Construction Of Soil Database Of Physical And Mechanical Parameters And Analysis Of Its Correlation And Probability Statistics

Large number of experimental data and observation data are obtained in the procedure of studying problems in Geotechnical Engineering and constructions, these data are very useful for later construction and design, but it was hard to do large scale of statistic and analyses for the lack of suitable tool. The program of database provides a wonderful method to collect these data and then study on them. Study on these geotechnical data with mathematical and statistic method has very important referential use for traditional design method and reliability design.After collected nearly 120000 data from engineering investigation reports of 17 projects, soil database system is worked out with SQL and the language of VB. With this system, save, inquire and manage character can be conveniently reached. For the users who login database system, different limits of authority are given by different user identities.Based on the database, this paper put emphasis on geotechnical parameter of eastern China, and such analysis and studying are done:Firstly, the correlation between geotechnical parameter is studied. Unitary linear regression is done between w~e, w~ρ, e~ρ,w_L~w_P. For α_v , C_ c between w, ρ , e, w_P in eastern China, unitary linear regression is done to silty clay as well as multivariant regression with coefficient iteration method and least-squares procedure are done to all kinds of soil, and the two results are compared. Unitary linear regression and multivariant regression are done to c_q, φ, c_d, φ_d between e and I_P. Unitary linear regression and multivariant linear regression are done to napierian logarithm of q_u between e , I_L, w_P and w_L, then the equations of regression are checked with other parameters.Secondly, the geotechnical data of 8 projects in eastern China are reclassified to ML , CL, MH and CH according to W_L and I_P. Then coefficients of variability of physical and mechanical parameter are given.Finally, the physical index and compression index of silty soil from Yangtze Basf project are divided to three groups according to depth, then characteristic statistic are calculated to physical and compression index of three groups and mechanical index of all depths. After that, normal distribution , logarithmic normal distribution and extreme I distribution are fitted for physical and mechanical indexes. And Goodness-of-fit testing with X~2 method is done subsequently. After probability density functions are obtained, the procedure and result of parameter optimization using Bayes method are represented with estimated value of pressing factor.The author expects the work done in the paper can play a positive role in richening district data and researching the reliability in geotechnical engineering.