5th Intensive Course on Soil Micromorphology Naples 2001 12th - 14th September Image Analysis...

5th Intensive Course on Soil Micromorphology

Naples 2001

12th - 14th September

Image Analysis

Lecture 11

Engineering Applications of Soil

Micromorphology/ Microfabric Analysis

5th Intensive Course on Soil Micromorphology - Naples 2001Image Analysis - Lecture 11: Engineering Applications.

Engineering Applications

Quantitative Methods

•Examples of Intensity Gradient Analysis

•New methods for porosity analysis

Dynamic Studies

Applications to a Palaeosol of coast of Hong Kong


Intensity Gradient/Orientation Analysis

There is evidence to show particles do align perpendicular to principal stress direction.

BUT

Orientation is far from complete.


How does orientation vary within a sample?

Over 350 separate estimates of orientation were made on this sample.

The location of each image is indicated by the + while the length of the line and direction indicate the degree of anisotropy and the preferred direction respectively.

In this sample the microfabric is very uniform

These results were obtained with a fully automatic system


Other samples are less uniform

Uniform in places, but shear discontinuities evident


Microfabric changes on shearing


Detail across a failure zone

At the edges of the failure zone, the Index of Anisotropy is less than outside region, but there is a sharp change in angle on either side - suggesting a kink zone failure.


New developments in Porosity Studies

Original Image Binary Version of Restored Image

Flow of fluids is high influenced by path length

Which is shortest path across image?


Path highlighted is shortest continuous path


Original Image Binary Version of Restored Image


Slight differences are apparent if 4-point or 8-point connectivity is assumed


Problem with 8-point connectivity

Are voids or particles continuous at these points?

No problem with 4-point connectivity


Dynamic Studies: - deforming soils in SEM

Shear Box used in 1973 study


VIDEO of dynamic deformation

School of Environmental Sciences


A Study of Hong Kong Marine Soils

Simplified Sequence of Deposition

During last inter-glacial

deposition of unit M2

When sea level fell, surface layer was exposed to desiccation, oxidation, pedogenesis, etc.

In the Holocene, the sea probably covered the area around 6000 - 8000 years ago

deposition of unit M1

M1

T1

M2

~10m

Press Return to continue


Classification according to Yim (1994)

School of

Environmental Sciences

Freeze-dried example of recent Marine Soil (0.5m depth)


Bintang Bolon

The Gambia

School of


Open fabric preserved in Hong Kong Holocene deposit


School of


Fabric in M1 unit beneath Trial Embankment showing flow patterns around silt sized grains


School of


Aggregates of stacks of kaolinite particles showing evidence of cementation: Kwai Chung Container Terminal


School of


Deposition of amorphous material at base of M1 unit borehole T8.


School of


Schematic showing different changes in fabric from consolidation.


School of


Sand grains filling crack in palaeo-desiccated layer


School of


Pyrite within Hong Kong Marine Soil


School of


Sulphate reducing bacteria and framboid of pyrite in recent marine clay


Bintang Bolon: The Gambia

School of


Pyrite within a decaying root of mangrove: The pyrite appears to form away from the bacteria

Bintang Bolon: The Gambia


Pyrite in Chek Lap Kok marine clay also show concentration of nickel. Image analysis shows varying degrees of oxidation within the pyrite.


School of


Formation of halite crytals

Optical Micrograph showing halite crystal 100 m + in size in desiccation crack

Small halite crystals (1 - 5 m in size on side of root salt tolerant Mangrove


School of


Optical Micrograph of halite crystal and corresponding trace in BSE image


Procedure of segmentation is know as Mineral-Segmentation

5th Intensive Course on Soil Micromorphology - Naples 2001Image Analysis - Lecture 9: Multi-Spectral Methods

5th Intensive Course on Soil Micromorphology - Naples 2001Image Analysis - Lecture 9: Multi-Spectral Methods

Index of Anisotropy

outside aggregate: 0.229

inside aggregate: 0.374

In both cases the predominant orientation is nearly vertical.

Vertical direction in field.

• Image acquisition

•Image Processing• Image enhancement • Filtering• Image reconstruction

• Image Analysis

•Quantitative analysis

• Interpretation

The four I’s of Microfabric Analysis


5th Intensive Course on Soil Micromorphology Naples 2001 12th - 14th September Image Analysis...

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