Abstract
Shallow rainfall triggered slope failures occur frequently in loess and loess-derived deposits across the South Island, New Zealand. These failures, which occur in both natural slopes and engineered cuttings, impact road infrastructure, residential housing and rural land use. When dry, the loess can form near vertical cuttings. However, with increase in moisture content loess slopes become susceptible to shallow slope failures. To date, the influence of negative pore-water pressure (suction) on the stability of loess slopes in New Zealand has not been well understood. In this paper, data from long term in situ field monitoring of rainfall, suction and volumetric water content from a loess slope in Banks Peninsula, Canterbury are presented with laboratory triaxial test results undertaken on undisturbed unsaturated loess samples. Field and laboratory soil responses to wetting and drying are compared, and the characteristics of rainfall events which reduce suction in situ and therefore slope stability are discussed.
Highlights
Loess and loess-derived soils are widespread across slopes in Canterbury, in the South Island of New Zealand (Fig. 1)
Typical mechanisms of slope failure include shallow slides, debris flow and tunnel gullying [1, 2, 7]. Because these materials are widespread in Canterbury, instability can be problematic for residential development, infrastructure and rural land use
Data from long-term field instrumentation of a natural loess slope is presented alongside laboratory data to examine the hydraulic state of loess in situ
Summary
Loess and loess-derived soils (e.g., loess colluvium) are widespread across slopes in Canterbury, in the South Island of New Zealand (Fig. 1) These Late Pleistocene and Postglacial (Holocene) age deposits were formed by aeolian processes and are primarily composed of siltsized grains [1-4]. Typical mechanisms of slope failure include shallow slides, debris flow and tunnel gullying (internal erosion) [1, 2, 7] Because these materials are widespread in Canterbury, instability can be problematic for residential development, infrastructure and rural land use. Data from long-term field instrumentation of a natural loess slope is presented alongside laboratory data to examine the hydraulic state of loess in situ Preliminary findings of this ongoing research programme are presented
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
