Select Liquefaction Case Histories from the 2010–2011 Canterbury Earthquake Sequence

Abstract

The 2010–2011 Canterbury earthquake sequence began with the 4 September 2010, Mw7.1 Darfield earthquake and includes up to ten events that induced liquefaction. Most notably, widespread liquefaction was induced by the Darfield and Mw6.2 Christchurch earthquakes. The combination of well-documented liquefaction response during multiple events, densely recorded ground motions for the events, and detailed subsurface characterization provides an unprecedented opportunity to add well-documented case histories to the liquefaction database. This paper presents and applies 50 high-quality cone penetration test (CPT) liquefaction case histories to evaluate three commonly used, deterministic, CPT-based simplified liquefaction evaluation procedures. While all the procedures predicted the majority of the cases correctly, the procedure proposed by Idriss and Boulanger (2008) results in the lowest error index for the case histories analyzed, thus indicating better predictions of the observed liquefaction response.

Stress History of Soils from Cone Penetration Tests

“…15d. Green et al (2014) identified sand layer 1 as the critical layer, yet the analyses also showed a thinner and shallower sandy layer that has a high probability of liquefaction. For both layers, the threshold YSR approach clearly recognizes these two sand layers as contractive.…”

“…A selected liquefaction case study at Site 19 in Brighton, a suburb of Christchurch, New Zealand that had experienced damages during the 2010-2011 sequences of large earthquakes will be used for illustration. Full details on the liquefaction site are given in Green et al (2014) and a quick summary of the post-processing of the CPTu sounding is presented in Fig. 15.…”

Assessment of CPT-based methods for liquefaction evaluation in a Liquefaction Potential Index (LPI) framework

“…2, 22 February 2011 Christchurch earthquake (e.g. Green et al, 2014). Ground motions from these events were recorded by a dense network of strong motion stations (e.g.…”

“…R&W98, MEA06 and I&B08), the peak ground accelerations (PGAs) at the ground surface were computed using the robust procedure discussed in detail by Bradley (2013a) and used by Green et al (2011Green et al ( , 2014 and Maurer et al (2014). The Bradley (2013a) procedure combines unconditional PGA distributions estimated by the Bradley (2013b) ground motion prediction equation, recorded PGAs from strong motion stations, and the spatial correlation of intra-event residuals to compute the conditional PGA distribution at sites of interest.…”

“…Also, it has been shown that the various LEPs used in today's practice can result in different FS liq values for the same soil profile and earthquake scenario (e.g. Green et al, 2014), and thus different LPI values. These differences have led to confusion as to which LEP is the most accurate, and whether the Iwasaki criterion is equally effective for all LEPs.…”