2.4.1 Introduction to Direct Shear Testing2.4.2 Direct Shear Rotation of Principle Stresses2.4.3 Use of the Direct Shear Test to Determine Internal Friction Angle, ϕ2.4.4 The Direct Shear Test – Details2.4.5 How Can the Direct Shear Test Go Wrong?2.4.6 Evaluating Results of Direct Shear Tests2.4.7 Concluding Remarks about the Direct Shear Test