Introduction

Shale is widely distributed in the Earth’s strata and has received extensive attention in the fields of mineral resource extraction (e.g., shale oil and gas extraction) and underground space resource utilization (e.g., soft-rock tunnel support, CO2 geologic sequestration, radioactive nuclear waste, etc.). Shale is a rock formed by dehydration and cementation of clay, which is dominated by clay minerals and has an obvious laminated structure. Its mechanical strength tends to be low, and it is susceptible to softening and swelling when exposed to water, with poor stability. The study of the physical and mechanical properties of shale is of great significance to the safe mining and efficient utilization of minerals and underground space. However, due to the complexity of shale’s own structure and the limitation of testing technology, the past has mostly focused on small-size samples’ full load destructive measurements, which are difficult to use to respond to the influence of complex structure on mechanical properties. In addition, the specimen sampling requirements are higher, the test results are more discrete, and multiple experiments are needed to ensure the reliability of the results, which makes it difficult to form a continuous and trendy understanding. At the end of the experimental test, the specimen is completely destroyed, the core consumption is large, and the economic cost is high. In recent years, with the development of non-destructive and micro-destructive scratch test technologies, it has become possible to study the characteristics of spatial continuity changes in the mechanical properties of shale. This book focuses on some research results of macro- and micro-scratch mechanical tests and numerical simulations of shale, in order to provide a reference for understanding and recognizing the macroscopic mechanical properties of shale.