Effect of soil hydraulic properties model on slope stability analysis based on strength reduction method   总被引：2，自引：0，他引：2  

Muhammad Mukhlisin  Marlin Ramadhan Baidillah  Aniza Ibrahim  Mohd. Raihan Taha 《Journal of the Geological Society of India》2014,83(5):586-594

Soil hydraulic properties models which have been proposed were derived based on the empirical fitting curve such as Brooks-Corey model (BC) and Van Genuchten model (VG), or based on soil pore radius distribution such as Lognormal model (LN). Each model has different accuracy for predicting soil moisture distribution. In the analysis of rainfall-induced slope failure, the soil hydraulic properties model was needed to describe the physical phenomena of behavior characteristic of water in unsaturated soil. As moisture content has an effect on soil strength, it is vital to select the suitable soil hydraulic properties model for predicting Factor of Safety (FOS) especially in forecasting landslide hazard. In this study, a numerical model of seepage finite element analysis using BC, VG, and LN model were used and compared in order to analyze the soil moisture distribution, water movement phenomenon, and slope stability characteristic in unsaturated soil slope based on the strength reduction method (SRM). The results showed that the variations of the parameters predicting the moisture content of soil leads to differences of FOS in some cases. The parametric study showed that for the unsaturated soil condition, BC model has the greatest FOS value than the other model, while VG model has the lowest. On the other hand, the FOS of all models have the same result for the saturated condition. Other than that, it was found that the increasing of ESP value in the surface layer has significant effect in the sub-surface layer.  相似文献   

Extreme rainfall events: evaluation with different instruments and measurement reliability     

Helmi Saidi  Marzia Ciampittiello  Claudia Dresti  Laura Turconi 《Environmental Earth Sciences》2014,72(11):4607-4616

With regard to extreme events, it is well documented that an intensity of about 1 mm/min already represents an extreme intensity. Under alpine conditions, a precipitation event with an intensity of 3 mm/min has occurred. Therefore, the rain gauges in this region have to be able to measure in this and even in higher intensity ranges. This study deals with basic automated tipping-bucket rain (TBR) gauge and Bulk precipitation samplers, which are able to hold more than 95 % of the cumulative rainfall, that are verified within the space of the week without losses during the extreme events and with minimal evaporation loss. Bulk samplers collected more rainfall than TBR gauges in 110 of 221 extreme events analysed over the past 10 years. In 17 extreme events, an underestimation greater than 10 % was evaluated. The objective was to single out the counting errors associated with TBR gauge, during extreme events, so as to help the understanding of the measured differences between instruments in the field. We want to determine whether the automated precipitation gauge can provide a reliable and precise measurement of precipitation with particular interest regarding heavy and extreme events.  相似文献   

REE mineralization in the carbonatites of the sung valley ultramafic-alkaline-carbonatite complex,Meghalaya, India   总被引：1，自引：0，他引：1  

Mohd. Sadiq  A. Ranjith  Ravi Kumar Umrao 《Central European Journal of Geosciences》2014,6(4):457-475

The Early Cretaceous Sung Valley Ultramafic-Alkaline-Carbonatite (SUAC) complex intruded the Proterozoic Shillong Group of rocks and located in the East Khasi Hills and West Jaintia Hills districts of Meghalaya. The SUAC complex is a bowl-shaped depression covering an area of about 26 km² and is comprised serpentinised peridotite forming the core of the complex with pyroxenite rim. Alkaline rocks are dominantly ijolite and nepheline syenite, occur as ring-shaped bodies as well as dykes. Carbonatites are, the youngest intrusive phase in the complex, where they form oval-shaped bodies, small dykes and veins. During the course of large scale mapping in parts of the Sung Valley complex, eleven carbonatite bodies were delineated. These isolated carbonatite bodies have a general NW-SE and E-W trend and vary from 20–125 m long and 10–40 m wide. Calcite carbonatite is the dominant variety and comprises minor dolomite and apatite and accessory olivine, magnetite, pyrochlore and phlogopite. The REE-bearing minerals identified in the Sung Valley carbonatites are bastnäsite-(Ce), ancylite-(Ce), belovite-(Ce), britholite-(Ce) and pyrochlore that are associated with calcite and apatite. The presence of REE carbonates and phosphates associated with REE-Nb bearing pyrochlore enhances the economic potential of the Sung Valley carbonatites. Trace-element geochemistry also reveals an enrichment of LREEs in the carbonatites and average ΣREE value of 0.102% in 26 bed rock samples. Channel samples shows average ΣREE values of 0.103 wt%. Moreover, few samples from carbonatite bodies has indicated relatively higher values for Sn, Hf, Ta and U. Since the present study focuses surface evaluation of REE, therefore, detailed subsurface exploration will be of immense help to determine the REE and other associated mineralization of the Sung Valley carbonatite prospect.  相似文献   

