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Examination of Slope Stability Computation Procedures for Sudden Drawdown.

ADA187240

Publication Date	1987
Personal Author	Wright, S. G.; Duncan, J. M.
Page Count	178
Abstract	'Sudden' or 'rapid' drawdown is considered to occur when reservoir or other adjacent water levels are lowered at such a rate that little or no drainage occurs in an earth slope at the time the water level is being lowered. Slope stability analyses are routinely performed to calculate the factor of safety for earth slopes subjected to this condition. This study provides a basis for a number of important conclusions regarding the accuracy and the degree of conservatism of the procedures for analyzing rapid drawdown slope stability. The best procedure should have the following characteristics: a. The procedure should employ a measure of shear strength and pore pressure that reflects the actual properties of the soils in the slopes. b. The procedures should use a soundly bases technique for relating shear strength to effective consolidation pressures. and c. The procedure should not include strength components due to to negative pore water pressures to avoid overestimating factors of safety for conditions where partial drainage occurs during drawdown. A method with these characteristics can be conceived as a combination of methods currently in use.
Keywords	Soil mechanics Accuracy Slope Safety Shear strength Drainage Coefficients Pore pressure Water Soils Soil models Water table Strength(General) Stress analysis Stability Computations Drawdown Reservoir operations Soil stabilization Slope stability Sudden drawdown
Source Agency	Non Paid ADAS
NTIS Subject Category	50B - Civil Engineering 50D - Soil & Rock Mechanics
Corporate Authors	Army Engineer Waterways Experiment Station, Vicksburg, MS. Geotechnical Lab.
Document Type	Technical Report
Title Note	Final rept.,
NTIS Issue Number	198808
Contract Number	DACW39-86-M-0982 DACW39-86-M-1731

Examination of Slope Stability Computation Procedures for Sudden Drawdown.

Examination of Slope Stability Computation Procedures for Sudden Drawdown.
ADA187240

Publication Date	1987
Personal Author	Wright, S. G.; Duncan, J. M.
Page Count	178
Abstract	'Sudden' or 'rapid' drawdown is considered to occur when reservoir or other adjacent water levels are lowered at such a rate that little or no drainage occurs in an earth slope at the time the water level is being lowered. Slope stability analyses are routinely performed to calculate the factor of safety for earth slopes subjected to this condition. This study provides a basis for a number of important conclusions regarding the accuracy and the degree of conservatism of the procedures for analyzing rapid drawdown slope stability. The best procedure should have the following characteristics: a. The procedure should employ a measure of shear strength and pore pressure that reflects the actual properties of the soils in the slopes. b. The procedures should use a soundly bases technique for relating shear strength to effective consolidation pressures. and c. The procedure should not include strength components due to to negative pore water pressures to avoid overestimating factors of safety for conditions where partial drainage occurs during drawdown. A method with these characteristics can be conceived as a combination of methods currently in use.
Keywords	Soil mechanics Accuracy Slope Safety Shear strength Drainage Coefficients Pore pressure Water Soils Soil models Water table Strength(General) Stress analysis Stability Computations Drawdown Reservoir operations Soil stabilization Slope stability Sudden drawdown
Source Agency	Non Paid ADAS
NTIS Subject Category	50B - Civil Engineering 50D - Soil & Rock Mechanics
Corporate Authors	Army Engineer Waterways Experiment Station, Vicksburg, MS. Geotechnical Lab.
Document Type	Technical Report
Title Note	Final rept.,
NTIS Issue Number	198808
Contract Number	DACW39-86-M-0982 DACW39-86-M-1731