WMATA Adjacent Construction Manual - Design of Temporary Excavations with DeepEX Software
The WMATA adjacent construction manual (2015), specifies how deep excavations adjacent to WMATA structures should be designed and constructed. When it comes to deep excavations WMATA guidelines have similarities to and differences vs. other accepted guidelines. DeepEX incorporates WMATA guidelines and standards as an independent analysis method.
For multiple supports WMATA utilizes an apparent earth pressure diagram with ordinates at 0.2H from the top and the bottom of the excavation. The maximum apparent pressure is calculated by applying a stiffness factor on the calculated active earth pressures that is either 1.25 or 1.5 depending on the adopted wall system. Minimum apparent pressures are either set at 25H or 29H depending on the wall type. The wall beam is analyzed with a continuous beam that is pinned at the excavation subgrade.
Figure 1: Soldier pile excavation supported by two levels of rakers, showing apparent earth pressures and bending moments with WMATA methods from DeepEX software
For cantilever walls or walls supported by one level of bracing WMATA recommends using a stiffness factor of 1.25 on active earth pressures. In all cases, a factor of 1.5 is used to reduce passive resisting earth pressures within the excavation.
Figure 2. Soldier pile excavation supported by two levels of tiebacks, showing apparent earth pressures and bending moments with WMATA methods from DeepEX software
With external surcharges WMATA utilizes specific approach for calculating their impact on an excavation. Generally only surcharges that fall within the WMATA influence zone are considered (set at 45 degrees two feet below the subgrade). These recommendations are taken into account by DeepEX automatically once WMATA methods for surcharges are selected.
WMATA also has some other recommendations regarding the spacing of supports, maximum cantilever excavation depth, and heel block resistance. These diagnostic capabilities will be included in future updates.
With the DeepEX wizard you can apply all the essential WMATA settins for deep excavation design!
Have piece of mind that your design is compliant with the WMATA adjacent construction manul specifications.
DeepEX Software implements several Structural and Geotechnical Design Codes
AASHTO LRFD, CALTRANS, EUROCODES 2, 3, 7, 8, ACI, BS, Australian Codes, Chinese Codes +more!
Solutions for Geotechnical Engineering Professionals:
DeepEX: Deep Excavations Design Software
DeepFND: Pile Foundations Design Software
HelixPile Helical Piles Design Software
