Research On Strength Test And Strength Increasing Calculation Theory Of Soft Soil Foundation

Stability and deformation are two major problems in constructing buildings on soft ground. And Soft soil strength is a decisive factor in stabilizing soft ground. Soft soil strength increasing with the drainage consolidation is one of the important engineering characteristics. It is very important for soft ground of the low bearing capacity to increasing strength. To Master growing rule of strength is the foundation of reasonable controlling embankment filling velocity on soft soil, shortening the construction period and getting more scientific and more economical embankment filling method. Combined with communications science and technology project in Hunan and basis of researches at home and abroad, a number of exploration on the growth mechanism of soft ground strength, calculation method and engineering applications have been carried out relying on in-situ test of soft ground of expressway in Hunan, indoor and outdoor tests on soft soil strength parameters and theoretical analysis. The research results are as follows:(1) Systematically carried out three kinds of in-situ test on strength of soft soil foundation between mountains in Hunan. Regression equation of the cross plate shear strength (Cu) and light sounding test blow count (N10) was established. Those test research fruit laid the foundation for soft soil strength analysis of in-situ tests in test area.(2) Large amounts of physical and mechanics parameters test were carried out. Regression equation of parameters individuals and laboratory test index and in-sute test index based on test data. Factors influencing the bearing capacity of soft soil foundation is studied by means of grey relational analysis. Test fruit can heip to master the engineering characteristic of soft soil between mountains.(3) The consolidation tests and direct shear tests of soft soil were performed. The law of shear strength index of soft soil change with its degree of consolidation under different consolidation was studied. The affection of loading method, namely, one time loading and the stepped loading on thelaw of shear strengthwas researched. The relationships between degree consolidation and index of shear strength were recommended. The result can be referenced to the fill construction of embankment on soft soil.(4) Fully considering bearing capacity characteristics of the basement (flexible foundation, trapezoidal load distribution and strength increase due to consolidation), through theoretical derivation, calculation theoretical formulas of bearing capacity of low fill soft soil foundation was achieved. A new method was presented for assessing the bearing capacity under embankment at construction stage.(5)The formula is applied to calculate the increments of bearing capacity of soft soil foundation.Baesd on calculation results,a bearing capacity increasing calculation table was put forwads,which enhance the application value of the formula.(6) Considering soft soil foundation strength increasing with time (consolidation) and combining the stability analysis with settlement calculation organically to overcome the previous shortcomings; based on growth theory of strength, the research propose a dynamic control computing method of construction of embankment considering the stability and post-construction settlement and prepare the computer application program as well.