Seite - 1235 - in Book of Full Papers - Symposium Hydro Engineering

2. MONITORING SYSTEM CONFIGURATION Figure 1 shows the arrangement the monitoring system. The suggested secant-pile wall consisted of reinforced concrete piles with a diameter of 60 cm spaced at 90 cm from center to center intersected with bentonite piles with a diameter of 60 cm and the over lapping distance is not less than 15 cm. The reinforced concrete pile penetrated the upper fill layer and the soft clay layer and extended in the lower sand layer to about 50 cm with a total length equal to 16.50 m. The bentonite piles extended to 6 m in the soft clay layer with a total length approximately equal to 10 m. Fig. 1: The arrangements of the monitoring system The monitored reinforced concrete piles in the wall were named P52 and P54 and the monitored bentonite pile was named P53. Pile P52 was instrumented with vibrating wire strain gages (s.g) on the reinforcing steel bars at levels of -1.80 m, -5.50 m, and –11.00 m relative to the zero sea level. Pile P54 was instrumented with vibrating wire strain gages at levels of -1.80 m, -4.50 m, - 7.80 m, -10.80 m, and -13.80 m. In addition to the strain gages, P54 was provided with inclinometer casings and magnetic rings of sondex system at levels of -0.90 m, -3.93 m, -6.94 m, -9.95 m, and -12.96 m. Pile P53 (the bentonite pile) was instrumented with an inclinometer casing and magnetic rings of sondex system at levels of -0.93 m, -2.93 m, and -5.97 m. In addition to the instrumented piles, three piezometers were installed to monitor the variation of water level. Piezometer (1) was installed at the centerline of the road, piezometer (2) was installed adjacent to the secant wall in the roadside, and piezometer (3) was 1235