Abstract：The mode of pit-in-pit is becoming more and more common in foundation pit projects，however，it has not been systematically studied. Its uncertainty in position and shape，on one hand，raises the bar in design and construction，on the other hand，makes the surrounding strata deformation much more complicated. Based on the hypothesis of theoretical excavation line and function mass，the mechanism of difference in surrounding strata deformation was proposed. A prognoses method on curve and the maximum value of ground subsidence which is suitable for Beijing area was put forward combining the theory of ground loss with empirical equations. And on this basis，the reasonableness and adaptability of prognoses method by comparing with numerical simulation method and the empirical method were analyzed. Moreover，conclusion of ground settlement which is sensitive to excavation depth the most was also presented. The research findings can guide the design and construction of similar engineering in Beijing and other areas，and has a great significance in preventing engineering accidents and avoiding wasting resources，which can also be provided as reference material for precise control of impact made by pit-in-pit excavation on surrounding environment.
吴铭炳，林大丰，戴一鸣，等. 坑中坑基坑支护设计与监测[J]. 岩土工程学报，2006，28(增)：1 570-1 572.(WU Mingbing，LIN Dafeng，DAI Yiming，et al. Design and monitoring of retaining of pits in foundation-pit[J]. Chinese Journal of Geotechnical Engineering，2006，28(Supp.)：1 570-1 572.(in Chinese))
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2015, Vol. 34 
