Abstract
Stress mobilisation and deformation of a slope are important for engineers to carry out reliable design of retaining systems. However, most case histories reported mainly on the response of pore water pressure (PWP), whereas knowledge about the stress deformation characteristics of slope is limited. In this study, a saprolitic soil slope was instrumented to monitor not only the responses of PWP but also horizontal stress and horizontal displacement. To assist in the interpretation of field data, a series of laboratory tests was conducted to characterise volume change behaviour of the soil taken from the site, under the effects of both net stress and suction. During a rainstorm event when positive PWP built up, a remarkably large displacement of 20 mm was recorded between 5.5- and 6-m depths, and the top 5 m of the slope exhibited translational downslope movement. This caused an increase in Bishop’s effective horizontal stress by 350 %, which reached a peak value close to 40 % of a Bishop’s effective passive stress. During the subsequent dry season when suction was recovered, an upslope rebound of 10 mm was recorded. Comparison of field and laboratory data reveals that the rebound was attributed to suction-induced soil shrinkage. This rebound led to a decrease in the Bishop’s effective horizontal stress previously built up during the storm event.
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Acknowledgments
The first author would like to acknowledge the research grant provided by the EU FP7 Marie Curie Career Integration Grant under the project “BioEPIC slope”, as well as the research travel fund supported by the Northern Research Partnership (NRP). The research grant HKUST6/CRF/12R provided by the Research Grants Council of the Government of the HKSAR and research grant (2012CB719805) from the National Basic Research Program (973 Program) provided by the Ministry of Science and Technology of the People’s Republic of China are also acknowledged. The authors would like to acknowledge the Geotechnical Engineering Office (GEO), Civil Engineering and Development Department (CEDD), the Government of the HKSAR, for funding the field monitoring work presented in this paper. The Head of GEO and the Director of CEDD are acknowledged for the permission to use of the base photograph in Fig. 1.
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Leung, A.K., Ng, C.W.W. Field investigation of deformation characteristics and stress mobilisation of a soil slope. Landslides 13, 229–240 (2016). https://doi.org/10.1007/s10346-015-0561-x
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DOI: https://doi.org/10.1007/s10346-015-0561-x