SOME ENGINEERING GEOLOGICAL

ADVANTAGES FOR DEVELOPMENT OF

UNDERGROUND TRANSPORTATION

SYSTEM FOR DHAKA CITY

May, 2005

MIR FAZLUL KARIM

Geological Survey of Bangladesh

(Following request from Louis Berger Group, Inc. and Bangladesh Consulting Ltd

This presentation was made for Strategic Transportation Planning Project of the

Government of Bangladesh)

E-mail- azadkk@gmail.com and mfk@agni.com

THE DATABASE OF THIS PRESENTATION IS

FROM DIFFERENT GEOLOGICAL

INVESTIGATIONS DONE BY THE GEOLOGICAL

SURVEY OF BANTGLADESH AND THE PAPER IS

PREPARED TO PROVIDE SOME CONCEP ON THE

GEOLOGY OF DHAKA CITY AND

ENGINEERING GEOLOGICAL ADVANTAGES AND

DISADVANTAGES FOR PLANNING, DESIGNING

AND DEVELOPMENT OF UNDERGROUND

TRANSPORTATION SYSTEM FOR THE MEGACITY

OF DHAKA

Geologically the City of Dhaka is developed

on Madhupur Terrace. The elevation the

terrace is 6 meter Above Mean Sea Level. It

is about 3 meter higher than the surrounding

flood plains. The terrace is formed of Older

Sediments and the surrounding floodplains

are formed of very young Alluvial deposits.

The issues confronting urban tunneling are not “can

tunnel technically be done?” but rather “what

are the advantages and disadvantages of

adopting one tunneling technique over another

and the consequences of the decision?”

The consequences concern are… 1. Public and political aspects

2. Cost and source of funding

3. Alignment

4. Geological and Hydro-Geological condition,

Risk Assessment and Ground Condition

Geological and Hydro-Geological condition,

Risk Assessment and Ground Condition

AS THESE ARE THE BASIC STUDY ELEMENTS

THAT WILL AFFECT

EXCAVATION, RETENTION OF THE OPENING OF

TUNNEL. GROUND IPROVEMENT AND OTHER

STRUCTURES ON THE SURFACE

THE OBJECTIVE IS TO UNDERSTAND THE

BEHAVIOUR OF SUBSURACE GEOLOGICAL

MATERIALS SUCH AS ROCK MASSES AND SOILS,

WATER, GASES, TEMERATURE, EARTHQUAKE ETC.

Geological and Hydro-Geological condition,

Risk Assessment and Ground Condition

•Topography for Elevation Control

•Surface Geology and Geomorphology

•Subsurface Geological Structure

•Stratigraphic Boundary conditions: Vertical and

Lateral

•Geo-Engineering Characteristics of Sediments

•Surface Water and Runoff Characteristics

Dhaka City

Elevation Map

Dark areas are prone

to annual flooding.

URBAN SETTELEMENTS

Topography for Elevation Control and Understanding of

Surface flooding

SURFACE GEOLOGY

AND

GEOMORPHOLOGY

3D MODEL OF DHAKA

JOYDEVPUR BLOCK

MONOCLINAL

CLAY BED ON

SAND BRED

GEOLOGICAL

STRUCTURES

POSSIBLE

FAULT

GEOLOGICAL

STRUCTURES

RED SOIL

CENTRAL

DHAKA

YELLOWISH

BROWN SOIL

EASTERN

DHAKA

GREY SOIL

WESTERN

DHAKA

0 M

6 M AMSL

YELLOWISH BROWN

THICK SAND

GEOLOGY OF DHAKA CITY

TONGI

RAMNA

UTTERA

BASHABO

SURFACE GEOLOGY

OF OF DHAKA CITY

0 meter

5meter

- 5 meter

- 10 meter

TUNNEL HORIZONE

Hydro-Geological condition

The permanent Ground Water Level is

located about 70m below the surface and

the all Hydro-geological environment is

favorable for underground activities,

There are three distinct

geomorphologic units

1. Central high area: This unit is

an elongated tableland above

flood level that stretches from

south to north. The elevation is

7m above mean sea level

(AMSL).

