Stability of River Dike: Study of Compacted Soils at Very Low Stress
River dikes are an elongated natural occurring ridge or artificially constructed fill or wall, which regulates water levels. It is often earthen and often parallel to the course river in its flood plain or along low line coast lines. The main purpose of the artificial dikes are to prevent flooding of the adjoining countryside and to show natural course changes in a waterway to provide reliable shipping lanes for maritime commerce over time; they also confine the flow of river resulting in higher and faster water flow.
From the slope stability point of view of such dike, effective strength parameters give the most realistic solution, particularly with respect to the position of the critical slip surface. However, well defined failures envelop in the low stress range and an accurate estimate of the true cohesion is essential when the stability of soil layer subjected to low consolidation stresses is considered. For typical geotechnical engineering practice, the failure envelop is extended linearly to the stress range and the cohesion intercept is assumed to be zero for normally consolidated soil which is disputed very much in stability analysis. Researcher believe the failure envelop to be curved towards zero in the low stress range.
• To study the shear strength behavior and deformation characteristics of river dike soil (mixture of clay, silt, and sand) at very low stress using direct shear test and triaxial compression test.
• To draw the well defined failure envelop and estimate the true cohesion and friction angle at very low stress.
• To check the validity of failure envelop which is extended linearly to low stress range and assumed cohesion intercept to be zero.
• Assessments of river dikes against flood infiltration using circular slip circle method combined with pore water pressure analysis and check the disputed true cohesion treatment on stability analysis in low stress range.
Experimental study will be carried out to understand the shear strength behavior and deformation characteristics of soil at very low stresses. The following test will be conducted in our lab:
1) Direct Shear Text
2) Triaxial Compression Test
Direct Shear Test: It is a very simple test used to measure the shear strength properties of soil. A confining stress is applied vertically to the specimen and shear stress horizontally.
• The shear box is made of two separate halves (upper and lower).
• After the application of a normal load, these two halves are moved relative to one another, shearing the soil specimen on the plane that is the separation of the two halves
• The direct shear test imposes stress conditions on the soil that force the failure plane to occur on the plane that separates the two halves of the box
• On this plane there are two stresses acting - a normal stress, σ n, due to an applied vertical load and a shearing stress,...