Cyclic Triaxial Nov 2007
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Soil Mechanics Presentaion
The Wykeham Farrance Cyclic Triaxial System
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
The wykeham Farrance Cyclic Triaxial System was the first pneumatic system commercially produced The cyclic triaxial system is used to investigate problems associated with liquefaction, blasting shear modulus and strength degradation. One of the benefits of the Wykeham Farrance cyclic triaxial system it can replicate any wave shape associated with these problems. Frequency and wave shape can very from one investigation to another.
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Cell bas showing exit port for the base bender element
Access ring for transducer cables
TRI-CELL plus
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
All the control and data acquisition functions are performed by the (IMACS) Integrated Management and Control System. The IMACS has 3 control channels and 13 data acquisition channels. Axis one is the axial stress Axis two cell pressure Axis three back pressure
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
The cyclic loading is delivered via a through rod double acting pneumatic actuator which is fixed to the crosshead of the standard Wykeham Farrance triaxial load frame. The actuator has a +/- 5kN capacity but for monotonic shearing higher than 5kN we have a piston clamp that can be screwed up against the load frame crosshead which will lock the actuator in any position. Higher loads can be achieved using the load frame.
Piston Clamp
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
The feed back for load and waveshape control is from an internal submersible 5kN load cell. The feed back must be from a submersible load cell to avoid problems caused by ram friction and changes in confining pressure. These are eliminated in the PID control
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Suction top cap for connecting the load cell To the sample This part connects to the load cell base with a vacuum line passing through the triaxial cell top
Top cap with vacuum ring attached
Having a rigid connection between the sample and the loading mechanism is essential for all stages of the test. It allows the application of a seating load or zero load on the sample which will remain throughout the test.
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
A critical part of cyclic loading and waveshape control is the alignment of the actuator and the triaxial cell ram. The Wykeham Farrance system has two adjustments. One adjusts in the horizontal plane and the other a ball seat aligns in the vertical.
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
The system has two displacement Transducers. One is mounted in series with the pneumatic actuator. This is to indicate the ram position in the actuator. The second is mounted on the triaxial cell ram to measure sample displacement . Two are required because we zero the sample displacement transducer during the test
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Cell and back pressure are controlled by digitally controlled valves with the transducers mounted adjacent to the valve. The valves are mounted on an auxiliary air receiver with air filter to ensure clean air is supplied to the valves
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Pore water pressure is measured at the base of the triaxial cell using a pressure transducer and de-airing block. We have a valve either side of the pore water pressure block. The inner valve to allow water to be flushed through the de-airing block and to allow in situ calibration check of the pressure transducer.
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
The application of back pressure to the sample is controlled through a solenoid valve, open and close signal are sent via the IMACS. This is done automatically in saturation consolidation and for drained or undrained shear
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Volume change is measured through a volume change transducer. This is positioned in the back pressure line giving a direct measurement of volume change. The volume change transducer is equipped with a change over valve which reverses the flow to increase the volume change range from 100cc upwards.
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Test set up page for consolidation, stress path, shear and cyclic stages Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Continuous Saturation
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Consolidation Page Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Stress Path page
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Shear Page Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Cyclic Graph
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Charting Options
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Playback file allows imported waveshapes to applied to the sample by selecting non standard test in the cyclic shear set up parameters
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Playback Converter
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
70000
60000
50000
40000
30000
20000
10000
0 0
20
40
60
80
100
120
140
160
180
200
220
240
260
280
300
320
340
360
380
Waveshape data displayed in Excel
Cyclic Triaxial System Nov 2007
400
420
440
460
480
500
520
Soil Mechanics Presentaion
Cyclic Cell Pressure Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
30 20 10 0 -10 -20 -30 -40 15 10
(% )
Test data showing the build up of excess pore water pressure and strain during cyclic loading
Deviator stress, q (kPa)
40
0 -5 -10 -15 1 0.8 0.6 u/p' c
Excess pore pressure ratio,
Axial strain,
a
5
0.4 0.2 0 -0.2 0
5
10
15 20 Number of cycles, N
Cyclic Triaxial System Nov 2007
25
30
Soil Mechanics Presentaion
σ ’v=0
−τd
σ ’h=0
σ ’v0
σ ’v +τd
σ ’h0
σ ’h 50
p' c = 100 kPa f = 0.1 Hz q cyc = 30 kPa
PTL
40
Deviator stress, q (kPa)
30 20 10 0 Test start
-10 -20 -30 -40 -50 0
20
40
60
80
100
Mean normal effective stress, p' (kPa)
Cyclic Triaxial System Nov 2007
120
Soil Mechanics Presentaion
The cyclic triaxial system is used to investigate problems associated with liquefaction, blasting shear modulus and strength degradation. One of the benefits of the Wykeham Farrance cyclic triaxial system it can replicate any wave shape associated with these problems. Frequency and wave shape can very from one investigation to another.
