Man-made Vibrations Research Articles

Experimental Study on Reutilization of Waste Rubber Chips with Sheetpiles as a Coupled-Wave Barrier to Reduce Ground-Borne Vibrations

Abstract Purpose Environmental and man-made vibrations due to various sources have become an environmental issue in recent years. Wave barriers such as open and in-filled trenches have been commonly used in the mitigation of these vibrations. Even though the open trench has exhibited better performance than the others, it may not be applicable or feasible in many cases. Therefore, soft and stiff barriers have been used for the same purpose. The present study aims to reveal the vibration isolation performance of not only single barriers such as rubber chips in-filled trenches and sheetpiles but also a novel barrier, rubber chips-sheetpile coupled barriers. Methods Rubber chips and sheetpiles were employed as soft and stiff wave barriers, respectively. The screening effectiveness of rubber chips, sheetpiles and their coupled form was examined through comprehensive field tests. Vibrations having frequencies in the range of 10–80 Hz were generated by a state-of-the-art mobile seismic shaker and measured by highly sensitive acceleration and velocity pickups in the absence and presence of these wave barriers. The effectiveness of the wave barriers was quantitatively determined. Results and conclusion While the sheetpile was more effective than rubber chips at low frequencies, the case was vice versa at higher frequencies. However, the coupled wave barrier outperformed other barriers in each case. If one barrier could not provide the required amount of isolation or is only effective within a limited range of frequency, using a coupled barrier with the installation of the other may significantly provide better vibration isolation.

Variation-Difference Method of Calculation of Layered Rubber-Metal Vibration Isolators Used for Protection of Reinforced Concrete Buildings from Anthropogenic Vibration

In the modern construction complex of the city of Moscow for the protection of buildings and structures from man-made vibration arising from the movement of trains of rail transportation (subway trains, railroad lines and trams). To protect buildings and structures from anthropogenic vibration arising from the movement of rail transport trains (subway trains, railroad lines and streetcars), Moscow uses layered rubber-metal vibration isolators [1]. Most often, to determine their static and dynamic characteristics, the finite element method (FEM) is used, which makes it possible to determine all components of the stress-strain state and frequencies of free oscillations in the loaded state practically for any structural forms of isolators. However, for the most popular software packages that implement FEM, the problem of optimizing the structural shape of the vibration isolator still requires significant time expenditures for multiple changes of the finite element mesh, repeated setting of boundary conditions and implementation of a series of calculations. Only some of the software packages implementing the FEM solve optimization problems of the shape of the product being calculated, most often it is related to foreign software products with universal functionality. Variation-difference method (VDM) is the closest to the finite element method (FEM) in terms of its computational capabilities. It is possible to create program modules that repeatedly and automatically solve three-dimensional problems of elasticity theory taking into account the changed geometry of the vibration isolator: the dimensions of the product, the location of perforations within the rubber layers, as well as the thickness of the rubber layer and other parameters important for obtaining an effective technical solution for vibration isolation of buildings. Further, the article describes the method of implementation of the variational-difference method (VDM) as applied to the solution of the problem of determining the components of the stress-strain state inside a three-dimensional layered vibration isolator with perforations of different sizes having different locations relative to the contour of the vibration isolator, i.e., the solution of the problem of optimizing the three-dimensional shape of the vibration isolator is given.

Prediction of Traffic Vibration Environment of Ancient Wooden Structures Based on the Response Transfer Ratio Function.

Traffic-induced vibration is increasingly affecting people's lives, which necessitates scrutiny of the environmental vibrations caused by traffic. This paper proposed a vibration prediction method suitable for the ancient wooden structures subjected to traffic-induced vibrations based on the multi-point response transfer ratio function. The accuracy of the proposed approach was also checked by comparing the predicted results with the measured results in the context of both the time domain and frequency domain. Subsequently, the environmental vibrations due to heavy-duty trucks passing at various speeds were measured, and the measurements were utilized as the input vibration excitation to assess the structural vibration of the Feiyun Pavilion. The structural safety was evaluated according to the "Technical specifications for protecting historic buildings against man-made vibration". In order to meet the structural safety requirements of the Feiyun Pavilion, it is strongly recommended to limit the type and speed of vehicles in the nearby area.

