Because pipe jacking and tunneling work has a short construction period of several months or, in some cases, just a few weeks, the current reality is that noise impact assessments on the surrounding area and soundproofing measures tend to be omitted.
However, in slurry-type and earth pressure-type pipe jacking methods, the impact of mechanical noise generated from plants and generators remains the same regardless of the length of the construction period.
This article introduces a specific case study in which we did not compromise on noise countermeasures just because the period was short, and we designed and constructed a soundproof enclosure optimized for the site, starting from preliminary noise prediction studies.

　　

Challenges of Soundproofing Measures in Pipe Jacking Work: Risks Brought by Short Construction Periods

The biggest factor making soundproofing measures difficult in shield tunneling work isthe short construction period of "a few months, or in some cases a few weeks"The following is located in the

Generally, large-scale temporary structures require a certain amount of time and considerable cost for construction and dismantling. As a result, the burden of temporary work becomes disproportionately large relative to the short excavation period, leading to many cases where noise impact assessments (simulations) for the surrounding area are omitted during the planning stage, relying instead on simple soundproofing sheet enclosures.

However, no matter how short the construction period may be, the impact of noise generated from sound sources such as muddy water plants, earth pressure equipment, and large generators on local residents remains the same. The excuse of "the period is short" cannot be a justification for tolerating environmental impacts caused by noise leakage.

If construction starts with only basic mitigation measures, there is a constant risk that environmental standards (45dB to 50dB or less) will be significantly exceeded, leading to the suspension of nighttime work and the resulting major delays in the construction schedule. Even on sites with short schedules, it is essential to accurately predict the impact on the surrounding environment prior to construction and plan optimal soundproofing measures that balance the construction schedule with sound insulation performance.

　　

Background of consideration for countermeasures (Flow from consultation with Yakumo to the proposal of countermeasures)

During the construction planning stage of this project, we were consulted by Yakumo regarding a noise study.

We are considering the process from inquiry to the proposal of countermeasures in the following flow.

　　

• 1. Conduct noise simulation
  Based on the construction plan drawings and equipment data, we calculate the sound pressure levels of the mud pressure slurry pipe jacking plant, generators, etc. We will conduct a simulation of the noise impact at the site boundary if no countermeasures are taken.
  　　

• 2. Determining the soundproof house grade
  Based on the evaluation results from the simulation, we will select the optimal grade of the soundproof enclosure (sound insulation and absorption performance) that meets the target noise reduction (dB).
  　　

• 3. Study and proposal of shape design tailored to the yard
  Based on the determined grade, we verify the equipment layout and crane turning radius within the limited yard. At the drawing stage, we design and propose a house shape that fits into the space without compromising workability.
  　　

Noise Simulation Results | Comparison of Countermeasure Target Values and Acoustic Calculation Results

The results of the noise level prediction calculations (simulations) performed at each sound receiving point (surrounding impact assessment points) during the preliminary construction planning stage are as follows:

　　

■ Predicted Calculation Results List (Noise Level Unit: dB)

　　

Noise mitigation measures	P-1 Height 4.5m quasi-industrial zone	P-2 Height 4.5m quasi-industrial zone	P-3 28.5m high quasi-industrial zone	P-4 Height 4.5m Category 1 Residential District
Countermeasure target value	55	55	55	45
If there are no noise reduction measures	77	80	64	68
soundproof house BSK-A type	53	57	44	45
soundproof house BSK-B type	49	53	40	40
soundproof house BSK-C type	42	46	33	33

　　

*Blue text satisfies the target value or less
*The sound receiving point height for P-3 (28.5 m) is set in consideration of the impact on nearby high-rise structures (such as condominiums).
Since the areas around P-1 to P-3 belong to a quasi-industrial zone and P-4 belongs to a Category 1 residential zone, environmental standard values (target values) are set according to the respective land uses.

　　

Noise prediction contour map

　　

Determination of noise reduction measures and specifications of the soundproof house

From the above acoustic calculation results, it was found that without countermeasures, all sound receiving points will significantly exceed the target values. In addition, while the "BSK-C type," which has the highest sound insulation performance, would well fall below the target values, constructing temporary structures with excessively high specifications for a short construction period of just a few weeks to months imposes a heavy burden from the perspective of optimizing the schedule and costs.

Synthesizing these simulation results, as a temporary soundproof house for the slurry pipe-jacking work of this project that satisfies the required sound insulation performance while minimizing the impact on the construction period,「Unit-type soundproof house Harmony Panel (BSK-B type)」selected and installed.

　

Reasons for selecting the "Harmony Panel (BSK-B Type)"

Constructing large-scale steel structures with soundproofing panels (for roofs and walls) for short-term pipe jacking projects poses a significant burden in terms of schedule and cost.

This productA structure combining column steel frames and soundproofing panelsfeatures and does not require reinforcing braces. This minimizes the number of components and the on-site assembly process, making it the optimal type chosen because it does not pressure the short tunneling schedule.

　　

Key specifications andforte

interpoint (interword separation)High workability and shortened construction periodRapid on-site construction is enabled by a unitized structural system in which column-steel-integrated panels are hoisted by crane and joined sequentially.
　

interpoint (interword separation)Sound insulation and sound absorption performance suitable for noise source countermeasures in slurry pipe jackingThe panels making up the walls and ceiling of the house contain sound-absorbing material that not only provides sound insulation against the outside, but also suppresses internal reverberation, effectively blocking noise generated from plant equipment and various pumps.
　

interpoint (interword separation)Flexibility in shape layoutBecause panels can be flexibly combined in both horizontal and vertical directions, flexible shape designs tailored to site constraints and equipment layouts at each location are possible.

　　

　　

　　

Construction Result | Achieved target noise levels at all sound receiving points

As a result of introducing this grade of soundproof house (BSK-B type), including P-4 (target 45 dB) which belongs to a Category 1 Residential District (an area subject to particularly strict standards),Cleared the target noise level at all sound receiving points in the quasi-industrial district and Class 1 residential district.I was able to do it.

This successfully combines "rapid workability suited for short construction periods" and "reliable consideration for the surrounding environment," allowing the project to be completed safely without affecting the excavation schedule.

　　

Summary | Noise prediction in advance is the key for microtunneling construction with short working periods

In pipe jacking and tunneling work, rather than simplifying noise reduction measures due to a short construction period, selecting a "rapid-installation type" soundproof enclosure suited to the site's work schedule and yard conditions is an extremely effective approach for ensuring reliable schedule management.

At Yakumo, just like in this case, we offer a comprehensive, one-stop service—from selecting the optimal house grade based on preliminary noise impact assessments (simulations), designing shapes to fit limited workspace, flexible construction tailored to actual dimensions, to speedy on-site installation.

If you are a construction manager or project owner facing challenges such as "our company lacks the know-how to evaluate noise" or "we don't know how to arrange soundproof enclosures in a limited yard," please feel free to contact us.