【作者】 桂蕾；

【导师】 殷坤龙；

【作者基本信息】 中国地质大学 ， 岩土工程， 2014， 博士

【摘要】 滑坡因其具有多发性和频发性的特点,已成为地质灾害中的一个重要灾种,其严重的破坏性,不仅给灾害易发区人民生命及财产安全带来威胁,还对环境、社会、经济造成了诸多不良影响,尤其在过去的三十年,随着人口增长和土地利用扩张,滑坡及其次生灾害(如滑坡涌浪、滑坡坝、堰塞湖等)已造成了大量的人员伤亡和经济损失。我国是世界上受地质灾害影响最严重的国家之一,近五年来,地质灾害以平均每年2万起的规模发生,造成了年均1273人伤亡及失踪,年均直接经济损失达41.43亿元。依据《全国地质灾害通报》中2005年以来的数据统计发现,我国滑坡灾害发生数量占全年总灾害数量的百分比,年均达65%,2006年所占百分比最高,为86%。近期,如2012年《全国地质灾害通报》表明,该年全国共发生地质灾害14322起,造成直接经济损失52.8亿元,其中滑坡灾害发生数量占据总灾害数的76%。长江三峡库区因其复杂的自然条件和地质环境,历来是地质灾害多发区。自2003年6月以来,三峡水库经历了正式蓄水、库水位逐年抬升并达到设计蓄水位的库水位调度过程,在此期间,库区内地质灾害时有发生、隐患点明显增多。据2010年的相关报道显示,库区已知的崩塌滑坡地质灾害隐患点达5386处。目前,虽然随着三峡库区二、三期地质灾害防治项目的完成,已有887处城镇及居民集中区的地质灾害点采取了相应的工程治理措施,但是仍有大量地质灾害隐患点需要依靠人工监测的方式实现灾害防御。因此,鉴于三峡工程重要的政治、经济、社会地位和库区城镇发展的需要,探明该区滑坡发育规律,尤其是探明在库水位调度和大规模城市建设的大环境下,库岸滑坡失稳和古滑坡复活将会带来的灾害风险问题,对保障库区人民生命及财产安全,促进库区城镇发展具有重要意义。重庆市万州区是三峡库区的腹心之地,其特殊的地质环境为滑坡的发育和发生提供了有利条件。鉴于万州区滑坡发育具有分布广、频率大的特点,论文将围绕该区的滑坡灾害问题展开研究和讨论：在探明万州区滑坡发育规律的基础上,基于目前国内外学者普遍接受的风险分析理论和流程,采用理论分析与实例计算相结合的方式,开展了不同尺度的滑坡灾害风险研究。目前,在滑坡发育规律及变形破坏机理研究方面,主要存在的问题包括：如何保障滑坡基础资料的完整性和准确性、如何提高滑坡发育时空预测的可靠性、如何界定滑坡发育特征的时效性、如何统一滑坡变形破坏类型分类标准、如何模拟真实的实验环境以及合理进行数值模拟分析,等。在滑坡灾害风险研究方面,主要存在的问题包括:滑坡风险研究的时间尺度如何界定、滑坡风险研究的空间动态性如何表达、运用传统的破坏概率计算方法如何反应三峡库区中常见的蠕滑型滑坡的局部破坏概率、如何提高风险成果的可信度以及如何加强和完善风险管理工作,等。论文针对目前研究中存在的部分问题,在充分收集和整理万州区滑坡灾害相关资料的基础上,重点在滑坡规模发育规律、区域滑坡易发性分析和单体滑坡局部破坏概率分析方面进行了探讨。通过完成万州区滑坡灾害发育规律分析和不同尺度滑坡灾害风险分析,论文主要取得了以下成果和结论：(1)综合考虑滑坡发育的地质环境条件和滑坡发育的形态规模特征,进行三峡库区万州区滑坡发育规律分析。基于万州区最新和最完整的地质灾害排查资料,进行万州区滑坡灾害的发育规律分析,主要从滑坡发育的地质环境分析和滑坡形态规模尺寸分析两个方面进行。滑坡发育地质环境条件的分析主要包括滑坡的分布高程、地形地貌、水文地质条件、滑坡边界条件和滑坡物质组成及地层年代等；滑坡形态规模分析包括滑坡的平剖面形态和滑坡的尺寸(长、宽、面积、体积)等。通过分析滑坡在上述各项内容中的分布情况,总结万州区已知滑坡的发育特征和规律。(2)基于滑坡发育的规模尺寸,进行三峡库区万州区滑坡发育规模尺寸间的关系分析。根据论文所收集得到的滑坡发育规模尺寸指标(滑坡最大长度、平均宽度、面积和体积)的分布数据,探讨各指标间的关系,主要得出：万州区,无论是涉水型,还是非涉水型滑坡,滑坡发育长度与其宽度的相关性不明显,且通常不发育为在长宽方向上同时具有极大值的滑坡；滑坡发育面积与其长度(宽度)之间具有一定的相关性,滑坡发育面积较大的滑坡,其长度(宽度)也相应发育较大,但随着滑坡发育面积增大,滑坡面积与其长度(宽度)分布图的离散性越明显、相关性越低；滑坡发育体积也满足体积越大,其发育长度和宽度相应较大的特点,但是滑坡体积与滑坡长度(宽度)分布图的离散性更强、相关性较差；滑坡发育体积与面积的相关性相对较好,滑坡体积发育较大时,其发育面积也相应较大,此外,滑坡发育规模增大,滑坡分布数量相应减少,滑坡体积与面积分布图表现出离散性的分布特征、相关性降低。(3)从分析滑坡发生频率密度与规模关系的角度,进行三峡库区万州区滑坡规模发育规律研究。论文将万州区滑坡编录数据分为全区滑坡、涉水型滑坡和非涉水型滑坡三组数据,分别探讨了各组数据中滑坡发生频率密度-规模分布函数方程及拟合曲线。所得结果表明,万州区滑坡发生频率密度-规模分布满足三参数反伽马函数的概率密度分布,并在较大滑坡规模尺寸上满足非累计幂指数函数分布；万州区滑坡规模往往集中发育在一定尺寸范围内,其中非涉水型滑坡在发育规模(宽度、面积、体积)上较涉水型滑坡集中性更强、涉水型滑坡发育为较大规模(宽度、面积、体积)滑坡的可能性更大。此外,通过对比依据不同地区、不同事件诱发下滑坡发生记录得到的滑坡发生频率密度-规模关系分布曲线发现,滑坡发生频率密度-规模关系分布规律具有普适性；滑坡发育受到地质环境和外界因素的控制,其发育规模具有集中于某范围尺寸间分布的特征,滑坡编录数据越完整,滑坡发生频率密度-规模分布曲线越接近基于初始完整滑坡数据所得分布曲线。(4)基于聚类模型,结合万州区地质环境资料、滑坡分布资料,以及滑坡发生频率密度-规模拟合曲线,进行三峡库区万州区滑坡危险性分析。论文首先选择地层年代、高程分布等七个指标作为万州区滑坡易发性分析的评价指标,同时,统计分析已知滑坡在各指标中分布的栅格数据,得到各个评价指标的滑坡易发性等级分布图。其次,基于熵权法和层次分析法的综合评判法,进行万州区滑坡易发性各评价指标的权重计算,得出,地层年代和地形坡度指标对万州区滑坡易发性分析影响最大。再则,选择聚类模型和信息量模型进行万州区滑坡灾害易发性区划,实现了聚类模型算法编写、优化了聚类模型只分类不分级的问题。通过对比两种模型所得滑坡易发性区划结果,信息量模型的区划精度高于聚类模型,但结果过于保守,聚类模型的预测结果更贴近实际情况。最后,结合万州区滑坡分布图和滑坡发生频率密度-规模分布曲线,在进一步修正滑坡易发性区划图的基础上,得到万州区滑坡危险性区划图。总体来看,万州区具有江南区滑坡极高危险区较江北区滑坡极高危险区分布面积广、主城区及长江上游部分地区滑坡极高危险区分布较为集中以及长江下游地区滑坡高危险区呈零星分布的特征。(5)在统计万州全区承灾体及其价值、人口密度分布情况的基础上,进行万州全区滑坡风险分析。万州区承灾体划分为人口、房屋建筑物、交通道路和土地资源四大类。通过分析万州区承灾体易损性,得到：从整体上看,万州主城区的承灾体易损性较大；人口易损性等级分布与滑坡危险性等级分布一致；房屋建筑易损性等级最高的区域集中分布于主城区沿长江、竺溪河交界处的,较高易损性的房屋在滑坡危险性等级为极高的区域内成零星散布；交通道路的易损性等级表现出段状分布的特征,整体上看,交通道路类型级别越高,其抗灾害能力越强,相同等级灾害强度作用下,易损性越小；主城区附近土地资源的易损性等级最高,其余易损性较高的区域与滑坡危险性等级为较高的区域分布基本一致。综合该区经济价值和人口密度分布信息,分析得到万州全区滑坡灾害风险无论是人口风险还是经济风险,主城区的滑坡灾害风险最大。(6)基于加卸载响应比模型,进行三舟溪滑坡地表位移与降雨、库水位响应关系分析。