，这会导致(zhi)造价上(shang)升及效率下降。

HDPE土工膜(mo)(mo)的(de)(de)密度、熔(rong)点(dian)(dian)在三(san)者之(zhi)中最低(di)，抗拉强(qiang)度中等，断裂(lie)伸长率最高。优点(dian)(dian)是由于密度低(di)，运输所(suo)产生的(de)(de)费用(yong)下降且效率提(ti)升；断裂(lie)伸长率高说明(ming)HDPE土工膜(mo)(mo)的(de)(de)塑形优良，抗冲击性(xing)(xing)能(neng)(neng)好；熔(rong)点(dian)(dian)低(di)表明(ming)每片土工膜(mo)(mo)之(zhi)间的(de)(de)焊接(jie)容易。缺点(dian)(dian)是熔(rong)点(dian)(dian)最低(di)，不(bu)能(neng)(neng)用(yong)于极端(duan)高温工况(kuang)。另(ling)外，HDPE是一种结晶度高、非极性(xing)(xing)的(de)(de)热塑性(xing)(xing)树脂，具有耐化(hua)学品(pin)的(de)(de)特性(xing)(xing)，当废料场含有不(bu)确定的(de)(de)化(hua)学成(cheng)分时，可优先(xian)选用(yong)HDPE土工膜(mo)(mo)。

PE土(tu)(tu)(tu)工(gong)(gong)(gong)膜在(zai)三者之中，密(mi)度低(di)，熔(rong)(rong)点(dian)、断裂伸(shen)长率(lv)中等(deng)，抗(kang)拉强度最(zui)低(di)。优(you)点(dian)是PE土(tu)(tu)(tu)工(gong)(gong)(gong)膜易(yi)(yi)运输(shu)，所(suo)产(chan)生的费用低(di)且工(gong)(gong)(gong)作效(xiao)率(lv)高，熔(rong)(rong)点(dian)中等(deng)代(dai)表(biao)了每片土(tu)(tu)(tu)工(gong)(gong)(gong)膜焊接容易(yi)(yi)且能适应极端温度工(gong)(gong)(gong)况，断裂伸(shen)长率(lv)中等(deng)代(dai)表(biao)了PE土(tu)(tu)(tu)工(gong)(gong)(gong)膜拥有(you)良(liang)好的塑形，有(you)一定(ding)的抗(kang)冲击性能。缺点(dian)是抗(kang)拉强度最(zui)低(di)，PE土(tu)(tu)(tu)工(gong)(gong)(gong)膜在(zai)施工(gong)(gong)(gong)期(qi)和运行(xing)期(qi)间，所(suo)能承受的拉应力有(you)限，容易(yi)(yi)发生破坏。

复合(he)土工(gong)(gong)膜是在常规土工(gong)(gong)膜的基础(chu)上(shang)通过一些特定的制(zhi)造方法(fa)(fa)，将土工(gong)(gong)织物(wu)附着在常规土工(gong)(gong)膜上(shang)，形成复合(he)形式(shi)的土工(gong)(gong)膜。复合(he)土工(gong)(gong)膜制(zhi)造方法(fa)(fa)有流延和压延。常用的复合(he)土工(gong)(gong)膜有一布一膜和两布一膜。

由于土工(gong)织(zhi)物(wu)的加(jia)入，复合(he)(he)土工(gong)膜(mo)比常规(gui)土工(gong)膜(mo)拥有更高的抗拉强度(du)，且土工(gong)织(zhi)物(wu)作为土工(gong)膜(mo)的保护层，可以大大增强土工(gong)膜(mo)的防破坏能力，另外(wai)，复合(he)(he)土工(gong)膜(mo)的界(jie)面(mian)剪切性能也优于常规(gui)土工(gong)膜(mo)。对于较厚的土工(gong)织(zhi)物(wu)，复合(he)(he)土工(gong)膜(mo)还(hai)具备沿织(zhi)物(wu)平面(mian)方(fang)向在其内(nei)部传输水和气(qi)的能力。