摘要
土石混合体具有强烈的非均质性、非均匀性、非连续性和环境依赖性,从土石混合体的非线性角度出发,采用分形几何理论对土石混合体的细观结构特性进行描述,明确土石混合体重塑样的备制工艺,重点探讨土石混合体单轴压缩条件下应力–应变特征以及与特征强度值之间的联系。得出以下几点结论:(1)含石量作为研究土石混合体力学特性的重要指标,与土石混合体的粒度分维数密切相关,二者满足幂函数关系;(2)根据试样的单轴压缩曲线结合数值计算结果,将土石混合体峰前应力–应变曲线分为接触压密阶段、弹性阶段、慢裂阶段、快裂阶段,峰后表现为应变软化特征;(3)随着试样含石量的增大,土石混合体的单轴抗压强度在含石量为50%时最大,轴向应变随含石量的增大而增加,土石混合体的径向变形更为敏感;(4)数值试验结合土石混合体的室内压缩试验,定义土石混合体土石结合裂缝开裂应力,并用LSR法计算开裂应力值,开裂应力、扩容应力和峰值应力呈线性函数关系。土石混合体具有细观结构的层次性和相似性,应用分形几何学的有关理论研究土石混合体的结构力学特征不失为一个好的思路,可以更好地了解土石混合体这类地质材料的细观结构和力学性质。
Rock and soil aggregates(RSA) has the properties of strong heterogeneity,heterogeneity,discontinuity and environment dependent. Based on the nonlinear property of RSA,the mesoscopic structure characteristics of RSA was analyzed by fractal geometry theory. Remodeling process of RSA samples was explicated,stress-strain relationship under uniaxial compression test and characteristic strength value of RSA samples were mainly discussed. Results show that:(1) As an important index to mechanical characteristics for RSA,stone content is closely associated with RSA granularity fractal dimension and meeting power function relationship.(2) According to uniaxial compression test,the pre-peak stress-strain curve of RSA is divided into four parts:contact consolidation stage,elastic stage,crack stable propagation stage and crack unstable propagation stage.(3) With the increase of stone content,uniaxial compressive strength reaches to maximum when stone content is 50%,axial strain is increasing with stone content,the radial deformation of earth-rock aggregate is more sensitive;(4) Analogy the mechanical properties of brittle rock and concrete,cracking initiation stress of soil-rock TB crack is predicted and stress value is calculated using LSR method,relationship of crack initiation stress,volume dilatation stress and peak stress are analyzed. The mesoscopic structure of RSA has hierarchy and similarity. Fractal geometry theory is a good method to study mesoscopic mechanics characteristics of RSA,which provides theoretical inference to study the mesoscopic structure and mechanical property for RSA.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2015年第S1期3397-3407,共11页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(41227901)
中国科学院战略性先导科技专项B类项目(XDB10030000
XDB10030300)
关键词
土力学
土石混合体
分形理论
开裂应力
LSR法
单轴抗压强度
soil mechanics
rock and soil aggregate(RSA)
fractal theory
crack initiation stress
lateral strain response(LSR) method
uniaxial compressive strength
