湖南省黄材水库溢洪道滑坡稳定性研究.doc
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1、 湖南省黄材水库溢洪道滑坡稳定性研究摘要:湖南省黄材水库溢洪道滑坡稳定性研究,通过对滑坡特征及其变形破坏机理的探讨,采用刚体极限平衡法对滑坡进行了稳定性分析,经分析研究认为,溢洪道滑坡不稳定,必须加以防治。 关键词:溢洪道 滑坡 稳定性 一、概 述 湖南省黄材水库位于湘江一级支流沩水上游。主坝位于宁乡县黄材镇以西的铁山里,距宁乡县城。是一座以灌溉为主,兼有发电和防洪等综合效益的大()型水利枢纽工程。该工程集雨面积,总库容亿,主坝为黏土心墙坝,最大坝高,坝顶高程,坝顶轴线长。副坝有座,其中竹山坳副坝位于主坝右岸约处,坝型为风化料填
2、筑的均质土坝,最大坝高,坝顶高程,坝顶轴线长。溢洪道布置在竹山坳副坝左岸的狮牛冲,为河岸开敞式,进口为无底坎的宽顶堰,堰顶高程,为控制泄流,其上装扇(宽高)的钢质弧形闸门。 该工程于年月破土兴建,年枢纽工程基本建成,年完成灌区主体工程配套任务,运行至今。工程在灌溉、发电和防洪等方面发挥了巨大效益,对促进当地工农业生产发展起了一定的作用。但由于设计标准太低,主、副坝渗漏严重,因而在年至年的水利“三查三定”中,被列为“七五”期间需进行加固的重点“病险水库”之一。在确定加固方案时,通过整体水工模型试验,认为狮牛冲溢洪道左岸应扩建一孔并改造泄槽。实施过程中,因未做任何勘探工作,对边坡所处的地质环境缺乏
3、认识,扩建开挖时导致边坡先后发生次较大规模滑坡,溢洪道进口滑坡就是其中之一。 该滑坡形成后,设计单位曾对其采取了表层铺盖防渗薄膜、滑体内布设排水洞、前缘设置挡墙等措施,但因缺乏必要的勘探、试验资料,对滑坡特征及其破坏机理认识不足,所以处理尚不彻底。现有观测资料显示,该滑坡仍存在不同程度的变形迹象。为此,必须查明滑坡的边界条件、滑体特征,研究滑坡形成及发展过程和变形破坏机理,并对其在不同工况下稳定状况及其动态变化趋势进行研究分析,以便采取适宜的工程处理措施,确保溢洪道安全运用。 二、滑坡特征及其变形破坏机理 滑坡特征 滑坡所在山坡自然地形表现为上陡、中缓、下陡,其后缘基本处于地形缓陡变坡处,后缘
4、圈椅状特征比较明显,滑壁近于直立,高。前缘向坡外凸出,鼓胀区特征明显,前舌略伸入沟底(靠近原冲沟岸边),最大高差。滑坡顺溢洪道呈长条形分布,长约,宽,滑体厚一般为,纵剖面上为近似圆弧状,呈段弧形折线,体积约。滑体具有前陡后缓的地形特征,下部地形坡度,上部。 滑坡变形破坏机理 滑体物质上部为残坡积物,下部为风化破碎岩块夹劣质煤层、粉质黏土等。基岩中节理裂隙发育,加之岩体抗风化能力弱,严重破坏了岩体的完整性,使得岩体具有层状碎裂结构的特点。滑坡地带地形陡缓不一,岩体性质和岩体结构存在差异,滑坡变形破坏表现为上部(后缘)从残坡积物中拉裂,下部沿强风化破碎岩块与完整基岩接触面滑动。 滑坡变形破坏的力学
5、机理:人工开挖使前缘边坡变陡,加之降雨及地表水渗入,使处于临界稳定状态的岸坡岩体在水的作用下软化、强度降低,发生压缩蠕变,坡体重心外移,并在其他各种因素尤其是开挖切脚的影响下,致使岸坡下滑,形成滑坡。由于基岩风化破碎,其滑面并非完全受控于岩体的结构面,故而形成近似圆弧状的破坏模式。究其原因有二:一是地形地质环境是形成该滑坡的内因。滑坡区地表残坡积层广布,岩土松散,有架空现象,下部基岩为薄厚不一的层状砂质板状页岩,浅变质细砂岩夹炭质板状页岩及劣质煤层,岩体中结构面发育,风化破碎,岸坡岩体卸荷松弛,地形坡度较陡,不利于边坡稳定。二是溢洪道开挖、地表降水入渗以及施工放炮震动等,是促使滑坡产生的外因。
6、众所周知,由于坡脚开挖,减小了阻滑力,破坏了原本稳定性较差的山坡自然平衡状态,而地表降水的入渗,致使边坡岩(土)体力学强度降低,加之开挖放炮震动等因素,导致了滑坡的产生和发展。 三、溢洪道滑坡稳定性研究分析稳定安全系数的计算方法目前水利水电工程的边坡稳定性分析大多采用刚体极限平衡法。本文分别采用摩根斯坦法()、不平衡推力法、简布法()等三种极限平衡的方法计算滑坡的稳定安全系数。计算中考虑的荷载有滑体自重、地下水的静水压力和动水压力。计算剖面与计算参数的选用计算剖面采用、和三个纵剖面(以下简称剖面、),剖面按垂直划分条块,、分别划分为、个条块,条块从上往下编号。计算参数的选取是根据黄材水库溢洪道
7、滑坡室内岩土力学试验成果并结合岩土体在天然状态下的性状综合考虑的。滑体湿容重,饱和容重,抗剪强度参数取为,饱和状态的抗剪强度参数取为,。计算工况根据工程实际运行情况,拟定如下计算工况作为控制工况。工况:钻探试验、取样时,即枯水位。工况:正常蓄水位。工况:设计洪水位。工况:校核洪水位。工况:校核洪水位骤降至正常蓄水位。工况、属基本组合,工况、属特殊组合。计算成果及分析根据摩根斯坦法、不平衡推力法、简布法的基本原理,用稳定分析程序计算得到滑坡稳定安全系数。分析看出,只有剖面在工况时的、以及剖面在工况时的、大于,但小于,其余的稳定安全系数均小于,说明滑坡在各种工况下都处于不稳定状态。稳定敏感性分析以
8、上进行的稳定性计算,将滑面的抗剪强度参数作为常数。这种参数是在现有的边坡工程地质研究深度基础上对滑面抗剪强度的综合概括。但是,抗剪强度参数一般都存在时空变异性。因此,进行抗剪强度参数对滑坡稳定的敏感性分析是必要的。根据岩土力学试验成果,滑坡抗剪强度参数的取值为:(天然状态)(天然状态)水下折减系数为。根据、的范围值,选取滑坡典型剖面(即剖面)作为计算剖面,以及钻探、试验取样时(即1枯水位)作为计算工况,采用程序计算滑坡的稳定安全系数。从敏感性分析的结果看,滑坡稳定性安全系数基本上是随凝聚力和摩擦系数的增大而线性地增大。最小的稳定安全系数为,最大的为,而大部分的稳定安全系数在之间,说明这次钻探、
9、试验取样时滑坡是基本稳定或临界稳定,这与钻探、试验取样时滑坡的实际状态(有微小变形)是相吻合的。因此,滑坡稳定性计算选取抗剪强度参数,(天然状态)和,(饱和状态)是合理的。四、结 语根据湖南省黄材水库溢洪道滑坡特征及其变形破坏机理和滑坡稳定性研究分析,滑坡稳定安全系数为,滑体在各种工况下都是不稳定的。因此,必须采取排水、抗滑桩、挡墙等综合工程处理措施,加固整治滑体,防止变形和滑动,确保副坝和溢洪道安全运行。参考文献: 崔政权,李宁边坡工程:理论与实践最新发展北京:中国水利水电出版社,/Porganization system and working mode, the selection of
10、 a number of municipal strengthening group to build innovation and strengthen the organization of the basic level organizations advanced model.(seven) the manual work of the Communist Youth League Organization published and League branch of manual work, to promote the use of two manuals in the citys
11、 organizations at various levels. The county committee, directly under the group (work) is under the jurisdiction of grassroots League and group (total) using branch ratio shall not be less than 70%.Three, to further strengthen the groups leadership and team building(a) to strengthen the leagues lea
12、dership at all levels of construction. Continue to do a good job of municipal Party Committee Organization Department on the strengthening of the Communist Youth League cadres management opinions implementation. To promote the group counties (autonomous counties, cities) Commission and city directly
