Search

found 152 results

Images for earthquake liquefaction; more images...

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. The liquefaction behaviour of Christchurch fines-containing (silty) sands is investigated through a series of Direct Simple Shear (DSS) tests. This type of test better resembles earthquake loading conditions in soil deposits compared to cyclic triaxial tests. Soil specimens are reconstituted in the laboratory with the water sedimentation technique. This preparation method yields soil fabrics similar to those encountered in fluvial soil deposits, which are common in the Christchurch area. Test results provide preliminary indications on how void ratio, relative density, preparation method and fines content influence the cyclic liquefaction behaviour of sand-silt mixtures depending on the properties of host sand and silt.

Images, UC QuakeStudies

Liquefaction silt covers the ground in front of the Shirley Medical Centre, and more silt is piled beside the entrance. The photographer comments, "These photos show our old house in River Rd and recovery work around Richmond and St Albans. The local medical centre is seriously silted up".

Images, UC QuakeStudies

Liquefaction silt covers the ground in front of the Shirley Medical Centre, and more silt is piled beside the entrance. The photographer comments, "These photos show our old house in River Rd and recovery work around Richmond and St Albans. The local medical centre is seriously silted up".

Images, UC QuakeStudies

Trees alongside the Avon River in Richmond. The river level is high, and the water is grey with silt. One of the trees is leaning towards the river. The photographer comments, "High river levels because of liquefaction in the Avon. Near 373 River Rd, Richmond".

Images, UC QuakeStudies

A photograph of a portaloo outside a residential property in Christchurch. After the 22 February 2011 earthquake, many houses had no running water and were forced to use chemical toilets or portaloos placed along the street. There is flooding and liquefaction on the street in the foreground. Liquefaction silt has been piled on the side of the road and a road cone placed in front.

Images, UC QuakeStudies

A photograph of emergency management personnel examining a block of earthquake-damaged rooms at Stonehurst Accommodation on Gloucester Street. The bottom storey of the block has collapsed and the remaining rooms are now resting on an incline. The front walls of these rooms have also collapsed and the rubble has spilled in to the courtyard in front. Cordon tape has been draped across the courtyard in front of the rubble. In the foreground there is liquefaction on the ground from a liquefaction volcano.

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

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

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".