St. Jacques-Pullman MSE Walls – Lessons Learned

The St. Jacques-Pullman MSE walls were part of an early works package ahead of the larger Turcot Interchange redevelopment in Montreal. The walls comprise a six-tiered MSE wall configuration 30 m high constructed into an existing escarpment with global and compound stability challenges. The project included complex construction staging with tie-ins to an existing bridge and two new bridges. The solution developed comprised a composite soil nail slope / MSE wall system. This was the first MTQ project using soil nails to resolve global stability which helped reduce excavation volumes and costs for the project.

Limit equilibrium and finite element analysis was completed to support the design. Detailed deformation monitoring was completed during construction and agreed well with the finite element model estimates.

This technically challenging project provides a detailed example of complex wall geometries, in particular tiered MSE wall designs and the complexities in analyzing compound stability.  The paper will provide a successful example of aligning the geotechnical engineer’s responsibilities with the MSE wall supplier’s responsibilities to assure the roles for each party on the project are properly addressed this complex geotechnical design case.