Experimental Study On Treatment Of Soft Foundation With Combinational-ordered Drainage Consolidation Method

With the acceleration of urbanization,construction land supply has been in shortage in recent years.Therefore land reclamation from the sea becomes a practical method to expand the urban space.Such filling land can't be used as construction land until it has been improved by some foundation treatment technique.This paper introduces all kinds of treatment methods for large area of soft foundation,and analyses their basic principles and application.Based on that,the paper innovates the combinational-ordered drainage consolidation method and describes its principle.An experiment has been designed to prove the method's effectiveness and advantages with an actual project case in Caofeidian.Building the proper transfer layer is the key to establishing the combinationalordered drainage system and it allows the separate drainage system for upper and lower layer according to their properties,thus increasing the reinforce depth greatly.The paper has demonstrated such following conclusions thorough contrast test of dynamic compaction combined with dewatering:(1)the combinational-ordered drainage method uses the dewatering system of vertical pipe combined with horizontal filter pipe to achieve the goal of unstoppable dewatering;(2)for the lower saturated clay,the combinational-ordered drainage consolidation method has increased the undrained shear strength twice than before while the contrast method can only double the undrained shear strength;(3)the combinational-ordered drainage consolidation method can finish the lower saturated clay's consolidation degree to 85% in three months,and it saves almost three months than the contrast method.This paper has proved the method's effectiveness and advantages on land reclamation from the sea through the contrast test and has summarized some fundamental design advice on the method' engineering application,thus the method is practically valuable.