成层状堆沉积土石混合体的结构量化表征及其应用  

Quantitative Structural Characterization of Layered Depositedand Sedimentary Soil-rock Mixtures and Its Application

作　　者：董辉[1] 彭搏程 邹畅宇 高乾丰 DONG Hui;PENG Bo-cheng;ZOU Chang-yu;GAO Qian-feng(Hunan Key Laboratory of Geomechanics and Engineering Safety,Xiangtan University,Xiangtan 411105,China;School of Traffic&Transportation Engineering,Changsha University of Science&Technology,Changsha 410114,China)

机构地区：[1]湘潭大学岩土力学与工程安全湖南省重点实验室,湖南湘潭411105 [2]长沙理工大学交通运输工程学院,长沙410114

出　　处：《长江科学院院报》2020年第12期112-118,共7页Journal of Changjiang River Scientific Research Institute

基　　金：国家自然科学基金项目(51108397);湖南创新型省份建设专项(2019RS1059);湖南省教育厅项目基金(19A477,18C0090)。

摘　　要：第四纪浅表堆沉积土石混合体广泛分布于地表,从结构特征研究其力学特性是解决日益复杂的岩土工程问题的有效途径之一。目前,土石混合体结构的量化主要从密度、含石量、孔隙比等宏观指标间接描述,而微细观的结构指标存在尺度间关联的技术瓶颈。为了更好地研究土石体堆沉积结构对土石混合体力学行为的影响,针对堆沉积演化的成层状特征,采用标准差量化其块石分布形式,借鉴综合结构势理论,将均匀与不均匀土石混合体三轴剪切试验偏应力的比值定义为结构参量m s,分析该参量随轴向应变ε1、不均匀度s及围压σ3c的变化规律,得到其量化表达式,并引入双屈服面弹塑性本构模型进行修正应用。结果表明:m s的变化规律能够较好地体现成层状结构特征对土石混合体力学行为的影响,且土石混合体综合结构势在应变为5%时接近完全释放,特征值m s(5%)几乎能完全反映结构对力学特性的宏观影响;同时,引入m s后的修正本构模型在偏应力精度方面减小了约28%的平均误差,能够更合理地反映成层状土石混合体的宏观力学特性。Shallow quaternary deposited and sedimentary soil-rock mixtures(SRMs)are widely distributed on the earth.One of the most effective approaches to solve the increasingly complex geotechnical problems is to study the mechanical properties of SRMs from their structural characteristics.At present,the quantification of the structure of SRMs is mainly and indirectly described by macroscopic indicators,such as density,stone content,and void ratio;while the multiscale correlation between microscopic and mesoscopic structural indexes is still a technical bottleneck.To better understand the influence of the structure on the mechanical behavior of SRMs,the layered distribution form of rock blocks created in the deposited and sedimentary evolution was quantified via the standard variance based on the idea of comprehensive structural potential.The structural parameter(m s)was defined as the ratio of the deviator stress of uniform SRMs to that of non-uniform SRMs.The variations of m s with the axial strain(ε1),the non-uniformity(s)and the confining pressure(σ3c)were examined,and the quantitative expression of m s was obtained and incorporated into an elastic-plastic constitutive model with double yield surfaces.The results show that the variation of m s well reflects the influence of the layered structural characteristics on the mechanical behavior of SRMs.The comprehensive structural potential of SRMs is released almost completely as the axial strain reaches 5%,and the feature value(i.e.,m s(5%))reflects the macroscopic influence of structural characteristics on the mechanical behavior of SRMs.Meanwhile,the modified constitutive model with m s improves the accuracy of the deviator stress by about 28%.It proves that the modified constitutive model can reasonably reflect the macroscopic mechanical properties of layered SRMs.

关 键 词：土石混合体 成层状 块石结构特征 结构参量 修正本构模型 

分 类 号：TU43[建筑科学—岩土工程]