NATIONAL UNIVERSITY OF SCIENCE AND TECHNOLOGY
FACULTY OF INDUSTRIAL TECHNOLOGY
DEPARTMENT OF CIVIL AND WATER ENGINEERING
GEOTECHNICAL ENGINEERING 1
TCW 3205
Assignment 1.1
Total Marks: 50
Time: 7 days
QUESTION 1
A 6-m-high retaining wall is to support a soil with unit weight 𝛾 =17.4 kN/m3, soil friction angle
𝜙 = 26° and cohesion 𝑐 =14.36 kN/m2. Determine the Rankine active force per unit length of the
wall both before and after the tensile crack occurs, and determine the line of action of the resultant
in both cases
(15 marks)
QUESTION 2
Given an element with stresses as indicated in the Fig., find:
a) The major and minor principal stresses and the planes on which they act
b) The stresses on a plane inclined at 30° from the horizontal
c) The maximum shear stress and the inclination of the plane on which it acts
(15 marks)
Page 1 of 2
Copyright: National University of Science and Technology, 2016
QUESTION 3
For the given failure surface, determine the factor of safety in terms of total stress for the slope
detailed in Fig. 2. The unit weight for both soils is 19 kN/m3. The characteristic undrained strength,
cu is 30 kN/m2 for
soil 1 and 45 kN/m2 for soil 2. What is the factor of safety if allowance is made for the development
of a tension crack?
(20 marks)
Fig. 2
Page 2 of 2
Copyright: National University of Science and Technology, 2016