关键词: 隧道工程；爆破荷载；楔形体；稳定性分析；加速度

Abstract: The analysis of the stability of the tunnel wedge rock is the basis for the prevention and control of the tunnel rock disaster. Based on the blast peak acceleration attenuation law and the assumption of the wedge structure surface, the peak blasting load acting on the wedge was determined by Newtons second law, and the time-lapse blast inertia force was obtained by modifying it. The physical model and calculation model of tunnel wedge-shaped dangerous rock stability analysis were established. And the dynamic limit equilibrium method of wedge-shaped stability analysis was proposed, by which the formula for calculating the stability coefficient of wedge was obtained. Furthermore, the influence of different factors on the stability coefficient was analyzed. The calculation results show that: under the blasting load of the side wall wedge, the wedge-shaped body changes in pressure and tension with time, and the whole action time lasts about 0.3~0.4 s. Under the blasting load, the maximum peak load of the side wall wedge is 410.52 kN, and the minimum peak load is -285.69 kN. Under the blasting load, the maximum peak load of the wedge on the top of the tunnel is 140kn, and the minimum peak load is -95.23kn. The stability coefficient of side wall under single sliding surface blasting load increases by 93% in max and decreases by 63.3% in max, and the stability coefficient of double sliding surface of side wall increases by 75% in max and decreases by 47.4% in max. Under the blasting load, the stability coefficient of the single sliding surface on the top of the tunnel increases by 75.5% in max and decreases by 56.4% in max, and the double sliding surface at the top of the tunnel increases by 81.5% in max and decreases by 57.8% in max. When the explosion center distance is increased from 2 m to 5 m, the maximum difference between the two stability coefficients is 1.92. When the inclination angle of the sliding surface is increased from 28° to 58°, the natural stability coefficient is reduced by 1.5, and the impact of blasting on the stability coefficient is reduced by 4.5 in max. When the amount of explosives is increased from 28 kg to 58kg, the stability coefficient is increased by 1.65 in max. When the area is increased from 8 m2 to 20 m2, the stability coefficient is increased by 0.75 in max. Therefore, the proposed calculation method of wedge stability coefficient can better reflect and evaluate the stability of tunnel wedge under blasting load.

Key words: tunnel engineering; blasting load; wedge; stability analysis; acceleration