The Engineering Properties Research Of Hard Shell Layer Soft Soil Foundation

Soft foundation surface because of water evaporation,groundwater level lower,load transfer,soluble salts and other components deposit and other factors of long-term effect,would form a layer of hard shell layer,the characteristics of its bearer will be quite different from the concept of people often knew. at the present stage,at home and abroad there are little research at the foundation of hard shell layer,in practical engineering calculations it is basically use of the similar theory to solve,it makes that some of the results are not accurate.In this paper,on the basis of summed up the study status quo and progress at home and abroad,analysis and research mainly carried out from the following some aspects :1.It analyses the main causes of hard shell layer formed and the special role and its effect of project;2.By using two-parameter model it analyses hard shell layer soft soil foundation stress,obtaining the stress diffusion coefficient calculation method about interface of hard shell layer soft soil foundation at the condition of strip and uniform load,and by means of project examples to illustrate that the calculation method is feasible.3.It analyses pro plastic load of homogeneous foundation and hard shell layer soft soil foundation at the condition of strip and uniform load, improves impact and shear damage theory formula proposed by Meyerhof and Hanna at the condition of considering multi-role of hard shell layer,and by means of project examples to verify the formula deduced.4. The use of numerical simulation methods, by changing the various mechanical parameters, study the effect about the level of stress.Through this paper,in the calculations of layered foundation settlement and ultimate bearing capacity,by uesing of the stress diffusion coefficient method and considering the role of a variety of hard shell layer,the results are closer to the actual value of the project. It makes that the reliability and economy of the project is more fully.Because of the specificity of engineering properties,both at home and abroad the study about engineering properties of hard shell layer soft soil foundation is little,in particular,field test data is very few. In the course of future research it is necessary to carry out many field test in order to verify the theory. In the process of application and study in the future,the knowledge need to be enriched and sumed up about hard shell layer,and reach maturity and perfection,so that it can be given full consideration in design and construction for the future.