Abstract
With the effects of high geostress and intensive dynamic disturbances in deep mining, the stability and safety of tunnels are seriously affected. The optimization for U‐shaped steel support is of vital significance and can solve the problems of cost reduction and tunnel instability. Based on the perturbation equation, a coupled formula for U‐shaped steel and the surrounding rock mass was proposed to evaluate the practical stability of a U‐shaped steel support. Through a numerical simulation method, the characteristics of U‐shaped steel support can be obtained under coupled static‐dynamic loading. Furthermore, the field test was carried out and compared with the numerical simulation, which was discussed. The results show that there will be a stress concentration when the contact area is small. In addition, the concentrated stress will release with the increase in contact area. With the increase in the lateral stress coefficient, the deformation exhibits a downward trend under static loading, indicating that the lateral stress is the dominant force driving the deep geostress activity. The support requirement of this section of surrounding rock can be satisfied by a U‐shaped steel group with 1.5 m spacing under dynamic disturbance.
Highlights
Due to the severe situation in the mining market in recent years, all mining enterprises are further reducing the cost and increasing efficiency, and the cost of tunnel support accounts for a large proportion of the cost of mine production materials
If the support forms and parameters of the tunnel are not chosen properly, it will cause two extremes: one is the high intensity of support, which will cause high support costs and affect the speed of excavation. e other is that the strength of support is not enough to effectively control the deformation of surrounding rock, and safety accidents can occur such as roof fall
How to reduce the support cost under safe conditions has become a new topic in the production of enterprises
Summary
Due to the severe situation in the mining market in recent years, all mining enterprises are further reducing the cost and increasing efficiency, and the cost of tunnel support accounts for a large proportion of the cost of mine production materials. Cao et al [19] put forward a bolt support method for tunnels that can reduce surrounding rock deformation through optimization of bolt parameters and arrangement, floor beam layout, and full-length grouting These technologies have the advantages of low support costs and improved support effects, most of them have the disadvantages including the low support strength, antibending capacity, and difficult applicability, which are prominent [20, 21]. The factors including support spacing, side stress coefficient, dynamic disturbances, and contact area between U-shaped steel and surrounding rock are not comprehensively considered in the previous research, . With the considerations of different support spacings, side stress coefficients, contact area ratios, and dynamic disturbances, the stability of surrounding rock and the support effect of U-shaped steel were comprehensively researched. The optimal support spacing of U-shaped steel was solved with the combination of stress concentration factor. is paper is expected to provide theoretical guidance for the U-shaped steel support of deep tunnels, which can improve tunnel stability and reduce support cost
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