Rigid Pipe Proof Testing Under Excess Overfills with Varying Backfill Parameters: Section VIII - Analysis of Distress. Part 1 (with Appendices A through E)

摘要

Structural behavior of the reinforced concrete pipe culvert at Cross Canyon is evaluated on the basis of chronological observations of distress. Cracking patterns at successive overfills were recorded by mapping (sketching) and photographically, and diameter changes were assessed from extensometer readings. Records of significant crack widths were tabulated and are discussed in project diaries. These data are compiled in this section of the project report. The behavior of the various zones comprising the pipe is compared by ranking the zones on the basis of distress exhibited. Explanations of behavior are provided, based on observed soil stress profiles and neutral point analyses based thereupon. Zones with low modulus inclusions (induced trench, Method B backfill) exhibited superior performance at the higher overfills but not at the lower ones. A plot of permissible overfills for various pipe strengths, based on first appearance of 'industry-defined' failure or delamination, is furnished for the entrenched zones with ordinary (Method A) backfill.