摘要
塑流–拉裂式崩塌或软弱基座型崩塌是我国西南山区和三峡库区常见的一种崩塌类型。当危岩体的下部有较厚的软弱岩层时,此类崩塌发生尤为频繁。软弱岩层在上部岩体压力作用、遇水软化、长期风化剥落等因素作用下,不断压缩并向临空方向塑性流动,导致上覆较坚硬岩层拉裂形成塑流–拉裂式危岩体。离散元模拟得到此类崩塌的变形破坏地质过程为:软岩风化剥落→上部硬岩局部坠落→软弱基座挤出变形→上部硬岩产生下宽上窄拉裂缝→变形继续发展→崩塌产生。根据软弱层不均匀变形前后上部被拉裂硬岩的2种不同破坏模式,应用地质力学分析方法,推导塑流–拉裂式崩塌稳定系数计算公式。以三峡地区万州某边坡为例,采用抗压强度–压应力比值分析法和软弱层不均匀变形稳定性分析法进行对比分析。结果表明:静力条件下,危岩体短期内处于稳定状态;高地震烈度条件下,危岩体不稳定。
The plastic-flow and tensile crack-type collapse or soft foundation-type collapse are very common in Southwest mountain region and Three Gorges reservoir area in China. These types of collapse occur frequently when weak layer distributes under the perilous rock mass. Suffering from the influence of gravity, water softening, long-term weathering and spalling, the weak layer will generate horizontal plastic flow towards free face. Meanwhile, the hard rock will generate tensile cracks. At last, perilous rock mass will generate uneven deformation in a weak layer. The deformation and failure processes of numerical simulation by discrete element method（DEM） are mudstone weathering and sheet-like peeling, hard rock falling, weak pedestal squeezing out, tension crack opening, deformation increasing and collapse occurring. According to two different failure modes of perilous rock mass caused by inhomogeneous deformation of weak layer, the computing formula of stability coefficient of plastic flow and tensile crack-type collapse is deduced by means of the method of geomechanics. Taking a typical rock slope in Wanzhou area of the Three Gorges area for example, the serious contrast and analysis of ratio of compressive strength to compressive stress and stability analysis of inhomogeneous deformation of weak layer are conducted. The results show that under static condition, the perilous rock mass is stable in a short term, on the contrary, it is unstable under high seismic intensity conditions.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2013年第A01期2863-2869,共7页
Chinese Journal of Rock Mechanics and Engineering
基金
中国博士后科学基金(20090450565)
交通部西部交通建设科技项目(200831822353)
关键词
边坡工程
软弱层
离散元
破坏过程
崩塌
稳定系数
slope engineering
weak layer
discrete element
failure process
collapse
safety factor
