Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

A. K. Awasthi ¹, B. Parkash ¹, B. B. S. Singhal ¹

Affiliations
1 University of Roorkee, Roorkee, IN

Abstract

Dispersal pattern of sandstones of the Jodhpur Formation around Bhopalgarh (Rajasthan) was studied by measuring dip azimuths of cross-bedding foresets. Variance components of paleocurrents due to various sources were analysed. Low variance of paleocurrents, profusely cross-bedded character of sandstones and mainly arenaceous nature of the formation, suggested that the deposition of the major part of the Jodhpur Formation took place under braided fluvial conditions.

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S. Parkash ¹, A. K. Awasthi ², N. S. Virdi ¹

Affiliations
1 Wadia Institute of Himalayan Geology, 33, G.M.S. Road, Dehra Dun - 248001, IN
2 Department of Earth Sciences, Indian Institute of Technology, Roorkee - 247 667, IN

Abstract

The stability of rock slopes along the highways is a major concern to the road maintenance agency as well as for the safety of those plying on these roads. Any kind of slope failure may lead to disruption in traffic, socio-economic activities, loss of property, injuries or sometimes even deaths of humans and/or livestock, and environmental degradation. Therefore, an assessment ofthe stability conditions along these highways is quite important. Though several techniques of slope stability analysis viz. boundary element method, finite element method, finite difference method, discriminant analysis etc. are available, yet the slope mass rating (SMR) technique has been found to be quite useful due to the ease with which it can be practiced, and its effectiveness in interpreting stability and recommending control measures. The technique is based on the well established rock mass rating (RMR) technique. The rock mass rating technique has been used earlier in many mining and engineering projects related to tunnels and underground structures.

SMR technique is a field based study which involves collection of data on rock types, their strength, quality, condition of discontinuities, spacing of discontinuities, orientation of discontinuities, ground water conditions and method of slope excavation etc Eight sites, selected on the basis of good exposures of the rock outcrops and the slopes that have been blasted or mechanically disturbed during road construction or at some later stage, were studied and analysed for their potential degree of stability using SMR approach. However, the type of probable failure and the direction of movement have been assessed on the basis of kinematic analysis. The kinematic method also helped in identifying the potentially unfavorable planes that could be involved in the movement. The results indicate that the technique can be usefully exploited for assessing the stability of rock slopes in the Himalayan terrain.

Keywords

Rock Slope Stability, SMR Technique, Discontinuity Planes, Kinematic Analysis, Uttaranchal.

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Tejpal Singh ¹, Umakant Sharma ², A. K. Awasthi ³, N. S. Virdi ⁴, Ravindra Kumar ²

Affiliations
1 CSIR-Centre for Mathematical Modelling and Computer Simulation, Bangalore - 560 037, IN
2 Department of Geology, Panjab University, Chandigarh - 160 014, IN
3 Department of Earth Sciences, Indian Institute of Technology Roorkee, Roorkee - 247 667, IN
4 Wadia Institute of Himalayan Geology, Dehradun – 248 001, IN

Abstract

Neotectonism in the Sub-Himalayan belt is not new. Moreover, the word 'Sub-Himalaya' is almost synonymous with 'neotectonic activity'. In the present paper, we report some of the most convincing geomorphic and structural evidences of neotectonic activity from the Sub-Himalayan belt in the Nahan Salient. The geomorphic evidences mainly include the four geomorphic surfaces identified from the transverse topographic profiles drawn parallel to the Himalayan front. These surfaces are commonly covered with terrace deposits that are tilted as well as faulted at a number of places. A number of faults, directly observable in the field, are normal in nature and they are oriented at high angles to the Himalayan Frontal Thrust (HFT). These faults are similar to the E-W extension in southern Tibet in response to the oblique convergence of India at ∼N20°E in the NW Himalaya. They are attributable to the kinematics of neotectonic compression along the HFT, the frontal ramp-oblique ramp-frontal ramp geometry of the thrust fault and related adjustments.

Keywords

Geomorphology, Neotectonics, Nahan Salient, Sub-Himalaya.

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