Page - 885 - in Book of Full Papers - Symposium Hydro Engineering

2. DAM CREST SETTLEMENT AND LEAKAGE PROBLEM The differential settlement between the RCC spillway and the earth dam is occurred causing the cracks and gaps at the RCC blocks. In the first filling, the water overtopped the spillway and flow through the cracks and gaps. The leakage was observed at the downstream crest near the contact area between the RCC part and the earth zone part as shown in Figure 4. They are repaired by the impervious membrane covering at the upstream surface of RCC blocks, the leakage is reducing but stilling. The downstream population worried about the safety of the Mae Suai dam especially in case of earthquake. Fig. 4 Leakage occurred near the joint between RCC and earth fill, the differential settlement is clearly seen 3. CHIANG RAI EARTHQUAKE AND RESPONSE OF DAM Fears of an earthquake have deepened after 6.3 magnitude earthquake hit the province in May of 2014. The epicenter to the dam site is 18 km. However, the epicenter of the aftershock is closer to the dam site. Mae Suai Dam is located in the active faults zone as shown in Figure 5. The dam experienced the strong ground motion and the accelerometer at the right abutment recorded the maximum PGA of 0.33g. Fortunately, the seismic force did not affect the Mae Suai Dam. The dam performed well. There is some crack observed in the concrete cover of the RCC block on the crest of the dam. The crack is much 885