In road infrastructure projects and operating platforms, the presence of a high water table in the subgrade represents one of the most critical conditions from the geotechnical point of view. This situation not only affects the bearing capacity of the soil, but also alters its stress-strain behavior due to the direct interaction between water and the soil matrix.

More than a structural problem, this is a phenomenon hydraulic-geotechnical, where water control is crucial to ensure system performance. In this context, the systems of subdrainage with geosynthetics have established themselves as an efficient, reliable and technically superior solution compared to traditional alternatives.

What does the water table in the subgrade imply?

The water table corresponds to the zone where the soil pores are completely saturated. When this level coincides with the subgrade level or is close to the surface, unfavorable conditions are generated for the support of the pavement structure.

From a soil mechanics point of view, a high water table represents:

  • decrease in shear strength
  • increased susceptibility to deformation
  • loss of rigidity
  • unstable response during construction

In the long term, this phenomenon may result in:

  • progressive loss of bearing capacity
  • permanent deformations
  • accelerated pavement deterioration

Hydraulic system control

Since the origin of the problem is hydraulic, the solution must focus on controlling the water within the soil mass.

This involves:

  • Capturing groundwater, reducing the water table elevation to reduce pore pressure in the subgrade
  • Facilitate their evacuation in a controlled manner

For this purpose, subdrainage systems designed to operate continuously within the soil and maintain controlled moisture conditions are implemented.

Subdrainage systems with geosynthetics

Modern subdrainage systems incorporate drainage geocomposites, as PERMADRAIN, known as geodrenes.

They are made up of three main components:

  • Superior nonwoven geotextile
  • HDPE geonet type drainage core
  • Bottom nonwoven geotextile

This assembly configures a high hydraulic capacity system, capable of capturing and transporting water efficiently even under confinement.

HDPE perforated pipes

Perforated HDPE pipes, such as DRAINPIPE, They complement the underdrainage system by acting as flow collectors.

Its main function is:

  • to receive the water captured by the geodrenes
  • to discharge points
  • maintain a continuous flow within the system

These pipes have:

  • high mechanical strength
  • high durability
  • compatibility with filter enclosures

This ensures its long-term performance.

Advantages over traditional systems

Traditional systems, such as the French drains, The filtering system consists of trenches filled with granular filtering material.

Although they have been widely used, they have important limitations:

  • dependence on the quality of the filter material
  • risk of clogging due to migration of fines
  • increased excavation volume
  • installation variability

In contrast, geosynthetic systems offer:

  • controlled filtration by means of geotextiles
  • high hydraulic capacity in a smaller space
  • faster and smoother installation
  • less susceptibility to clogging

This makes them a more efficient alternative from a technical and constructive point of view.

Conclusion

The presence of a high water table in the subrasante is a critical condition that directly affects its stability and performance.

Water control should not only be addressed through structural solutions, but also through proper water management.

The systems of subdrain with geosynthetics, The use of planar geodrains and perforated HDPE pipes allows water to be efficiently captured, conveyed and evacuated.

This:

  • reduces pore pressures
  • improves effective effort
  • stabilizes soil conditions

Compared to traditional solutions such as French drains, they represent a more efficient and durable alternative, consolidating themselves as a key practice in modern infrastructure.

Hydraulic management has been extensively documented by the Federal Highway Administration (FHWA).