Instrumented Sheet Pile Wall Load Test to Indirectly Measure Earth Pressure

Two parallel retaining walls were constructed from 10.4 m embedded PZ22 sheet piles in order to indirectly measure the amount of earth pressure induced during excavation. Selected sheets were instrumented in an effort to measure bending moment and deflection, whereby the induced earth pressure could be discerned. Four sheets were instrumented, each with 16 strain gages (eight gages per flange) to detect bending moment. Steel tubing was attached to four additional piles for use with an inclinometer to measure horizontal movement. The soil between the walls was excavated in five equal lifts over a ten day period until the total depth of excavation was 6.1 meters. Strain gages were continuously monitored while inclinometer readings were taken at the completion of each excavation lift. The qualitative and quantitative results of the load tests showed no mobilization of lateral earth pressure on the walls with an excavation depth of 6.1 meters.