Dynamic characteristics and energy absorption mechanism of prestressed anchorage support

Abstract

In deep underground engineering construction and resource exploitation, complex conditions such as high stress and strong disturbance are often encountered, and dynamic disasters such as rockburst and coal burst are prone to occur. As a common anchorage support form in deep underground engineering, bolts and cables are often applied with high prestress to improve the bearing capacity of surrounding rock. It is the key to the reasonable support design of deep underground engineering to clarify the dynamic characteristics of prestressed anchorage support. Therefore, the dynamic impact test system of prestressed anchorage support is developed. Taking the commonly used high-strength (HS) support and the self-developed constant resistance energy-absorbing (CREA) support as the research objects, the dynamic impact tests are carried out. The test results show that applying high prestress significantly weakens the impact resistance and energy absorption capacity of anchorage support. Compared with the non-prestressed condition, the average impact force of HS bolt with 100kN prestress and HS cable with 250kN prestress is reduced by 56.2% and 43.3%, with energy absorption reduced by 17.8% and 19.6%, respectively. The average impact force of CREA bolt with 160kN prestress and CREA cable with 250kN prestress is reduced by 64.3% and 79.5%, with energy absorption reduced by 25.4% and 22.9%, respectively. The linear relationship between the energy absorption reduction rate and the strength utilization rate is revealed. The design method of anchorage support based on the strength-energy comprehensive criterion is proposed. The field application is successfully carried out in deep underground engineering influenced by dynamic pressure.