| Deep anti-sliding stability of dam foundation is one of the widely concerned issues in gravity dam construction. The formation section of Wudu reservoir area, whose dam belongs to gravity dam, locates at the northern drape zone of Longmen mountain. The geological formation of the dam area is very complex. Furthermore, the structure discontinuous planes with low dip angles of considerable scale are in a large number. The combination of these structure discontinuous planes result in an eminent problem in the Deep anti-sliding stability of the dam foundation. Based on the outdoor investigation on the structure discontinuous planes of the dam foundation and statistic analysis of the structure discontinuous planes of the excavated slope, a geological model of the rock structure has been established and an assessment on the controlling functions on the deep sliding, which the rock structure around the dam has has been made. The slippage pattern of the dam foundation has also been analyzed. Reasonable estimation on the geological model is then conducted. Employing digital simulation and rigid equilibrium limit method, the paper studies the sliding pattern of Wudu reservoir dam foundation and the stability of the dam foundation with some reinforcement measures provided. The major studies are as follow.Firstly, based on the analysis of engineering geological conditions, including the scale of the structure discontinuous planes, the engineering geological properties and the significane of engineering geology, and the situational conditions of the dam area, the structure discontinuous planes around the dam area are classified into five classes and two major categories (Three sub-categories are also set as the soft structure discontinuous planes are concemed).Secondly, an investigation of the structure discontinuous plane of the dam area, a three-dimension laser scanning analysis, and an analysis of the relevant data from a survey have found out the spatial distribution and the variation of the spatial properties as F31 fault of the classâ…¡structure layer is concerned. The range, where fault f101, 10fs, f27, F31-1, and f114 in classâ…¢andâ…£structure layer expose in the dam area, and their substantial compositions have been found out and their properties have been sectioned. In addition, knowledge of the inter-layer mobile zone, extension length and the properties of the grown crannies have been obtained. Furthermore, the distribution patterns and connection rate of the basic crannies have been calculated and a rock structure model has been established.Thirdly, having analyzed the substantial geological data, the paper argues that the major possible deep-plane sliding patterns of the dam foundation rock body are double-faced sliding pattern of instability, multi-section sliding planes pattern of instability, and spatial block body pattern of instability. The major incision planes are fault F31, fault F31-1, fault 10f2, inter-layer mobile zone and steep obliquity cranny at the dam heel. The primary sliding-control planes include f101, f115, and f114, and the minor sliding-control layer is the cranny of low-middle dip angles.Fourthly, employing digital simulation method in analyzing the displacement, block state area, shear strain increment, the sliding pattern of the dam foundation has been validated. An assessment on the integral and partial stability of the dam foundation has also been made.Fifthly, a calculation formula of random multi-sliding planes has been deduced in accordance with the theory of rigid equilibrium limit method among dam foundation deep plane anti-sliding. A corresponding computing software has also been programmed. Having computing the stability of typical dam sections, a quantitative assessment has been made.Sixthly, As far as the structure discontinuous planes which often result in deep sliding are concerned, such means as high pressure grouting, removing, replacement are suggested.The comprehensive analyses above indicate that dam foundation rock body of Wudu reservoir is complex in structure and the deep-plane anti-sliding problem is evident, therefore the soft structure planes need further construction. Keywords: Wudu reservoir, rock structure characteristic, sliding pattern, rigid equilibrium limit method, stability analysis...
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