EFFECT OF STRONG STRUCTURE ON RCPTU TEST RESULTS FOR MARINE CLAYS DEPOSITED IN NINGBO CITY, CHINA

摘要

The structure of soft soil has major effects on its properties, and this structure varies from place to place. This study investigates the effect of structure on resistivity piezocone penetration (RCPTU) test results for soft marine clay in the Ningbo area, China through analysis of the values obtained for soil parameters such as electrical resistivity, sensitivity, undrained shear strength and coefficient of consolidation. The results show that the penetration index is high at Ningbo, namely,q_c=(1.0?3.0) MPa, and the average value of the friction ratio, R_f is about 0.85%; highly accurate soil classification can be achieved by RCPTU testing for this strong-structured soft marine clay; the electrical resistivity of soft clay is a good reflection of its properties and microstructure; in strongly structured soil, the deeper the soil is beneath the surface, the shorter the CPTU pore pressure dissipation time becomes and the larger the consolidation coefficient of the soil becomes and the larger the consolidation coefficient of the soil becomes; shear dilatancy occurs at the initial stage of pore pressure dissipation; damage done to the soil structure by the process of penetration causes the permeability of the soil around the probe to decrease rapidly and index distortion to occur. These research results provide a reference for the design of foundation treatments for structured soft soil and have important significance for engineering applications.