近临磁浮线基坑抽灌一体化技术的试验研究

Experimental Study on Pumping-Filling Integrated Technology of Foundation Pit near Maglev Line

目前,抽灌一体化设计在基坑降水领域的应用仍属于探索阶段。以上海市首条市域铁路浦东机场站深基坑工程为例,其紧临上海磁浮线,桩基沉降需控制在2 mm以内,为减小基坑降水引起的坑外重点保护建筑的沉降,基于沉降控制的回灌技术运用于该基坑工程中。现场试验监测资料表明,采用坑外回灌效果明显;常压下,单井回灌量约为单井出水量的1/3;对于悬挂式止水帷幕,绕流作用明显,水位下降幅度可达50%以上,但超过一定深度后,绕流效果出现拐点,抽灌一体化可应用于控制降水引起的沉降。

At present,the application of pumping-filling integrated technology is still exploratory in the dewatering filed of foundation pit.Taking a deep foundation pit project of Pudong Airport Station in the first municipal railway of Shanghai near Shanghai Maglev Line as an example,the settlement of pile foundation is required to control within 2 mm.In order to decrease the settlement of the key protected buildings outside the pit caused by the dewatering of foundation pit,the refilling technology based on the settlement control is applied in this project of foundation pit.The on-site experimental monitoring data show that the refilling effect outside pit is obvious.The refilling quantity of single shaft is about 1/3 of water discharge of single shaft under the constant pressure.For the suspension type of waterproof curtain,the streaming role is obvious.The drop range of water level can be more than 50%.But beyond a certain depth,the streaming effect has an inflection point.The pumping-filling integration can be used to control the settlement caused by the dewatering.