摘要
西部山区工程建设揭露了众多大型弯曲倾倒变形体,多具有软硬互层结构,水平深度可达300 m。为进一步探明软硬互层反倾边坡的倾倒变形机制,融合离心模型试验与UDEC模拟,研究了此类边坡的破坏模式与影响因素,并通过点对分析,讨论了变形的力学机制。数值模拟时,在岩层内预置随机裂隙,获得了破裂面的演化规律。结果表明:数值模拟与试验的位移曲线及破裂面形态吻合较好,边坡变形可分为起始蠕变阶段、稳态变形阶段和失稳破坏阶段;坡体前部为压剪复合变形,后部则以拉张为主;边坡主破裂面呈弧形,由坡脚快速贯通至坡顶,整体为拉–剪性破裂面;坡体内发育3条破裂面,可作为分界线将变形体分为极强倾倒区、强倾倒区和弱倾倒区;坡脚岩体变形后期压致拉裂,逐渐折断脱离母岩,最终导致变形岩体沿不同的破裂面形成渐进后退式破坏;边坡在倾角与坡角之和大于等于120°时才较易破坏,坡角主要影响破坏难易,倾角则控制变形规模。
Most of the toppling deformations exposed in western China have soft-hard interlayer structures. The maximum depth even reaches 300 m. In order to further explore the toppling mechanism of soft-hard interbedded anaclinal slope, centrifugal model tests and UDEC simulation are combined. The mechanical mechanism of toppling is analyzed through point-to-point relative displacement. Random fissures are preset in rock plates of numerical slopes, and the evolution laws of failure surface are obtained. The results show that the displacement and fracture morphology of numerical model agree well with physical tests. The toppling process of slope can be divided into initial creep stage, steady deformation stage and failure stage. The front part of the slope is compression-shear composite deformation, while the rear part is tension-dominated. The main fracture surface runs through the whole slope rapidly from the slope toe with a curved shape, and is a tension-shear fracture surface. There are three fracture surfaces in the slope, which can be used as borders to divide the toppling slope into extremely strong toppling zone, strong toppling zone and weak toppling zone. At the anaphase of the deformation, the failure mode of slope toe turns into compression cracking, and the toe rocks gradually separate from parent rocks, leading to the progressive retrogressive failure of slope along different fracture surfaces. The slope is more likely to be damaged when the sum of the dip and slope angle is greater than or equal to 120°. The slope angle mainly affects the damage degree, and the dip controls the deformation scale.
作者
黄达
马昊
孟秋杰
宋宜祥
HUANG Da;MA Hao;MENG Qiu-jie;SONG Yi-xiang(College of Geological Engineering and Geomatics,Chang'an University,Xi'an 710054,China;School of Civil Engineering,Chongqing University,Chongqing 400044,China;School of Civil Engineering and Transportation,Hebei University of Technology,Tianjin 300401,China)
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2020年第7期1286-1295,共10页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金面上项目(41672300,41972297)。
关键词
反倾边坡
软硬互层
倾倒变形
离心模型试验
离散元数值模拟
anaclinal slope
soft-hard interbedded structure
toppling deformation
centrifugal model test
DEM