The Study Of Cone Penetration Testing Methods And The Application In Offshore Engineering

With the rapid development of our social economy, we accelerate the exploration and utilization of marine resources, and the construction of offshore engineering has become more and more important. Depending on its own superiority, CPT has been more and more widely adopted and plays an important role in the offshore geological survey. However, the development of marine has been paid less attention for a long-term in our country, so there is a blank in the development and adoption of offshore CPT, most of which are imported from abroad. China has imported many CPT equipments, as well as the foreign procedures and interpretations of CPT. Most of the interpretations are particularly for experience formula of seas application, but whether it is applicable to our seas or not remains to be further studied. By contrastive analysis of testing mechanism, acquisition of the empirical formula with the other methods, this paper will explore the research of the CPT equipment applied in our country.First of all, the development and the testing methods of CPT will be briefly described. The CPT is composed of penetration system and the cone. According to different processes of penetration, the means of CPT can also be divided into two parts, that is, Seabed CPT and Down-hole CPT. In this paper, advantages and disadvantages of these two kinds of CPT will be discussed.Secondly, this thesis will make an analysis of the Test Mechanism of CPT from the aspects of theory interpretation as well as Finite Element Simulation. In theory interpretation, first of all, the cone penetration of CPT and the changes of the status of the soil around the cone will be studied, and then the theoretical calculation of the initial pore pressure distribution will also be discussed. Finally, cavity expansion theory and strain path theory and Hydraulic fracturing theory will be introduced. In Finite Element Simulation, ABAQUS software will be adopted, which can help to have a clear simulation analysis of penetration process, and also can promote to have a comprehensive analysis of the changes of soil displacement field during the cone probe process, and ultimately revealing the Test Mechanism of CPT. Focusing on the applicability of CPT to our seas, the classification of soil type and empirical formula of solving soil parameters will also be discussed in this paper.Finally, based on the two kinds of measured data of CPT in our seas and by contrastive analysis of inside test results and on site test results, the processing methods of CPT number, the applicability of empirical formula and the range of empirical parameters will all discussed.