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工程科学与技术:2021,53(2):54-65
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地应力张量特征对地下洞室轴线方位优化的启示
(长江科学院 水利部岩土力学与工程重点实验室,湖北 武汉 430010)
Implications of Geo-stress Tensor Characteristics in Optimizing the Azimuth of Underground Cavern
(Key Lab. of Geotechnical Mechanics and Eng. of the Ministry of Water Resources, Yangtze River Scientific Research Inst., Wuhan 430010, China)
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投稿时间:2019-09-23    修订日期:2020-05-23
中文摘要: 高应力是深埋洞室工程围岩变形和稳定的主控因素,初始地应力对洞室围岩的力学效应主要包括开挖释放荷载和偏应力状态两个方面;地应力与洞室轴线方位的特定组合决定了洞室开挖释放荷载的量值及围岩所承受偏压的程度。为量化既定地应力分布特征下地下洞室长轴线方位的选择区间,推导了一般条件下开挖洞壁面上的法向应力随洞室长轴线与最大主应力夹角的变化规律,并提出极大值和极小值贡献度两个指标,以度量主应力分量对法向应力的贡献。通过研究地应力张量在地下洞室特征平面上的应力椭圆特征随洞室轴线方位变化的方式,获得了围岩所承受偏压程度的变化规律;通过推导获得了地应力张量在水平面内大主应力方位角的解析公式,从理论上证明了当洞室轴线与地应力张量在水平面内的大主应力平行时,地下洞室开挖释放荷载取最小值。结合锦屏一级地下厂房对上述方法进行案例分析,结果表明:当洞室轴线与地应力张量在水平面上的大主应力平行时,开挖释放荷载取最小值;但一般情况下,很难使开挖释放荷载和偏压应力状态同时达到最优。对地下工程围岩稳定的影响而言,地应力是否有利取决于地应力张量的构成特征,因此,应注重对地应力张量空间特征的全面解析。
Abstract:High stress is the controlling factor that influencing the deformation mechanism and stability of surrounding rock mass of deep-seated underground caverns. Stress relief and deviatoric stress state are the main mechanical effects induced due to excavation in rock masses where in situ stress exists. Tensorial nature of in situ stress and the intersection angle between longitudinal direction and major stress determine the magnitude of stress relief and the anisotropic level of induced stress. A general formula was derived for the magnitude of stress relief due to excavation. Thus, the variation law of the magnitude of stress relief was studied as intersection angle between the cavern axis azimuth and maximum principal stress direction varies. An index called “contribution degree” was purposed to quantify the contributions of different principal stress components to the magnitude of stress relief by excavation, and then to ascertain the dominant one. In order to study the variation characteristic of deviatoric stress state, the variation of the characteristics of stress ellipses with the intersection angle between cavern axis and maximum principal stress direction were illustrated graphically in combination with quantitative data. The method has been applied to the underground powerhouse of Jinping fist stage hydropower station. The results showed that when the longitudinal axis of underground caverns parallel to the major stress in horizontal plane, the magnitude of stress relief reached minimum. However, minimizing stress relief and deviatoric level at the same time was difficult. The study showed that due to the complexity caused by tensorial nature, in general case, it was the composition characteristics of geostress tensor that determined how and to what extent the geostress would affect the deformation and stability of surrounding rock mass of underground openings. Therefore, attention should be paid to the comprehensive analysis of the spatial characteristics of the geostress tensor.
文章编号:201900922     中图分类号:TU45    文献标志码:
基金项目:国家重点研发计划项目(2018YFC0407002);国家自然科学基金项目(51879014);中央级公益性科研院所基本科研业务费项目(CKSF2019434);云南省重大科技专项计划(202002AF080003)
作者简介:第一作者:卢波(1977-),男,教授级高级工程师,博士.研究方向:计算岩石力学与试验岩石力学.E-mail:lubo_cky@126.com
引用文本:
卢波,张玉峰,邬爱清,董志宏.地应力张量特征对地下洞室轴线方位优化的启示[J].工程科学与技术,2021,53(2):54-65.
LU Bo,ZHANG Yufeng,WU Aiqing,DONG Zhihong.Implications of Geo-stress Tensor Characteristics in Optimizing the Azimuth of Underground Cavern[J].Advanced Engineering Sciences,2021,53(2):54-65.