Seismic Wave Shield Columns for Low-Frequency Attenuation
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Solution Overview
Problem
Existing seismic defense structures are ineffective in blocking low-frequency seismic waves that cause significant damage to buildings, as they often match the resonant frequencies of structures and travel long distances, especially in urban areas with machinery and railway vibrations.
Innovation Solution
A seismic wave shield comprising columns embedded in regolith and in contact with bedrock, made of materials with a significant contrast to the regolith, creating a wide stop band that reflects seismic waves by producing a zero-frequency band-gap, effectively blocking frequencies from 0Hz to 10Hz, which are the most damaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If empty boreholes are used in a periodic pattern to block seismic waves, then the structure is simple to implement, but the stop band frequency range is limited and does not cover low frequencies effectively
Solution Approach 1:
The patent changes the physical parameters of the defense structure by filling boreholes with materials of contrasting density and elastic properties (such as concrete, steel, or rubber) instead of leaving them empty. This material parameter change transforms the structure from blocking only high-frequency waves to effectively blocking low-frequency seismic waves (1-10 Hz) while maintaining implementation simplicity.
Solution Approach 2:
The patent employs composite material structures where columns of contrasting materials (different densities and elastic moduli) are embedded in the ground. These composite structures create multiple scattering centers that generate broader stop bands covering low frequencies, while the periodic arrangement maintains ease of construction similar to the empty borehole approach.
2Adaptability or versatility
If large diameter boreholes are used to block low-frequency seismic waves, then the frequency coverage improves, but the complexity and difficulty of installation increases significantly
Solution Approach 1:
The patent segments the seismic wave blocking function into multiple smaller columns distributed periodically in the ground. Instead of requiring one or two large boreholes, numerous smaller columns (each easily installable) collectively create the same or better low-frequency blocking effect through cumulative scattering and interference, dramatically reducing installation complexity.
Solution Approach 2:
The patent changes the size parameter of the boreholes from large diameters to small diameters, compensating for the reduced individual blocking capability by increasing the number of columns and optimizing their periodic spacing. This parameter transformation makes installation practical while maintaining effective low-frequency seismic wave blocking.
3Object-affected harmful factors
If meta-boxes with side-holes are used to attenuate seismic waves, then wave attenuation is achieved, but the structure requires huge dimensions and is not practical for urban areas
Solution Approach 1:
The patent replaces the huge three-dimensional meta-box structures with thin vertical columns that act as scattering centers. These columnar structures achieve similar wave attenuation functionality with minimal volume, allowing deployment in urban environments where space is constrained, while effectively attenuating low-frequency seismic waves through material contrast.
Solution Approach 2:
The patent changes the geometric parameters from large-scale meta-boxes to slender columns with high aspect ratios. This parameter transformation reduces the volume requirement dramatically while the periodic arrangement and material contrast properties ensure effective seismic wave attenuation is maintained.
4Adaptability or versatility
If periodic arrays of columns with material contrast are used, then a wide stop band covering low frequencies is achieved, but the question arises whether practical installation is feasible
Solution Approach 1:
The patent divides the seismic defense function into numerous small, identical column units that can be installed independently in a periodic pattern. Each column is small enough for standard drilling and installation equipment, making the entire array practical to install despite the large number of units required for broad frequency coverage.
Solution Approach 2:
The patent optimizes the size and spacing parameters of the columns to achieve practical installation feasibility. By selecting column diameters suitable for standard borehole drilling equipment and spacing them at practical intervals, the design achieves wide stop band coverage while remaining implementable with conventional construction methods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The seismic wave shield significantly reduces the transmission of damaging low-frequency seismic waves, providing effective protection to buildings by creating a wide stop band that covers the frequencies causing the most damage, while being practical for installation in urban areas without requiring large holes.
Implementation Method 1
The columns are formed of a material with a material contrast with the regolith. The larger bandwidth of the stop band of the present invention over the prior art is due to the contact between columns and bedrock and a material parameter (for example, the density and/or Young's Modulus and/or Bulk modulus and/or shear modulus) mismatch between the regolith (often soft soil) and the material in the column.
Implementation Method 2
The effect is caused by wave physics, so the composition, arrangement and shape of the columns can be chosen according to wave physics to produce the desired stop band.
Implementation Method 3
The test showed reduced transmission through the ground of seismic waves of around 50Hz due to destructive interference of seismic waves in the transmission direction caused by the periodicity of the grid
Data Source
Figure 1
Figure 2
Figure 3a~3c
AI summary
A seismic wave shield for protecting an area from seismic vibrations and a method of shielding an area from seismic waves by installing a seismic wave shield. The seismic wave shield comprises a set of columns (1) embedded in regolith (3) and in contact with bedrock (4). There is a material contrast between a material forming the columns (1) and the regolith (3).