5/24/2023 0 Comments Crack radiant defense![]() ![]() Under the same test conditions, indoor uniaxial compression creep AE tests were performed on intact and artificially fissured sandstone specimens using a rock rheometer and a PCI-Ⅱ AE tester controlled with an RLJW-2000 microcomputer. This study investigates the effect of prefabricated fissures on the creep mechanical strength and acoustic emission (AE) characteristics of sandstone. However, with increasing long preexisting fissure length, the short preexisting fissure was subject to crack propagation and coalescence. The preexisting fissure angle and two preexisting fissure distances had a negligible effect on the UCS values of the rock-like materials. In contrast, increasing the long preexisting fissure length influenced the crack propagation and coalescence more extensively in the case of a long preexisting fissure. A large preexisting fissure length significantly influenced the peak strength and coalescence, and the uniaxial compressive strength (UCS) values of the rock-like materials decreased. Uniaxial compression tests of specimens with preexisting fissures of two unequal lengths were conducted, and the influence of preexisting fissure angle, the distance between the two fissures and fissure length on the peak strength and coalescence mode of specimens were analyzed. Three different types of specimens with preexisting fissures can be broadly categorized: specimens with few preexisting fissures, specimens with multiple preexisting fissures, and specimens with preexisting fissures and other flaws. The development of specimens with different preexisting fissure types was examined in this study. Strengths were both increased as the filling dimensions increased (for the case of a bridge area with a particular fixed length).įissures substantially impact the engineering stability of rock masses, making research on rock masses with preexisting fissures essential for engineering activities. The shear cracks mainly initiated from the crack (joint) tips and coalesced with another one. It has been shown that both tensile and shear cracks may occur in the fillings. The loading was continued till shearįailure occur in the modeled concrete specimens. Was gradually applied to the model under a constant loading condition of 3 MPa (σc/3). Therefore, totally, 9 different types of samples were designed for the shear tests in PFC2D. The parallel bond model was used to calibrate and re-produce these Mm×5 mm were provided for different modeled samples. Three filling sizes with dimensions of 5 mm×5 mm, 10 mm×5 mm, and 15 Rectangular hollow was filled with cement material. Type narrow bands were removed from the central part of the model and different lengths of bridge areas (i.e., the distanceīetween internal tips of two joints) with lengths of 30 mm, 50 mm, and 70 mm were produced. The dimensions of prepared and modeled samples were 100 mm×100 mm. The laboratory-measured properties were used to calibrate some PFC2D micro-properties for In this paper, the shear behavior of soft filling in rectangular-hollow concrete specimens was simulated using the 2D
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