中文摘要：

为研究含砂量对聚丙烯纤维土加筋黏性土强度的影响及其机制,将2%,4%,6%,8%和10%素土重的砂分别与聚丙烯纤维加筋黏性土混合均匀,共配制7组土样,进行无侧限抗压强度试验和直剪试验。运用扫描电镜（SEM）,观察和分析纤维在土样中的形态特征。试验结果表明,黏性土中的含砂量对纤维加筋土的强度有重要影响。在砂与纤维表面的摩擦力和黏土颗粒对纤维的黏结作用下,纤维土的无侧限抗压强度和黏聚力随含砂量的增加先增加后减少,纤维土的内摩擦角大小与掺砂量成正比。在掺砂量为4%时,纤维的加筋作用得到最大发挥,此时土样的无侧限抗压强度达到最大值。此外,在黏土中砂的碰撞或挤压作用下,纤维的形状发生改变,从而增加纤维的粗糙度,加强界面之间的力学作用。

英文摘要：

The purpose of this study was to identify the influences of sand content on the strength and mechanical behaviors of polypropylene fiber reinforced clay soil.Sand was included in polypropylene fiber reinforced clay soil（with 0.25% fiber content） at five different percentagesi,.e.2%,4%,6%,8% and 10% by weight of raw soil.Seven groups of samples were prepared and subjected to unconfined compression and direct shear test.The evolution of the morphological structure of fiber surfaces in soil matrix was characterized by using scanning electron microscopy（SEM）.The result shows that the bond strengthes between fibers and soil matrix,and the associated interfacial friction between sand particles and fibers have significant influences on the strength behavior of reinforced soil.Fiber inclusion increases the strength of clay soil.The unconfined compressive strength and cohesion of soil increase with sand content,but decrease when the sand content is lower than 4%;and the angle of internal friction increases with increase of sand content.The maximum value of unconfined compressive strength is observed at the optimum sand content of 4%.Besides,an increase of fiber superficial roughness is observed due to the impact between sands and fibers during mixing or compressing,which mechanically damages the surface of the fiber.