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7/31/2019 120729 Soil Research
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SOILFUTURE CHRISTCHURCH V2 |Dalia Al-Timimi Amanda Nakarmi Jeremy Wymer Chun Qin Zhang
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SOILFUTURE CHRISTCHURCH V2
600 - 380 Million Years ago. Sediments and Volca-noes orming.Between 370 Million Years ago and130 million years there is a lot o plate activity :pushing apart and uplit, beginning the break up.
85 Million years ago : Finally the break up o theNew Zealand Edge o Gondwana.
60 Million Years ago : The Tasman sea has ullyopended up. The New Zealand continant is wear-ring down and sinking
25 Million Years Ago : New Zealand is nearly sub-merged in the sea.
Last 20 Million Years : The uplit begins again subtly.But around 5 million years ago there was increaseduplit resulting in the ormation o the Southern Alps.
The Formation o New Zealand
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SOILFUTURE CHRISTCHURCH V2
CHRISTCHURCHCITYCANTERBURY
56-34 MA 34-23 MA 23-15 MA 15-5 MA 5-2 MA 2 MA-117000
The Changing Shape o New Zealand
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Banks Peninsula was once an island. Itwas the result o two Hawaiian shield
volcanoes errupting 12 - 6 million yearsago. Shield volcanoes are nearly entire-ly made o lava ows. During the lastglaciation the mainlaind and this pen-insula were joined up as the sea wasflled with outwashed sediments. This isknown as the Cantebury Plains todayand includes Christchurch City
Banks Peninsula
Banks Peninsula
Christchurch City
Glaciers
Outwash and aggradation
The Last Glaciation sometimes reered to as the Last Ice Age occured around 100 000to 10 000 years ago. A glacier is a large mass o ice the ows downwards. They car-ry rocks and soil with them. As glaciers melt they create valleys and deposit sediments.This map shows the areas o Cantebury that have ormed because o this glaciation.
New Zealand During the Last Glaciation
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Greywacke and agrillite
Post-glacial alluvium and dune sand
Flow rhyolite, breccia and obsidian
Sandstone, siltstone and claystone
Basalt ows
Andesite
Volcanic and associated intrusive rocks Sedimentary and metamorphic rocks
The Geology o Christchurch and Surrounding Areas
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0 100 250km
Defenitions of Soil Orders found in Christchurch
Pallic Soils
Pallic Soils have pale coloured subsoils, usually light yellowish
brown or olive yellow, due to low contents of iron oxides.
The soils have weak structure and high density. Root extension is
limited and the drainage of water through the soils is slow.
Pallic Soils occur predominantly in the eastern parts of North andSouth Islands and the Manawatu; in places that are dry in
summer and moist in winter. In many areas the surface horizons
are waterlogged in winter due to the slow drainage. The
precipitation is usually between 500 and 1000 mm per year.
They occur in parent materials which a re not strongly altered by
weathering. The soils are only weakly leached with moderate to
high levels of calcium and other cations
Gley Soils
Gley Soils are soils that have been strongly affected by waterlog-
ging and have been reduced to depth.
They have light grey subsoils usually with reddish brown or brown
mottles. The grey colours extend to more that 90cm depth.
Waterlogging occurs in winter and spring and some soils remain
wet throughout the year.
They often occur in low parts of the landscape where there are
high ground water tables
Brown Soils
Brown Soils have a brown or yellow-brown subsoil below a dark
grey-brown topsoil. The brown colour is due to thin coatings of
iron oxides which have weathered from the parent material.
The majority of Brown Soils occur in places in which summer
dryness is uncommon and which are not waterlogged in winter.
The precipitation is usually more that 1000 mm per year although
it may be less in some stony soils.