结合三舟溪滑坡GPS地表位移监测资料、降雨及库水位调度资料,运用加卸载响应比模型,探讨了滑坡地表变形与其影响因素之间的响应关系,主要得出：三舟溪滑坡变形加卸载响应比能较好的表征滑坡点的稳定性状况及其变形时段特征；该滑坡处于整体基本稳定、局部欠稳定状态；降雨对该滑坡变形具有促进作用,而与库水位作用比较而言,库水位升降作用对该滑坡的影响更大；从整体上看,三舟溪滑坡在库水作用上表现出中前部先响应变形,中后部后响应变形的牵引式变形特征。(7)基于分形理论中的计盒模型,进行三舟溪滑坡地表位移监测点运动轨迹分形维数计算,进而基于反距离插值法,进行三舟溪滑坡变形分形维数分区。首先,根据三舟溪滑坡地表位移各监测点的GPS监测数据,分析和整理监测点地表位移轨迹曲线；其次,以全年和库水位涨落为计算周期,对各监测点的位移轨迹进行分段；然后,对各监测点分段后的位移轨迹曲线进行图像处理和转换,得到各个运动轨迹分段曲线的灰度图像；再则,利用计盒模型计算各个灰度图像的分形维数；最后,采用反距离插值法(IDW)得到滑坡变形各周期阶段的分形维数分区图。所得分形维数分区图表明：三舟溪滑坡从整体上看在库水位下降期变形较库水位上升期变形严重,从局部上看,滑坡的局部变形受到库水位升降作用的综合影响,不同滑坡部位受库水位升降作用的影响程度不同,在库水位涨落期间,滑坡右侧变形较左侧大、中前部变形较滑坡中后部大。(8)结合GeoStudio滑坡整体破坏概率计算、滑坡变形分形维数分区图、滑坡发育的地质环境特征以及滑坡现场宏观变形调查数据,进行三舟溪滑坡局部破坏概率分析。论文主要运用GeoStudio数值模拟软件中的SEEP/W功能模块,进行在降雨和库水位共同作用下,三舟溪滑坡在不同年不同库水升降调度周期中地下水位的瞬态模拟,进而耦合SLOP/W功能模块计算三舟溪滑坡在不同计算周期中各模拟地下水位线所对应的滑坡整体破坏概率,按照各计算周期中地下水位线模拟结果的合理性和滑坡稳定性系数最小为原则选择表征该计算周期的滑坡整体破坏概率。此外,根据三舟溪滑坡发育的地质环境特征和滑坡现场调查数据,基于滑坡变形分形维数分区图,修正得到实际中滑坡局部变形的边界形态,进而依据滑坡局部变形的严重程度和滑坡整体破坏概率大小及计算剖面线的位置,定性-半定量分析该滑坡的局部破坏概率。所得三舟溪滑坡局部破坏概率分布图表明：三舟溪滑坡局部破坏概率分布图能较好的反应该滑坡在库水位上升和下降两种工况下的局部变形状态；滑坡右侧危险性较左侧大；整体上看,滑坡在库水位下降期间的危险性高于库水位上升期；同时,结合库水位下降和库水位上升两种工况中,滑坡破坏概率较高的区域与地裂缝展布位置的关系,可以推测,滑坡地表直线形、垂直主滑方向排列的裂缝可能是库水位升降综合作用下滑坡局部变形拉裂的结果,而弧形、由垂直主滑方向向平行主滑方向发育的裂缝更可能是库水位下降时期滑坡局部变形拉裂的结果。(9)基于三舟溪滑坡承灾体及其经济价值、人口数量分布资料,进行该滑坡的风险分析。论文按照库水位涨落周期,探讨了三舟溪滑坡的风险,主要考虑的承灾体对象为该滑坡范围内的房屋建筑、室内人口和农田及杂草地。所得不同库水位涨落工况下滑坡风险分析结果表明：从总体上看,三舟溪滑坡库水位下降期滑坡灾害风险高于库水位上升期；对于该滑坡范围内房屋建筑经济价值风险来说,库水位下降期风险总体上高于库水位上升期,在库水位下降期,房屋建筑经济价值风险为0.28至10.1万元,而在库水位上升期,房屋建筑经济价值风险为0.16至2.8万元；对于滑坡范围内室内人口风险来说,部分房屋室内人口风险在库水位下降期高于库水位上升期,在库水位上升期,滑坡范围内室内人口风险共计4人,库水位下降期共计8人；此外,对于其他农用及杂草地的价值风险来说,库水位下降期,滑坡体不同部位土地经济价值风险为933至2160元/亩,库水位上升期,滑坡体不同部位土地经济价值风险为107至933元/亩。更多还原

【Abstract】 As landslides occurred frequently and caused large economical lose and casualties, it has become one of the major geo-hazards. Landslides and the secondary disaster caused by landslides, such as landslide tsunami, landslide dam and lake, etc, have made the situation even worse, especially in the last30years, on account of the expansion of the growth of population and land use. China is one of those countries, affected by geo-hazards seriously, especially by landslides. In the last5years, there were about20,000geo-hazard events occurred in each year by average and made an average annual casualties1273persons and direct economical lose4,143,000,000Yuan. According to the reports of National Geological Disaster Bulletin from2005to2012, the number of landslide events represents about65%of the number of geo-hazard events. The maximal percentage is in2006with86%. Besides, based on the recent report in2012, the number of geo-hazard events in2012is14,322and caused direct economical lose5,280,000,000Yuan. In this year, the number of landslide events took76%of the number of the geo-hazard events.Because of the proper environmental conditions in Three Gorges area, geo-hazards occurred frequently in the history. Since June,2003, the operation of the Three Gorges Dam impoundment has been started, the probability of the occurrence of geo-hazards has increased. According to a report in2010, there were5386landslides had been detected and recorded. And so far, although there were887geo-hazards had been performed prevention and mitigation measures, there are still a large amount of landslides with potential risk. These landslides can only be under manual monitoring. Therefore, on