Correlation between SPT and CPT

Abstract

The objectives of this thesis are to introduce and describe SPT, CPT methods and the correlation between them. Moreover, it is explained how the correlation between SPT and CPT is reliable and what kinds of studies are needed to improve the reliability of the correlation between qc/N and D50,

Standard Penetration Test (SPT) is internationally used in-situ test to investigate soil properties under the ground. However, it has problems regarding the repeatability and reliability even if geotechnical engineers have tried to standardize the SPT procedure. The Cone Penetration Test is becoming significantly popular in-situ test to investigate a site and to do geotechnical design. It is useful in-situ test to delineate stratigraphy and to continuously measure parameters such as qc and fs. The merits of CPT method as the soil investigation tool are the repeatability, continuous record and simplicity.

A large amount of data has been built based on the SPT so that it is needed to use the data with the introduction of the CPT method. First chapter is a short introduction about SPT and CPT methods. Chapter 2 shows how the SPT was made and how the energy is travelled in the rod when the hammer hit it. In addition, what kinds of factors affect the N-value, how other parameters are related to the N-value and how SPT is applied are shown. Chapter 3 introduces the four cone penetration tests types, how CPT is applied and what kinds of parameters can be estimated from the CPT. In Chapter 4 I have illustrated some examples where the correlation between SPT and CPT was studied. In these various soils the correlation between qc/N and D50 is useful, but in other cases it may be not reliable. Therefore, more samples are needed to sharpen the reliability of the correlation between qc/N and D50 and other studies are recommended to improve the reliability of the correlation between qc/N and D50.