Article Post

Construction Vibration Damage Claims

September 14, 2022

Vibrations can originate from various sources, and the damage can range from purely cosmetic to structural. Vibration damage has no unique visual signature, making it harder to detect. It often looks very similar to the type of damage commonly found in old buildings, ranging from shrinkage, and thermal expansion, to settlement. When investigating vibration damage claims, the expert analysis goes beyond visual examination.

The science of vibration damage claims

How vibrations cause damage

Figure 1: An illustration of vibration damage.

Vibration damage is predominantly a 3-step process. First, vibrations are generated at some source. Next, those vibrations travel and dissipate through the air and the ground. Finally, structures close to the source receive the vibrations and react in different ways:

1. The building may start to sway back and forth 

Figure 2: A slightly exaggerated illustration of a back-and-forth building motion.

The ground moves, followed by the building. This type of motion is more from an earthquake type of ground vibration rather than something like road construction. Nonetheless, this type of motion can occur and would be a direct type of effect that vibration has on buildings.

2. The walls or floors may vibrate like a drum skin

Figure 3: An illustration of floor and wall vibrations.

The floor starts moving up and down, or the walls start moving in and out of a plane. This is typically what happens to nearby houses when construction activities cause vibrations.

1. The soil under the footings may consolidate.

Figure 4: Loose, granular soil before (left) and after (right) vibration.

This is often an indirect effect and can be quite damaging. A loose, granular type of soil, like sand, has a lot of voids between the particles. As the vibration energy shakes these particles, they fall into more compact configurations. As a result, the ground level at the surface will drop, and anything sitting on it will also drop. Consequently, the house will experience vibration, resulting in settlement and associated damage.

Vibration damage

Figure 5: A vibration damage scale.

There’s a huge range of vibration damage, starting from the lowest intensity and gradually progressing into intense vibrations that can damage unreinforced concrete and engineered structures.

Figure 6: An example of cosmetic damage.

Types of cosmetic damage range from drywall pop to plaster becoming damaged. The plaster relies on keying action, and those keys degrade over time. However, vibration will also help break them.

Figure 7: A masonry wall before (left) and after (right) construction vibration.

The masonry shed in figure 7 was slated to be demolished. It was old and needed to be better maintained. Therefore, the company doing the roadwork outside decided to run an experiment. They ran the roller shown on the left at maximum vibration settings, very close to the building. The masonry sustained damage two minutes later. Several of the bricks had fallen away. This indicates that very tense vibrations can cause damage even to structural materials.

Factors affecting vibration damage

  • The intensity of the source vibrations
  • Duration of exposure
  • Distance from the source
  • The type of structure: Buildings constructed with lighter, softer materials – such as wood-framed houses or older masonry buildings – would sustain higher levels of damage compared to engineered structures at the same level of intensity.
  • Soil characteristics: The energy of vibration travels through air or the ground. However, most of it will travel through the ground. Therefore, the soil type plays a great role in determining how much energy the structure receives. Under intense vibration, granular soil will vibrate until some of the voids are eliminated. The particles start to interlock more and eliminate some of the air. As a result, the ground will drop slightly. Anything constructed above that ground will be impacted, resulting in settlement. However, there’s no distinguishable difference between soil settlement caused by vibration and that caused by other damages.

Common causes of vibration claims

  • Traffic-related vibration

These include rail and vehicular traffic. These vibrations occur in structures close to rail lines or the main road frequented by heavy trucks. This would fall under long-term exposure. Under those circumstances, some vibration damage to older buildings and wood-framed residential houses can be seen.

  • Jackhammering

The asphalt layer in our roads deteriorates quickly owing to the harsh Canadian weather. Consequently, our roads need repair almost every summer. We use jackhammering to get rid of the impacted sections of the asphalt layer, sometimes to remove part of the concrete walkways to make room for the new one. The intensity of vibrations that come out of jackhammering is especially high, especially for nearby residents. The vibration can impact buildings close to such projects.

  • Bulldozing

Construction is booming in the greater Toronto area and Canada as a whole, with new neighborhoods built almost every day. However, with new construction comes the need for new roads. Bulldozing the ground around new construction is not uncommon. This type of heavy equipment could generate enough intentional vibrations to cause some damage to residential construction.

  • Pavement milling

The piece of equipment used for pavement milling grinds and chews the old asphalt layer. The asphalt is loaded from the rear of the equipment into trucks for removal and to make room for a new layer of asphalt. This grinding and chewing of the existing pavement create a great deal of vibration. Resurfacing of roads happens in already developed, well-established neighbourhoods. As such, there is no avoidance of the vibration, which could cause damage to buildings.

