雅砻江牙根二级水电站进水口边坡稳定性研究

发布时间：2018-06-12 21:25

本文选题：牙根水电站 + 岩体质量　；参考：《成都理工大学》2014年硕士论文

【摘要】：边坡稳定性问题是水利水电工程建设的主要工程地质问题之一，研究边坡的稳定性对于工程施工地顺利开展与建成后充分发挥工程效应，具有至关重要的意义。本文结合雅砻江牙根二级水电站边坡稳定性研究课题，在大量现场地质调研基础上，分析了电站进水口边坡岩体结构特征，对边坡岩体风化卸荷分带及岩体质量分级进行了研究，，结合边坡出现的变形破坏现象，建立了边坡相应的变形破坏模式。利用刚体极限平衡法与数值模拟方法对边坡开挖过程中的应力和位移特征进行了分析，系统地评价了工程边坡的稳定性，得到如下主要认识。（1）边坡岩体岩性为燕山早期黑云母二长花岗岩，边坡主要发育三组陡倾角结构面与一组缓倾角结构面。三组陡倾角结构面与坡面走向大角度相交，而缓倾角结构面以倾向坡内产出。受岩体结构控制，自然边坡总体变形较弱，整体稳定性较好，变形主要表现为局部沿陡倾角结构面的卸荷拉裂变形，受缓倾角结构面与陡倾角结构面组合的坠落式崩塌，以及上游侧边坡岩体的板裂化倾倒变形。（2）根据岩体风化卸荷特征与岩体结构特征结合RMR与CSMR法对边坡岩体质量进行划分，得出边坡岩体主要为II级岩体，占边坡岩体总量的50%，主要分布在无风化与无卸荷岩体内；III级岩体占边坡岩体总量的30%，主要为弱下风化岩体；IV级岩体占边坡岩体总量的12.8%，主要为卸荷程度较弱的弱上风化岩体；V级岩体占边坡岩体总量的6.6%，主要为强卸荷岩体。（3）工程边坡开挖水平深度在62～85m之间，在2640m高程以下坡比为1:0.3,2640m高程以上坡比为1:0.5。边坡开挖以后不存在大规模的失稳块体，但硐脸边坡由裂隙组合产生的随机块体易发生楔形块体滑移，上游侧边坡局部板裂状岩体易发生倾倒变形，工程边坡的开口部位分布大量V级岩体易产生小规模滑塌破坏。（4）开挖边坡应力、位移场的三维数值模拟结果表明开挖过程中，坡体内部最大主应力在开挖坡脚有一定的应力集中，总体变化不大，最小主应力在开挖边坡顶部呈正值，表示有拉应力出现，从位移矢量图上看，开挖边坡顶部有指向临空方向的位移，验证了边坡顶部V级岩体的变形特征。在第三部开挖后形成的直立坡顶部，出现指向坡外的位移，且在F15断层出露部位岩体位移量增大，说明边坡开挖以后在F15断层与坡面交汇处岩体易发生失稳，在开挖形成的直立坡顶部岩体易发生失稳。通过UDEC数值模拟软件对上游侧边坡开挖前后的位移变形分析可知，边坡在开挖以后坡顶处的板裂化岩体未产生大位移，总体上处于稳定状态，在开挖坡面顶部f29断层与f28断层之间的岩体位移量最大，位移指向临空方向，往里岩体位移逐渐减小，到f25断层以后岩体基本上没有临空方向位移。说明上游侧边坡开挖以后板裂化岩体未立即发生倾倒失稳，但若岩体不采取任何措施长期暴露于坡表，或在地震工况下有失稳的可能。（5）对硐脸边坡陡倾角断层出露部位应采用锚杆支护，对坡面的随机块体应采用随机锚杆支护，对边坡开口部位的V级岩体应使用喷射混凝土结合系统锚杆支护，对上游侧边坡局部的板裂化岩体应采用预应力锚索支护。
[Abstract]:The stability of the slope is one of the main engineering geological problems in the construction of water conservancy and hydropower projects. It is of vital significance to study the stability of the slope for the smooth development and completion of the construction of the project, and it is of great significance to give full play to the engineering effect after the construction of the project. On the basis of the research, the rock mass structure characteristics of the water intake slope of the power station are analyzed. The weathering unloading zone and the quality classification of rock mass are studied. The deformation and failure mode of the slope is established by combining the deformation and failure of the slope. The stress and the numerical simulation method are used to the stress and the stress in the slope excavation process. The displacement characteristics are analyzed, and the stability of the engineering slope is systematically evaluated. The following main understandings are obtained.
(1) the rock rock of the slope is the early Yanshan black mica two feldspar, and the slope mainly develops three sets of steep dip structure surface and a group of slow dip structure surfaces. The three groups of steep dip angles intersect with the slope to the large angle, while the gentle dip structure surface is produced in the inclined slope. The rock structure is controlled by the rock mass structure, the overall deformation of the natural slope is weak and the whole stability is stable. The deformation is mainly manifested in the deformation of the unloading and splitting of the structural surface along the steep dip angle, the falling collapse with the combination of the slow dip angle structure surface and the steep dip structure surface, and the deformation of the plate cracking of the upper side slope rock.