• • • •
Liquefaction Blasting Shear Modulus & Damping Ratio Strength Degradation
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Earthquake Rail track Blasting
Waveshapes are different, they can be reproduced saved or imported from an outside source. Waveshapes can be manually inputted with a 40000 point description
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Cyclic Triaxial System Nov 2007
The Wykeham Farrance Cyclic Triaxial System
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
The wykeham Farrance Cyclic Triaxial System was the first pneumatic system commercially produced The cyclic triaxial system is used to investigate problems associated with liquefaction, blasting shear modulus and strength degradation. One of the benefits of the Wykeham Farrance cyclic triaxial system it can replicate any wave shape associated with these problems. Frequency and wave shape can very from one investigation to another.
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Cell bas showing exit port for the base bender element
Access ring for transducer cables
TRI-CELL plus
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
All the control and data acquisition functions are performed by the (IMACS) Integrated Management and Control System. The IMACS has 3 control channels and 13 data acquisition channels. Axis one is the axial stress Axis two cell pressure Axis three back pressure
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
The cyclic loading is delivered via a through rod double acting pneumatic actuator which is fixed to the crosshead of the standard Wykeham Farrance triaxial load frame. The actuator has a +/- 5kN capacity but for monotonic shearing higher than 5kN we have a piston clamp that can be screwed up against the load frame crosshead which will lock the actuator in any position. Higher loads can be achieved using the load frame.
Piston Clamp
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
The feed back for load and waveshape control is from an internal submersible 5kN load cell. The feed back must be from a submersible load cell to avoid problems caused by ram friction and changes in confining pressure. These are eliminated in the PID control
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Suction top cap for connecting the load cell To the sample This part connects to the load cell base with a vacuum line passing through the triaxial cell top
Top cap with vacuum ring attached
Having a rigid connection between the sample and the loading mechanism is essential for all stages of the test. It allows the application of a seating load or zero load on the sample which will remain throughout the test.
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
A critical part of cyclic loading and waveshape control is the alignment of the actuator and the triaxial cell ram. The Wykeham Farrance system has two adjustments. One adjusts in the horizontal plane and the other a ball seat aligns in the vertical.
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
The system has two displacement Transducers. One is mounted in series with the pneumatic actuator. This is to indicate the ram position in the actuator. The second is mounted on the triaxial cell ram to measure sample displacement . Two are required because we zero the sample displacement transducer during the test
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Cell and back pressure are controlled by digitally controlled valves with the transducers mounted adjacent to the valve. The valves are mounted on an auxiliary air receiver with air filter to ensure clean air is supplied to the valves
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Pore water pressure is measured at the base of the triaxial cell using a pressure transducer and de-airing block. We have a valve either side of the pore water pressure block. The inner valve to allow water to be flushed through the de-airing block and to allow in situ calibration check of the pressure transducer.
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
The application of back pressure to the sample is controlled through a solenoid valve, open and close signal are sent via the IMACS. This is done automatically in saturation consolidation and for drained or undrained shear
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Volume change is measured through a volume change transducer. This is positioned in the back pressure line giving a direct measurement of volume change. The volume change transducer is equipped with a change over valve which reverses the flow to increase the volume change range from 100cc upwards.
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Test set up page for consolidation, stress path, shear and cyclic stages Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Continuous Saturation
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Consolidation Page Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Stress Path page
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Shear Page Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Cyclic Graph
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Charting Options
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Playback file allows imported waveshapes to applied to the sample by selecting non standard test in the cyclic shear set up parameters
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Playback Converter
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
70000
60000
50000
40000
30000
20000
10000
0 0
20
40
60
80
100
120
140
160
180
200
220
240
260
280
300
320
340
360
380
Waveshape data displayed in Excel
Cyclic Triaxial System Nov 2007
400
420
440
460
480
500
520
Soil Mechanics Presentaion
Cyclic Cell Pressure Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
30 20 10 0 -10 -20 -30 -40 15 10
(% )
Test data showing the build up of excess pore water pressure and strain during cyclic loading
Deviator stress, q (kPa)
40
0 -5 -10 -15 1 0.8 0.6 u/p' c
Excess pore pressure ratio,
Axial strain,
a
5
0.4 0.2 0 -0.2 0
5
10
15 20 Number of cycles, N
Cyclic Triaxial System Nov 2007
25
30
Soil Mechanics Presentaion
σ ’v=0
−τd
σ ’h=0
σ ’v0
σ ’v +τd
σ ’h0
σ ’h 50
p' c = 100 kPa f = 0.1 Hz q cyc = 30 kPa
PTL
40
Deviator stress, q (kPa)
30 20 10 0 Test start
-10 -20 -30 -40 -50 0
20
40
60
80
100
Mean normal effective stress, p' (kPa)
Cyclic Triaxial System Nov 2007
120
Soil Mechanics Presentaion
The cyclic triaxial system is used to investigate problems associated with liquefaction, blasting shear modulus and strength degradation. One of the benefits of the Wykeham Farrance cyclic triaxial system it can replicate any wave shape associated with these problems. Frequency and wave shape can very from one investigation to another.
• • • •
Liquefaction Blasting Shear Modulus & Damping Ratio Strength Degradation
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Earthquake Rail track Blasting
Waveshapes are different, they can be reproduced saved or imported from an outside source. Waveshapes can be manually inputted with a 40000 point description
Cyclic Triaxial System Nov 2007
Soil Mechanics Presentaion
Cyclic Triaxial System Nov 2007
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