| 引用本文: | 赵春风,王有宝,吴悦,费逸,龚昕.考虑不同中主应力影响的柱孔卸荷缩孔效应分析[J].哈尔滨工业大学学报,2020,52(11):63.DOI:10.11918/201903189 |
| ZHAO Chunfeng,WANG Youbao,WU Yue,FEI Yi,GONG Xin.Analysis of cylindrical cavity unloading-contraction under different degrees of intermediate principal stress[J].Journal of Harbin Institute of Technology,2020,52(11):63.DOI:10.11918/201903189 |
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| 考虑不同中主应力影响的柱孔卸荷缩孔效应分析 |
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赵春风1,2,王有宝2,吴悦2,费逸2,龚昕2
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(1.岩土与地下工程教育部重点实验室(同济大学),上海 200092; 2.同济大学 地下建筑与工程系,上海 200092)
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| 摘要: |
| 为得到考虑不同程度中主应力影响的柱孔卸荷缩孔解析解,对柱孔开挖卸荷过程中一定卸荷程度下的缩孔和塑性变形进行量化预测,采用统一强度理论(unified strength theory, UST)并引入卸荷因子和缩孔系数,推导得到无量纲化的柱孔卸荷缩孔近似解.对比不考虑中主应力影响的大应变解,给出中间主应力影响系数对孔周位移和应力的分布以及土体刚度、黏聚力、摩擦角对卸荷缩孔的具体影响,结果表明:中间主应力影响参数b越大,卸荷缩孔效应越小,其本质是b的增大使初始屈服卸荷压力降低,推迟外围峰值环向应力的出现,有助于减小孔周塑性区；b对孔周径向位移和环向应力的影响不可忽略,而孔周径向应力受其影响较小；土体刚度对卸荷缩孔关系的影响很大,刚度越大,中间主应力对卸荷缩孔的影响越小.根据无量纲化的卸荷缩孔解析解,可对某指定卸荷程度的柱孔孔径变化进行更合理的定量预测,用于指导隧道支护和开挖、桩基开挖卸荷后的承载特性以及钻井稳定性分析的具体实践. |
| 关键词: 统一强度理论 柱孔收缩 卸荷 中间主应力 土体刚度 |
| DOI：10.11918/201903189 |
| 分类号:TU375 |
| 文献标识码:A |
| 基金项目:国家自然科学基金(41672265) |
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| Analysis of cylindrical cavity unloading-contraction under different degrees of intermediate principal stress |
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ZHAO Chunfeng1,2,WANG Youbao2,WU Yue2,FEI Yi2,GONG Xin2
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(1.Key Laboratory of Geotechnical and Underground Engineering(Tongji University), Ministry of Education, Shanghai 200092, China; 2.Department of Geotechnical Engineering, Tongji University, Shanghai 200092, China)
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| Abstract: |
| To obtain the analytical solution of cylindrical cavity unloading-contraction problem considering the effect of different degrees of intermediate principal stress, quantitative prediction of contraction and plastic deformation was conducted under a certain degree of unloading during cavity excavation. Based on the unified strength theory and by introducing the unloading factor and contraction coefficient, the dimensionless similarity solution of cylindrical cavity unloading-contraction was derived. Compared with the large strain solution without considering the influence of the intermediate principal stress, the effects of the influence coefficient of intermediate principal stress on the displacement and stress distribution of the borehole, and the effects of soil stiffness, cohesion, and friction angle on unloading-contraction were given. Results show that the larger the intermediate principal stress influence parameter b was, the smaller the borehole unloading-contraction effect was, and the essence was that the increase of b reduced the initial yield unloading pressure, delayed the appearance of the peripheral peak hoop stress, and helped to reduce the borehole wall plastic zone. The influence of b on the radial displacement and hoop stress of the borehole was not negligible, while the radial stress was less affected. Soil stiffness had a great influence on the relation between cavity unloading and contraction that the greater the stiffness was, the smaller the effect of b was. Based on the dimensionless unloading contraction solution of borehole, a more reasonable quantitative prediction of the radius variation of cavity at a specified unloading degree can be performed, which can be used in the practice of tunneling excavation and support, pile bearing capacity analysis after boring unloading, and stability analysis of well drilling. |
| Key words: unified strength theory cavity contraction unloading intermediate principal stress soil stiffness |
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