Soft Soil Bearing Capacity Parameters With The Foundation Treatment Plan Optimization

Strengthening research on the subgrade of soft soil and scientificallychoosing the processing scheme of the soft foundation soil has greatimportant significance in quality of express highway construction. Basedon the soft soil treatment project in Xiangtan-Shaoyan Express Highway,a section of Shanhai-Ruili Express Highway, the author has in detailstudied the in-situ testing methods of soft foundation, the correlation ofthe parameters of bearing capacity of soft soil and the optimizationmethods of subgrade treatment. The main conclusions are as follow.Firstly, the field prospecting, in-situ testing and lab experiment oftwo sites in Xiangtan-Shaoyan Express Highway has been done. And,basing on the data from the field and lab test, the correlation ofparameters of bearing capacity of soft soil has been studied. It shows thatthe correlation relationship of the soft soil is good or excellent, includingthe correlation between water content and modulus of compressibility, orvoid ratio, or relative water content, the correlation between lightsounding test blow dynamic point resistance and cohesion, or modulus ofcompressibility and relative water content and void ratio. The followingcorrelation is better or general, which mainly includes the correlationbetween cohesion and water content, or relative water content, or lightsounding test blow counts, correlation between void ratio and modulus ofcompressibility or coefficient of consolidation, and correlation betweencoefficient of consolidation and plasticity index. But, the correlationbetween cohesion and void ratio or vane strength is bad. The correlativeequations between the bearing capacity parameters have been established,and the comparison with other researcher conclusions has also been done.The conclusions in this study can be referred to other similar soft soilfoundation in determining the beating capacity.Secondly, the author has studied the various factors influencing thebearing capacity of soft soil by means of grey relational analysis. Someconclusions have been gained. Light sounding test blow count is the most sensitive to the bearing pressure by which we can utilize to examine thebearing value of soft soil in construction simply and correctly. Thesecondary sensitive influencing factors are field density, modulus ofcompressibility, cohesion and plasticity index. Those parameters can beused to calculate the bearing capacity in lab. Moisture content, void ratioand relative water content are of poorer sensitive to the bearing pressurerelatively.Thirdly, the scheme fuzziness in engineering design has beenanalyzed by applying fuzzy mathematics. And, the optimized project ofthe soft foundation treatment in Xiangtan-Shaoyan Express Highway hasbeen gained according to the theory of fuzzy mathematics.