In recent years, the development and application of underground space has made rapid progress, for example, the subway, tunnel, and mining industries. One of the main support means to maintain the stability of surrounding rock in underground space is shotcrete, which is convenient and easy to operate. Shotcrete support is widely used in the construction of subways, tunnels and mine roadways. Due to the high concentration of dust produced by dry shotcrete technology, it is gradually being replaced by wet sprayed concrete technology.

However, the wet sprayed shotcrete technology is facing problems, such as pipe blockage, high rebound, and low adhesion. In the process of underground space development, extreme geological conditions such as high ground stress and high temperature easily lead to the deterioration of shotcrete, which affects the support effect. Experts at home and abroad have tried to improve the performance of shotcrete by optimizing the proportion of shotcrete, adding reinforcement materials (such as polymer, fiber, etc.), and changing the mixing process, to delay the deterioration of sprayed concrete and improve the support performance of concrete. It is of great significance to study the failure mechanism of shotcrete support for improving the support quality of concrete.

The purpose of this Special Issue is to invite original research articles and reviews focusing on the deterioration mechanism and improvement measures of shotcrete support materials in underground space.

Potential topics include but are not limited to the following:

• Failure characteristics of shotcrete under high ground stress
• Failure mechanism of shotcrete in high temperature environment
• Sealing effect of shotcrete in the process of support
• Dynamic failure characteristics and constitutive properties of shotcrete
• Mechanical behavior of modified polymer-based shotcrete
• Variation law of surrounding rock under dynamic disturbance
• Rheological properties and pipeline transportation characteristics of fresh shotcrete
• Adhesion characteristics of shotcrete on surrounding rock
• Advanced shotcrete improvement technology and surrounding rock control method