Abstract: The Soil improvement in the passive resistance zone of deep excavations can improve the embedded conditions of the supporting structures in the passive area, strengthen the control of the horizontal displacement of the support structure as well as the subsidence of the surface soil after the excavation, which is a common reinforcement measure for the deep excavations in thick, soft soils. The soil improvement design in the passive resistance zone of a deep excavation in the thick and soft soil area in Jingzhou City is presented in this paper. The commercial finite element analysis software of geotechnical engineering is used to analyze the improvement effect of the passive resistance zone under different improvement sizes. The results show that using the maximum displacement of the soldier pile as the control indicator, the width and the depth of the rectangular improvement of the soil in the passive resistance zone have the optimal design range values. When the improvement width and depth are not in the optimal design range values, the required improvement volume increases significantly, which can play a valuable reference for the design of the improvement of the passive resistance zone of the deep excavations in soft soils.

Key words: Deep Excavations, Passive Resistance Soil Zone, Thick Soft Soils, Size Rectangular Improvement Zone, Design Optimization