Investigation of Soil at Different Locations of the Kathmandu Valley of Nepal

Abstract

Investigation of soil bearing capacity helps in determining the design of the foundation of any structure. The main parameters which are commonly associated with the determination of liquefaction potential are the saturated sand and silty soils. Therefore, the present study was focused on the investigation of soil bearing capacity at different locations of Kathmandu valley of Nepal. The study was conducted during the period of 2019. Laboratory tests of the soil is the major tool of the investigation. The findings were analyzed in five categories emphasizing on bearing capacity, bulk density, natural moisture content, specific gravity and grain sieve analysis. The study found that the soil bearing capacity of the Kathmandu valley is low. Most of the places consist of Silty Clay soil, the consistency of which is very low. The study found that the highest and lowest value of bearing capacity was to be 151.2Kn/m² and 61.66Kn/m² respectively in Lalitpur District. Similarly, the highest and lowest value of bearing capacity of Kathmandu was found to be 163 Kn/m² and 58.6 Kn/m², whereas the same parameter in Bhaktapur, was found to be 6 Kn/m² and 56.4 Kn/m². Furthermore, the highest and lowest value of bulk density of the Lalitpur district was found to be 1.72 gm/cm³ and 2.1 gm/cm³ respectively, and for Bhaktapur it was declared to be 1.69 gm/cm³ and 2.01 gm/cm³ consecutively. In addition, the highest and lowest value of bulk density was calculated to be 1.55 gm/cm³ and 2.09 gm/cm³ for Kathmandu. Whereas, based on natural moisture content, the findings which were observed are the highest and lowest value of 4.4% and 99.85% at Lalitpur; and at Bhaktapur 10.72%, 75.95% respectively. Similarly, the highest and lowest value of Kathmandu district was found to be 4.76% and 99.8%. Moreover, based on specific gravity the highest and lowest values of Lalitpur District are 2.71 and 2.55, and at Bhaktapur district are 2.72 and 2.55, and at Kathmandu district are 2.72 and 2.55 respectively. Thus, the consistency of the soil at most of the places of the Kathmandu Valley ranges from soft to medium soft depending upon the value of N (i.e. 4 to 8). The study would like to suggest that the geotechnical investigation is necessary before the construction of a building in Kathmandu valley. Furthermore, the depth of the foundation should be increased, raft foundation is recommended to a greater extent. And, pile foundation is recommended, where the soil has very low bearing capacity.