Distinct element simulation of ultimate bearing capacity in jointed rock foundations

In this paper, distinct element method numerical modeling is applied to evaluate bearing capacity of strip footing rested on anisotropic discontinuous rock mass. As yet, a little work has been carried out to investigate the effect of joint set orientation on the bearing capacity of rock mass. Generally, the overall behavior of rock mass under loading is very complicated and such analysis should include deformation determination, sliding along discontinuities and failure of rock material. Failure mechanism of rock mass depended on both geometrical parameters of joint sets and strength parameters of rock mass. In this research, it is assumed that rock mass contains one joint set, and therefore the anisotropy in bearing capacity and rock behavior is only due to the existence and orientation of the joint set. In this study, by assuming constant strength parameters and using Mohr–Coulomb failure criterion for the single joint set and nonlinear Hoek–Brown failure criterion for rock material, variation of the bearing capacity values and the type of failure mechanism of rock mass with different joint set dips is investigated. The obtained results indicate that the ultimate bearing capacity of rock mass containing one joint set varies between 27 and 86 % of intact rock.     

The plane symmetric vacuum solutions of modified field equations in metric f(R) gravity

The f(R) theories of gravity have been interested in recent years. A considerable amount of work has been devoted to the study of modified field equations with the assumption of constant Ricci scalar which may be zero or nonzero. In this paper, the exact vacuum solutions of plane symmetric spacetime are analyzed in f(R) theory of gravity. The modified field equations are studied not only for R=constant but also for general case R≠constant. In particular, we show that the Novotný-Horský and anti-de Sitter spacetimes are the exact solutions of the field equations with the non-zero constant Ricci scalar. Finally, the family of solutions with R≠constant is obtained explicitly which includes the Novotný-Horský, Kottler-Whittaker, Taub and conformally flat spacetimes.     

An investigation on the ground motion parameters and seismic response of underground structures

Peak ground acceleration (PGA), frequency content and time duration are three fundamental parameters of seismic loading. This study focuses on the seismic load frequency and its effect on the underground structures. Eight accelerograms regarding different occurred earthquakes that are scaled to an identical PGA and variation of ground motion parameters with ratio of peak ground velocity (PGV) to PGA, as a parameter related to the load frequency, are considered. Then, concrete lining response of a circular tunnel under various seismic conditions is evaluated analytically. In the next, seismic response of underground structure is assessed numerically using two different time histories. Finally, effects of incident load frequency and frequency ratio on the dynamic damping of geotechnical materials are discussed. Result of analyses show that specific energy of seismic loading with identical PGA is related to the seismic load frequency. Furthermore, incident load frequency and natural frequency of a system have influence on the wave attenuation and dynamic damping of the system.     

Water leakage paths in the Doosti Dam,Turkmenistan and Iran

The Doosti Dam, with a reservoir capacity of 1,250 million cubic meters, was constructed on the Harirood River at the border of Turkmenistan and Iran. The reservoir is in direct contact with permeable formations on the right abutment of the dam including the Neyzar Sandstone, the Kalat Limestone and the Pesteleigh alternative layers of marlstone and sandstone. After the reservoir impoundment, several new springs and seepages emerged from these formations and the alluvium. The amount of leakage increased with the rise in reservoir water level. Fifteen kilograms of sodium fluorescein were injected into a 113-m deep borehole intersecting three permeable sandstone layers of the Pesteleigh formation. Dye was detected downstream of the grout curtain in boreholes and springs that were in direct contact with parts of the Pesteleigh formation having the same sandstone layers as the injection borehole. The dye velocity was in the range of diffuse flow, confirming the good performance of the grout curtain in the Pesteleigh formation. No dye was detected in the other formations because the injection borehole was not in direct contact with these formations. The hydraulic relation of the other formations with the reservoir was determined by considering direct contact of the formations with the reservoir, emergence of new springs and seepages after reservoir impoundment, correlation of time variations of the springs discharge and the borehole’s water level with the reservoir water level, and in some cases the hydrochemistry of the water. The results show that the Kalat and Neyzar formations are hydraulically connected to the reservoir, but the small amounts of leakage from these formations at a hydraulic gradient of 24% indicates good performance of the built grout curtain. The total reservoir leakage at maximum reservoir water level was 100 l/s which is insignificant compared with the 15 m³/s average annual release of the reservoir.     

Shoreline spatial and temporal response to natural and human effects in Boujagh National Park,Iran

Shoreline variation and river deltas are among the most dynamic systems in marine environments. The related different variations in spatial and temporal scales play significant roles in land planning and different management applications. Modeling the dynamics of seashore of Boujagh National Park (BNP) which is located on the southern coast of the Caspian Sea in the Sefidrud Delta (SD), considering natural and anthropogenic factors, was the main objective of the current study. To achieve this goal, a combination of remote sensing data, historical data, and numerical simulations was utilized. The BNP covers an area of 3,270 ha and includes two international wetlands, Boujagh and Kiashahr. In earlier periods, this area faced severe morphological changes whereas recently its shoreline has experienced gradual variations. Accordingly, at the first stage, the shoreline variation from 2006 to 2017 was extracted by processing and classifying Operational Land Imager (OLI) and Thematic Mapper (TM) images from Landsat satellites using the Maximum Likelihood approach. In the second stage, the two dimensional MIKE21 model was utilized to identify wave and coastal current patterns and parameters for the year 2015. Morphologically, the results showed that, the shoreline of the BNP is affected by several natural and anthropogenic factors. Seaward advancement of the shoreline occurred in zones A (east zone) and C (west zone) due to Caspian Sea Level drop and sedimentation while retreating occurred at Zone B (north zone) influenced by wave and current patterns and reduction of the Sefidrud River flows. Also, the results imply that maintaining the existing conditions results in the disappearance of a considerable part of the ecological area in the BNP. Hence, to manage and preserve the coastline of the BNP complying with the current anthropogenic and natural factors, it is vital to take necessary management measures.     

