The Hole Quality Control And Influence Research On Small Section Hydraulic Tunnel

Diversion tunnels are always small shallow section tunnels. In view of poorlithology rock mass, the hole quality is always hard to control. It is of greatsignificance to do research on the hole quality’s key factors and how to control thesefactors.This paper uses theoretical analysis, model test, excavation experiments tocarry out rock stability influence analysis, weak blasting disturbance research andhole forming qualities under different conditions. And put forward a weakdisturbance blasting control technology framework based on weak disturbance’scomposite charge structure. The main research results are as follows:(1) Through tunnel hole quality influence factors analysis, reasonable tunnelblasting excavation is the key technology of small section tunnel construction. Goodquality can improve surrounding rock, keep surrounding rock stability and radius ofplastic zone. Tunnel support parameters especially primary support parameters shouldbe fully combined with the buried depth. Strengthen supporting surround rockparameters can control plastic zone.(2) Based on propagation of blast wave have directions and blasting test, theresearch put forward a weak perturbation composite charge structure. Finally, itverifies that the detonation wave propagation direction have influence on the blastingdirection. Its apparent unilateral effect shows weak perturbation composite chargestructure’s improvement is more advantage to reduce surrounding rock disturbance.(3) Field application and contrast test show that, in poor lithology rock, weakdisturbance charge blasting technology can also achieve ideal smooth blasting result.Compared with ordinary blasting, the rock surface is smoother. It is a recommendedcontrolled blasting technology for excavation a tunnel.(4) Through establish small section tunnel finite element model, comparativeanalysis tunnel lining structure and surrounding rock mechanics characters. Finally, itimproves that the weak perturbation charge control blasting excavation can form goodhole quality. At the same time, improve the surrounding rock disturbance parameterscan control some related parameters. Due to some improper blasting excavations canlead to landslide or collapse, when the small section hydraulic tunnel going through mountain valley or shallow overburden. It is necessary to strengthen support when thetunnel going through these places.