Experimental and numerical research of crack propagation process and energy dissipation law of grouting specimens under radial impact load

Abstract

Different air pressures are used to conduct an impact test based on the split Hopkinson pressure bar (SHPB) test system to study the crack evolution process and energy dissipation law of the cemented rock under impact load. The failure mechanism of the specimens is analyzed from the perspective of dynamic failure process and energy dissipation. The spatial distribution of the specimen components visualized by the image reconstruction technology and the LS-DYNA mesoscopic model is established. Results show that the proportion of dissipated energy, the dynamic tensile strength and peak strain of the specimens increase with strain rate increase. The crack evolution process of the model is quantitatively described under an impact load, which is divided into four stages, namely, no crack stage, slow development stage, accelerated propagation stage and penetration stage. Compared with the indoor and simulation test result, the crack evolution process and failure modes are consistent under different strain rates. When the specimens are destroyed, the energy dissipation rate fluctuates from 10% to 13%. The dissipated energy of cement paste accounts for more than 90% of the total dissipated energy. The cement paste damages first and its strength has a great influence on the strength of the grouting specimens. This study provides a reference to evaluate the cemented rock under a dynamic load.

Review of SHPB Dynamic Load Impact Test Characteristics and Energy Analysis Methods

“…The incident wave is then shaped from a rectangular wave to a sinusoidal wave, reducing the transverse inertia effect and the dispersion of the stress wave over long distances. For the selection of pulse-shaping materials, scholars mostly use copper sheets (brass and red copper) with different thicknesses and shapes (circular sheets and ring-shaped sheets) as shapers to achieve dynamic mechanical property analyses of various materials [9,[38][39][40][41][42][43][44][45][46][47][48][49][50][51]. New materials such as aluminum alloys, medical tapes, cardboard, rubber, and asbestos flakes are gradually being used in the pulse-shaping technique in response to the diversity of dynamic mechanical properties of materials [52][53][54][55][56][57][58][59].…”

“…The SHPB test technique was initially used to study metallic materials. With the development of material dynamic test technology and the increase in material diversity, the SHPB test technique's research objects have been expanded to brittle materials, soft materials, foam materials, polymer materials, and composite materials, which have been applied in various fields [1][2][3][4][5][6][7][8][9][10]. In addition to the conventional dynamic compression test, the dynamic tensile properties and crack propagation laws of materials can also be studied using the dynamic Brazilian disc split tensile test, which has a different loading mode compared to the former [11][12][13][14][15][16][17][18].…”

New experimental investigation of 3D cracks propagation in mortar under tension loading

“…Several strategies for healing the cracks are experimented on using Epoxy Resin, Carbon Fibre Reinforced Polymers, Bonded Overlays, Micro bacteria, and Electrochemical solution [3]. In 2023 [4], an experimental and numerical study of the crack growth in specimens under radial impact load provided a reference to evaluate the cemented rock under a dynamic load. A Micro-encapsulated bacterial spore was employed as an additive substance to self-repairing the shrinkage crack in mortar [5].…”

New experimental investigation of 3D defects propagation in mortar under tension loading

“…Several strategies for healing the defects are experimented on using Epoxy Resin, Car-bon Fibre Reinforced Polymers, Bonded Overlays, Micro bacteria, and Electrochemical solution (Bano et al, 2023). In 2023 (Zhu et al, 2023), an experimental and numerical study of the defect growth in specimens under radial impact load provided a reference to evaluate the cemented rock under a dynamic load. A Micro-encapsulated bacterial spore was employed as an additive substance to selfrepairing the shrinkage defect in mortar (Nuaklong et al, 2023).…”