Mini Pressure Meter

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APPLICATION OF PRESSUREMETER IN

GEOTECHNICAL ENGINEERING

PRACTICE

by

Dr.K.ILAMPARUTHIProfessor and Head,

Department of Civil Engineering,Anna University,

Chennai-600 025.



SEQUENCE OF PRESENTATION

IntroductionTypes of Pressuremeter

About Mini Pressuremeter

Pressuremeter Test ResultsInterpretation of Data

Correlation between PMT and SCPT

Conclusions



INTRODUCTION

The main objective of geotechnical investigation

is to find engineering properties of soil .Laboratory Testing on samples at best can only approximate field conditions.

In situ testing offers:Minimal soil disturbance

Testing under natural conditions

Cost effectiveness

Quicker testing

Pressuremeter is one such in situ testing device



PRESSUREMETER

• Development

• Literature



DATA

G=V0 ( Δ P/ Δ V)

E=2(1+μ)G

K 0=(P0 /σ’)



ABOUT MINI PRESSUREMETER

Developed by Louis Menard

It mainly consists of 3 parts:1. Probe - Sensor of the whole system which consists of a

hollow metal core, a thin inner membrane covering themiddle portion of the probe defined as the measuring celland a thick outer rubber pipe reinforced with metal strips,

guarding the measuring cell is known as guard cell.2. Monitoring device - Consists of a reservoir for themeasuring cell fixed to the brass block. On to this twopressure gauges of 16 bars capacity are used to monitorpressures in the measuring and guard cells.

3. The tubing - it is a coaxial nylon hose in which two nylontubes are provided one inside the other. one end isconnected to the coaxial inlet of the probe and the otherend is connected to the coaxial outlet of the coaxialconnector and in turn to the monitoring device.



ABOUT MINI PRESSUREMETER (Cntd…)

• Very useful in sand and soft clay whereundisturbed sampling is difficult or notpossible.

• Popular in European countries but yet topick up it’s momentum in India.

• Details of the usage of pressure meter is

well documented by Baguelin et al.(1978)and Clarke (1997)



EXPERIMENTAL SET UP FOR AIR CALIBRATION OF THE PROBE



APPLICATION OF THE PRESSURE INCREMENT

USING CO2 GAS



Pressuremeter tests and static cone penetration testswere conducted.

In sand and soft clay.

Net limit pressure values are compared with strengthparameters obtained from empirical correlations.

EXPERIMENTAL INVESTIGATION



FIELD TESTSI. Locations (Dominantly Sand)

• Kottivakkam• Vyasarpadi

• Parameswari Nagar

• Kotturpuram

• K.K.Nagar

• Thiruvanmiyur• Indira Nagar

II. Locations (Dominantly Clay)• Taramani

• Adyar

• Anna Nagar

• Nungambakkam

• Vyasarpadi

• Parameswari Nagar

• K.K. Nagar



PRESSUREMETER TEST RESULTS



TYPICAL PRESSUREMETER CURVE



AIR CALIBRATION CURVE FOR

NUNGAMBAKKAM



VOLUME CALIBRATION CURVE FOR

NUNGAMBAKKAM



PRESSUREMETER CURVE



CORRELATION BETWEEN SCPT & PMT



STATIC CONE PENETRATION RESISTANCE DIAGRAM

AT NUNGAMBAKKAM SITE



INTERPRETATION OF TEST DATA

Strength Parameters (Ф’ and Cu )

Deformation Modulas Em

Limit Pressure, P l

Bearing Capacity of Foundations

Settlement of Foundation

Location Depth (m) Pressuremeter Cone Resistance q



Location

(1)

Depth (m)

(2)

Pressuremeter Cone Resistance, qc

x 10 (kN/m2)(5)

Em X10 (kN/m2)(3)

P1 (kN/m2)(4)

Sand (loose and medium dense)

Kottivakkam 0.81.2

1.72.2

530825

8271440

6001100

13301550

380550

570700

Nungambakkam 4.5 94 100 140

Vyasarpadi 0.92.53.74.4

203138151297

330156167272

100302020

Parameswari Nagar 23

659492

10501330

320320

Kotturpuram Garden 23

3.7

290205245

525340585

400300360

K.K.Nagar 2.84

21093

180284

130100

Kotturpuram Park 0.7

1.72.73.7

300

4607201370

540

65510801600

245

380620650

Thiruvanmiyur 0.71.52.7

7609601340

81510001180

400640780

Indira Nagar 0.81.4

2.83.8

85146

187246

160380

460480

60100

150170



Clay (soft and medium stiff)

Taramani 0.7

1.5

2.5

4.2

220

106

148

236

405

155

155

260

120

20

20

30Adayar 0.5

1.5

2.5

560

550

380

460

460

320

120

90

55

Anna Nagar 0.7

1.7

848

520

1060

800

500

350

Nungambakkam 1.7

2.7

3.7

335

375

160

565

540

215

Vyasarpadi 1.7 24 42 60

Parameswari Nagar 0.9 940 1280 180

K.K.Nagar 1

2

70

310

172

420

90

100

KotturpuaramGarden

1 380 650 90



STRENGTH PARAMETERS

Pl* =10^ [(Ф-18)/12.8] (Ilamparuthi)

Pl

*

= b x 2^ [(Ф-24)/4]

Pl* =5.5 x Cu



SoilCondition

Author Baguelin

(1978)

Komornik(1969)

Crispel &Remy(1969)

Loose sand 2.5 to 3.7 3 to 4 3 to 5 -

Mediumdense sand

4 to 7.5 5 to 12 - -

Soft Clay 1.2 to 1.7 2.5 to 3.5 - -

Mediumstiff Clay

2.2 to 3.5 2.5 to 3.5 2 to 4 4.1 to 4.5

COMPARISON OF qc and Pl



COMPARISON OF Ф’ PREDICTED FROM SCPTAND PMT



RELATIONSHIP BETWEEN P i* AND Cu



UN-DRAINED COHESION VS LIMITPRESSURE



Cu COMPARISON BETWEEN SCPT ANDPMT



CONCLUSIONS

The correlation of P i

*/Cu =5.5 may be adopted for the

determination of undrained cohesion of clay of Chennai.

The Φ’ obtained from the results of pressuremeter and from the

static cone resistance by DeBeer (1943) theory compares well.

The correlation between cone resistance and limit pressure

recommended here compare well with recommendations of

Baguelin (1978) and Komornik (1969)

Operation of pressure meter is simple and quick so that it can

be extended to more potential sites.

Mini Pressure Meter

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