Research On Mechanical Properties Before And After Surface Grouting Rock Structures

The stability of rock mass engineering is mainly controlled by structural plane. The current study of structural plane concentrate on three types including straight, undulant and serrate, but the research on mechanical property and grouting effect of step_shaped structural plane is less. Based on theoretical analysis, sample test and numerical simulation, the mechanical properties of three types including one step_shaped, two step_shaped and one step_shaped with one serrate structural plane are investigated pre-and-post grouting. The main content and conclusions are as follows:(1) On the basis of the mechanical model established by previous researcher, The shearing stress, cohesion and friction expression of serrate structural plane in climbing or shearing failure are derived. The expressions of step_shaped structural plane in crush-cutting failure are also derived.(2) The essence of grouting reinforcement of structural plane is revealed through the shearing test, that is the change of cohesion and friction.(3) According to the results of sample test, fracture aperture’s shear constitutive model and shear-swelling model are established, which coinciding with test results.(4) Based on sample test and numeral simulation, the shear destruction characteristic of structural plane are analyzed which aspect ratio are0.5and0.3.(5) Normal stress and shear strength is similar to linear relation and shear strength increases with normal stress via the results of test.(6) The sample test show that shearing strength is improved above20%on average by grouting. The shearing strength increased markedly after grouting from the results of sample test and numerical simulation.(7) A modified Mohr-Coulomb formula which introduce the non-controlling climbing angle factor ki is established.