The Study On Strength Characteristic And Cutting Slope's Stability Of High-liquid Limit Soil

There is a wide range of granite weathering residual soil distributed in Guangdong Province.Compared with other high-liquid limit soil,influenced by parent rock it has special engineering characteristics besides the common traits of high natural water content,high saturation,high liquid limit,porosity,high compressibility,low permeability and hard to compact..The high-liquid limit granite weathering residual soil along Guangwu Expressway was taken to study the physical-mechanical characteristics from different angle with laboratory tests and microcosmic-test.The most important difference between high-liquid limit granite weathering residual soil and other high-liquid limit clay or silt is the large content of coarse particle.It is a kind of mixed particle soil so that high-liquid limit granite weathering residual soil has its own specificities.It has loose microstructures,weak expansibility,bad cohesiveness,and no obvious strength softening.It is easy to loose when wet and cohesion reduces quickly.This is the main reason of strength decaying after wet,for internal friction angle is influenced less evidently.Besides,laboratory repeat-shear test can not determine the residual strength of this kind of soil well.So reliability of the results is not satisfactory.There is improvement to be expected.General stability analyses and centrifugal test were taken with the model of Guangwu Expressway cutting slopes and the data of laboratory tests.The traits of failure in high-liquid limit granite weathering residual soil cutting slope is not only general instability but also collapse,landslide and face impact erosion,slip in surface layer.So when excavating, reinforcement must follow closely and drainage and slope protection must be taken in time.