The Analysis On Gravity Stress,Settlement And Geotechnical Parameters Spatial Variability Of Lacustrine Sedimentary Soft Soil

There are many influence factors about the calculation of gravity stress and final settlement of soft soil.And the analysis of soil shear strength parameters is complicated.In order to better understand that how the sedimentation affects the gravity stress and settlement of soft soil and to study the spatial variability of subsoil's shear strength parameters.The paper studied the computing method of gravity stress,settlement and the spatial variability of shear strength parameters based on the Advanced Soil Mechanics and Geostatistics.Main research content in dissertation includes the followings:(1)The paper have collected a lot of laboratory soil test data of Dianchi Lake international conference and exhibition Center foundation soil.And the relationship between the shear strength paraters of peat soil,clay and floury soil and the influence factors is studied.The relationship between the shear strength of peat soil and its organic matter content was studied emphatically.It was found that there was a certain correlation between the shear strength parameters of these three soils and their average number of penetraion and natural water-content.With the organic matter content increasing,the specific gravity of peat soil is decreasing.(2)Soil sedimentation and stress history have great impact on the determination of soil gravity stress and the final settlement of the foundation soil.Due to the accurate and convenient of e-lnpcoordinate in dealing with the linear problem over e-lgp coordinate,thus e?ln p is often applied to calculate the influence of sedimentation and gravity stress of the normal consolidated soil and over-consolidated soil.This formula is to used to calculate the gravity stress value and final settlement value of deep soft clay which came from Kunming exhibition Center near Dianchi Lake,while the calculation result is used to make a comparison with historical data of stress value and settlement impact,the result shows that the sedimentation has great impact to the gravity and final settlement value of deep soft clay,furthermore,the more thicker of the soil will bring the bigger of the overlying load consistently.(3)In the study of the spatial variabilities of the shear strength parameters of the foundation soil,due to the large differences in the shear strength parameters of the soils at different locations and burial depths in the same study area.In order to solve this problem,the genetic algorithm is applied to fit the peat soil and clay shear strength parameters of Dianchi Lake international conference and exhibition Center foundation soils of spherical model variation function,because the genetic algorithm have the advantage on seeking priorities in fully exert when use it to solves the non-linear problems.Furthermore the spatial variabilities of the peat soil and the clay is researched.By analyzing the datas of the research,It was found that the variation range of shear strength parameters of peat clay and clay in the east and west direction and in the north-south direction are larger than thouse in the vertical direction.And the variation range of cohesion of this two soils in the vertical direction is less than the variation range of the internal friction angle.(4)The estimation of Kriging is a valuation method which takes the spatial variation duality into consideration.But for many years,there is a problem that the nonnegative constrains are not taken into consideration in the weights of estimation.This problem impacted on the estimation of actual results.The entropy weight theory models calculating the weights of estimation in which the nonnegative constrains are taken into consideration are proposed to overcome the malpractices existed in the related Kriging equations.Both the correction of coefficient of weight and the correction of sample point of distance are taken into consideration in improving the negative weight.And the paper calculated the shear strength parameters of the peat soil and the clay of Dianchi Lake international conference and exhibiton Center foundational soils by using 2 kinds of methods that improved before and after.By comparing these two results of valuation of the peat soil and the clay.It is found that the valuation which is calculated by improved estimation of Kriging is more accurater than the valuation which is calculated by non-improved estimation of Kriging.The results of the paper can improve the accuracy of the final settlement calculation of soft soil foundation.And it could improve the efficiency of geotechnical engineering investigation but also reducing the investigation cost by analyzing the law of the spatial variability of the shear strength parameters of the soil,...