the view of the important political, economical, social status and urban development needs in Three Gorges area, it is meaningful to do research on the development regularities of landslides in this area, and to study on hazard and risk from landslides instability and reactivation by the impoundment of the reservoir water level and the fast urban development. The results would make sense to protect the properties and live, and to promote urban development in this area.Wanzhou district, Chongqing city locates in the middle of the Three Gorges Reservoir area. The proper geological environment conditions provides the formation chances of landslides. Thus, in Wanzhou district, landslides occurred frequently and distributed all around this area. In this thesis, amount of work has been carried out in Wanzhou district and based on the widely acceptable theory in landslide hazard and risk research. For instance, landslides development regularities in this area has been made effort to and landslide hazard and risk research in different scale have been studied on.At present, there are numerous works have been carried out on landslide development regularities, but there are still some difficulties have not been gone through yet, such as:how to confirm the integrity and the accuracy of landslide records, how to increase the reliability of landslide special-temporal prediction results, how to define the timeliness of landslide development characteristics, how to uniform the standard on landslide failure type classification, how to simulate a real environment to a rational simulation analysis on landslides, and so on. Besides, there are also some problems need to be solved on the study of landslide hazards and risk. For instance, how to define the research period when doing landslide risk analysis, how to express the spatial dynamics of landslide hazard and risk, how to represent the partial failure probability of creep landslides when using traditional failure probability calculation methods, how to improve the reliability of landslides risk results, how to strengthen landslide risk management, and so on.In this thesis, some of the above difficulties will be discussed. Based on landslides data collection in Wanzhou district, landsides development regularities, landslide susceptibility in regional scale and landslide failure probability zoning on site scale will be focused on in this thesis. By the end of this study, the results will be given as follows:(1) According to the geological environment conditions and the morphological characteristics of landslides, landslide development regularities will be studied in Wanzhou district. This study is based on the latest investigation records and performed in two main aspects. One is on the view of the geological environment where exist landslides and the other is on the view of the morphological characteristics of those landslides. The analysis on the former aspect includes the characteristics of landslides distribution on different elevation, topography, hydrological conditions, landslides boundary conditions, landslide composition and forming age, and so on. In addition, the analysis on the latter aspects includes landslides morphological characteristics and landslide sizes characteristics, such as landslide maximum length, average width, area and volume. Base on the above landslides characteristics statistics, the landslide development regularities in Wanzhou district is aimed to summarized.