地震诱发滑坡的危险性分析与预测

结合地震滑坡的特点和相关文献研究,介绍了地震力的分析方法、地震滑坡的机理、地震危险性分析的方法、地震活动性参数的确定方法以及场点地震危险性概率计算原则。将两种地震诱发滑坡预测结果进行对比,分析结果表明,地震滑坡危险区主要集中在中国西部地区（川、滇、甘、陕、新疆等省区）及中国台湾地区,随预测年限的增加场地的地震滑坡危险性也随之增高,地震崩塌滑坡的危险区域明显加大。     

联合DBSCAN聚类采样和SVM分类的滑坡易发性评价

针对基于机器学习的滑坡易发性评价中非滑坡样本选取不规范导致的分类精度较低问题,本文提出联合基于密度的噪声应用空间聚类(Density-Based Spatial Clustering of Applications with Noise,DBSCAN)采样策略和支持向量机(Support Vector Machine,...     

基于离心机模型试验的甘肃江顶崖古滑坡复活机理研究

位于白龙江断裂带的甘肃舟曲江顶崖古滑坡规模巨大,受断裂活动、降雨入渗与河流侵蚀和人类工程活动等因素影响,多次发生复活-堵塞白龙江灾害事件,造成极大危害。为研究江顶崖古滑坡的复活机理,本文在野外地质调查的基础上,重点开展了滑体在含水率为10%、15%和20%条件下的离心机模型试验。研究表明:在滑体含水率为10%情况下,试验结束后仅在坡体中后部产生少量裂缝,但滑坡体整体还处于稳定状态; 而在滑体含水率为15%和20%情况下,滑坡均发生了破坏,在滑体含水率分别为15%、20%情况下坡体失稳所需离心加速度分别为100g和50g。试验测试分析表明,江顶崖古滑坡为推移式滑坡,其变形先从坡体中后部开始,坡体中后部产生裂缝,随后裂缝逐渐向前缘扩展,最终裂缝贯通造成滑坡滑动破坏。滑坡体的变形过程主要分为3个阶段: ①变形启动阶段(裂缝开始形成阶段); ②变形加速阶段(裂缝加速发展阶段); ③失稳阶段。通过离心模拟试验,结合野外调查分析,认为江顶崖古滑坡复活的因素主要受降雨和孔隙水压力的影响,是受前缘河流侵蚀牵引、降雨入渗造成滑坡中后部推移的耦合滑动。     

基于多源数据分析维多利亚湖流域水储量变化

本文利用CSR发布的GRACE RL06时变重力场模型,结合两种水文模式、卫星测高、降雨和蒸散等多源数据,从多个角度综合系统地分析维多利亚湖流域2003-01—2017-06的陆地水储量变化.比较了正向建模方法和单一尺度因子对泄漏误差的改正效果,经对比采用正向建模方法在此流域效果更好.基于多源数据得出以下三点与此前研究不同的结论:(1)GRACE RL06版本数据探测到流域内的水储量在2003-01—2017-06呈增加趋势,球谐位系数和Mascon产品得到的变化速率分别为14.9 mm·a^-1和16.7 mm·a^-1,观测误差小于RL05版本的结果,RL05版本低估了流域水储量的变化速率;(2)2013-01—2016-02期间GRACE和测高探测到湖泊水量增长,而水文模式探测到流域内水储量减少,推测这一现象由大坝蓄水造成;(3)受El Ni1o事件影响,2016-03—2017-06流域降雨减少,流域水储量减少,GRACE球谐位系数和Mascon探测到的变化速率分别为-100.3 mm·a^-1和-129.7 mm·a...     

兰州市滑坡泥石流灾害与防治

本文在研究兰州市滑坡、泥石流类型、分布与发展趋势的基础上，论述了滑坡、泥石流防治现状和存在问题，指出了加强防治工作的紧迫性，提出了滑坡、泥石流灾害防治的指导思想、目标和对策，强调了开展系统防灾的重要性。     

Application of Numerical Modeling for Groundwater Flow System Analysis in the Akaki Catchment,Central Ethiopia

A three dimensional steady-state finite difference groundwater flow model is used to quantify the groundwater fluxes and analyze the subsurface hydrodynamics in the Akaki catchment by giving particular emphasis to the well field that supplies water to the city of Addis Ababa. The area is characterized by Tertiary volcanics covered with thick residual and alluvial soils. The model is calibrated using head observations from 131 wells. The simulation is made in a two layer unconfined aquifer with spatially variable recharge and hydraulic conductivities under well-defined boundary conditions. The calibrated model is used to forecast groundwater flow pattern, the interaction of groundwater and surface water, and the effect of pumping on the well field under different scenarios. The result indicates that the groundwater flows regionally to the south converging to the major well field. Reservoirs and rivers play an important role in recharging the aquifer. Simulations made under different pumping rate indicate that an increase in pumping rate results in substantial regional groundwater level decline, which will lead to the drying of springs and shallow hand dug wells. Also, it has implications of reversal of flow from contaminated rivers into productive aquifers close to main river courses. The scenario analysis shows that the groundwater potential is not enough to sustain the ever-growing water demand of the city of Addis Ababa. The sensitivity and scenario analysis provided important information on the data gaps and the specific sites to be selected for monitoring, and may be of great help for transient model development. This study has laid the foundation for developing detailed predictive groundwater model, which can be readily used for groundwater management practices.     

