三峡二期工程基岩保护层开挖方法研究

Excavation method for protection layer of foundation rock at TGP

三峡二期工程建筑物基础开挖面积约２３．６７万ｍ２，其中主体建筑物基础面积约为１４．４万ｍ２，基础岩石开挖强度高，清基交面最高月强度超过４万ｍ２，若按过去“层层剥皮”开挖方式是难以完成的。保护层采用“一次爆除法”是改进基础开挖工艺，加快清基交面速度，降低保护层开挖费用的好办法。对实施“一次爆除法”进行保护层开挖的参数选择、削减爆孔底部破坏的技术措施、基础质量评价等方面提出了具体建议和标准。

The excavation area for the foundation of TGP second stage structures is about 236 700 m 2, of which the foundation area of the main structures is about 144 000 m 2. Due to a high intensity of excavating foundation rock, with the monthly intensity of cleaning and handing over foundation rock face exceeding 40 000 m 2, it is difficult to complete excavation works in time in a way of “explosive stripping one layer after another”. Adopting “one time explosive stripping method” for excavation of protection layer is a better way to improve the foundation excavating technique, speed up the cleaning and handing over of foundation rock face and lower the excavation cost of protection layer. Some concrete proposals and standards related to selection of parameters, technical measures for mitigating the damage to the bottom of explosive holes, assessment of foundation quality for implementation of the one time explosive stripping of protection layer are put forward.