Predicting the geotechnical performance of Lisan Marl using finite element analysis,Dead Sea area     

Ziad Mansour  Zamri Chik  Mohd Raihan Taha 《Natural Hazards》2010,54(3):931-947

This paper investigates the changes in Lisan Marl properties upon leaching the soluble minerals and collapse potential. Finite element method was used to model dike construction and the relationships between soil parameters. To validate the chosen model and obtain the required input data, one dimensional oedometer and drained direct shear tests were carried out. The models were further validated by comparing the results with available published data. The results proved that the chosen model is efficient in assessing the geotechnical behavior of the studied soil.  相似文献   

Grain-size distribution and subsurface mapping at the Setiu wetlands,Setiu, Terengganu     

Rosnan Yaacob  Mohd Zaini Mustapa 《Environmental Earth Sciences》2010,60(5):975-984

A study was carried out around the lagoon and coastal area of Setiu wetlands to determine the general characteristics and grain-size distribution of their sediments. Sediment samples were collected from 39 stations of the lagoon area and 8 stations of the coastal area, and were analyzed for their sedimentological characteristics (mean, sorting, skewness and kurtosis). The sediment mean size ranged between 0.06–2.52 and 2.12–2.69 phi (Ø) for both lagoon and coastal sea-bottom sediments, respectively. Generally, the sediments in the study area consist mostly of coarse to fine particles. The major portions of the sediment are negatively skewed. This indicates that the study area is under the influence of the rather strong wave and current action. The study also encompassed the geophysical survey that was conducted near the coastal zone of the study area. The high-resolution seismic sub-bottom profiling technique is the standard method employed to map geological features and locate structures below the surface of the seafloor. Data obtained from seismic records were used to interpret the seismic reflectors. Three main reflectors (layers), which consist of the seabed and the seabed multiple, were traced using Sonar Web Pro software, and the results showed a uniform distribution pattern for all stations surveyed. It is envisaged that this method could be an effective way to image the marine subsurface structures; thus, its use is anticipated in the higher degrees of sedimentary research and marine resource exploration.  相似文献   

The phase-space structure of cold dark matter haloes: insights into the Galactic halo     

Amina Helmi  †  Simon D. M. White  Volker Springel 《Monthly notices of the Royal Astronomical Society》2003,339(3):834-848

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Regional analysis of annual maximum rainfall using TL-moments method     

Ani Bin Shabri  Zalina Mohd Daud  Noratiqah Mohd Ariff 《Theoretical and Applied Climatology》2011,104(3-4):561-570

Information related to distributions of rainfall amounts are of great importance for designs of water-related structures. One of the concerns of hydrologists and engineers is the probability distribution for modeling of regional data. In this study, a novel approach to regional frequency analysis using L-moments is revisited. Subsequently, an alternative regional frequency analysis using the TL-moments method is employed. The results from both methods were then compared. The analysis was based on daily annual maximum rainfall data from 40 stations in Selangor Malaysia. TL-moments for the generalized extreme value (GEV) and generalized logistic (GLO) distributions were derived and used to develop the regional frequency analysis procedure. TL-moment ratio diagram and Z-test were employed in determining the best-fit distribution. Comparison between the two approaches showed that the L-moments and TL-moments produced equivalent results. GLO and GEV distributions were identified as the most suitable distributions for representing the statistical properties of extreme rainfall in Selangor. Monte Carlo simulation was used for performance evaluation, and it showed that the method of TL-moments was more efficient for lower quantile estimation compared with the L-moments.  相似文献   

