A temporary earth retaining wall consists of wooden plank driven vertically into the ground. The wall is designed to resist 2.4 m height of soil.
Cross-sectional dimensions of the plank = 300 mm wide × 75 mm thick
Allowable bending stress of the plank = 10.4 MPa
Allowable shear stress of the plank = 0.8 MPa
Unit weight of retained soil = 17.3 kN/m3
Active earth pressure coefficient = 1/3
1. Calculate the maximum flexural stress.
|A. 12.7 MPa
||C. 8.6 MPa
|B. 14.2 MPa
||D. 10.1 MPa
2. Calculate the maximum shear stress.
|A. 1.11 MPa
||C. 0.99 MPa
|B. 0.33 MPa
||D. 0.77 MPa
3. Calculate the minimum thickness of the plank to prevent failure.
|A. 90 mm
||C. 110 mm
|B. 80 mm
||D. 100 mm