GEO 4023
Engineering Geology
Homework 5
Due Wednesday 4 November 2020
Name__________________________________
1. (20 pts) For a fractured rock layer on a slope, determine whether the following scenarios are
stable or unstable:
(a) Slope = 30o
h = 40 ft
b = 20 ft
(b) Slope = 35o
h=25 ft
b=12 ft
(c) Slope = 35o
h = 35 ft
b = 25 ft
(d) Slope = 25o
h = 7 ft
b = 4 ft
2. (20 pts) Assuming a translational-type slide, determine if the following slope is stable or
unstable:
= 32o
h=40 ft
Soil Volume = 1500 ft3
Soil specific weight = 145 lb/ft3
Soil failure envelope:
τ = 100 + σ tan 25o lb/ft2
Block thickness = 1 ft
GEO 4023
Engineering Geology
Homework 5
3. (20 pts) Assuming a translational-type slide, determine if the following slope is stable or
unstable:
= 22o
h=50 ft
Soil Volume = 1000 ft3
Soil specific weight = 115 lb/ft3
Soil failure envelope:
τ = 120 + σ tan 30o lb/ft2
Block thickness = 1 ft
4. (20 pts) Assuming a rotational-type slide, determine if the following slope is stable or
unstable:
ψ = 90o
Soil Volume = 1850 ft3
Soil specific weight = 125 lb/ft3
R = 25 ft
x = 15 ft
Soil failure envelope:
Block thickness = 1 ft
τ = 175 + σ tan 29o lb/ft2
GEO 4023
Engineering Geology
Homework 5
5. (20 pts) Assuming a rotational-type slide, determine if the following slope is stable or
unstable:
ψ = 70o
Soil Volume = 1200 ft3
Soil specific weight = 108 lb/ft3
R = 30 ft
x = 10 ft
Soil failure envelope:
Block thickness = 1 ft
τ = 130 + σ tan 36o lb/ft2