(2) Based on the size distribution of landslides in Wanzhou district, the relationship between different landslide size index are planned to be analyzed. The results in this thesis show, in Wanzhou district, both reservoir water connected landslide or unconnected landslides, the correlation between landslide maximum length and landslide average width is not obvious but commonly, few landslide developed with both length and width in very large value. Besides, there is a certain correlation between landslide area and its maximum length or average width. The larger the area of landslide is, the longer or wider the length or width of landslide will be. However, when the value of the area becomes larger, the distribution of landslides becomes discrete and the correlation between landslide area and its maximum length or average width decline. In addition, the correlation between landslide volume and its maximum length or average width is similar to that between correlation between landslide area and its maximum length or average width. Whereas, when the value of the volume becomes larger, the discrete distribution is more obvious and the correlation is also lower than those between landslide area and its maximum length or average width. What’s more, the correlation between landslide volume and area is relatively high. The larger the landslide volume is, the larger the landslide area develops. But, with the increasing of landslide size, the corresponding number of landslides reduce and there shows a discrete distribution and decrease correlation between landslide volume and area.(3) From the perspective of landslide frequency density-magnitude distribution, landslide size development regularities has been analyzed. Landslides data in this thesis has been cataloged into three groups, there are group one with total landslide in Wanzhou district, group two with reservoir connected landslides in Wanzhou district and group three with reservoir unconnected landslides in Wanzhou district. The landslide frequency density-magnitude distribution function and curve will be fitted. The results demonstrate, the three-parameter inverse gamma density distribution function fits the landslide frequency density-size distribution well, as well as the noncumulative exponential distribution function fits landslide frequency density-size distribution on large size. Additionally, the size (such as width, area and volume) of landslides in Wanzhou district tend to concentrated in a certain size range, especially of the reservoir unconnected landslides. This regularity proves that for those landslides connect with reservoir are more likely to develop in larger size (such as width, area and volume). Besides, by comparing the landslide frequency density distribution regularity in different places and triggered by different events, it proved that, this kind of landslide distribute regularity is universal. The formation of landslides are controlled by geological environmental conditions and the external factors, and landslides develop concentrated in a certain size range, the more complete the landslide data is the closer the landslide frequency density-size distribution curve will be fitted to the initial distribution of completed landslide inventory data.