Abstract
A conventional triaxial compression test of Jurassic‐Cretaceous typical weakly consolidated sandstone from a mining area in Ordos, China, was conducted using an MTS816 tester. Results showed that, before the peak, the rock had a distinct yield stage. When the specimen reached its peak strength, the strength decreased rapidly and showed an obvious brittle failure. When the confining pressure was increased to 15 MPa, the decrease of strength was slow and the rock tended toward ductile failure. With the increase of confining pressure, the cyclic strain initially increased slightly, whereas the volumetric strain increased greatly and the rock sample was in a compression state. When the load reached a critical value, the curve was reversely bent, resulting in volume expansion, whereas the peak strength, residual strength, and elastic modulus increased with confining pressure, and Poisson’s ratio decreased with the confining pressure. In the model based on macroscopic failure rock, the expression of the relationship between fracture angle and confining pressure provided a solid theoretical basis for the direction and failure mode of the macroscopic crack. Based on the rock strength theory and Weibull random distribution assumption of rock element strength, the damage variable correction coefficient was introduced when the residual strength was considered. Then, the mathematical expression of the 3D damage statistical constitutive model was established. Finally, the theoretical curve of the established constitutive model was compared with the triaxial test curve, which showed a high degree of coincidence.
Highlights
A conventional triaxial compression test of Jurassic-Cretaceous typical weakly consolidated sandstone from a mining area in Ordos, China, was conducted using an MTS816 tester
By integrating 3D laser scanning with geographic information system technique in their analysis, Song et al [5, 6] found that the reduction of shear strength was correlated with the cohesiveness of skeleton particles and the softening characteristic of cementing material after absorbing water was a key deciding factor in Advances in Civil Engineering the fracture appearance induced by shear failure. rough field research, theoretical analysis, and laboratory test, Sun et al [7] compared rocks in an eastern mining area and weakly cemented rocks in a western mining area and obtained burial depth-dependent change features of elasticity modulus, compressive strength, tensile strength, cohesion, internal friction angle, and Poisson’s ratio of the rocks
Rough a uniaxial compression test of weakly cemented argillaceous sandstones under natural and dry states, Li et al [8] observed that the mechanical properties of dry rock samples were approximately identical to those of hard brittle rock; for moisture-containing rock samples, elasticity modulus and postpeak residual stress deteriorated to different degrees, but lateral swelling deformation increased
Summary
As a result of these typical engineering mechanical properties, coring from the weakly cemented rocks becomes difficult; the coring rate is extremely low, and acquiring complex mechanical properties through the laboratory test is difficult [1, 2]. Various safety accidents, such as roof caving, collapse, and support failure, usually occur in soft rock roadways. Previous studies on weakly cemented rocks have achieved important results with emphasis on microstructural morphology, rock deformation behavior, and constitutive relation, but few studies have explored the failure characteristics of Cretaceous-Jurassic sandstone under triaxial compression conditions and the constitutive relation considering the correction of residual strength.
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