Significance of site investigation Significance of site investigation

and geotechnical characterization and geotechnical characterization

using Field methodsusing Field methods

Dr D Neelima Satyam

Assistant Professor

IIIT Hyderabad

“Virtually every structure is

supported on soils; whose which

are not, either fly, float or fall over”

Natural aggregates of mineral grains, loose or moderately

cohesive inorganic or organic in nature that have the

capacity of being separated by means of simple mechanical

processes.

� Structures are built with soil

Dams , embankment

�Structures are built in soil

Structural foundations – footings, piles, rafts, tunnels

SOIL :SOIL :

Geotechnical engineeringGeotechnical engineering

� A unique combination of science, experience, judgment and a

passion for understanding the uniqueness and variability of

ground conditions resulting from the forces of nature.

� It is the art of determining the properties of unseen and

variable materials to provide a facility that perform as

expected at acceptable level of risk and at an optional cost.

Foundation EngineeringFoundation Engineering

� In a broad sense, foundation engineering is a art of selecting,

designing and constructing the elements that transfer the weight of

structure to the underlying soil or rock.

� The role of engineer is to select the type of foundation, its design

and supervision of construction.

Before the engineer can design a foundation intelligently, he must

have a reasonably accurate conception of the physical properties

and the arrangement of the underlying materials. This requires

detailed soil explorations.

General ObservationGeneral Observation

1. Soil does not posses a unique or linear stress-strain relationship.

2. Soil behavior depends up on the pressure, time and environment.

3. Soil at every location is essentially different

4. Nearly in all the cases, the mass of soil involved is underground and cannot be seen entirely, but must be evaluated on the basis of small size samples, obtained from isolated locations.

5. Most soils are very sensitive to disturbance from sampling and thus the behavior measured by a lab test may be unlike that of in situ soil.

The lowest part of a structure is generally referred to as foundation.

Definition of foundationDefinition of foundation

To transfer load of the superstructure to the soil on which it is

resting.

Function of foundationFunction of foundation

A properly designed foundation is one that transfers the structural

load throughout the soil without overstressing of soil which can

result in either excessive settlement or shear failure,

both of which can damage the structure.

RequirementsRequirements (Functional)(Functional)

Foundation Engineering

� Loads can be static or dynamic

� Static: Building, structure, dam, retaining wall,

embankment, etc.

� Dynamic: Earthquake, vibrating equipment, or

sensitive equipment

Subsurface Exploration

Purpose of subsoil exploration

Steps in Soil/Rock exploration

� Collection of Preliminary information: type of

structure, general use, topography, GWT

map, soil map

� Reconnaissance survey

� Site investigation: Planning, test boreholes,

collecting soil samples

Collection of Preliminary Information

Collection of Preliminary Information

)(6

)(3

7.0

7.0

buildingsconcretewideorsteelHeavySD

buildingsconcretenarroworsteelLightSD

b

b

=

=

Foundation Design

Geotechnical Engineer

• Where to sample

• How deep to sample

• What to sample

• How to sample

Soil borings

• Auger boring (Post hole and helical boring :

<5m),Power driven augers , 60-70m

• Wash boring

• Rotary drilling

• Percussion drilling

Wash boring

Scrapper bucket: sand mixed with pebbles

Clayey soils

Very soft soils

GEOLOGICAL MAP OF DELHI

A

R’

A’

E

D’

D

C’C

B’BG’

G

F’F

E’K

J’J

I’

I

H’

H

M’M

L’L

K’

R

Q

P’P

O’O

N’N

Q’

Soil Profiles of DelhiSoil Profiles of Delhi

Kakraula GaonSec-17

Dwaraka

Sec-12

Dwaraka Shahdra

Sec-7

Dwaraka

Filled up

soil

Sandy

silt

Silty

sand

Clayey

sand

Fine

sandQuarzite Gravely

sand

Depth

(m)

0

12

15

--13

--13

--22

--32

--9

--12

--11

--14

--10

--10

--42

--23

--30 --23

--14

--9

--9

--8

--21

--18

--27

--22

--23

--36

--30

--52

--50

--53

--23

--38

--14

--14

--16

--35

--38

--37

15 15

|--N

AA’

Dayal Singh College,

Lodi roadElectric Cremation,

Lodi roadRing Road Jn

Filled up

soil

Sandy

silt

Silty

sand

Clayey

sand

Fine

sandQuarzite Gravely

sand

|--N

Depth

(m)

