Braced excavations: Temperature, elastic modulus, and strut loads

Relationships between strut loads, earth pressures, temperatures, and the m easurements provided by strain gauges are presented in this paper. A braced excavation up to 20-m deep, 9-20 m wide, and >650-m long constructed in co mpetent glacially derived sand, silt, and clay soils (including glacial til l) provided a significant amount of data for analysis. The excavation was s upported by soldier piles and lagging with pipe struts and was covered with decking during construction. A direct correlation between incremental chan ges in strut load and temperature was observed during the course of the pro ject. The few existing relationships between strut load and temperature wer e reexamined and were found to produce back-calculated elastic modulus valu es that were either without comparison or inconsistent with data from field tests and published sources. The relationships derived as a result of this work are supported by limited case-history data from other published sourc es and are consistent with practical application of elastic deformation con cepts and published soil modulus values.