青藏高原雅江河谷地带碎块石土强度特性及颗粒破碎分析  

Strength characteristics and particle crushing analysis of gravel-block soil in the Yarlung Zangbo River valley of the Qinghai-Tibet Plateau

作　　者：全志 温韬 郭威[1] 贾文君 王熠辉 黄德昕 史雪晴 黄婉滢 QUAN Zhi;WEN Tao;GUO Wei;JIA Wenjun;WANG Yihui;HUANG Dexin;SHI Xueqing;HUANG Wanying(School of Geosciences,Yangtze University,Wuhan 430100,China;Jiacha County Branch of Hubei Yangtze University Technology Development Co.,Ltd.,Shannan 856499,China)

机构地区：[1]长江大学地球科学学院,湖北武汉430100 [2]湖北长大科技开发有限公司加查县分公司,西藏山南856499

出　　处：《铁道科学与工程学报》2024年第9期3647-3660,共14页Journal of Railway Science and Engineering

基　　金：国家自然科学基金资助项目(42477174);西藏自治区科技项目(XZ202301YD0034C,XZ202202YD0007C,ZDZX2024000002)。

摘　　要：碎块石土在西藏等高寒地区广泛分布,其力学性质受粗颗粒含量、干密度及含水率的影响较大,且对评价该区域的堆积层滑坡稳定性十分重要。为探究粗颗粒含量、干密度及含水率对青藏高原雅鲁藏布江河谷地带碎块石土强度和颗粒破碎率等参数的影响规律,开展了4种粗颗粒含量、3种干密度和2种含水工况下的碎块石土大直剪试验,分析了剪切过程中的应力变化规律、剪切后的颗粒破碎率及体变特征。结果表明:当试样干密度为1.4g/cm^(3)时,应力应变曲线在高粗颗粒含量(p_(5)≥40%)下没有出现峰值,试样未发生剪切破坏,随着干密度的增大,试样发生剪切破坏的临界粗颗粒含量和竖向压力不断降低;碎块石土的黏聚力c以p_(5)=20%为临界点,随着粗颗粒含量的增大先减小后增大,内摩擦角φ随p_(5)的增大逐渐变大;碎块石土的颗粒破碎率与粗颗粒含量、竖向压力和初始干密度均呈正相关;粗颗粒含量和干密度的增大均会提高试样的界面抗剪强度,降低试样的最终体变量。试样的剪胀性受碎块石相互咬合形成的骨架结构的强度和竖向压力的影响,当σ=100 kPa,p_(5)≥20%时,试样表现出剪胀特性,随着竖向压力的增大,试样由剪胀向剪缩转变;在饱和含水工况下,碎块石土的抗剪强度降低,最终体变量与剪缩量大幅增加。研究成果可为青藏高原碎块石土滑坡稳定性研究提供指导。Gravel-block soil is widely distributed in high-cold regions such as Tibet,and its mechanical properties are greatly influenced by the coarse particle content,dry density and moisture content.It is of great importance for evaluating the stability of the deposit slopes in this region.To investigate the influence of coarse particle content and dry density on the strength and particle crushing characteristics of gravel-block soil in the Yarlung Zangbo River Valley region of the Qinghai-Tibet Plateau,large direct shear tests were conducted on gravel-block soil under four coarse particle content conditions,three dry density conditions,and two water content conditions.The stress variation during shearing,particle breakage rate,and volumetric deformation characteristics were analyzed.The results are shown as follows.When the dry density of the sample is 1.4 g/cm^(3),the stress-strain curve does not exhibit a peak for high coarse particle content(p_(5)≥40%),indicating that the sample does not experience shear failure.With increasing dry density,the critical coarse particle content and vertical pressure for shear failure of the sample continuously decrease.The cohesion of the gravel-block soil exhibits a critical point at p_(5)=20%,with a decrease followed by an increase as the coarse particle content increases.The internal friction angle gradually increases with an increase in p_(5).The particle breakage rate of the gravel-block soil is positively correlated with the coarse particle content,vertical pressure,and initial dry density.Both increasing coarse particle content and dry density improve the interface shear strength and reduce the final volumetric deformation of the sample.The shear expansion of the sample is influenced by the strength of the interlocking skeleton structure formed by the gravel blocks and the vertical pressure.When σ=100 kPa and p_(5)≥20%,the sample exhibits shear expansion characteristics,which transition to shear contraction with increasing vertical pressure.Under saturated water content co

关 键 词：大直剪试验 粗颗粒含量 抗剪强度指标 颗粒破碎率 剪胀 

分 类 号：TU411.7[建筑科学—岩土工程]