Centrifuge shaking table tests on overflow-based pressure control system for seismic response and uplift control of underground structures

Under strong seismic excitation, excess pore water pressure (EPWP) within liquefiable soil layers rises rapidly, reducing soil effective stress and increasing buoyant uplift forces on underground structures, which may lead to structural damage. Engineering disaster records over recent decades concerning underground structure uplift induced by soil liquefaction indicate that conventional hydrostatic-based anti-uplift design approaches may become inadequate under seismic liquefaction conditions. This paper proposes an overflow-based pressure control (OPC) system. By installing automatic overflow valves on the base slab of underground structures, the accumulated EPWP beneath the slab during earthquakes are controllably released along a preset path, so as to alleviate seismic response to underground structures. Two comparative centrifuge shaking table tests (with and without OPC system) are conducted. Test results indicate that the OPC system significantly reduces the EPWP beneath the base slab of the underground structure, attenuates its seismic acceleration responses, and mitigates structural uplift. The findings of this study provide a novel technical framework and reliable experimental evidence for methods to reduce seismic responses and achieve uplift control of underground structures constructed on liquefiable sites subjected to seismic loading.