13、 under the group (workers) appointed to carry out the Five team building activities. Improve the League Association Department working mechanism. Conscientiously fulfill the duties of CO, combined with the city group directly under (the) Committee of the general election and the adjustment, actively
14、 jointly with the unit where the party organization department good group leadership selection with the work. Do a good job in municipal Party committee assistant committee leadership and leading cadres of the annual assessment work, adhere to and improve the assistant secretary of the Communist You
15、th League talk system group To weave individual conversation and collective conversation, to strengthen the committees of all levels, the Standing Committee of the Standing Committee, the establishment of a sound system of central group learning, the system of investigation and study, the system of
16、important issues and the reporting system.(two) to strengthen the work of education and training of cadres to conscientiously implement the Central Committee. On the implementation of grassroots cadres training project and opinions on carrying out the mission municipal CYL Cadres training project im
17、plementation opinions, full implementation of the project of the City Youth League cadres training education. Focus on the county grassroots cadres and workers focused on training, the new school system vocational training League cadres, for the Municipal Organization Department jointly held the thi
18、rd session of the Communist Youth League system training cadres in party. Focusing on the construction of new socialist countryside, strengthening village cadres and rural construction team group member of the young team, the county organizations at various levels throughout the year is expected to
19、train 100 00 rural grassroots cadres, plans to train 1000 village secretary of the village Party branch.(three) actively promote grassroots cadres election work. Under the unified leadership of the party organization, to strengthen grassroots organizations direct work, standardize the election work
20、rules and procedures, in the designated candidate, open competition to democratically elected branch secretary at the same time, actively and steadily the development of Township, streets and other grassroots organizations in the direct election of the pilot work, on the basis of summarizing the exp
21、erience and gradually expand the scope of the pilot, and gradually formed a set of measures and cadres election system.(four) to strengthen the cadres testing exercise. To study the development of XX city from 2006 to 2008 cadres testing exercise planning. To select outstanding cadres to the central
22、 mission in Beijing, Shanghai, Guangzhou and other central organs and sending work in developed areas. With the Central Committee the implementation of the western region and ethnic minorities cadres training plan . To carry out the eighth batch of municipal organs attachment cadre management, selec
23、tion, training work. The outstanding cadres to start the National Development Bank XX branch testing exercise.(five) to strengthen the group construction. The main position to play the role of Youth League cadre education and training as the city, in accordance with the requirements of post training
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