【作者】 熊靖辉；

【导师】 任光明；

【作者基本信息】 成都理工大学 ， 地质工程， 2009， 硕士

【摘要】 羊曲水电站下坝址坝基岩体内一定深度发育了大量的拉裂缝,且呈密集分布状,分布范围广泛,在空间上具有一定的宽度与延展性,称之为集中卸荷现象,异于坡体自外而内的正常卸荷现象。羊曲水电站下坝址坝基岩体集中卸荷带内拉裂缝较为发育,张裂明显,岩体多呈拉裂、架空状,加之岩溶、缓倾结构面的影响,岩体多较为破碎,岩体质量明显较集中卸荷带外部差。本文对黄河羊曲水电站勘探资料以及区域地质资料,并进行现场勘察的基础上,进行了大量相关资料的收集,在此基础上对羊曲下坝址集中卸荷带的成因机制以及工程效应进行研究。研究表明:(1)对羊曲水电站区域地质背景资料进行分析同时,对区域内大地构造、构造运动历史、黄河河谷演化历史进行了分析;(2)对羊曲水电站下坝址野狐峡段地形地貌、地层岩性、地质构造、水文地质条件、风化卸荷特征、岩溶发育状况等工程地质条件进行了分析;(3)主要根据现场平硐勘察资料以及相关风化卸荷分带标准,对坝基岩体进行了定性、定量的风化卸荷分带;(4)对集中卸荷带的发育分布特征、拉裂缝的走向性特征、拉裂状况、成因类型、力学机制进行了分析;(5)根据区域地质资料及下坝址工程地质条件,在区域构造历史分析研究的基础上,研究表明其主要是在羊曲特殊区域地质构造条件下,早期构造运动中灰岩地层蓄积地应力的在河谷下切过程中,能量快速释放,卸荷回弹追踪早期陡倾断层、结构面沿缓倾结构面蠕滑拉裂,最终形成集中卸荷带。也就是说,羊曲下坝址集中卸荷带是岩体浅表生改造作用的产物;(6)利用FLAC3D对开挖、坝体载荷作用下进行三维计算分析表明,集中卸荷可能导致塑性破坏区的分布的扩展以及边坡不稳定性的增加,坝肩部位塑性区扩展,可能形成潜在不稳定体,应进行支护和加固处理。更多还原

【Abstract】 The basement rock of the YangQu Hydropower station on The Yellow River was found many high-destiny tension cracks in it, and this phenomenon was a common thing in this canyon. It was have a certain width and tractility in the space of basement rock, so called it concentration unloading. The character which the unloading rock was in the certain horizon depth around is distinguishing form the normal unloading rock with surface unloading. There is large quantity of tension crack with clear width, and the rock has much cracks, and among the rocks was much space, so the rock mass was shatter to pieces and the rock mass quality was not good as the no-concentration-unloading zone.This article was based on the field investigation, and the interrelated date searching, such as the exploration data and the areal geology data of the YangQu Hydropower station on the Yellow River. And then the research which was based on those above on the concentration unloading zone mechanism of the YangQu lower reaches dam site and the interrelated engineering effect. Study maily on these fllow points:(1) Based on analyze of the areal geology data and interrelated date searching, the article was analyze on the areal tectonic geology structure, historical geotectonic, history of the Yellow River, etc.(2) This article was analyzed on the engineering conditions such as topography and physiognomy of Yehu Gorge, the formation lithology, the geological structure, the geohydrologic condition, the weathering and unloading characterizations, the karsts conditions and so on.(3) Based on the experimental tunnel investigation data and interrelated standard, the article was separate the different weathering and unloading zone with the qualitative and quantitative research. (4) Research on the concentration unloading zone development and distribution characterization, and the trend of the tension crack in the zone, the cracking condition, the tension crack cause type of formation, the mechanics of tension crack.(5) According the areal geology data, the engineering condition and the historical regional structure research, it shows that the concentration unloading zone formation factor was mainly a product of the special geological of this area. In the earlier period tectogenesis, the strain energy was to store up in the limestone. The strain energy was release in the cutting valley progress. The unloading effective was on the earlier high steep pitch fault or discontinues, it cause the creep-cracking on the gently dipping structure face, and form the concentration unloading zone at last. In other words, the concentration unloading zone of the dam site of the YangQu powerstation was a product of epigenetic Reformation of Rock Mass.(6) Using the FLAC3D, the article analyzed the stress and strain field of the nature condition, the excavation condition and the dam-load condition.Through the analyze of this article, the concentration unloading zone formation was mainly caused by the strong earthquake force, which is the initial factor of the tension crack by the shaking of the fault and fracture face, then the unloading and rebounding effective in the strong gorge vertical process.更多还原