土工膜胀破压力约为土工布胀破压力的50%~60%

复合土(tu)工(gong)(gong)(gong)膜(mo)由土(tu)工(gong)(gong)(gong)膜(mo)和(he)土(tu)工(gong)(gong)(gong)布(bu)组(zu)成，在平原水库(ku)防渗中(zhong)(zhong)，土(tu)工(gong)(gong)(gong)布(bu)起保护(hu)加(jia)强作用(yong)，并对复合土(tu)工(gong)(gong)(gong)膜(mo)鼓(gu)胀(zhang)(zhang)(zhang)(zhang)变(bian)形有重要影响。将土(tu)工(gong)(gong)(gong)布(bu)气胀(zhang)(zhang)(zhang)(zhang)现象简化为环向约(yue)束球形鼓(gu)胀(zhang)(zhang)(zhang)(zhang)变(bian)形模型(xing)，借助(zhu)(zhu)于土(tu)工(gong)(gong)(gong)布(bu)布(bu)下铺设的不透气薄膜(mo)，通过鼓(gu)胀(zhang)(zhang)(zhang)(zhang)变(bian)形专(zhuan)门试(shi)验设备，进(jin)行了鼓(gu)胀(zhang)(zhang)(zhang)(zhang)变(bian)形试(shi)验，研究了土(tu)工(gong)(gong)(gong)布(bu)鼓(gu)胀(zhang)(zhang)(zhang)(zhang)的变(bian)形特征和(he)力学特性，并借助(zhu)(zhu)显微镜着重分析了土(tu)工(gong)(gong)(gong)布(bu)变(bian)形过程中(zhong)(zhong)纤维结(jie)构(gou)变(bian)化过程和(he)胀(zhang)(zhang)(zhang)(zhang)破机理(li)。

结果表(biao)明(ming)：1）土(tu)工(gong)(gong)膜胀破压力(li)约(yue)为土(tu)工(gong)(gong)布胀破压力(li)的50%~60%，可见膜上土(tu)工(gong)(gong)布除起保(bao)护(hu)作(zuo)用(yong)(yong)外(wai)，还(hai)会对土(tu)工(gong)(gong)膜变(bian)形产生约(yue)束作(zuo)用(yong)(yong)，并增加其(qi)抵抗变(bian)形的能力(li)；

2）土工布在鼓胀变形中，张应力-应变曲线(xian)表现为塑性(xing)变形特征，可分为线(xian)弹(dan)性(xing)、屈服、强化和胀破(po)拉断共(gong)4个阶段；

3）土工布鼓(gu)胀(zhang)变形形状为半球(qiu)状，撕裂点(dian)一般(ban)出现在冠顶处，且进一步扩展(zhan)为纺锤形撕裂破(po)坏，微观结(jie)(jie)构分析表明针(zhen)刺(ci)短纤(xian)维(wei)形成的(de)缠(chan)结(jie)(jie)点(dian)具(ju)有(you)一定的(de)缠(chan)结(jie)(jie)力，缠(chan)结(jie)(jie)点(dian)之间的(de)纤(xian)维(wei)具(ju)有(you)一定的(de)拉伸强(qiang)度，缠(chan)结(jie)(jie)点(dian)缠(chan)结(jie)(jie)力逐渐失效和纤(xian)维(wei)断裂是土工布鼓(gu)胀(zhang)变形破(po)坏的(de)主要原(yuan)因；

4）土工(gong)布(bu)单位(wei)面积质(zhi)量越(yue)(yue)大，纤维和缠结点越(yue)(yue)密，可承受的鼓胀压力(li)越(yue)(yue)大，即抵抗鼓胀变形的能(neng)力(li)越(yue)(yue)强(qiang)。研究成果对(dui)(dui)于分(fen)析膜上土工(gong)布(bu)对(dui)(dui)土工(gong)膜鼓胀变形强(qiang)度的贡献具有一(yi)定(ding)的实(shi)际意义(yi)。