During the dry season of December 2020, two sliding subzones of the Qingliu landslide in southwest China slid out of stability, severely damaging the buildings on the slope. To investigate the mechanism and movement of landslides in the dry season, we employed high-resolution unmanned aerial vehicle mapping, electrical resistivity tomography, on-site union boreholes, groundwater detection, deep displacement monitoring, and numerical simulation to analyze the deep geotechnical structural characteristics, groundwater runoff paths, and destabilization range and movement processes at different times. Preliminary analysis showed that the slow infiltration of rainwater during the rainy season and infiltration of snow melt in winter, topography, and loess clay layers of the slide zone type are related to the triggers of landslide instability. Four layers of rock-soil stratification interfaces with different resistivity values, revealed by electrical resistivity tomography, comprising loess-like pulverized clay, gravelly pulverized clay, and bedrock, existed at different burial depths in the longitudinal section. Borehole and displacement monitoring revealed the existence of a primary slip surface and several secondary slip surfaces, with an average thickness of 16–22 m and a maximum daily displacement at the slip surface of approximately 2.29 mm. The deepest groundwater level of the water-bearing section in the borehole was 25.8 m, and it percolates and drains through fractures in the loess-like layer. Startup acceleration, deceleration pileup, front-edge pileup stopping, and middle- to rear-edge pileup stopping are the four primary discrete element simulation movement phases. The findings help deepen the understanding of similar dry-season landslides and their disaster-causing effects.

Areas with different levels of susceptibility to landslides, rainfall warning thresholds vary widely, to improve the pertinence and accuracy of landslide monitoring and early warning. Based on field geological survey and landslide susceptibility condition analysis, this paper combines information quantity model and analytic hierarchy method to carry out susceptibility evaluation, and then analyzes the correlation between landslide occurrence probability and cumulative rainfall, and conducts landslide rainfall early warning threshold model research by zoning. The results showed that: Slope, elevation, geological structure, engineering rock group and water system are the main geological conditions of landslides in Longling County; The area of non-prone areas in Longling County was 14.33 km2, the area of low prone area was 1053.87 km2, the area of medium prone area was 1471.65 km2, and the area of high prone area was 254.73 km2; The rainfall warning time was determined for a single day and the previous 3 days, and the rainfall warning threshold was refined by district; Compared with the rainfall warning threshold model applied to the landslide monitoring and early warning in Longling County, the number of early warning information decreased by 70, the accuracy of early warning was increased by 14.4%, and the effective early warning of landslide in Shijiazhai Formation of Huba Village, Zhen’an Town was realized. This paper provides a good reference method for determining the regional landslide rainfall warning threshold.

Debris flows is one of the most common natural disasters in mountainous areas, posing a seriously risk to local people’s life and property. It is fundamental basis to study the criteria for movement of solid materials subjected to seepage flow and surface flow for the purpose of prevent this hazard. Therefore, mechanical analysis methods and laboratory experiments were used to study the effect of seepage flow on movable solid materials in debris flow. First, the definition of movable solid materials was proposed. Then, a geological model of debris flow is established considering saturated seepage flow. Finally, through mechanical analysis, formulas for dynamical force and resistance force are derived. The results show that the dynamical force and resistance force increase linearly with depth when the geologic model is homogenous and the seepage flow saturates the entire debris layer. It also indicated that pore-water pressure is one of the most important factors for causing debris flow, especially when the slope angle exceeds 12°. Through comparing the results of tests and theoretical analysis under saturated seepage flow, the discrepancy is only 1.3%–24.2%, showing that the formulas are fairly reliable. The motion of the solid materials should be described as a mechanical problem rather than a statistic qualitative description. The research contributes to the source volume calculation of small debris-flow watersheds and advances the study of the movable solid materials in complex dynamic conditions.

The upstream Fujiang River are famous for their high mountains and narrow canyons, which results in a conflict of interest between local residents and land use. To make good use of precious land resources is a meaningful work for local people and government. Therefore, field surveys and theoretical analysis were carried out in the upstream Fujiang River to explore the land-use evaluation and utilization advice. Firstly, we analyzed the factors which affect the land use of debris flow depositional area. Secondly, we chose the factors of soil fertility quality, soil particle conservation, and the geological engineering condition to set up the land-use evaluation method. Thirdly, through index classification, we give the planting type, land-use type, construction type respectively, according to grading and assignment value for each factor, we built the debris flow disaster-prone land utilization mode R by using an analytical hierarchy process method. Lastly, taking Huangjiaba village as an example, based on the debris flow disaster land-use evaluation method and debris flow hazard evaluation, we identified four land-use scenarios. The results show that the value of the four scenarios is between 1.00 and 4.00, the four scenarios utilization advices are given based on each R-value and Huangjiaba natural condition. It also obtained that the developmental tendencies of the debris flow disaster areas appear to deposit recently, the frequency of debris-flow activity is evolving from high to stable, on making good use of debris flow deposit fan’s usage is necessary to explore the disaster prone land and avoid disaster loss. Further studies need to systematically consider more factors to evaluate debris flow and disaster-prone land utilization, which can provide a reference for the rural space planning and revitalization for the local government.