  • Vibratory compaction 

This is also used in road construction. Each asphalt layer of the road has a substrate supporting it underneath. A vibratory compaction machine is used to compact this layer to make it as sound as possible to support the asphalt layer and the traffic above. The use of this heavy equipment in road construction generates vibration. Because these are typically larger scale projects that are recognized beforehand, the contractor is usually asked to engage the services of professional engineers to do a vibration damage assessment.

  • Pile driving

When you have steel members or precast concrete piles, you use a huge machine that drops a heavy weight on top of this column-like member to drive it to the depth required. This is often necessary when constructing bridges or retaining walls around large facilities. The piles provide support for the bridges and retaining walls.

  • Other sources – gas explosions and blasting

We have seen vibration damage due to unfortunate incidents such as gas explosions. Although they are very infrequent, we have seen at least two major events in our area over the last two years. Blasting is another source of vibration. Blasting usually relates to mining and preparation for the new highway construction. Usually, it’s in less populated areas.

Measuring and monitoring vibrations

Peak particle velocity (PPV)

The equipment used to measure PPV is relatively simple. We use accelerometers, geophones, and vibration meters. Accelerometers are typically used to measure earthquake intensity. However, there are similarities between earthquake phenomena and vibration excitation resulting from construction.

Vibration thresholds

Once we determine the PPV, we can check this number against the existing standards or guidelines for the threshold to cause vibration damage.

Table 1: Vibration damage thresholds recommended by the U.S. Federal Transportation Agency.

Occupants would start to feel vibrations when the PPV value reaches 0.5 mm/s. However, five mm/s is the threshold required to cause any damage to non-engineered types of structures.

We don’t have a Canadian standard to consult with regard to vibration. The City of Toronto has its guideline, but we typically consult the British, German, and Swiss Standards, which have similar threshold values for vibration that would cause damage to certain types of structures.

The investigative process of vibration damage

The first step is a review of all available information, including the construction project details. This involves a review of the activity logs to determine the scope of the project, the schedule, the equipment used, and activities completed. Geotechnical reports, if available, can help identify the local soil conditions.

On large-scale projects, there might be a pre-construction property survey. As part of their due diligence, the contractors might have surveyed nearby homes and documented damage that was present before the construction began.

There might also be a pre-construction vibration assessment study on large-scale projects. If that’s available, we look at the results of that study. These results tell us the identified risks, recommendations to mitigate any risks, and available site-specific vibration data. All this information improves the precision and accuracy of our analysis.

Next, we examine the site and interview occupants. We take a look at the severity of the damage, locations of damage,  and the general pattern of the damage. We also examine the site to identify potential pre-existing conditions or other causes that could have been a more likely explanation for the damage.

We would interview occupants to get a feel of their experience. We look for their description of the vibration and any observations they had during the incident. They might even know what equipment was used and have specific days written down worse than others. We can compare that information to the foreman’s logs and equipment list if we have that information. Occupants may also have before and after photos. So, we can see the progression of damage.

We use all this information to carry out vibration analysis and try to establish the likely zone of influence for the different construction activities in the area. This serves as another tool to help us determine whether it’s plausible that vibrations exceeded our damage threshold.

The zone of influence

Figure 8: An example of a zone of influence.

The zone of influence is an area around a source where the vibrations would be expected to be higher than the threshold level. The red zone in figure 8 might indicate the damage threshold, and the yellow zone might be our disturbance threshold.

The yellow zone reaches the houses, whereas the red zone barely leaves the roadway. Once we’ve estimated our zone of influence, we can confirm that some homeowners would feel vibrations in their homes because they are within the zone of influence for disturbance. However, the zone of influence for damage is limited to the roadway. This means we wouldn’t expect to see any damage to the houses.

Example

A homeowner reported strong vibrations and cracking in the finishes in their house. There was a new service road being constructed approximately 50 feet away. The construction went on all summer, and the local soil was hard clay.

Figure 9: Some of the damage observed.

We came up with a PPV range to determine the zone of influence.

Figure 10: The zone of influence (left) and the vibratory roller (right).

We determined that the strongest source of vibration was the vibratory roller. Based on our available information, we estimated that the range of likely PPV experienced at the house was 7 – 10 mm/s.

As shown in figure 10, even our low estimate reaches the house, and the highest covers a larger area. The results of this analysis indicated that the vibration intensity may have been above the threshold for damage. This means it’s plausible that vibrations indeed caused some of the damage observed.

What information do we need for our investigation? 

  • Equipment list
  • Civil engineering project drawings
  • Activity logs
  • Geotechnical reports. In lieu of this, we might have to do a site investigation or refer to older geotechnical reports if they’re available for other projects in a similar area.
  • Pre-construction survey,
  • Pre-construction vibration study on large-scale projects
  • Vibration monitoring

All this information would be available from the contractor doing the work. So, if you’re the adjuster on the contractor side, that’s the information you want to give to your consultant. If you are on the homeowner side, this is the information you want to ask for immediately.