Why Are Vertical Drains Important?

vertical drains

Geosynthetics and woven geotextile materials are heavily used in Malaysia as well as other countries for different purposes like constructing roads, especially highways and other heavily-trafficked areas. 

In addition, materials like these are used to construct other types of structures like parking lots, footpaths and roads. The purpose of PVD installation is to improve the quality of the constructed roads.

Before getting into the details of the benefits of geosynthetic material for road construction and vertical drains, let’s get familiar with some of the basics of vertical drains.


Why is a Vertical Drain Necessary?

When roads, footpaths, parking lots or forest paths are constructed over deep soft soil, it can lead to massive settlements accumulating over an extended period of time. 

To speed up this process, vertical drains are installed nearby to provide an alternative route through which pore water can be drained rapidly. The overall stability of the embankment improves when the pore water pressure is reduced via vertical drains.

Traditional Technique of Installing Vertical Drains

Vertical drains contain a permeable plastic core that is wrapped in a filter member. It also has a hollow mandrel for easy installation. 

A mast is used to push the mandrel into the soft soil. The mandrel is taken out and the drain is left in the ground. Similarly, another drain is inserted into the next position.

Installing vertical drains and using geosynthetic material benefits the roads in the following ways:

 

1. Improves Bearing Capacity

A strong support system is required while constructing roads in heavily trafficked areas, for example, parking spaces. These structures must have a maximum bearing capacity. 

For this purpose, geogrids are installed in the middle of the base course and the subsoil. Geogrids are made up of flat bars and have durable welded junctions that are able to withstand a massive amount of pressure.

The soil is able to interlock with the efficiently designed geogrids, which develops a strong bond. Due to this interlocking, a horizontal force transfer occurs which dramatically expands the soil’s bearing capacity. 

Even with low elongation, a significant amount of force is absorbed by the geogrids, improving the capacity.

If a structure needs a specific bearing capacity value, it can be achieved by adding multiple geogrids. It is a very cost-efficient way because you do not have to spend on expensive soil exchanges.

Geogrids and non-woven geotextile material are extensively used in Malaysian construction projects to act as an excellent filter. They impede the migration of small particles into the base course.

Many suppliers also combine geogrids and woven geotextile to create a combined product that will support the construction and improve bearing capacity. Multiple layers of geogrids should be used in areas where the soil is extremely soft.

 

2. Reduces Rutting

Constructing unpaved roads on soft subsoil can cause rutting and intermixing of construction material with the subsoil. 

It is very common while building forest paths and other temporary construction roads. Rutting can be avoided, or at least minimized, by installing vertical drains and geogrids. 

Geosynthetic materials enhance the load distribution, leading to minimum rutting and soil intermixing. 

Since there are different types of geogrids available, the developers have to choose the best one according to the project’s specific requirements and soil conditions at the construction site.

 

3. Elongation & Force Absorption

Reinforcement material with low elongation attributes must be used to properly support the road. 

Normally, geogrids have to manufactured elongation, which makes them a suitable material for road construction

Reinforcement bars are welded at the junctions to maintain a balanced force absorption between 2% to 5% elongation.

 

4. Quick Installation

With proper planning and scheduling, vertical drains can be installed quickly and efficiently. 

The installation process becomes reliable and smooth when a high-quality material is used. It makes the PVD installation easy and rapid. 

Moreover, the traditional reinforcement bars can be vulnerable to high stresses during construction, but geosynthetic materials are thick and robust, which makes them fairly resistant to high pressure and heavy loads.

 

5. Overall Benefits

Vertical drains can enhance the settlement rate by up to 90% in very soft soils. Moreover, such material is beneficial and economical to use in reclamation projects as well. 

The quick settlement increases the speed of the entire construction or reclamation project and hence saves overall cost.

 

The Bottom Line

Geotextile materials, especially woven geotextiles and geogrids, have a great number of advantages in road construction, making them essential for the construction of heavily-trafficked areas. 

To improve bearing capacity, reduce rutting and avoid extremely expensive soil excavation, geosynthetics are used for quick and reliable construction. 

In addition, geosynthetics and vertical drains are much more cost-efficient than traditional construction techniques. 

For more information, feel free to get in touch with us.