岩壁梁部位开挖施工关键技术研究

岩壁梁是桥式起重机运行时的受力结构,是地下厂房系统开挖的重点和最难点。针对瀑布沟水电站特大型地下厂房地应力高、岩体地质构造节理发育、工期紧迫及岩壁梁部位开挖质量要求高等特点,中部拉槽首次采用了“三步起爆一次开挖施工光面—预裂爆破”新技术,在岩壁梁岩台以上保护层部位采用“直孔和斜孔光面爆破一次开挖”方法,减少了爆破对岩壁的扰动,确保了岩壁开挖成型质量,创造了炮孔痕率100%、由爆破和围岩卸荷造成的影响深度在0.2⁰.8m、岩壁平均超挖8.7cm的新记录,开挖质量优良。

RESEARCH ON KEY TECHNIQUE OF ROCK ANCHOR BEAM EXCAVATION

Rock anchor beam,the sustentation structure of the bridge-type lift,is the emphases and difficulty in excavation of underground powerhouse.The underground powerhouse of Pubugou power-station was located in a high geo-stress area,which is characterized by complicated rock cracks and joints.Because of the high requirement of construction quality of rock anchor beam excavation and strict time limit for the project,some new blasting techniques were adopted.The'Controlled Blasting with Three-stage Ignition'was first used in central cutting excavation,and the'Vertical-slope Hole Controlled Blasting'was used in upside protective layer excavating of rock anchor beam.These new technologies reduced the blasting vibration and insured the construction quality of rock anchor beam excavation,creating the new records of blasting excavation in terms of 100% of leftover ratio of bore holes,0.2～0.8m of influencing depth caused by blasting and excavating,and only 8.7cm of the average rock face unevenness.