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

发布时间：2018-01-26 20:32

本文关键词： 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　出处：《岩石力学与工程学报》2017年05期 　论文类型：期刊论文

【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。
[Abstract]:Relying on the high stress induced surrounding rock damage problem in the underground powerhouse of Baihetan Hydropower Station which is under construction in our country at present, the field surrounding rock damage statistical investigation and continuous observation of rock borehole camera are carried out. The whole process of interior fracture evolution of basalt under strong unloading in excavation of cavern is fully revealed. The investigation on the cracking and failure of surrounding rock surface in the site of powerhouse shows that the rupture of the unloading slab of basalt can not only occur on the surface of intact rock mass. It may also occur on the surface of rock mass containing one or two groups of undeveloped joints. Further microscopic optical scanning and microelectronic scanning analysis show that the surface of the fractured rock surface is rough and JRC is generally larger than 8, and there are no scratches in the crystal tear. The mechanism of tensile failure of basalt schist is revealed. The continuous observation of borehole camera shows that the unloading cracking of basalt has spatial discontinuity and the maximum crack depth increases gradually. The crack width increases or decreases, the anchor rod and anchor cable support obviously restrain the crack, and it is found that the failure of the surrounding rock surface is in harmony with the internal aging cracking. In other words, the rock mass is gradually cracked in the range of excavation damage zone of surrounding rock, when the crack of surrounding rock develops to a certain depth with time and the crack develops to a certain width with time, the surface of surrounding rock flakes. The observation and study on the unloading cracking of basalt in Baihetan not only revealed a form of unloading failure of hard rock under high stress. It is also shown that monitoring the development process of aging cracking of rock mass is of great significance for early warning of engineering disasters and optimization of support for deep hard rock.
【作者单位】：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;中国长江三峡工程开发总公司;
【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)~~
【分类号】：TV223
【正文快照】： 随着国家经济、科技和社会的快速融合发展,“上天、下海、入地”已成为当前国际科学研究的前沿主题,我国日益增长的能源、资源和交通刚性需求,必将促使矿山开采、水电开发、隧道建设等进一步向地下深部发展。在金属矿产资源开采方面,狮子山、红透山、夹皮沟、冬瓜山等矿山开采

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