Impermeabilización de túnel "Los Bueyes"

Study cases
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Tunnel waterproofing "Los Bueyes"

Tunnel waterproofing "Los Bueyes"

Introduction

For a country to develop it requires infrastructure, which is why communication and transportation routes are of vital importance. One of the main problems in Mexico is its irregular orography in some regions, for which, when designing the roads, the design and construction of tunnels and viaducts becomes mandatory to overcome these obstacles, increase user safety and shorten times. of movement of people and merchandise. This case study explains the challenges involved in waterproofing the “Los Bueyes” tunnel, located in Nayarit, Mexico.

Trouble

The construction of tunnels involves very complex processes, in which their correct waterproofing and drainage must be considered to protect the work from the problems generated by water.
In any underground work, internal runoff is an important aspect to deal with. In the case of tunnels, water infiltrates from all sides, reaching the vault of the section where the excavation is located. If these problems are not solved correctly, they can cause problems at the beginning in the construction processes themselves, and at the end of the tunnel construction by reducing the life time for which it was designed.

The challenge

The most important challenge was to ensure that the tunnel was fully waterproofed in the shortest time possible so as not to delay the construction processes after waterproofing. Which requires a correct selection of materials and system, all the experience of the technical specialists, as well as careful planning and supervision of the work.

Solution

It is proposed to waterproof the tunnel with a special PVC-p geomembrane for underground works, together with a non-woven polypropylene geotextile. This waterproofing system is quick to install and meets all the international standard requirements necessary to ensure that the tunnel is perfectly protected from water seepage.
Both the geomembrane and the non-woven geotextile are extremely flexible materials that perfectly conform to the irregularities of the tunnel surface, from the gables to the vault.
The non-woven geotextile protects the geomembrane from possible punctures, while the geomembrane acts as an impermeable barrier that prevents the passage of water from runoff and groundwater and leads it to the drainage points.

Process

The assembly car is assembled, which covers the entire tunnel section with lifting machines in the process.
The geotextile is installed in sections along the tunnel section: the geotextile works as a protection for the geomembrane and as a water draining conductor throughout the section. Installation is done with impact fasteners (nail and detonator). The nails have a PVC-p rosette, which is subsequently welded with the geomembrane for temporary support, awaiting the final finish.
The geomembrane is placed in 2 m cloths throughout the tunnel section and it is thermofused to the PVC-p rosettes that were specifically placed on the geotextile.
When two geomembrane panels are placed, there must be a space in which they overlap each other; This section is called an overlap or overlap. In this area, the thermofusion is carried out so that the cloths of the material join and remain as a single layer, guaranteeing the impermeability of the covered surface.
This process is repeated throughout the tunnel, making movements of the assembly cart to advance and place the material in a new area, the next section of the tunnel to be waterproofed.
In the case of the Los Bueyes Tunnel, the same waterproofing process was carried out on the outer walls of the tunnel exit points, also known as “false tunnels” or “false tunnel”.
When the material is thermofused, airtightness tests are carried out on the 100% of the overlaps (joints between panels), as a quality control to guarantee that the thermofusion has been carried out correctly and the system is watertight.

The results

The project was completed in a timely manner. The result of this solution is a reliable and controlled waterproofing, whose easy application translates into savings in money, in execution times and in future maintenance.

conclusion

Carrying out tunnel waterproofing by implementing PVC-p geomembrane and non-woven geotextile, following international regulations, saves time and operating costs, in addition to guaranteeing 100% waterproofing of this type of infrastructure works.

Technical aspects

Location: Nayarit, Mexico.
Design: GEOSA, Geology and Underground Works.
Execution: GEO & GEO Infrastructures.
Products: PVC Geomembrane TN Logicbase V SL 1.5 MM Tunnels Signa Layer yellow-black | Logrotex G705 PPT Nonwoven Geotextile.
Geosynthetic manufacturer: Technonicol (TN México) and Logrotex SA.