北川断裂带位于龙门山中央断裂带中部,新、老滑坡较为发育,构造活动是影响区内滑坡发生的主导因素.采用文献记载、现场调研等方法,分析了构造对滑坡灾害的影响,结果表明:① 构造横向挤压、不均匀抬升对地表岩体的完整性进行改造,使得不同构造部位、斜坡部位岩体存在结构差异,进而控制滑坡在空间上的发育规律,同时,细部构造结构面在空间上的产出关系构成了滑坡发生的初始边界条件;② 作为构造活动的剧烈外部表现,地震动荷载直接诱发滑坡的同时造成斜坡岩体的松动;③"5·12冶震后,区域构造应力方向发生近90°的偏转,进一步加剧了松动岩体的变形与破坏,震后应力偏转是影响区域斜坡稳定的最主要内动力因素.

为研究汶川8级地震震后10年内灾区地质灾害的发育演变状况,选取极重灾区平武县石坎河流域作为研究对象,采用多期遥感解译以及地面调查相结合的方式,对汶川地震重灾区震后10年泥石流发育概况以及其发展演变规律进行研究分析.研究结果表明:①石坎河流域沿主河道分布了众多支沟,每年雨季石坎河流域泥石流暴发呈现明显的群发性.在震后10年间,石坎河流域内崩滑堆积体数量及面积总体均呈下降趋势,但残余物源方量仍较高,泥石流仍具有发生频率高、 冲出量大、 破坏性强的特点.②汶川震区的高密度物源发育特征导致区内部分洪水沟或常年流水沟转化为泥石流沟,以及某些处于停歇期的老泥石流沟重新复活,进入发展期.③受地形坡度以及汛期影响,地震所形成的崩塌、 滑坡物源,在震后10年间大量进入沟道,转变为沟道堆积物,或以泥石流堆积物的形式沿主沟堆积.④在工程约束条件下,部分泥石流沟的启动物源分布位置以及物源类型发生较大改变,泥石流形成机制和运移过程也相应发生变化.⑤震区泥石流在主沟与主河交汇处形成大量泥石流扇形堆积,进入主河堆积体进一步抬升河床,给主河两岸或沟口人民生产生活造成不便,影响该区域地质环境.

滑坡受控于地质环境条件和坡体地质结构,不同地质结构的斜坡失稳破坏的模式存在差异,本文以后龙门山千枚岩区为例,基于现场调查,梳理总结了区内岩质滑坡发生的力学模式与斜坡地质环境、坡体结构之间的关系,进而选取控制滑坡发生的关键因素,运用ARCGIS软件的加权叠加功能定量划分了不同模式滑坡的易发区域,主要取得以下认识:(1)滑移-拉裂式滑坡主要发生在坡度30°～45°的顺向飘倾坡内、滑移-溃曲式滑坡发生在坡度30°～45°的顺向伏倾坡内、倾倒变形主要发生在岩层倾角＞65°的反向斜坡内;(2)区内倾倒变形易发区面积为8.73km2、滑移拉裂易发区面积为4.31 km2、滑移溃曲易发区面积为3.28 km2,以倾倒变形类型的滑坡为主,已发生滑坡与易发分区结果比对证明了滑坡易发分区与实际情况基本吻合.

北川县筲箕窝滑坡为滑移—溃曲形成的老滑坡,"5.12"地震作用下,该老滑坡堆积体发生复活,中后部形成多级裂缝.基于滑坡的地震复活变形特征,采用Flac3d有限差分法模拟地震对滑坡复活的作用机制,进而根据极限平衡理论进行了稳定性计算.研究结果表明:(1)地震加剧了堆积体变形,是老滑坡复活的诱发因素,复活变形仅发生在老滑坡堆积体内部,滑面为基覆界面,下伏基岩未发生变化,且复活变形受地形坡度及堆积体厚度的限制;(2)地震形成的地表裂缝有利于降雨入渗,降雨成为诱发地震复活体进一步失稳破坏的主要诱因,在暴雨工况下,老滑坡整体处于稳定状态,仅局部复活体可能进一步发生破坏.

