Study on the ultimate bearing capacity of a strip footing influenced by an irregular underlying cavity in karst areas
Lianheng Zhao, Shan Huang, Zhonglin Zeng, Rui Zhang, Gaopeng Tang, Shi Zuo
Abstract
This study investigates the ultimate bearing capacity and typical failure mechanisms of a rough strip footing constructed above an irregular cavity using the upper bound finite element limit analysis (UBFELA) method. A novel method based on the inverse discrete Fourier transform (IDFT) theory is employed to generate and quantitatively describe the irregular shape of natural cavities. Parametric studies are performed to study the influence of several variables, including the ratio of the cavity size to the strip footing width (D/B), the ratio of the cover depth to the footing width (H/B), the internal friction angle (φ), the direction angle of the long axis of the cavity (θ) and the shape descriptors of the cavity (D2, D3, and D8). Numerical results are presented in the form of dimensionless charts for the bearing capacity numbers (Pu/c). The obtained failure modes present significant asymmetry and a critical region is found to be greatly affected by the size of the cavity (D/B), the cavity depth (H/B) and the internal friction angle (φ).