Study On The Control Techniques Of Rockburst On The Overlong And Deep-Buried Tunnel Of Water Diversion Project From The Han River To The Wei River

In this paper,we have studied the characteristics, laws, mechanism and influencing factors of rockburst on QinLing tunnel of the water diversion project from the Han river to the Wei river,by the method of engineering analogy, theoretical analysis and numerical simulation,based on the geological data, project information, test results of this tunnel and related documents. Specific control measures of rockburst for this project have also been proposed based on the analysis of various types of control measures. The main research works are as following:(1) According to the analysis of the characteristics of ground stress field, the direction of the horizontal tectonic stress,which is the maximum principal stress and is up to 50-60MPa, intersects with the tunnel alignment by a large angle.(2) According to the analysis of the characteristics and laws of rockburst,simulating the secondary stress distribution after the tunnel excavation by the method of numerical simulation,and the predecessors’research works, the mechanism of rockburst has been summarized.(3) The basic conditions of rockburst has been summarized for the rock conditions, to stress conditions and human conditions,which are indispensable.The influencing factors of rockburst such as the lithology, geological structure, structural surface, groundwater, cross-sectional shape of tunnel, affect the intensity levels of rockburst by affecting the the basic conditions of rockburst.(4) Integrated control measures should be taken to prevent rock burst,but not a single one. Using drill and blast construction method, the method of full section excavation should be taken,follow the principle of "short footage, weak burst", control the blasting parameters to improve effect of smooth blasting, using the method of pre-splitting blasting if necessary.