【作者】 姜海波；

【导师】 侍克斌；

【作者基本信息】 新疆农业大学 ， 水利水电工程， 2011， 博士

【摘要】 土石坝是世界上最古老的坝型之一,有着悠久的建造历史。据统计,全世界超过15m的土石坝共有29000余座,仅在中国就有15000余座。土石坝具有对地基要求较宽松,施工简单方便,适应性强,抗震性能良好,工作可靠、寿命长、管理简便等优点,是世界上应用最广的坝型。由于土石坝的筑坝材料绝大部分是当地土料、石料、砂砾料或土石混合料,其渗透系数都较大。因此,土石坝的防渗结构就成为工程设计和施工的重点,土石坝防渗措施的研究也就成为了重要的研究课题之一。土工膜作为一种新型的防渗体,和传统的土石坝防渗体(粘土心墙、混凝土面板、沥青混凝土防渗体等)比较,有其自身的优点。但是随着土工膜的不断推广应用,也出现了一些工程问题。这主要是我们对土工膜的一些工程特性还不是很清楚。为了更加深入地了解土工膜的工程特性,为土工膜的进一步推广应用提供理论依据。本文采用试验研究、数值计算和理论分析三种方法对土石坝坝体、坝基和水库库区土工膜防渗体力学特性和渗透系数进行了研究。试验研究包括两项内容：(1)采用TZY-1型土工合成材料综合测定仪测定了复合土工膜与粗粒料垫层结构面的摩擦角和粘聚力,复合土工膜与干燥的粗粒料、含水率3%、6%和8.5%的粗粒料垫层结构面之间的摩擦角平均值和粘聚力平均值为别为26.7°、15.9kPa；27.59°、16.76kPa；28.87°、23.95kPa；32.32°、26.14kPa;且摩擦角和粘聚力都随粗粒料含水量的增大而增大。(2)采用自行研制的非散粒体材料摩擦角测定仪测定复合土工膜与粗粒料垫层结构面之间的摩擦角,复合土工膜与干燥的、含水量3%、6%和8.5%的粗粒料的摩擦角分别为30.4°、31.5°、32.5°、34.3°。同样可以得到摩擦角随粗粒料含水量的增大而增大的规律。在工程应用中,当采用摩擦角和粘聚力进行计算时,根据粗粒料含水率的不同,摩擦角可以在26.5°-32°之间取值,粘聚力可以在15.9kPa-26.14kPa之间取值；当只采用摩擦角时,可在30.4°-34.3°之间取值。当然摩擦角和粘聚力的取值,需要根据复合土工膜的特性和粗粒料的性质、剪切条件等进行综合考虑,使试验方法尽可能与实际情况相符合。数值计算包括：(1)采用有限差分方法研究复合土工膜心墙土石坝的力学特性。为了探讨复合土工膜在坝体中的应力变形规律,结合新疆呼图壁河复合土工膜心墙堆石坝,采用三维土工格栅单元模拟复合土工膜与坝体结构面的相互作用,讨论了三维土工格栅单元的9大参数,选取其中必要的5大参数进行结构计算,得出了坝体和复合土工膜在施工完建期、蓄水期、蓄水期加8度地震工况下的应力变形规律。计算结果显示,复合土工膜在端部出现了应力集中现象。(2)采用有限元方法研究复合土工膜斜墙土石坝的力学特性。利用第三章的试验结果,选取合适的摩擦系数,采用库仑摩擦(coulomb friction)模型模拟复合土工膜与粗粒料垫层结构面的摩擦特性,然后结合一座复合土工膜防渗斜墙土石坝,采有限元计算方法,分析复合土工膜土石坝这种新型坝型的力学特性和变形规律。(3)采用有限元方法研究土石坝复合土工膜防渗斜墙的抗滑稳定性。在分析复合土工膜防渗体抗滑稳定机理的基础之上,结合实际工程,进行复合土工膜防渗体的抗滑稳定计算。在计算中讨论了渗流计算的三种边界条件,针对复合土工膜斜墙坝这种新型的坝体,给出了符合这种坝型的渗流边界条件,并计算了复合土工膜坝的孔隙水压力,最后分析计算了坝体复合土工膜防渗体的抗滑稳定。从计算结果可以得出,土石坝复合土工膜防渗体斜墙的临界滑动面近似为一个平面,该平面为坝体垫层与复合土工膜上界面的接触面。理论分析包括库区局部土工膜防渗体的抗裂研究和大面积土工膜防渗体的渗漏估算研究。对于库区局部土工膜防渗体的抗裂研究,首先分析了库区局部土工膜防渗体的抗裂机理,将土工膜的撕裂状态分为两种情况：土工膜未被架空状态的撕裂状态和土工膜被架空状态的撕裂状态。分析两种状态下土工膜的受力情况,分别推导出符合两种状态的微分控制方程,同时分析了两种状态下撕裂强度的影响因素,得出了两个最主要的影响因素：土工膜本身的强度和垫层料的特性。两种土工膜抗裂力学模型的提出,有利于工程人员评价库盘土工膜防渗体的抗裂性能。对于大面积土工膜防渗体渗透系数的研究,首先将土工膜防渗体的渗透量分为土工膜的渗透量和渗漏量,并分析了大面积土工膜防渗体的渗透机理,提出了大面积土工膜防渗体渗漏量和渗透系数的计算方法,即利用区域水量平衡原理计算渗漏量,然后采用达西定律计算渗透系数,并结合工程实例,计算了土工膜破损孔洞影响下的土工膜防渗体的渗漏量和渗透系数。由于破损孔洞的影响,土工膜的渗透系数从最初的10-12cm/s～10-13cm/s下降为10-7cm/s～10-8cm/s,相对而言(铺设土工膜防渗体之前库盘的渗透系数为5.41×10-3cm/s～1.16×10-2cm/s),土工膜防渗体大大改善了库盘的渗漏问题。在实际的工程计算中,库盘大面积土工膜防渗体的渗透系数可在10-8cm/s-10-7cm/s之间取值,来计算土工膜防渗体的渗漏量,评价库盘大面积土工膜防渗体的防渗效果。更多还原

