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Images for earthquake liquefaction; more images...

Images, UC QuakeStudies

A Transfield Services worker entering a manhole in north-east Christchurch. Piles of liquefaction are around the man hole. In the background, is one of the portable toilets set up after the 22 February 2011 earthquake to service areas of the city without operational sewers.

Research papers, University of Canterbury Library

Well-validated liquefaction constitutive models are increasingly important as non-linear time history analyses become relatively more common in industry for key projects. Previous validation efforts of PM4Sand, a plasticity model specifically for liquefaction, have generally focused on centrifuge tests; however, pore pressure transducers installed at several free-field sites during the Canterbury Earthquake Sequence (CES) in Christchurch, New Zealand provide a relatively unique dataset to validate against. This study presents effective stress site response analyses performed in the finite difference software FLAC to examine the capability of PM4Sand to capture the generation of excess pore pressures during earthquakes. The characterization of the subsurface is primarily based on extensive cone penetration tests (CPT) carried out in Christchurch. Correlations based on penetration resistances are used to estimate soil parameters, such as relative density and shear wave velocity, which affect liquefaction behaviour. The resulting free-field FLAC model is used to estimate time histories of excess pore pressure, which are compared with records during several earthquakes in the CES to assess the suitability of PM4Sand.

Research papers, University of Canterbury Library

Semi-empirical models based on in-situ geotechnical tests have become the standard of practice for predicting soil liquefaction. Since the inception of the “simplified” cyclic-stress model in 1971, variants based on various in-situ tests have been developed, including the Cone Penetration Test (CPT). More recently, prediction models based soley on remotely-sensed data were developed. Similar to systems that provide automated content on earthquake impacts, these “geospatial” models aim to predict liquefaction for rapid response and loss estimation using readily-available data. This data includes (i) common ground-motion intensity measures (e.g., PGA), which can either be provided in near-real-time following an earthquake, or predicted for a future event; and (ii) geospatial parameters derived from digital elevation models, which are used to infer characteristics of the subsurface relevent to liquefaction. However, the predictive capabilities of geospatial and geotechnical models have not been directly compared, which could elucidate techniques for improving the geospatial models, and which would provide a baseline for measuring improvements. Accordingly, this study assesses the realtive efficacy of liquefaction models based on geospatial vs. CPT data using 9,908 case-studies from the 2010-2016 Canterbury earthquakes. While the top-performing models are CPT-based, the geospatial models perform relatively well given their simplicity and low cost. Although further research is needed (e.g., to improve upon the performance of current models), the findings of this study suggest that geospatial models have the potential to provide valuable first-order predictions of liquefaction occurence and consequence. Towards this end, performance assessments of geospatial vs. geotechnical models are ongoing for more than 20 additional global earthquakes.

Images, UC QuakeStudies

Bricks from a demolished chimney lie on top of thick liquefaction silt in front of a house in St Albans. The photographer comments, "Our friend Chris Hutching's house. The front lawn and carport have 30cm or more of silt piled on top. He also had to remove a shaky chimney".

Images, UC QuakeStudies

Bricks from a demolished chimney lie on top of thick liquefaction silt in front of a house in St Albans. The photographer comments, "Our friend Chris Hutching's house. The front lawn and carport have 30cm or more of silt piled on top. He also had to remove a shaky chimney".

Images, UC QuakeStudies

Damage to Medway Street in Richmond. The road surface is cracked and buckled, and covered in liquefaction silt. A temporary road sign restricting speed to 30 is visible, with road cones behind. The photographer comments, "Medway St, between Woodchester Ave and River Rd. Woodchester Ave on right just beyond the 30 sign".

Images, UC QuakeStudies

Damage to the garden of a house in Richmond. Liquefaction is visible among the plants and on the driveway. The photographer comments, "These photos show our old house in River Rd and recovery work around Richmond and St Albans. Back lawn under 10cm of water and silt".

Research papers, University of Canterbury Library

The Canterbury Earthquake Sequence 2010-2011 (CES) induced widespread liquefaction in many parts of Christchurch city. Liquefaction was more commonly observed in the eastern suburbs and along the Avon River where the soils were characterised by thick sandy deposits with a shallow water table. On the other hand, suburbs to the north, west and south of the CBD (e.g. Riccarton, Papanui) exhibited less severe to no liquefaction. These soils were more commonly characterised by inter-layered liquefiable and non-liquefiable deposits. As part of a related large-scale study of the performance of Christchurch soils during the CES, detailed borehole data including CPT, Vs and Vp have been collected for 55 sites in Christchurch. For this subset of Christchurch sites, predictions of liquefaction triggering using the simplified method (Boulanger & Idriss, 2014) indicated that liquefaction was over-predicted for 94% of sites that did not manifest liquefaction during the CES, and under-predicted for 50% of sites that did manifest liquefaction. The focus of this study was to investigate these discrepancies between prediction and observation. To assess if these discrepancies were due to soil-layer interaction and to determine the effect that soil stratification has on the develop-ment of liquefaction and the system response of soil deposits.

