Thermal effect on wave velocity of sandstone after high-temperature treatment: a review
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REVIEW PAPER
Thermal effect on wave velocity of sandstone after high-temperature treatment: a review Jianjun Hu 1,2 & Xiaohua Pan 2,3 & Weiqiang Zhang 4 Received: 11 June 2018 / Accepted: 11 October 2019 # Saudi Society for Geosciences 2019
Abstract Variations in wave velocity and porosity of sandstone after high-temperature treatment are investigated. The results for normalized wave velocity and porosity show that 400 °C is the critical threshold temperature of sandstone. Below 200 °C, porosity increases slowly as the treatment temperature increases, while wave velocity gradually decreases. When the temperature is higher than 400 °C, porosity quickly increases, and wave velocity sharply decreases. The “room temperature–200 °C” and “200–400 °C” temperature ranges correspond to the undamaged state and the microdamage state, respectively. Keywords Temperature . Sandstone . Porosity . Wave velocity
Introduction In recent years, many scholars have studied the effect of temperature on rocks (Chen et al. 2016; Jia et al. 2019; Li et al. 2019; Sun et al. 2019; Shen et al. 2019). It is assumed that physical and chemical reactions under high-temperature conditions or after high-temperature treatment lead to the occurrence of interstitial and melt film, which likely affect the physical and mechanical properties of rock. These reactions are closely related to the mineral composition of rock and can be initiated at different temperatures in the heating process.
Responsible Editor: Abdullah M. Al-Amri * Jianjun Hu [email protected] * Xiaohua Pan [email protected] 1
College of Water Resource and Hydropower, Sichuan University, Chengdu 610065, China
2
Institute of Deep Earth Sciences and Green Energy, Shenzhen University, Shenzhen 518061, China
3
School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
4
School of Resources and Geosciences, China University of Mining and Technology, Xuzhou 221116, China
Research on thermal damage based on variations in porosity and wave velocity of rock is extremely useful when the physicochemical conditions of intergranular reactions and the formation of interstitial phases and their effects on rock properties are not well understood. Under the influence of high temperature, new microcracks generate in the rock, and pre-existing cracks extend/widen (Chakrati et al. 1996; Dwivedi et al. 2008). In the heating process, the development of various physical and mineralogical changes may lead to thermal damage. However, during cooling, some thermally induced changes are reversible to some extent (Tian et al. 2012). In most rocks, cracks or porosity plays an important role, and key information about changes in cracks or porosity in rocks may be reflected in wave velocity (Sun and Zhu 2014). It is generally accepted that the wave velocity of rock decreases with increasing temperature both during and after high-temperature treatment (Somerton 1992). Sandstone is a common type of sedimentary rock that has broad applications in geotechnical engineering, such as the
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