Studying the interaction of a reservoir with an ideal compressible fluid with an elastic half-space

We solve in a flat formulation the problem of harmonic oscillations for a basin with an ideal compressible fluid on an elastic half-space exposed to a localized surface vibration load. The problem reduces to an integral equation (IE) of the first kind for the amplitude of the contact hydrodynamic pressure with a kernel that depends on the difference and the sum of arguments. The IE was solved by the factorization method. A semi-analytical method is presented for determining the main parameters of the contact interaction in hydroelastic systems «liquid-soil» taking into account the effect of natural and man-made vibration loads on them. This makes it possible to identify the conditions for the occurrence of dynamic modes that are dangerous for the construction integrity and to estimate their frequencies range depending on defining characteristics of the system.

НЕСТАЦИОНАРНОЕ КОНТАКТНОЕ ВЗАИМОДЕЙСТВИЕ АБСОЛЮТНО ТВЕРДОГО УДАРНИКА И УПРУГОГО ПОЛУПРОСТРАНСТВА С ЗАГЛУБЛЕННОЙ ПОЛОСТЬЮ

A closed mathematical formulation of plane non-stationary contact problems for rigid dies and an elastic half-space with deepened cavities is constructed. Using the dynamic theorem of reciprocity of works, a system of resolving equations is obtained. It includes the basic boundary integral equation arising from the principle of reciprocity and boundary conditions, as well as the equations of translational and rotational motion of the die. The fundamental and singular solutions for the elastic plane are the cores of the main resolving equation. They determine displacements and stresses in the elastic plane from the applied single instantaneous concentrated force. An original solution algorithm based on the method of boundary integrals with an additional iterative procedure that allows one to take into account the partial separation of the boundary surfaces of the die and the half-space in the contact area has been developed and implemented on a computer. In this case, at each moment of time in the half-space, there is a region that is in a perturbed state and outside of which there are no perturbations. The integral operators of the resolving system of equations are replaced by discrete analogs in the spatial variable and in time. A parametric study of the process of unsteady contact of an absolutely rigid rectangular die with a half-space having a recessed cavity is carried out. Analysis of the calculation results revealed the manifestation of a significant effect of the cavity on the process of non-stationary contact interaction. The influence of the cavity begins to show itself from the moment the reflected waves arrive from its boundary. In this case, the nature of the unsteady stress-strain state and displacements changes significantly. The developed calculation algorithm can be used in engineering practice by design and research organizations in the process of designing and calculating buildings and structures under the influence of natural and man-made vibrations propagating in the soil.

The surface wave attenuation as the effect of vibratory compaction of building embankments

There are two different sources of dynamic effects observed on buildings and structures - natural phenomena and human activities. Both may be related to the mining production or civil engineering construction. Ground vibrations induced by human activities characterize much lower intensity compared to the natural phenomena like earthquakes. However, due to the high urban development and sustainable development ideas, preventing the destructive effect of man-made vibrations belongs to the most important problems considering the structure and soil dynamics. Construction activities, road and railway traffic, and operation of machines, including crushing of spoil material (debris) from demolition works are the main categories in the classification of human activities which can generate ground vibrations. This paper takes a special interest in the first of the factors mentioned above. It is evident that the main construction or demolition activities causing dynamic problems in close proximity of structures are caused by pile or sheet pile driving and dynamic soil compaction by means of vibratory rollers or impulse compactors; as well as by demolition of structures, rock excavation and soil deep compaction by explosives. The vibration monitoring process needed to prevent structures from damage is described by various standards. They give particular criteria depending on various technologies and construction materials. The reduction of man-made ground vibrations is now the crucial scope of interest due to the need for sustainable technologies implementation. The negative environmental impact may be reduced at the source. Some new specialized methods are also proposed for minimizing the vibration transmission with the use of an active generator. The aim of the presented paper is to describe the modelling of dynamic vibratory soil compaction, using finite element method. The presented solution is addressed to short time vibration, generated by geotechnical works. This conclusion can be helpful by panning geotechnical works in the neighbourhood of vibration sensitive buildings/structures.

