Ground movements associated with twin-tunnel construction in clay

摘要: The rising population in urban environments comes with an associated demand for increased public transport. Due to the level of surface congestion often utilised solution is construct rapid transit systems within tunnels. Any sub-surface construction will generate ground movements which have potential cause damage existing and structures. Urbanisation congested cities driven need accurate predictions tunnelling-induced settlements has produced many publications (e.g. Peck, 1969; Cording & Hansmire, 1975; Clough Schmidt, 1981; O’Reilly New, 1982; Attewell Yates, 1984; Cording, 1991; Mair et al., 1993 Taylor, 1997). Largely, however, these empirically based prediction methods are concerned single tunnel greenfield, arrangements. Generally, mass transport comprise a pair tunnels constructed relative close proximity. This known as twin-tunnel construction. A number case studies shown difference due each Cooper 2002; 1975 Nyren, 1998). These were further investigated by numerical support observations Addenbrooke Potts, 2001 Hunt, 2005). Analyses that use isotropic linear elasticperfectly plastic soil models tended produce wider settlement troughs then observed Gaussian distribution (Mair 1981). It clear valuable insight could be gained from physical model study. Therefore, series plane strain centrifuge tests was carried out investigating twin overconsolidated clay. Apparatus necessary perform tasks required significant amount time develop relatively complex. main variables spacing between tunnels, both horizontally vertically, magnitude volume loss. conducted at 100g where cavities represented two 4m diameter (usually) depth 10m prototype scale. novel apparatus designed during research enable simulation processes related loss separate sequential tunnels. The results presented regards perpendicular advancing findings follows: - 1. Single well distributions, twin-tunnelling can improved modifying solely second construction. 2. new had presence first tunnel. effect lessened larger spacings tunnels. 3. Second predicted using equations Peck (1969), New (1982) al. (1993) but modifications. distributions towards than