Rigid Pipe Proof Testing under Excess Overfills with Varying Backfill Parameters. Section VI - Analysis of Embankment Settlements

摘要

Settlement data obtained from fluid settlement platforms, plate and rod settlement platforms and leveling at five zones of the Cross Canyon, 84-in. (2.13-m), reinforced concrete pipe, under 183 ft (55.8-m) of overfill, are employed in calculations of quasi-theoretical crown loads, using methods developed by Marston and Spangler. Soil stresses measured by stressmeters at the soil-pipe interface are compared with quasi-theoretical stresses assessed with settlement ratios obtained: (1) from the aforementioned data; and (2) using values published by Spangler based on statistical analyses of many past installations. Zones 1 (horizontal, steel, tension struts), 4 (entrenched), and 8 (entrenched, with polystyrene plank overlayment) are treated as positive projecting; Zones 9 (uncompacted soil overlayment) and 10 (baled straw overlayment) are treated as negative projecting with induced trench construction. Pipe in the five zones was Class II, with a 1,000D load rating. The analysis failed completely to predict the non-linearity of the soil stress-overfill functions where recommended, handbook values of the settlement ratio were used, and predicted soil stresses were much higher than the measured ones.