They occur in loess, alluvium or slope debris parent materials
which are little altered by weathering. The soils are however
usually strongly leached and are acid with low levels of calcium
and other basic cations. They are the most extensive New
Zealand soils, particularly in the South Island mountainsPodzol
Soil Types
Melanic
Organic
Recent
Brown
RawPallic
Giley
Ultic
Brown-story
Pumice
Granular Allophanic Oxidic
Geographic Distribution o the Dominant Soil Types in New Zealand
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SOILFUTURE CHRISTCHURCH V2
Urban Areas of Christchurch
1:500,000
0 5 km 1 0k m 1 5k m
04.CBD
Weathering
UWSWMWHCCWRW
UnweatheredSlightly WeatheredModerately WeatheredHighly WeatheredCompletely/Extr. WeatheredResidual Soil
Source Key
Undrained Shear Strength
VSSFStVStHFb
Very softSoftFirmStiffVery StiffHardFriable
Cu (kPa)200
Relative Density
VLLMDDVD
Very looselooseMedium DenseDenseVery Dense
01.Kairaki BeachBorehole Location
DataSoil Prole
SPT/Particle SizeSoil Description
Colour
- 1.5 W VL
- 2.3 W VS
- 3.0 W MD
- 5.1 W L
- 6.1 W L
- 7.5 W MD
- 15.0 W MD
02.Wainoni
DataSoil Prole
SPT/Particle SizeSoil Description
Colour
- 1.3 M VS
- 1.9 W VL
- 3.0 W VS
- 8.0 W L
- 13.5 W D
- 15.0 W VSt
03.Hallswell
DataSoil Prole
SPT/Particle SizeSoil Description
Colour
- 0.8 W S
- 1.5 W D
- 6.0 W MD
- 7.0 W F
- 7.5 W VS
- 10.5 W F
- 22.0
DataSoil Prole
SPT/Particle SizeSoil Description
Colour
- 0.8 W VL
- 1.5 MW VL
- 5.5 W L
- 7.0 W L
- 10.5 MW L
- 10.5 W VL
- 19.0
- 14.5 W VL
Characteristics Soil Profles
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04.Avondale
DataSoil Prole
SPT/Particle SizeSoil Description
Colour
- 0.8 D L
- 2.8 M-W F- 3.0 W L
- 3.5 M S
- 4.7 W L
- 7.5 W L
- 8.0 W L- 8.2 W L
- 9.0 W D
- 9.8 W D
- 10.5 W D
- 11.7 W MD
- 15.0
06.Bexley
DataSoil Prole
SPT/Particle SizeSoil Description
Colour
- 0.8 D
- 2.2 M VS
- 4.5 MD
- 6.0 W MD
- 15.0
08.Richmond
DataSoil Prole
SPT/Particle SizeSoil Description
Colour
- 1.0
- 3.5 W VS
- 4.0 W MD
- 6.0 W MD
- 17.0 W VD
- 19.0 W VD
07.Burwood
DataSoil Prole
SPT/Particle SizeSoil Description
Colour
- 0.8
- 1.5 M
- 2.9 W VS
- 4.5 W MD
- 6.0 W MD
- 10.5 W MD
- 11.2 SW MD
- 15.0 W D
- 0.35 D L
- 3.1 W L
- 4.8 W MD
Colour
09.Spencerville
DataSoil Prole
SPT/Particle SizeSoil Description
- 5.2 W MD- 5.4 W MD
- 5.0 W MD
- 5.6 W MD
- 5.8 W MD
- 7.5 W D
- 10.7 W MD
- 11.4 W MD
- 11.6 S MD
- 13.0 W MD
- 14.8 W MD
- 15.3 W MD
- 17.3 W D
- 19.3 W D
DataSoil Prole
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2 cm
Gravel and Gravelly Soils
Clean Gravels
Gravels with nes
Well graded gravels or gravel - sand mixtures,little or no ne
Pedon Scale Core Section Aggregate Scale Micropore scale
Silty gravels, gravel-sand-silt mixtures A loose granular substance carried byrunning water
A loose granular substance
loose granular substance, slightlyweathered
loose granular substance, highlyweathered
Material characteristic of boggy, acidground consisting of partlydecomposed vegetable matter.
Very low porosity -angular grains, many sizes(poor sorting)
High porosity -rounded grains, many sizes(poor sorting)
High porosity -rounded grains, many sizes(poor sorting)
High porosity -
rounded grains, uniform size (goodsorting)
High porosity -rounded and angular grains, manysizes(good sorting)
High porosity -angular and rounded grains, manysizes
(poor sorting)
Strong thin platey structure
Sand and Sandy Soils
Clean Sands
Sands with nes
Well graded sands or gravelly sands, little or nones
Silty sands, sand-silt mixtures
Silt Soils
Peat Soils
Fine sand carried by running water anddeposited as a sediment.
A soil like material consisting of partlydecomposed vegetable matter
WHITE COLOUR ASSIGNED TO PORE AND BLACK TO SOIL
Soil Types, Structure and Porosity
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The main soil types o Christchurch consist o granular substancessuch as sands, gravels, non-plastic soils and their mixtures. Thesegranular soils are the main reason or liqueaction. These soils derivetheir stiness and strength through grain to grain contact stresses.Shallow soils have small grain to grain contact stresses, so they arerelatively sot and weak. Soils at great depth have large grain to
grain contact stresses so they are relatively sti and strong.
