Experimental Development and Investigation of Grouting Reinforced Rock for High Geo-Temperature Environment

Abstract

ABSTRACT With the increase of long and deep-buried tunnels, the disaster caused by high geo-temperature was more and more prominent. Grouting reinforcement was an important tunnel support measurement. Therefore, this study was aimed at an investigation of grouting reinforced rock under the high geo-temperature. Firstly, a new experimental device for grouting reinforced rock was designed, which could be used for laboratory tests under simulate different geo-temperature. Then, an experiment of grouting reinforced rock under different temperatures (20, 30, 40, 50, and 60°C) was carried. Finally, the results indicated that the newly developed device was applicable for the physical and mechanical properties investigation of grouting reinforced for broken rock under different temperatures, which also had the advantage of small size and flexible installation. The strength, ultrasonic velocity, and permeability resistance of grouting reinforced rock first increased and then decreased with temperature, which had an optimal value at the temperature 30°C. In addition, the positive correlation among the strength, ultrasonic velocity, and permeability resistance under different geo-temperature was also demonstrated in this paper. It was expected to make a reference for the tunnel grouting reinforcement design under the high geo-temperature environment. INTRODUCTION With the advancement of tunnel design and construction technology, the number of deep-buried long tunnels crossing geologically active areas increases. The high geo-temperature phenomenon (temperature exceeding 28°C during construction operations) is presented in deeply-buried long tunnels, which is due to hydrothermal activity, active fractures, and magmatic activity (Sun et al., 2021). For example, the length of high geo-temperature region accounts about 1/3 of the Gaoligong Mountain Tunnel in China, and the highest geo-temperature is about 50°C (Du et al., 2021). There are more than 10 high geo-temperature tunnels along Sichuan-Tibet Railway. The high geo-temperature not only deteriorats the construction environment but also seriously damages the performance of support materials and surrounding rock stability (Chen et al., 2022; Sun et al., 2022). Therefore, the investigation of support materials under different geo-temperature is imperative.