Description
Hello ,,
this is my Geotechnology assignment, please read carefully, its so important
you have to do it based on these information:
**Cousre grained soul bulk unit weight :18 kn/m3
Course grained soil friction angle :45 degress
Clay soil saturated cohesion : 90 Kpa
Unformatted Attachment Preview
Purchase answer to see full attachment
Explanation & Answer
Attached.
Structural Analysis and Design
ANALYSIS AND DESIGN OF GEOTECHNICAL STRUCTURES
By Student Name and ID
Geotechnology 2 (CIVL 0016)
Professor’s Name
Middle Eat College
Department of Civil Engineering
FALL 2019
Date
1
Structural Analysis and Design
2
TABLE OF CONTENTS
INTRODUCTION .......................................................................................................................... 3
MATERIALS, METHODS OF ANALYSIS AND RESULTS ..................................................... 4
DISCUSSION ................................................................................................................................. 4
Analysis and Design of a Cantilever Retaining Wall ............................................................. 4
Design Parameters ................................................................................................................. 4
Approximate Proportions ..................................................................................................... 5
Checking for Sliding .............................................................................................................. 6
Overturning ............................................................................................................................... 6
Ground bearing pressure ...................................................................................................... 7
Stem Design ............................................................................................................................ 8
Base/Heel Design .................................................................................................................... 8
Rectangular Pad Footing Design and Analysis....................................................................... 9
Loading ................................................................................................................................. 10
Bending Reinforcement ....................................................................................................... 10
Ultimate Moment ................................................................................................................. 11
Main steel.............................................................................................................................. 12
Punching Shear .................................................................................................................... 12
Face Shear ............................................................................................................................ 13
Transverse Shear ................................................................................................................. 13
Design Philosophy of Earthen Dams ..................................................................................... 14
Introduction ......................................................................................................................... 14
Design Aspects...................................................................................................................... 15
Seepage Analysis .................................................................................................................. 15
Seepage Management .......................................................................................................... 16
Load Carrying Capacity of a Group Pile .............................................................................. 17
Ultimate bearing capacity for pile with square cross-section .......................................... 17
Ultimate bearing capacity for pile with circular cross-section ........................................ 18
CONCLUSION ........................................................................................................................... 19
References ..................................................................................................................................... 20
Structural Analysis and Design
3
INTRODUCTION
Geotechnical structures are important engineering structures since they are designed
using scientific methods, simulation and approaches to ensure that end results have features that
ensure safety of those using the structures as well as the health. These structures also offer the
required service for an extended period, that is, they can fiction for many years; hence, they are
sustainable. Examples of these geotechnical structures include but are not limited to retaining
walls, building foundations, bridges, tower, and earth dams, among other structures.
Geotechnical engineers use different scientific approaches and methods to evaluate
materials and conditions of the soil in different environments while applying the principles of
mechanics of rocks and soil to offer solutions to problems related to these structures by
analyzing and designs structures that suit particular purposes. Conditions considered for
sustainability, safety of retaining wall meant for retaining back fill along a road might differ from
those considered for the construction of retaining all meant for landscaping and beauty.
Geotechnical properties of the soil and rock material such as compaction, permeability, cohesion,
seepage are analyzed in lab or field before considering design of structures (Roy & Bhalla 2017).
This report aimed to provide an experience to the analysis and design of geotechnical
structures, that is, cantilever retaining wall, a pad foundation, a group pile and earthen dams,
with the focus and emphasis on safety and sustainability needs. Interpretation of design output
was also part of this report’s objectives. This report is crucial in the Geotechnology 2, CIVL
0016 module because it gives me an opportunity to exploit my ability to design geotechnical
structures that form a solution to a specific engineering problem. It is a good evaluator and a way
of improving my understanding of the class concepts learned.
Structural Analysis and Design
4
MATERIALS, METHODS OF ANALYSIS AND RESULTS
The structural design of a retaining wall involved providing the size of steel
reinforcements that can withstand all the horizontal and vertical forces acting on the wall.