Deformable unsaturated laterite soil under vibration impact with dissimilar moisture content

Vibrations from vehicle traffic, machinery and operations from construction activities such as blasting are examples of some natural and man-made vibration phenomenon’s that can cause dynamic stress when imposed onto soils. In order to ensure sustainability of the geo-environment, the impacts caused by these vibrations as well as the changes in moisture content needs to be addressed. To achieve this, the behaviour of vibrated deformable double-porosity under dissimilar moisture content in non-repeated vibration was assessed and characterized through laboratory experiments. Investigation of deformable unsaturated laterite soil by aggregating laterite soil using 29%, 30%, 32% and 34% moisture content was carried out and presented in this paper. An acrylic soil column, accelerometer and vibrating table were used to conduct the experiments. The acrylic columns were filled with each aggregated soil and the soil was then compressed to a height of 10 cm, which had been pre-determined beforehand. Accelerometers were installed to a vibrating table where each soil column was tested to measure the time histories of high-frequency acceleration on the surfaces of both the laterite soil and vibrating table. Acceleration was observed at two points, namely; (1) the surface of the soil sample and (2) the surface of the vibrating table. The amplitude of the vibrating table was increased in order to test for repeated vibration. Maximum amplitudes were recorded by collecting the acceleration time histories and the amplitude of displacement was increased in order to carry out the tests. The outcome of the tests demonstrated that there was an increase of the acceleration response in non-repeated vibration when moisture contents were also increased. For the vibrated samples that were used, it was found that there was a rearrangement of the soils structure and as expected, the porosity characteristics that were identified had influenced the liquid penetrations’ speed.

Vibration impact towards deformable laterite soil with different moisture content

In engineering practice, natural and man-made vibration phenomenon can cause dynamic stress to be imposed on soils such as blasting, construction operations and machinery, and vehicle traffic vibrations. This issue need to be addressed to ensure the geo-environment is sustainably secure. Laboratory experiments were conducted to characterize the behaviour of vibrated deformable double-porosity under different moisture content in repeated vibration. This paper presents the investigation of vibrated double-porosity soil by aggregating laterite soil with 29%, 32% and 34% moisture content. The experiments were conducted by using acrylic soil column, accelerometer and vibrating table. Aggregated laterite soil is poured in acrylic soil column then compress until 10 cm height. High-frequency accelerometers were installed to observe acceleration at 2 points; (1) surface of soil sample, and (2) surface of vibrating table. The experiments for repeated vibration were conducted by increasing the amplitude of the vibrating table. The acceleration time histories at accelerometers were collected to observe maximum amplitude. The results showed that the acceleration response in non repeated vibration was increased with increasing of moisture contents. It was found that with vibrated samples, the soil structure was rearrange and porosity characteristics identified as expected influence the speed of liquid penetration.

Impact of Vibration on Double-Porosity Unsaturated Laterite Soil with Different Water Contents

Engineering practices, natural and man-made vibrations phenomena such as blasting, construction machinery and operations, and vehicle traffic vibrations can cause stresses to soils. In addition, changes in moisture content may affect the speed of liquid penetrating the soils. Therefore, the impacts due to vibrations and changes in moisture contents need to be addressed to ensure geo-environment sustainability. This can be achieved by conducting laboratory experiments to determine the behaviour of deformable double-porosity soil samples with different water contents subjected to non-repeated vibrations. In this study, aggregated laterite soil samples were prepared with 30% and 34% moisture contents. Each aggregated soil was poured into an acrylic column then the soil was compressed to a pre-determined height of 10 cm. Testing was performed on each soil column using a vibrating table where accelerometers were installed to measure high-frequency acceleration time histories on the surfaces of the vibrating table and laterite soil. The tests were conducted by increasing the amplitude of displacement and the acceleration time histories were collected to record maximum amplitudes. The results showed that the soil surface acceleration in non-repeated vibration was increased with increasing moisture contents. It was also discovered that the speed of liquid penetration was influenced by vibration due to rearrangement of soil particles and changes in soil structure and porosity characteristics.

Dynamic Analysis of an Office Building due to Vibration from Road Construction Activities

Construction activities are widely known as one of the predominant sources of man-made vibrations that able to create nuisance towards any adjacent building, and this includes the road construction operations. Few studies conclude the construction-induced vibration may be harmful directly and indirectly towards the neighbouring building. This lead to the awareness of study the building vibration response of concrete masonry load bearing system and its vibrational performance towards the road construction activities. This study will simulate multi-storey office building of Sekolah Menengah Kebangsaan (SMK) Bandar Enstek at Negeri Sembilan by using finite element vibration analyses. The excitation of transient loads from ground borne vibrations which triggered by the road construction activities are modelled into the building. The vibration response was recorded during in-situ ambient vibration test by using Laser Doppler Vibrometer (LDV), which specifically performed on four different locations. The finite element simulation process was developed in the commercial FEA software ABAQUS. Then, the experimental data was processed and evaluated in MATLAB ModalV to assess the vibration criteria of the floor in building. As a result, the vibration level of floor in building is fall under VC-E curve which was under the maximum permissible level for office building (VC-ISO). The vibration level on floor is acceptable within the limit that have been referred.

