EXPLORATION ON DIVISION OF PRIMARY-SECONDARY CONSOLIDATION AND INFLUENTIAL FACTORS WITH SOFT SOIL

Division of primary-secondary consolidation is one of the key problems of prediction and analysis foundation deformation of soft soil correctly and taking effective engineering measures. A series of one dimensional compression secondary consolidation tests and three-dimensional secondary consolidation tests are performed by using unidirectional consolidation apparatus and triaxial shear apparatus for the typical soft soil in Tianjin. Load,pore ratio and pore water pressure,volume strain and time relationship are obtained. The test results show that: the division point of primary-secondary consolidation should be before the pore water pressure dissipation completely. A new method according to the strain rate and strain curve to differentiate the primary and secondary consolidation is founded. And the new method is suitable for all kinds of load. Primary consolidation time is prolonged along with increasing sample height while shortened along with the strengthening of drainage condition. With the increase of the load level,primary consolidation time is prolonged. When the load is less than the structure yield stress,thedivision of the primary-secondary consolidation is less affected by load ratio. While the load is greater than the structure yield stress,the primary consolidation time is prolonged along with the increase of load ratio. The ratio of the primary consolidation strain and the total strain after preloading is increased 30. 7% than that of no preloading.The ratio increases along with the increase of the preloading load.