Buried Structures

The performance of tunnels, pipelines and other buried structures relies on their material and structural integrity and their ability to resist external forces. Exponent’s in-house geotechnical engineers and geologists, metallurgists, corrosion specialists and mechanical engineers, provide a multi-disciplinary approach to solving issues related to buried structures.

Buried structures (pipelines, culverts, conduits, tunnels, reservoirs and underground storage tanks) can be damaged by impacts, traffic and other structural loads, ground movements, scour, seismic activity and corrosion.  Damage caused to underground structures during excavation or construction is often dramatic and can occur for many reasons, including a failure to obtain clearance from a utility location service, inadequate marking and/or out-of-date plans.  Exceptional tire loads or loads imposed by nearby construction can damage underground structures by crushing or by causing separations at joints.  Improper bedding or backfill material can apply point loads on buried pipelines, causing damage. Unanticipated soil pressures can also have severe impacts on buried structures.  Ground movements, such as fill settlement, soil expansion or contraction, soil creep and landslide activity can also damage buried structures.  The scour of riverbeds during major flow events can remove lateral support for buried structures, making them susceptible to impacts from floating debris or bed load.  Seismic activity can trigger the types of ground movements already listed or can induce soil liquefaction, which may float buried structures out of the ground.

Corrosion is a chemical or electrochemical reaction that causes degradation of a material and can impact buried structures in a very significant way due to the environment that the material is exposed to. Often, these structures store and transport oil, gas, and other hazardous substances, which if released to the environment, can cause substantial damage. Severe corrosion of buried metal structures has led to explosions, loss of life, and massive environmental clean ups. In addition, leaking water pipes may cause or contribute to landslides and other earth movement.  A 2002 study estimated the direct cost of corrosion in the United States to be $276 billion annually, while the direct cost of corrosion associated with underground storage tanks alone was estimated to be $2.5 billion annually.


Exponent’s services include:

  • Surface and subsurface site inspection and sample collection 
  • Geotechnical and materials laboratory testing
  • Computer-aided engineering analysis 
  • Hydrologic analysis and scour analysis 
  • Creating and examining metallurgical mounts  
  • In-house Energy Dispersive Spectroscopy (EDS)  
  • In-house Scanning Electron Microscope (SEM)  
  • Analysis and interpretation of soil and water chemistry data  
  • Analysis of the cause(s) of corrosion