Application of Landsat-8 and ASTER satellite remote sensing data for porphyry copper exploration: a case study from Shahr-e-Babak,Kerman, south of Iran

Abstract

The Shahr-e-Babak region located in the Kerman metallogenic belt is one of the high potential segments of Urumieh–Dokhtar magmatic arc for porphyry copper and epithermal gold mineralization in the south of Iran. This high potential zone encompasses several porphyry copper deposits under exploitation, development and exploration stages. The aim of this study is to evaluate Landsat-8 data and comparison with the Advanced Spaceborne Thermal Emission and Reflection Radiometer data-sets for mapping hydrothermal alteration zones related to Cenozoic magmatic intrusions in Shahr-e-Babak region. Previous studies have proven the robust application of ASTER in lithological mapping and mineral exploration; nonetheless, the Landsat-8 data have high capability to map and detect hydrothermal alteration zones associated with porphyry copper and epithermal gold mineralization. In this investigation, several band combinations and multiplications, developed selective principal component analysis and image transformations were developed for discriminating hydrothermal alteration zones associated with porphyry copper mineralization using Landsat-8 data.     

GIS integration of hydrogeological and geoelectrical data for groundwater potential modeling in the western part of greater Kushtia district of Bangladesh

Geographical Information System (GIS) has been used in this paper to delineate groundwater resources potential in the western part of greater Kushtia district of Bangladesh, where urgent attention for augmentation of irrigation water supply is required. Thematic maps of transmissivity, hydraulic conductivity, specific yield, net recharge, aquifer thickness, surface water bodies, aquifer resistivity, overburden aquitard thickness and its resistivity have been prepared and assigned weight according to their relative importance using Analytical Hierarchical Process for the preparation of groundwater potential model. Since the values within each thematic map vary significantly, they are classified into various ranges or types and assigned ratings. Finally, the thematic maps are integrated using GIS to prepare the groundwater potential map for the study area in terms of Ground Water Potential Index (GWPI). The evolved map indicates that 22.51% of the study area have GWPI more than 0.70 and therefore, have excellent prospective for exploitation. About 69.12% of the area with GWPI ranging from 0.50 to 0.70 is also quite promising for groundwater abstraction, while the rest 8.37% area having GWPI below 0.50 indicates moderate potential. The obtained map of groundwater potential is found in good agreement with the yields of available pumping test data.     

Deriving preference order of post-mining land-uses through MLSA framework: application of an outranking technique

This study intends to take advantage of a previously developed framework for mined land suitability analysis (MLSA) consisted of economical, social, technical and mine site factors to achieve a partial and also a complete pre-order of feasible post-mining land-uses. Analysis by an outranking multi-attribute decision-making (MADM) technique, called PROMETHEE (preference ranking organization method for enrichment evaluation), was taken into consideration because of its clear advantages on the field of MLSA as compared with MADM ranking techniques. Application of the proposed approach on a mined land can be completed through some successive steps. First, performance of the MLSA attributes is scored locally by each individual decision maker (DM). Then the assigned performance scores are normalized and the deviation amplitudes of non-dominated alternatives are calculated. Weights of the attributes are calculated by another MADM technique namely, analytical hierarchy process (AHP) in a separate procedure. Using the Gaussian preference function beside the weights, the preference indexes of the land-use alternatives are obtained. Calculation of the outgoing and entering flows of the alternatives and one by one comparison of these values will lead to partial pre-order of them and calculation of the net flows, will lead to a ranked preference for each land-use. At the final step, utilizing the PROMETHEE group decision support system which incorporates judgments of all the DMs, a consensual ranking can be derived. In this paper, preference order of post-mining land-uses for a hypothetical mined land has been derived according to judgments of one DM to reveal applicability of the proposed approach.     

Early Cretaceous <Emphasis Type="Italic">Neotrocholina</Emphasis> Reichel, 1956 from the Tirgan Formation,Kopet Dagh sedimentary basin,NE Iran: systematic and biometric interpretation

Neotrocholina Reichel, 1956 is one of the most important benthic foraminifera in Early Cretaceous. Some of the species of this genus are indexes in biostratigraphy especially for this interval (e.g., Neotrocholina friburgensis: Late Barremian–Early Aptian; Neotrocholina aptiensis: Early Aptian). In order to conduct accurate paleontological investigations, sampling from the carbonate units of the Tirgan Formation in Kopet Dagh sedimentary basin is done. According to the occurrence level in the studied stratigraphic sections as well as biometric interpretations, two species of this genus (N. friburgensis and Neotrocholina valdensis) are pointed out.     

THREE-DIMENSIONAL GEO-MORPHOLOGICAL MODELLING OF ESTUARINE WATERS

1 INTRODUCTION Estuaries and coastal zones have been used as means of navigation, disposal of waste material, fishing and many commercial and economic activities over the centuries. One of the most important phenomena in these regions is the suspended sediment transport, which may cause erosion and deposition, and hence changes in the estuarys morphology. In turn, such changes may lead to problems relating to navigation and estuarine management. When the bed boundary of an estuary change…