Research on influence of disturbed belt on stability of surrounding rock of large-scale underground caverns

The interlamination disturbed belt which gets through Baihetan hydropower station underground caverns, with the characters low-angle dip and perfoliate, is derived from vary top of tuff. In fact, it is a disturbed shear zone blending cataclasite and mudstone under complicated geological process. As its formation process and internal structure are relatively complicated, it is difficult to descript its mechanical behavior. In order to reveal its mechanical properties more intuitively and reasonably, its geological structure is considered as a 'sandwich biscuit' which contacts upper and lower and clamps weak belts in the interlayer. Based on field test, FLAC is used to analyze its mechanical properties; and the acquired rules and calculation parameters are used to analyze the surrounding rock of underground caverns. The shear strength margin balance theory is used to analyze the influence of disturbed belt on the surrounding rock of underground caverns in order to provide support method and support parameters for the underground caverns.