雅砻江牙根二级水电站右坝肩边坡支护措施研究

发布时间：2018-06-28 09:26

本文选题：右坝肩边坡 + 缓倾结构面　；参考：《成都理工大学》2014年硕士论文

【摘要】：拟建牙根二级水电站是雅砻江中游规划的第三个梯级电站，设计重力坝最大坝高153m，右坝肩边坡开挖高度近210m，最大开挖深度近100m。边坡断裂、裂隙发育，地质条件复杂，尤其是受一组顺坡缓倾小断层及裂隙密集带的控制，边坡变形强烈，浅表岩体松弛拉裂，稳定性较差，工程开挖边坡存在极大的安全隐患。因此，研究右坝肩边坡稳定性，进而提出相应的支护措施建议，对确保工程施工安全具有重要的实际意义。本文在查明边坡赋存的地质环境条件、岩体结构及变形破裂特征基础上，建立边坡变形破坏机制的概念模型，采用地质分析、刚体极限平衡法及数值计算方法综合分析边坡稳定性，进而提出工程边坡初步支护设计方案。取得了以下主要成果。（1）边坡岩性为燕山早期黑云二长花岗岩，以发育NW向顺坡缓倾角结构面为特征，边坡内部发育的fh01、fh02、fh03、fh04、fh05、fh06长大缓倾角断层对边坡的稳定性起控制性作用。此外发育NE向陡倾及NWW-EW向陡倾两组陡倾角结构面。受岩体结构控制，边坡岩体普遍沿缓倾角断层发生蠕滑拉裂变形，最大滑移变形量可达5m以上（PD53平硐f5303）。岩体风化卸荷强烈，强卸荷水平深度可达108m，，弱卸荷最大水平深度可达153m。（2）工程边坡受NW向缓倾角结构面控制，其变形破坏模式为滑移-拉裂型。fh01、fh02、fh03、fh04、fh05、fh06等一系列顺坡缓倾断层作为底滑面，以NNE或NWW向陡倾断层作为后缘拉裂面，横河向陡倾长大断层则构成侧向割裂面。（3）稳定性评价结果表明，右坝肩边坡整体稳定性受控于fh06+f53组合块体，fh01+f53、fh02+f53、fh03+f53、fh04+f53、fh05+f53大型组合块体对边坡的总体稳定性亦存在重大影响。天然工况下fh03+f53、fh04+f53、fh04+f555稳定性系数介于0.865-0.901之间，边坡整体处于不稳定状态。局部以fh03+f53、fh04+f53组合块体稳定性系数最低，介于0.865～0.889之间。fh01+f53、fh02+f53、fh05+f53块体组合稳定性系数介于0.954-1.033之间，边坡整体处于极限平衡状态。暴雨工及地震工况况下，fh01+f53、fh02+f53、fh03+f53、fh04+f53、fh05+f53、fh06+f53组合块体稳定性系数均小于0.95，边坡整体处于不稳定状态。（4）根据稳定性评价结果，对右坝肩边坡不同部位提出了相应的支护措施。边坡加固设计应按照谨慎开挖、减少爆破、分区域分层次支护的原则进行，将工程边坡的整体稳定性控制作为边坡支护措施设计的首要问题，稳定性的控制秉从先整体后局部顺序进行。右坝肩边坡稳定性受典型的控制性缓倾角断层坡体结构控制，工程边坡开挖后，缓倾角断层切出地表，严重影响工程安全性；经边坡下滑力计算结果可知，以缓倾角结构面为底滑面，NNE或NWW向陡倾断层作为后缘拉裂面的组合块体下滑力大，安全系数较低。由于右坝肩边坡内部缓倾角断层性状较差（多为泥型、夹泥型），且延伸长、埋深较大，边坡的支护措施在采用传统的预应力锚索为主对边坡进行加固的同时，还应当采用混凝土抗剪洞置换结构面软弱物质，提高缓倾角断层力学性能，两种有效支护措施结合对边坡整体稳定性进行控制；对于边坡浅表部岩体以及随机不稳定块体采用挂网喷浆及全长黏结砂浆锚杆加强支护，对规模相对较大的潜在不稳定块体主要采用预应力锚索支护。（5）Midas数值计算结果表明，开挖后，坡体表面及坡脚处出现应力调整及应力集中现象，缓倾角断层后缘附近出现较大范围的拉应力区。伴随缓倾角断层切露，断层处出现大水平位移；开挖后缓倾角结构面上部岩体整体均表现出向临空面的滑移变形，剪应变增量区域主要沿缓倾角断层发展。在实施加固措施之后，fh01、fh02、fh03、fh04、fh05、fh06号缓倾角断层附近的最大主应力及最大位移量显著减小，边坡表面应力在支护前后重新变得平滑且连续，指向工程边坡临空面的最大水平位移下降至毫米级别。同时，混凝土抗剪洞的布置中断剪应力增量集中区的贯通，表明工程采用的一系列支护措施对边坡的加固有效，能够较好的防止工程边坡的失稳破坏。
[Abstract]:The proposed two cascade hydropower station is the third cascade hydropower station planned in the middle reaches of the Yalong River. The maximum dam height of the gravity dam is 153m, the height of the right abutment slope is nearly 210m, the maximum excavation depth is near 100m. slope fracture, the cracks are developed and the geological conditions are complex, especially the control of a group of gently sloping small faults and fractured zones, and the slope deformation is strong. The shallow rock mass is relaxed and cracked, and the stability is poor. There is a great safety hazard in the excavation slope. Therefore, it is of great practical significance to study the stability of the right abutment slope and put forward the corresponding support measures to ensure the safety of the construction.
In this paper, on the basis of geological environment conditions, rock mass structure and deformation fracture characteristics, the concept model of slope deformation and failure mechanism is established, and the stability of slope is analyzed synthetically by geological analysis, rigid body limit equilibrium method and numerical calculation method, and then the preliminary support design scheme of Engineering Slope is put forward. The following main points are obtained. Achievements.
(1) the slope lithology is the early Yanshan black cloud two long granite, which is characterized by the development of NW to gentle dip angle structure. The fh01, fh02, fh03, fh04, fh05, and fh06 long dip angle faults in the slope are controlled by the slope stability. In addition, the steep dip and NWW-EW steep dip two steep dip angles are developed. The rock structure is controlled by the rock mass structure. The rock slope rock generally has creeping and splitting deformation along the slow dip fault, the maximum slip deformation can reach more than 5m (PD53 adit f5303). The rock weathering and unloading is strong, the level depth of the strong unloading can reach 108m, the maximum horizontal depth of the weak unloading can reach 153m..
