Abstract:The surrounding rock of surge-shaft in proposed Hydropower Station contains mainly quartz mica schist

After exploration and laboratory tests

It found that the rock belongs to soft rock

which has obvious schistosity structure and typical transverse isotropic rheological characteristics. The rheological behavior of surrounding rock during construction and operation may significantly affect the stability of rock mass and the characteristics of lining structure due to the high level of regional crustal stress. In this paper

Through comprehensively reflecting regional geological structure

structure of the surge shaft and stress fields

A three dimensional numerical calculation model is established with considering the construction sequence and supporting lining measures

according to Viscoelastic plastic damage constitutive model of transversely isotropic rock mass based on laboratory test and field monitoring data

Study on the stability of surrounding rock and lining structure safety of the surge-shaft group during construction and operation by using FLAC3D. The results show: Under the influence of rheological effect of the surrounding rock in the process of construction excavation

Deformation of the surrounding rock increases with time

The effect of anchor support on the deformation of surrounding rock is obvious. After 500d excavation

the displacement of surrounding rock tends to converge; the surrounding rock is in a state of compression after excavation

The two times lining is conducive to the distribution of the stress field of surrounding rock. The value of the growth rate of surge shaft lining deformation gradually decreased with time during operation

The deformation of the 2 year is about 54% of the deformation of the long term (50 years). The stress level of surge shaft lining structure and surrounding rock tends to be stable after 1 years of operation. During operating period

The variation range of stress level of surrounding rock of surge-shaft is very small.