地质灾害防治的一条有效途径就是进行地质灾害区划与风险研究,进一步圈定地质灾害高风险区域,可节约防治成本并达到风险评价的效果.北川县开坪乡地质地貌复杂,发育各类地质灾害,本文在地质灾害详细调查的基础上,拟对区内地质灾害进行风险性评价,以单个滑坡的体积、面积、高差、河流距离、岩性、变形迹象等因子作为分析单元,实现大比例尺范围内滑坡危险性区划;制作出区域内的地质灾害危险性图件与易发性图件;根据遥感影像解译,原有资料查询以及实际考察,制作开坪乡研究区域斜坡类型分布图;结合单个滑坡危险性及易损性,区域危险性及易损性,综合制作开坪乡区域风险性图件,完成对研究区进行有效地地质灾害风险区划.

强震区地震后大量的崩塌堆积体堆积于高陡斜坡中上部,堆积体远离居民点,一旦诱发为坡面泥石流,形成新的次生地质灾害,将严重威胁下方居民的生命财产安全.本文以北川县开坪乡平石板坡面泥石流为例,平石板沟“5.12”地震崩塌堆积体在2010、2013年强降雨作用下失稳转变为坡面泥石流淤积场镇.在平石板泥石流暴发特征介绍基础上,通过粒径不均匀系数、堆积体启动判别指标、后缘汇水面积等来分析崩塌堆积体启动条件及影响因素,并针对此类灾害发育特征,提出了通过上游稳拦固源方法进行治理的防治思路.以期为研究高陡斜坡堆积体的启动机制及防治提供一定的借鉴意义.

High-speed landslide is a catastrophic geological disaster in the mountainous area of southwest China. To predict the movement process of landslide reactivation in Chenjiaba town, Beichuan county, Sichuan province, China, we simulated the movement process of two landslide failures in Chenjiaba via rapid mass movement simulation and unmanned aerial vehicle images (UAV), and obtained the movement characteristic parameters of the landslides. According to a back analysis, the most remarkable fitting rheological parameters were friction coefficient (μ = 0. 18) and turbulence (ξ = 400 m · s -2 ). The parameter of landslide pressure was applied as the zoning index of landslide hazard to obtain the influence zone and hazard zoning map of the Chenjiaba landslide. Results show that the Duba River was blocked quickly with a landslide accumulation at the maximum height of 44.14 m when the Chenjiaba deposits lost stability. The hazard zoning map indicated that the landslide hazard degree is positively correlated with the slope. This landslide assessment is a quantitative hazard assessment method based on a landslide movement process and is suitable for high-speed landslide. Such method can provide a scientific basis for urban construction and planning in the landslide hazard area to avoid hazards effectively.

为了研究岷江上游震后泥石流活动特征和易发程度,结合高精度遥感影像和历史灾害统计资料,系统分析区内泥石流活动特征;在Matlab软件支持下,采用可拓模糊物元模型,选取松散物源、地层岩性、年降雨量、流域面积、主沟纵比降、完整系数、坡度、地震烈度、人类活动9个影响因子作为评价参数,并将岷江上游典型泥石流划分为极高、高、中、低易发4个等级,同时采用谭炳炎打分法对典型泥石流沟严重程度数量化综合评判,通过对两种方法比较分析,结果表明,整个岷江上游泥石流以中易发性为主且主要沿都汶公路沿线、杂谷脑干流分布;极高、高易发泥石流沟分布在汶川-理县一带,研究区易发程度由汶川县城附近沿岷江上、下游递减;评价结果对岷江上游灾后重建和生态恢复具有一定的借鉴和参考价值;模糊可拓物元模型能更好的与历史泥石流灾害分布情况相吻合,分级层次更加明显,为泥石流易发性评价提供了一种定性和定量解决问题的方法.

