Abstract
In predicting the impact of vibrations propagated in a ground on newly designed construction objects, it is extremely important to reliably measure the time histories of velocity or acceleration at the site of the planned investment. As some studies show, the method of coupling accelerometers and geophones to the ground can affect not only the level of peak particle accelerations (PPA) or peak particle velocities (PPV)—commonly used in this type of evaluation—but also vibration frequency distribution of recorded signals. This makes it difficult to compare and analyze the results obtained by various research teams. Conclusions based on this type of comparison may be wrong. For this reason, it is extremely important that reliable dynamic measurements related to the propagation of ground surface vibrations should be carried out using not only appropriately selected measuring equipment (with the required sensitivity and measurement ranges—both in the time domain and frequency domain), but also the measurement bases/setups used for mounting various types of transducers, whose natural frequencies will be outside the frequency range relevant to the possible impact of vibrations on buildings and human beings inside. The paper presents the results of modal analyses carried out with the use of Ansys Engineering Simulation and 3D Design Software (based on the Finite Element Method) for three different types of measuring bases used to coupling accelerometers to the ground. Measuring bases selected for numerical analyses were in the form of a stiff steel spike of an X-shaped cross section (a measuring base No. 1) and two steel spikes of L-shaped cross-sections (a measuring bases No. 2 and No. 3). In the places of screwed accelerometers (three different types of IEPE/ICP transducers of varying sensitivity and a weight) point masses were attached to the measuring bases. As a result of the analyses, it was possible to determine the impact of individual methods of coupling of accelerometers to the ground on the reliability of recorded ground surface accelerations. Among others it was concluded that in each analyzed case the lowest natural frequencies of the measuring bases with attached accelerometers significantly exceeded 100 Hz. The widest frequency band free of resonance vibrations can be provided by the measuring base No. 3 (L50 × 50 × 5).
Highlights
An inseparable element of the civilization progress accompanying the dynamic development of industry and trade is the need to erect new industrial facilities, residential and public utility buildings as well as to expand the communication infrastructure enabling effective transport of both people and goods
Intense vibrations generated by blasting, ground vibrations caused by civil engineering works can propagate over considerable distances and negatively affect the deterioration of living comfort and use, and the technical condition of nearby located structures [1,4]
Considering the above, and based on the results of modal analyses carried out using the Ansys Engineering Simulation and 3D Design Software, it should be stated that:
Summary
An inseparable element of the civilization progress accompanying the dynamic development of industry and trade is the need to erect new industrial facilities, residential and public utility buildings as well as to expand the communication infrastructure enabling effective transport of both people and goods. Sci. 2020, 10, 3128 with a negative impact on the environment It manifests itself in the form of pollution and contamination of air, soil, and surface and groundwater; increasingly, in engineering practice we deal with environmental pollution in the form of noise and vibrations. Intense vibrations generated by blasting (in mines, quarries, and construction sites [1,2]), ground vibrations caused by civil engineering works (passing heavy equipment [3,4], soil compaction [5,6,7,8,9], sheet pile driving and pulling out [10,11], pile driving [1,4,5,12], or traffic-induced vibrations [13,14,15,16]) can propagate over considerable distances and negatively affect the deterioration of living comfort and use, and the technical condition of nearby located structures [1,4]
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