For the safety and serviceability of an existing underground structure due to a new excavation below, a soil-structure separation model based on subgrade reaction analysis is proposed to study the responses of the existing underground structure. Our proposed method can determine the soil gap formation and then predict the soil gap dimension. Our method's length and height of the soil gap agree well with the data from two centrifuge tests. Parametric analyses are conducted in this paper to investigate the effects of the main influence factors on soil gap formation. A modified stiffness ratio, named soil gap coefficient C_g, is provided to determine the soil gap formation as a tool for preliminary assessment. The soil gap coefficient C_g is suitable for different soil types (different Young's moduli). This paper indicates that the soil gap is potentially formed beneath the existing underground structure when the soil gap coefficient C_g is less than 300.

针对地下新开挖引起的既有地下结构的安全性和可使用性，提出了一种基于路基反应分析的土-结构分离模型来研究既有地下结构的响应。我们提出的方法可以确定土壤间隙的形成，然后预测土壤间隙尺寸。我们的方法的土壤间隙的长度和高度与来自两次离心机测试的数据非常吻合。本文通过参数分析研究了主要影响因素对土壤间隙形成的影响。提供了一个修正的刚度比，称为土壤间隙系数C _g，用于确定土壤间隙的形成，作为初步评估的工具。土隙系数C _g适用于不同的土壤类型（不同的杨氏模量）。本文表明土壤间隙可能形成现有的地下结构下方当土壤间隙系数Ç_克小于300。