Helical Pile Underpinning for Temporary Remediation of Steel Lattice Tower Concrete Foundations Founded on Bay Mud-PPT Presentation

PPT Presentation

Pdf Summary

The presentation describes using helical piles to temporarily remediate steel lattice tower foundations affected by erosion and settlement in bay mud. A helical pile is a steel shaft with one or more helical bearing plates, installed by screwing it into the ground. It can support structures through weak soils.<br /><br />Bay mud is fine-grained, unconsolidated, low-strength soil found near shorelines. It is prone to settlement and may liquefy during earthquakes. These conditions can undermine tower foundations, while erosion and concrete deterioration further reduce support.<br /><br />Two tower retrofit examples are presented. For a four-legged lattice tower, challenges included eroded bearing soils, bay mud deposits, deteriorated concrete, limited installation access, and installing piles through water. The design used eight helical piles per leg, for 32 total: sixteen 3-inch-diameter and sixteen 5.5-inch-diameter piles. Custom steel beam brackets were secured with epoxy anchors and welded to the piles.<br /><br />A separate dead-end tower near a river had eroded bearing soils, exposed timber piles, and reduced tension capacity. Its design used four helical piles per leg, HP14x89 beams, steel plates, epoxy anchors, and tie-back caps.<br /><br />The presentation emphasizes that pile and bracket configurations are tailored to site conditions and foundation needs. The opinions and recommendations are those of the presenters; the presentation does not guarantee their accuracy or reliability, nor does DFI endorse them.

Keywords

helical piles

steel lattice tower

foundation remediation

bay mud

erosion

settlement

earthquake liquefaction

retrofit design

epoxy anchors

dead-end tower