Ground consolidating and sealing

Ground consolidating and sealing

31A Rock and Soil Reinforcement and Support See also: 891160 891246 Geotechnicni engineered construction Schlosser, F; Magnan, J P; Holtz, R D Proc l...

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31A

Rock and Soil Reinforcement and Support See also: 891160 891246 Geotechnicni engineered construction Schlosser, F; Magnan, J P; Holtz, R D Proc l leh International Conference on Soil Mechanics and Fou~lation Eqi~ering, San Francisco, 12-16 August 1985 VJ, P2499-2539. Publ Rotterdam: A A Balkema, 1988 A review of three topics is presented. The influence of excavations on existing structures is discussed, considering large excavations and trenches, shallow tunnels, and embankments. Soil shear strength improvement using rod or grid reinforcement, fibres or small plates, dynamic substitution, jet grouting, or soil nailing is next examined. Finally, geotextiles and their applications to embankments, dams, slopes, and roads are discussed. 151 refs.

Bolts and anchors See also: 891197 891247 Cyclic bchaviour of plate anchors: note Ponniah, D A; Finlay, T W Can Geotech J V25. N2, May 1988. P374-381 The behaviour of plate anchors subjected to long term cyclic loading was studied. Model load tests were carried out in kaolin consolidated from a slurry under various mean loads and cyclic amplitudes. The anchors did not fail when load cycled up to 50% of drained ultimate pullout capacity, and, under recycling loading, up to 70% was possible before failure.

Direct rock support methods See also: 891379 891250 Evaluation of shield support performance by numerical analysis Peng, S S; Hsiung, S M; Jiang, Y M Min Sci Technoi V7, NI, May 1988, P19-30 Use of the finite element method to analyse the performance of different types of shield supports was investigated. Ten types of shield with varying number, orientation and location of legs were simulated in a 2D finite element program. Control of face convergence, prevention of premature roof fall along the longwall face, and avoidance of excessive stress concentration around the top of the base plate were analysed, Results are used to recommend suitable shield support for various roof conditions. 891251 Choice of support and roadway drivage in hard rock mining Maloszewski, J; Szyndler, J; Mateja, J Proc 13th World Mining Congress, lmpro~mcnt of Mine Productivity and O~erall Economy by Modern Technology, Stockholm, June 1987 V2, P837-845. Publ Rotterdam: A A Balkema, 1987 Polish coal mines are becoming deeper, and roadways in heave prone rock and high in situ stress are encountered. Dinting of the floor behind the face has negative effects on drift stability. Arch supports with steel floor bars have proved successful in controlling heave and a series of closed profile arches of different strengths has been developed. Tunnelling is by conventional methods with the rock mechanics aspects of heave taken into account.

Grouting

891248 Hybrid boundary element-finite element method of stress analysis for bolt-reinforced inhomogeneous ground Peng, S S; Guo, L B Min Sci Technol V7, NI, May 1988. PI-18

891252 Ground consolidating and sealing Comely, W Min Mag July 1988, P38-40

Two numerical methods are combined to simulate the behaviour of bolted mine strata. The stress distribution along each bolt is related to its deformation in both axial and lateral directions, based on the minimum principle of potential energy of the bolt, allowing an improved finite element formulation for grouted bolts, which can determine the internal loads applied to the surrounding rocks. Rock inhomogeneity and the effects of creating openings are simulated by an indirect formulation method using boundary and interface elements. Examples are used to illustrate efficiency of the method.

Polyurethane grouts are made by reacting polyisocyanates with a polyol. When injected into wet strata, polyisocyanates react with the water to produce carbon dioxide as one reaction product, resulting in a sealed layer graduated from foam to a hard watertight barrier. They are used to consolidate weak strata or seal water inflow in mines and tunnels. Pu grouts can yield, penetrate small fissures, can have controlled reaction rates, have adhesive properties, and are simple to place. There are, however, flammability drawbacks, and they cannot be used as surface coatings or to fill large voids.

Shotcrete

Reinforced earth

891249 Contribution concerning the rheologic hehaviour of shotcrete (In German) Schubert, P Felsban V6. N3, Aug 1988, t'50-53 A method to establish a relationship between dilation of and strains in shotcrete, considering parameters such as elastic deformation, plastic and delayed elastic creep, and development with age, temperature and shrinkage. The calculated values agree with test results. The method allows evaluation of loads exerted on a shotcrete layer from initial application.

See also: 891296 891253 Effects of reinforcing elements on the behavior of weakly cemented sands: note Li, L; Mitchell, R Can Geotech J V25. N2, May 1988, P389-395 Plane strain tests were undertaken on cemented sands containing a variety of reinforcement inclusions, aiming to reduce cement usage and improve performance of mine backfills.

© 1989 Pergamon Press plc. Reproduction not permitted