(4) Based on clustering model and combined with geological environment data, landslide distribution and landslides frequency density-magnitude fitting curve, landslide hazard analysis will be studied in Wanzhou district. Firstly, there are7indicators, including strata age, elevation distribution and so on, are chosen to perform landslide susceptibility analysis. In this thesis, landslide susceptibility is based on the location of those landslides in Wanzhou district, with raster data statistics, the indicators landslide susceptibility rating map will be get in this step. Secondly, based on the combination of entropy weight method and AHP method, the weight of each indicator will be calculated. In this thesis, the results show that, the weight of strata age and terrain slope are higher than other indicators for landslide susceptibility. Thirdly, cluster model and information model are used to zone landslide susceptibility map in Wanzhou district. This step implements cluster model algorithm programming and optimizing. The result demonstrates although the accuracy of information model is higher than cluster model, the result from information model is too conservative and the result from cluster model is more closer to the actual situation. In the end, combined with landslides distribution map and landslides frequency density-magnitude fitting curve in this area, landslide susceptibility map will be modified and then the landslide hazard map will be get. Over all, the results show the zones with higher hazard rate in the southern part of the river in Wanzhou district distribute wider than the northern part of the river, the zones with higher hazard rate distribute concentrate in the main city and along the upper part of the river bank while along the downstream section of the river, the zones with higher hazard rate distribute scatteredly.(5) By analyzing the distribution of the elements at risk in Wanzhou district, landslide risk zoning will be carried out in this area. In this thesis, the elements at risk include4categories, there are population density, buildings, traffic lines and land resources. The landslide vulnerability zoning result demonstrates, the vulnerability of elements at risk is generally high in the main city of Wanzhou district. Vulnerability distribution of the population is consistent with hazard distribution of landslides. The highest vulnerability distribution of the buildings are concentrated along the junction of Yangtze river and Zhuxi river in the main city and the rest higher vulnerability distribution of the buildings locate on the area with high hazard grade and spread sporadically. The vulnerability of road traffic lines shows the characteristic of section shape distribution. The higher the use level of the traffic lines type, the higher the resilience of the traffic lines should be and under the same intensity of hazard, the smaller the vulnerability of the traffic lines will get. The maximum vulnerability of land resources locate around the main city, and the other higher vulnerability zones generally consistent with hazard distribution of landslides. Besides, based on the analysis of the economic distribution and population density distribution in Wanzhou district, landslide risk zoning map has been gained. The result shows, whether the economical risk or population risk of landslide, the maximum risk value locates around the main city in Wanzhou district.