干缩、湿胀作用下黏土岩崩解的FDEM模拟  

Numerical simulation research on the slake of clay rocks caused by drying-shrinkage and wetting-expansion based on FDEM

作　　者：程树范 叶阳 曾亚武[1,3] 高睿[1,3] 彭志雄 CHENG Shufan;YE Yang;ZENG Yawu;GAO Rui;PENG Zhixiong(School of Civil Engineering,Wuhan University,Wuhan,Hubei 430072,China;Faculty of Engineering,China University of Geosciences,Wuhan,Hubei 430074,China;Key Laboratory of Safety for Geotechnical and Structural Engineering of Hubei Province,Wuhan University,Wuhan,Hubei 430072,China)

机构地区：[1]武汉大学土木建筑工程学院,湖北武汉430072 [2]中国地质大学(武汉)工程学院,湖北武汉430074 [3]武汉大学岩土与结构工程安全湖北省重点实验室,湖北武汉430072

出　　处：《岩石力学与工程学报》2023年第8期2068-2080,共13页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(42107175,51178358,12172280)。

摘　　要：黏土岩是常见的工程岩体之一,其遇水后的软化和胀缩变形是诱发滑坡、崩岸等地质灾害的重要内因。为深入理解干缩、湿胀过程中黏土岩力学参数的劣化规律和胀缩裂纹的扩展模式。首先,在湿度应力场理论的基础上,推导基于水头的湿度应力瞬态分析方法,其次,开发一种湿度相关的黏聚力单元(可进行湿度扩散计算,且黏聚力单元参数与湿度相关),并通过实验数据对其主要参数进行标定,最后,基于有限离散元方法(FDEM)对黏土岩受荷膨胀和干湿崩解进行模拟,通过与试验对比,验证本文模拟方法的可靠性。研究表明:(1)黏土岩吸水膨胀过程中,也表现出吸水软化的特点,饱和黏土岩单轴抗压强度和弹性模量仅为干燥试样的22%和25%,在进行岩土膨胀分析时不能忽略力学参数受含水率(湿度)的影响;(2)黏土岩吸水膨胀在时效上滞后于吸水软化,在较大荷载(大于膨胀应力)作用下,侧限状态的黏土岩会出现压缩恢复的现象;(3)干湿过程中胀缩裂纹是诱发黏土岩崩解的主要因素,外侧裂纹易贯通形成碎块,内部裂纹则导致试样出现不可逆损伤。本文提出一种新的岩土体胀缩模拟方法,对于膨胀岩地区的边坡、隧道和库岸的工程计算有一定的指导作用。Clay rock is a common engineering rock mass.Its water-softening and expansion properties are an internal predisposition to geological disasters such as landslides and bank collapses.To understand the water-induced deterioration of mechanical parameters and the propagation of cracks in the process drying-wetting cycles,laboratory test and numerical simulation were carried on.Firstly,a humidity stress transient analysis method based on the water head is proposed.Secondly,a humidity-relative cohesive element was developed.Then,the main parameters are calibrated based on the experimental data.Finally,three loading expansion examples and drying-wetting slake samples of clay rock are simulated by FDEM.The study shows that:(1)the clay rock shows the water-softening property in the process of water-induced expansion.The uniaxial compression strength and elastic modulus of saturated samples are 22%and 25%of dry samples.Therefore,the decrease in strength and rigidity cannot be neglected in the expansive analysis of soft rock.(2)The water-induced expansion of clay rock lags behind the water-softening in history.When the normal pressure is larger than the expansive stress,the confined clay rock always appears in the compression recovery phenomenon.(3)The propagation and coalescence of crack is the main factor inducing slake of clay rock during the drying-wetting cycles.The external crack is easy coalescence and fragment was generated,while the internal crack also causes irreversible damage to the sample.In this study,a new numerical method of shrinkage-expansion analysis is proposed,which plays a guiding role in the engineering calculation in slope,tunnel,and reservoir banks in swelling rock areas.

关 键 词：土力学 湿度应力场 基质吸力 有限–离散元 黏聚力单元 干湿循环 膨胀岩 

分 类 号：TU452[建筑科学—岩土工程]