增量加卸荷作用下砂岩破坏与声发射特征研究  

Study on failure and acoustic emission characteristics of sandstone under incremental loading and unloading

作　　者：王俊 于洋[1] 丁佳玮 刁心宏[1] WANG Jun;YU Yang;DING Jiawei;DIAO Xinhong(State Key Laboratory of Performance Monitoring and Security of Rail Transit Infrastructure,East China Jiaotong University,Nanchang 330013,China)

机构地区：[1]华东交通大学轨道交通基础设施性能监测与保障国家重点实验室,江西南昌330013

出　　处：《铁道科学与工程学报》2022年第6期1605-1615,共11页Journal of Railway Science and Engineering

基　　金：国家自然科学基金资助项目(42177156,51969007);江西省杰出青年基金资助项目(20202ACBL214016);江西省教育厅科研项目(GJJ210619)。

摘　　要：在公路隧道的施工和运营阶段,岩体经常会受到反复加卸荷的作用。为探究反复加卸荷作用下软岩的强度劣化趋势及声发射特征规律,通过室内单轴反复加卸荷试验配合声发射监测,研究砂岩在不同反复加卸荷条件下的变形、破坏和声发射特征。结果表明:增量反复加卸荷作用下砂岩的破坏形式与其常规单轴的破坏形式具有关联性,主要以剪切破坏形式为主,破碎程度有所提高。在增加保载作用之后,砂岩破裂面变得圆润光滑;反复加卸荷作用下砂岩强度较单轴抗压强度提高了6.8%,增加保载作用后提高了9%;砂岩在反复加卸荷作用下,其扩容应力无明显变化且仍表现出弹塑型破坏特征。在增加保载作用之后,砂岩的滞后变形特征明显;砂岩在峰值应力水平46%~62%之间Kaiser效应明显,在70%以后Felicity效应明显,且FR能较好地量化岩石损伤演化的过程。在增量反复加卸荷过程中,随着加载次数的增加,FR呈现出先增大后减小的规律。根据FR突然降低时的加载应力,可以判断岩石的裂缝损伤应力所处的范围,可为预警岩石破坏提供应用。研究结果可为实际岩石工程中岩体在受到循环反复加卸荷作用下的长期稳定性的评价提供试验参考和理论依据。During the construction and operation stages of highway tunnels,rock masses are often subjected to repeated loading and unloading.In order to explore the strength degradation trend and acoustic emission characteristics of soft rock under repeated loading and unloading,the laboratory uniaxial repeated loading and unloading tests were combined with acoustic emission monitoring to study the deformation,failure and acoustic emission characteristics of sandstone under different repeated loading and unloading conditions.The results show that the failure mode of sandstone under incremental repeated loading and unloading is related to its conventional uniaxial failure mode,mainly in shear failure mode,and the degree of fragmentation is improved.After increasing the load-holding effect,the fractured surface of the sandstone becomes round and smooth;the strength of the sandstone under repeated loading and unloading increases by 6.8% as compared to the uniaxial compressive strength,and it increases by 9% after increasing the load-holding effect.Under repeated loading and unloading,the dilatancy stress of sandstone has no obvious change and still exhibits the elastoplastic failure characteristics.After increasing the load-holding effect,the hysteresis deformation characteristics of sandstone are obvious;the Kaiser effect of sandstone is between 46% and 62% of the peak stress level,the Felicity effect is obvious after 70%,and FR can better quantify the process of rock damage evolution.In the process of incremental repeated loading and unloading,as the number of loading increases,FR presents a law of first increasing and then decreasing.According to the loading stress when the FR suddenly decreases,the range of the crack damage stress of the rock can beidentified,which can provide applications for early warning of rock failure.The research results can provide experimental reference and theoretical basis for the evaluation of long-term stability of rock mass under cyclic loading and unloading in actual rock engineering.

关 键 词：公路隧道 反复加卸荷 砂岩 声发射 Felicity效应 

分 类 号：TU45[建筑科学—岩土工程]