Development of Miniature Cone Penetrometer and Study on MCPT in Silty Clay

A new kind of miniature cone penetrometer was developed in order to acquire automatically the cone penetration resistance and depth in MCPT. At the same time, a!new experimental facility was developed to make soil samples for MCPT. A series of penetration tests for silty soil were carried out with the miniature cone penetrometer. It is found that the penetration curve has no relation with the angle of cone and its initial segment is straight. For silty clay, cone penetration resistance will tend to be changeless when the penetration depth attains to a certain value. This is caused by the different failure mechanism of soil under different lateral compressive stresses. The relation between the characteristic values of penetration curve and soil mechanics parameters was analyzed. It is found that the dimensionless cone resistance factor is linear with tanφ where φ is the internal friction angle of soil. In addition, the experiential relation between limit cone penetration resistance and critical depth is obtained.