In order to study the variation of soil stress during the jacking of under-crossing box culverts

the dredging and widening project of Dingxi River Railway Bridge located on Xinchang Railway is taken as an example. The variation of soil stress at the bridge abutment was recorded in real time during the whole process of the box culvert jacking. A three-dimensional finite element model of the box culvert and soil was then established based on ABAQUS. The normal contact and tangential contact between the box culvert bottom

the side wall and the soil were defined. Thus

the construction process of the actual box culvert jacking was equivalent to the nonlinear contact analysis of the box culvert with an initial displacement. According to the change of soil cutting height in actual construction

the condition of box culvert jacking with soil cutting heights of 4. 51 m and 6. 51 m was simulated respectively. Results show that the lateral earth pressures based on numerical simulation were generally larger than the measured values. The main reason is that the contact stress was adopted during the numerical simulation

whereas the side wall of the box culvert and the soil could be separated during the jacking process. When the soil height was 6. 51 m

the calculated frictional resistance of box culvert was very close to the recorded jacking force

and an approximate equilibrium was realized. However

when the soil height was 4. 51 m

the calculated frictional resistance was less than the actual jacking force.Conclusions show that it is reasonable to investigate the box culvert jacking based on the finite element method and real-time monitoring technology.