(2) the slope of the engineering slope is controlled by NW to slow dip angle structure surface, and its deformation and failure mode is a series of slippery.Fh01, fh02, fh03, fh04, fh05, fh06 and a series of gentle dip faults as the bottom sliding surface, with NNE or NWW to the steep dip fault as the back edge crack surface, and Henghe to the steep steep fault is a lateral cutting surface.
(3) the stability evaluation results show that the overall stability of the right abutment slope is controlled by the fh06+f53 composite block. The large combination block of fh01+f53, fh02+f53, fh03+f53, fh04+f53 and fh05+f53 also has great influence on the overall stability of the slope. The stability coefficient of fh03+f53, fh04+f53 and fh04+f555 is between 0.865-0.901 and the whole slope of the slope under the natural condition. In the unstable state, the local stability coefficient of fh03+f53, fh04+f53 composite block is the lowest, between 0.865 and 0.889.Fh01+f53, fh02+f53, fh05+f53 block combination stability coefficient is between 0.954-1.033, the whole slope is in the limit equilibrium state. Under heavy rain and earthquake conditions, fh01+f53, fh02+f53, fh03+f53, fh04+f53, fh05+f53, fh06 The stability coefficient of +f53 block is less than 0.95, and the slope is unstable.
(4) according to the results of stability evaluation, the corresponding supporting measures are put forward for different parts of the right abutment slope. The design of slope reinforcement should be carried out according to the prudent excavation, reducing blasting and subregional hierarchical support, and taking the overall stability control of the slope as the primary problem in the design of slope support measures. The stability of the right abutment slope is controlled by the typical controlled gentle dip slope structure. After the excavation of the slope, the surface of the slope is cut out of the surface, which seriously affects the safety of the engineering. The result of the slope sliding force calculation shows that the gentle dip structure surface is a bottom sliding surface, and the NNE or NWW to the steep dip fault as the rear edge pull. The combination block of the split surface has a large sliding force and a lower safety factor. Due to the poor inclination of the slope in the right abutment slope (mostly mud and mud type), and lengthening and burial depth, the supporting measures of the slope are mainly reinforced by the traditional prestressed anchorage cable, while the concrete shear hole replacement structure surface should be adopted. The soft material can improve the mechanical properties of the slow dip fault, and the two effective supporting measures combine to control the overall stability of the slope; for the rock mass and the random unstable block of the slope, the hanging net spray and the full length cohesive mortar bolt are used to strengthen the support, and the prestressing anchor is mainly used for the relatively large potential unstable blocks. Cable support.
(5) the results of Midas numerical calculation show that after the excavation, the stress adjustment and stress concentration appear on the surface of the slope and the foot of the slope, and there is a large tensile stress zone near the back edge of the slow dip fault. With the slow dip angle fault exposure, the large horizontal displacement appears at the fault. After the implementation of the reinforcement measures, the maximum principal stress and maximum displacement of fh01, fh02, fh03, fh04, fh05 and fh06 are significantly reduced, and the surface stress of the slope becomes smooth and continuous before and after the support, pointing to the maximum water level on the surface of the engineering slope. The horizontal displacement is reduced to the millimeter level. At the same time, the concrete shear hole is arranged in the concentrated area of the shear stress increment, which indicates that a series of supporting measures adopted in the project are effective for the slope reinforcement and can better prevent the instability and failure of the 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

【参考文献】