Stability analysis of multi-directional anchored rock slope subjected to surcharge and seismic loads

More than one set of anchors with different orientations can be an economical solution to completely stabilize the rock slope. In this note, a general analytical expression for the factor of safety of a multi-directional anchored rock slope (MDARS) against plane failure is derived, incorporating most of the practically occurring destabilizing forces under surcharge and seismic loading conditions. Several special cases of this expression are found to be similar to those reported in the literature. A graphical presentation shows that for any specific inclination of one set of anchors to the normal at failure plane, the variation in the inclination of the second set of anchors to the normal at failure plane, when greater than approximately 60°, does not cause a significant change in the factor of safety of the MDARS.     

Three dimensional velocity structure of the Koyna-Warna region using local earthquake tomography

A dense seismic network (～100 stations) was operated in the Koyna-Warna region from January 2010 to May 2010, that allow us to collect 400 high-quality local earthquake data of magnitude less than 4. In this region, the fault structure and tectonic setting that accommodate the induced seismicity is not well understood. To investigate the seismotectonics of the region, we have inverted 7826 P- and 7047 S-P arrival times for 3-D Vp and Vp/Vs tomographic models along with hypocenters parameters in the region. Although, Dixit et al. (2014) have performed 3-D local earthquake tomography with double-difference tomography code using catalog differential time data. In this paper, Simulps14 code on the same data set is applied. For better approach P arrival time and S-P travel times are inverted directly for Vp, Vp/Vs variations and earthquake locations. High Vp ～5.9 to 6.5 and low to high Vp/Vs ～1.69-1.74 imaged in the hypocenter region. These features interpreted as a fluid bearing rock mass under high pore pressure. It is also observed that below the trap basement form a local topography depression between the Koyna and Warna Reservoirs. To the South of the Warna reservoir, intense seismic activity defines a major cluster of ～ 5 km width at 3 to7 km deep, located under the trap, where the basement is deepening. Such regions are inferred to be associated with the seismically active faults zones. The obtain velocity anomalies are reliable down to a depth of 10 km. This is also confirmed by the analysis of three resolution parameters viz. Hit count, Derivative Weight sum (DWS) and Resolution Diagonal Elements (RDE).     

Evaluation of geotechnical properties of overburden dump for better reclamation success in mining areas

Coal-mining activities are precursors to land degradation, a part of which is directly related to the generation of huge quantity of overburden (OB) material. The problem of managing OB is mitigated through reclamation, which is directly associated with the geotechnical properties of these dumps. The main objective of this study was to assess the potential of an alternative management plan of OB by analyzing physical properties of these dumps. This alternative management plan of OB could enhance reclamation success by fostering conditions conducive for vegetation growth. This is especially required in old mining areas, where salvaging of topsoil was not done, and as a result, reclamation was affected. For the present study, 12 representative OB samples were collected from two open-cast coal mines (OCP-A and OCP-B) of Bastacolla area in Jharia Coalfield, Dhanbad, India. The samples were analyzed for different geotechnical properties. The results revealed that optimization of these parameters could help in enhancing the reclamation success of the area. From land-use classification, it was observed that about 242 ha of the study area was OB dump; if these areas are reclaimed successfully, then they can act as a potential source of carbon sequestration, and furthermore, they will improve the esthetics and the overall environmental quality at these degraded areas.     

Behavioral of sediment transport at lowland and mountainous rivers: a special reference to selected Malaysian rivers

Mountain rivers and lowland rivers differ in many ways. Some of the many elements that distinguish both river systems apart are the rivers’ geomorphological appearances, hydraulic geometry, pollution transport, sediment transport, and its own roughness and coarseness. In this particular study, the element of sediment transport is given distinctive attention too. This study employs the deterministic approach for bed load prediction entailing the use of the parameterization concept where particle size and flow variation is taken into full consideration. Apart from that, the classical approach of Shields number is also used to determine the transport rates at the fluvial system. However, due to some limitation and range of applicability, the Shields number approach was re-modified to suit the range of applicability. Changes were made to the alleviating critical stress term and formulating exponential approach. For this research, it was important to deduce the underlying principles which are universal and common to all river systems, due to obvious and distinct differences between the mountain and lowland rivers. A special attribute was given to the Malaysian natural rivers because of the limited recorded data available. All datasets were compiled and tested with the bed load predictors to observe the commonality pattern between the lowland and mountain river systems. Most of the bed load transport equations limit the range of applicability by isolating the flow regime or bed roughness individually. Thus, it was vital for researchers to find the commonality pattern between these two river systems which needed to be statistically sound in its form. It was postulated that the particle densimetric Froude number is graphically and statistically fit for both river systems. Hence, this predictor is used as it has a high potential to be included in the sediment transport parameterization for Malaysian natural rivers.     

Chemical weathering of the Indo-Gangetic alluvium with special reference to release of fluoride in the groundwater,Unnao district,Uttar Pradesh

In the central part of Indo-Gangetic alluvium in the Unnao district, Uttar Pradesh there are many pockets where groundwater shows high fluoride content. Drinking of fluorinated ground water has effected a large population and in many villages more than 80% of the population is suffering from fluorosis. The source of this fluoride appears to be the alluvial sediments deposited in the geological past as no hard rock terrain is present in the nearby areas. The area is dominantly made up of mud with pockets of sand. The sand fraction is made up of quartz, plagioclase, microcline, muscovite and biotite along with some accessory minerals like garnet, epidote, chlorite, tourmaline, hornblende, kyanite and a few opaque minerals. Moreover, the fluoride content in the groundwater varies both spatially and with depth indicating a sporadic occurrence. The surface water is devoid of high content of fluoride but is reported in hand pumps and in the dug wells. This paper deals with the geochemical study of the sediments up to a depth of 45m as most of the hand pumps are up to this depth to understand the source of fluoride. ¹⁴C dates of calcretes have suggested that the 45 m thick succession must have been formed in about 45000 years.     

Laboratory model tests for cyclic load-induced settlement of a strip foundation on a clayey soil

Laboratory model test results are presented for the cyclic load-induced settlement of a strip foundation supported by a saturated clayey soil. In performing the tests, the foundation was initially subjected to an allowable static load, after which a cyclic load with a frequency of one cycle per second was superimposed on it. The magnitudes of the static load and the amplitude of the cyclic load were varied. Based on the model test results, relationships for the foundation settlement and intensities of the static and cyclic loads are presented.     

Occurrence of High Level Magma Intrusives and Associated Mineralization near Gani Inlier,Kurnool Sub-Basin,Cuddapah Basin,India

An ensemble of spatially associated high level magma intrusives comprising dykes, laccolith and vent have been identified near Gani inlier in the Kurnool sub-basin. Geological setting, morphology of igneous intrusives and their relationships with the sediment cover have been documented. Diabase in laccolith, dykes and vesicular basalt in vents are prominent rocks and have been subjected to extensive deuteric alterations viz. saussurtisation and uralitisation. It is envisioned that the basic magma was intruded as dykes in strike-slip fault domain, outpoured through the vents as vesicular basalts at the intersection zones of cross faults. The vertical ascending melt was deflected as a sheet due to fault control at a sub-surface level of ～700m along the lithological discontinuities in country rock sediments. The sheet to laccolith transition has resulted in the uplift of older Tadpatri Formation as an inlier amidst the Neoproterozoic Kurnool sediment cover. The localization of iron ore and copper mineralization adjacent to intrusives is attributed to late stage melt-fluid activity associated with the igneous activity. Based on field relationships it is suggested that the high level magmatic activity had occurred after the Kurnool sedimentation in this part of the Kurnool sub-basin.