Showing papers by "Herbert H. Einstein published in 2002"
TL;DR: In this article, a general stereological relationship between distributions of trace length and distributions of discontinuity size (expressed by the major axis length, a, of the ellipse) is derived for area (or window) sampling.
Abstract: This paper presents an approach for estimating the size distributions of elliptical discontinuities. This is an extension of approaches for estimating size distributions of circular discontinuities. By assuming an elliptical shape and changing the aspect ratio k of the ellipses (i.e. the ratio of the major to minor axes), many real discontinuities can be reasonably represented. For elliptical discontinuities, a general stereological relationship between distributions of trace length and distributions of discontinuity size (expressed by the major axis length, a, of the ellipse) is derived for area (or window) sampling. From this relationship, expressions are derived between the mean (μa) and standard deviation (σa) of the discontinuity size, a, and the mean (μl) and standard deviation (σl) of the trace length, l, respectively for log-normal, negative exponential and gamma distributions of discontinuity sizes. Using the derived expressions, the effect of sampling plane orientation on trace lengths is invest...
68 citations
TL;DR: In this paper, the authors present an updating procedure that allows one to refine predictions during construction, which can be used to improve scheduling, resource allocation, financial planning, and so on.
Abstract: The “Decision Aids for Tunneling” are a procedure and computer code that can be used to assess the effect on construction cost and time of geologic/geotechnical uncertainties and uncertainties in the construction process. Previously, it was only possible to make predictions prior to construction. There is, however, a need for updated predictions while construction is in progress. Such predictions can be used to improve scheduling, resource allocation, financial planning, and so on. This article presents an updating procedure that allows one to refine predictions during construction. Updating not only involves replacing the original prediction with actual data from the excavation, but also includes a learning component using information from the actual excavation to arrive at an improved prediction for the unexcavated part of a tunnel.
67 citations
TL;DR: In this article, the authors compare the fracture spacing and trace length simulated by the model with data collected by Billings (1976) in a number of tunnels in the Boston area.
Abstract: The MIT stochastic model for representing fracture patterns has been applied to the Boston area. The model is a geometric-mechanical model, which means that underlying mechanisms are geometrically represented. In this paper the model is calibrated by comparing the fracture spacing and trace length simulated by the model with data collected by Billings (1976) in a number of tunnels in the Boston area. Following this, geometric fracture connectivity is investigated. This is done by recording in the model simulations, the number of interconnected fractures in so called sub-networks and by recording the geometric extents of these sub-networks. The results indicate limited horizontal but large vertical connectivity.
54 citations