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Underground Engineering

We provide a host of design and consulting services for all phases of underground civil engineering projects, from feasibility studies to innovative design, and engineering support through construction. We work directly for government agencies and private sector owners, tunnel contractors, and as a specialty subconsultant to other engineering firms. Our leading-edge designs consider construction methods ranging from open-beam tunnel boring machines (TBMs) for hard rock tunnels, shielded rock machines, earth pressure balance and slurry machines for soft ground, and New Austrian Tunneling Method (NATM) techniques. We are recognized as one of the world’s acknowledged experts in the design of tunnels, deep shafts, temporary works, portal and slope stability, deep foundations, building protection measures, and ground improvement by grouting and dewatering. We have specialized education and practical hands-on field knowledge in the disciplines required for underground projects, including engineering geology, geotechnical engineering, rock mechanics, structural engineering, mining engineering, and construction contracting.  We also provide geotechnical investigation and characterization for underground projects. Finally, we understand the construction process at every level. We regularly lead multidisciplinary construction management teams and provide monitoring and tunnel inspection services.

Geotechnical Services

The first step to any underground project is understanding the ground conditions. Many of the risks associated with underground construction are related to ground conditions. Our geotechnical engineers and geologists can provide the range of services to take a project from conceptual planning, through design, and into construction. We are experts at identifying the risks of underground construction and working with owners, designers and contractors to effectively manage these risks.

We provide geotechnical expertise for planning and conducting geotechnical and geologic investigations for underground construction and interpreting the data to characterize subsurface conditions. We are experienced at preparing geotechnical data reports (GDRs) and geotechnical baseline reports (GBRs) to provide contractual packaging for anticipated ground behavior. We have expertise in the design of a variety of underground structures: Tunnels, Deep Excavations; Deep Foundations; Embankments on soft ground. We have experience in a wide variety of markets: Water Resources, Hydropower, Conveyance and Transportation.

Our geotechnical services do not stop at design; we have experience in providing design services during construction on behalf of owners. We frequently observe underground construction activities, documenting ground conditions and observing the work has been completed in accordance with the contract documents, and providing our expertise as differing site conditions arise. We can also provide geotechnical subject matter experts for dispute resolution.

Our geotechnical expertise includes:

  • Drilling program design, coordination, and permitting
  • Geotechnical Instrumentation
  • Unstable slope (both rock and soil) mapping, analyses, and mitigation design
  • GDR and GBR preparation and interpretation
  • Seismic hazard evaluation
  • Risk Assessment for underground construction
  • Deep Foundation Design and Construction
  • Deep Excavation Support Design and Construction
  • Embankments on Soft Ground
  • Soil-Structure Interaction Modeling
  • Geotechnical Engineering services for dispute resolution

Temporary Works Design

Temporary works design is an essential component during many heavy civil construction projects. Often, contractors must create temporary structures that adhere to exacting design and safety criteria — while at the same time being practical and cost-effective. We excel at providing temporary design services for deep shafts, dewatering, slope stabilization, support of in-place utilities, traffic decking and building underpinning.

Our temporary works support design services include a complete range of systems: cutter soil mix walls, soldier pile walls, sheet pile walls and cofferdams, internally braced shoring systems, tie-backs, diaphragm slurry walls, secant pile and tangent pile walls, soil mix walls, steel liner plate shafts, mechanically stabilized earth, soil nail walls, rock dowels, anchors, caissons, and ground freezing.

We are known internationally for our ability to provide effective construction engineering solutions that are sensitive to project economics, contractual responsibilities, and the physical realities of construction.

Cut & Cover Design

McMillen Jacobs Associates has extensive experience analyzing, designing, and constructing cut-and-cover structures in challenging ground conditions with complex site constraints. Our team of structural, civil, and geotechnical engineers gives us a comprehensive understanding of each project and helps us find best-for-project solutions.

We’ve made significant cut-and-cover design contributions to the Bay Area Rapid Transit system (BART), as well as similar work for the Washington Metropolitan Transit Agency (WMATA), the University and Northgate Link extensions in Seattle, Washington, and the Confederation LRT line in Ottawa, Ontario, Canada.

Our experience in this area dates all the way back to the 1970s, when the firm conducted a major U.S. government-funded research project and produced a three-volume report, “Cut and Cover Tunneling.” We created the guidelines used to select the most efficient construction methods.

Trenchless Design

Quality trenchless consulting goes beyond just specifying a construction method. Our experts understand the nuances and risks associated with trenchless technologies and ground conditions. We can provide comprehensive services — from preliminary and final design to construction management and support — that will assure your project’s success.

During the planning stages, we provide expertise in preliminary studies for alternatives analysis of open cut versus tunnel options, evaluations on the basis of constructability, construction costs, and schedule. We perform risk management by developing risk registers to assess design or construction phase mitigation measures that can be implemented to reduce or eliminate risk.

Our experts’ extensive experience covers the variety of trenchless construction technologies, including the latest developments in the field. We consult on all of the following trenchless methods:

  • Microtunneling
  • Horizontal Directional Drilling (HDD)
  • Tube Guided Boring
  • Direct Pipe Method
  • Pipe Bursting
  • Pipe Ramming
  • AXISTM Boring System
  • Auger Boring
  • Traditional Pipe Jacking

Asset Management/Tunnel Rehabilitation

Our asset management services focus on evaluating the remaining service life of underground facilities. We assess facility conditions, develop rehabilitation concepts, and provide preliminary cost estimates and schedule analysis for repairs. Through our expert inspection and rehabilitation, the longevity of a tunnel can be extended, whether as an alternative to new construction, to accommodate a change in usage, or to address tunnel deterioration and/or failure.