防止盾构侧穿桩基时引发桩基沉降的措施

New Technology of Preventing Settlement of Pile Foundation Induced by Tunnel Construction

盾构施工从桩基侧面穿过时,由于推进过程中对地层挤压以及隧道从盾尾脱出时地层损失的作用,会使得土体产生沉降和侧向位移,继而造成既有桩基的变形,这是隧道工程中的难点问题。传统的注浆加固措施,较难适用于地下水丰富的软土地区,并且加固过程中消耗大量材料、加固后质量控制的可靠性不高。为克服上述传统施工措施不足,在原有桩基底部设置扩底装置来增大桩端承载能力,减小隧道侧穿桩基时引发的桩基沉降。现场施工结果表明,上述施工措施不受地下水含量的限制,施工过程的经济性、可靠度均较好。

Shield construction, nearing piles foundation, may disturb the surrounding soil, which can lead to the deformation of the soil that would cause the settlement of piles foundation nearby, which is a difficult problem in tunnel engineering. Traditionally, we may resort to grouting technique to reinforce the soil and pile foundation. However it may not be proper to use grouting technique in the condition that the water in the soil is considerable. Besides, the process of the grouting technique is complex, with poor efficiency. Based on a case study, this paper proposes a new technique, whose efficiency has been certified by engineering practice and which is not influenced by saturate soil, to prevent the settlement of pile foundation induced by the shield construction.