Drilling holes in hard rock for excavation and mining construction is generally carried out with rotary percussion drills. While advances have been made in percussion drilling in the past twenty years including tungsten carbide inserts, hydraulic actuation and water jet process is till classified as slow and expensive. New concepts of drilling with high pressure water jets containing abrasives have shown considerable promise and could significantly improve productivity in rock drilling. The research program will involve the design, fabrication and testing of a novel abrasive/water jet drill capable of drilling in hard rock at high speed with no moving mechanical components. The design incorporates a drill head with a high pressure nozzle to form a water jet. Abrasives are fed into the jet in the spreader section after the high velocity jet has been formed. The design and fabricaiton of the drillhead will be evaluated to determine the drilling parameters including water pressure, water flow rate, abrasive type, abrasive flow rate, abrasive size and stand-off distance for different penetration rates. Flow Industries have extensive experience in developing abrasive water jet cutting systems for a variety of industrial applications including turning, milling, cutting and surface finishing. The principal investigator has over 15 years experience with water jets and is a leading authority in the field. We anticipate a successful development which could lead to major cost reduction in hard rock drilling operation on an international scale. An award is recommended. 8612876 RUDNICKI This is a cooperative research with the Department of Energy (DOE). DOE provides the facility and technical personnel to perform experimental verfication for the analysis on shear localization of geo-materials. The research applies recent solid mechanics advances to understand shear localization behavior and develope a verified approach to predict the stability of geo-materials such as rock and concrete structures. The main goal of this work is to understand the physical process of strain localization in geo-materials and provide a theoretical framework for the extrapolation of laboratory observations to applications. The research performs comprehensive studies on shear localization in rocks and other geo-materials that exhibit sensitivity of inelastic deformation and inelastic volume change. The studies combine theoretical analyses with computational and experimental work. Improved constitutive relations for multiaxial and inelastic deformation will be formulated and a framework will be developed for the use of constitutive models in numerical codes. Specifically, shear rupture in pressure-sensitive and inelastically compressible solids will be investigated based on models involving bifurcation from homogeneous deformation. The investigations of localization will then be use with experimental observations and numerical calculations to study the performance of inelastic constitutive relations for multiaxial deformation of geo-structures. The Principal Investigator is a leader in this area of mechanics research applied to strain localization. This cooperative research is cost effective and addresses a critical problem in Solid and Geomechanics research.
