新型钻机在“PBA”洞桩法中的应用

Application of New Drilling Rig in"PBA"Cave Pile Method

研究发现冲击钻施工震动大,反循环钻在卵石层适用性差,旋挖钻外型尺寸大,该类问题一直困扰北京地铁采用PBA工法的暗挖车站施工。传统解决方式是开挖上下双层导洞,但该方式有许多不足,当地下水位高时,下层导洞的开挖支护与沉降难以控制;底纵梁较窄,在软弱地层,难以保证承载力;逆作开挖落底时,侧壁桩会出现水平位移,需增加横通道和横梁;降水周期长,水资源浪费严重;人工挖孔安全性差。因此急需一种适应卵砾等复杂地层、外型尺寸小的钻机。本文借助北京地铁16号线二里沟站机械成孔的成功案例,介绍一种新型反循环钻机应用,并为类似工程建设提供经验。

The research found that the impact drilling construction has large vibration,the poor applicability of reverse circulation drilling in the pebble layer,and the large size of the rotary drilling drill.These problems have been plagued by the Beijing Metro's underground excavation station construction using the PBA method.The traditional solution is to excavate the upper and lower double-layer guide tunnels,but this method has many disadvantages.When the groundwater level is high,the support and settlement of the lower guide tunnels are difficult to control.Carrying capacity;when the bottom excavation is reversed,the lateral piles will be displaced horizontally,and the horizontal passage and beams need to be increased;the rainfall period is long,and water resources are seriously wasted;Therefore,there is an urgent need for a drilling rig that adapts to complex formations such as gravel and has a small size.Based on the successful case of mechanical hole formation in Erligou Station of Beijing Metro Line 16,this paper introduces the application of a new type of reverse circulation drilling rig and provides experience for similar projects.