Stress-strain behavior of soils having undergone different amounts of internal erosion

Results of an experimental investigation are reported, conducted to study the stress-strain behavior of a soil having undergone different amounts of internal erosion. The soil used is gap-graded and cohesionless comprising silt, sand and gravel. Internal erosion tests and subsequent triaxial tests are performed in a specially designed apparatus having modified perforated end platens and a drainage system that permitted the erosion to occur. A constant water head tank is used to drive the erosion and an effluent collection system is used to observe the eroded material. Different amounts of erosion, which progressively narrow the soil grading while maintaining a constant confining stresses, are caused by passing water through compacted soil samples inside the triaxial apparatus in an upward or downward direction. Flow rate through, settlement and volume change of the samples are monitored during the erosion. After erosion, drained compression tests are conducted. Another drained compression test is also conducted on a sample that has not eroded for comparison. It is observed that drained peak deviator stresses progressively reduce and the volumetric deformation of samples become less dilative with increasing amounts of erosion.