(2) according to the characteristics of rock mass weathering unloading and rock mass structure combined with RMR and CSMR method, the slope rock mass quality is divided, and it is concluded that the slope rock mass is mainly II grade rock mass, accounting for 50% of the total rock mass, mainly distributed in the non weathering and non unloading rock body; the III grade rock mass accounts for 30% of the total rock mass of the slope, mainly for the weak weathered rock mass; IV grade. The rock mass accounts for 12.8% of the total rock mass of the slope, which is mainly the weakly weathered rock mass with weak unloading degree, and the V grade rock mass accounts for 6.6% of the total rock mass of the slope, which is mainly the strong unloading rock.
(3) the horizontal depth of the excavation of the slope is between 62 and 85m, and there is no mass instability block after the slope ratio of the slope of the 2640m elevation is 1:0.32640m elevation above the slope of the slope, but the random block produced by the fracture combination is easily slipping, and the partial rock mass in the upper side slope is prone to dip. Inverted deformation, a large number of V grade rock mass at the opening part of the engineering slope is prone to small-scale collapse.
(4) the three-dimensional numerical simulation of the slope stress and displacement field shows that the maximum principal stress in the slope body has a certain stress concentration at the foot of the excavated slope during the excavation process, and the overall change is not significant. The minimum principal stress is positive at the top of the excavation slope, indicating the emergence of tensile stress. From the displacement vector diagram, the top of the excavation slope points to the side side of the slope. The displacement of the slope at the top of the slope at the top of the slope shows the displacement of the slope at the top of the third part of the slope, and the displacement of the rock position in the exposed part of the F15 fault increases, indicating that the rock mass at the intersection of the F15 fault and the slope is easy to lose stability after the excavation of the slope, and the rock mass at the top of the vertical slope formed by the excavation is found. It is easy to lose stability. Through the analysis of the displacement and deformation of the upper side slope before and after the excavation of the UDEC numerical simulation software, it can be seen that the plate cracking rock mass of the slope at the top of the slope has not produced a large displacement, and in general it is in a stable state. The displacement of the rock mass between the f29 fault and the f28 fault at the top of the slope is the largest, and the displacement points to the direction of the air. The displacement of the rock body gradually decreases, and the rock mass has no immediate displacement after the F25 fault. It shows that the rock mass of the upper side slope does not collapse immediately after the slope excavation, but if the rock mass does not take any measures for long-term exposure to the slope surface or in the earthquake condition, it may be unstable.
(5) bolt support should be adopted for the location of the steep dip fault in the slope of the slope, and random bolt support should be adopted for the random block of the slope. The shotcrete combined system bolt support should be used for the V rock mass in the opening part of the slope, and the prestressed anchor cable should be used in the partial rock mass of the upper side slope.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV223

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