Pressuremeters and
other In Situ Testing
Equipment
Presented by : Louis Marcil, Eng.
Roctest Webinar April 2012
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Presentation Overview
INTRODUCTION
1. Pressuremeters (PMT)
1.1 Description of the Test
1.2 Description of the Equipment (Types of Pressuremeters)
1.3 Main Applications
1.4 Advantages and Limitations
2. Other In Situ Test Equipment
2.1 Vane Testers
2.1 Cone Penetration Test Equipment (CPT)
CONCLUSION
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INTRODUCTION
IN SITU TESTING
Pyramid Initial Slope
Proper characterization of mechanical
properties of the ground onto which
structures are to be built has a great
importance.
Rhomboidal ‘bent’ Pyramid, Egypt
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INTRODUCTION
IN SITU TESTING
Means for characterizing the ground:
1) Laboratory Testing
2) In Situ Testing
- Penetration Resistance Measurement (SPT, CPT)
- In Situ Permeability Tests (Packer Test, Rising Head Test...)
- Strength and compressibility testing (PMT, Vane Testing, Plate load
tests, Flat Dilatometer…)
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1 Pressuremeters
PMT = An in situ loading test executed
by radial expansion of a cylindrical
cavity. The stresses are exerted on the
walls of a borehole by mean of a
pressurized fluid acting on one
inflatable membrane.
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1.1 Test Description
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1.1 Test Description
TYPICAL PRESSUREMETER CURVE
• Progressive loading in
steps. Waiting period
required at every step for
stabilization before
recording pressure and
radial expansion
• Unload-loading cycle
• Test duration : 10 min
• Standards: ASTM 4719-07
NF P94-110-1, EN_ISO_22476-4
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1.1 Test Description
General Testing Procedure
•Tests executed at various
depths in the same borehole
•Common spacings : 1 to 3 m.
•Borehole cannot be done in
one pass
•Results are presented for
each elevation giving general
profile of the soil.
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1.1 Test Description
Main Parameters:
Pressuremeter modulus (E)
Limit pressure (Pl)
  pb 

E = 2 (1 + R ) x Vm x 
 v 
Where:
- R : Poisson's ratio of the soil/rock
: the volume of the cavity at mid-point of
.-theVmtesting
zone
 pb
 v : the variation of volume of the cavity
due to the variation of the applied pressure
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1.1 Test Description
The Making of the Borehole = Critical to make successful tests ! ! !
Borehole = Adequate if:
1. Undisturbed Soil
2. Borehole of Proper Diameter
3. Smooth wall borehole
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1.1 Test Description
Various drilling methods suggested in Standards as per type of soils.
Use of rotary drilling with axial injection (towards hole bottom) of mud is applicable in most
cases. Slotted casing in large-gravels soils.
•
Ideally: Roller bit for silt, sand, and gravel. 2 7/8 in. to 3 inches. Three-wing bit for clayey soils.
•
Diameter of rods must be one or two sizes smaller than diameter of bit to allow good flow up of cuttings
•
Do not ram the bit up and down as this will result in an oversized hole
•
Popular method : 3-in hollow auger for first portion of the borehole + use of rotary bit in the testing zone only

Go slowly:
Injection pressure:
< 500 kPa with borehole full of mud
Bit rotation:
< 60 rpm
Flow :
< 15 liters per minute
Bit pressure:
< 200 kPa (100 kg in a 76 mm borehole)
Typical advance rate: 15 to 25 cm/minute
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1.2 The Equipment
VARIOUS TYPES OF PRESSUREMETERS:
- Pre-Boring vs Self-Boring Pressuremeters
- Volume Variations vs Direct Radial Strain Measurements
- Mono-cellular vs Tri-cellular Probes
- Diameter of the Probe : 33 mm to 95 mm
- Type of Loading: Pneumatic vs Hydraulic
- Reading Mode: Manually vs Automatically
- Working Capacity: 4,000 kPa to 30,000 kPa
- Various Sensitivities
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1.2 The Equipment
Soil Pressuremeters:
Menard Pressuremeter
(Volumetric, pneumatic, tri-cellular probe)
Texam Pressuremeter
Trimods Pressuremeter
(Volumetric, hydraulic, mono-cellular probe
(Radial expansion measurement,
hydraulic, mono-cellular probe)
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1.2 The Equipment
Rock Pressuremeters:

Model PROBEX

Capacity pressure:

Hydraulically loaded

Fiberglass-reinforced polyurethane membrane
Capacity modulus:
0.01 to 30 GPa approx.
Testing depth to (date): 300 meters


30 000 kPa (3500 psi)
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1.2 The Equipment
Rock Pressuremeter /
Borehole Dilatometer:

Model DMP
Measures radial deformations by
mean of 3 LVDT disposed at 120 °


Capacity pressure: 20 000 kPa

For used in soft to moderately hard
rock (Maximum modulus of 50 GPa)
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1.2 The Equipment
Self-Boring Pressuremeters:
•
Interesting tool because minimizes remolding
•
Confined to soils with few gravels
BOREMAC Pressuremeter
(volumetric, hydraulic, mono-cellular probe)
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1.3 Main Applications
1)
Shallow foundations
2)
Laterally loaded piles
3)
Vertically loaded piles
4)
Compaction control
5)
Design of pavement
Of less use for slope stability problems and embankments
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1.3 Main Applications
Semi-empirical methods vs. methods based on the theory of elasticity
Semi-empirical method:
1) Bearing Capacity = K x Pl
The factor of proportionality K is function to:
- Relative depth
- Shape of the foundation
- Type of ground
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1.3 Main Applications
2) Settlement :
S
1.2
p p qa B
qa 2 B / 0,6  
3
9 EM
9 EM
Ref: Canadian Foundation Engineering Manual
- S is the settlement
- EM is the pressuremeter modulus.
- qa is the allowable bearing capacity
- λ2 and λ3 are the coefficients of shape of footing, (L/B)
- B is the width of the footing
- αp is a coefficient of structure (function to type of soils and E/Pl)
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1.3 Main Applications
3) Lateral Deflection
of laterally-loaded
structures
P-Y Curve:
Various Methods
Robertson et al.
Example :
VGS Reduction of Rock Pressuremeter Tests
Design P-Y Curves
54-inch Diameter Rock Socket
(Courtesy: Failmezger, In Situ Soil Testing, VA)
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1.3 Main Applications
Design of High Rise
Buildings
Petronas Towers
AT&T Tower
(Kuala Lumpur, Malaysia)
(Chicago, USA)
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1.4 Advantages and Limitations
LIMITATIONS
• Well-trained operator is required for ensuring:
Making a good borehole
Taking care not to burst too many membranes
• Soils with large gravels are difficult to test. A slotted casing
might be required.
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1.4 Advantages and Limitations
ADVANTAGES
• Versatile: Can be performed in most types of
soils and soft rocks
• Gives an in situ stress strain curve
• The loading sequence can be adapted
according to the application (long or rapid
loading, cyclic loading)
• Close analogy with laterally-loaded piles
• Validity of the test can be controlled from the
shape of the curve.
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2. Other In Situ Testing Equipment
Various types of in situ tests can be performed:
Penetration Test (SPT, CPT), Vane Test, Plate Loading Test, Flat Dilatometer Test, Packer Test,
Compaction Control Test, etc.
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2.1 Vane Shear Tester
• For cohesive soils only
• Test Description
• Quick and Easy
• Used either for designing of shallow or deep
foundations
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2.1 Vane Shear Tester
Su
= K (as - af) x C
Where:
Su
C
K
as
af
=
=
=
=
=
the undrained shear strength in kg/cm2
vane form constant in 10-2 x cm-3
calibration constant for the torque recording head in kg m / cm
distance in cm between the zero torque reference line to the peak of the curve
distance in cm between the zero torque reference line and the circular arc scribed
during the first 15 degrees of rotation (corresponds to rod friction)
Recording sheets from the Model M-1000 Vane Tester
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2.2 Cone Penetration Test
Dynamic Cone Penetration Test:
Procedure: Record number of blow
counts required for trusting a conical
point into the ground. Size and shape
of the point, weight, and the mass
falling distance are standardized.
Used for soil classification and for
compaction control.
Model PEM-1 Cone
Dynamic Penetrometer
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2.2 Cone Penetration Test
Static Cone Penetration Test (CPT) :
The most common penetration test.
Pushed into the ground.
Recording of: tip resistance, friction
resistance, pore pressure and others.
Models:
1
2
-Handsounding Cone Penetrometer (1)
-Mechanical Cone (2)
-Mechanical Friction Cone (3)
-Electric Cones (4)
4
3
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2.2 Cone Penetration Test
Static Cone Penetration Test (CPT) :
Interpretation and use of results:
Soil Classifications using cone and friction resistance.
Determination of various parameters from empirical correlations:
For instance:
- Stiffness and relative density in cohesionless soils.
- Undrained Shear Strength in cohesive soils.
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CONCLUSION
Roctest has specialized in pressuremeters
PMT not a routine testing method
Required well-trained operator
Special attention must be given for the making of the borehole
PMTproves to be a useful tool for applications :
1) Such as for the laterally loaded foundations, and high rise
buildings
2)
Where undisturbed samples cannot be obtained, and where
other conventional tests cannot be done (rock & weakly cemented
material)
3) On large projects where it is justified to put efforts to get better
information on the soil/rock
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Thank you !
Questions ?
(Courtesy of
ODOT)
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