Various in situ testing techniques are commonly employed to obtain geotechnical parameters for use in analyses and design. Some of the more popular field tests include standard penetration tests (SPTs), cone penetration tests (CPTs) and Swedish weight sounding (SWS). SPT and CPT are commonly preferred for large-scale projects, but they are expensive when implemented for small-scale constructions. SWS is highly portable and economical but poor in classifying soils. The screw driving sounding (SDS) test, which has been recently developed in Japan, is an improved version of SWS and can measure more parameters, including the required torque, load, speed of penetration and rod friction, and thereby provides a robust way of characterising soil stratigraphy. It is cost efficient and uses a machine-driven and portable device, making it suitable for testing in confined areas. Moreover, with a testing depth of 10–15 m, it is ideal for characterising shallow deposits. In this paper, the SDS test is introduced and the results of its application to various New Zealand sites are discussed. Moreover, a number of correlations between SDS parameters and CPT/SPT data are presented. The results prove that SDS can be an effective alternative for soil characterisation, particularly in residential areas and roading projects.
Although located about 200 km away from the epicentre of the 2016 Kaikōura Earthquake, the waterfront areas of Wellington City suffered varying degrees of damage as a result of soil liquefaction and associated ground deformations. This paper presents a summary of the major observations made following reconnaissance inspections of the geotechnical effects caused by the earthquake, with emphasis on the ground performance in the affected areas near the waterfront. Except for CentrePort, summarised elsewhere in this Special Issue, the inspections concentrated mostly on the waterfront areas and the impact to buildings built on reclaimed lands. Cracks and minor ground subsidence were observed in many parts of the waterfront, but the damage was less than that in CentrePort where significant liquefaction-induced damage was evident. The age of reclamation appears to have significant effect on the distribution of liquefaction-induced damage, while reclaimed areas where improvement techniques have been implemented performed well.
During the recent devastating earthquakes in Christchurch, many residential houses were damaged due to widespread liquefaction of the ground. In-situ testing is widely used as a convenient method for evaluating liquefaction potential of soils. Cone penetration test (CPT) and standard penetration test (SPT) are the two popular in situ tests which are widely used in New Zealand for site characterization. The Screw Driving Sounding (SDS) method is a relatively new operating system developed in Japan consisting of a machine that drills a rod into the ground by applying torque at seven steps of axial loading. This machine can continuously measure the required torque, load, speed of penetration and rod friction during the test, and therefore can give a clear overview of the soil profile along the depth of penetration. In this paper, based on a number of SDS tests conducted in Christchurch, a correlation was developed between tip resistance of CPT test and SDS parameters for layers consisting of different fines contents. Moreover, using the obtained correlation, a chart was proposed which relates the cyclic resistance ratio to the appropriate SDS parameter. Using the proposed chart, liquefaction potential of soil can be estimated directly using SDS data. As SDS method is simpler, faster and more economical test than CPT and SPT, it can be a reliable alternative in-situ test for soil characterization, especially in residential house constructions.
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