| 卸荷蠕变条件下软硬相接岩层非协调变形规律研究 |
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| 引用本文： | 陈星,李建林,邓华锋,党莉,刘奇,王兴霞,王伟.卸荷蠕变条件下软硬相接岩层非协调变形规律研究[J].岩土力学,2023,44(1):303-316. |
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| 作者姓名： | 陈星 李建林 邓华锋 党莉 刘奇 王兴霞 王伟 |
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| 作者单位： | 1. 三峡大学 三峡库区地质灾害教育部重点实验室，湖北 宜昌 443002；2. 中国长江三峡集团有限公司 流域枢纽运行管理中心，
湖北 宜昌 443133；3. 中国长江电力股份有限公司 葛洲坝电厂，湖北 宜昌 443002 |
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| 基金项目： | 国家自然科学基金资助项目（No. 52009069）；国家自然科学基金高铁联合基金重点项目（No. U203420054）。 |
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| 摘 要： | 软硬相接岩层在长时间跨度内的蠕变变形可能极为不协调，这对开挖工程安全稳定造成严重威胁。对某水电站引水隧洞同一开挖断面内砂质泥岩和泥质砂岩两种软硬相差较大的岩石进行卸荷条件下的蠕变试验和数值模拟，结果表明：在卸围压条件下，试样侧向蠕变变形较轴向发展更为迅速，呈现出显著的侧向扩容；初始围压水平较高时，试样卸荷蠕变破坏的侧向扩容效应更加显著；泥质砂岩在稳态蠕变阶段变形速率比砂质泥岩更慢，蠕变破坏时的应变值均比砂质泥岩蠕变破坏时的应变值要小，征兆性更弱。基于Burgers模型，引入损伤变量，建立带损伤的蠕变本构模型，模型曲线较好地描述了岩石破坏偏应力水平之前的线性蠕变特征和破坏偏应力水平下的非线性加速蠕变特征；软硬相接岩层蠕变数值模拟表明，蠕变变形初期，软硬相接点变形差别幅度不大，随着时间增长，在交接面处发生层间错动，对围岩整体稳定十分不利，工程实践中应予以足够关注。
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| 关 键 词： | 泥质砂岩 砂质泥岩 卸荷 蠕变 力学特性 本构模型 数值模拟 |
| 收稿时间： | 2022-03-09 |
Uncoordinated deformation of soft and hard interconnecting strata under unloading creep conditions |
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| CHEN Xing,LI Jian-lin,DENG Hua-feng,DANG Li,LIU Qi,WANG Xing-xia,WANG Wei.Uncoordinated deformation of soft and hard interconnecting strata under unloading creep conditions[J].Rock and Soil Mechanics,2023,44(1):303-316. |
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| Authors: | CHEN Xing LI Jian-lin DENG Hua-feng DANG Li LIU Qi WANG Xing-xia WANG Wei |
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| Institution: | 1. Key Laboratory of Geological Hazards on Three Gorges Reservoir Area, Ministry of Education, China Three Gorges University, Yichang, Hubei 443002, China; 2. River Basin Complex Administration Center, China Three Gorges Corporation, Yichang, Hubei 443133, China;
3. Gezhouba Power Plant, China Yangtze Power Co., Ltd., Yichang, Hubei 443002, China |
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| Abstract: | The long-term creep deformation of soft and hard rock strata may be very uncoordinated, which poses a great threat to the safety and stability of excavation engineering. A series of creep tests and numerical simulations were carried out on two types of rocks (i.e., sandy mudstones and argillaceous sandstones) with large differences of hardness in the same excavation section of diversion tunnel of a hydropower station under unloading conditions. Results show that under the condition of unloading confining pressure, the lateral creep deformation of the specimen develops more rapidly than the axial deformation and a significant lateral expansion occurs. The specimen under a higher initial confining pressure exhibited a greater lateral expansion effect in the unloading creep failure. The deformation rate of argillaceous sandstone in the steady creep stage was slower than that of the sandy mudstone. Meanwhile, the strain values of argillaceous sandstone in the creep failure were smaller than those of the sandy mudstone with weaker signs. Based on the Burgers model, damage variables were introduced to establish a creep damage constitutive model. The model curve well described the linear creep characteristics of rocks before the failure deviatoric stress level and the nonlinear accelerated creep characteristics under the failure deviatoric stress level. The numerical simulations of creep deformation of soft and hard rock strata show that at the early stage, the deformation difference between soft and hard rock contact points was not large. With the increase of time, interlayer dislocation occurs at the interface, which is very unfavorable to the overall stability of surrounding rock and should deserve sufficient attention in the engineering practice. |
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