Study on soil gap formation beneath existing underground structures due to new excavation below

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.