Analysis of deformation patterns of bridge construction support under insufficient foundation bearing capacity

MA Wenlong; WU Guohua; DONG Shujing; ZHAN Yuhua; ZHAO Yulong

doi:10.3969/j.issn.1672-0032.2025.03.004

Abstract：To predict the stability conditions of the support structure and achieve effective early warning,finite element software MIDAS CIVIL is used to model the pin-supported disc-type supports of the bridge,simulating the response characteristics of the support structure under single-point settlement and regional settlement conditions.Using in-situ testing methods on the bridge,a comparative analysis is conducted between the simulated data and the actual measurement data of the support deformation,demonstrating the feasibility of using angular change thresholds to monitor the preloading and pouring processes,and acquiring the deformation patterns at critical positions of the supports.The results show that the deformation data measured by the gyroscope closely match the simulated data,and the angular change threshold for construction process monitoring is feasible.Insufficient foundation bearing capacity leads to three different settlement conditions:first,when the single-point foundation bearing capacity is insufficient,forced displacements are applied to the four corner support rods at the bottom plane of the middle part of the support structure,resulting in significant angular changes at four measurement points,but none exceeds the warning threshold;settlement occurred at the position where the largest reaction force from the support is applied at the bottom of the support;second,when the foundation bearing capacity is insufficient in certain areas,forced displacements are applied to the middle,left,and right parts of the support structure,significantly affecting the key monitoring sections,with noticeable changes in local structural displacements;the angular changes remain within the permissible thresholds,and the reduction rates of displacement and angle during the pouring condition show minimal variation;third,when the foundation bearing capacity at the bottom of the members where each measurement point is located is insufficient,simultaneous node displacements are applied to the bottom nodes of the monitoring sections,with major settlement occurring in the regions around the bottom of the measurement points;the angular threshold increases with the increase in load,validating the effectiveness of the settlement identification and early warning method based on angular thresholds.