Thesis Abstract

Soil compressibility is a critical parameter in geotechnical engineering that influences the stability and settlement behavior of structures built on or within the ground. Understanding the compressibility properties of soil is essential for designing safe and cost-effective infrastructure projects. This research project aims to investigate the compressibility properties of different types of soil through a comprehensive laboratory testing program. The research will focus on evaluating the compressibility characteristics of cohesive soils, such as clays and silts, as well as cohesionless soils, including sands and gravels. Various laboratory tests will be conducted to assess the soil's compressibility under different loading conditions. The primary tests will include oedometer tests, consolidation tests, and direct shear tests to measure the soil's deformation and strength properties. The oedometer tests will be conducted to determine the soil's consolidation behavior under vertical loading. By applying incremental loads to soil samples in oedometers, the researchers will be able to quantify the soil's compressibility, void ratio, and consolidation settlement characteristics. These tests will provide valuable insights into the time-dependent behavior of soils under load. Consolidation tests will be performed to analyze the soil's stress-strain behavior and estimate parameters such as the coefficient of consolidation and the compression index. These tests will help in predicting the settlement of structures founded on soil and assessing the time required for full consolidation to occur. Direct shear tests will be carried out to evaluate the shear strength and deformation properties of the soil. By applying horizontal shear stresses to soil samples, the researchers will be able to determine the soil's shear strength parameters, such as cohesion and internal friction angle. These parameters are crucial for assessing the stability of slopes and foundations. The research project will also investigate the influence of factors such as soil composition, moisture content, and loading conditions on the compressibility properties of soil. By studying the effects of these factors, the researchers aim to develop empirical correlations and predictive models to estimate the compressibility characteristics of different types of soil. Overall, this research project will contribute to the understanding of soil compressibility properties and provide valuable insights for geotechnical engineers and designers working on infrastructure projects. The findings from this study can help in improving the accuracy of soil behavior predictions and enhancing the safety and performance of civil engineering structures.

Thesis Overview

INTRODUCTION

Maryland is located in Enugu South in Enugu State. The subsoil of this region consists of fine grained soils with a considerable part of soft soil deposit which extends to a considerable depth.

      When a compressive load is applied to a soil mass, the volume of the soil mass tends to reduce, due to reduction in its voids. This reduction in volume of a soil mass on application of a compressive stress can rather be placed either normally (laterally), or vertically or in both directions depending on how the soil mass is allowed to deform. When a vertical compression deformation is non-uniform it poses serious danger to the safety of structures and other civil engineering facilities, therefore there is need to study the compressibility properties of soil in Maryland.

1.1.1 COMPRESSIBILITY

      This is the degree to which a soil mass decreases in volume when supporting a load.  Compressibility is reduced in a situation where there are more coarse-grained soils in contact with each other. It increases as the proportion of small particles increases and becomes highest in fine-grained soils which contain organic matter.

      Compressibility is approximately proportional to the plastic index. The greater the plastic index (PI), the greater the compressibility of the soil. (Adeyemi 2014).

1.1.2     PLASTICITY INDEX

This can be defined as the numerical difference between the liquid limit and plastic limit. The plasticity index is expressed in percentage of the dry weight of the soil sample and also it shows the size of range of the moisture contents at which the soil remains plastic.

      The plasticity index also gives a good indication of compressibility. The greater the plastic limit the greater the soil compressibility (Ashworth 1966).

1.2 AIMS AND OBJECTIVES

      The aims and objectives of this project includes

i.            To study compressibility

ii.           To obtain the compressibility properties of soil in Maryland area.

iii.         To obtain data that may be used in predicting the rate and the amount of settlement of structures in the area.

1.3 SCOPE OF STUDY

The scope of this project is limited to obtaining the compressibility properties of soil in Maryland area.

1.4 SIGNIFICANCE OF THE STUDY

    i.        This project will help to understand the compressibility properties of soil in Maryland area which will reduce the problems that geotechnical engineers face in designing economic foundation for the required infrastructure in Maryland area.

   ii.        The compressibility properties of the soil in the area obtained from labouratory test might be used to estimate the magnitude and the rate of settlement of a structure or an earth fill in Maryland area.

1.5 COMPRESSIBILITY PARAMETERS:

To obtain the compressibility properties of soil in Maryland, labouratory test will be carried out to obtain.

i.            Coefficient of compression/compression index (CC).

ii.           Swell index (CS)

iii.         Coefficient of compressibility (AV)

iv.         Coefficient of volume compressibility (MV)