What is the sinkhole/subsidence/ ground collapse mechanism under a leaking sewer pipeline in a non-krast urban area (areas with no carbonate rocks or lime stone)?
Because sinkhole also use to occur in areas with no carbonate rocks or lime?
So how both sinkholes are different when it comes to mechanism?
1) Sinkholes which occurs in areas with carbonate rocks?
2) Sinkholes which occurs in areas with no carbonate rocks?
Well, look like the mechanism in the attached pdf, but differ in the source.
Article Geomechanical modelling of sinkhole development using distin...
Regards
@Bayan Hussien thank you for sharing the Article. I will give it a look.
H.Ali
Sinkholes in carbonate rocks occur as a result of the collapse of the roof of karstic forms which develop due to the dissolution of CaCO3 in limestones or other carbonate rocks. So this is the main mechanism.
In the case of underground pipelines in urban areas these are usually placed in excavated trenches and embedded in aggregate or soil-aggregate materials compacted according to technical specifications. When a leak occurs then the underlying aggregate or soil material is gradually washed away due to the erosion and even embankments or other engineered soil can be transported by the piping of the leaking water. Thus small or larger cavities can be formed under the infrastructure (usually road pavement etc) and consequently collapse.
I hope that this points out the different mechanisms.
Thomas Makedon ! Thank you So much. It was very helpful to understand the difference.
Regarding the leaking pipelines i have another query. Firstly, If the pipe is leaking continuously from pipe and Secondly, if the pipe is leaking non-continuously (cyclic). In which case the settlement/collapse is more/earlier and Why? Or it will remain same for both conditions?
If you have any references for this it will be appreciated.
Thank you in advance
Ali
Settlement will only occur if the original soil underneath the pipelines contains a significant percentage of clay in which case the saturation could cause further consolidation.
The rate of leaking (continuous or not) in my opinion is not as important as the velocity of the flow which is related to the permeability and affects the capacity of water to erode and transport the aggregate or soil grains.The higher the velocity the higher the probability of the water washing out the material around or under the pipeline. The materials used in such cases are usually coarse grained with little or no percentage of fines therefore their permeability in cases of poor compaction is high. Darcy's law describes the flow discharge in relation to the hydraulic gradient and soil permeability.
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