基于Hoek-Brown准则的爆破损伤对边坡稳定性的影响

Influence of Blasting Damage Zone on Slope Stability based on Hoek-brown Criterion

爆破是目前岩质边坡的主要开挖方式,为评估爆破损伤对工程边坡稳定性的影响,基于Hoek-Brown强度准则中的扰动因子D探讨爆破损伤的弱化规律。以岩体纵波波速变化表征D的空间变化规律,获得指数型分布的D值变化形式来反映爆破损伤程度的空间分布特征。探讨了D值的分布规律及爆破影响范围对边坡安全系数的影响。算例表明:D值按指数型分布规律渐变,稳定性系数为1.14;按线性和二次函数分布规律渐变时,稳定性系数增加至1.39和1.47;考虑扰动区范围内D值指数型分布渐变,采用系统锚杆加固能有效补偿爆破损伤造成的岩体力学性质下降及边坡稳定性不足。研究结果表明:采用D渐变弱化的方式,能较好的反映爆破损伤对边坡稳定的实际影响;采用系统锚杆可对爆破损伤进行有效控制;D的分布形式及范围会对边坡稳定性评价结果造成较大影响。

Blasting is the main excavation method of rock slope at present.In order to evaluate the effect of blasting damage on the stability of engineering slope,the weakening law of blasting damage is discussed based on the disturbance factor D in Hoek Brown strength criterion.Using the spatial variation of D characterized by change of longitudinal wave velocity in rock mass,the exponential type of D was obtained to reflect the spatial distribution of blasting damage degree.The impact on the factor of safety of the distribution rules as well as the influence area of the disturbance factor D were explored consequently.For the case in hand,the computed factor of safety is 1.14 when the value of D is gradually changed according to the law of exponential distribution,and the factor of safety increases to 1.39 and 1.47 respectively when it is gradually changed according to the law of linear and quadratic distribution.Considering the gradual change of exponential distributed D value in the blasting damage zone,the systematic bolts can effectively compensate the loss of the slope stability due to the rock mass mechanical properties weakened by blasting.The results show that considering gradual weakening of D can better reflect the actual effect of blasting damage on slope stability,the blasting damage can be effectively controlled by the system bolt,and the different distribution patterns and ranges of D have great influence on the factor of safety.