In the analysis of geohazards, one of the most common techniques used is laboratory soil testing. This is where a sample of soil is taken from the area in question and analysed in a laboratory to see if any risk of geohazard activity can be indicated by its condition.
Some of the measures analysed in laboratory soil testing include particle size (the size of each part of the soil), plasticity (how malleable each particle is) and compaction (the density of the soil sample). These factors, along with many others assessed through other techniques in the lab, help show the geotechnical engineers whether the soil composition means that an area is at risk of certain geohazards, helping that area’s community prepare through a series of carefully planned strategies.
Soil testing not only helps engineers to determine the properties of the soil, but also the rocks beneath, which can point towards potentially widespread risks of geohazards, and tests can be made on surface and sub-surface soils. Many of the analysis techniques involve checking how much water the soil can hold, which can play a major role in the way geohazards pan out.
Various different techniques are used to prepare the soil for testing, including breaking up the sample to allow the heat from oven drying to permeate evenly through the soil, and removing organic matter such as tree roots and leaves, which might skew the results and lead to inaccuracies in the results. Water may then be deliberately added to the sample to find out its water-bearing threshold, which can tell the engineers a lot about the way the land on site will react to certain geohazards.
Getting a soil sample from your local area tested in a lab is extremely useful as it can tell you a lot about risks you may not have considered. Sub-surface soil testing in particular can provide indicators of previous geohazard activity in the area. You will receive a comprehensive set of results detailing exactly what the tests show about the soil composition in the area, and with the help of the geohazard engineers, you can create a damage limitation strategy. For instance, soil which isn’t very absorbent may mean that water run-off can be a risk, leading to water damage to properties and infrastructure.
Obviously it’s unlikely that anyone will have all the necessary equipment lying around to perform a soil analysis themselves, and even less likely that they will then have the know-how to carry out the tests and understand the implications of the results, so laboratory soil testing really does need to be carried out by professionals if it’s going to tell you anything useful about the risks in your area.
Benjamin Earl is a geotechnical engineering student currently blogging for Fugro Geoconsulting
