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pISSN 1226-7988, eISSN 1976-3808 www.springer.com/12205

DOI 10.1007/s12205-020-0572-6

Geotechnical Engineering

Investigation on Mechanical and AE Characteristics of Yellow Sandstone Undergoing Wetting-Drying Cycles Yaoyao Menga, Hongwen Jinga, Qian Yina, and Xiaowei Gua a

State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221116, China

ARTICLE HISTORY

ABSTRACT

Received March 28, 2020 Revised May 30, 2020 Accepted June 26, 2020 Published Online 10 September 2020

The cyclic wetting-drying phenomenon is a complicated physical and chemical process. This kind of process will weaken the properties of rock to some extent. Some fundamental physical parameters of sandstone were first tested to study the weakening influence of wetting-drying cycles on the physical characteristics. Then, the water weakening effect on the mechanical and acoustic emission (AE) characteristics of rock on account of wetting-drying cycles was experimentally studied. Laboratory test results showed that when the number of cycles increased from 0 to 25, the density, P-wave velocity, uniaxial compressive strength (UCS), (elastic modulus (E)) and total AE counts of the rock specimens continuously decreased. However, the water absorption would increase as the number of cycles increased. The functional relationships between the total AE counts and the mechanical parameters (UCS and E) of sandstone after each cyclic number were established based on the test results. In addition, the chemical components and microstructure variations of rock undergoing wettingdrying cycles were examined. From the results, it can be concluded that microcrack growth and expansion inside the rocks undergoing wetting-drying cycles are the main reasons for the attenuation of the rock properties. Moreover, with increasing loading rate, the UCS, E and total AE counts of sandstone after each cyclic number would increase.

KEYWORDS Sandstone Wetting-drying cycles Mechanical properties AE characteristics Loading rate

1. Introduction Rock masses in actual engineering applications are periodically subjected to moist conditions. In these rock engineering applications, the rock’s deterioration is closely related to the presence of water. The actions of wetting-drying cycles on the rock can be initiated by daily, seasonal and even yearly variations in the rainfall, humidity, and underground water level. These actions can accelerate the weathering process of rock. The water in the rock can also cause crack initiation, propagation, and coalescence, which may further accelerate the damage of rock (Zhou et al., 2018b; Zhou et al., 2019; Zhou and Zhuang, 2020; Zhou et al., 2020; Zhuang et al., 2020). Finally, many geological hazards, such as deformation of the building foundation, pillar degradation and landslides can occur over the time. Therefore, studying the wetting-drying cycle attenuation of the physical and mechanical characteristics of rock is of important significance. In the last few years, scholars have