INVESTIGATION IN TO SOME OF INDEX AND ENGINEERING PROPERTIES OF RESIDUAL TROPICAL SOIL (IN WELENCHITI TOWN)

Abstract

Tropical residual soils are highly weathered and altered soils formed by the in-situ weathering and decomposition of rocks in the tropical and sub-tropical regions with hot, humid climatic conditions. There is no any soil investigation that done in Welenchiti town before this investigation, it is the first. From sit investigation, the majority of soil in this town is tropical residual soil. Know this investigation work; some peculiar geotechnical characteristics of soil that have been investigated on index and engineering properties of soils sampled from different part of welenchiti town which also tropical area. The aim of this thesis is to provide in-depth engineering and index properties of Welenchity town. Welenchity one of the boset worda town which is developing rapidly. Rapid urbanization in the city area has led to an increased interest in the engineering behavior of the soils, which are present within the city area. Geotechnical information of the subsoil in an urban area is important for various civil engineering works. Non-availability of the proper geotechnical information of the subsoil makes foundation and engineering works expensive, difficult and sometimes hazardous. A total of 24 bulk samples were taken, batched in to three and subjected to Air and Oven drying. Thereafter, index properties such as moisture content, sieve analysis, Atterberg limits, specific gravity, free swell, unconfined compression test and one dimensional consolidation characteristics of the soil were evaluated. In the analysis of Atterberg Limits, in majority of the soils difference was observed between the Atterberg Limits obtained from test on a specimen mixed for 5min and that of 30min, air and oven dry this indicates that the cementation of the clay particles is to be disaggregated with higher mixing time. Soil classification using Unified Soil Classification System (USCS) and AASHTO Classification Systems, According to the USCS; chart the soils under investigation falls in the MH zone, which means that the soils have ‘poor’ engineering properties that are considered unsuitable for various engineering purposes. However, the AASHTO Classification System classify majority of the soils under sub group A-7-5 with a group index greater than 4, which mean the soils are poor sub grades and embankments construction materials.