EVALUATION OF INFLUENCE OF BLASTING WORKINGS ON THE STABILITY OF DOUBLE TUNNELS

Tuan Minh TRAN, Xuan Nam BUI, Quang Hieu TRAN, Quang Huy NGUYEN,
Vladimir Ivanovich GOLIK

T. M. Chan et al. / News of the Ural State Mining University. 2018. Issue 4(52), pp. 84-92

Relevance of the study is explained by the need to build a large amount of underground traffic arteries in the complex structural rock masses of Vietnam. The solution of the problem can serve as a basis for optimizing the processes of construction of underground multipurpose facilities.
Purpose of the study is to determine regularities between technological stresses due to blasting workings in a new tunnel and keeping of construction and rocks in the existing tunnel to optimize the parameters of the tunnel poling boards.
The most important task of the study is to obtain quantitative parameters of stress of the rock mass by simulating the conditions of a tunnel under specified conditions using the finite element method and taking into account that the explosion pressure during expansion of the auxiliary tunnel before the design section is fixed on the contour of the designed tunnel. The subject of the research is the Hai Van transport tunnel in the North-South Vietnam road.
Results and discussion. The methodology and results of numerical modeling using the Phase 2 program for the conditions of construction of the main and auxiliary tunnels are given. The parameters of the distribution of stresses and strains in the vicinity of the auxiliary and main tunnels with varying explosive pressure are obtained. The quantitative values of safe explosive pressure for poling boards in the elements of the system of both tunnels were obtained. The safety parameters of blasting workings are recommended (according to the stability factor of poling boards).
Conclusions. Technogenic stresses generated by blasting workings in the rock mass that encloses building sites do not destroy the poling boards of a tunnel, if they do not exceed the value specified for these conditions; they are technologically regulated by choosing rational blasting parameters at any stage of construction.

Keywords: blasting workings, blast wave, pressure, poling board, tunnel, stress, stability.

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