calibration of design methods for slope stabilization and earth retention
DESCRIPTION
Calibration of Design Methods for Slope Stabilization and Earth Retention. J. Erik Loehr Civil and Environmental Engineering University of Missouri - Columbia. General Design Approach. Motivation. Design methods appear conservative Have performance data, but it’s underutilized - PowerPoint PPT PresentationTRANSCRIPT
Calibration of Design Methods for Slope Stabilization and Earth Retention
J. Erik Loehr
Civil and Environmental EngineeringUniversity of Missouri - Columbia
General Design Approach
RaxialR
Reinforcing Member
Potential Sliding Surface
transverseR
Motivation Design methods appear conservative Have performance data, but it’s
underutilized Would like to make prudent use of
performance data to improve design methods
“Calibration” of Design Method Objective is design method that
predicts F=1.0 when deformations becomes “just unacceptable”
F
1.00.0
Initial Performance Function
Calibrated Function
limit
Required Data Deformations as function of time
Inclinometers Surface surveys
Piezometric levels as function of time
Soil/Rock properties
Loads/moments in members not required, but helpful
I435-Wornall Road Site
June 2001
I435-Wornall Road “As-Built”
Stiff to very stiff clay
Hard Formation
Soft to medium clay3 rows driven perpendicular (8-ft)
11 rows driven vertical (8-ft)
1 row driven vertical (5-ft)
2 rows driven vertical (3.5-ft)
N
I435-Wornall Site Instrumentation
I-1I-2
I-3I-4IM-1
IM-2
IM-3
IM-4P-1,2
P-3,4
Legend:Piezometers
Instrumented Members
Inclinometers
N
Approx. Slide Extent
Crest
Toe
I435-Wornall Site: Piezometric Levels0
2
4
6
8
10
N D J F M A M J J A S O N D J F M A M J J A
Date
Dept
h of
Wat
er F
rom
Gro
und
Surfa
ce (f
t)
P-1P-2P-3P-4
2001 2002 2003
P1P2
P4P3
I435 Site Piezometric LevelsUpper Stratum
Middle Stratum
Lower Stratum April 11, 2002
Upper Stratum
Middle Stratum
Lower Stratum May 13, 2002
Upper Stratum
Middle Stratum
Lower Stratum
July 12, 2002
Theoretical Factors of Safety
4/11/02
5/13/02
6/10/02
7/12/02
8/22/02
1.0
1.1
1.2
1.3
1.4
1.5
M A M J J A S O N D JDate
Fact
or o
f Saf
ety
Uncalibrated Method
Unreinforced
F calculated using measuredpore pressure conditions
I435-Wornall Road Performance
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
N D J F M A M J J A S O N D J F M A M J J ADate
Cum
ulat
ive D
ispla
cem
ent (
in)
I-1
I-2
I-3
I-4
2001 2002 2003
Stage 1 Stage 2 Stage 3
Field Performance Function
1.0
1.1
1.2
1.3
1.4
1.5
0.0 0.5 1.0 1.5 2.0 2.5 3.0Cumulative Lateral Displacement (in)
Fact
or o
f Saf
ety
Measured Performance
Extrapolated Performance
Inferred Performance
Field Performance Functions
1.0
1.1
1.2
1.3
1.4
1.5
0.0 0.5 1.0 1.5 2.0 2.5 3.0Cumulative Lateral Displacement (in)
Fact
or o
f Saf
ety
Measured Performance
Extrapolated PerformanceCalibrated Performance
Inferred Performance
Theoretical Factors of Safety
5/13
/02
4/11
/02
6/10
/02
7/12
/02
8/22
/02
1.0
1.1
1.2
1.3
1.4
1.5
M A M J J A S O N D JDate
Fact
or o
f Saf
ety
Calibrated MethodUncalibrated MethodUnreinforced
F calculated using measuredpore pressure conditions
Conclusions Approach at least produces method
that is consistent with observed field behavior
Non-uniqueness in approach can be addressed by performing additional calibrations
Limited to application for similar techniques
Prudent basis for incrementally improving design over time
Large-scale modeling
Acknowledgements Project Sponsors
Missouri Department of Transportation, project RI98-007
National Science Foundation, project CMS0093164
Recycled Materials Resource Center, UNH Epoch Composite Products, Lamar, MO The Judy Company, Kansas City, MO
John Bowders and Hani Salim, MU Faculty
Tom Fennessey, MoDOT MU Graduate students
Calibration based on I435-Wornall Site
0
1
2
3
4
5
6
7
8
9
10
0 200 400 600 800 1000 1200 1400 1600Limit Soil Pressure (psf)
Dept
h (ft
)
f ' = 27°c ' = 56.5 psfg = 125 pcfu =0
Shaded region indicates range suggested by calibrations for I-435 Wornall Road site