| Summary: | To prevent large tunnel deformations caused by the rock bursts or the squeezing ground conditions, the rock bolts used should satisfy both strength capacity and the required deformability. Currently, the energy-absorbing rock bolts, such as the cone bolt and D bolt, have been successfully utilised in the deep mining to avoid sudden tunnel collapses. However, a rigid type rock bolt (e.g. a fully grouted rock bolt) is still commonly used in civil engineering tunnels even when they are excavated under a high overburden pressure with poor geological conditions. In such cases, the rock bolt might fail in tension due to the large deformation. This paper proposed a new energy-absorbing rock bolt, which is referred to as a deformation-controlled rock bolt (DC-bolt). The performance of the proposed DC-bolt was verified by the numerical simulations using the discontinuous deformation analysis (DDA) and by the prototype laboratory tests. This study concluded that the DC-bolt possesses both the high loading capacity and the deformable capacity. Additionally, the DC-bolt can limit the rock surface movement when it reaches a certain displacement, thus, it can be a useful tunnel support for civil engineering tunnels excavated under the squeezing ground condition.
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