A number of field testing techniques, such as standard penetration test (SPT), cone penetration test (CPT), and Swedish weight sounding (SWS), are popularly used for in-situ characterisation. The screw driving sounding (SDS) method, which has been recently developed in Japan, is an improved version of the SWS technique and measures more parameters, including the required torque, load, speed of penetration and rod friction; these provide more robust way of characterising soil stratigraphy. It is a cost-efficient technique which uses a machine-driven and portable device, making it ideal for testing in small-scale and confined areas. Moreover, with a testing depth of up to 10-15m, it is suitable for liquefaction assessment. Thus, the SDS method has great potential as an in-situ testing method for geotechnical site characterisation, especially for residential house construction. In this paper, the results of SDS tests performed at a variety of sites in New Zealand are presented. The soil database was employed to develop a soil classification chart based on SDS-derived parameters. Moreover, using the data obtained following the 2010-2011 Christchurch Earthquake Se-quence, a methodology was established for liquefaction potential evaluation using SDS data. http://www.isc5.com.au/wp-content/uploads/2016/09/1345-2-ORENSE.pdf
Many large-scale earthquakes all over the world have highlighted the impact of soil liquefaction to the built environment, but the scale of liquefaction-induced damage experienced in Christchurch and surrounding areas following the 2010-2011 Canterbury earthquake sequence (CES) was unparalleled, especially in terms of impact to an urban area. The short time interval between the large earthquakes presented a very rare occasion to examine liquefaction mechanism in natural deposits. The re-liquefaction experienced by the city highlighted the high liquefaction susceptibility of soil deposits in Christchurch, and presented a very challenging problem not only to the local residents but to the geotechnical engineering profession. This paper summarises the lessons learned from CES, and the impacts of the observations made to the current practice of liquefaction assessment and mitigation.
A dramatic consequence of the Christchurch, New Zealand, earthquakes of 2010 and 2011 was the widespread liquefaction in the city. Part of the central business district (CBD) was badly affected by liquefaction but elsewhere large volumes of ejecta were not evident for those parts of the CBD where the upper layers in the soil profile are sandy gravel and gravelly sand. The purpose of the paper is to investigate the effect of the gravel permeability on the rise and dissipation of excess pore water pressure during cyclic loading of a soil profile idealised from Christchurch data. The Cyclic1D software, which performs one-dimensional non-linear effective stress site response analysis, was used. Permeability values associated with gravel were found to suppress the cyclic accumulation of excess pore water pressure in gravel layers. Given that there has not been any systematic measurement of the in situ permeability of the gravels in Christchurch, the modelling in the paper suggests that likely values for the bulk permeability of the gravel layers are within the range suggested in the geotechnical literature. However, the work reported is of wider application than Christchurch and emphasises the controlling influence of permeability on the accumulation and dissipation of cyclic pore pressures. VoR - Version of Record
