In order to prevent and repair damage to underground infrastructure, it is helpful to understand the underlying causes of this damage. The bottom line (no pun intended!) is that subterranean pipes are sporadically if not constantly subjected to a wide variety of physical, chemical, biological, and/or biochemical stresses. These stresses can be engendered or aggravated by the ways in which the underground infrastructure in question has been planned, constructed, and maintained. They are also profoundly influenced and affected by the materials that were used to create this infrastructure and this infrastructure’s intended purpose and duration of use.

The Specific Origins of Specific Types of Damage

In order to more effectively list and examine the underlying reasons for underground infrastructure damage, it will be useful categorize them according to the specific damage that they tend to cause. For simplicity’s sake, we will begin with the damage that is typically most obvious.

Leaks

Although leaking become obvious when adequate amounts of water fail to enter or leave a specific structure, testing is often necessary to detect smaller leaks. There are numerous causes for the occurrence of leaks. First and foremost, leaks become far more common when underground infrastructure construction professionals fail to comply with industry regulations, guidelines, and material standards in the following categories:

  • Planning
  • Workmanship
  • Operation
  • Component and Material Selection

Leaks also commonly arise as a result of natural or accelerated material ageing, as well as traumatic damage that might arise from…

  • Mechanical Wear
  • Positional Deviation
  • Corrosion
  • Deformation
  • Pipe Cracks, Breakage, and/or Collapse

For more information on each of these common causes of damage, read on!

Mechanical Wear

Defined as the continuing loss of material from the surface of a solid object due to the contact and relative movement of a solid, fluid, or gaseous substance, mechanical wear causes substantial damage to underground infrastructure over time. In the case of pipes, the wear process takes place on the pipe’s inner surface and can be measured as the general rate of wear (absolute value) or the relative rate of wear (millimeter deductions per load application).

The main types of mechanical wear are…

  • Scouring wear (due to flowing erosive active media)
  • Impingement erosion (due to striking fluid drops)
  • Erosion by cavitation (due to surface shattering as a result of microjets caused by cavitation)
  • Fluid erosion (due to the movement of flowing fluid)

Positional Deviation

Positional deviation occurs when underground infrastructure experiences an unplanned deviation from its nominal position as determined by planning and implemented during the construction process. This deviation can occur in the…

  • Vertical direction
  • Horizontal direction
  • Longitudinal direction

Possible causes of positional deviations include the following:

  • Incorrect planning and construction work
  • Settling
  • Load changes
  • Hydro-geological changes
  • Subsidence and earthquakes
  • Leaks

These problems can be engendered or aggravated by conditions such as the influx of groundwater and the occurrence of strong traffic loads.

Flow Obstacles

Flow obstacles are defined as any object or material that lays in the cross section of a pipe. These obstacles present tremendous problems when liquid can no longer flow unimpeded within the pipe’s interior. The most common flow obstacles that underground infrastructure construction professionals encounter arise as a result of…

  • Hardened Depositing/Incrustation – The result of internal materials that have settled under the force of gravity, deposits must be regularly removed or they will become more and more securely affixed over time.
  • Man-made Flow Obstacles – These obstacles may include poles and other construction components that enter or pass through underground infrastructure.
  • The Ingress of Roots – The gradual persistence of the growing tree root can cause catastrophic damage to pipes. Since the 1950s, however, industry standards have demanded that all piping materials (including sealing media, gasket rings, and complete pipe joints) stay abreast of evolving root-resistance technology.

Corrosion

A reaction between a material and its surrounding environment that causes a measurable change in that material, corrosion can seriously impair or even destroy the functionality of underground infrastructure components or a complete underground infrastructure system. The extent of corrosion damage depends primarily upon the aggressiveness of the corrosion medium and the quality of the materials that are affected. Elements that influence the aggressiveness of a given corrosive medium include temperature and relative concentration.

In general, corrosion occurs as a result of material incompatibility among various underground infrastructure elements such as pipes, fittings, sealing materials, and gasket rings. It can also arise in cement-bound building projects both internally and externally. All forms of corrosion can be restricted to limited and localized areas, spread evenly over entire sections of underground infrastructure, or distributed unevenly over an underground infrastructure cross section.

Cracks, Breaks, and Collapse

The causes of pipe cracks, breaks, and collapse are closely tied to the type of pipe at hand and its specific purpose and material makeup. One cause can result in several different cracks while one crack can have several different causes. Most prevalent in more ridged forms of underground infrastructure, cracks can obviously be regarded as precursors to more catastrophic forms of damage.

Important things to consider when determining the causes of various cracks include the following:

  • Crack alteration over time. (Is the crack stable, or is it still propagating?)
  • The depth of the crack. (Is the crack superficial or does it extend throughout the wall of the component?)
  • The course of the crack. (Is the crack longitudinal or latitudinal? What force might be acting upon it?)
  • Mutual displacement of the edges of the crack. (What is occurring at the edges of the crack? What information does this provide about the force acting upon it and the component’s resulting danger of failure?)

Cracks can also result in the wake of operational and construction anomalies such as…

  • Failure to adhere to accepted standards and regulations
  • Damage to underground infrastructure components during storage, transport, laying, bedding, backfilling, and/or compacting.

For More Information

To find out more about the underlying causes of and solutions to underground infrastructure damage, contact the subsurface utility engineering (SUE) professionals at Underground Services – SoftDig today. Call us at (610) 738-8762 or use our request an estimate form. Feel free to also take a look at our portfolio of past work. We look forward to helping you!

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