Paraphrase

Introduction

In this experiment our goal is to determine the compressive strength of cohesive soil in its undisturbed state. Furthermore, we are responsible to obtain the compressive strength in order to calculate the unconsolidated un-drained shear strength by using a strain-controlled application of an axial load.

Theory

The resistance against deformation caused by applying a shear load force which introduces a failure along a plane, is defined as the shear strength. For soils to determine the shear strength we use the compressive stress test. Moreover, The shear strength is denoted by (So). In this test there is a possibility for it to be stress controlled or strain controlled. The strain-controlled test is a test that is widely used due to its simplicity, as it requires a simple loading mechanism. On the other hand, the stress controlled test is a method used seldom as the load applied can result in a erratic strain response.

Procedure

1. We have to obtain a undisturbed sample of soil, provided by the lab technician.

2. The sample should be peeled from the wax surrounding it and placed at the appropriate location on the loading machine.

3. The edges of the sample should be then trimmed of using the proper cutting tool.

4. The trims obtained are kept in order to test for water content.

5. Once trimming the edges have been complete, the load can be now applied until failure.

6. While the load is being applied, one should record the reading of load and deformation at specified intervals.

Discussion

From the plot of compressive stress versus axial strain, the unconfined compressive strength is determined as the maximum value of the compressive stress or the compressive stress at 15 % axial strain and found to be unknown. Similarly, the shear strength is calculated as half of the unconfined compressive strength, which is 27 kN/m2.

In conclusion, the test results provide are an estimate of the relative consistency of the soil. It is used in almost all geotechnical engineering designs (e.g. design and stability of foundations and retaining walls.) to obtain a rough estimate of the soil strength and construction techniques