考虑层状岩体结构的深基坑开挖力学效应分析

MECHANICS ANALYSIS OF DEEP EXCAVATION CONSIDERING STRATIFIED ROCK MASS STRUCTURE

层状岩体是自然界广泛存在的一种岩体结构,其在沿层面和垂直层面两个方向上的力学性质差异明显,可以归结为横观各向同性介质,由于层面的影响,受力屈服后的破坏模式也有别于均质岩体。基于横观各向同性弹塑性模型,对计算需要的各向异性面两个相互垂直方向的弹性常量、岩块和层面抗剪强度参数、岩块和层面抗拉强度等参数分别作了多组试验,得出了基本的物理力学指标。基于FLAC3D软件平台,对贵阳某层状岩体深基坑的开挖进行力学计算,分析了4个侧壁的应力状态、位移大小及破坏区分布。结果表明：近似顺倾向的边坡变形大于近似逆倾向及切向边坡,以层面滑移破坏为主,应力释放更明显,说明顺倾向、缓倾角的层状岩体结构对边坡的稳定程度起控制作用。

Stratified rock is a widely existing rock-structure in nature. There are different mechanical properties in both horizontal and vertical directions,which can be attributed to transversely isotropic medium. After yielding,the failure mode is different from homogeneous rock mass. Based on transversely isotropic elastoplastic model,multiple sets of tests were conducted,including elastic constants,shear strength parameters,tensile strength parameters,to obtain the basic physical and mechanical index. Using FLAC3 D software,the mechanical calculation of a deep excavation in stratified rock was carried out in Guiyang. The stress state of the four excavation slope,the magnitude of displacement and the plastic zone distributions were compared. The results showed that the slope displacement of approximate consequent slope was much larger than that of approximate inverse slope and tangential slope. The failure mode was bedding-slip failure,where the stress release was more obvious. The bedding and gentle dip angle of stratified rock mass had played a controlling role in slope stability.