深切河谷地应力场分析研究

发布时间：2018-04-03 10:03

本文选题：深切河谷　切入点：地应力场　出处：《长江科学院》2014年硕士论文

【摘要】：中国西部地区属于高地应力、高地震烈度区，正在或即将兴建大量巨型水电站。其坝址区大多处于沟谷深切、构造复杂的区域，为保证在复杂地质和特殊地应力场环境中顺利施工及电站的安全运营，深入开展对深切河谷区地应力场特征研究对于工程选址、具体设计与安全施工具有非常重要的意义。本文针对怒江某水电站坝址区深切河谷应力场问题，，主要开展了下列工作：（1）总结了该水电站的区域构造地质背景和工程地质条件，概括了区域构造地质特征与河谷发育的“分期剥蚀”过程，为河谷应力场演化模拟提供构造应力、侵蚀基准面高程等地质依据。（2）建立了深切河谷应力场的弹塑性有限元模型，其中考虑了三个不同基准面高程的河谷剥蚀过程与多个可能的构造应力场模式。模拟了侵蚀基准面及表层风化对河谷应力场的影响，结果表明影响较小。模拟了不同构造应力模式对河谷应力场的影响，结表明构造应力方向对河谷底部应力集中带及深埋岩体应力的影响较大，对岸坡表层应力的影响较小。（3）根据实测结果，把模拟退火技术(SA)引入到粒子群优化算法（PSO）中进行深切河谷区整场应力研究。通过将包括上述多种构造应力模式的多组构造应力施加到有限元模型上进行正演计算，以构建神经网络训练样本。反演结果和现场实测成果相符，区域构造方位与河流走向呈小角度相交。受地形的影响，右岸边坡岩体应力大于左岸。左右岸边坡岩体最大水平主应力方位随水平埋深的增加而由NE向向NNE向偏转，由与怒江在该段的走向呈大角度相交到趋于平行。河床底部岩体应力集中现象明显，以水平方向应力为主，最大水平主应力方位与怒江该处走向呈大角度相交，随铅直埋深的增加也由与河流走向呈大角度相交向区域构造应力方位过度。
[Abstract]:The western part of China belongs to the area of high ground stress and high seismic intensity, and a large number of giant hydropower stations are being or will be built.Most of the dam site areas are located in deep gully and complicated structures. In order to ensure the smooth construction and safe operation of the power station in the complex geological and special stress field environment, the study on the characteristics of the in-situ stress field in the deep valley region is carried out in depth and the site selection of the project is carried out.The concrete design and the safety construction have the very important significance.Aiming at the problem of deep valley stress field in the dam area of a hydropower station on the Nujiang River, the following work has been carried out in this paper:This paper summarizes the regional tectonic geological background and engineering geological conditions of the hydropower station, summarizes the regional tectonic geological characteristics and the "phased denudation" process of the valley development, and provides tectonic stress for the simulation of the evolution of the valley stress field.Erosion datum elevation and other geological basis.(2) the elastic-plastic finite element model of deep valley stress field is established, in which the erosion process and several possible tectonic stress field models with three different datum elevation are considered.The effect of erosion datum and surface weathering on valley stress field is simulated.The effects of different tectonic stress modes on the valley stress field are simulated. The results show that the direction of tectonic stress has a great effect on the stress concentration zone at the bottom of the valley and the stress of the deep buried rock mass, but has little effect on the surface stress of the bank slope.(3) based on the measured results, simulated annealing technique (SAA) is introduced into PSO (particle swarm optimization algorithm) to study the whole field stress in deep valley.A neural network training sample is constructed by applying multiple sets of tectonic stresses including the above structural stress modes to the finite element model for forward calculation.The inversion results are consistent with the field measurements, and the regional tectonic azimuth intersects with the river strike at a small angle.Due to the influence of topography, the rock mass stress of the right bank slope is greater than that of the left bank.The azimuth of the maximum horizontal principal stress of the left and right bank slope is deflected from NE to NNE with the increase of horizontal burial depth and intersects with the trend of Nujiang River at a large angle to be parallel.The stress concentration of the rock mass at the bottom of the river bed is obvious, mainly in the horizontal direction, and the azimuth of the maximum horizontal principal stress intersects with the strike of the Nujiang River at a large angle.With the increase of vertical buried depth, the azimuth of tectonic stress is excessive from intersecting with the direction of the river to the regional tectonic stress azimuth.
【学位授予单位】：长江科学院
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV221.2

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