Numerical Simulation And Study On Blasting Excavation Of Underground Powerhouse Of Hydropower Station

In the construction of many huge hydroelectric engineering, there are many underground engineering such as diversion tunnel, access tunnel, test direct tunnel, grouting tunnel, large-scale underground cavern group and so on.Because of development of energy,traffic and national defense, especially, the development of hydropower, make the scale of large-scale and ultra large-scale underground project already become the main direction of development. With the increase of the capacity of hydropower station, the scale of underground powerhouse and the relevant cavern group are larger and larger, characterized of large span, high sidewall, multiple cross-over and structure-complicated, large-scale underground cavern group excavation, certainly will cause adjustments of deformation fields and stress fields of surrounding rocks of underground cavern group,excessive large deformation and stress concentration will also fail surrounding rocks of underground cavern group, influence on cavern group stability. On the other hand, drilling and blasting are main construction method of the underground project excavation, it can't be ignored that the vibration response of surrounding rocks on dynamical loads. So, for a long time, it has been an important subject that the surrounding rocks stability evaluation of large-scale power station in geotechnical engineering.The works of this article include three parts as followed :Firstly, As view from the cavern group excavation causes surrouding rock stress redistribution influence stability of cavern group,this paper build numerical model by three-dimension fast Lagrangian moethod (FLAC^3D) ,the pattern of deformation caused by excavation and stress state in surrounding rocks of the chamber group under complex conditions are researched.The distribution of plastic areas and stability of surrounding rocks are analyzed. And the bolting is performed to support the vault of main power house, main substation,surge shaft.Secondly,considering it mainly make research by means of the two dimension FEM in the passing research in numerical simulation of the stability of surrounding rocks under blasting vibration loads ,and now the commercial FEM analysic software LS-DYNA3D can solve the three-dimension non-linear structure's dynamic questions,so by means of the software,this paper introduce three-dimension elastic-plastuc dynamic FEM to dynamic calculation of blasting and analyzes stablity of surrounding rocks under blasting vibration loads, calculate the laws of stress field,velocity field and displacement field of surrounding rocks on condition of various blasting method,various blastingpostion and near blasting.Finally, Stress wave vibration effect in near, the magnifying effect of velocity along the height of rock in the far field, result of calculation and survey datum comparision and analyse, parameter sensitivity that a series of great technological questions are analyzed. This paper results of combination numerical analysis, has discussed two kinds of safe problems in the cavern group excavation of underground engineering, offer reference for the practical project in the future.