摘要
目前在工程设计中,仍粗略地将节理岩体近似为各向同性体,在考虑节理对岩体强度的弱化作用时,均根据节理连通率对完整岩石的抗剪强度参数进行折减,因而未能反映岩体的各向异性特性。这对于浅部岩体工程来讲,也许是可以接受的,但随着建井深度的增加,进入深部状态的岩体表现出更强的各向异性特征,岩体的各向异性将不能忽略。将节理各向异性几何分布特征对岩体力学性能的影响通过微面的节理连通率来反映,从莫尔–库仑抗剪条件出发,采用方向分布函数分析方法,曾提出了一个基于二阶连通率组构张量的节理岩体各向异性强度准则。简要论述该各向异性强度准则,根据该准则研究了井筒的弹性稳定问题。研究表明:考虑岩体的各向异性强度对井筒进行钻井灌浆分析时,在给定的泥浆压力下,沿最大地应力方向钻井的安全系数并不一定比沿其他方向钻井的安全系数高。
In present engineering design, rock mass is simply treated as isotropic material and their strength parameters is given by decreasing those of intact rock through joint connectivity, which is introduced to reflect the integrity of rock mass separated by joints. This method may be acceptable for shallow rock engineering. But for deep rock engineering, with the increase of exploit depth, the anisotropic properties of rock mass become stronger and should be considered. In the previous studies, by defining joint connectivity as a scalar valued ODF（orientation distribution function） in microplanes, and based on Mohr-Coulomb failure condition and anisotropic strength criterion for jointed rock mass, a two-order fabric tensor of joint connectivity was proposed.In the study, the anisotropic criterion for jointed rock mass is presented briefly. The elastic stability problems of wellbore are studied according to the anisotropic strength criterion. When the anisotropic strength of rock mass is considered, the analysis show that drilling along the maximum in-situ stress may not be always safer than that along other direction at a given mud pressure.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2005年第16期2882-2888,共7页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金重大资助项目(50490270)
国家重点基础研究发展规划(973)项目(2002cb412708)
关键词
岩石力学
节理岩体
各向异性强度准则
莫尔-库仑准则
井壁稳定
rock mechanics
jointed rock masses
anisotropic strength criterion
Mohr-Coulomb criterion
wellbore stability
