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摘要: 针对地应力条件下的溪洛渡水电站右岸大跨度导流洞的开挖,依托现场的爆破实验参数,结合LS-DYNA软件,进行了隧洞岩体爆破开挖过程围岩的动态响应计算。分别采用峰值质点振动速度和最大拉应力安全判据确定围岩的爆破损伤范围。计算结果表明,隧洞爆破开挖时,最大峰值质点振速和最大拉应力均出现在洞室边墙中部,因此,爆破损伤在洞室边墙部位最严重。通过对洞室边墙中部的峰值振速和最大拉应力的数值拟合,得到了峰值质点振速和最大拉应力的统计关系,并进行了相关性检验,而且根据所得统计关系,结合实际工程围岩动态抗拉强度准则,提出了控制隧洞围岩爆破损伤的临界峰值质点振动速度。Abstract: Based on the field testing of the blasting vibration on a large-span project of the underground diversion tunnel in Xiluodu, which locates in the southwest of China, with middle geostress, the dynamic responses of the surrounding rock during the blasting excavation were calculated by combining LS-DYNA.The peak particle vibration velocity and the maximum tensile stress were used as the safety criterions to confirm the range of blasting damage, respectively.The calculation results indicates that the peak particle vibration velocity and the maximum tensile stress both appear in the middle of the sidewall in the blasting process, therefore the most dangerous area in the blasting process lies in the middle of the sidewall.The statistical relationship between the peak particle vibrating velocity and the maximum tensile stress in the middle of the sidewall was obtained by the numerical matching method, and the correlation coefficient of the peak particle vibrating velocity and the maximum tensile stress was tested.According to the statistical relationship between the stress and the vibrating velocity, the critical peak particle vibration velocity was put forward for controlling the damage to underground tunnel rock.
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表 1 洞室轮廓危险部位最大应力
Table 1. Maximum stresses in dangerous area of underground diversion tunnel
测点 动载单独作用 动静载共同作用 σ1/MPa τ/MPa σ1/MPa τ/MPa 1 1.54 0.76 -0.44 11.29 2 8.06 4.13 -2.78 10.43 3 16.35 13.40 8.83 14.20 4 6.87 7.63 6.37 11.08 5 10.05 12.00 -6.10 12.85 6 19.93 14.60 4.83 14.46 表 2 不同初始地应力条件下的围岩损伤临界振速
Table 2. The critical value of peak particle vibration velocity for damage under different geostresses
σcru/MPa β=1.00 β=1.67 vc, p/(cm·s-1) vc, h/(cm·s-1) vc, p/(cm·s-1) vc, h/(cm·s-1) 0 10.46~21.35 32.42~ 43.60 10.46~21.35 32.42~ 43.60 10 29.31~61.97 83.83~101.64 40.68~74.15 97.55~116.77 20 20.35~51.21 78.35~ 97.59 21.40~58.85 84.44~103.52 30 10.81~31.79 60.06~ 73.97 15.86~42.70 64.78~ 78.65 -
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