Construction Vibration Monitoring: Key Steps to Maximise Your Operations
Discover all the key steps in this comprehensive guide developed by our experts to effective vibration monitoring and management on construction sites, ensuring the success of your project!
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Vibration Monitoring on Construction Sites: A Practical Guide
For Construction Estimators and Project Managers
Construction vibration monitoring is an essential and necessary practice in the construction industry. Such factors include, but are not limited to, protecting sensitive equipment and areas within close proximity to construction operations, preventing damage to adjacent buildings, structures and buried infrastructure, and complying with regulatory standards whether for structure integrity or to protect sensitive equipment.
However, necessary key steps for adequate vibration control are often omitted, neglected, and/or downplayed in project proposals. By not considering the necessary key steps for ensuring control, you may be unknowingly putting your project at risk for financial and productive repercussions. Exceeding regulatory limits can result in halting all operations until mitigation measures are put in place.
Soft dB's experts specialize in vibration and are dedicated to your project's success. This guide was developed specifically with construction estimators and project managers in mind. In this guide, you will find an overview of a step-by-step process of an effective vibration control program, aimed at contributing to the success of your project: 1) Conduct Baseline Vibration Measurements, 2) Pre-and Post-Construction Surveys, 3) Ground Vibration Management Program, 4) Vibration Monitoring Plan, and 5) Implementation of the Vibration Monitoring Plan.
First things first, before delving into the step-by-step process, let's clarify what construction vibration monitoring entails.
What Is Construction Vibration Monitoring?
Construction vibration monitoring is a cost-effective method used to assess the vibration levels caused by construction activities and ensure that they remain within safe limits in function of the type of structure, the duration of vibration or the sensitivy of various type of equipment. It involves monitoring the transfer of vibrations from the source through various components, such as soil or steel structures, to ensure that they do not cause damage adjacent properties, including critical facilities like a hospital.
Conduct Baseline Vibration Velocity Measurements
The first step of an effective vibration monitoring program is to conduct baseline measurements, prior to the start of construction work, to collect background vibration levels.
This captures the initial state and provides reference points for comparison throughout the project. The monitoring process measures key parameters such as velocity amplitude and frequency, which are compared to various regulatory standards.
To achieve these reference points, baseline data is gathered by measuring existing vibration levels in the soil or at the structure and surrounding area. This includes measuring both horizontal and vertical vibrations, providing a clear picture of the background levels and the potential impact of construction activities on structures. Geophones or MEMS are generally used to monitor vibrations. The data collected is logged, and reports are generated to monitor vibration duration and any spikes occuring before construction starts.
To ensure this baseline is as precise and actionable as possible, seismographs are installed close to sensitive areas of the site. These devices measure vibration levels, establishing a baseline and determining the precise vibration environment before construction starts. This approach ensures a clear understanding of the vibration environment and helps develop a customized plan to manage vibrations throughout the project.
Why Is It Important to Take Baseline Vibration Levels?
Baseline vibration measurements are crucial for several practical reasons: to protect sensitive equipment, ensure structural integrity, critically assess project specifications which are generally defined based on standards where geophones measure vibrations levels and frequency and specific maximum horizontal, longitudinal and vertical velorcities, and safeguard against potential complaints.
To Protect Sensitive Equipment
By measuring and establishing a pre-construction baseline value, you can determine the baseline vibration level that nearby sensitive equipment and instruments, such as laboratories and server rooms, have already been subjected to. This enables you to establish the maximum vibratory trigger, in order to avoid any risks of potential damage to equipment and/or instruments, as well as the need to recalibrate instruments in the process.
To Protect Structures and Buildings
Generating excessive vibration can also lead to structural damage. By conducting vibration baseline prior to starting construction operations, you can be informed of the vibration levels to which structures have already been exposed, and can take the necessary steps to comply with them, thus preventing the risk of structural damage.
What Vibration Levels Cause Damage?
