Deformation mechanism of surrounding rock in deep soft rock roadways and a coupled support approach

In deep high-ground stress soft rock roadways, the surrounding rock often deforms extensively with rapid convergence and long-term continuous deformation. Through strata behavior monitoring, geological radar penetration, rock mineral composition analysis and ground stress measurement, the surrounding rock deformation characteristics and mechanism were investigated. Based on the investigation, we propose in this paper a novel high-strength dynamic coupled support approach that centers around high-strength high-pre-stress anchor bolts, grouting bolts (cables), and U-shaped steel shelves. In addition, a stepwise support mechanism is detailed. In order to validate the proposed support approach, the numeric difference software FLAC3D was used to simulate, compare, and analyze the surrounding rock deformations and elastic area scales when using the original and the new support approaches. The analyses showed that the proposed approach effectively controls the development of elastic areas and reduces surrounding rock deformation. Field application of the approach demonstrated consistent result with the numeric calculation. Comparing with the original support, the new approach reduced the scale of loosening damage by about 50%; the roof subsidence, wall-to-wall convergence, and floor heave were controlled to only 145, 134, and 62 mm, respectively, demonstrating the approach's good support performance. © 2015 ejge.