Research On Dynamic Feedback And Control For Rock Stability Analysis Of Large Underground Cavern Group During Construction Period

Due to various effects by the diversity of geological conditions,hydrological conditions and load conditions,the engineering of underground cavern group is in a complex environment which is inducing hazard,so the slope failure problem is a set of complex,highly uncertain and dynamic nature of systemic problems in one,involving a wide range,covering more content.Especially,engineering accidents caused by instability of surrounding rock is quite common.Naturally,the feedback and control for rock stability analysis of large underground cavern group become problems demanding prompt solution during construction period.Based on the underground cavern at the Huangdeng hydropower station,research on dynamic feedback and control is carried out for rock stability analysis of large underground cavern group during construction period in the dissertation.A scientific and practical flowchart of dynamic feedback and control for rock stability analysis of large underground cavern group during construction period is founded,which includes several important components: three-dimensional inversion analysis of an in situ stress field based on a two-stage optimization algorithm,dynamic inversion analysis of mechanical parameters,feedback and control for rock stability analysis under poor geological conditions and dynamic safety information model of underground cavern group during the whole construction period.Correlative methods and technologies are empathically studied or summarized.The main contents and results are as follows:(1)A scientific and practical flowchart of dynamic feedback and control for rock stability analysis of large underground cavern group during construction period is founded,which includes the following steps: estimating the in situ stress field,evaluating mechanical behavior of surrounding rock after excavation of the previous period,checking basic information and mechanical behavior of surrounding rock after excavation at the present stage,dynamic controlling measures for poor geological conditions during the current period of excavation,evaluating the rock stability after excavation at the current stage,dynamic inversion analysis of mechanical parameters during the current period of excavation,predicting mechanical behavior of surrounding rock in the next stage of excavation and closing loop feedback until the construction of the underground cavern group is finished,which means the process of dynamic feedback and control of the underground cavern group during the construction period is over.(2)A two-stage optimization algorithm proposed in this paper is a combination of stepwise regression,difference evolution,support vector machine and numerical analysis techniques,and then the distribution of the in situ stress field at the Huangdeng engineering site was successfully obtained after optimal boundary conditions from it were input into a numerical calculation model for elastic-plastic finite element analysis,which produces a more realistic estimate of the stress distribution within the investigated area.Thus,this technique may have practical applications in realistic scenarios requiring efficient and accurate estimations of the in situ stress in a rock-mass.(3)Based on considering the information of excavation progress,support progress and newly outcropped geology in construction site,the three-dimensional numerical simulation model is established,with the dynamic numerical calculation of the mechanical parameters of surrounding rock of underground cavern group is introduced,and the process of dynamic inversion analysis of mechanical parameters is established.So the coupling between geometric parameters,dynamic mechanical parameters and dynamic updating of construction information is realized,and spatial and temporal characteristics of the surrounding rock mechanical parameters are revealed.(4)The monitoring information of poor geological regions is particularly analyzed for the underground cavern group of Huangdeng hydropower station,and the three-dimensional model for stability analysis of the surrounding rock is established.In order to ensure the safety construction of underground cavern group under poor geological conditions,the analysis method system for the stability of surrounding rock in the construction period is studied based on the underground cavern group project of Huangdeng hydropower station,including recognition of failure mode for surrounding rock and dynamic controlling measures,feedback analysis of monitoring information and numerical simulation analysis of underground cavern group.(5)The dynamic safety information model of underground cavern group is actually established during the whole construction period through the mixed programming technique,considering the dynamic information in the construction process of underground cavern group.Finally,it realizes the visualization management for monitoring information of the underground cavern group in Huangdeng hydropower station,the dynamic coupling visualization of the construction features and the safety status and the dynamic updating of the construction information with the construction progress,coupling visualization technology,monitoring analysis method,parameter inversion theory,numerical simulation method and computer technology.