This past week Teichert Construction completed pile driving installation for the abutment foundation at Brushy Creek. Forty-five to 60 ft long steel H-beams were driven into the soil beneath the abutment footing to provide a secure and stable foundation for the bridge widening. The piles are struck by a pile hammer with sufficient energy to drive the steel through the surrounding creek alluvium and deep into bedrock. Observation of the pile driving operations by County Inspection confirmed the existence of a hard sandstone layer (at shallow depths at the northern abutment) within the foundation's geological layer. This rock stratification provides a good substrate for the piles to secure the bridge footing and abutment. Other construction operations last week included the completion of exploratory drilling for the soil nail retaining walls at the northern and southern project limits. Verification nails were installed to confirm County Design's soil assumptions for the retaining walls. Soil nail retaining wall systems will be constructed as part of the Vasco Rd Safety Improvements project. "Soil nails" of various lengths are installed in bored holes along the hillside. The nails are then grouted in place with high strength concrete. As a complete system, the friction created between the grouted nails and existing soils secure the hillside and prevent slides from occurring. The current verification nail process consists of installing test nails at various locations to identify current soil conditions and quantifying the load the designed soil nails can sustain. Upon completion of this verification process, the "production" nails can be re-designed (shortened) to reduce costs if the existing soil conditions are better than originally anticipated.
Teichert Construction pile driving rig setting up at the southern abutment.
Pile driving at the southern abutment.
Piles driven (at the northern abutment) into the existing sandstone layer, which encountered competent bedrock at shallower depths than expected.
Teichert Construction drill rig beginning to bore for a verification soil nail.
