Study on the Vibration Influence Law of Bored Cast-in-place Pile Construction on Existing Strata and Pipe Trenches

Abstract

［Objective］ The rotary drilling process of bored cast-in-place piles will cause vibration to the existing underground buildings and structures. Therefore, it is necessary to study the vibration response of the strata and structures caused by the rotary drilling process. ［Method］ Taking a station foundation pit excavation project of Jinan Metro Line 4 as the background, through field tests and numerical simulation methods based on three-dimensional finite element models, the influence of soil layers and power pipe trenches vibration caused by rotary drilling construction is analyzed considering factors such as vibration source distance, burial depth, excavation depth, different power pipe trench positions, and the number of piles under simultaneous construction. ［Result & Conclusion］ The closer the soil and existing power pipe trench are to the vibration source, the greater the vibration effect they receive. The vibration effect on the soil and existing power pipe trenches can be ignored when the distance from the vibration source exceeds 6 m. The vibration effect on the soil shows a decreasing trend with the increase of burial depth. After the excavation depth reaches 12 m, the vibration impact on the shallow buried power pipe trench can be ignored. When the measuring point and the vibration source are at the same depth, the vibration impact at the measuring point is the greatest. With the decrease of the clearance between the two simultaneously-constructed piles, the vibration velocity peak value shows an increasing trend. When the net distance between two simultaneously-constructed piles is 10 m, the vibration coupling effect can be ignored.

Keywords

• subway
• foundation pit
• bored cast-in-place pile
• rotary drilling construction
• vibration impact