DIRE DAWA UNIVERSITY
INSTITUTE OF TECHNOLOGY
SCHOOL OF CIVIL ENGINEERING AND ARCHITECTURE
DEPARTMENT OF CIVIL ENGINEERING
COURSE TITLE: GEOTECHNICAL ENGINEERING DESIGN II
GROUP ASSIGNMENT
TARGETED GROUP: 5TH YEAR 1ST SEMESTER
GROUP 1 MEMBERS NAME & ID NUMBE
1. GADISA GEDA …………………………….. ....................... 1200400
2.ABENEZER ERMEKO ………………………………………........ 1201797
3.G/KIDAN BEFKADU ……………………………………............. 1204146
4.YOHANNIS DESALEGN ……………………………………....... 1201579
SUBMITTED TO: INST. MIKIYAS D.
SUBMISSION DATE: JANUARY, 2024 G.C
DIRE DAWA, ETHIOPIA
, Work out (show your step clearly) each question carries equal marks
1. The cross section of the cantilever retaining wall shown below. Calculate the factor of
safety with respect to overturning, sliding and bearing capacity.
γc (Unit weight of concrete)= 24KN/M3
0.5m H1
10°
6m
1
D = 1.5m 2
0.7m
C
0.7 0.7 2.6m 3
γ1 = 18 KN/M3 γ2 = 19 KN/M3
ɸ1 = 30° ɸ2 = 24°
C1 = 0.0 C2 = 40 KN/M2
Solution
By using Rankines Theory
The first thing is to determine the active force per unit length of the wall
1
Pa = * γ1 * HT2 * Ka
2
H1 = tan θ*2.6m = tan 10°*2.6m = 0.458m
HT = H1 + H2 + H3 = 0.458 + 6m + 0.7m = 7.158m
For inclined back fill
Ka = 0.350 From table 14.2 by using α = 10° and ɸ1 = 30°
Or Ka = cosα cosα − √ ¿ ¿ ¿
1
Pa = (18) (7.158)2 (0.350) = 161.40 KN/M
2
Ph = Pa *cosα = 161.4 * cos10° = 158.95 KN/M
Pv = Pa *sinα = 161.4 * sin10° = 28.03 KN/M
We will neglect the passive pressure, that is only for additional of factor of safety.
Factor of Safety Against Overturning
ƩMR
Factor of Safety overturning = ¿2
ƩMo
1
INSTITUTE OF TECHNOLOGY
SCHOOL OF CIVIL ENGINEERING AND ARCHITECTURE
DEPARTMENT OF CIVIL ENGINEERING
COURSE TITLE: GEOTECHNICAL ENGINEERING DESIGN II
GROUP ASSIGNMENT
TARGETED GROUP: 5TH YEAR 1ST SEMESTER
GROUP 1 MEMBERS NAME & ID NUMBE
1. GADISA GEDA …………………………….. ....................... 1200400
2.ABENEZER ERMEKO ………………………………………........ 1201797
3.G/KIDAN BEFKADU ……………………………………............. 1204146
4.YOHANNIS DESALEGN ……………………………………....... 1201579
SUBMITTED TO: INST. MIKIYAS D.
SUBMISSION DATE: JANUARY, 2024 G.C
DIRE DAWA, ETHIOPIA
, Work out (show your step clearly) each question carries equal marks
1. The cross section of the cantilever retaining wall shown below. Calculate the factor of
safety with respect to overturning, sliding and bearing capacity.
γc (Unit weight of concrete)= 24KN/M3
0.5m H1
10°
6m
1
D = 1.5m 2
0.7m
C
0.7 0.7 2.6m 3
γ1 = 18 KN/M3 γ2 = 19 KN/M3
ɸ1 = 30° ɸ2 = 24°
C1 = 0.0 C2 = 40 KN/M2
Solution
By using Rankines Theory
The first thing is to determine the active force per unit length of the wall
1
Pa = * γ1 * HT2 * Ka
2
H1 = tan θ*2.6m = tan 10°*2.6m = 0.458m
HT = H1 + H2 + H3 = 0.458 + 6m + 0.7m = 7.158m
For inclined back fill
Ka = 0.350 From table 14.2 by using α = 10° and ɸ1 = 30°
Or Ka = cosα cosα − √ ¿ ¿ ¿
1
Pa = (18) (7.158)2 (0.350) = 161.40 KN/M
2
Ph = Pa *cosα = 161.4 * cos10° = 158.95 KN/M
Pv = Pa *sinα = 161.4 * sin10° = 28.03 KN/M
We will neglect the passive pressure, that is only for additional of factor of safety.
Factor of Safety Against Overturning
ƩMR
Factor of Safety overturning = ¿2
ƩMo
1
