FIRST-ORDER UNCERTAINTY ANALYSIS OF SOIL DEFORMATION AND STABILITY

THIS PAPER REPORTS ON PROBABILISTIC METHODS OF ANALYSING THE DEFORMATION AND STABILITY OF SOIL FOUNDATIONS OR EMBANKMENTS. THE SPECIFIC PROCEDURES DESCRIBED WERE DEVELOPED ORIGINALLY FOR AN EARTH DAM IN RESPONSE TO QUESTIONS AS TO WHETHER ADDITIONAL SOILS EXPLORATION SHOULD BE UNDERTAKEN IN THE LIGHT OF THE OBSERVED DISPERSION IN THE DATA ALREADY AVAILABLE. METHODS OF ESTIMATING THE TOTAL UNCERTAINTY FACED BY THE ENGINEER PREDICTING THE DEFORMATIONS AND STABILITY OF SOIL STURCTURES OR FOUNDATIONS ARE DISCUSSED. THIS TOTAL UNCERTAINTY INCLUDES UNCERTAINTY IN THE SOILS PROPERTIES (CAUSED BY LIMITED SPATIAL SAMPLING AND BY TESTING VARIABILITY), SUBSEQUENT UNCERTAINTY IN THE PREDICTED QUANTITIES (E.G., DEFORMATIONS), AND UNCERTAINTY IN THE ENGINEERING THEORY OR ALGORITHM USED TO PREDICT THESE QUANTITIES. THIS PAPER DISCUSSES A PRACTICAL FORMULATION OF SUCH PROBLEMS WHICH PRODUCES A FIRST - ORDER UNCERTAINTY ANALYSIS. SECONDLY, IT PRESENTS A NUMERICAL EXAMPLE WHICH INVOLVES EMBANKMENT STABILITY ANALYSIS AND WHICH MAKES USE OF REGRESSION ANALYSIS TO ESTABLISH SPATIAL SOILS PROPERTY VARIATIONS AND THE UNCERTAINTY IN THEIR ESTIMATES. /TRRL/