2. Complex of low and high areas:

This unit consists of narrow

strips of benches or foot slopes,

rounded to elongated saddle of

central unit, narrow and shallow

erosion gullies and incised

valleys or abandoned channels.

3. Complex of low areas: It consists

of flood plains of the rivers

Burhiganga, Sitalkhya and

Meghna, which is annually

flooded. The unit is flat and the

elevation is below 2m AMSL.

TONGI

RAMNA

UTTERA

BASHABO

JOIDEBPUR

The Central high area forms the axial zone and extends

northward up to Gazipur and then further up. The Madhupur

Clay Formation is well exposed throughout the zone. The

average elevation is 7 meters above mean sea level. The

localities lying in this zone includes the region from the old

city part in the south, Tejgaon, Gulshan, Uttera, Tongi to

Gazipur. The average width is about 2.5 km.

THE PROOSED RAPID TRANSIT ROUTE IS

CONFINED WITH IN THE AXIAL PART OF DHAKA

TERRACE

Surface Water and Runoff Characteristics

The zone is drained by numerous large and long

streams, which were once connected with the

rivers flowing through the outskirts of the city.

Most of the long streams are deep enough to cut

through Madhupur Clay Formation. There are

number of depressions in this zone, mainly along

the abandoned streams.

THE PROOSED RAPID TRANSIT ROUTE IS

CONFINED WITH IN THE AXIAL PART OF

DHAKA TERRACE

This zone is rated as Class 1 type ground condition, it

is composed of very stiff to hard reddish brown Clay-

Silt (Madhupur Clay Formation), having good

engineering properties of the materials and considered

to produce less ground motion than the other two

zones. As the zone is composed of stable geological

materials, this will undergo elastic and plastic

deformation and will serve to dampen any seismic

motion and maintain some strength level. Most of the

area in this zone is stable and suitable for wide

engineering options for foundation design

consideration. State and suitability of underground

excavation and tunneling is highly suitable for

underground constructions.

Fm T Litho. w

%

d su,

kPa

Suitability

Madh

u-pur

Clay

6 m Stiff

Clay

-SILT

2

5

16 kN/m3

150 Highly

suitable

Dupi

Tila

Sand

>

90

m

Very

dense

Sand

<

20

>

16 kN/m3

>

30o

Excellent

for under-

ground

activity

State and suitability of underground excavation and

tunneling

WESTERN CUT SECTION

NORTH

TONGI RAMNA

UTTERA

BASHABO

MIRPUR

RED CLAY

SANDSTONE

CLAY

SILT

TONGI

RAMNA

UTTERA

BASHABO

MIRPUR

TONGI RAMNA

UTTERA BASHABO MIRPUR

CLAY

SANDSTONE

CLAY

CLAY -SILT

NORTH

TONGI

RAMNA

UTTERA

BASHABO

MIRPUR

THICK CLAY IN THE

SOUTH EAST AND

EASTERN PART OF

DHAKA

WHAT WE WILL ENCOUNTER IN DEFFERENT PARTS

OF DHAKA CITY

CLAY

SILT

SAND

CLAY

SAND

CLAY

SAND

CLAY

SILT

TYPE A A TYPE A B TYPE A C TYPE B TYPE C

UD

1

Light brown stiff Clayey

SILT with sand

Yellowish brown medium

dense silty SAND

Light brown dense silty

SAND

Light brown dense coarse

SAND little silt

Reddish brown, stiff to

very stiff sandy Clay-SILT

18 D-14 43

17 D-13

42

16

D12

35

15

14 D11

39

13

D10

30

12

11 D-9

25

10

D-8

26

9

8 D-7

7

7

D-6 9

6

D-5

21

5

D-4

18

4

D-3

14

3

D-2

12

2

D-1

10

1 SPT

m

UD

1

Reddish to yellowish brown, stiff to very

stiff, Clay-SILT little sand

Yellowish brown, very soft sandy SILT,

(FILL)

