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Trenchless drainage with textile percolation materials
124A 922400 Experimental investigations of braced excavations deformations and adjacent building settlements caused by then Rayuk, V F; Matveyeva, N M Proc Ninth Danube European Conference on Soil 3,lechanics and Foundation Engineering, Budapest, 2-5 October 1990 P123-127. Publ Budapest: Akademiai Kiado, 1990 Wall movements and bending moments, and settlements of an adjacent foundation were monitored during construction of a 10m deep, 8.5m wide braced excavation in sandy soils. The wall moved about its base until excavated depth reached about 8m, when rotation about the support was seen. The accompanying soil displacement was the major cause of foundation settlement. Model tests were carried out to obtain more information on soil movement behind the wall, boundaries of the deformed soil zone, and distribution of the settlement behind the wall. Results are compared to theoretical values.
922401 Anchorage of diaphragm wall in Budapest Rozsa, L; Nemeth, G; Bohn, I Proc Ninth Danube European Conference on Soil Mechanics and Foundation Engineering, Budapest, 2-5 October 1990 P129-135. Publ Budapest: Akademiai Kiado, 1990 A 15m deep reinforced concrete retaining wall was constructed in a soil profle of fill/sand to 3.3m, peat to 6.2m, and coarse sand to 11.3m, then clay. A basement excavation was carried out behind the wall, which was supported by 18m long grouted, prestressed anchors, set at depth 2.8m and at 30 deg to the horizontal. 4-5mm of movement was registered at the anchor level after excavation, about half that expected. Adjacent surface settlement was l-7mm. Design and constructional aspects are discussed. 922402 Centrifugal investigations of cohesive soil lateral pressures acting on enclosing structures Shcherbina, V I Proc Ninth Danube European Conference on Soil Mechanics and Foundation Engineering, Budapest, 2-5 October 1990 P137-142. Publ Budapest: Akademiai Kiado, 1990 The development of lateral pressures in backfill, especially for cohesive materials, is determined largely by placement conditions and methods. Experimental work has indicated that lateral pressures up to twice those in equivalent cohesionless fills are possible. To avoid the need to construct many full scale fills, centrifuge tests were used to examine behaviour of cohesive backfills under realistic working stress levels. Influence of backfill density and water content (hence construction procedure) was examined. The use of a layer of cohesionless material adjacent to the wall will lower horizontal pressure by about 25%.
Construction methods 922403 Augers drill a positive niche Sanda, A P Coal V96, ?(8, Aug 1991. P48-51 Auger mining was first used in the 1940s, but has never been widely adopted. Current machines have diameters up to 1.3m, and can penetrate over 150m with recovery up to 75%. They have found application in mining small seams which are otherwise uneconomic. Examples are presented. A compromise is necessary between recovery and daily output when deciding on penetration depth.
Groundwater problems See also: 9~2/~5 922404 Island Copper south wall pus&back project Findlay, R B: Robcrtson, R B: O'Kane, K P lnt J Surf 31:.n V5. .V1. 1991, P25-32 Large ore reserves underly a tidally active waste dump at the Island Copper open pit mine, Vancouver Island. To enable exploitation, a diaphragm wall of approximate area 30000sq m and thickness about lm was constructed. The process involved excavation through some 30m of dump, beach, and till using a clamshell bucket, and chiselling a rock socket in bedrock, all under bentonite. Contiguous wall panels of low strength plastic concrete were tremied in. The 90m pushback increases pit life by 4 years. Performance and monitoring to date are described. 922405 Ground water restoration in mined areas Garlanger, J E; Shrestha, R K Min Engng V43, N9, Sept 1991, P1159-1164 Phosphate mining in Florida results in the removal of the surfcial aquifer, plus the top of the uppermost confining unit in some cases. The surrounding unmined area will continue to dewater until the mine is reclaimed. Usual reclamation options are filling the pit with hydraulically transported clay or sand waste, or levelling spoil piles and allowing natural waters to fill the remnant pit. Implications of these options on ground and surface water resources of the affected watershed, groundwater recharge, water table, and base flow and runoff to local schemes are examined with reference to case study data. 922406 Geotextile intrusion into geonets Hwu, B L; Koerner, R M; Sprague, C J Proc 4th International Conference on Geotextiles, Geomembranes and Related Products, The Hague, 28 May-I June 1990 V1, P351-356. Publ Rotterdam: A A Balkema, 1990 Geotextiles are used to support the soil over the apertures between ribs of geonet drains. Soil pressure forces the geotextile into the flow zone (intrusion) and reduces the flow rate. The extent of intrusion has been examined in the laboratory for a variety of needle punched nonwoven geotextiles, with soil type, pressure, and time varied. Flow rate was reduced significantly (39-88%). Stiffening the geotextile leads to some improvement. Creep of the geotextile is important to long term intrusion. 922407 Trenchless drainage with textile percolation materials Muzel, F; Garbe, D; Bottcher, P; Gora, A Proc 4th International Conference on Geotextiles, Geomembranes and Related Products, The Hague, 28 May-1 June 1990 VI, P357-360. Publ Rotterdam: A A Balkema. 1990 Percolation drains of granular materials are expensive and time consuming to construct. They have been replaced in many instances by plastic drainage pipe, which is installed using a plough-like machine. Textile percolation tape or cord is simultaneously installed to improve water flow to the drain. Equipment and techniques are illustrated.
