| 白垩系红砂岩冻结融化后的力学性质试验研究 |
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| 引用本文： | 刘波,马永君,盛海龙,常雅儒,于俊杰,贾帅龙.白垩系红砂岩冻结融化后的力学性质试验研究[J].岩土力学,2019,40(Z1):161-171. |
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| 作者姓名： | 刘波 马永君 盛海龙 常雅儒 于俊杰 贾帅龙 |
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| 作者单位： | 1. 中国矿业大学（北京） 力学与建筑工程学院，北京 100083；2. 中国矿业大学（北京） 深部岩土力学与地下工程国家重点实验室，北京 100083 |
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| 基金项目： | 国家自然科学基金项目（No.41472259，No.41771083，No.51274209） |
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| 摘 要： | 西部煤矿冻结建井穿越岩层以白垩系、侏罗系等富水弱胶结地层为主，在温度场和地应力场的耦合作用下冻结壁岩体经历了一次完整的冻融过程。以白垩系富水弱胶结红砂岩为研究对象，充分考虑红砂岩冻融过程中受到的温度场与地应力场耦合作用环境，基于力学试验得到白垩系弱胶结红砂岩冻结融化后的力学性质及冻融过程中的地应力对红砂岩力学参数的影响，对白垩系弱胶结红砂岩冻融劣化机理及冻融过程中地应力的影响机制进行了分析。冻融过程中围压分别设置为0、2、4、6、8 MPa，冻结温度分别设置为?5、?10、?15 ℃，融化温度统一设置为20 ℃。试验结果表明，白垩系弱胶结红砂岩胶结差、强度低，对冻融作用非常敏感，仅经历一次冻融后单轴抗压强度即下降28.39 %；冻融过程中的地应力提高了白垩系弱胶结红砂岩孔隙裂隙的约束能力，使冻结作用可以尽可能地向次级微孔隙发展，随着冻结程度的加深，红砂岩内部冻胀力进一步增加，损伤加剧，故而融化后的力学参数相对于无围压冻融进一步降低。研究结果为西部地区煤矿冻结建井井壁设计提供了指导。
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| 关 键 词： | 弱胶结红砂岩 冻融过程 力学性质 地应力 |
| 收稿时间： | 2019-01-08 |
Experiments on mechanical properties of Cretaceous red sandstone after freeze-thaw process |
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| LIU Bo,MA Yong-jun,SHENG Hai-long,CHANG Ya-ru,YU Jun-jie,JIA Shuai-long.Experiments on mechanical properties of Cretaceous red sandstone after freeze-thaw process[J].Rock and Soil Mechanics,2019,40(Z1):161-171. |
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| Authors: | LIU Bo MA Yong-jun SHENG Hai-long CHANG Ya-ru YU Jun-jie JIA Shuai-long |
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| Institution: | 1. School of Mechanics and Civil Engineering, China University of Mining & Technology, Beijing 100083, China;
2. State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining & Technology, Beijing 100083, China |
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| Abstract: | The boreholes in frozen coal mines of western China mainly cut through the Cretaceous and Jurassic rock formations characterized as water-rich and weakly cemented strata. The rock mass in the frozen wall undergoes a complete freeze-thaw process under the coupling effect of temperature field and crustal stress field. In this paper, considering the coupling effect of the temperature field and the geostress field in the process of freezing and thawing, the Cretaceous water-rich and weakly-bonded red sandstone is selected to see its mechanical properties based on experiments. Meanwhile, the deterioration mechanism of Cretaceous weakly cemented red sandstone induced by freeze-thaw process as well as the influence of crustal stress during the freeze-thaw process are analyzed. During freeze-thaw process, the confining pressures are set to be 0, 2, 4, 6, 8 MPa separately, the freezing temperatures are ?5, ?10, ?15 ℃ separately, and the thawing temperature is 20 ℃ for all samples. The results show that the Cretaceous weakly cemented red sandstone is very sensitive to freezing and thawing process because of its very poor cementation and low strength. After only one freeze-thaw cycle, the uniaxial compression strength decreases 28.39%. The crustal stress during the freeze-thaw process enhances the binding forces of pores and cracks of Cretaceous weakly cemented red sandstone, therefore the freezing fully develops to the secondary micro-cracks. Due to the further development of freezing effect, the frozen-heave force in the red sandstone increases, strengthening the damage of red sandstone. Therefore, the mechanical properties of red sandstone after melting are further reduced relative to the non-confined freezing and thawing condition. The experimental results in this paper is helpful for the design of shaft lining of borehole located in the frozen coal mines in western China. |
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| Keywords: | weakly cemented red sandstone freeze-thaw process mechanical properties crustal stress |
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