Question

Field monitoring equipment has been installed on a slope where there is a concern of potential failure. The maximum shear stress in the field is recorded at 167 kPa. Lab testing on the same soil has indicated the shear strength at failure is 150 kPa. Based on this information, what are your thoughts regarding the potential for slope failure in the field?

Answer 1

Soil is always fail in shear.

Shear strength at failure  = 150 kPa

Maximum shear stress = 167 kPa

Maximum shear stress is always more than the shear strength at failure. It does not mean soil will fail.

Soil will fail if shear strength of soil is less than shear stres in soil at failure. As shown in above figure maximum shear stress is at the top of mohr circle and shear strength at = 150 kPa

Hence we can say soil is not fail in this case .

comment for any doubt about this solution thank you

Don't forget to upvote if you got your answer