锦屏一级水电站左岸边坡大规模开挖的地质—力学响应研究

发布时间：2018-05-18 14:23

本文选题：高边坡 + 地应力　；参考：《成都理工大学》2014年博士论文

【摘要】：五百米级、数百万方的大规模岩石高边坡开挖及其变形响应是大型水电工程建设面临的重大工程问题。本文通过开挖期的施工地质编录、原位试验等最新工作,详细复核了锦屏一级工程左岸边坡岩体结构特征、岩体质量及参数特征。基于边坡各类结构面的控制作用,分析了边坡变形及稳定的控制性边界条件。全面调查了边坡开挖变形迹象；结合开挖过程和边坡结构,深入分析了不同深度及重点部位的监测数据；总结了本例岩石高边坡研究对象在大规模开挖条件下,其开挖变形的地质-力学响应机制及规律。针对变形主体部位,进行了系统的SIGMA/W开挖模拟分析,探讨了边坡开挖变形基本背景、控制作用及过程,变形性质及稳定性态势。论文取得了以下主要研究成果： (1)工程区所在的断块区域稳定性相对较好,现今构造应力场总体为NW向,属于低围压、低应变能的能量累计状态；而与之相邻的大型活断裂—安宁河断裂—活动性水平较高,其正趋成熟的“地震空区”NW边缘即在坝址区一带,因此应重视其活动性变化将带来的影响。 (2)根据结构面与坡面的交切关系,诠释了结构面迹线侧伏规律,并应用于地质编录,资料校核之中,保障了岩体结构调查的可靠性。通过调查表明：边坡主体部分(坝头及以上)岩体结构条件及质量存在上部偏差、下部相对更好的特征；与前期勘探认识总体一致,但f42-9断层沿线呈现断层密集发育的软弱岩带显然弱化了其主控性作用。 (3)通过开挖期岩体原位试验、波数检测等手段获得的最新成果表明：左岸边坡各级岩体变形及强度参数的初步建议值是合理可信的；为后续的数值模拟分析的参数选取提供了指导性原则。 (4)所揭示的开挖变形响应可归纳为四种性质,即卸荷回弹、差异回弹、倾倒-张裂、深部滑移-张裂等变形破裂现象,以浅表卸荷回弹松弛为主。这些直观的变形迹象主要发育在坡体内部、而坡表不发育,显示变形性质尚属边坡自适应调整态势,并无局部恶化状况。 (5)边坡开挖主体的变形受坡体宏观结构的控制作用明显：多点位移计孔口变形明显者、硐室结构裂纹集中者,都主要集中在坝头拉裂部位；锚索测力计显示的锚固力增加部位,往往也在煌斑岩脉(X)、f42-9断层等主控带的露头附近。 (6)系统监测分析表明,开口线部位的位移矢量大致平行地表、量级100mm左右；开挖区坡体的变形,以水平横河向位移为主导分量,垂向上多以沉降为主,但量值很小,表现出不均匀压缩特征；坡体深部变形主要集中在煌斑岩脉X以内的深裂部位,获得的侧向位移40mm,模拟结果显示垂向上为沉降位变形。总体上,边坡开挖变形动态对开挖过程、进度响应密切,趋面性、波动性、阶段性、节奏性同步特征明显；开挖对上方坡体变形的影响,在100m高差以内强烈,在200-300m以内影响逐渐减弱,以后(尤其挖完后)便趋于稳定。 (7)根据变形现象认识、监测数据反馈和支护工况分析,边坡开挖整体变形的概念模式可总结为一种“岩锚墙底部压缩、上部倾倒鼓胀—深部滑移张裂”的复合模式,进一步的数值模拟分析表明,该模式能够很好地衔接各部位变形现象。 (8)综上可得,锦屏一级左岸岩石高边坡的开挖变形系“大开挖+强支护”条件下受f42-9断层等坝头特定地质结构控制的一种变形自适应调整响应；而导致其深部变形的基本背景在于坡体结构条件和应力调整作用,即f42-9断层本身规模大、控制的范围深,再者就是大规模开挖后应力的强烈分异。三层抗剪洞及系统锚索形成的岩锚墙则是控制开挖变形及稳定的基本作用,实际数据证实,这存在一个“抗剪洞起效→垂向压缩-侧向膨胀→深部扩展”的调和过程。 (9)据上述判断,从控制施工期边坡变形及稳定角度看,实施的支护量是足够的、边坡保持稳定。
[Abstract]:The excavation and deformation response of large scale rock high slope with five hundred meters, large scale rock slope and its deformation response are important engineering problems in the construction of large hydropower project. In this paper, the rock mass structure characteristics, rock mass quality and parameter characteristics of the left bank slope of Jinping first grade project are reviewed in detail through the construction geological cataloging of excavation and the latest work in situ test. In the control of the various structural surfaces of the slope, the control boundary conditions of the slope deformation and stability are analyzed. The evidence of the deformation of the slope is fully investigated. The monitoring data of the different depths and key parts are deeply analyzed with the excavation process and the slope structure, and the large-scale excavation conditions of this rock rock high slope are summarized. At the same time, the geological mechanics response mechanism and laws of the excavation deformation are carried out. According to the main parts of the deformation, the simulation analysis of SIGMA/W excavation is carried out. The basic background, the control and process, the deformation properties and the stability situation of the slope excavation are discussed. The following main research results are obtained.
(1) the fault block area in the engineering area is relatively good, and the present tectonic stress field is generally NW direction, which belongs to low confining pressure and low strain energy accumulative state, and the large active fault adjacent to the Anning River fracture activity level is high, and its mature "ground earthquake space" NW edge is in the dam site area, therefore should be weighed. The impact of its activity changes.
(2) according to the intersecting relationship between the structure surface and the slope surface, the regularity of the side of the structural plane is interpreted and applied to the geological cataloguing and the data checking to ensure the reliability of the investigation of the rock mass structure. The early exploration knowledge is generally consistent, but the weak rock belt with dense faults developed along the f42-9 fault obviously weakened its main controlling role.
