Model Test Study Of Recently Reclaimed Soil

In the development and construction of Tianjin Binhai New Area, the vacuum preloading method is widely used in land reclamation. As a mature method, the reinforcement mechanism and the effects of vacuum preloading were fully studied and verified. Different from the past,the object of vacuum preloading is changed to recently reclaimed soil.The thickness of foundation is changed from 2m to the current 10m,the recently reclaimed soil have many characters like low-intensity, high water content, there are many problems due to these characters in vacuum preloading method and the reinforcement effect. In order to solve these problems the paper did some studies on the reinforcement mechanism and test as followings:The indoor model test study was conducted to the recently reclaimed soil.The water content of the reclaimed soil is 80% and it is super-soft soil. With the development of land of Reclamation, the bottom elevation of the reclaimed area getting lower and lower, the thickness of the reclaimed soil reached 10m from the original thickness of 2m now, so that a great deformation occured in the course of the vacuum preloading. There are some phenomena that hard to explain. In order to solve these problems, this paper carried out an indoor model test. Some research have been done through the experiments: (1)Though the indoor model experiment it was found that the PVDs has undergone a drastic distortion and even part of it was breaken due to large deformation of the soil during the vacuum preloading, this result the efficiency of the PVDs reduced, so that the soil reinforcement is ineffective and can not achieve the desired bearing capacity of foundation requirements. (2) in order to make secondary reinforcement, secondary PVDs installation was carried out, results show that the settlement was further developed,water content was further reduce,vane strength was further improved, and the Vane strength decline rate greatly developed. the distribution of vacuum degree along the PVDs and in the soil was also be studied. The test result provide reference to explore a more effective method of reinforcing the deep reclaimed soil foundation.At the same time,this paper use ABAQUS FE soft to simulate the entire process of the modle test,assuming that there is no distortion to the PVDs.The results show that reinforcement was better than the modle testl, further confirming the distortion of the PVDs reduceed the reinforcement effect.In order to make a quantitative analysis of the effect to the vertical discharge capacity from bending deformation of the PVDs,this paper made a comparison of the vertical discharge capacity test from the bending PVD and the normal one,using the latex film water mete .The test result provide that the efficiency of the PVDs reduced.