--20

--17

--11

--8

--24

--23

--44

--29

--100

--9

--3

--2

--4

--25

--12

--6

0

15

--7

--12

--7

--6

--19

--19

--34

CC’

Sec-1,

NoidaSec-6,

Noida

Dallupura

Sewage Plant

Noida

Sec-61,

Noida

Sec-33,

NoidaSec-12,

Noida

Filled up

soil

Sandy

silt

Silty

sand

Clayey

sand

Fine

sandQuarzite Gravely

sand

|--N

Depth

(m)

--28

--20

--18

--19

--14

--32

--47

--12

--8

--6

--8

--7

--20

--16

--16

--11

--22

--20

--9

--9

--17

--21

--11

--15

--10

--8

--10

--20

--30

--20

--25

--7

--22

--21

--16

--64

--84

0

15

--10

--56

--15

--17

--18

--17 --53 --56

--22

--16

--5

--7

--8

--9

--6

--15

--39

--27

EE’

Filled up

soil

Sandy

silt

Silty

sand

Clayey

sand

Fine

sandQuarzite Gravely

sand

|--N

Tilak

BridgeMandi

House C.P

Pusa

Road Patel

Road Punjab

BaghRohini

RL 208

176

216

212

208209

180

196

192

188

184

200

--51

--42

--26

--29

--45

--50

--38

--40

--23

--34

--45

--48

--60

--51

--37

--12

--10

--21

--63

--70

--61

--12

--40

--15

--20

--30--25

--30

--26

--75

--18

--28

--38

--22

--25--29

--42

--14

--26

--25

--30

--35 --30

--29

--12

--15

--17

--20

--37

--40

GG’

Filled up

soil

Sandy

silt

Silty

sand

Clayey

sand

Fine

sandQuarzite Gravely

sand

|--N

Depth

(m)

ChanakyapuriB.D Marg

Lodi Road Golf LinksSarai Kale

Khan

Sec-1,

NoidaSec-62,

Noida

Sec-12,

Noida0

30

--39

--30

--14

--18

--21

--38

--34

--42

--39

--56--63

--25

--23

--35

--42

--19

--12

--26

--21

--25

--26

--29

--30

--18

--7

--10

--10

--15

--78

--22

--43

--46

--12

--26

--31

--26

--30

--42

--16

--18

--23

--31

--29

--13

--14

--28

--30

--19

--16

--8

--9

--25

--81

--13

--12

--14

--13

--20

--8

--10

--14

--15

--26

--34

--38

--77

--13

--17 --51

--55

--34

--34

--30

--39

--22

--32

--32

--25

--29

--32

--38

JJ’

RL 208

180

184

200

196

196

188

204

Filled up

soil

Sandy

silt

Silty

sand

Clayey

sand

Fine

sandQuarzite Gravely

sand

|--N

208207208209

212

--49

--27

--3

--10

--57

--43

--34

--18

--7

--15

--36

--22

--20

--47

--100

--35

--27

--7

--11

--46

--36

--51

--32

--17

--21

--60

--35

--40

--36

--15

--17

--20

Sewanagar

Shahjahah

Road

Boat ClubN.D.Rly.Stn

Chawri Bazar ISBT

RR’

GROUND WATER CONTOURS OF DELHI

DEPTH OF BED ROCK

SITE CHARACTERIZATION SITE CHARACTERIZATION

THROUGHTHROUGH

SEISMIC REFRACTIONSEISMIC REFRACTION

&&

MASW METHODSMASW METHODS

Seismic Refraction

Vertical GeophonesSource(Plate)

Rock: Vp2

ASTM D 5777

Soil: Vp1

oscilloscope

x1x2x3x4

t1t2t3t4

Note: Vp1 < Vp2

zR

Determine depthto rock layer, zR

Seismic Refraction

0.000

0.005

0.010

0.015

0.020 Travel Time (seconds)

0 10 20 30 40 50

Distance From Source (meters)

Horizontal Soil Layer over Rock

Vp1 = 1350 m/s

1

Vp2 = 4880 m/s

1z

x

2 V V

V Vc

c p2 p1

p2 p1=

−

+

Depth to Rock:zc = 5.65 m

xc = 15.0 m

x values

t values

Wooden Hammer

Connecting Cables

PEG 40Kg

McSeis-SX48

Geophones

28Hz,& 4.5HzBattery

Base plate

Accessories

Seismograph with all Accessories

McSeis-SX48

Geophones

28 Hz

4.5 Hz

Connecting

Cables

Field Arrangements

Seismic Refraction

Source: Propelled Energy Generator (PEG-40)

Hammer Mass: 36 Kg

Hammer drop height: 36-43 cm

Motor: 12 Volt (requires car battery)

Output Frequency band: 10-250 Hz

(depends on ground conditions)

Weight assembled with shields: 113 kg.

