Revealing the dominant influence of joints: Soil-structure-component-joint adaptivity for prefabricated underground structures

Compared to the traditional cast-in-situ technique, the novel prefabricated underground structure (PUS) employs machinery excavation and assembly. Notably, the PUS assembly system undergoes multi-level force transmission through soil, structure, component, and joint interactions. This transmission mechanism remains inadequately understood, consequently posing frequent instability risks during PUS construction. Hereby, this study foremost addresses this problem for multi-level information modeling and planning for PUS under joint principal control. Three modules of numerical modeling, design theory and adaptive planning were constructed and integrated into the Soil-structure-component-joint Adaptive Planning Model (SAPM). Through a real-project application of SAPM, key insights are as follows: (1) SAPM achieves multi-level information adaptivity by planning the joint properties, which mitigates the soil-structure interaction effect of main and secondary structures by 18% and 63%, respectively. (2) Different joints and components may not achieve optimum solutions with uniform joint properties. Top, bottom and midslab joints achieve multi-level information adaptivity only when their respective joint stiffness factors are 0.90, 0.61 and 0.65. (3) The use of semi-rigid joints in PUS has multiple advantages over the common cast-in-situ rigid joints. The semi-rigid scheme reduces ring assembly time and cost by approximately 40% and 20%, respectively, compared to hinged and rigid joint schemes. The research results provide a theoretical and instrumental basis for the safe construction of PUS in complex urban and geotechnical environments. • PUS assembly system undergoes multi-level force transmission • Soil-structure-component-joint Adaptive Planning Model was built for PUS planning • SAPM deeply mines joint property for multi-level information adaptivity • Semi-rigid joints achieve precise and economical planning of multi-level information • Semi-rigid joints in PUS has multiple advantages over the cast-in-situ rigid joints