BLASTING, Volume. 41, Issue 4, 136(2024)
Experiment and Numerical Analysis of Crack Propagation in Mortar Blocks under Dynamic and Static Loads
To investigate the rock mass crack propagation pattern in deep-buried tunnels during drilling and blasting excavation, two combined model tests (labeled as Model 1 and Model 2) consisting of multiple cement mortar blocks were carried out. The dimensions of the models were both 180 cm×80 cm×25 cm (length width height). Among them, the matrix size was 60 cm×80 cm×25 cm, and two sides had single and multiple joints. Furthermore, a thorough analysis was conducted to determine the influence of dynamic loads stemming from nine cumulative explosions on the crack propagation in a matrix by applying various static stresses, particularly on the direction of the applied static loading. The experimental results reveal that cracks emerge on both Model 1 and Model 2 surfaces along the direction of static stress loading when the static stress increases from 0.5 MPa to 5 MPa. The crack propagation direction forms an angle on the loading direction, and the main crack is longer than 60 cm. A blasting funnel contour with about 30 cm diameter is formed on the bottom of Model 1, which does not fall off. In comparison, a funnel with about 52 cm diameter and a 10 cm depth is formed on the bottom of Model 2, which has fallen off. Numerical analysis verified that the static stress has a guiding effect on the propagation direction of blasting cracks, which is consistent with the model test results. The difference was that the length of the main crack calculated by numerical calculation was smaller than that of the model test. Finally, the reason for this deviation was analyzed.
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SHI Meng-meng, FAN Zhan-feng. Experiment and Numerical Analysis of Crack Propagation in Mortar Blocks under Dynamic and Static Loads[J]. BLASTING, 2024, 41(4): 136
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Received: Apr. 10, 2024
Accepted: Jan. 3, 2025
Published Online: Jan. 3, 2025
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