(6) Based on LURR model to analyze the response relationship between landslide displacement and the triggering factors, such as rainfall and the water level of reservoir. Combined with GPS surface displacement monitoring data of San Zhouxi landslide, rainfall records and the water level scheduling information, the responding relationship between deformation of landslides and triggering factors is aimed to be found out. The results in this thesis show, LURR model works well in this analysis and the load/unload response ratio can well represent landslide stability and the characteristics of landslide deformation in different time period. The whole San Zhouxi landslide is stable, but some parts of it are less stable. Rainfall makes contribute to the deformation of San Zhouxi landslide, but the changes of the reservoir water level influences the deformation of this landslide more than rainfall and generally, the front part of this landslide responds first to the changes of the reservoir water level and upper part of this landslide responds later, this shows the traction deformation characteristics of San Zhouxi landslide.(7) Based on the fractal theory and using box-counting method, the fractal dimension of the moving traces of landslide surface monitoring points have been calculated. After that, based on IDW method, the fractal dimension zoning map of San Zhouxi landslide are obtained. Details are, firstly, according to San Zhouxi landslide GPS monitoring data, the moving traces of these monitoring points are analyzed and made as trajectory curves. Secondly, divided the trajectory curves by two ways, one way is by annually, the other way is by the water impoundment cycles. Thirdly, to process and convert the displacement trajectory curve segments into grayscale image. Then, using box-counting method to calculate the fractal dimension for each grayscale image. Finally, based on IDW method to obtain fractal dimension zoning map for each period. The results show, the whole San Zhouxi landslide is more active when during the drop period of the reservoir water level than during the rise period of the reservoir water level. Besides, from a local point of view, parts of this landslide are influenced by the changes of the reservoir water level and with different effects. In general, the deformation on right side of the landslide are serious than on the left side of the landslide, the deformation on the lower part of landslide are serious than on the upper part of the landslide.(8) Based on landslide failure probability calculation by GeoStudio and landslide deformation fractal dimension maps, San Zhouxi landslide failure probability zoning will be studied on. In this thesis, landslide failure probability analysis is based on GeoStudio simulation software. The function module SEEP/W will be used to make transient simulation of the ground water level of San Zhouxi landslide under different reservoir water scheduling cycles and different years. This ground water level simulation will consider the combined effect of rainfall and water