Underground Singapore 2011 Reservoir 壁（ｔ＝2,000mm） Wall (t=2,000mm)
壁（ｔ＝4,000mm） Wall (t=4,000mm)
20
15
140 60
15
20
Connecting pipe
20
15
60 140
15
20
Super high rise building Sunshine court
67.5m
LE ▽GL B1F
Underground building
Lowered water level by continuous pumping
B21F
Mat slab 耐圧版
5 5 22.5m
B15F
Wall: 4 floors, h=18.5m 壁（4層分：ｈ＝18.5ｍ）
Figure 9 Wall system to deal with floating force.
Water tank Connecting pipe
Machine room Mat slab
Reservoir
Figure 10 The idea to draw out water.
Instead of dealing with structural system to transmit vertical loads, the method to draw the water out from under the bottom of basement to reduce the floating force is studied. The evaluation of the volume of seepage water needs the evaluation of the coefficient of permeability. Since the data to evaluate permeability is not enough, three cases of the coefficients were used in the study (Miyake et al. September 2000, Tomizawa et al). There are two different methods, gravity well method and artesian well method, which corresponds to shallow well and deep well respectively, to estimate seepage water and evaluated volumes for these two methods are compared in Table 4. There are large differences among the results by two methods, but observation more coincides with the results by artesian well method. Extensive discussions still need to be carried out if the measure to draw out the water is applicable in practice since the drawn water could be called as “waste” depending on the volume and might not be permitted to be flowed out. One idea of drawing water method is illustrated in Figure 10. 4.4 Structural control system to reduce earthquake load Time history analyses subjected to earthquake excitation are carried out for the super high rise building model and for the conventional super high rise building model built on ground surface as the comparison. Analytical model for these two buildings are shown in Figure 11. Building is modeled in 57 lumped masses for section above ground and 13 masses for the section of underground level. Hydraulic dampers are modeled as dashpots which connect 13th mass with ground surface. Nonlinear characteristics are considered for the stiffness of the structures. Earthquake excitation at engineering bedrock is used for the proposed building and earthquake at ground surface is used for conventional building built on ground surface.
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