Geotechnical Studies along the Tinpiple Banchare Dada Road, Central Nepal

This paper describes about field study as well as laboratory test performed for the geotechnical properties of rock and soil along the Tinpiple-Banchare Dada road alignment. The purpose of the present study was to determine the geotechnical properties for both rocks and soils along the road alignment. Detailed geotechnical soil/rock field study sheets were used to record geotechnical parameters in the field and to know the site condition. Dynamic cone penetration test was performed in the in situ soil. Laboratory test were performed for the classification of the soil, and to determine the optimum moisture content. Results reveal that most part of the road is aligned through the completely weathered sandstone, its residual soil (classified as SM) along with the gneisses. The results of the Dynamic Cone Penetration Test show that minimum CBR % varies from 18% at 10 cm depth to 2% at 58 cm. These values of the CBR % are considered good so no capping is required. The results of the compaction test show that maximum dry density for most of the samples were obtained at 10-15 % optimum moisture content. The results of the joint analysis revealed that chainage 2+ 115, 2+475, 5+125 to 5+ 175 and 7+220 km has probability of lateral, lateral / central, central and central wedge failure respectively. Small landslides were initiated in upslope side due to road cutting and can be stabilized by simple bioengineering techniques. The results of this study are very important for the construction of a sound road and should be considered during the full phase onstruction of the road