Papers by Keyword: Ground Vibration

Abstract: The effect of cut height on collapse area is simulated and analyzed by dynamic finite element software. Meanwhile, the simulated collapse processes of the cooling tower with different cut height were completed in a parallel study, the results of which are briefly introduced in this paper. The results show that: as the cut height increases, ground vibration on surrounding structures and collapse area of cooling tower decreases. At last, numerical simulation results were used in blasting project, which reduced hazard of collapse vibration and verify the scientific of this method.

Abstract: Dynamic compaction is one of the densification techniques of ground improvement and extensive theoretical, experimental and in-situ tests have been used to clarify its mechanism. In this paper, a literature review about the dynamic compaction is carried out and the emphasis is put on the reinforcement mechanism, effective reinforcement depth and influence range of vibration to give a reference for the ongoing researches of dynamic compaction method.

Abstract: The designs of the buildings are in addition to the static load exposed to ground vibrations spreading from the surrounding geological environment. Ground vibrations, which are produced by anthropogenic phenomena, are not usually the crucial load for the stability of the building. But this load have an adversely affect the walls of buildings or sensitive equipment in these buildings. This article will be deal with model study of underground barriers utilized as a protection against the spread of ground vibrations in geological environment. These underground barriers maybe used in the vicinity of roads or railway lines or in urban areas around the halls with heavy industrial activity. Material of underground barriers will be designed from material with different parameters, so that it could be assessed the best variant in terms of absorption of seismic waves. The different variations of the thickness of underground barriers and different distances from the source of vibration will be designed in the analysis. The analysis will be performed in mathematical models that will be created in the software’s based on the finite element method.

Abstract: Nanotechnology offers enormous potential for discovering new fundamental science, for creating new materials with unique and important properties, and for developing new technology. Nanotechnology deals with particles and system with dimensions of approximately 1 to 100 nanometers. Some aspects of nanomanufacturing technology facilities like nanofabrication, nanometrology requires extremely stable environment with very stringent limits of ground vibration. The ground vibrations induced due to road and rail traffic can affect the nanotechnology research activities, due to disturbances caused by the road and rail traffic induced ground vibrations on the nanotechnology processes and the measurements. The paper presents the study of road traffic and metro train induced ground vibration for establishment of nanomanufacturing technology facilities at CMTI. The road traffic and the metro train induced ground vibration were monitored inside the CMTI campus at surface level to identify the magnitude of ground vibration. The road traffic and the metro train induced ground vibrations are compared in comparison with the CMTI Nanotechnology Lab specifications. The metro train induced ground vibration levels are more in comparison to the road traffic induced ground vibration. The metro train induced ground vibration level exceeds the CMTI Nanotechnology Laboratory ground vibration specifications.

Abstract: With the development of thetimes, the floor space has been unable to meet human requirements, bututilization of urban underground space has become a kind of choice to solvevarious problems. In recent years, many international organizations andresearch institutions have begun to develop urban underground space, and otherissues have been discussed in a number of meetings. As a new type of transportation, subwaycan effectively solve traffic congestions. This paper applies a kind of computer-aided Engineering,like ANSYS, to establish three-dimensional finite element model offour-hole parallel tunnel, Loadingthe subway train, andthen calculating, finally analyzing rules of vibrationof the surrounding ground of four-hole parallel tunnel when the subway is working.

Abstract: This study explores the characteristics of ground vibration induced by Taiwan high-speed trains on embankments. A series of field measurement data is used for evaluating near-field vibration, far-field vibration, and vibration influence distance. Various influence factors, including train speed, ground shear wave velocity, frequency dependence, and volume of the structure, are applied for evaluation. Based on the analyses, the near-field ground vibration mainly depends on the train speed, ground shear wave velocity, and frequency dependence. The far-field vibration propagation is affected by ground shear wave velocity and frequency dependence. In general, the high frequency range has the highest attenuation coefficient and the low frequency range has the lowest. The influence distance in hard ground is the farthest, whereas the soft ground is the shortest. Finally, a specific ground vibration assessment is established using these characteristics.

Abstract: Ground vibration caused by pile driving is a kind of mechanical vibration, and the research of its characteristics is the premise of the effect evaluation on surrounding environment. With the engineering example by the analysis of vibration monitoring, the results show that the vibration frequency is low, and there is a power function relationship between the vibration velocity and the distance from monitoring point to the pile. It can be used for impact evaluation of vibration according to the fitting equation.

Abstract: The frequency component of ground vibration induced by train is complex. The propagating attenuation characteristics of ground vibration are dependent on frequency. A new prediction method based on Bornitz model for predicting the train-induced ground vibration is presented in this paper. This approach divides the frequency component into many small frequency bands according to one-third-octave. Then it predicts the vibration acceleration level VAL of each frequency bands based on Bornitz model respectively. Finally, the predicted value of Z-vibration level VL_Z is computed by the predicted value of VAL and the corresponding frequency-weighting value C. The traininduced ground vibration was measured and predicted in Chengdu-Dujiangyan railway. The results of comparing the predicted value of VL_Z with the measured value show that the prediction value of VL_Z is 3.8dB less than the measured value in the prediction point of 25m away from the railway, where the vibration strength occur rebound. In other five prediction points the ground vibration predicted value are 1.3~3.1dB more than measured value. This study shows that using the prediction method presented in this paper for predicting train-induced ground vibration has good accuracy on the whole.

Abstract: The exciting source of ground vibration from urban rail generally consists two parts, a quasi-static load moving through the railway, and a dynamic interaction between wheel and rail. The latter is caused mainly from the wheel-rail unevenness, and usually described by a power spectral density function, PSD in brief. From the three dimensional point of view, this kind of exciting source can hardly be measured directly. A procedure is proposed to invert the source function from the ground vibrations observed at array. A dynamic coupled train-track-3D ground model is adopted to calculate the vibrations from given PSD. The Micro-Genetic Algorithm including the operators of the tournament selection, the uniform crossover and the re-initialization together with an elitist strategy is schemed to the inversion. The object function is designed as minimum of the sum of residua between calculated and observed ground vibration acceleration levels of 18 center frequencies, at 4 ground points and twice trains. The result shows that the ground vibration acceleration levels calculated from the obtained excitation source function agree with those from the observed data quite well, even for an additional point where the observed data have never been adopted in the inversion process.

Abstract: The building vibration induced by train loads has aroused people’s great attention. Many investigations have been carried out by many researches in order to evaluate the effect of train-induced vibration on environment. But they have not shown the reason why enlarged vibration region exist in front of a building. In this paper, building structure vibration induced by train loads was analyzed by numerical simulation method performed by ANSYS. Based on numerical results, it’s concluded that the reason for this phenomenon that enlarged vibration region may exist in front of a building is the result that incident wave and the reflected wave superpose mutually. Subsequently, the influence of barrier depth on the enlarged vibration region is also discussed.