Response analysis of double-cabin comprehensive utility tunnel under traffic dynamic load effects

WANG Shengli; FU Shengxiang; HU Peng; CHI Lianyang; TU Xiongwei; YANG Shenpeng; GONG Yuhao

doi:10.3969/j.issn.1672-0032.2025.05.005

Abstract：To investigate the effects of vehicle dynamic loads on the settlement and mechanical performance of the underground comprehensive utility tunnel in silty soil foundations,a calculation model of the buried comprehensive utility tunnel is established using the finite element software PLAXIS 3D,and a scaled model test is conducted to verify the reliability of the numerical model.By applying a sinusoidal wave to simulate vehicle dynamic loads,the influences of parameters such as tunnel burial depth,elastic modulus of backfill soil,groundwater level,vehicle load amplitude and loading position on the settlement and dynamic response of the tunnel are analyzed.The results show that:1)The settlement at each measurement point significantly increases within the first second,followed by periodic oscillation and stabilization,with the settlement of the soil at the bottom of the tunnel being less than that without the tunnel.2)The tensile stress in the tunnel is mainly concentrated on the inner side of the top slab of the left chamber,the upper outer side and the middle inner side of the left side wall,and the middle inner side of the right side wall,with the maximum tensile stress peak occurring on the upper outer side of the left side wall and the largest fluctuation amplitude generated on the inner side of the top slab of the left chamber.3)The vibration acceleration response of the top slab is larger,as it transmits the vibration acceleration response along the tunnel side walls and the central diaphragm to the bottom slab,with the top slab and side walls stabilizing around the second second,and the bottom slab stabilizing around the first second;after stabilization,the peak vibration acceleration of the top slab is the largest,while that of the bottom slab is the smallest.4)As the burial depth of the tunnel increases,the settlement of the soil at the bottom of the tunnel decreases,and the peak vibration acceleration of the top slab,side walls,and bottom slab decreases,with a recommended burial depth of 2.5 m to 3.0 m;as the vehicle load amplitude increases,the peak tensile stress,settlement,and peak acceleration of the tunnel all increase;the vehicle load applied directly above the comprehensive utility tunnel is the most detrimental to the tunnel,resulting in the maximum peak tensile stress and acceleration,while moving the loading position away from the tunnel's central axis to the left or right generally reduces the peak tensile stress and vibration acceleration of each structure of the tunnel.5)An increase in the elastic modulus of the backfill soil helps to reduce the settlement and peak acceleration of the tunnel.With the increase of groundwater level,the settlement at the bottom of the tunnel initially decreases slightly and then increases.