0

5

10

15

20

25

30

35

0 500 1000 1500 2000 2500 3000

Vp (m/s)Depth (m)

BMK

APS

SHL

D08

D22

0

5

10

15

20

25

30

35

0 200 400 600 800 1000

Vp (m/s)

Depth (m)

D10

D05

D13

D16

D19

D20

0

5

10

15

20

25

30

35

0 300 600 900 1200 1500 1800

Vp (m/s)

Depth (m)

DAP

JAP

TIJ

VIP

HAN

0

5

10

15

20

25

30

35

0 300 600 900 1200 1500 1800

Vp (m/s)

Depth (m)

KIN

INP

KHY

WPB

PUV

1D Velocity Profiles

-85

-90

-95

-100

Depth

(m)

0 10 20 30 40 50 60(m)

Distance

Velocity Model at JNU Campus, Opp. Girls Hostel

(km/sec)

Vp

0.300.540.791.03

1.28

Scale = 1 / 476

0.8

1.0

1.4

Velocity Profiles

- 7 0

- 8 0

- 9 0

- 1 0 0

Depth

( m )

0 1 0 20 3 0 4 0 5 0 6 0 7 0( m)

D i s t a n c e

J a n a k p u r i

( k m /s e c )

V p

0 . 3 0

0 . 4 50 . 6 00 . 7 50 . 9 0

S c a l e = 1 / 1 0 0 0

- 7 5

- 8 5

- 9 5

Depth

( m )

0 1 0 20 3 0 4 0 5 0 6 0 7 0( m)

D i s t a n c e

D D A P a r k , M a y a p u r i

( k m /s e c )

V p

0 . 3 4

0 . 6 3

0 . 9 3

S c a l e = 1 / 1 0 0 0

Velocity Profiles

VP at 40m depth

MASW

Source: wooden

hammer 11kg

Multichannel Records at JNU Site with Source Shifting along the Survey Line

0

10

20

30

40

50

60

-64 136 336

(a) at 69m (b) at 63m ( c) at 57m (d) at 51m (e) at 45m

(f) at 39m (g) at 33m (h) at 21m (i) at 9m (j) at 3m

0

5

10

15

20

25

30

0 200 400 600

Vs (m/s)Depth (m)

BSF

JNU

VK1

VK2

NDV

0

5

10

15

20

25

30

0 200 400 600

Vs (m/s)

Depth (m)

SHV

LSA

SAB

PVI

LAS

0

5

10

15

20

25

30

0 200 400 600

Vs (m/s)

Depth (m)

TUF

GKII

LTE

JAS

NFC

0

5

10

15

20

25

30

0 200 400 600

Vs (m/s)

Depth (m)

SIN

JNS

JAN

SAN

RKP

1D Velocity Profiles

2 0

1 5

1 0

5

0

Depth

( m )

7 1 7 2 7 3 7 4 7 5 7( m )

D i s t a n c e

J N U C a m p u s , O p p G i r l s H o s t e l

( k m / s )

V s

0 . 3 0

0 . 3 6

0 . 4 2

0 . 4 8

S c a l e = 1 / 6 6 6

Velocity Profiles

2 5 . 0

1 5 . 0

5 . 0

Depth

( m )

9 . 0 1 9 . 0 2 9 . 0 3 9 . 0 4 9 . 0 5 9 . 0( m )

D i s t a n c e

D e f e n c e l a n d , s e c - 2 2 D w a r k a

( k m / s )

V s

0 . 2 0

0 . 2 5

0 . 3 1

0 . 3 6

S c al e = 1 / 66 6

Velocity Profiles

25 .0

15 .0

5 .0

Depth

( m)

3 .0 13.0 23.0 33.0 43 .0 53 .0 63.0( m)

