Date of Award:


Document Type:


Degree Name:

Master of Science (MS)


Civil and Environmental Engineering

Committee Chair(s)

John D. Rice


John D. Rice


James A. Bay


Marc Maguire


Backward erosion piping is a type of internal erosion. It occurs beneath water structures as a result of seepage force. It needs two conditions to take place; 1) sufficient hydraulic head to drive the seepage force, and 2) cohesive layer overlies the sand layer and this will lead to concentration of flow. Many researches were done in the past in an attempt to predict the critical gradient. But it was just taking into account the buoyant unit weight which found in recent research that piping can occur at much lower values than was predicted. And other researches were too conservative for predicting critical hydraulic gradient.

The objectives of the research are to help better understanding the mechanism of failure during backward erosion piping and to investigate the factors affecting the average critical gradient. A physical model was developed at Utah State University to simulate this problem. Different types of soils with a wide range of gradation, unit weight, and specific gravity were used with different diameter of outlets to provide a good results of backward erosion piping process. This can help to improve more practical ways for predicting and preventing this type of erosion. This research can lead to further studies with different scales of models and soil types for better predicting of backward erosion piping and trying to develop more efficient methods. This will increase the public safety in terms of improve the design of earth structure such as levees and dams and helps the efforts to avoid such failures similar to which happened in the past.