Effect of Water Content on Dynamic Fracture Characteristic of Rock under Impacts
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pISSN 1226-7988, eISSN 1976-3808 www.springer.com/12205
DOI 10.1007/s12205-020-2249-6
Geotechnical Engineering
Effect of Water Content on Dynamic Fracture Characteristic of Rock under Impacts Caoyuan Niu
a
, Zheming Zhu
b
, Fei Wang
b
, Peng Yingb, and Shuai Dengc
a
State Key Laboratory of Hydraulics and Mountain River Engineering, School of Architecture and Environment, Sichuan University, Chengdu 610065, China MOE Key Laboratory of Deep Underground Science and Engineering, School of Architecture and Environment, Sichuan University, Chengdu 610065, China c Failure Mechanics & Engineering Disaster Prevention and Mitigation, Key Laboratory of Sichuan Province, Sichuan University, Chengdu 610065, China b
ARTICLE HISTORY
ABSTRACT
Received 5 December 2019 Revised 16 June 2020 Accepted 14 August 2020 Published Online 9 November 2020
Water contents in rocks vary with local hydrogeological conditions and may significantly affect the stability of rock mass engineering. For example, geological disasters are usually occurring after rainfall, such as landslides, karst collapse. In this paper, drop plate impact (DPI) tests were performed on single cleavage triangle (SCT) red sandstone specimens with dry, natural, absorbed and saturated conditions, which has a great guiding significance for deep understanding of dynamic failure of rock materials. The crack initiation time was obtained by crack propagation gauges (CPGs), and crack propagation speeds were computed by fractal method. The dynamic stress intensity factors (DSIFs) were calculated by ABAQUS code. Meanwhile, the microstructure of the fracture surface was scanned and was analyzed. The results show that the average critical DSIFs and crack propagation speeds vary with water content significantly. For the dry sandstone, the average critical DSIF is the highest, whereas the average crack speed is the lowest. For the natural sandstone, the average critical DSIF is the lowest, whereas the average crack speed is the highest. For the water-bearing sandstone, i.e., the natural, absorbed and saturated sandstone, the average critical DSIF increases with water content, whereas the crack speed decreases with increasing water content.
KEYWORDS Water content Dynamic stress intensity factor Crack propagation speed Fractal Roughness
1. Introduction Rock usually contains water and the water content depend on local hydrogeological conditions, such as rainfall, river and groundwater. Meanwhile, rock usually contains a plenty of cracks. As the water-bearing cracked rock is subjected to dynamic loads, such as impacts, blasts and earthquakes, the cracked rock dynamic response will be very complicated. The cracks may propagate and weaken rock structure stability, which may induce large geological disaster, such as landslides and rockbursts (Ma et al., 2016). Hence, the corresponding experimental and numerical studies on the responses of water-bearing cracked rock under dynamic loads are very important. In the study of the impact of water on rock mechanical properties, conside
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