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Dam foundations on rock masses - the Alto Lindoso dam example
379A
Ground freezing 926308 Interconnecting tunnel for the Ameria pumping station of the Greater Cairo Wastewater Project Wassif, A A Tunnlg Underground Space Technol V7, N2, April 1992,
P145-148 Construction of a 5m internal diameter tunnel through saturated sand to connect the caisson-constructed pumping station and distribution chamber is described. Ground treatment from the surface was difficult and ground freezing with freeze pipes from inside the distribution chamber was used. Localised failure of the ice wall (reason unknown) led to flow of sand and water into the structures. To stabilise the condition, it was necessary to flood the caissons to balance inside and outside water pressures. A supplementary vertical freeze system was used to reinstate the frozen ground, the caissons pumped dry, and tunnel work resumed.
926311 Dam foundations on rock masses - the Alto Lindoso dam example Marques, R Proc International Conference on Mechanics of Jointed and Faulted Rock, Vienna, 18-20 April 1990 P891-897. Publ
Rotterdam: A A Balkema, 1990 The Alto Lindoso dam on the river Lima in Portugal is founded on mica-shist with igneous inclusions and faults, some of which contain clay filling. The construction was based on extrapolation of site characterisation data from the initial chosen site, some 650m downstream. Stability problems were found for slopes downstream of the abutment. It is shown how this could have been avoided if more detailed investigation of the actual site had been carried out, using, for example, zoning, classification, or the Markland test.
Base courses and pavements
Surface Structures Geological factors of importance in surface structures 926309 Thirteenth Bjerrum Memorial Lecture: a case history of mysterious settlements in a building Duncan, J M Can 6eotech J V29, N1, Feb 1992, PI-IO One Lombard Building, San Francisco, is founded on 3-5m of made ground over 10m of Bay Mud, then sands. Large and damaging settlements began when construction of a sewer started nearby, although it was not initially possible to connect the two. Underpinning was used to stabilise the building. The search for the cause of settlement continued, and it was finally attributed to consolidation on thaw of frozen mud beneath the structure as a result of the sewer construction. The frozen soil was a relic of days when the basement was a frozen food store.
926310 Building a residential complex on a slow deep-seated slope instability Oboni, F; Hlobil, Z Proc Conference on Slope Stability Engineering:
Developments and Applications, Isle of Wight, 15-18 April 1991 Pl13-117. Publ London." Thomas Telford, 1991 The case of a proposed development in Switzerland on a slope affected by a deep seated, slow (velocity less than 10 mm/yr) slide is discussed. Geotechnical characteristics of the sliding mass and its movement pattern were first established. Stability analysis under proposed loading conditions was performed using a probabilistic model. Design criteria to reduce hazards during construction and in use were investigated. Special works were required for foundations and retaining structures. Jet grouting was chosen on grounds of cost and effectiveness for both applications.
926312 Violation of Westergaard's full contact assumption and its effect on raft unit pavements. Technical note Bull, J W
Comput Geotech V12, N2, 1991, P133-157 Concrete raft units on sand bedding and subgrade are widely used in pavement construction. Design is generally based on the assumption that full contact is maintained at all times. Changes due to surface and support layer displacements and stresses if this condition is violated are investigated using three dimensional finite element analysis. If lift-off from the subgrade is allowed, stresses and displacements increase and pavement life is reduced. The subgrade has greater effect than assumed on pavement surface displacements. Increased stiffness of the bedding and subbase will decrease these displacements.
926313 Mechanistic pavement design using a Pencei Pressuremeter (PSPP) Sanders, P J Proc Tenth Regional Conference for Africa on Soil Mechanics
and Foundation Engineering and the Third International Conference on Tropical and Residual Soils, Maseru, 23-27 September 1991 111, P177-183. Publ Rotterdam: A A Balkema, 1991 The use of the Pencel Shear Pavement Pressuremeter to obtain elastic moduli for pavement design is described. The instrument, developed from an existing pavement pressuremeter and a borehole shear tester, gives elastic moduli within 10% of those from a Heavy Vehicle Simulator (HVS), the basis of many mechanistic design procedures in South Africa. The costs of using incorrect values of subgrade modulus are assessed. Comparison is made between PSPP and HVS values at one site. These data are used to illustrate a method for predicting elastic moduli under traffic loading, based on multilayer linear elastic analysis.
