902266 Interactive finite element mesh generation for three dimensional tunnel analysis Mertz, W G; Swoboda, G A Proc Symposium on Computer Aided Design and Monitoring in Geoteclmical Engineering, Bangkok, 3-6 December 1986 P609-628. Publ Bangkok." AIT, 1986

The FEMCAD program is described, which was developed to generate three dimensional finite element meshes for tunnel analysis. It was originally designed for use with the F INAL program at lnnsbruck University, but can be applied to other programs with minor changes. It enables mesh generation in a matter of hours, rather than days.

902267 Interactive computer aided methods for the design and monitoring of embankment dams Silver, M L; Riccioni, R Proc Symposium on Computer Aided Design and Monitoring in Geotecknical Engineering, Bangkok, 3-6 December 1986 P747-765. Publ Bangkok: AIT, 1986

Application of computer technology has removed the need for time consuming manual calculations in dam engineering. The EDDIS system (Embankment Dam Design Integrated Software) is described. It contains modules for positioning the structure, definition of dam axis, foundation excavation, defi- nition of embankment cross section, calculation and prelimi- nary design drawings, and static and dynamic analysis. The monitoring program MIDAS (Management of Information for Dam Safety) is also illustrated.

Rock Breakage and Excavation

Drilling

902268 Use of single-cutter data in the analysis of PDC bit designs: part 1 - development of a PDC cutting force model Glowka, D A J Pet Technol 1/41, N8, Aug 1989, P797-799, 844-849

A conceptual model of the rock drag cutting process is devel- oped for application to PDC drill bits. Single cutter laboratory tests were carried out using a variety of rock types, cut depths, and cutter wear states. Two distinct modes of wear were iden- tified, one for soft plastic rocks, the other for hard brittle rocks. A method is developed to use single cutter data to pre- dict forces arising when cuts overlap because of close lateral cutter spacing. Water jet assistance has significant effects on cutter forces.

902269 Use of single-cutter data in the analysis of PDC bit designs: part 2 - development and use of PDCWEAR computer code Glowka, D A J Pet rechnol V41, NS, Aug 1989, P850-859

The Fortran code PDCWEAR was developed to analyse per- formance and wear of PDC rock drill bits. A cutter interaction model is generalized to predict individual cutter forces across a bit face of arbitrary design. These forces are used to predict wear-fiat temperature, wear rate, weight on bit, drilling tor- que, and bit life. PDCWEAR is demonstrated analysing effects of bit profile, number of cutters, rotary speed, water jet assistance, and cutter wear mode.

98A

902270 Drilling intelligence and automation Peck, J; Scoble, M; Payton, D Miner Resour Engng V2. ~ . April-June 1989, P109-122

Surface rotary blasthole drilling has been monitored using microprocessor based equipment. Experience at the Fording River Coal Mine, Canada. is described. The behaviour of the drill under various operational and geological conditions is outlined. Based on this data. a control strategy can be devel- oped using knowledge based systems to characterise the ground conditions and thence control drill automation.

902271 Momentum and energy processes during jackhammer operation Pang, S S; Goldsmith, W Rock Mech Rock Engng V22, N3, July-Sept 1989, P205-209

An analytical model has been developed of the motion of the bit of a pneumatic jackhammer (percussion drill) and the forces at its tip as it penetrates a target. It assumes energy is transmitted as a one-dimensional longitudinal wave. Numeri- cal output is compared to data on force and indentation histo- ries from experiments penetrating a jackhammer with five different tip shapes into Sierra granite. Good correspondence is seen between analytical and laboratory results.

902272 Prediction of wellbore trajectory considering bottomhole assembly and drill-bit dynamics Brakel, J D; Azar, J J SPE Drilling Engng V4, N2. June 1989. P109-118

A three dimensional finite element model is presented to simu- late transient dynamic behaviour of a bottom hole assembly (BHA) during drilling. To ensure correct boundary conditions at the rock/bit interface,interaction effects for roller-cone and PDC drill bits are included. Directional tendencies in horizon- tal and vertical planes can be studied. Effects of hole inclina- tion, weight on bit, rotary speed, and bit/stabilizer clearance are presented for a typical BHA. Predictions are compared with field case data. Geological effects are not included in the model.

902273 Drag-bit performance modeling Warren, T M; Sinor, A SPE Drilling Engng V4, N2. June 1989, P119-127

Models of forces required to remove a fixed volume of rock with a single cutter have been extended to PDC bits to predict weight on bit and torque for a given penetration rate. Labora- tory tests were carried out using four different rocks (shales, sandstone, marble) and four bit designs. Both reaming tests using only the peripheral cutters and drilling tests were used. Model predictions agreed well with measured data.

902274 Drag bit wear model Sinor, A; Warren, T M SPE Drilling Engng V4, N2. June 1989, P129-136

A performance model for PDC bits has been modified to include prediction of wear on individual cutters. Both abrasive wear and wear by dynamic forces (chipped, broken or lost cutters) which can cause bit imbalance are considered. Predic- tions consider cutter geometry, velocity and temperature, rock type and forces on the cutter. Measured wear on a field-worn PDC bit is compared with predictions. Laboratory tests show bit imbalance leads to reduced penetration rate, oversize holes, and increased cutter wear and breakage.

~, 1990 Pergamon Press plc. Reproduction not permitted