Research And Study On The Coefficient Of Subgrade Reaction Testing Method

This paper relied on coefficient of subgrade reaction test of foundation soil which is the subway line 2section E in Xi'an during geotechnical engineering reconnaissance. According to the geotechnical engineering condition of the research area foundation soil, and request of national related criterion was combined, a few adaptive testing methods were chosen to experiment, research and apply, then the coefficient of subgrade reaction suggested value was confirmed comprehensively, also, some suggestions to coefficient of subgrade reaction testing work were given.At first, according to the geotechnical engineering condition of the foundation soil in research area, namely typical foundation soil of loess region, and the national criterion—《geotechnical engineering reconnaissance criteria of subway and light rail transit》(GB 50307-1999)was combined, this paper put forward two testing methods of coefficient of subgrade reaction: K30 load test and laboratory triaxial test or consolidation test. In consideration of synchronously with drilling, specification for cone penetration test, pumping test and so on, K30 load experiment ( pump experiment is used to precipitation when layer is underground water level ),laboratory triaxial test (during drilling)and flat dilatometer test (together with Specification for cone penetration test) were chosen as four testing methods of testing coefficient of Subgrade Reaction in research area.After that, this paper introduced these four methods of testing coefficient of subgrade reaction respectively which adopted by research area, mainly introduced various theories basis, experiment principle, equipments, important points, data settled and results application of every test method, at the same time, the requests of every experiment and operating steps of experiment were introduced simply.Thirdly, the equipment, experiment processing and contents of four testing methods mentioned were introduced in detail, and detailed original data were settled and analyzed detailedly based on data and results from four tests. Then the coefficient of subgrade reaction k was given according to foundation soil (namely depth). Among them, the Vertical coefficient of subgrade reaction Kv and horizontal coefficient of subgrade reaction kx of foundation soil educed from K30 load experiment and laboratory triaxial test, the horizontal coefficient of subgrade reaction kx of foundation soil educed from pressurementer test and flat dilatometer test.At last, the results of four kinds of testing methods were simply contrasted, analyzed and discussed to research area, also, the coefficient of subgrade reaction experienced value was consulted and opinion of experts syndic was combined, with principle of" on the safe side and reasonable economy ", the coefficient of subgrade reaction suggested value of each foundation soil layer was confirmed synthetically. At the same time, the own suggestions of coefficient of subgrade reaction testing method were given and original data was provided for accumulating coefficient of subgrade reaction experienced value.