Saturation Effects on Disc Cutting of Sandstone

Abstract

A plethora of work has been conducted to study the process of rock fracture beneath a cutting tool from analytical, numerical, and experimental perspectives in connection with the performance prediction of mechanical excavators like tunnel boring machines (TBM), roadheaders, mobile miners, raise and shaft borers etc. One aspect that deserves more attention is the rock saturation effect on the cutting performance of mechanical excavators. The current investigative study focuses on finding the differences in the cutting performance of disc cutters when cutting in dry and saturated rocks. A series of full scale laboratory linear rock cutting tests was carried out with a long bladed single disc cutter (292 mm diameter, 11mm wide constant cross-section blade) on dry and water saturated sandstone blocks using a linear rock cutting machine (LRCM). Normal, rolling and side forces were measured while varying cut spacing and cutter penetration. The results obtained from 58 data passes incorporating 600 data cuts were used for computation of performance related parameters. Significant reductions in the cutting forces and specific energy (SPE) were observed between dry and saturated rock cutting experiments indicating that cutting saturated rock of this type is more energy efficient than cutting dry rock. Reductions of 10% and 8.4% in the nominal SPE (based on theoretical excavated volume) and actual SPE (based on mass of broken chips) values respectively were observed when cutting in saturated rock as compared to the dry cutting. A drop in the cutting coefficient (CC) at deeper penetrations in saturated experiments was contrary to the usual rise in CC at deeper penetrations in dry rocks, suggesting a possible role of excess pore water pressure facilitating the cutting process at deeper penetrations (where high normal and rolling forces are expected). There were reductions of 27.5%, 44% and 48% in the normal, rolling and side forces respectively, when cutting in saturated rocks as compared to cutting in dry rocks.

Meeting Name

45th US Rock Mechanics / Geomechanics Symposium (2011: Jun. 26-29, San Francisco, CA)

Department(s)

Geosciences and Geological and Petroleum Engineering

Sponsor(s)

American Rock Mechanics Association (ARMA)

Keywords and Phrases

Cutting Coefficients; Cutting Forces; Cutting Performance; Cutting Process; Disc Cutter; Dry Cutting; Dry Rocks; Energy Efficient; Excess Pore Water Pressure; Full Scale; Performance Prediction; Roadheaders; Rock Cutting; Rock Fractures; Rolling Force; Saturated Rock; Saturated Sandstones; Saturation Effects; Side Force; Specific Energy; Tunnel Boring Machines; Construction Equipment; Cutting Tools; Earth Boring Machines; Energy Efficiency; Excavation; Excavators; Experiments; Fracture; Machinery; Rock Mechanics; Sandstone

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2011 American Rock Mechanics Association (ARMA), All rights reserved.

Publication Date

01 Jun 2011

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