Spatial distribution of inter-layer shear zones at Geobazhou dam site, Qingjiang River, China

摘要

The spatial distribution of inter-layershear zones is studied, based on the fully mapped inter-layer shear zones at the Gaobazhou dam site on theQingjiang River in Hubei province, China. The fieldobservations revealed that two types of inter-layershear zone, under-developed and well-developed, aredistributed differently. The former are associated withthe incompetent rock layers, and the latter arecontrolled by the inter-bed folds and lithologicalproperties of the strata. To represent their lithologicalproperties geomechanically, data on strength by theSchmidt hammer test and thickness of each field-identified rock layer were collected to form strengthsequences and thickness sequences. The adjacent rocklayers of similar strength are then grouped, and twogrouped sequences are combined into a single sequence,whose individual term is the strength weighted by theexponential function value of the centralized thickness(SCT). The rescaled range (R/S) analysis results ofSCT (SCT-R/S), taking into account the presence ofinter-bed folds, are in good agreement with R/Sanalysis results of the spacing sequence of the well-developed inter-layer shear zones. Thus the SCT-R/Smodel has the potential to predict their spatial distributions.