In order to protect structure, understanding the broader implications of vibration levels is particularly important in construction.
Depending on the standard, research indicates that, at low frequency, vibrations velocities exceeding a few millimeters per second can begin to cause structural damage in buildings, especially older ones. At these levels, sensitive equipment can also become affected, leading to malfunctions and costly repairs. Furthermore, higher vibration velocity can impact a range of structures, including concrete and masonry, potentially resulting in cracks or other types of deterioration over time.
Many construction projects involve the use of heavy machinery that generates significant vibrations directly affecting to nearby structures. These vibrations can trigger a range of issues, particularly when the levels recorded exceed safe thresholds. Research shows that, depending on frequency potentially damaging effects can occur when certain frequencies and amplitudes are reached, causing structural fatigue in concrete and other materials. As each project begins, it is crucial to monitor vibration signal levels continuously to ensure the well-being of surrounding environments.
Ensure to Remain Critical of the Specifications in the Estimate, Review the Threshold Exceedances as Needed, and Prevent Any Unnecessary Stop-Work Interruptions
Here is an example to illustrate this point: Let’s say, a construction site is located next to, or inside the same building, as an art gallery or a museum displaying articles of high value and fragility.
To protect the integrity of the articles, vibration requirements in the vicinity tend to be extremely strict, and are often limited to less than a millimeter per second. However, other variables are important to note when establishing the appropriate threshold for any construction project. In fact, its quite possible that the actual vibration levels that transfer in the gallery/museum are higher than those outlined in the specifications! Thus, detailed and specialized analysis of the structure, source and transfer paths of vibrations velocities is necessary.
Articles that have already been subjected to certain vibration levels may not actually require imposing extremely stringent requirements in specifications. Hence the importance of taking vibration measurements before starting construction — so that the vibratory limits in the proposal are more representative of the affected area and structure.
In fact, if the project requirements specify “little to no vibration” when there are already vibrations present in the environment, not accounting for this may unnecessarily restrict your activities, thereby reducing your productivity, increasing your lead times, and ultimately underestimate your actual construction costs.
If the vibration already present in the environment exceeds the specification limits (as set in the proposal), every reported exceedance could potentially bring your business operations to a halt, even if your operations are not the cause.
Establishing a baseline and having these vibration measurements on hand will enable you to take a critical approach to the specification requirements. By re-evaluating the established vibration limits, and adjusting the threshold accordingly, your construction activity will be able to operate more efficiently by maximizing your production potential.
To Protect You in the Event of Complaints and Damage Claims, and to Respect Compliance
Complaints are a critical element to consider when managing construction activities, particularly when the operations can lead to any form of disruption and/or change to an established community. While some may be welcoming and relatively unbothered by the new developments, some will be vigilant ensuring that any perceived increase in vibration will be voiced. Having a proactive plan in place for vibration and/or noise, greatly reduces any reactionary costs that may be incurred due to these complaints.
For example, if a resident lodged a complaint against a project claiming that the construction site is generating too much vibration (and/or noise), operations might need to cease until proven otherwise. Without any reference (baseline) and monitoring to show the existing values, it will be difficult to prove that vibrations have remained compliant with regulatory thresholds.
On the other hand, if baseline measurements were conducted and had demonstrated a pre-construction background vibration levels in the environment are high (prior to construction activities), and a vibration monitor was present to demonstrate that vibrations caused by construction activities are within pre-construction levels, then such a complaint would be classified as unfounded and operations could continue as planned — not incurring any production or financial repercussions, as a result of being proactive.
Establishing an pre-construction baseline by conducting preliminary vibration measurements is a proactive approach to ensure that you’ve covered all your bases, to “green light” your construction operations, ultimately setting your project up for success.
Pre-Construction and Post-Construction Surveys
The second key step for vibration control management is the pre-construction survey, which involves the commissioning of a specialist to go out into the field to evaluate/inspect existing cracks, take photos, and document the overall condition of the structures surrounding the construction site — before and after construction. These inspections account for the physical aspect of the assessment process of structures, providing the necessary documentation should any change in the environment be brought into question, at any time.
