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山区河道型水库塌岸预测评价方法及防治技术研究

Research of Forecast, Evaluation and Protective Measures of Bank Failure in Mountain Reservoir

【作者】 汤明高

【导师】 许强;

【作者基本信息】 成都理工大学 , 地质工程, 2007, 博士

【副题名】以三峡水库为例

【摘要】 水库蓄建,库区地质环境和水文条件将会发生前所未有的改变。在库水长期作用下,库岸必将会以各种各样的形式加速其地质历史演化过程——发生塌岸。山区河道型水库往往跨越不同地貌单元,岸坡结构类型复杂,库水动力作用强烈,塌岸模式多种多样,塌岸点多面广,危害十分严重。针对这些特点,选择长江三峡水库为研究背景,以雅砻江二滩水库、白龙江宝珠寺水库、大渡河龚咀水库为类比水库,通过调查、试验和分析等多种手段,对山区河道型水库塌岸机理、模式和参数,塌岸预测方法,塌岸危险度评价和防治措施四个方面的内容进行了系统地研究:(1)通过大量现场塌岸调查,查明了山区河道型水库塌岸分布规律及其影响因素,尤其是第四系岸坡的变形破坏规律。在此基础上建立了各种类型塌岸的室内物理模型,包括多因素模型、单因素模型、结构模型和实体模型,通过室内模拟试验再现了不同影响因素下不同岸坡结构时的塌岸变形破坏方式和演化过程,同时揭示了塌岸土体流失量和塌岸宽度与岸坡组成、坡角、水位变幅、降雨等因素之间的定量关系。(2)建立了山区河道型水库岸坡结构和塌岸模式的系统分类体系,并形成了典型塌岸发生-发展-演化结束三个阶段的演化图。在大量塌岸预测参数调查分析的基础上,改进提出了两种获取塌岸预测参数的方法(横向类比调查和纵向类比调查),分类统计了三峡水库和类比水库区各类岩土的塌岸预测参数(水下堆积坡角、冲磨蚀坡角和水上稳定坡角),同时归纳总结了塌岸预测参数的影响因素及其影响规律。在其它同类水库塌岸预测时,这一分类统计结果具有较强的参考价值。(3)预测实践得出:针对某种类型塌岸,采用适宜该类塌岸的预测模型去进行塌岸范围预测才能得出比较科学合理的预测结果。基于这一研究思路和方向,提出了三种塌岸预测新方法:岸坡结构法、三段法和多元回归分析法;改进形成了滑移型塌岸预测方法、崩塌型塌岸预测方法和流土型塌岸预测方法。并且将各种预测方法有机集成形成了山区河道型水库塌岸综合预测方法体系,包括预测原则、预测方法和模型、预测流程和步骤等。并采用实例预测、类比水库塌岸调查和遥感监测进行了验证。同时对塌岸随时间的发展演化规律进行了初步地分析研究。(4)首次开展了危险度评价在塌岸灾害方面的应用研究,包括山区河道型水库塌岸危险度评价指标体系的构建和量化,塌岸危险度分级,塌岸危险度评价模型和方法的建立,及其应用实例。(5)总结分析了现有各种类型塌岸治理工程(护岸)措施,详细论述了近期发展起来的各种新技术、新方法和新材料,改进提出了一种护岸措施——格构+点砌石护岸。针对山区河道型水库区各种类型塌岸模式及其机理,提出了山区河道型水库塌岸的防治对策。(6)最后采用以上预测评价方法体系,进行了三峡库区塌岸预测与评价。

【Abstract】 The environgeologic and hydrogeologic conditions in riverbank will be greatlychanged when building reservoirs. The raise of waterlevel in reservoir reduces thestability of bank highly. It happens to all kinds of bank failures after building reservoir,especially in mountain reservoirs which commonly crosses many differentphysiognomies and there are all kinds of geologic structures. So it is very dangerous.This paper researches bank failure and its genetic mechanism, develop several newmethods of forecasting bank failure zone, evaluate the dangerous degree of bankfailure, and put forward bank protection measures. We investigate four typicalmountain reservoirs; do a series of physics model tests and works. The major creativeoutcome has been obtained as follows:(1) Base on a lot of field investigations, the characteristics of distribution anddeformation about bank failures is found, especially in Quaternary bank. In order toresearch the genetic mechanism of bank failure, we build four types lab physicsmodels of reservoir bank, including the model considering several factors and singlefactor, the model of soil bank and rock bank, and a model of actual reservoir bankzoom out. Simulate the happening course of bank failure, obtain a lot of data, andobserve some valuable phenomena. After analysis, some quantization relationship isgot between zone or amount of bank failure and angle of bank, bank composition orwaterlevel of reservoir.(2) And the types of bank failure of reservoir are systematically classified for thefirst time. And its genetic mechanism and damage course of each type of bank failuresis analyzed, including happen-develop-end. Then bring forward the common geologiccondition causing each type of bank failure. After field investigations and analysis onThree Gorges Reservoir and other three reservoirs (Ertan, Baozhusi and Gongzui),two ways to get forecasting parameters are brought forward, longitudinal analogism and horizontal analogism. This paper discusses these parameters of bank failureforecasting and its eigenvalue angles (θ,α,β), and takes statistic of parametersabout all kinds of soil and soft rock. After analysis, some regularity conclusions aredrew between the parameters and soil composes and its genesis mechanics orreservoir water dynamical conditions. If the structure of soil is closer, percentagecomposition of coarse grain is greater, or dynamic force of reservoir water is lower,then the eigenvalue angle of forecasting parameters is bigger.(3) The forecast and field practice let author to understand there is a reasonableway to forecast the zone of bank failure. The way is one means to one type of bankfailure. Then forecasting means to each type of bank failures is excogitated one byone, including Reservoir Bank Structure Method (RBSM), Three Segment ForecastMethod, a Multianalysis Regress Method that is developed by means of those physicsmodels tests, a zone-forecasting method of slope-type bank failure, a zone-forecastingmethod of rock sliding type bank failure, and a zone-forecasting method of flowingsoil type bank failure. Then integrate them to form a method system to forecast alltypes of bank failure. Assembly line works together. And design its rule, flow chart,and use step, as like a manual. Author use this integrated method system to forecastthe failure zone of many segment riverbanks in Three Gorges, Ertan, Baozhusi andGongzui Reservoir. The forecasting zone is reasonable and it is verified by fieldinvestigation and remote sensing image.(4) The evaluation to dangerous degree of bank failure is done in this paperfirstly. Include building a factor index system, choosing key factors, deciding impactintensity, building a model and means to calculate total impact value, etc. Thenevaluate three segments riverbank in Three Gorges Reservoir and the evaluationresults accord with our field investigation.(5) After summarizing all kinds of bank protection measures, including newprotection means, new technique and new protective material, and advance a type ofprotective measure. Then bring forward a suitable protection means to each type ofbank failures in mountain reservoir.(6) At last, main and important riverbanks in Three Gorges Reservoir areforecasted and evaluated by using this set of theory and method in this paper.

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