Research On Effect Of Over-consolidation Ratio On Foundation Bearing Capacity Under Load

Faced with soft clay foundation,two methods are commonly used in engineering foundation reinforcement,which are named by stir in replacement method and drainage consolidation method.The former leads to different consolidation ratios of the lower part of the soil because of different thicknesses in stirring,the latter can result in different consolidation of soil due to the different amount of pore water discharge.While in the process of engineering construction,with the gradual construction of the rubble bed,caissons,fillers and other structures on the port,overlying load on the soft clay foundation gradually increase.Over-consolidation ratio,consolidation degree and the overlying load will have an impact on the soil shear strength index c,? value,but their impacts are often ignored in the engineering practice,which is not accurate and economical.Therefore,this paper carried out the research on foundation bearing capacity of over-consolidation ratio under load,the influence rule of over-consolidation ratio on soft soil shear strength parameters c,? value under load is obtained through the test,then put the rule into finite element software to calculate the bearing capacity of soil foundation,and then by calculating the safety coefficient of foundation bearing capacity to analyze the effect of different factors on the bearing capacity of the foundation.The specific work includes the following several aspects:(1)Use the indoor triaxial shear test,research the influence rule of the over-consolidation ratio and axial deviatoric stress on shear strength index c,? value of silt mass silty clay.The curve relationship was founded that the index c,? value increases with the increase of over-consolidation ratio,the greater the over-consolidation ratio increases,the slower the index c,? value of the soil samples increases;the linear relationship was founded that the index c,? value increases with the increase of the deviatoric stress.Finally uses formulas to fit the experimental data and put forward the formulaes of the variation of strength index c,? with over-consolidation ratio under load in the engineering practice.(2)Use the indoor triaxial shear test,research the influence rule of the consolidation degree and axial deviatoric stress on index c,? value of the silty clay and silt.It was founaed that c and ? increases linearly with the increases of the consolidation degree and axial deviatoric stress,Finally uses formulas to fit the experimental data and put forward the formulaes of the variation of strength index c,? with the consolidation degree under load in the engineering practice.(3)Put the index c,? value obtained from the fitting formula results into finite element software.By the form of numerical simulation,we can analyse the bearing characteristics of soft clay foundation bearing capacity.It was founded that the safety coefficient of foundation bearing capacity increases linearly with the increases of thicknesses in stirring.The curve relationship was founded that the safety coefficient of foundation bearing capacity increases with the increase of over-consolidation ratio,the greater the over-consolidation ratio increases,the slower the safety coefficient of foundation bearing capacity when the over-consolidation ratio is greater than 1,the load can make the safety coefficient of foundation bearing capacity increase by about 14%;When the over-consolidation ratio is 1,like the normal consolidation of soil,the load can make the safety coefficient of foundation bearing capacity increase by about 11%.The linear relationship was founded that the safety coefficient of foundation bearing capacity increases with the increase of the consolidation degree.