Computer Aided Design of Soldier Pile and Lagging Retaining Walls with Tieback Anchors

Soldier pile and lagging walls are used to support open excavations and restrict lateral movements. They also provide an increased factor of safety to nearby structures and utilities against excessive deformations and loss of bearing capacity. The soldier pile and lagging wall consists of structure H- beams driven into the ground with wood lagging installed between the flanges of the beams to retain the soil. With the use of tieback anchors as bracing, they can provide an unobstructed area for constructed area for construction. The design of the soldier pile and lagging wall consists of developing a pressure for the soil conditions and determining the number and location of the anchors for a given H-beams section modulus. The pressure enveloped for braced excavations differ from Rankines active state. A braced excavation deforms more laterally at the bottom of the excavation than the top due to the installation of the anchors. A C language computer program was developed to optimize the design of the soldier pile and lagging wall. The pressure diagrams for sand and clays developed by Peck and tieback anchor capacity curves from the Federal Highway Administration were used in the program. By varying the number and location of the tieback anchors, the wall design may be optimized for given soil conditions and wall requirements.