Numerical Simulation Analysis On Influence Of Blasting Excavation In Main Underground Powerhouse To Adjacent Cavities

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. On the other hand, drilling and blasting are main construction method of the underground project excavation, it can make 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 paper use the finite element method (FEM) and the software of ANSYS/LS-DYNA simulate the construction of the large-scale underground cavern group. All of the works of this article include three parts as followed:(1) The paper summarized the present study of influence of nearby blasting on a underground powerhouse system, and also point out the different between the old method and the latest method.(2) The paper explained how to use the FEM in works , and especially discussed dynamical FEM and nonlinear problems. The paper also emphasized how to define the element type and meshing, which is very important for blasting simulation.(3) Through perusing many article about this field, the paper introduced the theory of destroying of the rock and the stress wave which caused by the blasting systemically. The paper also expatiated the calculating method of the blasting resistance, and give some of my own opinion on how to use the LS-DYNA to simulate vibration caused by blasting.(4) In view of the difference of pre-splitting blasting and smooth wall blasting influence to the circumjacent chamber excavation, the paper simulated the drilling and blasting of the underground powerhouse. Of all the character of the influence , the vibration speed is the most important thing. The paper discussed the blasting vibration speed of the main transform house and the tailrace gate strobe which caused by pre-splitting blasting and smooth wall blasting.(5) Except the effects of vibration to the underground powerhouse system, the excavating of the main underground powerhouse also can cause instability to the system, so the paper calculate the stress of all the system after the excavating of every layer.(6) The paper contrast the result of the calculation of the LS-DYNA and the data of the vibration speed which is survey at the locale and try to find whether the result of the simulation is accord with the reality. Through the calculation of the LS-DYNA, the computer can get a discipline of attenuation of the blasting vibration speed, and so do the survey at the locale. The paper analyse the why the disciplines which get from different ways are distinct and what caused this phenomenon.