Thesis Abstract and Dissertation Abstracts
Slope Stability Studies Along Karnaprayag - Gwaldam Road, Garhwal Himalaya, Uttaranchal, India
Abstract Category: Science
Course / Degree: D.Phil.
Institution / University: H.N.B.Garhwal University, Srinagar, Garhwal, Uttarakhand, India, India
Published in: 2008
In hilly terrains, roads constitute a major communication link with inaccessible areas. Unplanned excavations for construction of roads lead to the creation of unstable cut slopes which, along with various other adverse geological conditions, cause their failure creating damages to life and property. Uttarakhand is comparatively a new state in the fragile Himalayan terrain of India. Since its formation in 2000, there is a rapid surge of road construction in this hill state. The economy of this state is mainly tourism based and so more emphasis should be given on road networks. Therefore, a sound geological and geotechnical evaluation of hill slopes in the state is essential prior to construction of roads. Besides, it is also necessary to carry out a fast appraisal of the existing roads especially in the vulnerable sections. This exercise would be of immense importance towards identification of hill slopes prone to slope failures and landslides. In the present work slope stability studies along Karnaprayag - Gwaldam road stretch was carried out. A brief account of the chapters of the thesis is given below.
The first chapter deals with the general introduction and outlines the objectives of present research work. The chapter deals with the study area i.e. Karnaprayag -Gwaldam road stretch in Chamoli district of Uttarakhand state. The importance of this road stretch is highlighted in this chapter. The location and accessibility of this important hill route is outlined. The road stretch forms a part of Pinder river valley in Uttarakhand Himalaya. This road stretch is taken for slope stability studies in both rock and soil slopes. In this chapter, the physiography and drainage, climate, vegetation and seismicity of the study area are also discussed. In addition, this chapter also outlines the previous work carried out in the area and also the possible outcome of the present work.
The second chapter deals with the geological setting of the area. In this chapter the regional geological framework of the area is discussed in brief. In addition, the geology along the study area i.e. Karnaprayag - Gwaldam road stretch is discussed.
The third chapter deals with the Approach and Methodology followed for the present work. In this chapter discussion on rock classifications is given. In addition, a detailed account of Rock Mass Rating (RMR) is given. A general introduction to stability of hill slopes and factor of safety (F), and modes of failures in rock and soils is given. Besides, a detailed account of the methods used for stability studies in both, rock and soil slopes are also given. For stability studies in rock slopes modified Slope Mass Rating (SMR) system [Anbalagan et al., 1992 & BIS Code No. IS 13365 (Part 3): 1997] is used which is an empirical technique. This system is explained in detail in this chapter. For the detailed slope stability of hazardous rock slopes, relevant analytical methods can be used to assess their status of stability. The relevant analytical methods for planar and wedge mode of failure are discussed. Moreover, a brief account of conditions of Toppling failure is also given. For detailed slope stability assessment of slopes in soils/ overburden debris, a detailed account of the relevant analytical methods is given for circular failure and planar debris slide/ talus failure.
The fourth chapter deals with slope stability studies which have been carried out along Karnaprayag - Gwaldam road stretch. To assess the stability of rock slopes, Slope Mass Rating (SMR) technique was developed by Romana in 1985. SMR is, in fact, an application of Rock Mass Rating (RMR) scheme of Bieniawski (1979). It considers wedge failure as a special case of planar failure. Later it was modified by Anbalagan et al. (1992) to account for wedge failure as a separate type of failure. The cut slope stability studies of the entire Karnaprayag - Gwaldam road stretch was carried out using modified SMR approach [Anbalagan et al., 1992 & BIS Code No. IS 13365 (Part 3): 1997]. This approach is one of the most efficient techniques to study the conditions of hill slopes from their stability point of view. For preliminary and fast assessment, the modified SMR approach is considered appropriate. The present work is an attempt to analyse some potentially unstable slopes along the 66km long Karnaprayag - Gwaldam road stretch in Chamoli district of Uttarakhand state. The main reason for selecting Karnaprayag - Gwaldam road stretch is that it is the only road in upper hills connecting the two physiographic divisions of Uttarakhand viz. Garhwal and Kumaun. Any disruption along this important hill route affects the state economy in many ways. Therefore, it is important to carry out slope stability studies along the entire route.
In the present work “Whole to part” approach has been used. Traverses have been taken along the entire Karnaprayag - Gwaldam road to identify slopes vulnerable to landslide hazards by using modified SMR approach. Based on this approach, SMR values have been obtained for selected slopes. Later the slopes were categorized into different SMR classes. In addition, Harmony and Narayanbagar landslides, which are the major landslides along this important road stretch, were chosen for detailed studies. Detailed investigations were carried out for these two landslides.
The fifth chapter deals with the detailed slope stability studies of selected slopes, both in rocks and in soils/ overburden. Stability analysis was carried out to calculate factor of safety (F) values for few rock slopes falling in hazardous SMR classes (class IV & V) by using relevant analytical work. In addition, detailed slope stability assessment was carried out for Harmony and Narayanbagar landslides, which are the two major landslides in soils/ overburden debris along this important hill route. The stability analysis of Harmony landslide was carried out using Circular Faliure Charts method and Bishop’s simplified method of slices. The stability analysis of Narayanbagar landslide was carried out for static and dynamic condition.
The sixth chapter deals with the discussions of stability analysis of rock and soil slopes as explained in chapter 6. In all, 32 locations were selected along Karnaprayag - Gwaldam road stretch to carry out SMR studies for identifying potential unstable rock cut slopes. It was observed that mainly planar and wedge mode of rock slope failures are present along this important road stretch. The selected locations, after carrying out SMR studies, were categorized into different SMR classes (Class I to V). In all, 10 locations were falling in hazardous SMR classes (Class IV & V). The factor of safety (F) values obtained by detailed stability analysis of Harmony and Narayanbagar landslides (as discussed in chapter 6) indicate that both of these landslides are presently in just stable condition.
Control measures were suggested for rock and soil slopes along this important hill road stretch. For the rock slopes falling in hazardous SMR classes (Class IV & V), corrective measures (supports for SMR classes) were suggested. In addition, a set of control measures were also suggested for Harmony and Narayanbagar landslides.
The seventh and last chapter comprises the concluding remarks of the present work. In this chapter, all aspects of present work, as discussed in previous 6 chapters are outlined in brief. The chapter outlines the fact the road construction should always be taken up after assessing the slope conditions and the required stability measures should be carried out immediately after the construction without delay, because if any instability of the slopes occur then the remedial measures are extensive and costlier.
Thesis Keywords/Search Tags:
Slope Stability, Garhwal Himalaya, India
This Thesis Abstract may be cited as follows:
Kohli, A. (2008): Slope Stability Studies Along Karnaprayag Gwaldam Road, Garhwal Himalaya, Uttarakhand, India; Unpub. D.Phil. Thesis, Department of Geology, H.N.B.Garhwal University, Srinagar, Garhwal, Uttarakhand, India.
Submission Details: Thesis Abstract submitted by Dr. Atul Kohli from India on 15-Jan-2011 04:17.
Abstract has been viewed 4254 times (since 7 Mar 2010).
Dr. Atul Kohli Contact Details: Email: atul_kohli1@rediffmail.com
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