人工胶结粉质粘土土力学特性的状态相关性试验

State-Dependent Experiments on Mechanical Characteristics of Artificial Cemented Silty Clayey Soils

在土中掺入一定量的胶凝材料形成具有结构性的人工胶结土被广泛应用于岩土体的改良。然而,结构性的存在使得胶结土呈现出复杂的力学行为,故针对胶结结构性土的力学行为的定量化分析具有十分重要意义。以水泥胶结土为例,通过室内单元试验系统分析其力学特性的状态相关性。研究结果表明:①在相同围压下,孔隙比相对较小的胶结土在剪切过程中愈呈现出应变软化现象,随着固结围压增大,逐步向应变硬化过渡,间接指明胶结土适用于浅层加固这一特点;②胶结土和重塑土在0~1500kPa之内的等向固结曲线均呈现不同程度上的弯折,其中重塑土最显著,孔隙比越小的胶结土越不明显,表明胶结性的存在与否或强弱程度显著影响土体等向压缩特性;③胶结土的残余强度和临界强度线的斜率受初始状态量(孔隙比、胶结性)影响较小,故认为它们是一种固有状态无关的力学参数。

A certain amount of cementitious material is mixed into the soil to form a structural artificial cemented soil,which could be widely used in the improvement of geomaterials.However,the existence of this structure makes the cemented soil demonstrates complex mechanical behaviors,so it is of great significance to quantitatively analyze the mechanical behavior of the cemented structural soil.This paper presents a case history of evaluating the mechanical behavior of the cemented soil.The test system analyzes the state dependence of the mechanical properties.The results show that:(1)Under the same confining pressure,the cemented soil with a relatively small void ratio shows more and more strain softening phenomenon during the shear process,and with the increase of the consolidation confining pressure,it gradually transitions to the strain hardening,which implying that the cemented soil is suitable for the shallow reinforcement;(2)The isotropic consolidation curves of the cemented soil and the remolded soil within 0~1500kPa all showed different degrees of bending,among which the remolded soil was the most significant,and the less obvious the cemented soil with relatively small void ratio,indicating that the existence or strength of the cementing force significantly affected the isotropic compression characteristics of the soil;(3)The residual strength of the cemented soil and the slope of the critical strength line are less affected by the initial state quantity(void ratio,cementation),so they are considered to be a mechanical parameter independent of the intrinsic state.