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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.
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SEQUENCE OF PRESENTATION
IntroductionTypes of Pressuremeter
About Mini Pressuremeter
Pressuremeter Test ResultsInterpretation of Data
Correlation between PMT and SCPT
Conclusions
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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
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PRESSUREMETER
• Development
• Literature
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DATA
G=V0 ( Δ P/ Δ V)
E=2(1+μ)G
K 0=(P0 /σ’)
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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.
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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)
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EXPERIMENTAL SET UP FOR AIR CALIBRATION OF THE PROBE
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APPLICATION OF THE PRESSURE INCREMENT
USING CO2 GAS
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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
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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
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PRESSUREMETER TEST RESULTS
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TYPICAL PRESSUREMETER CURVE
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AIR CALIBRATION CURVE FOR
NUNGAMBAKKAM
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VOLUME CALIBRATION CURVE FOR
NUNGAMBAKKAM
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PRESSUREMETER CURVE
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PRESSUREMETER CURVE
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PRESSUREMETER CURVE
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PRESSUREMETER CURVE
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PRESSUREMETER CURVE
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CORRELATION BETWEEN SCPT & PMT
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STATIC CONE PENETRATION RESISTANCE DIAGRAM
AT NUNGAMBAKKAM SITE
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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
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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
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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
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STRENGTH PARAMETERS
Pl* =10^ [(Ф-18)/12.8] (Ilamparuthi)
Pl
*
= b x 2^ [(Ф-24)/4]
Pl* =5.5 x Cu
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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
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COMPARISON OF Ф’ PREDICTED FROM SCPTAND PMT
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RELATIONSHIP BETWEEN P i* AND Cu
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UN-DRAINED COHESION VS LIMITPRESSURE
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Cu COMPARISON BETWEEN SCPT ANDPMT
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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.