(3) the latest results obtained by the excavation in situ test and wave number detection show that the initial suggested values of the deformation and strength parameters of the rock mass at all levels in the left bank slope are reasonable and credible, and provide a guiding principle for the parameters selection of the subsequent numerical simulation analysis.
(4) the excavation deformation response can be summarized as four kinds of properties, that is, unloading springback, difference springback, toppling tensioned and deep slip tensioned crack and other deformation rupture phenomena, which are mainly shallow surface unloading and springback relaxation. These visual deformation signs are mainly developed in the slope body, but the slope surface is not developed, which shows that the deformation property is still the adaptive adjustment state of the slope. There is no local deterioration.
(5) the deformation of the main body of the slope excavation is obviously controlled by the macro structure of the slope body: those with obvious deformation of the multi point displacement meter are mainly concentrated in the part of the crack in the head of the dam, and the anchorage increase part of the anchor cable dynamometer is often near the outcrop of the main control belt, such as the X, f42-9 fault and so on.
(6) the system monitoring analysis shows that the displacement vector of the opening line is approximately parallel to the earth's surface, and the magnitude of the slope is about 100mm. The deformation of the slope in the excavation area is dominated by the horizontal Henghe direction displacement and mainly in the vertical direction, but the quantity is very small, and the deformation is not uniform. The deep slope deformation is mainly concentrated in the depth of the X of the porphyry vein. The lateral displacement 40mm is obtained, and the simulation results show the vertical deformation of the settlement position. In general, the dynamic response of the slope excavation is close to the process of excavation, the characteristics of the surface, the volatility, the stage and the rhythm of the slope are obvious; the influence of the excavation on the deformation of the upper slope is strong within the height of the 100m, and the effect is within 200-300m. Gradually diminished, and later (especially after digging) stabilized.
(7) according to the understanding of the deformation phenomenon, the monitoring data feedback and the support condition analysis, the conceptual model of the whole deformation of the slope excavation can be summed up as a compound model of "the bottom compression of the rock anchor wall, the upper tipping bulging and deep slip tension", and the further numerical simulation shows that the model can well connect the deformation phenomena of various parts.
(8) the excavation deformation of the high rock slope on the left bank of the first grade of Jinping is a kind of adaptive adjustment response controlled by the specific geological structure of the f42-9 fault and other dam head under the condition of "large excavation + strong support", and the basic background of its deep deformation is the structure of the slope and the stress adjustment, that is, the scale of the f42-9 fault itself. The scope of the control is deep, which is the strong differentiation of stress after large-scale excavation. The rock anchor wall formed by three layers of shear holes and system anchorage cables is the basic function to control the deformation and stability of the excavation. The actual data confirm that there is a harmonization process of "shear hole starting effect, vertical compression lateral expansion, deep expansion".
(9) according to the above judgment, from the angle of controlling slope deformation and stability during construction period, the support amount is enough, and the slope is stable.
【学位授予单位】：成都理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TV223

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