As a kind of existing and potential geological disaster at source of avalanche on cliffs or steep slopes, perilous rock has developed in the western area of China widely and it poses a serious threat to highways, railways, pipelines, cities, and mining for a long time. More than ten years of engineering experience have shown the necessity and importance to pay our attention to the avalanche sources in active collapse mitigation. The support - anchor combined technique is devoted to the active hazard mitigation measures of perilous rock. This paper introduces fracture mechanics to investigate the design procedure of the support - anchor combined technique. To obtain reasonable design parameters of the technique, both stability assessment criterion and three safety classes of protection engineering for perilous rock is proposed, further, stable analysis methods for various types of perilous rock are established by using fracture mechanics. Abiding by the idea that to improve stability coefficient to a higher level, the support force of structure and the anchorage force of anchorbolt from the support - anchor combined technique are introduced into stability analysis methods established above, which can estimate the section dimension of support subunit and the amount of anchorbolt of the technique. Engineering applications of the technique in thousands of protection engineering have identified the remarkable effectiveness.
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