摘要
板裂化严重威胁着深埋井隧施工安全。板裂是否与围岩梯度应力有关目前尚不清楚。在理论证实围岩切向应力梯度随埋深增加的基础上,提出改进的岩石梯度应力营造方法,利用d0(试件上下表面长度差)为0.1~0.8 mm的长方体花岗岩试件,开展梯度应力下岩石变形破坏过程应变监测试验,重点验证梯度应力下岩石能否发生板裂,以及所产生的岩板厚度是否均匀。结果表明:(1)改进的岩石梯度应力营造方法,可在试件端部营造出在厚度方向上线性递变的应力,其变化速率可达10^(3) MPa/m以上。(2)在梯度应力下,在试件端部低应力区域产生了与加载方向一致的拉张应力;该张应力为0.5~1.5 MPa,呈现出“升–降–升–降”的阶段性变化,可通过减小d0予以抑制。(3)在梯度应力下岩石发生了板裂化破坏,所产生的岩板厚度相对均匀;并且板裂化裂纹呈现为拉张的性质,与以往研究结果一致,证实了梯度应力是深部围岩板裂孕育过程不可忽略的重要影响因素。研究结果为进一步研究岩石板裂的发生条件及岩板厚度的影响因素奠定了试验基础。
Rock slabbing is a serious threat to the construction safety of deep buried tunnels. However,it is still unclear whether rock slabbing is related to the gradient stress in surrounding rocks. In this paper,the changes of the tangential stress gradient with the buried depth increase were theoretically analyzed first. An improved method of rock gradient stress construction was proposed. Then,by the method,strain observation tests were conducted on cuboid granite samples with the d0(the length difference of upper and lower surfaces of specimen) between 0.1 and 0.8 mm under gradient stress to confirm whether rock spalling can occur under gradient stress and whether the thickness of formed rock slabs are uniform. The results show that the stress changes linearly along the thickness direction of the specimens,with a rate up to more than 10^(3) MPa/m,which means that the improved method can be used to create gradient stress environment in rocks. It is found that the tensile stress in the low-stress region at the end of the specimen,whose direction is consistent with the loading,occurs in the range of 0.5 to 1.5 MPa under gradient stress. The tensile stress presents a “rise-fall-rise-fall” stage change in the process of loading,and it can be restrained by reducing d0. It is confirmed that rock slabbing occurs under gradient stress,and the formed rock slabs have uniform thickness. Moreover,the formed cracks belong to tension cracks,which is consistent with the previous research results. It is also confirmed that the gradient stress is an important factor that cannot be ignored in the propagation process of deep surrounding rock slabbing. This study lays an experimental foundation for further research on the occurrence conditions of rock slabbing and the influencing factors of the thickness of rock slabs.
作者
高祥
杨科
GAO Xiang;YANG Ke(School of Mining Engineering,Anhui University of Science and Technology,Huainan,Anhui 232000,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2022年第9期1858-1873,共16页
Chinese Journal of Rock Mechanics and Engineering
基金
安徽理工大学校引进人才基金资助项目(13210153)。
关键词
岩石力学
板裂
梯度应力
深部岩石力学
试验方法
岩板厚度
rock mechanics
slabbing
gradient stress
deep rock mechanics
test method
thickness of rock slabs
作者简介
高祥(1990-),男,博士,2013年毕业于防灾科技学院地质学专业,现任讲师,主要从事矿山岩石力学方面的研究工作。E-mail:gaoxiang1606@163.com。
