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21.
Nine Landsat TM tapes and images and MSS images, 10 NOAA tapes and images and 1 SAR image from 1973 to 1997 were used to analyse the diffusion of suspended sediments and the change of tidal radial sand ridges in the northern part of the Changjiang River delta, the South Yellow Sea. The results showed that the diffusion of suspended sediments was controlled by the tide, net current, and submarine topography in this area. The distribution of suspended sediments had close relationship with thesubmarine topography. The old Huanghe River delta and the Changjiang River comprise the main sediment supply for the formation of radial sand ridges, whose evolution can be divided into three stages since the Huangbe River changed its course and flowed northward into the Bohai Sea. 相似文献
22.
23.
A theoretical model for wind‐sand flow is developed by considering the coupling between wind flow and sand particle motion, the latter subject to the Magnus effect, under different atmospheric stability conditions. Using this model, the characteristics of the wind‐sand flow are discussed in detail. The results show that the atmospheric stability and the Magnus effect both have a strong influence on wind profiles and on the trajectories of sand particles. This approach produces results with characteristics that differ from those previously reported; the latter only applying to atmospheric conditions of neutral stability. The saltating sand reaches a greater height under non‐neutral stability than under neutral stability, while the maximum horizontal distance is greater under unstable conditions and is smaller under stable conditions than under conditions of neutral stability. 相似文献
24.
Controlling of landsides safely and economically is a great challenge to mine operators because landslides are major geological
problems especially in open-pit mines. In this paper, a case history at Panluo open-pit mine is presented in detail to share
the experiences and lessons with mine operators. Panluo open-pit mine is located in the southwestern Fujian province of China.
It is the largest open-pit iron mine in the Fujian province and was planned in 1965 and is in full operation from 1978. In
July 1990, an earthquake of magnitude 5.3 in Taiwan Strait and big rainstorms impacted the mine slope, causing tension cracks
and rather large-scale failures, and forming a U-shaped landslide. Total potential volume was estimated to be up to 1.0 × 106 m3. This directly threatened the mine production. In order to protect the mine production and the dwellers’ safety around, a
dynamic comprehensive method was implemented including geotechnical investigations, in-situ testing and monitoring, stability
analysis, and many mitigation and preventive measures. These measures slowed down the development and further occurrence of
the landslide. The results showed that the landslides were still active, it was slowed with the control measures and moved
rapidly with rainfall and mining down. However, no catastrophic accidents occurred and the pit mining was continued till it
was closed at the elevation of 887 m in 2000. As a successful case of landslide control at an open-pit mine for 10 years,
this paper reports the controlling measures in details. These experiences of landslide control may be beneficial to other
similar mines for landslide control. 相似文献
25.
Laura Chiaramonte Mark D. Zoback Julio Friedmann Vicki Stamp 《Environmental Geology》2008,54(8):1667-1675
This paper reports a preliminary investigation of CO2 sequestration and seal integrity at Teapot Dome oil field, Wyoming, USA, with the objective of predicting the potential risk
of CO2 leakage along reservoir-bounding faults. CO2 injection into reservoirs creates anomalously high pore pressure at the top of the reservoir that could potentially hydraulically
fracture the caprock or trigger slip on reservoir-bounding faults. The Tensleep Formation, a Pennsylvanian age eolian sandstone
is evaluated as the target horizon for a pilot CO2 EOR-carbon storage experiment, in a three-way closure trap against a bounding fault, termed the S1 fault. A preliminary geomechanical
model of the Tensleep Formation has been developed to evaluate the potential for CO2 injection inducing slip on the S1 fault and thus threatening seal integrity. Uncertainties in the stress tensor and fault
geometry have been incorporated into the analysis using Monte Carlo simulation. The authors find that even the most pessimistic
risk scenario would require ∼10 MPa of excess pressure to cause the S1 fault to reactivate and provide a potential leakage
pathway. This would correspond to a CO2 column height of ∼1,500 m, whereas the structural closure of the Tensleep Formation in the pilot injection area does not exceed
100 m. It is therefore apparent that CO2 injection is not likely to compromise the S1 fault stability. Better constraint of the least principal stress is needed to
establish a more reliable estimate of the maximum reservoir pressure required to hydrofracture the caprock. 相似文献
26.
For the assessment of shallow landslides triggered by rainfall, the physically based model coupling the infinite slope stability
analysis with the hydrological modeling in nearly saturated soil has commonly been used due to its simplicity. However, in
that model the rainfall infiltration in unsaturated soil could not be reliably simulated because a linear diffusion-type Richards’
equation rather than the complete Richards’ equation was used. In addition, the effect of matric suction on the shear strength
of soil was not actually considered. Therefore, except the shallow landslide in saturated soil due to groundwater table rise,
the shallow landslide induced by the loss in unsaturated shear strength due to the dissipation of matric suction could not
be reliably assessed. In this study, a physically based model capable of assessing shallow landslides in variably saturated
soils is developed by adopting the complete Richards’ equation with the effect of slope angle in the rainfall infiltration
modeling and using the extended Mohr–Coulomb failure criterion to describe the unsaturated shear strength in the soil failure
modeling. The influence of rainfall intensity and duration on shallow landslide is investigated using the developed model.
