GEOE 413 Lecture Notes - Lecture 15: Plane Stress, Commonwealth Scientific And Industrial Research Organisation, Strain Gauge
20 Nov 2016
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Document Summary
When max and min stresses are both high the rock tends to not go anywhere: sig 3 confinement, sig 1 sig 3 tends to make it fail. Stress measurement: most important factor in models, usually guessed at. Every major tunneling dispute in deiderich"s 15 years consulting has involved in situ stress. Stress measurement at tunnel depth during construction can help confirm. Non vertical stresses are not always consistent. The horizontal stress ratio is rarely 1:1 for deep rock tunnels in competent rock. Lower bound magnitude of horizontal stress can be estimated by poisson effect: Simplistic interpretation; tectonic forces are not considered. Alternative model by sheorey (1994) based on shell earth model. Prediction based on regional data, tectonic interpretation. Modelling can be used to combine tectonics with topography. Local tests from within tunnel should be specified as soon as target ground is encountered. Plate tectonic forces: ridge push, slab pull, basal drag: regional. Geological features: faults, hard and soft inclusions.