红石岩堰塞湖是2014-08-03鲁甸地震诱发形成的大型堰塞湖,由红石岩崩塌堵断牛栏江形成.红石岩堰塞坝坝高约96 m,堆积体总方量约1 200 × 104 m3,湖区满库库容为2.6×108 m3.从红石岩堰塞湖形成的背景条件,以及堰塞湖对坝址所在流域构成的潜在灾害链效应,评估堰塞湖的溃决危险程度.同时根据可能的溃决形式分析,采用1/3和1/2溃决模式对堰塞湖溃坝洪水估算,得到两种工况条件下的峰值流量分别为:Qp≈(1.3～1.5)×104 m3/s和Qp≈(2.2 ～2.8)×104 m3/s,远超过坝址处500 a一遇的牛栏江暴雨洪水,并在此基础上对下游演进过程的洪水进行估算.认为红石岩堰塞湖在后期整治中仍存在库岸稳定、堰塞坝稳定和鱼类生态破坏等问题,应引起关注.

According to the fact that the database of wide-area provides small amounts of data and Low Accuracy Data and Thematic map drawing complex step. Through the selection of data model and the ap-plication of a new database framework to improve it. The database ’s data model is focused on regional vulnerability assessment model,combined with GeoDatabase model. The ArcCatalog was used to manage the database. The database structure was composed by the original database and the results database. The original database saves the original data,and has the function of data backup;The results database saves the result data of finishing data analysis process;Finally,the thematic maps was finished by using the da-tabase in the study area of the upper reaches of Min River. The results show that the database of vulnera-bility assessment for the mountains of the upper reaches of Min River is able to preserve the factor data of the vulnerability assessment,to improve the efficiency and precision of the regional vulnerability assess-ment in the study area,and tosimplify the thematic mapping procedures,improve the efficiency of themat-ic mapping. The database could provide effective technical support to the sustainable development of the upper reaches of Min River.

通过本次调查, 以定性评价方法对不同灾种易发程度进行分区, 并结合实际情况综合划分地质灾害易发区, 将北川县划分为地质灾害高易发区、 中易发区、 低易发区三大类, 共3个区10个亚区.

[目的]分析汶川震区哈尔木沟堵河型泥石流灾害特征,为堵河型泥石流灾害防治提供借鉴.[方法]通过震后历次泥石流跟踪调查,分析哈尔木沟地质环境演变过程.利用雨洪法等计算了泥石流运动特征参数,并采用经验公式计算了不同频率的泥石流堵河可能性.[结果]哈尔木沟泥石流流体特性、交汇条件和主河水文条件均有利于泥石流堵河,4个经验公式计算均显示,P=1％(100年一遇泥石流)以上规模的泥石流有严重堵河风险.对哈尔木沟治理工程运行情况进行跟踪调查分析,发现经过3个水文年共7次泥石流灾害的检验,治理工程防灾效果明显,但同时还存在拦挡工程平面布局不合理、坝肩渗流、溢流口淤积、排导槽冲刷损毁等问题,影响了防治工程的安全可靠度及防灾效果.[结论]针对哈尔木沟泥石流发育特征,应通过增设拦挡工程,修复加固排导槽等方法进行治理.

Geomorphic features of a gully is an important slowly varying factor in the processes of debris flow,which determine the driving forces of debris flow,restrict the surface runoff converge among water source conditions and influence the ways of solid material supply.Therefore,debris flow occurrence can be analyzed by the geomorphic features of a drainage basin.By taking a rainstorm-induced debris flow gullies in the middle of Zagunao River basin as the research object,the relationships among geomorphic information entropy in gully development stages,basin area,longitudinal channel bed gradient and debris flow disaster characteristics are analyzed.Geomorphic information entropy of the high frequency debris flow gullies is found to be 0.12~0.20 and the low frequency debris flow gully,0~0.12 and 0.20~0.30,respectively.When gully area is 〉15 km2 and longitudinal channel bed gradient is 〈300‰,debris flow is watery,and on the contrary,is viscous.

A Ms 8.0 large earthquake occurred in Sichuan, China on May 12, 2008 (hereafter called 5.12 Earthquake), and then a large debris flow happened in the quake-hit Qingping Township of Mianzhu county on August 13, 2008 (hereafter called 8.13 Debris Flow). The influence of two disasters on the changes in land use were analyzed by using high-resolution aerial photos and satellite remote sensing images taken before and after the 5.12 Earthquake and 8.13 Debris Flow, the selection of suitable construction land were studied by learning experiences and lessons from the selection of resettlement areas and through field surveys and with land use transfer model and analytical model in combination with RS and GIS. The results showed that the influence of the 5.12 Earthquake on ecological environment was far greater than that of the 8.13 Debris Flow; there were more salient conflicts between population and land after the earthquake. Sites for post-disaster reconstruction should not be in disaster-prone areas or in gully-facing areas. Suitable land for settlement construction in I-1∼I-5 low-hazard zones is optimal settlement areas for post-disaster reconstruction.