坚硬地层旋挖施工小直径砂桩近距离隔振应用

APPLICATION OF SHORT-DISTANCE VIBRATION ISOLATION OF SMALL-DIAMETER SAND PILE IN ROTARY DRILLING CONSTRUCTION IN HARD STRATUM

坚硬地层旋挖钻机成孔施工振动较为强烈,易对周围地下结构造成不利的影响,尤其是当旋挖成孔距离受保护地下结构较近时,隔振需求愈发强烈。利用济南地铁燕山立交桥东站基坑支护工程,通过现场试验、数值模拟与工程监测等方法,研究了旋挖施工小直径砂桩近距离隔振效果。结果表明:旋挖振动产生的竖向加速度高于水平方向,而竖向加速度衰减速率更大;采用小直径砂桩隔振后不同深度加速度削弱幅度为38%~65%;旋挖施工引起的邻近地下管沟侧壁影响明显,且竖向振动速度为横向的4.6~5.1倍,采用小直径砂桩隔振可使地下结构振动速度减小40%以上。由此可见,小直径砂桩隔振有效降低了旋挖成孔振动对近距离地下管沟的影响。

The violent vibration of rotary drilling rigs in drilling of hard strata has adverse effects on surrounding underground structures.In particular,more vibration isolation is required for rotary drilling close to the underground structures to be protected.Taking the foundation pit support project of the Yanshan Lijiaoqiaodong Metro Station in Jinan as an example,the short-distance vibration isolation effects of small-diameter sand piles in rotary drilling were studied by field testing,numerical simulation,engineering monitoring,etc.Results showed:The vertical acceleration of vibration in rotary drilling is greater than the horizontal acceleration but decreases at a larger rate.Through vibration isolation of small-diameter sand piles,the acceleration decreased by 38%to 65%at different depths.Rotary drilling has significant impact on the side walls of adjacent underground pipe trenches.The vertical vibration velocity was 4.6~5.1 times the transverse vibration velocity.The vibration velocity decreased by more than 40%if underground structures are subject to vibration isolation by small-diameter sand piles.Accordingly,the vibration isolation of small-diameter sand piles effectively reduces the influence of vibration on nearby underground pipe trenches in rotary drilling.