含石量对软质岩土石混合料土力学特性影响研究

A study of the effect of rock content on mechanical properties of soil-soft rock mixture

在中国西南地区边坡工程中大量存在含软岩的土石混合体(S-RM),其力学特性与软岩破碎特性有别于以往研究的块石强度较高的土石混合体。本文通过大型室内剪切仪开展了不同含石量(WBP)的剪切试验研究含石量对软岩土石混合体力学特性的影响,基于筛分试验研究软岩块石破碎特性,结果表明:当S-RM密度一定时,随着WBP的增加,SRM剪切强度增加,应变硬化现象增强; S-RM黏聚力随含石量的增加呈线性增长,内摩擦角在含石量为20%～60%时随含石量的增加呈线性增长; S-RM在剪切破坏过程中软岩块石出现破碎现象,当法向应力一定时,块石破碎率随土石混合体含石量增加而增长; S-RM块石破碎率随内摩擦角增加呈指数形式增长,表明块石之间咬合作用越大,块石的破碎程度越高。

The soil-rock mixture (S-RM) with soft rock block is widely used to be form fill slopes in southwest China. The mechanical properties and the soft block breakage properties of the S-RM are much different from the S-RM with high strength rock blocks previously studied. Based on large-scale shear test with different block proportion by weight (WBP) of S-RM, the mechanical properties of soil-soft rock mixture with different WBP are examined. Based on the sieving test before and after shear test, the breakage properties of soft rock blocks are studied. The results show that with the increasing WBP, the shear strength of S-RM increases and the strain-hardening phenomenon is more obvious when the density of S-RM samples are the same. The cohesive of S-RM increases linearly with the increasing WBP, and the internal frictional angle of S-RM also increases linearly when the WBP in the range of 20%~60%. The soft rock blocks occurs breakage in the failure process of S-RM. Under the same normal stress, the breakage ratio of rock blocks increases with the increasing WBP. The breakage ratio of rock blocks increases exponentially with the increasing internal frictional angle of S-RM, indicating that the breakage degree of rock blocks is higher when the biting between rock blocks is larger.