高应力下硬岩卸荷破裂:白鹤滩水电站地下厂房玄武岩开裂观测实例分析  

Unloading break of hard rock under high geo-stress condition:inner cracking observation for the basalt in the Baihetan's underground powerhouse

作　　者：江权[1] 樊义林[2] 冯夏庭[1] 李毅[2] 裴书锋[1] 刘国锋[1] 

机构地区：[1]中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室,湖北武汉430071 [2]中国长江三峡工程开发总公司,北京100038

出　　处：《岩石力学与工程学报》2017年第5期1076-1087,共12页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家重点研发计划(2016YFC0600707);国家自然科学基金资助项目(41372315);中科院创新促进会项目(2013215)~~

摘　　要：依托我国目前在建最大的白鹤滩水电站地下厂房面临的高应力诱发围岩破坏问题,通过现场围岩破坏统计调查和岩体钻孔摄像连续观测,全面揭示洞室开挖强卸荷下玄武岩内部破裂的演化全过程。厂房洞室现场围岩表层开裂破坏调查表明:玄武岩卸荷片帮破裂不仅可发生在完整岩体表面,还可发生在含一、二组非充分发育节理的岩体表面,失稳表现形式为片状与板状剥落。进一步的破裂岩片表面细观三维光学扫描和微观电镜扫描分析显示其表面较为粗糙(JRC一般大于8),晶体撕裂无擦痕,揭示了玄武岩片帮的张拉破坏机制。厂房洞室围岩的钻孔摄像连续观察揭示:玄武岩卸荷开裂具有空间非连续性、最大开裂深度逐步增长、裂隙宽度时效增大或减小、锚杆和锚索支护对开裂抑制作用明显等特征。且现场观测还发现,围岩表面的破坏与内部的时效开裂具有协调性,即围岩的开挖损伤区范围内岩体是逐步开裂,当围岩开裂随着时间发展到一定深度且裂缝随时间发展到一定宽度,围岩表层剥落、片帮等破坏行为随即出现。对白鹤滩玄武岩卸荷开裂的观测研究不仅直观揭示了一种高应力下硬岩卸荷破坏的表现形式,还表明监测岩体时效开裂发展过程对于深部硬岩的工程灾害预警和支护优化具有十分重要的意义。The spalling of hard basalt is one of the serious geotechnical problems in the underground powerhouse of the Baihetan hydropower station. The paper presented the general inner cracking process captured by the digital borehole camera and the detailed in-situ failure proofs during the unloading excavation. These study showed that the spalling, with the sheet and plate shape, happened not only to the intact basalt, but to the basalt with a few joints. Further optical scanning and scanning electron microscope observations indicated that the break surface of the spalling rock was rough and belong to the tensional failure mode. The field digital borehole camera observation in the underground powerhouse indicated that the basalt spalling had the characteristics of spatial discontinuous distribution, time-dependent increase of cracking depth, increase and decrease of crack＇s width, obvious restraining effect of rock bolt and anchor cable. What＇s more, the case study also indicated that the inner crack and surface failure of basalt related to each other, namely, the surface failure happened when the inner cracks developed sufficiently. These knowledge about the basalt spalling provided us not only the visual picture of basalt＇s break, but also a guide for disaster warning and supporting optimization in the deep rock engineering.

关 键 词：岩石力学 高应力 卸荷开挖 地下厂房 岩体破裂 钻孔摄像 时效开裂 

分 类 号：TU45[建筑科学—岩土工程]