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2 2024

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Numerical simulation of weathered granite considering microporosity and mechanical parameter variations

Zhao Kang, Liu Yang, Ma Chao, Yan Yajing, Feng Yincheng, Tian Xiangqing, Chen Tong

Archives of Civil and Mechanical Engineering

2024

Vol. 24, no. 2

art. no. e119, 2024

To study the deterioration of the mechanical properties of weathered granite and its damage characteristics under load, this paper carries out uniaxial compression and numerical simulation experimental research on fresh and weathered granite. The mechanical properties of fresh and weathered granite under uniaxial compression were analyzed, and the damage characteristics of weathered granite were revealed. Numerical models of different weathering degrees of the specimens were established based on FLAC3D, and at the same time, based on considering the distribution characteristics of granite microporosity, a random distribution model of weathered granite microporosity was established, and the deformation and damage laws of granite were obtained by numerical simulation. The results show that in the model considering the change of mechanical parameters of the rock in the weathering layer, the brittle tensile damage mainly occurs when the rock is not weathered. As weathering continues, the model undergoes brittle tensile and shear composite damage and gradually transitions to a damage pattern dominated by shear damage, which occurs when the rock strength deteriorates to about half of the fresh rock strength. In the model that jointly considers the mechanical parameters of rock microporosity and weathering layer, the microporosity affects the stress distribution to a certain extent, which leads to the change of the model strength and deformation damage characteristics. The damage form is closer to the real weathered rock damage, and the results of the study can provide a reference for the damage mode of weathered granite.

Mechanical properties of glass fiber-reinforced backfills under different proportion conditions

Zhao Kang, Yang Jian, Zhong Juncheng, Yan Yajing, Tian Xiangqin, Feng Yincheng

Archives of Civil and Mechanical Engineering

2024

Vol. 24, no. 3

art. no. e196, 2024

To investigate the mechanical properties of glass fiber-reinforced backfills under different proportion conditions, uniaxial compression tests were conducted on glass fiber-reinforced backfills with different slurry concentrations (65%, 68%, and 72%) and different cement–tailings ratios (1:6, 1:8, and 1:10). The effects of slurry concentration and cement–tailings ratio on the mechanical performance parameters, failure modes, and energy evolution of the glass fiber-reinforced backfills were discussed, and the effect mechanism of glass fiber on the overall mechanical properties of the backfills was revealed from a microscopic perspective. The results show that the slurry concentration and cement–tailings ratio have significant effects on the elastic modulus and uniaxial compressive strength of the glass fiber-reinforced backfill. The strength of the backfill reaches a maximum value of 2.831 MPa at a slurry concentration of 72% and a cement–tailings ratio of 1:6. The damage of the glass fiber-reinforced backfill under different proportion conditions first appeared in the central low-strength zone, and then gradually extended to the two ends, eventually leading to the overall failure. As the axial strain increases, the total and dissipated energies of glass fiber-reinforced backfill specimens increase as an exponential function, and the elastic energy increases and then decreases with the peak strain as the node. The bond between the glass fiber and the mortar matrix interface allows the fibers across both sides of the crack to form an “anchoring” effect, thus improving the overall properties of the backfill. The results of the study can promote the application and exploration of glass fiber-reinforced backfills in mine filling and provide some reference for improving the backfill performance.