The Importance of Inspections
These inspections account for the physical aspect of the assessment process of structures, providing the necessary documentation should any change in the environment be brought into question, at any time.
To protect the contractor in the event of recourse
In the absence of a preliminary or post-construction inspections, any cracks or visible damages that appear to structure, or were discovered anytime throughout the duration of the construction phase, will be tremendously difficult for the contractor to prove actual causality - whether their operations were/were not responsible for such damage.
Having the necessary documentation can protect the contractor from being liable for such claims, thus avoiding the heavy financial repercussions of having to correct any damages, even if the damage was not actual caused by the construction operations.
To minimize site operation stoppages
In the event that a resident files a complaint of a damage to their property (at any point during construction operation), not having the necessary documentation to prove causality, might result in a cease of operations until the investigations have taken place.
However, if you can produce documents to show that the damage was already there, activities should likely be free to continue.
Just as preliminary vibratory measurements establish a baseline, conducting a physical inspection (and documenting the preexisting conditions of the site and structures), can dramatically reduce your risks of incurring any financial or productive repercussions.
Furthermore, conducting a post inspection, allows for a before and after construction comparison. Evidence showing that the initial damage conditions have not been changed, also provides protection in the event that a resident files a complaint, even after the project has been closed off.
The Threshold of Sensitivity at Which Humans Feel Vibration Is Considerably Lower Than the Threshold Causing Structural Damage
It is important to note that depending on frequency, the human body can generally feel vibrations around 0.2 mm/s, while more restrictive standards for protecting the integrity of very sensitive structures is 3 mm/s in frequencies between 1 and 10 Hz (according to DIN4150-3, category 3).
This shows the human body can sense vibration much lower than, well before, any physical structures are at risk for damage.
This means that residents living close to a construction site may feel/sense the vibration with the perception of it being excessive, even though the actual levels are lower than a threshold capable of causing structural damage.
Unfortunately, this variance greatly increases the likelihood that residents will make complaints.
Vibration Management Program
The third key step for effective vibration monitoring in construction is a vibration management program, which involves the use of vibration modeling.
Importance of Vibration Modeling
Modeling vibration sources is another proactive measure and can be incredibly useful for assessing the areas likely to be impacted by the construction operations that could be critical or be out of compliance if not properly analysed, predicting the potential risks of exceedances, and to plan for any necessary vibration reduction mitigations — all in advance.
During that phase, vibrations to the structure are analysed and compared to standards and regulations to ensure compliance of the construction operations.
Anticipating Risks
By taking the proactive approach, anticipating (and having a management plan) for any potential risks, ultimately avoids being caught unprepared. By identifying specific areas and the times by which they pose the greatest risk of vibration exceedances, you can plan and implement the necessary vibration mitigation measures, know where to put the vibration monitors, in advance, to minimize any site interruptions that could slow/cease site operations.
Optimizing Resources
A highly specialized and knowledgeable vibration team, well aware of the different standards and best practices, is a valuable resource to have on any construction project, as they are essentially there to provide guidance and support for any challenges that may arise.
Vibration Monitoring Plan
As part of the management program (and indicated above), vibration experts will have already identified the areas at risk for exceedances and will have determined the appropriate control methods that will be most effective for the project at hand.
The Vibration Monitoring Plan contains the particular methods and tools that will be used to achieve effective vibration monitoring. This plan includes:
- Installation of Vibration Monitors: Determining when and where to install the vibration monitors, the type used (MEMS or geophones), optimal number required, method of installation, whereas it is attached to a structure or next to it.
- Monitoring Methods: How the vibration monitors will be configured and why these choices are relevant for accurate data collection.
- Data Evaluation: Defining which parameters (standard, vibration velocity limit with respect to frequency) will be evaluated to ensure effective and proactive vibration monitoring.
