Micro-macro evolution of mechanical behaviors of thermally damaged rock:A state-of-the-art review

The influence of thermal damage on macroscopic and microscopic characteristics of different rocks has received much attention in the field of rock engineering.When the rocks are subjected to thermal treatment,the change of macroscopic characteristics and evolution of micro-structure would be induced,ultimately resulting in different degrees of thermal damage in rocks.To better understand the thermal damage mechanism of different rocks and its effect on the rock performance,this study reviews a large number of test results of rock specimens experiencing heating and cooling treatment in the laboratory.Firstly,the variations of macroscopic behaviors,including physical parameters,mechanical parameters,thermal conductivity and permeability,are examined.The variations of mechanical parameters with thermal treatment variables(i.e.temperature or the number of thermal cycles)are divided into four types.Secondly,several measuring methods for microstructure,such as polarizing microscopy,fluorescent method,scanning electron microscopy(SEM),X-ray computerized tomography(CT),acoustic emission(AE)and ultrasonic technique,are introduced.Furthermore,the effect of thermal damage on the mechanical parameters of rocks in response to different thermal treatments,involving temperature magnitude,cooling method and thermal cycle,are discussed.Finally,the limitations and prospects for the research of rock thermal damage are proposed.

Guidance and review:Advancing mining technology for enhanced production and supply of strategic minerals in China

Mineral resources,often referred to as“industrial food,”play a pivotal role in the national economic construction sector.Specifically,strategic minerals(SMs)bear a direct influence on the development of emerging strategic industries within China.This paper aims to shed light on the supply and demand dynamics,current status,and characteristics of SMs from the perspective of China's national security.We offer a comprehensive review of the current status and challenges associated with SM mining technology in China.Our analysis spans various mining methods,including open-pit mining,deep underground mining,green mining of complex underground bodies,integrated underground mining and processing,and intelligent mining.Within this framework,we delve into multiple initiatives aimed at improving the status of the mining industry,increasing production,and maintaining the adequate supply of these resources.We discuss these strategies from both a top-level policy and system design perspective,as well as detailed implementation plans.