Investigation of Failed Slopes Based on a New Method of Back Analysis in Rock Masses: A Case Study

Geotechnical and Geological Engineering - Small variation in shear strength parameters results in remarkable changes in the safety factor (SF) of a rock slope. In this regard, rock mass strength of...     

Determination of failure probabilities of flood defence systems with improved dynamic bounds method

In this paper, we describe the computational framework of a novel method for solving the challenging problem of probabilistic finite elements. The method is called Improved Dynamic Bounds (IDB) and was developed recently to improve the efficiency of the dynamic bounds. The IDB is used in finite element numerical models to calculate time-dependent failure analyses of structures. In applications, the IDB can speed up the overall simulation process by several orders of magnitude. In applications controlled by two influential variables (e.g, two-dimensional problem), the computational efficiency is improved by a factor of 769 according to Rajabalinejad (2009). Applications of IDB indicate the method is most efficient for problems where the number of influential variables are limited. This is often the case for geotechnical and coastal flood defence systems. The IDB method is applied in this paper to the 17th Street Flood Wall, a component of the flood defence system (levee infra-structure) that failed during the Hurricane Katrina, to calculate the failure probability of an I-wall.     

Impact assessment of land cover changes on the runoff changes on the extreme flood events in the Kelantan River basin

In the current years, changing the land cover/land use had serious hydrological impacts affecting the flood events in the Kelantan River basin. The flood events at the east coast of the peninsular Malaysia got highly affected in the recent decades due to several factors like urbanisation, rapid changes in the utilisation of land and lack of meteorological (i.e. change in climate) and developmental monitoring and planning. The Kelantan River basin has been highly influenced due to a rapid change in land use during 1984 to 2013, which occurred in the form of transformation of agricultural area and deforestation (logging activities). In order to evaluate the influence of the modifications in land cover on the flood events, two hydrological regional models of rainfall-induced runoff event, the Hydrologic Engineering Center (HEC)-Hydrologic Modeling System (HMS) model and improved transient rainfall infiltration and grid-based regional model (Improved TRIGRS), were employed in this study. The responses of land cover changes on the peak flow and runoff volume were investigated using 10 days of hourly rainfall events from 20 December to the end of December 2014 at the study area. The usage of two hydrological models defined that the changes in land use/land cover caused momentous changes in hydrological response towards water flow. The outcomes also revealed that the increase of severe water flow at the study area is a function of urbanisation and deforestation, particularly in the conversion of the forest area to the less canopy coverage, for example, oil palm, mixed agriculture and rubber. The monsoon season floods and runoff escalate in the cleared land or low-density vegetation area, while the normal flow gets the contribution from interflow generated from secondary jungle and forested areas.     

Maturity modeling and burial history reconstruction for Garau and Sargelu formations in Lurestan basin,south Iran

The Upper Jurassic Sargelu and the Cretaceous Garau formations are important source rocks in the Lurestan basin, southwest Iran. In this study, the maturity evolution and burial history of these source rocks are investigated using 1D modeling in 15 wells within the Lurestan basin. These models are calibrated using temperature and vitrinite reflectance readings at well locations. Results indicate that thermal maturity of studied source rocks increases towards the northwest of the Lurestan basin and is the lowest over the Anaran High. The present-day level of maturity suggests that these formations are suitable candidates for shale gas resources in the Lurestan basin.     

Spatiotemporal relation of RADAR-derived land subsidence with groundwater and seismicity in Semnan—Iran

Natural Hazards - Due to excessive harvesting of underground water resources in many important aquifers inside Iran, ground subsidence is occurring at different speeds. In present study, InSAR...     

Microtopography,water storage and flow patterns in a fine‐textured soil under agricultural use

Agricultural use of soils implies tillage and often compaction and therefore influences processes on soil surface and affects infiltration of water into the subsoil. Although many studies on soil surface processes or flow patterns in soils exist, works relating both are rare in literature. We did two tracer experiments with Brilliant Blue FCF on a tilled and compacted plot and a non‐tilled one to investigate water storage on the soil surface during simulated rainfall and changes of soil microtopography, to analyse the associated flow patterns in the soil and to relate both to tillage and compaction. Our results show that storage was larger on the tilled and compacted plot than on the non‐tilled one. After tillage, transport processes above the plough pan were partly disconnected from those underneath because macropores were disrupted and buried by the tillage operation. However, preferential flow along cracks occurred on both plots and the macropores buried below the tillage pan still functioned as preferential flow paths. Therefore, we conclude that the studied soil is susceptible to deep vertical solute propagation at dry conditions when cracks are open, irrespective of tillage and compaction. Copyright © 2012 John Wiley & Sons, Ltd.     

Comparison of two intelligent models to estimate the instantaneous global solar radiation in semi-arid climate conditions: Application in Iran

Solar radiation incident on the earth’s surface is a fundamental input for many aspects of climatology, hydrology, biology, and architecture. In addition, it is an important parameter in solar energy applications. Due to the high cost of the measuring instruments of solar radiation, many researchers have suggested different empirical methods to estimate this essential parameter. In this study, with the help of fuzzy systems and neural networks, two models have been designed to estimate the instantaneous global solar radiation in Rafsanjan city which has a typical climatic conditions of semi-arid region of middle eastern countries. In fuzzy and neural network model, the inputs are the number of the given day in the year, time, ambient temperature and cloudiness, The comparison between the results of the models and the measurements, shows that the estimated global radiation is similar to the measurement; for fuzzy model, statistical indicators RMSE, MBE and t-test are 103.4367 \((\hbox {w/m}^{2})\), 4.1169 \((\hbox {w/m}^{2})\) and 9.1318, respectively and for ANN, they are 85.46 \((\hbox {w/m}^{2})\), 3.08 \((\hbox {w/m}^{2})\) and 5.41, respectively. As the results indicate, both models are able to estimate the amount of radiation well, while the neural network has a higher accuracy. The output of the modes for six other cities of Iran, with similar climate conditions, also proves the ability of the proposed models.