3oA

Crushing and grinding

772125 COMMINUTION AND STRUCTURAL CHANGES IN A JET MILL

Me~hart, M; Miskiewicz, L Powder Technol, VIS, N2, Nov-Dec 1976,

P261- 266

Discusses cha~es in the structure of the mat- erial which may take place with the highly intensive cnmm~nntion occurring in a Jet mill. Tests showed changes in the crystal structure anl internal energy content, and it is sugges- ted that this mechanochemical activation must be considered in the further ~rocessing of the ground material.

772126

Cutting

IMPACT I:'ENETROMIS'A'.~el FOR ASSESSING THE CUF2ABILITY OF SC~ ROCKS

Hudson, J A; Drew, S D Transport and Road Research Lab, lab report

685, 1976, 32P

Discusses development of the pem~trcmeter in which a 76 mm hardened steel cone is fired into the rock by a cartridge hammer and the depth of penetration is recorded. The resulting values of penetration strength are closely related to the cutting forces. It is likely that the penetrometer can be used for assessing cattability or general quality of amy soft rock with a com!m~essive strer~ between i and 15 MN/sq m. Time taken for measurements will be significantly reduced with an integrated version of the penetrc~eter. Tunnel face ird~ing data obtained at Chinncr, the Channel turmel and the K/elder experimentsl tunnel are discussed.

Rock and Soil Improvement Techniques

772127 PHILOSOPHY OF GROUND CONTROL. A BRIDGE ~-A~EEN THEORY AND PRACTICE

Morrison, R G K Montreal: McGill Univ, 1976, 196P

Revised edition of the book first published in 1970, includes sections on: rocks and rock masses, stresses and mine openings, ground control facilities, the operating spec~, stopimg methods, and rock bursts.

772128

Bolts and anchors

LOAD-DEFLEXION CHARAC~ISTICS OF A DEEP RIGID ANCHC~ IN AN ELASTIC MEDIUM

Selvadurai, A P S Geo%echnique, V26, h%, 1976, P603-612

The axially symmetric problem of an infinite elastic solid containing a bonded symmetrically loaded sl~heroidal rigid inclusion considered here is of interest in studying the time-inde- pendent load-deClection characteristics of deep rigid anchors embedded in cohesive soil

or rock. From the load-displacement relationahi; obtained using Boussinesq's three-function approach, it is possible to recover solutions to anch~s with spherical, circular c~ elon- gated shapes.

772129 RESIN ANCHORED BOLTS BOOST SAr%'I'% AND PRODUC- TIVITY

Coal Min Froc, VI3, Nil, Nov 1976, P54-55

Briefly describes the use of the Fasloc system at a West Virginia coal mime. The polyester resin, mixed with catalyst during installation, sets in approximately 60 sec and maximum hol- ding strength is attained in 5 rain. Bolts are mostly 4ft installed on 4ft centres, although some 6ft bolts are also used.

772130 PRODUCTS TO FACILITATE ROOF CONTROL Coal Min Proc, V13, Nil, Nov 1976, P60-62

A product survey including roof drills, roof bolters, bolts, rebars, resin cartridges, drill bits etc.

772131 BASIC PRINCIPLES OF ROOF BOLTING Mesa, V1, E%, March-Alm~il 1976, P21-24

772132 INVESTIG~ION OF THE ~CTS OF THRUST AND HARDEX~ED WASHERS ON THE INST~LTrn TENSION OF A ROOF BOLT

Sawyer, S G; Karabin, G J; Debevec, W J US Mining Enforcement and Safety Administra-

tion informational report i031, 1976, 18P

Reports lab tests using 30in bolts with flat, bell and donut plates anchored with ball type expansion shells in a specimen of IrzLiana limestone. It was found that the application of thrust severely reduced the tension at which the bolts were installed, and that the use of hardened washers increased considerably the consistency of the installation of the bolts.

772133 COMPARATIVE EVALUATION OF COnVENtIONAL AND RESIN BOLTIND SYSTEMS

Karabin, G J; Debevec, W J US Mining Enforcement and Safety Administra-

tion informational report 1033, 1976, 22P

Reports a comparative investigation using strain gauged resin bolts, compression pads, and differential sag stations installed during the mining cycle to generate load characteris- tics sand roof stability data s and sdditional investigations have ;roduced optimum install- ation parameters of the 2 systems including the effectiveness of thrust/torque controls for conventional bolts and various bolt/hole diameter combinations for fully grouted rods.

772134 DESIGN AND CONSTRUCTION OF A STRAIN-GAGED RESIN BOLT FOR THE ME~N9 OF IN-SITU AXIAL LOADS

Sawyer, S G; Eakin, G L US Mining Enforcement and Safety Administra-

tion informational report 1039, 1976, 17P

The bolt consists of a straln-gau6ed fin diam- eter resin bolt that can be made in varying lez~ths up to 5f% and when grouted in i-3/8in holes in the mine roof can record in situ axial loads st 3 preselected locations along the bolt's shaft. Half wheatstone bridges pow- ered by an intrin~cally safe strain box giv~ readings independent of the effects of tempera- ture humidity, bending ard torsion.