Numerical case study of a braced excavation

Numerical case study of a braced excavation

212A Earth retaining structures 894344 Diaphragm wall chamber system for hazardous waste isolation Arz. P Proc lnt Conference on Foundations and Tunn...

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212A

Earth retaining structures 894344 Diaphragm wall chamber system for hazardous waste isolation Arz. P Proc lnt Conference on Foundations and Tunnels, London, 2426 ~larch 1987 V2, P125-136. Publ Edinburgh. Engineering

Technics Press. 1987 Isolation of a waste tip has been achieved by the installation of a double skinned slurry cutoff wall, with an 8m spacing and cross-walls every 50-70m. Wells inside each chamber and in the enclosure prevent contamination from the tip reaching the natural groundwater. The cement-bentonite walls, using Ca bentonite, are more resistant to toxic wastes, have a higher solids content and are more difficult to process than conventional slurries. Construction by vibratory beam injection. advantages, and costs of the system are discussed. 894345 Input to finite element analysis of braced excavations Lin T S; Ou, C D: Deng, J G Proc Eighth Asian Regional Conference on Soil Mechanics and Foundation Engineering, Kyoto, 20-24 July 1987 VI,

P301-304. Puhl Japan: Japanese Society for Soil Mechanics and Foundation Eng#wering. 1987 Eight excavations in Taipei silt were studied in order to determine the suitability of the finite element method to predict behaviour of braced excavations, and to investigate connections between input properties of the soil and input parameters, which were determined by triaxial tests on soils at one site. Finite element analysis described observed deflections of the excavation walls satisfactorily, and in all but one case the assumed soil parameters proved consistent with observed behaviour. 894346 Watertightness of the diaphragm wall at vertical joints Ou, C D; Lee, K H

Proc Eighth Asian Regional Conference on Soil Mechan&s

894348 .Methods of improving the stability of deep excavations in soft clay Wong, K S; Wong, ! H; Broms, B B Proc Eighth Asian Regional Conference on Soil Mechanics and Foundation Engineering, Kyoto, 20-24 July 1987 VI,

P321-324. Publ Japan: Japanese Society for Soil Mechanics and Foundation Engineering. 1987 Deep excavations in soft clay are often accompanied by unacceptable settlement, lateral wall deflection, and heave of the bottom of the excavation. Finite element analysis has been used to assess the potential of three stabilisation methods. These are jet grouting of a zone of soft clay inside the sheet pile walls prior to excavation, use of piles driven below the bottom of the excavation to increase passive resistance at the toe of the sheet pile, and excavation under water, with dewatering after the basement slab is installed. Numerical analysis suggests all three methods will be effective. 894349 Behaviors of strut braced sheetpile wall in soft ground excavations Woo, S M; Moh, Z C; Song, T F Proc Eighth Asian Regional Conference on Soil Mechan&s

and Foundation Engineering, Kyoto, 20-24 July 1987 VI, P325-328. Publ Japan." Japanese Society for Soil Mechanics and Foun&ttion Engineering. 1987 Ground settlement and pile wall movement recorded at 4 sites are reported. Movements after initial excavation, after struts are included, and during construction of the basement and removal of the struts are described. Behaviour is related to site activity and is time dependent. Where a much stiffer diaphragm wall was also used at one site, associated lateral displaccment and settlement were much reduced. 894350 Construction failures of excavation in soft clay - case studies Kao, T C; Wang, C H; Moh, Z C Proc Eighth Asian Regional Conference on Soil Mechanics

P309-312. Publ Japan: Japanese Society Jor Soil Mechanics and Foundation Engineering. 1987

and Foundation Engineering, Kyoto, 20-24 July 1987 VI, P297-300. Publ Japan: Japanese Society for Soil Mechanics and Foundation Engineering, 1987

Diaphragm walls constructed in slurry trenches are assembled from cast panels. The watertightness of the wall is dependent on type and quality of the joint between panels. Laboratory tests on bentonite cake indicate that the presence of a thin layer of caked bentonite on the joint surfaces will not have deleterious effects. Joint watertighmess of a series of systems has been investigated in field tests. A modification to the overlapping joint is suggested to minimise water flow through the wall on deflection due to excavation.

Failures of two retaining structures, for a storm drain and a hotel basement in Taiwan, are described. In the first case excessive heave occurred, and in the second slope stability problems above the basement were encountered. Back analysis showed laboratory testing had seriously overestimated the remoulded strength of the clay, and marginal factors of safety were much lower than assumed. The problems of designing using semi-empirical methods developed under different geological conditions are discussed.

894347 Numerical case study of a braced excavation Tan, S B; Tan, S L: Chin, Y K Proe Eighth Asian Regional Conference on Soil Mechanics and Foundation Engineering, Kyoto, 20-24 July 1987 VI, P3-

894351 Prediction of the behaviour of earth retaining walls Konoike, K; Ono, K Proc Ninth Southeast Asian Geotechnical Conference,

and Foundation Engineering, Kyoto, 20-24 July 1987 VI,

16. Publ Japan: Japanese Society for Soil Mechanics and Foundation Engineering, 1987 Predictions of finite element analyses using one- and twodimensional elastoplastic models and field observations of ground movements associated with an excavation in very soft Singapore marine clay are compared. Lateral sheet pile deflections, strut loads, settlement profile.and earth pressure are in satisfactory agreement. Under conditions of marginal stability, overexcavation can result in large movements and high strut loads.

Bangkok, 7-II December 1987 VI, P2.13-2.22. Publ Bangkok: Southeast Asian Geotechnical Society A method to predict the behaviour of an earth retaining wall has been developed. The method calculates displacement and bending moment of the wall by framed structure analysis. Assumptions on rigidity of wall resistance of supporting ground, and load are discussed. Spring constant and load intensity are determined at each excavation level. The method is applied to a steel sheet pile wall and a reinforced concrete wall, and results show good agreement with field measurements.

~j 1989 Pergamon Press pie. Reproduction not permitted