Acknowledgements:
The work was primarily supported by the Centre for Slope Safety (AoE/E-603/18) of the Research Grants Council of the Hong Kong SAR Government. C.K.F. Lee and J. Wu were supported by National Natural Science Foundation of China (#31922090) and HKU seed fund for basic research (#202011159154). C.K.F. Lee was also in part supported by the HKU 45th round PDF scheme.