Images, UC QuakeStudies

A large crack in the road surface at the intersection of Medway Street and River Road, where River Road has slumped towards the river. The photographer comments, "Medway Street is a buckled mess of broken seal and liquefaction. 79 Medway St is on the right - taken at the corner of Medway St and River Rd".

Images, UC QuakeStudies

Water and liquefaction flows into the Avon River in Richmond. The water level is very high, and the water is cloudy with silt. The photographer comments, "Water from Dudley Creek took a shortcut across the road into the Avon. It doesn't have much of a drop from the road to the river".

Images, UC QuakeStudies

Water and liquefaction run down the driveway of a house in Richmond. The driveway level is noticeably higher than the footpath in front. The photographer comments, "These photos show our old house in River Rd and recovery work around Richmond and St Albans. A house along the block has water running out the driveway".

Images, UC QuakeStudies

The ruins of the historic Durham Street Methodist Church in the aftermath of the 22 February 2011 earthquake. The only parts of the building still upright are those supported by steel braces placed there after the 4 September 2010 earthquake to strengthen the building as it awaited repairs. Rubble has spilled out onto the street, knocking over the safety fences that were also erected after September. Silt from liquefaction has covered the road around the church.

Images, UC QuakeStudies

The ruins of the historic Durham Street Methodist Church in the aftermath of the 22 February 2011 earthquake. The only parts of the building still upright are those supported by steel braces placed there after the 4 September 2010 earthquake to strengthen the building as it awaited repairs. Rubble has spilled out onto the street, knocking over the safety fences that were also erected after September. Silt from liquefaction has covered the road around the church.

Images, UC QuakeStudies

The ruins of the historic Durham Street Methodist Church in the aftermath of the 22 February 2011 earthquake. The only parts of the building still upright are those supported by steel braces placed there after the 4 September 2010 earthquake to strengthen the building as it awaited repairs. Rubble has spilled out onto the street, knocking over the safety fences that were also erected after September. Silt from liquefaction has covered the road around the church.

Images, UC QuakeStudies

A photograph of tents and shipping containers in Hagley Park which were to be part of the Ellerslie International Flower Show. The show was cancelled in the aftermath of the 22 February 2011 earthquake. In the foreground of this photograph, liquefaction can still be seen on the grass.

Research papers, University of Canterbury Library

Earthquake-triggered soil liquefaction caused extensive damage and heavy economic losses in Christchurch during the 2010-2011 Canterbury earthquakes. The most severe manifestations of liquefaction were associated with the presence of natural deposits of clean sands and silty sands of fluvial origin. However, liquefaction resistance of fines-containing sands is commonly inferred from empirical relationships based on clean sands (i.e. sands with less than 5% fines). Hence, existing evaluation methods have poor accuracy when applied to silty sands. Also, existing methods do not quantify appropriately the influence on liquefaction resistance of soil fabric and structure, which are unique to a specific depositional environment. This study looks at the influence of fines content, soil fabric (i.e. arrangement of soil particles) and structure (e.g. layering, segregation) on the undrained cyclic behaviour and liquefaction resistance of fines-containing sandy soils from Christchurch using Direct Simple Shear (DSS) tests on soil specimens reconstituted in the laboratory with the water sedimentation technique. The poster describes experimental procedures and presents early test results on two sands retrieved at two different sites in Christchurch.

Images, UC QuakeStudies

A photograph of the earthquake damage to St Paul's School in Dallington. Large cracks can be seen in the surface of the asphalt. Silt from liquefaction is visible in front of the school buildings. Tape has been placed on the building to keep people away.

Images, UC QuakeStudies

Damage to a house in Richmond. The brick wall is badly cracked and twisted, and some bricks have fallen, exposing the lining paper below. The driveway is cracked and covered in liquefaction. The photographer comments, "These photos show our old house in River Rd. More shaking damage on the east wall of the living room at our house".

Images, eqnz.chch.2010

And, yes, the newspaper always gets through! The Press newspapers were delivered in our area of Hoon Hay in the hours after the earthquake.

Images, UC QuakeStudies

Students at the University of Canterbury relaxing inside the UCSA's "Big Top" tent. The tent was erected to provide support for students in the aftermath of the 22 February 2011 earthquake. The students have spent the day clearing liquefaction from Christchurch properties as part of the Student Volunteer Army.

Images, UC QuakeStudies

Damage to a residential property on Hood Avenue in Pines Beach, after the September 4th earthquake. The house is on a lean due to liquefaction.