© 1992 Pergamon Press Ltd. Reproduction not permitted
Ground freezing 926308 Interconnecting tunnel for the Ameria pumping station of the Greater Cairo Wastewater Project Wassif, A A Tunnlg Underground Space Technol V7, N2, April 1992,
P145-148 Construction of a 5m internal diameter tunnel through saturated sand to connect the caisson-constructed pumping station and distribution chamber is described. Ground treatment from the surface was difficult and ground freezing with freeze pipes from inside the distribution chamber was used. Localised failure of the ice wall (reason unknown) led to flow of sand and water into the structures. To stabilise the condition, it was necessary to flood the caissons to balance inside and outside water pressures. A supplementary vertical freeze system was used to reinstate the frozen ground, the caissons pumped dry, and tunnel work resumed.
926311 Dam foundations on rock masses - the Alto Lindoso dam example Marques, R Proc International Conference on Mechanics of Jointed and Faulted Rock, Vienna, 18-20 April 1990 P891-897. Publ
Rotterdam: A A Balkema, 1990 The Alto Lindoso dam on the river Lima in Portugal is founded on mica-shist with igneous inclusions and faults, some of which contain clay filling. The construction was based on extrapolation of site characterisation data from the initial chosen site, some 650m downstream. Stability problems were found for slopes downstream of the abutment. It is shown how this could have been avoided if more detailed investigation of the actual site had been carried out, using, for example, zoning, classification, or the Markland test.
Base courses and pavements
Surface Structures Geological factors of importance in surface structures 926309 Thirteenth Bjerrum Memorial Lecture: a case history of mysterious settlements in a building Duncan, J M Can 6eotech J V29, N1, Feb 1992, PI-IO One Lombard Building, San Francisco, is founded on 3-5m of made ground over 10m of Bay Mud, then sands. Large and damaging settlements began when construction of a sewer started nearby, although it was not initially possible to connect the two. Underpinning was used to stabilise the building. The search for the cause of settlement continued, and it was finally attributed to consolidation on thaw of frozen mud beneath the structure as a result of the sewer construction. The frozen soil was a relic of days when the basement was a frozen food store.
926310 Building a residential complex on a slow deep-seated slope instability Oboni, F; Hlobil, Z Proc Conference on Slope Stability Engineering:
Developments and Applications, Isle of Wight, 15-18 April 1991 Pl13-117. Publ London." Thomas Telford, 1991 The case of a proposed development in Switzerland on a slope affected by a deep seated, slow (velocity less than 10 mm/yr) slide is discussed. Geotechnical characteristics of the sliding mass and its movement pattern were first established. Stability analysis under proposed loading conditions was performed using a probabilistic model. Design criteria to reduce hazards during construction and in use were investigated. Special works were required for foundations and retaining structures. Jet grouting was chosen on grounds of cost and effectiveness for both applications.
926312 Violation of Westergaard's full contact assumption and its effect on raft unit pavements. Technical note Bull, J W
Comput Geotech V12, N2, 1991, P133-157 Concrete raft units on sand bedding and subgrade are widely used in pavement construction. Design is generally based on the assumption that full contact is maintained at all times. Changes due to surface and support layer displacements and stresses if this condition is violated are investigated using three dimensional finite element analysis. If lift-off from the subgrade is allowed, stresses and displacements increase and pavement life is reduced. The subgrade has greater effect than assumed on pavement surface displacements. Increased stiffness of the bedding and subbase will decrease these displacements.
926313 Mechanistic pavement design using a Pencei Pressuremeter (PSPP) Sanders, P J Proc Tenth Regional Conference for Africa on Soil Mechanics
and Foundation Engineering and the Third International Conference on Tropical and Residual Soils, Maseru, 23-27 September 1991 111, P177-183. Publ Rotterdam: A A Balkema, 1991 The use of the Pencel Shear Pavement Pressuremeter to obtain elastic moduli for pavement design is described. The instrument, developed from an existing pavement pressuremeter and a borehole shear tester, gives elastic moduli within 10% of those from a Heavy Vehicle Simulator (HVS), the basis of many mechanistic design procedures in South Africa. The costs of using incorrect values of subgrade modulus are assessed. Comparison is made between PSPP and HVS values at one site. These data are used to illustrate a method for predicting elastic moduli under traffic loading, based on multilayer linear elastic analysis.
© 1992 Pergamon Press Ltd. Reproduction not permitted