A composite function model for predicting the ground reaction curve on a trapdoor

Abstract This paper proposes a composite function model to describe the ground reaction curve (GRC) on a trapdoor. The characteristics of the GRC were analysed in detail in combination with the development of soil arching and the shear surface. The parameters in the proposed model for two-dimensional (2D) and three-dimensional (3D) cases were determined by suggesting new multi-arch models and the results of existing trapdoor model tests. The multi-arch models consist of three parts: the upper end-bearing arch, the stability zone and the lower friction arch. A formula for predicting the height of the friction arch zone was deduced. The effectiveness of the proposed models was demonstrated by comparing the calculated results using the proposed models with the measured data of laboratory model tests. Results showed that the proposed model can describe the trend of the full GRC accurately and the variations in the minimum and ultimate soil arching ratios and load recovery index with increasing burial depth. Finally, the effects of model parameters on the GRC were analysed.