Influence of water and rock particle contents on the shear behaviour of a SRM

The contents of both water and rock particles are important factors affecting the mechanical strength of a soil–rock mixture (SRM) filled subgrade in the western mountainous area of China. Therefore, the purpose of this paper is to study the mechanisms of reconstituted landslide deposit samples with different water and rock particle contents by analysing the characteristics of shear strength, volumetric strain and ‘jumping’ phenomenon via large-scale direct shear tests. The results show that the influence of water content on shear strength is greater than the influence of rock particle content under a lower normal stress, and the results are reversed in the case of a higher normal stress. The effect of water content on the equivalent cohesion is bigger, especially for the sample with a high rock particle content. The friction angle of the specimen with same water content increases with the increasing rock particle content, but when the number of rock particles increases to a certain extent, there is a little effect on the friction angle. However, the friction angle decreases with increasing water content at the same rock particle content. Specimens with the same rock particle content change from dilation to compression with increasing water content. Finally, the continuous stage of the ‘intense jumping’ at different water content has been analysed. The ‘jumping’ phenomenon of samples with low water and rock particle content will first strengthen and then weaken the samples with increasing normal stress.