单轴压缩条件下含水平单薄层膏盐泥岩力学特性试验研究OA

The gypsum-salt mudstone with thin layer is a typical"soft layer sandwiching hard layer"composite rock mass frequently encountered in hydroelectric and water conservancy projects at China's red-bed basins.It exhibits complex mechanical behavior in engineering construction.In this study,we conducted uniaxial compression tests by a custom-developed rock testing system capable of full-process monitoring and omnidirectional deformation-failure measurement,aiming to investigate its deformation-failure mechanisms and mechanical characteristics.The experimental results reveal that:the side shape of the sample is a'gourd'shape,and the characteristics become more obvious with the increase of water content(ω)of mudstone mass.When the sample is dried,the side shape of the sample is as the same as that of the pure mudstone.When ω increases,the difference of the lateral deformation between the two tests becomes greater.At the plastic limit water content,the maximum lateral deformations of the two tests are 2～2.4 mm and 1.6～1.8 mm,respectively.Thin gypsum salt rock has a hindering effect on the mechanical failure of the sample.The hindrance effect becomes more significant as the thickness of the thin-layer gypsum rock(D)increases.s When D is 1 mm,the thin layer is easily destroyed or even broken(ω<6%).When D is 4mm,the thin layer is not destroyed and the blocking effect is significant.The thin gypsum salt rock enhances the overall strength of the sample,and the maximum axial stress increases with the increase of D.Compared with pure mudstone,when D is 1 mm,the maximum axial stress value increases by 8.5%～11.9%;when D is 4 mm,it increases by 45.2%～50.3%.The research results can provide theoretical basis and experimental ideas for the experimental study of large deformation composite soft rock.