Deep Shear Wave Velocity of Southern Bangkok and Vicinity

Bangkok is located on the soft marine clay in the Lower Chao Phraya Basin which can amplify seismic wave and can affect the shaking of buildings during an earthquake. Deep shear wave velocity of the sediment in the basin are useful for study the effect of the soft sediment on the seismic wave and can be used for earthquake engineering design and ground shaking estimation, especially for a deep basin. This study aims to measure deep shear wave velocity and create 2D shear wave velocity profile down to a bedrock in the southern Bangkok by the Microtremor measurements with 2 seismographs using Spatial Autocorrelation (2-SPAC) technique. The data was collected during a day time on linear array geometry with offsets varying between 5-2,000 m. Low frequency of natural tremor (0.2-0.6 Hz) was detected at many sites, however, very deep shear wave data at many sites are ambiguous due to man-made vibration noises in the city. The results show that shear wave velocity of the sediment in the southern Bangkok is between 100-2,000 ms-1 and indicate that the bedrock depth is about 600-800 m, except at Bang Krachao where bedrock depth is unclear.

PROPAGATION OF HARMONICAL VIBRATIONS IN PEAT

In order to check the reliability of man-made vibration prediction methods, vibration tests were performed on one of polders in the North-West of the Netherlands. The polder was chosen because it has a rather homogenous, thick and soft peat top layer. Here sufficient harmonical vibrations could be generated by a rather small shaker. The shaker was designed and manufactured in order to produce harmonical vibrations at the soil surface. It consists of two counter rotating electric vibrators (with rotating eccentric masses) in order to produce a vertically oscillating force. For the recordings of the vibrations, six 2D or 3D geophones were placed on the soil surface and one 2D geophone was placed on top of the shaker. The measured vibration amplitudes of the vertically oscillating shaker were compared with 1. Two different analytical methods used for the design of vibrating machine foundations, 2. The Confined Elasticity approach and 3. The Finite Element Method, for which Plaxis 2D software was used. Also the measured vibration amplitudes at the soil surface were compared with Barkan- Bornitz's solution and Finite Element Modeling.

Dynamic Response Analysis of Xi'an Bell Tower Timber Structure under the Metro-Vibration Loading of Line 2 and 6

The effects of metro line 2 and line 6 on Xi'an Bell Tower was studied by numerical analysis in this paper. At first, according to the theory of Euler-Bernoulli beam in Winkler foundation, the analysis model of train-track-foundation system was established, and then, time-history curve of metro-induced loading acts on tunnel structure is obtained by using Matlab produce platform. Secondly, two-dimensional finite element model of the structure-soil-tunnel interaction model was established using ANSYS. Finally, the impact of metro line 2 and 6 and ground transportation on Xi’an Bell Tower was evaluated according to the Technical specification for protection of historic buildings against man-made vibration. The construction of Metro Line 2 and Line 6 will affect the safety of Xi'an Bell Tower.

Dynamic Response Analysis of Xi'an Bell Tower Timber Structure under the Metro-Vibration Load of Line 6

Taking Xian Bell Tower and metro line 6 as research background, at first, according to the theory of Euler-Bernoulli beam in Winkler foundation, the analysis model of train-track-foundation system was established, and then, time-history curve of metro-induced loading acts on tunnel structure is obtained by using Matlab software. Two-dimensional finite element model of the structure-soil-tunnel interaction model was established using software Ansys,. Taken loading time delay into consideration for the first time, dynamic response law of the bell tower under the metro-vibration loading is obtained. Finally, the impact of metro line 6 on Xian Bell Tower was evaluated according to the Technical specification for protection of historic buildings against man-made vibration. Xi'an Bell Tower timber structure is safe when two trains running of the line 6.

