Abstract:The coefficient of consolidation and coefficient of permeability of the Lianyungang marine clay are studied by laboratory and piezocone penetration test(CPTU) in order to evaluate the consolidation and permeability characteristics. The horizontal coefficient of consolidation ch of the clay is also back analyzed according to field data of monitored settlement. Comparisons of the results obtained by different methods indicate that the values of horizontal consolidation coefficients determined by CPTU are in the range of (3.0–6.5)×10-3 cm2/s,typically 2–4 times higher than those of vertical consolidation coefficients. The value of horizontal consolidation coefficient with back analysis is slightly lower than that deduced from CPTU based on Teh and Houlsby¢s method. It could be possible due to the smear effect incurred during the installation of the vertical drains. For Lianyungang marine clay,it is recommended that Teh and Houlsby¢s method,which takes the rigidity index into consideration,should be used. The coefficient of permeability of Lianyungang marine clay is in the order of 10-6–10-8 cm/s. The value of horizontal permeability coefficient measured by falling-head permeability tests agrees well with that determined by CPTU. It can be indicated when the vertical drains are used in Lianyungang marine clay,the smear effect on consolidation properties of soil has to be taken into consideration in the soil improvement design. For soil improvement schemes of the Lianyungang marine clay,the coefficient of consolidation determined by CPTU dissipation tests is recommended in practice.