Necessary checks for safety were also computed and include failure due to shear, overturning
and sliding. In designing a rectangular pad footing, the load factor method was used in the entire
process to determine design parameters. The given loads were multiplied by various factors of
safety for both dead loads and live and variable loads to obtain design loads. The design of the
rectangular pad footing involved determining the pad footing plan area with the use of
serviceability loads while considering in design assumptions. Reinforcement areas necessary for
bending were determined using the ultimate loads calculated. The designed rectangular pad
footing was checked for punching shear, transverse, and face shear failures. Evaluating the effect
of shape on the load carrying capacity of a group pile utilized the static method that involved
determine nation of the bearing resistance and the skin friction resistance capacity of the group
piles. Both of these forces were determined using empirical models and mathematical formulas.
DISCUSSION
Analysis and Design of a Cantilever Retaining Wall
Design Parameters
Unit weight of soil, 𝛾𝑠 =18kN/m3
Surcharge, 𝜔==15kN/m2
Height of surcharge, h =3+0.3=3.3m
Height of wall, H=3.0m
fck=30N/mm2
Structural Analysis and Design
fyk=500N/mm2
Assumed concrete cover= 75mm
Approximate Proportions
Base width, L=2.3m
Base thickness, D=0.10H; H=0.3/0.1= 3m
Stem thickness at the bottom, C=0.10H=0.10*3=0.3m
L=2.0 + 0.3=2.3m
1−sin ∅ 1−sin 45
Ka=
=
= 0.172
1+sin ∅ 1+sin 45
Active pressure= ka𝛾sh =0.172*18*3.3=10.22kN/m2
5
Structural Analysis and Design
Checking for Sliding
Considering forces acting on 1m length wall
Horizontal force due to back fill=1/2* ka𝛾sh2=1/2*0.172*18*3.32=16.86kN
Force due to surcharge=𝜔kah=15*0.172*3.3=8.514kN
Total active horizontal force= 8.514 +16.86= 25.374kN
Assume passive pressure, pp=0
Weight of wall, Ww=0.3*3.0*1*24=21.6kN
Weight of base, Wb=2.3*0.3*1*24= 16.56kN
Weight of surcharge, W𝜔=15*2*1=30Kn
Total resisting or vertical force=176.16kN
Assuming friction factor of 0.4, friction force= 0.4*176.16=70.464kN
𝑅𝐹 70.464
=
= 2.78 > 1.5 (OK), that is, it is safe from sliding
𝑆𝐹 25.374
Overturning
Taking moments about point A;
Overturning moment, OM=H/3*FA + ½*Fω= 1/3*3.3*16.86 + ½*3.3*8.514= 32.5941kNm
Restoring moments, RM=Ws*1.3 + Ww*0.15 + Wω*1.3 + Wb*1.15=
= 108*1.3 + 21.6*0.15 + 30*1.3 + 16.56*1.15=201.684kNm
=201.684kNm
6
Structural Analysis and Design
𝑅𝑀
201.684
Factor of safety against overturning=𝑂𝑀 = 32.59141= 6.19 < 2.0
(OK) hence structure is safe
from overturning.
Ground bearing pressure
Taking a 1m strip of footing
R. F or P=176.16Kn; A= 2.3*1= 2.3 m2
OM (M)= 32.5941; d=2.3m; L=1m;
𝑃
6𝑀
Maximum soil bearing capacity, qmax=𝐴 + 𝑏𝑑2 < qall =
176.16
2.3
(allowable), hence OK!
Ultimate bearing pressure;
Nominal moment, Mn=32.5941;
Ultimate moment, Mu=1.6Mn=1.6*32.5941=52.15056kNm
b=1m; d=2.3m
A=2.3*1 =2.3m2
P=1.6Ws + 1.4Wb + 1.4Ww + 1.6W𝜔
= 1.6*108 + 1.4*16.56 + 1.4*21.6 + 1.6*30= 274.224kN
𝑃
6𝑀
qu=𝐴 ± 𝑏𝑑2 =
274.224
2.3
qumin= 60.08kN
qumax=178.38kN
±
6∗52.15056
2.32
+
6∗32.5941
1∗2.32
= 113.56kPa ≤ 120 kPa
7
Structural Analysis and Design
M=32.5941; N= 176
M/N=32.5941/176.16=0.185m < d/6=2.3/6=0.38
Stem Design
Stem height=3m
Horizontal force due to back fill on the stem= ½*ka*𝛾s*hs2= ½*0.172*18*32= 13.932 kN/m
width
Design moment at the base of the wall, Ml=
𝑟𝑓 ∗𝐹�...