【Abstract】 Earth-rock dam is one of the most oldest dam types which is still current in the world, has a long historical source. According to statistics that there are 29000 earth-rockfill dam in the World,15000 earth-rockfill dam in China. Earth-rock dam has many advantages, such as dam body foundation codition is low, its construction process is simple, strong adaptability, the test behaved very well, reliable operation and long life, simple management. To become most widely used dam types which is still current in the world. Because dam Material of earth-rockfill dam is soil material, stone, sandy gravel, or soil-aggregate mixture, its permeability coefficient is relatively great. So anti-seepage of earth-rock dam become the key design of engineering design and engineering construction, the anti-seepage measures of earth-rock dam has been a important research topic.Geomembrane as a new type impervious body, compared with the traditional impervious body of earth-rock dam, impervious body of geomembrane has its own advantages. But with development and wide application of the impervious body of geomembrane, there emerge some engineering problems. This is mainly because it is not clear about engineering characteristics of geomembrane. So it is quite clear to know that engineering characteristics of geomembrane, this paper adopts experimental study, numerical calculation and theoretical analysis, three methods to study engineering characteristics of geomembrane.Experimental study includes two parts. First, friction characteristics between composite geomembrane and structural plane of coarse-grained materials by using of TZY-1 earthwork synthetic material detenninator. Through friction test, the friction angle and cohesion between composite geomembrane and structural plane of dry coarse-grained materials are 26.7°and 15.9kPa; when coarse-grained materials moisture content is 3%, the friction angle is 27.59°, cohesion is 16.76kPa; when coarse-grained materials moisture content is 6%, the friction angle is 28.87°, cohesion is 23.95kPa; when coarse-grained materials moisture content is 8.5%, the friction angle is 32.32°, cohesion is 26.14kPa; Secondly, friction angle between composite geomembrane and structural plane of coarse-grained materials by using of friction angle determinator of unbulk solid material. the friction angle between composite geomembrane and coarse-grained materials of different moisture contents(dry,3%,6%,8.5%). the friction angle is respectively 30.4°,31.5°,32.5°,34.3°. The friction angle is increased with coarse-grained materials of different moisture contents increase.Numerical calculation includes two parts. First, mechanical properties of core earth and rock dams with composite geomembrane by using of finite difference. Combined with practical work, discussed on structure design of core earth and rock dams with composite geomembrane, analysis and calculation the stress and strain of dam body and composite geomembrane in every case, and summarize in variation of the stress and strain of dam body and composite geomembrane. Secondly, mechanical properties and stability against sliding of slope-wall rock dam with composite geomembrane by using of finite element method. Discussed on structure design of slope-wall rock dam with composite geomembrane, calculation the stress and strain of dam body and composite geomembrane, through analysis calculation results, to get variation of the stress and strain of dam body and composite geomembrane. For analysis stability against sliding of slope-wall rock dam with geomembrane, still adopting finite element method. At first analysis stability against sliding mechanism of slope-wall rockfill dam with geomembrane, based on calculation, top interface of impervious body of geomembrane is weak of sliding surface, embodies a kind characteristics of soften interface. The calculation results consistent with experimental study results.Theoretical analysis includes two parts:anti-crack analysis of impervious body of geomembrane in partial of reservoir area, and seepage stability analysis of impervious body of geomembrane in large scale of reservoir area. For anti-crack analysis of impervious body of geomembrane, at first analysis of mechanism of crack resistance and divided into two aspects:mechanism of crack resistance of geomembrane in overhead state and mechanism of crack resistance of geomembrane in not overhead state. Analysis force condition of geomembrane in two aspects, and derived differential control equation of geomembrane in two aspects, at the same time, analysis influence factorst of ear strength.Through experimental study, numerical calculation and theoretical analysis, The change law of stress and strain and constitutive relation of friction between composite geomembrane and structural plane of coarse-grained materials were summarized. To get mechanical properties of core earth and rockfill dams with composite geomembrane and slope-wall rockfill dam with composite geomembrane. To get anti-cracking characteristicsget of impervious body of geomembrane in partial of reservoir area. To get seepage properties of impervious body of geomembrane in large scale of reservoir area. Study on Engineering Properties of impervious body of geomembrane, has established the important theoretical foundation to practical application of geomembrane.For percolation estimate analysis of impervious body of geomembrane in large scale of reservoir area, infiltration capacity of impervious body of geomembrane were divided into infiltration capacity and seepage amount, analysis permeation mechanism of impervious body of geomembrane in large scale of reservoir area. Combined with practical work, accordance with principle of water balance, estimation seepage amount of impervious body of geomembrane in large scale of reservoir area. Accordance with Darcy law, calculation permeability coefficient of impervious body of geomembranes, to get Seepage regulation of impervious body of geomembrane in large scale. Seepage amount of impervious body of geomembrane reduces to 10"7cm/s～10-cm/s from 10-12cm/s～10-13cm/s.更多还原