PURPOSE: To eliminate necessity for work of centering adjustment by placing mortar at the bottom of a pit before installing a barrel casing and by setting an anti-quake support fixed to the lower part of the barrel casing in this mortar together with the barrel casing.

CONSTITUTION: An arm-shaped pipe 7 is welded to the bottom of a barrel casing 3 to be fitted in a support 8 with separability, and therewith an anti-quake supporting mechanism is constituted. First, as shown in Fig. (a), mortar 9 is placed in the pit 1 and then the anti-quake support including barrel casing 3 is set in the pit 1, as shown in Fig. (b), before the mortar hardens. An appropriate adjustment of the amount of mortar 9 can bring about a condition that no mortar 9 intrudes into the fit part of the anti-quake support, which assures out of inconvenience even at the time of disassembly. According to this arrangement, no centering adjustment is required for installing the anti-quake support and, further, this small gap in supporting assures effective anti-quake support.