Basement Support Systems

Temporary and permanent support of basement excavations.

Increasing land value, strict parking ratio constraints and increasingly cost effective below ground construction techniques combine to make basement construction a viable option on a significant number of commercial and residential developments. 

Below ground construction requires temporary and permanent support of the basement excavation and if intersected ground water cut-off may also be required.  

The design of temporary and permanent retaining walls and support systems for basement construction requires detailed analysis, design, specification and monitoring of performance to ensure that stability is maintained and that deflections both during and post construction are within acceptable magnitudes.  Overall stability and wall/ground displacements are particularly critical where projects are located in an urban area with adjacent existing structures that may be susceptible to damage caused by settlement or lateral movement due to the basement excavation.  

CMW routinely undertakes specific site investigations and laboratory testing to develop a representative ground model and obtain representative soil parameters for design of basement support systems. These parameters allow us to calculate the magnitudes of static and seismically induced horizontal loads as well as the bending moments and shear stresses induced in the retaining walls. Detailed 2D or 3D finite element analysis of soil structure interaction, utilising specialist in-house and proprietary design software, enables development of reliable deflection and ground deformation predictions that can be utilised to assess and manage geotechnical risk associated with the basement construction works.

Having completed the ground modelling and detailed analysis CMW generally summarises the recommended retaining wall and associated support options, provides practical construction sequencing and details to enable cost effective and efficient basement construction.

With extensive experience in the analysis, design, construction and performance of cantilever, propped and/or anchored diaphragm walls, sheet pile walls, gravity walls, and contiguous, secant and soldier pile walls, the CMW team are able to provide efficient design solutions of schemes that are selected to suit project specific constraints.   

The above process is typically completed in close communication with the project structural engineer to ensure optimum solutions are developed and adopted that meet the project objectives with adequate risk management in place.

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