Prediction of bearing capacity of pile foundation in karst area based on model of metabolic GM (1,1)

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There are many methods to predict the bearing capacity of bridge pile foundation in karst area, and the accuracy of each method is different. In order to find out that the bearing capacity of pile foundation in karst area is affected by the change of cave size and predict the bearing capacity of pile foundation in karst area better, this paper is based on the engineering characteristics of pile foundation in karst area and the gray system theory and the finite element numerical simulation. The numerical simulation models of different cave sizes were used to analyze the changing rules of the bearing capacity of piles when the cave size was changed. At the same time, a metabolic GM (1,1) model was established, and the time response of pile foundation bearing capacity was deduced. Compared with the original GM (1,1) model, the P-S curve obtained from the FEM simulation was predicted. Finally, the engineering formula is used to validate the predicting formula of the pile bearing capacity in karst area. The results show that the bearing capacity of pile foundation in karst area is significantly affected by the size of caverns, of which the influence by cave caverns is the most obvious, and the bearing capacity of pile foundations decreases with the increase of cave spans. When the hole span increases from 6m to 9m, The bearing capacity decreased by 33.44%. Compared with the bearing capacity obtained by numerical simulation of the finite element method, the prediction error of the pile foundation by the metabolic GM (1,1) model can reach 1% and the precision is high. The obtained bearing capacity and precision of the obtained pile prediction formula can be used to predict the bearing capacity of pile foundation in karst area, which has some theoretical and engineering practical value.