Adsorption of Pb(II) Ions from Aqueous Solutions by Date Bead Carbon Activated with ZnCl2     

Mohammed Danish  Rokiah Hashim  Mohd Rafatullah  Othman Sulaiman  Anees Ahmad  Govind 《洁净——土壤、空气、水》2011,39(4):392-399

This study reports on the adsorption characteristics of Pb(II) ions from aqueous solutions using ZnCl₂‐activated date (Phoenix dactylifera) bead (ADB) carbon with respect to change in adsorbent dosage, initial pH, contact time, initial concentration, and temperature of the solution. Kinetic studies of the data showed that the adsorption follows the pseudo‐second‐order kinetic model. Thermodynamic parameters, enthalpy change (ΔH° = 55.11 kJ/mol), entropy change (ΔS° = ? 0.193 kJ/mol/K), and Gibbs free energy change (ΔG°) were also calculated for the uptake of Pb(II) ions. These parameters show that adsorption on the surface of ADB was feasible, spontaneous in nature, and endothermic between temperatures of 298.2 and 318.2 K. The equilibrium data better fitted the Langmuir and Freundlich isotherm models than the D–R adsorption isotherm model for studying the adsorption behavior of Pb(II) onto the ADB carbon. It could be observed that the maximum adsorption capacity of ADB was 76.92 mg/g at 318.2 K and pH 6.5.  相似文献   

A review of applying second-generation wavelets for noise removal from remote sensing data   总被引：1，自引：0，他引：1  

Ladan Ebadi  Helmi Z. M. Shafri  Shattri B. Mansor  Ravshan Ashurov 《Environmental Earth Sciences》2013,70(6):2679-2690

The processing of remotely sensed data includes compression, noise reduction, classification, feature extraction, change detection and any improvement associated with the problems at hand. In the literature, wavelet methods have been widely used for analysing remote sensing images and signals. The second-generation of wavelets, which is designed based on a method called the lifting scheme, is almost a new version of wavelets, and its application in the remote sensing field is fresh. Although first-generation wavelets have been proven to offer effective techniques for processing remotely sensed data, second-generation wavelets are more efficient in some respects, as will be discussed later. The aim of this review paper is to examine all existing studies in the literature related to applying second-generation wavelets for denoising remote sensing data. However, to make a better understanding of the application of wavelet-based denoising methods for remote sensing data, some studies that apply first-generation wavelets are also presented. In the part of hyperspectral data, there is a focus on noise removal from vegetation spectrum.  相似文献   

An effective visualization and comparison of online terrain draped with multi-sensor satellite images     

Ruzinoor Che Mat  Abdul Rashid Mohamed Shariff  Biswajeet Pradhan  Ahmad Rodzi Mahmud  Mohd Shafry Mohd Rahim 《Arabian Journal of Geosciences》2013,6(12):4881-4889

The objective of this paper is to discuss the effectiveness of visualizing online 3D terrain draped with different satellite imageries. The topographic data of the study area were obtained from the contour maps of Universiti Putra Malaysia, Selangor, Malaysia. The high resolution satellite imageries used in this project involving QUICKBIRD (0.6 m resolution), IKONOS (1 m resolution), and SPOT5 (5 m resolution). R2V software was used for editing the contour data, whereas Arc GIS was used for overlaying the imageries over the 3D terrain data. Then the data were exported into Virtual Reality Markup Language to compare the effectiveness of different satellite imageries based on the data file size, imageries size, number of images tile, loading time during office hours (from 8 a.m. to 5 p.m.) and out of office hours (after 5 p.m.), frame rate per second, and visualization quality. The results revealed that IKONOS satellite imageries are better for an effective online 3D terrain visualization utilizing GIS data even though it has lower resolution compared to QUICKBIRD.  相似文献