A project report submitted to the Faculty of Mining Engineering, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering. / A strategy to determine the probability that a mining induced seismic event will occur with magnitude which exceeds some specified value within a given time is investigated. The model allows for a non-linear frequency-magnitude relationship and a Poissonian distribution of seismic events in time. The procedure is also independent of the method of mining and of the mining geometry. The model was applied to clusters of various sizes) starting from small areas on a single reef and ending up with the entire mine as a single entity. It was shown that the model works well with large populations of events, but to be successful with small clusters, the retention of the Poisson distribution is too restrictive and a non-stationary model of seismicevent occurrence in time will have to be developed. / AC2018

A project report submitted to the Faculty of Mining Engineering, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering. / A strategy to determine the probability that a mining induced seismic event will occur with magnitude which exceeds some specified value within a given time is investigated. The model allows for a non-linear frequency-magnitude relationship and a Poissonian distribution of seismic events in time. The procedure is also independent of the method of mining and of the mining geometry. The model was applied to clusters of various sizes) starting from small areas on a single reef and ending up with the entire mine as a single entity. It was shown that the model works well with large populations of events, but to be successful with small clusters, the retention of the Poisson distribution is too restrictive and a non-stationary model of seismicevent occurrence in time will have to be developed. / AC 2018

The problem of fitting a material property of the earth to a certain model by analysing a returned seismic signal is investigated here. Analysis proceeds with methods taken from the theory of inverse problems. Seismic wave inversion is tack- led by minimisation of the objective function with respect to the model parameters. Absorbing boundary conditions are implemented using an exponentially decaying ansatz. / Physics / Ph. D. (Physics)

The problem of fitting a material property of the earth to a certain model by analysing a returned seismic signal is investigated here. Analysis proceeds with methods taken from the theory of inverse problems. Seismic wave inversion is tack- led by minimisation of the objective function with respect to the model parameters. Absorbing boundary conditions are implemented using an exponentially decaying ansatz. / Physics / Ph. D. (Physics)

The development of improved models of seismic diffraction is assisted by the availability of accurate scattering data. An acoustic scatter-mapping system was developed for the purpose of providing such data rapidly and at low cost. This system uses a source-receiver pair suspended on a trolley over the structure to be mapped. Signal generation, acquisition, processing, and plotting are performed on an AT-compatible microcomputer and a laser printer. The entire process can be performed in an automated manner within five hours, generating scatter-mapping plots in a format familiar to the geophysical industry. The system hardware was similar to those of Hilterman [1] and others referenced by him, but used a controlled source transducer. The available processing power of a microcomputer allowed the use of a 1 to 15 KHz swept-frequency source signal, similar to that used in Vibroseis and Chirp Radar, which is later crosscorrelated with received signal to provide precise scatter-mapping data for the target structure. Several examples of theoretical and experimental acoustic scatter-mappings are provided for comparison. The novelty of this system lies in its use of a swept frequency source signal. While common in the fields of seismology and radar, swept frequency source signals are new to the area of acoustic scatter mapping. When compared to a similar system using a pulsed source signal, this system produces a better controlled source signal of greater energy, resulting in a more useful resultant signal and better mapping characteristics. The system was able to map scattering from features in the target structure smaller than one percent of the crosscorrelated source signal's 37 mm dominant wavelength. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1981. / Microfiche copy available in Archives and Science. / Bibliography: leaves 273-291. / by Mai Yang. / Ph.D.

Este trabalho tem como objeto o estudo do efeito da rigidez de pilar parede no comportamento estrutural de edifícios de concreto armado submetidos a sismos. Foram consideradas as premissas da norma brasileira ABNT NBR15421:2006, que apresenta os critérios para projeto de estruturas resistentes a sismo. A análise linear com emprego dos métodos da norma - método das forças horizontais equivalentes, método espectral e histórico de aceleração no tempo - foi aplicada em edifícios com dois tipos de sistemas estruturais, sendo eles pórtico de concreto e sistema dual pórtico de concreto e pilar parede. Os resultados foram analisados nos pórticos de extremidade das estruturas nos sentidos longitudinal (x) e transversal (y), comparando-se os deslocamentos de cada pavimento e esforços cortantes, momento fletor e normal nas bases dos pilares. A comparação foi realizada entre os três métodos aplicados e os sistemas estruturais analisados. / The aim of this work is to study the stiffness effect of wall columns on structural behavior of reinforced concrete buildings subjected to seismic action. The premises of the Brazilian standard ABNT NBR14521:2006 were considered, which presents criteria for earthquake resistant design of structures. The linear analysis employed the methods of the Brazilian standard - equivalent static load method, response spectrum analysis and time history method - were applied to buildings with two types of structural systems, namely concrete frame and dual system concrete frame and wall columns. The results were analyzed in edge frames structures in the longitudinal and transverse directions, comparing the displacement of each floor and shear, bending moment and axial forces on the bases of the columns. A comparison was made between the three methods applied and the structural systems analyzed.