The soil site spectra for site classes D and E in the current NZ design code impose a significant increase in the displacement demands, between 50 and 300% for a structure with a period of 1.0s or longer, compared with a rock site (class A/B)…
Ground engineers routinely use simple relationships – rules of thumb – to obtain soil parameters and to design ground works. Some of these have a sound theoretical basis and can be applied generally while some are purely empirical and so should be applied only within…
This paper presents a summary of land damage observed in the Port Hills of Christchurch, New Zealand, following the earthquake sequence of 4 September 2010, in particular the land damage associated with a period of high seismic activity which commenced in February 2011. The earthquakes…
In pseudo-static analysis, the Mononobe-Okabe (M-O) solution is typically applied to determine seismic earth pressures acting on retaining walls where resulting displacements are relatively large. These equations require the input of a horizontal seismic coefficient which is frequently chosen to be equivalent to the free-field…
Piezocone penetration testing (CPTu) is a widely used investigation method for geotechnical analysis and liquefaction assessments. In addition to recording tip resistance (qc) and sleeve friction (fs), pore water pressure (u) is measured by a pressure transducer via a porous filter commonly located behind the…
Following the Canterbury earthquakes, affected land was zoned to indicate the potential of future land damage due to liquefaction or lateral spreading under earthquake loading. In order to apply a corresponding zoning for unaffected land, as well as land in other provinces, a zoning system…
Simplified procedures for evaluating liquefaction triggering potential use the nonlinear shear stress reduction factor, rd, to estimate the peak earthquake-induced cyclic shear stress within the soil strata. Previous studies have derived rd by considering the response of representative ground profiles subjected to input ground motions…
The assessment of a soil’s liquefaction potential can often have major financial implication for infrastructure projects. An overly conservative assessment can lead to unnecessary expenditure on foundations or ground improvement. The assessment of liquefaction potential in recent deposits of alluvial soils with grains of lithic…
This paper presents a simplified procedure for predicting earthquake-induced level and sloped ground failure, namely liquefaction and shear failure. It consists of a framework where cyclic stress ratio (CSR), static stress ratio (SSR) and undrained shear strength (USS) are formulated considering simple shear conditions, which…
Predicting the severity of liquefaction induced ground damage is the key outcome from a liquefaction assessment. Ishihara (1985) developed a simple and logical method to predict the occurrence of sand boils, ground fissures and other features of liquefaction damage. This paper examines the effectiveness of…