Abstract：Based on the results of uniaxial，triaxial and acoustic emission tests carried out on basalt at Baihetan hydropower station，the pre-peak characteristic strength and post-peak mechanical behavior of basalt are discussed. The crack initiation strength of basalt is about 0.5–0.6 times of the peak strength，while the damage strength is close to the peak strength. There are obvious brittle and dilatant behaviors during failure process，and post-peak mechanical behaviors are nearly uncorrelated with the confining pressure. The conversion relationship between the plastic flow coefficient ? in Hoek-Brown constitutive model and the rock dilatancy angle ? is established，and the applicability of Hoek-Brown model for describing post-peak brittleness and dilatancy of basalt is demonstrated. Engineering application shows that the influence of dilatancy characteristics of the surrounding rock on its stability is closely related to the stress path of excavation response. In the stress concentration area，the stronger the dilatancy is，the more unfavorable to the stability of the surrounding rock. Due to that the stress relaxation area lacks the level of concentration stress required for triggering dilatancy，dilatancy is not the critical factor of control stability. In the practice of deep-buried cavern in brittle rock mass in underground engineering，it is suggested that differential support design schemes should be formulated for side wall and vault according to mechanism of excavation response.
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2019, Vol. 38 
