# Variable angle of insulated shotcrete under different loading rates and temperature and humidity cycles- shear test and analysis

## TL;DR

This study examines how thermal insulating shotcrete behaves under different loading rates and temperature-humidity cycles, focusing on its shear strength for deep mine applications.

## Contribution

The paper introduces empirical equations for shear strength parameters under thermal and mechanical stress in deep mining environments.

## Key findings

- Shear rate and peak shear stress initially increase then decrease with loading rate.
- Shear strength of thermal insulated shotcrete increases then decreases with temperature during cycles.
- Empirical equations for cohesion and internal friction angle were developed using MATLAB.

## Abstract

The new thermal insulating shotcrete is of great significance for the management of thermal damage in deep mines, and its own strength has a greater impact on the roadway insulation and safe production, so it is very necessary to study the shear strength of the new thermal insulating shotcrete under the influence of the deep hot and humid environment and the stress of mining. For the heat-insulating shotcrete, firstly, we carried out the concrete variable angle shear test under different loading rates, which concluded that the shear rate and peak shear stress showed a trend of increasing and then decreasing; as the angle increases, the different rates have a greater impact on the peak shear stress of the specimen. Secondly, the concrete variable angle shear test was carried out under the temperature and humidity cycle, which revealed that the shear strength of thermal insulated shotcrete increased firstly and then decreased with the increase of temperature at the same number of cycles. Finally, the empirical equations between the cohesive force c, the angle of internal friction ϕ and the number of warm and wet cycles n and the temperature of warm and wet cycles T are fitted with the MATLAB software respectively, and the research results provide technical references for the management of geothermal temperature in deep well projects.