Seismic triggering of submarine slides in soft cohesive soil deposits

The geological profile of many submerged slopes on the continental shelf consists of normally to lightly overconsolidated clays with depths ranging from a few meters to hundreds of meters. For these soils, earthquake loading can generate significant excess pore water pressures at depth, which can bring the slope to a state of instability during the event or at a later time as a result of pore pressure redistribution within the soil profile. Seismic triggering mechanisms of landslide initiation for these soils are analyzed with the use of a new simplified model for clays which predicts realistic variations of the stress-strain-strength relationships as well as pore pressure generation during dynamic loading in simple shear. The proposed model is implemented in a finite element program to analyze the seismic response of submarine slopes. These analyses provide an assessment of the critical depth and estimated displacements of the mobilized materials and thus are important components for the estimation of submarine landslide-induced tsunamis. © 2003 Elsevier B.V. All rights reserved.

Comparisons of operating envelopes for contaminated soil stabilised/solidified with different cementitious binders

This work initiated the development of operating envelopes for stabilised/solidified contaminated soils. The operating envelopes define the range of operating variables for acceptable performance of the treated soils. The study employed a soil spiked with 3,000 mg/kg each of Cd, Cu, Pb, Ni and Zn, and 10,000 mg/kg of diesel. The binders used for treatment involved Portland cement (CEMI), pulverised fuel ash (PFA), ground granulated blast furnace slag (GGBS) and hydrated lime (hlime). The specific binder formulations were CEMI, CEMI/PFA = 1:4, CEMI/GGBS = 1:9 and hlime/GGBS = 1:4. The water contents employed ranged from 13 % to 21 % (dry weight), while binder dosages ranged from 5 % to 20 % (w/w). We monitored the stabilised/solidified soils for up to 84 days using different performance tests. The tests include unconfined compressive strength (UCS), hydraulic conductivity, acid neutralisation capacity (ANC) and pH-dependent leachability of contaminants. The water content range resulted in adequate workability of the mixes but had no significant effect on leachability of contaminants. We produced design charts, representing operating envelopes, from the results generated. The charts establish relationships between water content, binder dosage and UCS; and binder dosage, leachant pH and leachability of contaminants. The work also highlights the strengths and weaknesses of the different binder formulations. © 2013 Springer-Verlag Berlin Heidelberg.