Research and application of mechanical characteristics of new lightweight high strength arch

Traditional steel arches have high weight, low bearing capacity, and high construction labor intensity, making it difficult to meet the safety and efficiency requirements of complex underground engineering. Taking the deep soft rock roadway as engineering background, a new type of lightweight and high strength arch is developed by using high strength and high toughness steel. The bearing capacity comparison tests of the new arch and the traditional U36 steel arch are carried out by using the full-scale arch test system, the deformation failure mode and bearing characteristics of the arches are clarified. In terms of arch steel performance,compared with the traditional U36 steel arch, the yield strength of the steel used in the new arch is increased by 97%, and yield elongation is increased by 41.9%. In terms of arch bearing characteristic,when the overall weight of the new arch is reduced by 33.3%, its ultimate bearing capacity is increased by 20.1%, the stable slip resistance is increased by 111.5%. In terms of deformation and failure characteristics,compared with the traditional U36 arch, the average in-plane deformation under ultimate bearing state is reduced by 16.4%, and the maximum strain position of the new and U36 arches is at the arch roof or leg. This indicates that the new arch has the characteristics of lightweight, high strength, high resistance, and stable slip. On this basis, the field application of the new arch is carried out, and the continuous monitoring results show that the average installation time of the new arch is reduced by 40.5% compared to the U36 steel arch. The maximum deformation of the new arch is 63 mm, the maximum stress is 101.3 MPa, and there is no obvious local buckling and out-of-plane instability, the safety reserve is high. The convergence deformation of surrounding rock is basically stable after 30 days, and the overall stress performance is roof,shoulder, waist. The new arch has good characteristics in bearing capacity and on-site construction efficiency, which provides a more lightweight and high-strength support form for the design of deep mine arch.