剑麻纤维复合基材土岩界面剪切性能试验

Experimental study on shear properties of soil-rock interface of sisal fiber composite material

为揭示剑麻纤维掺量与界面粗糙度对土-岩界面剪切力学性能的影响规律,采用表面起伏的混凝土模块作为岩面相似材料,进行了一系列的改进室内直剪试验,并结合扫描电镜试验进一步分析了剑麻纤维参与强化界面剪切性能的机理。结果表明:剑麻纤维通过提高黏聚力提高土-混凝土界面间的剪切力学性能;纤维添加量为0.8%的土-混凝土界面黏聚力提高80%~500%,内摩擦角提高10%~20%;界面粗糙度主要通过提高黏聚力增强界面剪切力学性能,6.5 mm粗糙度的界面黏聚力增量为7~15.5.kPa,提高20%~300%;对于素土界面和掺纤维界面,粗糙度对土-混凝土界面间剪切力学性能的强化表现为2种模式,加入纤维的界面黏聚力关于粗糙度的增长关系上,粗糙度的最优值出现在较小区间(0~2.5 mm)。

In order to study the influence of sisal fiber and interface roughness on the shear mechanical properties of soil-rock interface,concrete modules with rough surface were used as the rock surface similar material and a series of indoor shear tests were carried out.Combined with the SEM test,the mechanism of sisal fiber participating in the strengthening of the interface is further analyzed.The results show that sisal fiber can improve the shear mechanical properties of soil-concrete interface by improving the cohesion.The addition of 0.8%by weight increases the interfacial bond strength of soil-cement interface by 0.8-5 times and the internal friction angle by 0.1-0.2 times.The interface roughness mainly enhances the shear mechanical performance of the interface by improving the bond strength.For an interface roughness of 6.5 mm,the increase of interfacial bond strength ranges from 7 kPa to 15.5 kPa,resulting in an improvement of 0.2-3 times.The enhancement of roughness on the shear mechanical performance of the soil-cement interface exhibits two distinct patterns for the plain soil interface and the fiber-reinforced interface.Regarding the relationship between interfacial bond strength and roughness for the fiber-reinforced interface,the optimal value of roughness appears within a smaller range(0-2.5 mm).