© 1992 Pergamon Press Ltd. Reproduction not permitted
922401 Anchorage of diaphragm wall in Budapest Rozsa, L; Nemeth, G; Bohn, I Proc Ninth Danube European Conference on Soil Mechanics and Foundation Engineering, Budapest, 2-5 October 1990 P129-135. Publ Budapest: Akademiai Kiado, 1990 A 15m deep reinforced concrete retaining wall was constructed in a soil profle of fill/sand to 3.3m, peat to 6.2m, and coarse sand to 11.3m, then clay. A basement excavation was carried out behind the wall, which was supported by 18m long grouted, prestressed anchors, set at depth 2.8m and at 30 deg to the horizontal. 4-5mm of movement was registered at the anchor level after excavation, about half that expected. Adjacent surface settlement was l-7mm. Design and constructional aspects are discussed. 922402 Centrifugal investigations of cohesive soil lateral pressures acting on enclosing structures Shcherbina, V I Proc Ninth Danube European Conference on Soil Mechanics and Foundation Engineering, Budapest, 2-5 October 1990 P137-142. Publ Budapest: Akademiai Kiado, 1990 The development of lateral pressures in backfill, especially for cohesive materials, is determined largely by placement conditions and methods. Experimental work has indicated that lateral pressures up to twice those in equivalent cohesionless fills are possible. To avoid the need to construct many full scale fills, centrifuge tests were used to examine behaviour of cohesive backfills under realistic working stress levels. Influence of backfill density and water content (hence construction procedure) was examined. The use of a layer of cohesionless material adjacent to the wall will lower horizontal pressure by about 25%.
Construction methods 922403 Augers drill a positive niche Sanda, A P Coal V96, ?(8, Aug 1991. P48-51 Auger mining was first used in the 1940s, but has never been widely adopted. Current machines have diameters up to 1.3m, and can penetrate over 150m with recovery up to 75%. They have found application in mining small seams which are otherwise uneconomic. Examples are presented. A compromise is necessary between recovery and daily output when deciding on penetration depth.
Groundwater problems See also: 9~2/~5 922404 Island Copper south wall pus&back project Findlay, R B: Robcrtson, R B: O'Kane, K P lnt J Surf 31:.n V5. .V1. 1991, P25-32 Large ore reserves underly a tidally active waste dump at the Island Copper open pit mine, Vancouver Island. To enable exploitation, a diaphragm wall of approximate area 30000sq m and thickness about lm was constructed. The process involved excavation through some 30m of dump, beach, and till using a clamshell bucket, and chiselling a rock socket in bedrock, all under bentonite. Contiguous wall panels of low strength plastic concrete were tremied in. The 90m pushback increases pit life by 4 years. Performance and monitoring to date are described. 922405 Ground water restoration in mined areas Garlanger, J E; Shrestha, R K Min Engng V43, N9, Sept 1991, P1159-1164 Phosphate mining in Florida results in the removal of the surfcial aquifer, plus the top of the uppermost confining unit in some cases. The surrounding unmined area will continue to dewater until the mine is reclaimed. Usual reclamation options are filling the pit with hydraulically transported clay or sand waste, or levelling spoil piles and allowing natural waters to fill the remnant pit. Implications of these options on ground and surface water resources of the affected watershed, groundwater recharge, water table, and base flow and runoff to local schemes are examined with reference to case study data. 922406 Geotextile intrusion into geonets Hwu, B L; Koerner, R M; Sprague, C J Proc 4th International Conference on Geotextiles, Geomembranes and Related Products, The Hague, 28 May-I June 1990 V1, P351-356. Publ Rotterdam: A A Balkema, 1990 Geotextiles are used to support the soil over the apertures between ribs of geonet drains. Soil pressure forces the geotextile into the flow zone (intrusion) and reduces the flow rate. The extent of intrusion has been examined in the laboratory for a variety of needle punched nonwoven geotextiles, with soil type, pressure, and time varied. Flow rate was reduced significantly (39-88%). Stiffening the geotextile leads to some improvement. Creep of the geotextile is important to long term intrusion. 922407 Trenchless drainage with textile percolation materials Muzel, F; Garbe, D; Bottcher, P; Gora, A Proc 4th International Conference on Geotextiles, Geomembranes and Related Products, The Hague, 28 May-1 June 1990 VI, P357-360. Publ Rotterdam: A A Balkema. 1990 Percolation drains of granular materials are expensive and time consuming to construct. They have been replaced in many instances by plastic drainage pipe, which is installed using a plough-like machine. Textile percolation tape or cord is simultaneously installed to improve water flow to the drain. Equipment and techniques are illustrated.
© 1992 Pergamon Press Ltd. Reproduction not permitted