盾构近距离穿越高架桩基的施工影响与保护措施

上海长江西路越江工程规模为双洞6车道盾构法隧道，采用外径为15.43 m的超大泥水盾构进行掘进施工。根据线路规划方案，该隧道需要近距离往返2次穿越逸仙路高架和地铁3号线高架桥墩桩基。盾构隧道的直径较大，并与高架桩基间的距离约为1 m，且不符合相关工程保护条例的要求，因此，有必要对盾构隧道近距离穿越高架桩基的施工影响和保护措施进行研究。借助有限元数值分析，模拟隧道近距离穿越高架桩基的施工过程，在考虑盾构施工引起地层损失的基础上，采用全方位高压喷射工法（MJS）加固桩基，并考虑不同的加固范围，分析施工对桩基变形和承载力的影响，提出一种安全经济的桩基保护措施。通过与实测数据对比，验证了提出的桩基保护方案的合理性。

Influences of construction of side-crossing shield tunnel on adjacent pile foundation and reinforcement effect of protection measures

The river-crossing project at Shanghai West Yangtze River Road is dual six-lane scale adopting large slurry shield of which the outer diameter is 15.43 m for the tunneling construction. Because the distance between the large diameter tunnel structures and pile-foundation is about 1 m, it is not in accordance with the relevant regulations related to the protection of engineering. So, it is necessary to study the influence of construction of side-crossing shield tunnel on adjacent pile foundation and the reinforcement effect of protection measures. In this paper, numerical simulation and field monitoring are employed to study the construction effect based on the ground loss, metro jet system(MJS) reinforcement of piles and different scopes of consolidation are taken into account. A safe and economical protect measure is presented by analyzing the deformation and bearing capacity of pile foundation. Finally, it is showt that the field monitoring data agree well with the numerical results. Therefore, the accuracy and rationality of the numerical simulation method is validated.