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Images for Christchurch sand; more images...

Images, eqnz.chch.2010

Yes, it was a joke. The tours, that is, not the yard filled with earthquake-caused sand volcanos. They were very real. You can see one covering the driveway in this photo. The signs read as follows. "Tours run 1/2 hourly. $5.25 admission. Eftpos unavailable." "If you think this is bad... you should see the back!"

Research papers, University of Canterbury Library

Liquefaction of sandy soil has been observed to cause significant damage to infrastructure during major earthquakes. Historical cases of liquefaction have typically occurred in sands containing some portion of fines particles, which are defined as 75μm or smaller in diameter. The effects of fines on the undrained behaviour of sand are not however fully understood, and this study therefore attempts to quantify these effects through the undrained testing of sand mixed with non-plastic fines sourced from Christchurch, New Zealand. The experimental program carried out during this study consisted of undrained monotonic and cyclic triaxial tests performed on three different mixtures of sand and fines: the Fitzgerald Bridge mixture (FBM), and two Pinnacles Sand mixtures (PSM1 and PSM2). The fines content of each host sand was systematically varied up to a maximum of 30%, with all test specimens being reconstituted using moist tamping deposition. The undrained test results from the FBM soils were interpreted using a range of different measures of initial state. When using void ratio and relative density, the addition of fines to the FBM sand caused more contractive behaviour for both monotonic and cyclic loadings. This resulted in lower strengths at the steady state of deformation, and lower liquefaction resistances. When the intergranular void ratio was used for the interpretation, the effect of additional fines was to cause less contractive response in the sand. The state parameter and state index were also used to interpret the undrained cyclic test results – these measures suggested that additional fines caused less contractive sand behaviour, the opposite to that observed when using the void ratio. This highlighted the dependency on the parameter chosen as a basis for the response comparison when determining the effects of fines, and pointed out a need to identify a measure that normalizes such effects. Based on the FBM undrained test results and interpretations, the equivalent granular void ratio, e*, was identified from the literature as a measure of initial state that normalizes the effects of fines on the undrained behaviour of sand up to a fines content of 30%. This is done through a parameter within the e* definition termed the fines influence factor, b, which quantifies the effects of fines from a value of zero (no effect) to one (same effect as sand particles). The value of b was also determined to be different when interpreting the steady state lines (bSSL) and cyclic resistance curves (bCR) respectively for a given mixture of sand and fines. The steady state lines and cyclic resistance curves of the FBM soils and a number of other sand-fines mixtures sourced from the literature were subsequently interpreted using the equivalent granular void ratio concept, with bSSL and bCR values being back-calculated from the respective test data sets. Based on these interpretations, it was concluded that e* was conceptually a useful parameter for characterizing and quantifying the effects of fines on the undrained behaviour of sand, assuming the fines influence factor value could be derived. To allow prediction of the fines influence factor values, bSSL and bCR were correlated with material and depositional properties of the presented sand-fines mixtures. It was found that as the size of the fines particles relative to the sand particles became smaller, the values of bSSL and bCR reduced, indicating lower effect of fines. The same trend was also observed as the angularity of the sand particles increased. The depositional method was found to influence the value of bCR, due to the sensitivity of cyclic loading to initial soil fabric. This led to bSSL being used as a reference for the effect of fines, with specimens prepared by moist tamping having bCR > bSSL, and specimens prepared by slurry deposition having bCR < bSSL. Finally the correlations of the fines influence factor values with material and depositional properties were used to define the simplified estimation method – a procedure capable of predicting the approximate steady state lines and cyclic resistance curves of a sand as the non-plastic fines content is increased up to 30%. The method was critically reviewed based on the undrained test results of the PSM1 and PSM2 soils. This review suggested the method could accurately predict undrained response curves as the fines content was raised, based on the PSM1 test results. It also however identified some key issues with the method, such as the inability to accurately predict the responses of highly non-uniform soils, a lack of consideration for the entire particle size distribution of a soil, and the fact the errors in the prediction of bSSL carry through into the prediction of bCR. Lastly some areas of further investigation relating to the method were highlighted, including the need to verify the method through testing of sandy soils sourced from outside the Christchurch area, and the need to correlate the value of bCR with additional soil fabrics / depositional methods.

Images, eqnz.chch.2010

Christchurch Earthquake, the clean up begins, with residents clearing mud and sand off there properties onto the roadside.

Images, eqnz.chch.2010

great to see a large number of volunteers turn up to shovel out sand from properties within the Horseshoe Lake / Shirley area.

Images, eqnz.chch.2010

great to see a large number of volunteers turn up to shovel out sand from properties within the Horseshoe Lake / Shirley area.

Research papers, University of Canterbury Library

Among the deformation features produced in Christchurch by the September 4th Darfield Earthquake were numerous and widespread “sand volcanoes”. Most of these structures occurred in urban settings and “erupted” through a hardened surface of concrete or tarseal, or soil. Sand volcanoes were also widespread in the Avon‐ Heathcote Estuary and offered an excellent opportunity to readily examine shallow subsurface profiles and as such the potential appearance of such structures in the rock record.

Images, eqnz.chch.2010

Cleaning up the silt and sand from Hoon Hay properties. Here Laura, Robbie, and Ronny are part of the clean-up crew on Wyn Street.

Images, eqnz.chch.2010

The base of the tower on the right of this picture has sunk about 25cm so that the lower course of bricks have disappeared below ground level. Meanwhile the other end of the building has sunk about 50cm splitting the building into thirds. The sand you can see is what came bubbling up out of the ground due to liquifaction. Unfortunately the build...

Images, eqnz.chch.2010

The base of the tower on the right of this picture has sunk about 25cm so that the lower course of bricks have disappeared below ground level. Meanwhile the other end of the building has sunk about 50cm splitting the building into thirds. The sand you can see is what came bubbling up out of the ground due to liquifaction. Unfortunately the build...

Images, eqnz.chch.2010

The base of the tower on the right of this picture has sunk about 25cm so that the lower course of bricks have disappeared below ground level. Meanwhile the other end of the building has sunk about 50cm splitting the building into thirds. The sand you can see is what came bubbling up out of the ground due to liquifaction. Unfortunately the build...

Images, UC QuakeStudies

A photograph of a map of Christchurch in a temporary Civil Defence headquarters set up at the Mainland Foundation Ballpark after the 4 September 2010 earthquake. Red, green and blue markings on the map indicate where flooding, sand and closures are located. Post-it notes and a key with a tag reading, "Manchester" are attached to the map.