level. After this simulation, the function module SLOP/W will be used to calculate landslide failure probability according to different simulated ground water level in different calculation periods. Then, by comparing the reliability of the simulation results and the safety factor values from landslide stability calculation in a certain calculation period, one landslide failure probability result will be chosen to stand for this corresponding calculation period. In addition, in order to modify the real boundry of the partial deformed zone of this landslide, the geological enviroment conditions and the feild survey records of San Zhouxi landslide have been combined with the obtained landslide fractal demension zoning map for analysis. Landslide partial deformation degree map will be obtained from this step and then, based on this landslide deform situation, landslide failure probability get from last step and location of the simulation profile, landslide partical failure probability will be analyzed. The results in this step shows that the failure probability zoning map represents the deformation situation of San Zhouxi landslide well, the failure probability on the right side of the landslide is higher than on the left side of the landslide. And generally speaking, the failure probability of San Zhouxi landslide, when during the drop period of the reservoir water, is higher than during the rising period of the reservoir water. Besides, by analyzing the cracks on the surface of San Zhouxi landslide, the straight and vertical to the main slip direction cracks maybe formed because of reservoir water level fluctuation and those curved and from vertical to parallel to the main slip direction cracks are more likely formed because of the drop affection of reservoir water level.(9) Based on the analysis on the distribution of elements at risk on San Zhouxi landslide, landslide risk map of this landslide is aimed to get. In this part, time scale of landslide risk is considered. The landslide risk map based on two period, one is during the rising period of reservoir water level and the other is during the dropping period of reservoir water level. The elements at risk in this case includes buildings, indoor population and agriculture and weeds land. The results show, when during the drop period of reservoir water, San Zhouxi landslide will under higher landslide risk than during the rise period of rese economic risk, when during the drop period of the reservoir water level is higher than during the rise period of the reservoir water level. In the former period, the range of the buildings’ economic risk is2,800to101,000Yuan, while in the later period, the range of the buildings’ economic risk is1,600to2,8000Yuan. Besides, for the indoor population risk, some of them are under higher risk during the drop period of the reservoir water level than during the rise period of the reservoir water level. In the former period, the indoor population risk is8persons and in the later period, the indoor population risk is4persons. In addition, for other agricultural and weeds land economic risk, during the drop period of reservoir water the range of the economic risk is933to2,160Yuan/mu, while during the rise period of reservoir water the range of the economic risk is107to933Yuan/mu.更多还原