- Communication & Data Management: How information will be communicated, who will receive the alerts when levels are exceeded, and how these alarms will be configured, etc.
- Vibration monitoring duration: Establishing the duration of time that will ensure continuous, relevant monitoring throughout the project.
- Generated Reports: How information will be generated and shared (frequency, reference standard), also enabling strategic adjustments if necessary.
This detailed approach makes it possible to effectively plan, implement, and ultimately manage vibrations on site, in order to minimize the risk of overruns, and maintain the required safety measures and compliance over the course of the project.
By utilizing portable and compact monitoring devices, construction teams can dedicate resources to frequently assess vibration levels and respond with timely instruction to prevent any potential delays or issues.
Vibration Monitoring Equipment
The selection and deployment of vibration monitoring equipment are guided by the Vibration Monitoring Plan, ensuring that the tools, methods, and configurations are tailored to the specific needs of the project for accurate and reliable data collection.
Vibration monitoring equipment plays a crucial role in construction projects, particularly during activities like pile driving and demolition. These operations can generate significant ground vibrations, which can impact nearby structures. Continuous vibration monitoring system generally includes a vibration monitoring station, sensors, and a cloud-based web interface that allows you to manage multiple stations effortlessly.
Using charts or graphs, stakeholders can visualize vibration trends and make decisions about on-site equipment configurations and project timelines. With advanced vibration monitoring solutions, teams can minimize risks and protect both their structures and the neighboring community.
Typically, vibration monitoring equipment consists of vibration monitors — such as geophones, MEMS sensors, and borehole installations — along with monitoring stations and a web-based monitoring platform.
Geophones — Accurately Measure Vibrations Velocity Caused by Blasts, Hydraulic Hammers, and Other Impulsive Sources
To effectively monitor these vibrations, various devices such as triaxial geophones can be employed to measure velocity of the waves generated transfered in the ground by the construction activities. This sensor helps identify the source of the vibration, providing valuable insight into potential impacts on adjacent structures. By analyzing the waveform and calculating the peak particle velocity (PPV), contractors can ensure that the vibrations remain within safe limits as outlined in industry guidelines like those from DIN 4150.
Soft dB's Smart Geophone Sensor is perfectly suited for identifying microearthquakes and assessing vibrations from activities such as blasting, hydraulic hammers, piling, and more, making it a perfect choice for construction and mining vibration monitoring.
Its outstanding signal quality allows for the detection of vibrations as subtle as one micrometer per second, without the danger of high-frequency saturation.
This triaxial geophone is ideal for monitoring vibrations in proximity to impact sources, such as a jackhammer operating near a wall.
The advanced features of the Smart Geophone Sensor ensure the safety of structures, buildings, and infrastructure near the work area, safeguarding vibration-sensitive equipment and ensuring the comfort of residents in the surrounding communities.
Vibration Monitor Based on MEMS — Measure Strong Motion Caused by Induced Seismicity
Multiple standards, including USBM and ISSE, suggest that to achieve precise vibration monitoring of strong motion, such as velocity and frequency during an earthquake or during blasting, it is advisable to ensure proper transfer of vibration through adequate coupling.
Consistent with industry standards, our SVS vibration sensor boasts an IP68 rating, ensuring it is highly durable and capable of being fully submerged in water while enduring harsh conditions. This sensor is compliant with various standards such as ISEE, DIN or AS2187.2 and allows to measure strong motion at low frequencies, where a geophone, by it's technology, is less adapted to monitoring strong motion.
As a result, the SVS is an ideal choice for permanent setups, such as seismic vibration monitoring.
To guarantee reliable communication in areas with weak cellular signals, our SVS employs a wired connection, delivering accurate, interference-free data. With up to 100 meters of cable, it provides sufficient flexibility to position the SVS optimally for monitoring your most critical locations, where wireless sensors would limit you in the location of the installation.
