Why VighCon?

VighCon has many years of experience in dealing with Failed Retaining Wall and Paving Stone Systems.

At VighCon we have undergone specific industry that allows us to determine potential causes for failures and assess an approach to remediate any failure, including understanding where specific engineers and engineering will need to be involved.

Our main area of certifications and expertise are in the Segmental Precast Block Wall Systems and Interlock Paving System. Other systems and surfaces we have remediated also include:

Peace of mind from any Liability issues is paramount to any Homeowner, Homeowner association or property management group.

If you have a wall system or paver system that is failing, we can identify all potential causes and remediate them using our training and certifications in the current industry standards and practices to ensure it lasts like it is meant to.

Stone Repair
Failed Paver Patio
Failing Retaining Wall.jpg

What are the signs that a paving system is failing?

Unfortunately, when pavers are improperly installed the results can be disastrous — and maybe even get you sued. Here are some of the common signs that your job was installed poorly

Sunken areas indicate that the base is not holding up as well as it should. Most commonly, it happens when a contractor is either inexperienced or is rushing the job, and does not spend the time to compact the base well enough to hold up under expected traffic loads.

It can also happen when improper materials are used in the base. Specifically, when the base materials contain too high a percentage of fines or stone dust, it compromises the structure and can lead to settling.

The edges of paved areas require special treatment, because they do not have units supporting them on all sides. Any pressure put on them or on surrounding units tends to push them off the edge.

To correct this tendency, paver edges should be equipped with edge restraints — a detail which a surprising number of inexperienced contractors neglect to implement. Edges can also suffer from poor compaction of the base. A competent contractor will compact far enough beyond the footprint of the project to ensure proper compaction under the edges.

Pavers that shift out of place can be caused be a number of things. One very common cause is a base that is not deep enough. A contractor can save a lot on materials by skimping the base, but it will compromise the structure of the pavement.

Too much sand in the base can also cause pavers to shift or heave. Finally, if pavers not properly swept in and/or compacted after installation they can more easily shift out of place.

There are jobs where the bricks are just plain laid wrong. The patterns look uneven, or there are large gaps between pavers. This happens most often with inexperienced workers, but rushing a job can also bring careless results.

What are the signs that a retaining wall is failing?

Typically, a retaining wall does not experience a catastrophic failure without first showing signs that the wall is beginning to fail. Common signs that a wall is slowly failing include cracking in the wall, bulging or deflection of the face of the wall, and tilting of the wall. If a retaining wall shows any of these signs, it is likely time to have the wall evaluated.

Failed retaining walls can create a Liability Nightmare to Property owners, Home Owner Associations and Developers. What damages can be caused by the failure of a retaining wall?

A failing retaining wall often causes the soil behind the wall to begin moving as the wall moves. Movement of the soil held back by the wall will cause damage to any structure supported by that soil. For example, if a home sits back from the failing retaining wall, the movement in the retaining wall and the resulting movement in the soil will cause the foundation of that home to move. That foundation movement will then cause damage to the rest of the home. The homeowner may see cracks in drywall, bricks, or flooring and may notice that doors and windows in the home are difficult to open.

In the worst cases, where a failing retaining wall is not repaired and a catastrophic failure occurs, a structure behind the wall can completely lose the support of the soil below it and collapse. Such collapses not only can result in the destruction of the structure but can also injure the occupants and others in the area.

Slope stability is one of the key factors that need to consider in the retaining wall design. If there are is a slope stability issue, even other failure modes have higher factors of safety, we could not be able to avoid the failure of the retaining wall.

Slope Stability

The above figure clearly indicates the failure mode of the soil. So whether there retaining wall is stable or not, if it subject to this type of failure, the whole thing will collapse.

There will be a similar type of failure planes from the top to bottom of the wall. The factor of safety against each failure mode needs to be calculated. If the required factor of safety is meet by each failure plane, these types of retaining wall failures could not happen.

It could be difficult to do the analysis manually as it a long process and it will take time. If we use software like Slope W, we can find the minimum factor of safety very easily.

Due to the errors in the design calculations or errors made during the reinforcement detailing, inadequate reinforcement could be indicated in the drawing, which could result in retaining wall failures.

Even if the bar diameter and the spacing are correctly indicated in the drawings correctly, it may not be placed during the construction.

Further, it is required to provide shear links close to the base of the wall when the height of the increases. Incorrect calculation or construction error could avid placing these reinforcements will load retaining wall shear failures.

In general, weep holes are provided to avoid generating the pour of water pressure behind the retaining wall. They are placed in regular intervals to drain the water collected behind.

Poor construction or improper method of the installation could block the pipes could lead to an increase the pour water pressure. It will be considerable pressure on the retaining wall.

Depth to the foundation is very important in sloping ground. In addition, an increase in the depth of the foundation improves the stability even if it is constructed on flat ground.

When it is a sloping ground, there is a high chance of soil erosion. It could lead to exposing the foundation base reducing the resistance to overturning and sliding.

These actions could lead to failures in retaining walls.

If the foundation is placed on weak ground, creating a wall could settle when the soil pressure is applied on the wall.

Since the pressure under the foundation is not uniform due to the overturning, one side will settle more than the other side.

It will adversely affect the stability of the retaining wall and excessive deformation will occur.

Usually, retaining walls are designed for some surcharge loads depending on the design requirement.

The unanticipated load could lead to failure of the retaining wall. For example, one might construct a building close to the retaining wall. It will increase the pressure on the retaining wall.

As a result, retaining wall move laterally while rotating about the base. In addition, a new building constructed close to the retaining wall could collapse.

Clear reinforcement drawings need to be provided for the construction other than providing typical drawings.

Drawings indicating typical arrangement could not address the side condition accurately and the construction will be done incorrectly.

Providing incorrectly Geo-Grid positions, length and lapping the reinforcements where there are very high bending moments, etc. could lead to retaining wall failures.