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依托于南京地铁一号线南延线百家湖车站工程,利用经验证的数值模型和计算方法,研究了支护桩入土深度、不同型钢型号、型钢布置形式、不同支撑轴力、不同支撑水平间距等参数对SMW围护结构变形的影响。得出了各因素对围护结构变形的影响规律:支护结构的入土深度过小,会造成“踢脚”现象,在保证基底不失稳的条件下,当入土深度超过1.5H后,继续增加入土深度对减小支护结构水平位移的效果很小;不同形式的内插型钢布置对支护结构变形影响较大,型钢的型号对基坑变形影响较小;增加各道支撑预加轴力可以有效的减小围护结构变形,但施加过大的预应力会导致支护桩的过分后移,影响支护桩的强度,建议按照设计轴力的50%~80%取值;减小支撑水平间距是减小位移的有效方法,本车站工程支撑水平间距设为3.5~4 m为宜。
Relying on the project of Baijiahu Station on the South Extension Line of Nanjing Metro Line 1, using the validated numerical model and calculation method, the effects of depth of support pile, different type of steel, arrangement of section steel, different supported axial forces, different support levels Influence of Spacing and Other Parameters on the Deformation of SMW Envelope. The influence of various factors on the deformation of the envelope is obtained. If the penetration depth of the supporting structure is too small, the phenomenon of “kick-in” will be caused. Under the condition of not losing the stability of the substrate, when the depth of penetration exceeds 1.5H , The effect of increasing the depth of soil penetration on reducing the horizontal displacement of supporting structure is very small. The impact of different forms of inserted profiled steel structure on the deformation of supporting structure is larger, and the shape of profiled steel has less influence on the deformation of foundation pit. Addition of axial force can effectively reduce the deformation of the retaining structure, however, excessive prestressing will lead to excessive displacement of the retaining pile and affect the strength of the retaining pile. It is suggested that 50% ~ 80% of the designed axial force should be used ; To reduce the level of support is an effective way to reduce the displacement of the station engineering support horizontal spacing is set to 3.5 ~ 4 m is appropriate.