Yellowish brown, stiff to very stiff, highly

plastic, mottled Clay-SILT little sand

Layer Change at 2.70m

Light grey, very stiff, highly plastic, sandy

clayey SILT

Yellowish brown, very stiff, Clayey

SILT with sand

16.00 D-12 25

15.00

14.00

D-11 20

13.00

18

12.00 D-10

11.00

D-9 16

10.00

9.00 D-8 21

8.00

D-7 20

7.00

D-6 19

6.00

D-5 20

5.00

D-4 13

4.00

D-3 10

3.00

D-2 1

2.00

2

1.00

2024 Mass

Rapid Transit

System

Phasing

CLAY

SILT

SAND

5m

30m

0m

5m

30m

0m

Geological Material Type A:

750 m/sec > Vs > 350 m/sec. Quaternary (less than 1.8 million

years old) sands, sandstone and clay-stones or shale, some

Upper Tertiary (1.8 to 24 million years old) sandstones,

mudstones and siltstone, some Lower Tertiary (24 to 64

million years old) siltstone and sandstone.

Geological Material Type B:

350 m/sec > Vs > 200 m/sec. Quaternary clays, sands, gravel,

silts and mud. Significant amplification of shaking by these

materials is generally expected.

Geological Material Type C:

200 m/sec > Vs. Water-saturated recent floodplain sediments

and artificial fill. The strongest amplification of shaking due is

expected for this material.

D

ha

n

m

on

di

K

a

m

ra

gi

r

C

ha

r

Isl

a

m

pu

r

D

e

m

ra

R

a

m

na

B

as

ha

bo

M

ir

pu

r

K

af

ru

l

B

ar

id

ha

ra

Ut

te

ra

Ut

te

r

K

ha

n

6m

4m

2m

0m

- 2m

- 4m

- 6m

- 8m

- 10m

- 12m

- 14m

- 16m

DT - DUPITILA SANDSTONE

MC -

MADHUPUR

CLAY

RESIDUUM

DT

DT

MC

MC

MC

DT

THE OPTIONS

Schematic 3D- Box Diagram of Dhaka City showing the

vertical and lateral extent of Madhupur Clay Residuum

and Dupitila Sandstone Formation. Possibility of three

vertical locations for placement of Underground Railway

System, A. At surface – to be constructed by Cut and Fill

Method, B. Near Surface – to be constructed below the

existing roads by Tunnel Excavation, where maximum

depth of the roof of the tunnel would be 8m below the

existing road surface (+6m AMSL) of Kazi Nazrul Islam

Avenue and C. Deep Tunnel – at a depth of at least 15m

from the existing surface of Kazi Nazrul Islam Avenue.

CITY ENGINEERING

GEOLOGY

DISADVANTAGES GEOLOGICAL

ADVENTAGES

KOLKATA AND

BANGKOK

YOUNG DELTAIC

SEDIMENTS,

SOFT CLAY, SILT

AND SAND AND

PEAT AT NEAR

SURFACE

ONLY CHOICE - CUT

AND FILL AS NO

FIRM STRTUM AT A

CONSIDERABLE

DEPTH. HEAVY

DEWATERING

EASY FOR

EXCAVATION AND

EASY FOR

REMOVAL OF

WASTE

MANHATTAN

AND MANY

EUROPEAN

CITIES

HARD ROCK DIFFICULT TO

DRILL OR

EXCAVATE..

REMOVAL

DIFFICULT

REQUIRES LESS

PROTECTION

DURING

PREGRESION OF

TUNNEL

DHAKA TERRACE OF

SEDIMENTARY

ROCK OR STIFF

CLAY AND VERY

DENSE SAND

WILL REQUIER

MODERATE

PROTECTION TO

RETAIN TUNNELS

BEFOR RIMMING

FREEDOM OF

CHOICE FOR ANY

METHOD OF

TUNNELING AND

REMOVAL OF WSTE

MATERIALS

A COMPARISON WITH OTHER CITIES

GEOLOGICAL SURVEY OF BANGLADESH CONSIDERS DHAKA GROUND CONDITION TO BE THE BEST THAN ANY OTHER CITIES IN THE WORLD FOR UNDER GROUND

ACTIVITIES

THANK YOU azadkk@gmail.com