The Amethyst hydro scheme aims to address the increasing demand for power in the area. It involves diverting water from the Amethyst Ravine through penstocks in a 1040 m tunnel to a powerhouse on the floodplain of the Wanganui River. The 3.5 x 3.5 m…
This paper presents insights from recent advanced laboratory testing of undisturbed and reconstituted specimens of Christchurch silty-sands. The purpose of the testing was to establish the cyclic strength of silty-sands from sites in the Central Business District (CBD), where liquefaction was observed in 4 September…
Because of their lightweight, highly crushable and compressible nature, pumiceous sands are problematic from engineering and construction viewpoint. There has been very little information on their liquefaction characteristics and most empirical procedures available in evaluating the liquefaction potential of sands are derived primarily from hard-grained sands. To understand the…
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…