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CE 616: Earth Retaining Structures
M.Tech Geotechnical Engineering.
A case study on geotechnical design
Dr. Ramakrishna Bag
[email protected]
Dept. of Civil Engineering
National Institute of Technology, Rourkela
mailto:[email protected]
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PROPOSED HIGHWAY CONSTRUCTION
Design 1km stretch of a highway in a rural area, encompassing
a
crossing with an existing rural road on a flat low lying flood
plain.
Design aspects should consider the following:
A minimum gradient of 1:300 is required to meet surface
water
runoff requirements.
The 10 year return period flood level is 52 m.
Earth retaining embankments are to be constructed to a
gradient
of 1:2 due to limited land availability.
A minimum clearance is required between road level and the
underneath of a bridge. The clearance for each group should
be
as given in the Table:
Group no. Minimum clearance (m)
1 4.5
2 5.0
3 5.5
4 6.0
Width of existing rural road is 5m and width of highway is
20m.
Existing rural road and highway should not meet at the same
level. There may be a separate connecting road between
highway and rural road.
There should not any sharing of calculations between
different
groups.
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Every individual must submit their report latest by 17th
April,
2015; 17:00 hours through moodle.
Only calculations will be shared amongst group members.
Copying from other will lead to penalty for both students.
The report must include Summary, Introduction, Design
solution, Conclusion and Appendix. Except Appendix every
individual must write on their own.
Appendices will be group submission containing settlement,
bearing capacity and slope stability calculation.
The group members will be as follows
BAISHNU BHUSAN BEHERA
Gr 1 VIKAS KUMAR
ABHISHEK KUMAR
SHWETA YOGIRAJ MAHAJAN
PIYUSH PARIK
Gr 2 AHSAN RABBANI KARNATI CHAKRAPAN
PADMAJA SWAIN
ANOOP KUMAR TIWARI
Gr 3 BANAVATH RAMESH
RANAJEET MOHANTY
TARINI JAHNAVI
JYOTIRMAYEE MALLICK
Gr 4 RAMANA REDDY KATIPELLY
DUMMU SINDHUJA
SHUBHAM RAJPUT
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Site Plan
Distance between Point A and B is 1000 m.
Point A G.L. = 49.6 m
Point B G.L. = 50.5 m
Point C G.L. = 49.5 m
Point D G.L. = 50.2 m
Proposed highway
Existing rural Road
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Soil profile of borehole @ C/L of motorway as follows:
Vane shear test results
0
4
8
12
16
20
0 5 10 15 20
Dep
th b
elo
w G
.L (
m)
Shear strength (kPa)
150 mm Top soil
Very soft Clay of high
plasticity to soft brown clay
of high plasticity at depth
Brownish mud stone
0.15 m
0
18 m
20 m
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Properties of the soil and backfill material as follows:
Assume saturated soil
Properties Clay Fill material
Unit weight (kN/ m3) 18 (sat) 20
LL (%) 58 --
PL (%) 28 --
PI (%) 30 --
Friction angle, () 23o 35o
Effective cohesion, C (kN/m2) 2 20
Undrained shear strength,
Cu (kN/m2)
Look at vane
shear test results
73
The ultimate bearing capacity of the foundation soil (saturated
clay) can
be calculated from, qu = 7.5 Cu, where Cu is the undrained shear
strength
of soil.
Parameters for calculating total settlement and time required
for
settlement
Consider 70% time dependent consolidation settlement will take
place
during the construction period; mv = 0.004 m2/kN, cv = 1.8 m
2/yr.
