A Study Of Settlement Using Tangent Modulus Approach In The Case Of Bishoftu Town

Abstract

The estimation of settlement often receives less attention than they deserve, with the result that excessive settlements cause far more problem of structural failure. Settlement analysis was therefore one of the most important types of analysis made by soil engineer for designing safe and economical structures. The main aim of this research work focuses on developing and promoting the concept of tangent modulus in the field of soil compressibility in case of Bishoftu town. The classical approach, which is widely used in our country and other parts of the world, has limitations. These limitations have contributed for the development of the tangent modulus approach. The tangent modulus approach provides better way of determining settlement for various types of soil ranging from hard to very soft soil. In the method the soil property, which is determined from laboratory soil deformation tests, are used. In the approach a compression modulus also called the constrained modulus, the tangent to a linear plot of stress versus strain curves determined from laboratory tests play a significant role. It is emphasized on this property of the soil, as it is a measure of resistance of the soil against deformation due to change in loading condition the compression modulus, measures of the resistance of a media or an isolated part of it against a forced change of equilibrium condition. From the computation of settlement results, it has been observed that the effective stress is 31.41KN/m2 and the total stress is 131.23 KN/m2. Also, it has been observed that the compressibility value of soil in classical approach is 8.46cm and in tangent modulus approach is 10.05cm. The Therefore, the simplicity and rationally inherent in the tangent modulus concept made it the preferred method of analysis of the compressibility of soil. It has been shown herein that the tangent modulus concept which has a good scientific explanation is applicable for Bishoftu soil to compute compressibility