Experimental Study On Nonlinear Rheological Model Of Soft Soil In Shantou

Blow fill soft soil is widely distributed in coastal areas of China.The special physical and mechanical properties of soft soil make it have obvious rheological properties.Therefore,engineering diseases are easy to occur when soft soil is blown in as foundation.In order to study the rheological mechanism of soft soil,the basic geotechnical test and a series of rheological tests were carried out on the original soil samples of the eastern urban economic belt of shantou city with water content of 28.80%?70.85%and plasticity index of 14.90?40.00,and the following results were obtained:(1)The physical and mechanical properties of shantou undisturbed soft soil are analyzed.The relationship between basic physical indexes such as water content,pore ratio and density and other physical indexes is analyzed.The mechanical properties are described by Duncan-Chang model The results show that there is a good linear correlation among all the physical indexes except the plasticity index.Within the range of soil samples selected in this paper,the parameters of duncan-zhang model K?n?c???kb and m all vary greatly Rf value fluctuates between 0.54 and 0.89(2)Based on one dimensional rheological test in laboratory,the factors affecting the secondary consolidation characteristics of soft soil were analyzed by”Chen's loading method The results show that the load grade and overload ratio have good exponential relationship with the secondary consolidation coefficient,and the recompression load has good exponential relationship with the secondary consolidation coefficient.When the water content and plasticity index are low,the secondary consolidation coefficient is small.When water content and plasticity index increase,the secondary consolidation coefficient increases correspondingly(3)Based on laboratory test data,Singh-Mitchell empirical model related to water content and Logistic empirical model with four parameters k?j?m?n were established respectively.Based on the original Burgers model and the effective stress principle of saturated soil,a modified Burgers model for soft soil was proposed(4)In combination with practical engineering,the three rheological models fitted are compared with the settlement calculation rules obtained by the conventional layering summation method.The results showed that the settlement errors of Singh-Mitchell model,Logistic model,modified Burgers model were 0.5%,0.3%and 0.1%to conventional hierarchical summation method at 50 years.