The result shows that the rainfall intensity and duration seem to have similar influence on shallow landslides respectively
triggered by the increase of positive pore water pressure in saturated soil and induced by the dissipation of matric suction
in unsaturated soil. The rainfall duration threshold decreases with the increase in rainfall intensity, but remains constant
for large rainfall intensity. 相似文献
27.
Shear strength characterization of municipal solid waste at the Suzhou landfill, China 总被引:5,自引:0,他引:5
The current practice of slope stability analysis for a municipal solid waste (MSW) landfill usually overlooks the dependence of waste properties on the fill age or embedment depth. Changes in shear strength of MSW as a function of fill age were investigated by performing field and laboratory studies on the Suzhou landfill in China. The field study included sampling from five boreholes advanced to the bottom of the landfill, cone penetration tests and monitoring of pore fluid pressures. Twenty-six borehole samples representative of different fill ages (0 to 13 years) were used to perform drained triaxial compression tests. The field and laboratory study showed that the waste body in the landfill can be sub-divided into several strata corresponding to different ranges of fill age. Each of the waste strata has individual composition and shear strength characteristics. The triaxial test results showed that the MSW samples exhibited a strain-hardening and contractive behavior. As the fill age of the waste increased from 1.7 years to 11 years, the cohesion mobilized at a strain level of 10% was found to decrease from 23.3 kPa to 0 kPa, and the mobilized friction angle at the same strain level increasing from 9.9° to 26°. For a confinement stress level greater than 50 kPa, the shear strength of the recently-placed MSW seemed to be lower than that of the older MSW. This behavior was consistent with the cone penetration test results. The field measurement of pore pressures revealed a perched leachate mound above an intermediate cover of soils and a substantial leachate mound near the bottom of the landfill. The measurements of shear strength properties and pore pressures were utilized to assess the slope stability of the Suzhou landfill. 相似文献
28.
29.
遥感在滑坡灾害研究中的应用进展 总被引:9,自引:1,他引:8
在对常用的光学遥感卫星影像、InSAR,LiDAR等遥感技术方法介绍的基础上,综述了这些方法在滑坡研究中的最新应用进展,从滑坡风险评估中的基础地形数据获取、滑坡编录与制图、监测、滑坡因素制图、承灾体制图等5个方面阐述遥感技术在滑坡风险中的支撑技术作用与应用前景。从遥感影像在滑坡风险评估中的作用、解译能力、影响解译的因素、精度评价和遥感数据源选择等角度阐述了常用遥感技术在滑坡风险评估应用中存在的问题,认为: ① 遥感技术在滑坡风险评估中的主要作用为数据、信息的获取与更新;② 滑坡的遥感影像解译能力取决于影像空间分辨率与待识别滑坡大小的相对关系,影像的时间分辨率、滑坡与其周边环境的对比度、立体影像的获取能力是利用遥感影像开展滑坡探测、识别与制图的关键要素;解译方法和解译员的专业素质是滑坡遥感解译的重要影响因素;③ 遥感影像与GIS空间分析、3D可视化的综合可有效增强滑坡识别与制图的效率和精度;④ 对于遥感解译滑坡的精度评价应针对具体影像的可解译性从有效解译,错误解译和遗漏解译三个方面予以客观评价;⑤ 滑坡风险评估应针对具体应用,从成本效益比的角度,本着“够用为止”原则合理选用遥感数据源。 相似文献
30.
Landslides pose a serious physical and environmental threat to vulnerable communities living in areas of unplanned housing
on steep slopes in the Caribbean. Some of these communities have, in the past, had to be relocated, at costs of millions of
dollars, because of major slides triggered by tropical storm rainfall. Even so, evidence shows that: (1) risk reduction is
a marginal activity; (2) there has been minimal uptake of hazard maps and vulnerability assessments and (3) there is little
on-the-ground delivery of construction for risk reduction. This article directly addresses these issues by developing a low-cost
approach to the identification of the potential pore pressure changes that trigger such slides we seek to address these three
commentaries directly. A complex 45–60° slope site in St Lucia, West Indies was selected as a pilot for a modelling approach
that uses numerical models (FLAC and CHASM) to verify the need for surface water management to effectively reduce landslide
risk. Following the model confirmation, a series of drains were designed and constructed at the site. Post-construction evidence
indicates the methodology to be sound, in that the site was stable in subsequent 1-in-1 to 1-in-4 year rainfall events. A
critical feature of the approach is that it is community-based from data acquisition through to community members participating
in construction. 相似文献