187A attributed to use of smooth wheeled rollers on wet, plastic clay fill without effective scarification. Built in shears were formed along these smooth planes during subsequent stages of construction.
excessive. Remedial measures included excavation of tunnels in the slate beneath the toe and constructing a concrete plug and grouting of trap rock.
923374 Evaluation of failure of embankment during heightening Bauduin, C; Molenkamp, F Geoteelmique V41, N3, Sept 1991, P423-435
923378 Design considerations for heightening of existing dams Narayana, V V B; Haridas, C; Joshi, A B
The inner slope of a clay flood embankment on the MeuseRhine delta failed just after completion of broadening and heightening. Classical slope stability analysis at the last loading stage had indicated a factor of safety about 1.15. The geotechnical profile of the site and monitored data during construction are described. Differences between classical assumed behaviour and actual behaviour are examined. The major factor leading to failure was the higher than assumed pore pressures generated during construction.
923375 Foundation treatment at the Tadami dam site lnt Water Power Dam Constr V43, N i l , Nov 1991, P35-36 The Tadami rockfill dam on the Agano river, Japan, is founded on 21m of alluvium over bedrock. Excavation down to bedrock was considered uneconomic. The alluvial deposits of gravel, sand, and silt are dense and interlocked, and a bentonite concrete diaphragm wall was chosen as the foundation treatment. This plastic concrete has mechanical properties compatible with both foundation and dam during its working life. Construction and performance are described.
923376 Design of a tailings disposal facility for the Samatosom Mine, British Columbia Hawley, P M; Stewart, A F Proc 2rid International Symposium on Mine PinnMslg and Equipment Selection,Calgary, 7-9 No~ember 1990 P433-440. Publ Rotterdam: A ,4 Balkema, 1990 A tailings impoundment with ultimate capacity of 800,000 cubic m is planned for the recently commissioned Samatosum Mine. The initial impoundment is a 20m high, homogeneous till dam, with crest length 225m, which will be raised to ultimate height 30m by downstream construction. Site selection, engineering geology, selection of construction method, and water balance are discussed. Construction of intermediate and ultimate embankments, stability and settlement, seepage, and monitoring in this environmentally sensitive area were taken into account at the design stage.
923377 Settlement analysis of Lakhwar Dam foundations Arora, B M; Yadav, S K Proc l ~ m Geoteclmical Conference, 1989, Geoteclmiques of Problematic Soils amt Rocks, gisakimpntnam, 14-16 December 1989 V1, P491-494. Pubi New Delhi: Sarita Prakashan, 1989 The foundation rocks of the 240m high concrete gravity dam consist of slates, quartzites, and limestone, forming the southern limb of a major syncline, intruded by a number of minor basic trap bodies. Foliated slates with low deformation modulus exist beneath the dam toe and vertical differential settlements with respect to existing foundation rocks have been
Proc lmtian Geoteelmical Conference, 1989, Geoteelmiqncs of Problematic Soils and Rocks, VisakhapntMm, 14-16 December 1989 VI, P495-499. Publ New Delhi: Sarita Prakashan, 1989 The raising of an earth dam, part of the composite Som Kamala Amba dam in Rajasthan, is described. Minimising of rehandling was the aim. The central area was extended by an inclined core and the inclined sand filter turned towards downstream. The rock toe was extended in width and the toe drain shifted to maintain internal drainage. Stone pitching on the filter was made thicker and reinforced. Foundation rock was examined and considered adequate. Because of problems where it met the earth dam, the masonry core wall was converted to an additional non-overflow block. Composite dams require special care at the design stage if future heightening is envisaged.
Hydraulic structures 923379 Methods to ensure water tightness for a dry dock founded on fissured reck at Visakhapatmun fishing harbour Sastry, S V L S N; Murty, R N; Rao, T S P Proc Indian Geoteclmical Conference, 1989, Geoteclmiqncs of Problematic Soils and Rocks, YIsakimpatum, 14-16 December 1989 V1, P509-512. Publ New Delhi: Sarita Prakashan, 1989 The 65m long by 21m wide by 6m deep (low tide) structure was founded on fissured and fractured rock at shallow depth, which created problems of potential water ingress. The overcome this, an extensive pressure grouting program was carried out. Curtain grouting beneath the walls and blanket grouting beneath the floor of the structure, plus installation of drainage systems and instrumentation to monitor water flow are described.
92338O l.inin~= and stabillsntion of slopes for channels in Black Cotton soils Datye, K R Proc 6th lmernationai Conference on Expansive Sot'Is, New DelM, 24 No~mber-4 December 1987 V2, P626-629. Pubi Rotterdam: A A Balkema, 1991 Linings for hydraulic structures in expansive Black Cotton soils are discussed. CNS layers can be used to provide a surface load to prevent swelling and to minimise moisture transport. When CNS soils are not available, linings using geogrids are suggested. The cells of the grid can be filled with nonplastic granular materials, stabilised soil blocks, or thin concrete blocks. A bitumenised surface coating minimises moisture ingress whilst a sand wick drain beneath the grid allows drainage of the soil mass. Cost comparisons are presented.
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