Distan ce

Open ground opp to Nanadadevi Apts, Sec-10 Dwarka

(km/ s)

Vs

0.21

0.26

0.31

Scale = 1 / 66 6

Average Shear Wave Velocity Vs30 Map of Delhi Region

Down-hole/cross-hole tests

� Down-hole/cross hole tests are in-situ test methods

- to measure dynamic soil/rock properties

- to determine P-wave and S-wave velocities

- to identify soil stratification

- to determine shear modulus, G =ρ.vs

Surface source S-wave arrival time, t

Depth, z

Transd. 1Layer 1

Layer 2Transd. 2

vs = dz/dt

Down-hole Seismic test

Down-hole test

Source of impulse Receiver

Receiver Source of impulse

a) Down-hole test b) Up-hole test

Cross-hole test

Source ReceiverL

2 boreholes arrangement

Cross-hole test

SourceReceivers

L

3 boreholes arrangement

Down-hole testing

Downhole

TestingOscilloscope

Cased Borehole

∆∆∆∆x

Test

Depth

Interval

HorizontalVelocity

Transducers(GeophoneReceivers)

packer

PumpHorizontal Plank

with normal load

Shear Wave Velocity:Vs = ∆∆∆∆R/∆∆∆∆t

z1z2

∆∆∆∆t

R12 = z12 + x2

R22 = z22 + x2

x

Hammer

By

Dr. Neelima Satyam D

Earthquake Engineering Research Centre

International Institute of Information Technology Hyderabad

Hyderabad-32

Email: neelima.satyam@iiit.ac.in; neelima.satyam@ gmail.com

GPR Demo Survey for utility

mapping at Habsiguda

Survey plan

GPR Data Collected

Plan of Utility Survey

10m x 5m

10mx 5m

Manhole 0.3m circularDia 200mm (Metallic)

Dia 600mm (Non-Metallic : RCC)

1st cable : bunch dia 40mm (network cables)

2nd cable single dia 60mm (High power cable)

3D Sectional view

Free Orbit View (sectional)

1st cable : bunch dia 40mm (network cables)

2nd cable single dia 60mm (High power cable)Dia 200mm (Metallic)

Dia 600mm (Non-Metallic : RCC)

0 m

1.0 m

0.7

0.9

0.75

0.19

0.19

0.940.93

0.88

0.82

3D View of Utility

Remarks

� 2 grids with 10m x 5m are made and surveyed

� Two sets of cables (red colored) one in bunch (40mm dia) mostly it is

network cables and other running as single cable (60mm dia) which is

a high power cable are shown along with depths mentioned (slide 8)

� One water pipe line (blue color) metallic with 200 mm dia was detected

with depths mentioned (slide 8)

� Sewer pipe non-metallic (grey color) line with 600 mm dia was

detected with depths mentioned (slide 8)

� Manhole invert levels are detected approximately at 2.2 m below GL

(since strata was highly saturated because of rain noise levels are

high)

� Rain water collection chamber was also identified.

Plan of Utility Survey

Grid Size 20m x 8m

A B

DC

Road to Uppal

Divider

bunch dia 60mm

Dia 100mm (Metallic)

Optical fiber / telephone

1* Bunch of cables

Others are single

1*

A-17º24'51"N 78 º32'50"E

B- 17º24'51"N 78 º32'51"E

C-17º24'51"N 78 º32'51"E

D-17º24'50"N 78 º32'51"E

3D Sectional view

)(3.0

3.0

)(

2

SANDB

B

B

B

S

S

CLAYB

B

S

S

p

f

f

p

f

p

f

p

f

p

+

+=

=

PROCEDURE

. � 30 cm diameter hole is trimmed where

the plunger is to be seated

Seating load of 4 kg is attached to the plunger

and dial gages reading is brought to zero

Results

Electrical resistivity method

L

RA=ρ

Four electrodes at equal spacing, 2 will be used to send electric

current and 2 Which are inside will measure the voltage drop

between them

Report

� Description of the scope of the investigation

� Description of the structure

� Site location (neighboring structures, drainage condition, veg type)

� Geological settings

� Details of field exploration (#, spacing, Db)

� Type of soil profile

� Lab tests

� Water table details

� Recommendations, limitations and conclusions of the investigation

Figures/graphs

� Site map

� Plan view of the exploration

� Bore log details

� Graphs corresponding to test data