Evolution of the deformation characteristics of an inclined over-deep caisson based on the dynamic control method of uneven settlement

Abstract

Taking a caisson foundation engineering of a railway across-river bridge as the case, the technical characteristics and key challenges of over-deep inclined caisson were described firstly. Subsequently, the main controlling factors of the uneven settlement were analyzed. In view of the difficulty in obtaining the parameters of disturbed grouting soil, as well as the large adjustment of subsequent construction loads, an uneven settlement method based on over-deep underwater lateral pressure test and high-pressure consolidation test was proposed. The proposed method was simulated by finite element method to analyze the variations of total settlement, differential settlement and inclined attitude of caisson foundation under different loading stages. The results showed that the difference in the thickness of the disturbed layer was the dominant factor of uneven settlement, finally controlling the inclination shape. Grouting reinforcement was conductive to improving the settlement of caisson foundation. The maximum total settlement, differential settlement and offset after reinforcement were reduced to 249.53 mm, 19.54 mm and 29.20 mm, respectively. The deformation mainly occurred in the loading stage before the platform construction, accounting for about 60 %. If it is considered to level the top surface, adjust the elevation and load center during the construction of platform, the incremental settlement, the north–south differential settlement and the offset of top surface corresponded to 94.26 mm, 10.31 mm and 17.52 mm, respectively. Finally, the reliability of above method was fully verified by comparing the measured data with calculated value. The results will provide certain ideas and methods for relevant engineering problems.