Borehole — Efficiently Monitor Underground Vibrations
A borehole geophone is a seismic instrument crafted to detect underground vibrations caused by activities such as construction, blasting, and more.
Robust and rated IP68, Soft dB's triaxial smart borehole provides unique functionalities: easily accessible surface electronics, affordable replacements, interference-free digital transmission over extended distances, automatic sensor diagnostics, and more.
Vibration and Noise Monitoring Station
Operations that create substantial vibration, like blasting and drilling, typically generate considerable noise as well. As a result, monitoring both vibration and noise levels is often essential.
Our Watch noise and vibration monitoring station is capable of measuring various contaminants at once, including noise, vibration, air overpressure, and beyond. There’s no need to invest in an extra station or juggle multiple platforms with various notifications from different providers! The Watch monitoring station streamlines the entire process.
Web-Based Monitoring Software: Monitor Your Vibration in Real-Time, Continously, 24/7
Whatever type of Soft dB sensor you require, our monitoring web platform brings together all gathered data, alerts, and supplementary information into one unified interface.
Our platform is designed to meet real-world needs: it is simple, easily accessible, user-friendly, and flexible, offering all the tools necessary for comprehensive data analysis and visualization.
No matter which Soft dB sensor you need, our monitoring solution combines all recorded data, alerts, and more into a single web interface. Highly effective and intuitive for visualizing and managing all your vibration and sound data in real-time, remotely, and completely centralized in one location.
Implementing the Vibration Monitoring Plan
Implementing a vibration monitoring plan is a critical step to ensure that construction activities do not cause damage to nearby buildings and structures. This step is a standard requirement in most construction proposals and provides essential data for mitigating vibration-related risks.
There's no need to stress the importance of this key step.
However, there's an important factor to take into consideration that is often overlooked: the types of seismographs offered by manufacturers.
During the vibration monitoring phase, it is often necessary to place sensors in confined locations, such as basements, tunnels, or underground parking lots. However, real-time data transmission has often shown to be a problematic issue — especially when the corresponding vibration monitors need to be buried.
Soft dB has developed an effective solution: a sensor that is capable of managing both data acquisition and transmission locally — providing greater flexibility and responsiveness for our clients.
This approach gives the same advantages as a wired sensor, while avoiding the limitations of being wireless, which has been a game changer for effective data transmission. Furthermore, it’s smart, reliable, and designed to flexibly meet the needs of any project.
Soft dB’s vibration monitoring plan offers several key advantages, including:
- Master Trigger™, Soft dB’s patented blast monitoring feature that filters out false positives, saving our clients time and money by only sending notifications for true exceedances.
- Wireless access to all collected vibration data, via Soft dB’s well renown, user-friendly, and customizable, web-based monitoring platform.
- A wide collection of various sensors, easily adaptable to the needs of any project.
Vibration Monitoring Final Report — In Option
The vibration monitoring final report is an additional measure that is completed after construction activities have come to a close. It typically includes a summarization of the mitigation measures that were put in place and provides clarification of any overruns that occurred during construction operations. Additionally, this document can also be used to quickly show whether the vibration standards had been met (or exceeded) for the duration of active construction activities. Furthermore, it can be tremendously helpful for any potential litigation challenges that may be brought into question “after-the-fact”.
Although this step is not essential, it is an excellent practice to have and highly recommended and a final step for finalizing and closing a project file.
Choose a Solution for Vibration Monitoring in Construction. Not Just an Instrument That Provides a Number.
While cost effectiveness is an important priority when it comes to managing a construction project, the benefits of investing in a proactive approach will always outweigh the costs of operating reactively. When you choose the right team of experts, that have decades of knowledge and experience in noise and vibration, that develops and manufactures cutting-edge monitoring equipment, instrumentation and software (also well renowned world-wide), they will be able to provide you with the highest level of support, equip you with the most effective solutions, and ensure superior satisfaction.
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