Earth retention systems are required for support of excavations in urban areas and in locations, in general, where site constraints preclude sloped-back excavations. GZA’s approach to retaining system selection considers the technical and economical implications of the various retaining techniques available. Common wall systems include cantilevered and anchored walls, such as:

• Steel sheet-piles
• Soldier pile and lagging
• Slurry (diaphragm), reinforced and soldier pile and tremie concrete (SPTC)
• Secant pile (and tangent pile)
• Soil mix

Concrete diaphragm slurry walls and secant pile walls can be used to provide both temporary lateral earth support and as the permanent walls of the structure. The constructability and economics of each wall system must be evaluated for each project. Where protection of adjacent structures is a critical design consideration, GZA uses computer-aided finite element analyses to evaluate lateral deformations of wall system.  These analyses aid in selecting bracing locations that limit lateral deflection and allow for construction equipment access. This approach results in a more conomical design in comparison to using more conventional empirical earth pressure diagrams for wall and bracing design.

GZA routinely works with owners, engineers, and contractors starting with the selection of the wall system and then through design and construction. During construction, GZA provides construction monitoring to evaluate the performance of the system relative to stability and protection of buildings, utilities, and other facilities adjacent to the proposed construction.