5. Conclusion
In this study, a new simple theoretical model was developed based on
Bernoulli’s principle to understand the erosion process in the hole
erosion test (HET). The constitutive equation of erosion characteristics
was further developed into a differential equation to find out the
dynamic prediction model of erosion process. It was found that eroded
hole radius as a function of time (\(R\left(t\right)\)) followed the
power function with an exponent of 0.25. Based on the known\(R\left(t\right)\), other physical quantities namely erosion rate,
pressure drop, and erosion characteristics can be deduced. Besides, a
new equation was proposed to determine the erosion coefficient by
observing the realistic change of hole radius (soil loss). The model was
validated with HETs for various flow conditions. Model performance was
also evaluated based on tests conducted in the literature. These was
reasonably good agreement between measured and predicted erosion
characteristics (from newly developed model) under different hydraulic
conditions. Furthermore, the reported phenomenon of HETs in the
literature was considerably interpreted by proposed equations. The
interpreted experimental results suggested that erosion coefficient
marginally increased during the entire process of internal erosion in
HET. Three distinct phases (i.e. initial, normal, and final phases) were
used to explain the internal erosion process in HET. The advantage of
the proposed model is that the erosion characteristics are determined by
considering the realistic measured change in radius of the soil hole.
The proposed formulation in this study was tested only for HETs.
However, further studies are needed to understand its applicability for
determining the internal erosion in various geotechnical infrastructures
in the field.