Site effects modelling applied to the slope affected by the Suusamyr earthquake (Kyrgyzstan, 1992)

In 1992, a large magnitude earthquake (Ms = 7.3) hit the northern part of the Kyrgyz Tien Shan range where it triggered rockslides and many debris slides or flows. One of these mass movements occurred on the Chet–Korumdy ridge located in the Suusamyr Basin. It consists of a multi-rotational debris slump in its upper part that turned into a debris flow in its lower part. Involving arenitic material overlying silty clays, it has a volume of about 0.5 to 1.10⁶ m³, a maximum thickness of 40 m and a run-out of 200 m. The field observations and measurements carried out on this slope suggest that local amplification effects could have contributed to the initiation of the seismic failure. To test this hypothesis in the lack of instrumental evidence of local ground-motion recordings, we conducted a sensitivity study of site effects based on a numerical analysis in the visco-elastic domain with a two-dimensional finite difference code. Varying the topography and the geology of the investigated slope, topographic site effects are found to be less important than geological site effects which are controlled by the contrast of impedance between the surface materials and the bedrock. The geometry of the low-velocity surface layer has also an influence on site effects, which is often difficult to be distinguished from pure topographic effects. Considering all modelling results, we conclude that site amplifications alone cannot have triggered the Suusamyr landslide during the 1992 earthquake. The static slope stability analyses done in previous studies revealed that the Suusamyr failure neither can have a purely static origin. Even if the water table is very high within the arenite layer, only a minor failure develops in the lower part of the slope. Therefore, we believe that the triggering of the Suusamyr landslide is a consequence of pore pressure build up in areas characterized by significant ground-motion amplifications.     

A Study of the hydrogeological environment of the lishan landslide area using resistivity image profiling and borehole data

Resistivity Image Profiling (RIP) surveys was used to develop a lithological and hydrogeological model of the subsurface in the southeastern part of Lishan landslide area of central Taiwan. The bedrock consists of slate in the study area. Based on RIP and rock samples collected from boreholes results, three electrical strata are recognized: colluvium, the shear zone composed of shear gouges and shattered slate, and the undisturbed slate formation. The steep shear zone with resistivity ranging between 100 ~ 260 Ω-m, plays a crucial role in the local hydrogeological environment, because it forms a natural barrier which blocks and retains groundwater flowing down the slope. Groundwater will brim over the barrier when the water level is high. Thus the inclined groundwater table remains stable from long-term monitoring. It strongly indicates that the groundwater recharge is greater than that of discharge. Therefore, the shear zone can provide information about the optimum locations for draining the excess groundwater in-situ for slope stability consideration.

The curved basal surface of the colluvium and the weathered slate can also be discerned from the resistivity variations and boreholes data. A series of circular patterns may associate with the main slope failure which migrated upwards from the lower slope.     

Modelling of atmospheric dispersion of heavy metals in the Celje area,Slovenia

The aim of this research was to determine how fast the level of heavy metal concentrations in the air decreases in relation to increasing distance from the source of pollution and what the influence area is of the zinc smelting plant which existed for 100 years in Celje. In that period it produced approximately 580,000 tons of raw Zn from sphalerite ore by the pyrometallurgical process. The production left behind a heavily contaminated area, where the concentrations of Pb and Zn in the soil can be expressed as a percentage. A model has been made on the basis of the data of concentrations of Zn and Cd in the soil and attic dust regarding the distance and direction from the source of the pollution. Because Celje lies in a basin we chose a linear model, which describes the decreasing of the concentrations of Zn and Cd only in one direction. Sampling has been conducted on the four river valleys which stretch from the source of the pollution in all four directions: north, west, south and east, up to 13 km from the source. The power function with a negative exponent was used. With the solution to the calculated functions according to the distance, we can estimate the theoretical distance when the concentrations drop to the natural background level. The range of influence of the zinc smelting plant has been estimated to be between 14 and 52 km for the presence of anthropogenic Zn in attic dust and between 9 and 14 km for the presence of anthropogenic Zn in the soil, depending on the direction from the plant. Correlations between the measured values and the ones from the model are high: from 0.75 up to 0.98.