Science China Technological Sciences

, Volume 61, Issue 8, pp 1127–1136 | Cite as

Influence of water content and shear rate on the mechanical behavior of soil-rock mixtures

  • HouZhen Wei
  • WenJie XuEmail author
  • ChangFu Wei
  • QingShan Meng


Soil-rock mixtures (S-RMs) are widely distributed in the nature. The mesoscopic deformation and failure mechanisms as well as the macro-mechanical behaviors of the S-RMs depend largely upon the rate of deformation, water content and particle sizes. In this research, a series of large-scale direct shear tests with different water contents and different grain-size distributions were conducted to study the influence of the aforementioned factors on the mechanical properties of the S-RMs. Due to the effect of the rock blocks’ breakage in the S-RMs, the relationship between the shear strength and the vertical stress of S-RM follows a power law instead of a linear one. It is found that there exists a threshold value for the vertical stress during the shearing process, below which the soil strength is mainly determined by the inter-locking of particles and the re-arrangement of meso-structure, and otherwise large-sized rock blocks are gradually broken into smaller fragments, resulting in a decrease in the soil strength. The shear rate can also significantly influence the degree of particle breakage and the meso-structural rearrangement of the S-RMs, namely, under low shear rate, the particles of the samples are fully broken resulting in enhanced macro-strength. As a result, the lower the shear rate, the higher the macroscopic strength. So under unsaturated conditions, the water content will affect the strength of the S-RMs by reducing the strength of rock blocks. As the water content increases, the soil strength decreases gradually, and assumes a moderate value when the water content reaches 8%. At the same water content, the soil strength increases with the sizes of large rock blocks. For the occlusion, breakage and structure re-arrangement of the oversized rock blocks inside S-RM, which have a huge influence on the mechanical characteristics of the samples.


soil-rock mixture (S-RM) direct shear test water content shear rate particle breakage 


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Copyright information

© Science China Press and Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  • HouZhen Wei
    • 1
  • WenJie Xu
    • 2
    Email author
  • ChangFu Wei
    • 1
  • QingShan Meng
    • 1
  1. 1.State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhanChina
  2. 2.State Key Laboratory of Hydroscience and Hydraulic Engineering, Department of Hydraulic EngineeringTsinghua UniversityBeijingChina

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