Correlation between floor deformation and environmental factors in SACLA accelerator building

The floor of SACLA accelerator and undulator building were monitored by many HLS(Hydrostatic Leveling System), WPS(Wire Positioning System), electrolytic tilt sensor, crack sensor, extension sensor, and Pt100 sensor. The floor level does not affected by the atmospheric pressure in the area where undulators are located. However in the upper-stream the floor level sinks, which maximum rate 0.3 μm/hPa. The linearity in the north-south horizontal direction shifts seasonally 50 μm between 110 m length. There is also 20 μm/year drift. The elevation change is large at the boundary area between accelerator tunnel and undulator hall. The amplitude is 0.7mm in a year. The extension is also large at this area. The largest coefficient of level vs atmospheric pressure is 1.5 μm/hPa in the accelerator area where the filled depth is largest. These sinking rate is similar to the elasticity coefficient and useful for the estimation and comparison of the improved ground. (author)