Geological, geotechnical, and GPR investigations along the Mansa Devi hill-bypass (MDHB) Road, Uttarakhand, India
- PDF / 20,274,109 Bytes
- 15 Pages / 595.276 x 790.866 pts Page_size
- 25 Downloads / 389 Views
Ruchika Sharma Tandon I Vikram Gupta I Bhimala Venkateshwarlu
Geological, geotechnical, and GPR investigations along the Mansa Devi hill-bypass (MDHB) Road, Uttarakhand, India
Abstract In the present work, geological, geotechnical, and ground penetration radar studies were carried out along the Mansa Devi hill bypass (MDHB) road Uttarakhand, India in order to assess the slope instability conditions. Seven unstable zones along the entire MDHB road were identified which are prone to landslides. Geologically, the area is composed of mudstone and sandstone with thick overburden constituting sandy soil. The laboratory tests were carried out in order to evaluate the geomechanical characterization of soil, sandstone, and mudstone that constitute the slopes. The laboratory tests reveal that the slope is comprised of soil characterized by high permeability and low strength values. The soil is mainly sandy and non-cohesive. The laboratory tests on sandstone reveal that fresh sandstone exhibits exceptionally higher value of unconfined compressive strength (> 100 MPa) than the weathered sandstone (< 35 MPa). The mudstone is non-durable and contains considerable amount of expanded clay minerals which has a tendency to expand in the presence of water. It can weather easily and facilitate instability at shallow depth. A ground penetrating radar survey confirmed that the road is unstable particularly on those spots where the road either lying over mudstone beds or over thick non-cohesive sandy soil. The infiltration rate of water in this sandy soil is generally rapid which allows fast flow of water into the deeper horizons and thus cracks can be seen in road caused by vertical settlement. Similar results are observed in slope stability analysis where the slope covered with sandy soil exhibits factor of safety less than 1.0. However factor of safety is close to 1 where the slopes consist of alternate beds of sandstone and mudstone. Keywords Ground-penetrating radar . Sandstone . Mudstone . Sandy soil . Geotechnical properties . Slope stability analysis Introduction Landslides are one of the most serious geological hazards that can occur both in soil and rocks and cause substantial economical and environmental losses throughout the world. Landslides can be caused by natural factors, like fluctuation in ground water level because of varying rainfall, weathering, frost action, tectonic activities, etc., or anthropogenic factors, like change in slope geometry during construction of roads, tunnels, and bridges. (Homoud et al. 1997; Avanzi et al. 2004; Collins 2008; Evans et al. 2009; Zhou et al. 2010; Tang et al. 2011; Sorbino and Nicotera 2013; Cho 2017; Laimer 2017; Luo et al. 2018; Rosone et al. 2018; Bicocchi et al. 2019; Del Soldato et al. 2019; Rezaei et al. 2019). Both these factors act together on the slopes, and most of the times it becomes difficult to assess the prominent factor causing instability in an area. Thus, an integrated study of the geological, geomorphological, and geotechnical parameters is warranted in order to
Data Loading...