The soil types evident in the borehole samples are loose. Loose soilshave more voids in their inherent structure (since they were not wellcompacted when deposited) Hence, when shaken, they show largetendency or densifcation (contraction) which in turn leads to rapidpore water pressure build up and eventual liqueaction in only ewcycles o strong shaking. Since these soils are loosely packed andare highly deormable (compressible), liqueaction will be severelymaniested and will result in very large ground movements and nearlycomplete loss o load carrying capacity. This is why loose soils areparticularly prone to liqueaction and show very severe consequenc-es o liqueaction. Very Dense soils are rare in the borehole samples.Very dense soils will allow or limited tendency or densifcation andhence produce low excess pore water pressures and thereore would
have a much higher liqueaction resistance. Clays are not evidentin Christchurch soils. Clayey soils in general, derive stiness andstrength rom an additional mechanism (cohesion) and hence areconsidered non-liquefable.
Characteristics o Christchurch Soil
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DENSE SEDIMENT
SATURATED LOOSE SEDIMENT
The young sediment christchurch is built on means the city is prone to the effects ofliquefaction during an earthquake event. The city has been noted by international expertsas the most prone to liquefaction in the world. Liquefaction variation is determined by theepicentre location, magnitude, depth, duration and geological conditions.Flat areas such as this, where the water table sits only a few meters under the surface,release a build up of pressure through sand boils and waterspouts in many areas andin lateral spreading and cracking near rivers. This occurs as waters are removed from
the lower lying saturated loose sediment underground during the shaking. The wateris forced up through weak points in the denser sediment just below the surface. As thisoccurs the loss of water in the lower layers gives way to compaction, producing a varietyof effects to the natural and built environment.
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DENSE SEDIMENT
COMPACTED SEDIMENT
SETTLED FOUNDATIONSWeakened soil can cause buildingsto sink or tilt as compaction occures.this results in deormation or crackingo the building.
SUBSIDED LANDAs the lower sediment compacts andmoisture is orced upwards, largechunks o land subside, damagingbuildings above and leaving largesteps in the landscape.
FLOATED SERVICESAs the pressure increasespipes become buoyant andoat up through the ground.manholes are pushed upout o the roads and pipesbecome damaged andsevered in places, leakingtheir contents into the earth.
SAND BOILSStrong surace evidence thatliqueaction has occured. thepressure in the ground orces theliquifed silt upwards and out o theground covering the surace in mudand water.
WEAKENED SOILTrees, power poles, lampposts and similar objectsare unable to be supportedproperly by the liquifedground.
LATERAL SPREADINGEarth on river banks slide towardseach other under the pressurecausing signifcant cracks to openup. this may extend quite somedistance back rom the river itsel.
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The map indicates areas of Liquefaction ground damagepotential dened for Christchurch.
High Liquefaction PotentialAreas in Christchurch rated High Liquefaction potential maybe affected by lateral spreading and signicance groundsubsidence that is likely to be greater than 300mm.
Moderate Liquefaction PotentialAreas in Christchurch rated High Liquefaction potential maybe affected by 100-300mm of ground subsidence.
Low Liquefaction PotentialAreas in Christchurch rated Low Liquefaction Potential maybe affected up to 100mm of g round subsidence.
High Liquefaction potential may be expectedAreas in Christchurch rated High Liquefaction potential maybe expected are very likely to be affected by Liquefaction,with the data that was provided at this stage it is difcult to
determine the accurate information.
Low Liquefaction potential may be expectedAreas in Christchurch rated Low Liquefaction potential may beexpected are very unlikely to be affected by Liquefaction, withthe data that was provided at this stage it is difcult todetermine the accurate information.
No Liquefaction not predictedAreas in Christchurch rated No Liquefaction not predictedare areas that unlikely for Liquefaction to occur
PortHills
Parklands
Brooklands
Belfast
SH1
PapanuiAirport
SH1
SH1 Hornby
SH73
Avon-
Heathcote
Estuary
Ferrymead
LinwoodRiccarton
Wainoni
WaimakaririRive
r
Waim
akaririRiv
er
High Liquefaction potential
Moderate Liquefaction potential
Low Liquefaction potential
High Liquefaction potential may be expected
Low Liquefaction potential may be expected
No Liquefaction / not predicted
Major Roads
Rivers
Christchurch City Boundary
Port Hills - No Liquefaction expected
N
8km6420
Scale: 1:100,000
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SOILFUTURE CHRISTCHURCH V2
Areas where the Water table is at its highest is very like;y for Liquefaction ground damage tooccur during an Earthquake, other areas with a Lower water table is unlikely for Liquefactionground damage to occur.
013 245678910111213141516
-40
-30
-20
-10
0
10
20
30
Elevation(m)
RussleyRoad
WaimainRoad
RollestonAvenue
FitzgeraldAvenue
BexeyRoad
Distance from Pegasus Bay (km)
Sea Level Water-table
Ground Surface
Top of Gravel
4km3210
Scale: 1:100,000
RussleyRoad
WaimainRoad
RollestonAvenue
FitzgeraldAvenue
BexeyRoad
East - West Cross Section through Christchurch
40m
CBD
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