Experimental study on rolling rock boulder and its analysis

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Experimental study on rolling rock boulder and its analysis

 

Author: Lam, Chung-wing
Title: Experimental study on rolling rock boulder and its analysis
Degree: M.Sc.
Year: 2001
Subject: Rockslides
Rock slopes
Slopes (Soil mechanics)
Hong Kong Polytechnic University -- Dissertations
Department: Multi-disciplinary Studies
Dept. of Civil and Structural Engineering
Pages: vi, 83, [87] leaves : ill. (some col.) ; 30 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b1569119
URI: http://theses.lib.polyu.edu.hk/handle/200/1067
Abstract: This project presents some experimentally evaluated data for a rockfall modeling. In particular, the rolling and bouncing phases of rockfall are addressed. Through the observation of the rolling movement of boulder samples on an artificially made sloping platform, the effect of sloping angle, asperity of slope surface, shape and size of boulders to the translational rolling velocity of boulders on slope were determined. The rolling patterns of the boulder samples, both along and in lateral direction of the slope, had been recorded. Based on the results, it was noted that there is no deterministic approach to figure out the movement of the boulder on slope. In many of the previous experimental studies of rockfall, the effect of the boulder's strength (variation of material's elastic modulus), shape and size to the coefficients of restitution between rock boulder and slope surface during bouncing had been broadly investigated. However, such determination of the coefficients of restitution had usually based on the boulder's translational velocity at the moment before and after impact. In real situation, it can be observed that a falling rock boulder is usually accompanied with rolling. Thus, the boulder itself consists of kinetic energy due to not only translation but also rotation during its movement. In this experiment, the effect of rotational energy had also been taken into account during the determination of energy coefficient of restitution at impact. From the test results, it is noted that rotation of boulder has significant effect on the tangential velocity after impact. The tangential velocity was found increased after impact, hence the coefficient of tangential coefficient of restitution. The effect is because the lost of rotational energy of boulder during impact is partly transferred into the translational energy. The rebound pattern of boulder samples and deformations on the bouncing platform caused by punching of boulders during impact had also been recorded in the experiment. From the record, it is recognized that the amount of energy lost during impact is directly related to the mode of impacts. In addition, the data collected in the experiment had also been used to compare and correlate with the test results obtained from other field and experimental tests.

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