Dynamic Response Analysis under the Metro-Vibration Loading of Xi'an Bell Tower Timber Structure

Taking Xi’an Bell Tower and metro line 2 as research background, at first, according to the theory of Euler-Bernoulli beam in Winkler foundation, the analysis model of train-track-foundation system was established, and then, time-history curve of metro-induced loading acts on tunnel structure is obtained by using Matlab produce platform. Secondly, two-dimensional finite element model of the structure-soil-tunnel interaction model was established using ANSYS. Taken loading time delay into consideration for the first time, dynamic response law of the bell tower under the metro-vibration loading is obtained. Finally, the impact of metro line 2 on Xi’an Bell Tower was evaluated according to the Technical specification for protection of historic buildings against man-made vibration.

Enhanced detection capability of non-volcanic tremor using a 3-level vertical seismic array network, VA-net, in southwest Japan

[1] This study evaluates a method that enhances detection of non-volcanic low frequency tremor (NVT) using VA-net, a 3-level vertical seismic array network that was recently constructed in southwest Japan. The method employs semblance analysis for continuous vertical array records and calculates semblance coefficients as a function of time and apparent vertical velocity. The sign of the best apparent velocity provides information about propagation direction, either upward or downward, allowing easy discrimination between seismic signals of natural origin and unwanted noise such as man-made vibrations. We applied the method to a NVT episode that occurred beneath the Kii Peninsula during November 2008, to demonstrate that NVT signals can be detected using only the 3-level array. Furthermore, we demonstrate that the method enables us to detect minor NVT activity which is not detected by a conventional envelope cross-correlation method, resulting in a dramatic improvement in detection capability.

A Non-Resonance Method for Measuring Dynamic Soil Properties

Abstract A non-resonance (NR) test method is introduced to determine dynamic soil properties at low strain amplitudes over a broad frequency range using a conventional resonant column/torsional shear (RC/TS) apparatus. The theoretical background of the NR method is presented and it is shown that the shear modulus and material damping ratio can be obtained from frequency response measurements between the applied torque and resulting rotational displacement of the specimen. By properly accounting for inertia effects, the NR method allows measurements at frequencies (e.g., 2–30 Hz) that fill the gap between conventional RC and TS tests. Experimental results are presented for aluminum alloy, polymethyl methacrylate (PMMA), and soil specimens over the frequency range of 0.01–30 Hz. Values for aluminum alloy and PMMA, used as calibration materials, obtained with the NR method agree well with reference values from the literature and help validate the approach. Tests on two soil specimens indicate that the NR method permits continuous measurements of shear modulus and material damping ratio of soils over a broad frequency range, which has the potential to yield improved understanding of viscoelastic soil behavior and provide dynamic soil properties over a range of frequencies appropriate for a variety of natural and man-made vibration sources.

Vibrations, chocs et tremblements de terre induits par l’activité humaine

Different kinds of man-made vibrations, tremors and earthquakes, the magnitudes of which may reach 6.4, are considered as compared with those natural ones. It is recommended to elaborate real economical calculations both for anti-seismic as well as normal constructions of the same high and big investment object, the exploitation of which have to persist longer period of time, with reference to location of the object and to tectonical seams of the great orogens as well as of smaller tectonic blocks, which are interconnected in the Earth’s crust.

Vibration problems in geotechnical engineering

This volume constitutes the Proceedings of a two-session Symposium whose main objective is to address geotechnical issues related to vibration problems other than those associated with earthquakes. The first session, entitled Analysis and Measurement of Machine Foundation Vibrations, contains eight papers covering analytical, experimental and design aspects of machine foundations. Procedures to predict amplitudes of machine-excited vibrations of shallow, embedded and piled foundations are described. Rigorous and simplified methods are presented, while small-scale experiments show the capabilities and limitations of such methods of analysis. Two different designs of compressor foundations are reviewed and the results of field tests aimed at evaluating their performance are presented. A numerical formulation for assessing the effectiveness of active and passive vibration isolation by means of trenches is outlined. The second session, entitled Detrimental Ground Movement from Man-Made Vibrations, contains seven papers which provide a variety of useful examples of vibration effects. Settlements caused by pile driving vibrations are examined. Observations on ground vibrations from vehicles on projects where vibrations were a problem to people or equipment are presented. Ground vibrations from various sources including dynamic compaction, vibraflotation, pile driving, machine vibrations and vehicle vibrations are also covered. Ground vibrations from dynamic (impact) compaction operations and building response to construction blast vibrations are reviewed. A study of potential detrimental effects on slope stability of vibrations from blasting is presented.