摘要
岩体的各向异性特征不仅与结构面的性质有关,还与岩体所处的应力状态紧密相联。基于岩体结构面参数统计,结合应变能推导层状结构岩体本构关系,能够直接确定岩体弹性模量等变形参数。引入各向异性指数的概念,定量地描述岩体变形的各向异性特征。在该基础上,结合某高速公路工程实例探讨岩体结构特征及应力状态对含单组结构面岩体变形各向异性特征的影响规律。研究结果表明,结构面法向密度增加,岩体弹性模量各向异性弱化愈加显著;结构面产状的改变控制岩体弹性模量呈'V'型变化,而岩体变形的各向异性特征不受影响;围压增大可使岩体弹性模量增大,岩体变形的各向异性特征随之逐渐减弱直至完全消失。基于上述结论,解释新建兰-渝铁路碳质板岩隧道中出现的各向异性变形破坏现象,较大的结构面密度与开挖导致围压卸载导致层状围岩弹性模量发生各向异性弱化,是隧道发生各向异性大变形的主要原因。结构面产状决定了弹性模量出现极值的方位,控制掌子面产生局部过大变形的具体位置。
The anisotropic characteristics of rock mass are related not only to the properties of the joints in the rock, but also closely related to the stress state of rock mass. According to the parametric statistics of rock mass, combined with strain energy, a series of constitutive equations of rock mass containing single structural planes is derived to determine the deformation parameters of rock mass, such as elastic modulus. The reliability of the theoretical formula of the deformation parameters is verified by comparison with engineering examples. On this basis, the concept of anisotropic index is developed to quantitatively describe the anisotropic characteristics of rock mass deformation with a single set of joint. An expressway example is introduced to discuss the influence of rock mass structural characteristics and stress state on the anisotropic deformation of rock mass. The research results show that the anisotropy index of deformation increases as well as a significant weakening of elastic modulus with the increase of normal density of the joints. As the change of joint inclinations, the elastic modulus of the rock mass varies with a V-shaped trend, while the anisotropy index of the rock mass deformation will not be affected. In addition, with the increase of confining pressure, the anisotropic feature will weaken until it completely disappears. In regard to the anisotropic deformation and failure phenomenon in carbonaceous slate tunnels of Lan-Yu Railway, the paper finally presents the interpretation in the light of the above conclusions. The intense anisotropic weakening of elastic modulus of rock mass in tunnels was triggered mainly on great discontinuity density and excavation caused unloading of confining pressure. The orientation of minimum modulus is controlled by the occurrence of structural plane, which also determines the position where the local excessive deformation arises in tunnel heading.
作者
李深圳
沙鹏
伍法权
伍劼
LI Shen-zhen;SHA Peng;WU Fa-quan;WU Jie(College of Civil Engineering, Shaoxing University, Shaoxing, Zhejiang 312000, China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2018年第S2期366-373,共8页
Rock and Soil Mechanics
基金
浙江省基础公益研究计划项目(No.LQ18D020001)
中央高校基础科研业务费专项资金(No.310821171125)~~
关键词
层状结构岩体
统计岩体力学
弹性模量
各向异性指数
layered rock mass
statistical mechanics of rock mass
elastic modulus
anisotropy index
