Study On The Humidity Field Distribution Law And Stability Of Chengdu Unsaturated Clay Foundation Pits Under Rainfall

With the development of urban agglomerations in southwest China,the scale of urban construction has gradually increased,and result in a large number of new geotechnical problems.In the process of project construction,natural disasters frequently occur in unsaturated expansive soil areas,and engineering problems are encountered one after another,especially the problem of foundation pit engineering under rainfall conditions.In Sichuan,the “ Chengdu Clay ” with a wide distribution area is a typical unsaturated expansive soil.Many foundation pit projects in the distribution area of "Chengdu Clay" according to statistics may be damaged due to rain and other water-related factors if proper steps aren’t taken.This article focuses on the study of the distribution and stability of the humidity field of foundation pits of "Chengdu Clay" under rainfall conditions.This thesis summarizes and analyzes the basic characteristics of "Chengdu Clay",and obtains its main characteristics.Combining with unsaturated soil theory,it makes a certain exploration on the moisture field distribution law and stability analysis of foundation pits.First,in order to obtain the soil-water characteristics of "Chengdu Clay",the original sample taken on site was tested by the GCTS soil-water characteristic pressure plate instrument.And the VG simulation is used to fit the soil-water characteristic curve of "Chengdu Clay",and the applicability of the fitting equation is verified by the evaporation test.Subsequently,on the basis of the experiment,the internal factors(the fissures of the "Chengdu Clay")and external factors(different rainfall conditions)that affect the distribution of the moisture field of the foundation pit of the "Chengdu Clay" were considered respectively to consider the moisture field of the foundation pit under different conditions.Provide some references for the reasonable anti-seepage and drainage design and construction of foundation pits in this area under rainfall conditions.Finally,the influence of soil swelling force and strength attenuation is considered in the calculation model,and the stability and reliability of the foundation pit are analyzed according to the actual situation.The results show that the basic characteristics of "Chengdu Clay" should be fully considered in the design and construction of foundation pit engineering in the distribution area of "Chengdu Clay" and targeted design and construction should be carried out,otherwise it will bring certain hidden engineering hazards.