A Deforming Characteristic Evaluation Of Excavating Underground Hydropower Station On The Right Bank Of The Three Gorges Project

The underground hole room project is generally constructed several dozens meters even over a hundred meter depth underground, and the scale is getting larger and larger, the spatial arrangement is getting more and more complex, therefore it is important to analysis the adjacent formation structural stress distortion. This article is based on nonlinear finite element rationale, simulated Three Gorges right bank underground power plant hole room group excavation by MSC.MARC finite element analysis software and analysised hole room strain rule.This article summarized the stability of the wall rock and the mutual influence to the hole room groups systematically. Described the engineering general situation and the geologic condition of the research zone, introduced the elastoplasticity submitted the theory, the finite element analysis method as well as the MSC.MARC software, elaborated the research area project survey and the geological condition in detail.To establishment the underground hole room plane strain mechanical model using the MARC finite element software, firstly,establishes finite element model which three hole room parallel arrangement excavates, adjustment hole room size, analysis hole room group size to hole room adjacent formation strain influence.Secondly,carries on one time excavates and the lamination excavates the simulation, carries on the analysis comparison to two kind of plan computed result, discovers the respective good and bad points.Collceting the rock deforming monitoring outcome in the process of excavation about Three Gorges main plant,and contrasted analyzing with the calculated outcome in the previous description,we can illustrate the axaction of the research findings.Main conclusions:1. The distortion of the mass of underground room is affected by the distance of each other. The distortion increases rapidly when the distance is less than 2 times of the room's width. This indicated that the affecting scope of excavation is twice width of the room under the cause of this paper.2. If excavation is done in a short time, the stress and yield zone is larger than that when the excavation is preceded in many steps. But the displacement is smaller in later case. However, the difference is very little.3.As exacavating from the top of hole to the bottom, the side walls of underground hole deform to the inner of the hole. the direction of vertical distortion of the crown is upside at first and then the direction is downside.4.The maximal horizontal displacement of edge wall is appeared in top corner of grotto during the first period of excavating, and the relative height is 1.0. When the excavation altitude is as high as the width of chamber, the relative height reduces to 0.5. The value is reducing when the excavation goes on and finally steadied at 0.38.