SOIL LIQUEFACTION

When Greet and I returned to Warmbaths from the Eastern Cape, after honeymooning with Bruce and Joey Barichievy, I got stuck into modifying the front end of my Landrover. I used angle-iron and galvanised sheeting and pop-rivets. I had no welder or grinder, so it was all shaped, drilled and cut by hand. Then I painted the vehicle cream with a red stripe up the bonnet; all with a paintbrush, so it was a very amateur job, but it was an eye-catcher. Is it a bird, is it a plane?

Is it a bird?

Is it a bird?

As usual, the field technicians of Loxton, Venn & Associates were unable to return to Mozambique due to the seasonal flooding, which was particularly severe in ’73/’74. I do not recall where anyone else was sent to, but my job was to take soil samples of an area near Vereeniging, Southern Transvaal, that was earmarked as an extension to the town. A recent law that no go-ahead would be given without a soil survey found me taking samples on old farmland, living in a caravan. I was issued with a Land Rover fitted with an engine-driven auger mounted on the back. It had one metre long extensions and could bring up samples from just over two and a half metres.

The soil was medium textured red clay. Drilling into it in one section, I was astounded to see the clay turn to mud. I had never heard of such a thing.

Apparently, it is called soil liquefaction. Sometimes called earthquake liquefaction, otherwise solid soil is caused to behave temporarily as a viscous liquid. The phenomenon is usually supposed to occur in water-saturated, unconsolidated soils affected by seismicS waves (secondary waves), which cause ground vibrations during earthquakes. Although earthquake shock is the best known cause of liquefaction, certain construction practices, including blasting and soil compaction can produce this phenomenon intentionally. I understand that poorly drained fine-grained soils such as sandy, silty, and gravelly soils are the most susceptible to liquefaction, but in this case, the water seemed to be locked up in the cubic structure of the clay, which broke down when the auger was driven into the earth. Perhaps the vibration of the tool was similar to that produced by earthquakes?

Naturally, my report described this phenomenon, but I was never given any feedback as to whether the area was subsequently built up, or not. However, I’m sure that by this time, nearly forty years later, it has been covered in urban sprawl, legal or otherwise.

About peterjearle

Writer of thriller novels. 4 Published: 'Purgatory Road', 'The Barros Pawns', and the Detective Dice Modise Series:'Hunter's Venom' and 'Medicinal Purposed Only', all from Southern Africa.
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One Response to SOIL LIQUEFACTION

  1. Jane Risdon says:

    I know all about liquefaction, having survived the LA quake in 1993….talk about shake rattle and roll! I found this really interesting. Thanks for sharing. Will you ever return? Thanks for liking my blog too…appreciated. 🙂

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