Experimental Study On Plane Strain Mechanical Properties Of Soil-Rock Mixture

As a kind of common geological body,soil-rock mixture is widely existed.Its macroscopic physical and mechanical properties and deformation and failure characteristics not only depend on the physical and mechanical properties of "soil",but also depend on the content,spatial distribution,morphology,particle size composition and other meso-structural characteristics of"block stone" to a large extent.Most of the existing tests on the mechanical properties of soilrock mixtures focus on large direct shear tests or large triaxial tests,but do not consider the mechanical properties of soil-rock mixtures under plane strain conditions.Aiming at plane strain engineering,which is common for soil-rock mixture and m aterial,this paper conducts consolidation drainage shear test and lateral unloading test for soil-rock mixture under plane strain condition considering different stone content and consolidation confining pressure by using the modified rigid and flexible mixture type large true triaxial instrument.Based on the experimental data,the mechanical properties of soil-rock mixture under plane strain condition are analyzed and studied,which provides an important basis for further improving the plane strain engineering of soil-rock mixture and its mechanical research.The main research achievements of this paper are as follows:(1)In the consolidation drainage shear test under plane strain condition,the strength of the soil-rock mixture increases with the increase of the stone content or consolidation confining pressure,and the change law of the principal stress and middle principal stress coefficient and the lateral deformation and bulk strain of the soil-rock mixture under the influence of the stone content and consolidation confining pressure is obtained.(2)In lateral unloading test under plane strain condition,the stress-strain relationship of soilrock mixture un der different rock content and consolidation confining pressure condition is analyzed,and the law of medium principal stress and medium principal stress coefficient change with the reduction of lateral load is obtained,and the influence of different test conditions on lateral strain and bulk strain is also obtained.(3)Mohr circle and strength envelope of soil-stone mixture were drawn based on the data obtained from consolidation and drainage shear test.It was obtained that the cohesion increased linearly with the increase of stone content.Although the internal friction Angle also increased with the increase of stone content,the range of change decreased when the stone content was greater than 50%.(4)Derived on the basis of the cohesive soil of principal stress and the strength criterion formula,the formula of the validated for the data from experiment,the results show that the overall high principal stress measured values compared with the calculated value of LadeDuncan strength criterion,and on p-q curve(?)sigma space strength criterion of the sliding surface is calculated with the measured values agree with high degree of trials.(5)According to the lateral stress-strain curve obtained under the condition of plane strain lateral unloading test of soil-rock mixture,the variation rule of the parameters of the nonlinear composite power function model under the influence of the internal stone content of soil-rock mixture was analyzed,and the applicability of the model was verified.