3.4　Seismic Precaution

3.4.1　Evaluation of seismic safety shall be made for the site proposed to construct large tank farm.

3.4.2　Seismic precautionary category of the foundation for tank in volume larger than 50000m3 shall be classified into CategoryⅡ，and Seismic precautionary category of foundation for tank in volume equal to or less than 50000m3 shall be classified into CategoryⅢ.

3.4.3　Liquefaction judgment of saturated sand and saturated silt and their subgrade treatment shall comply with the following requirements:

1　For seismic precautionary intensity 6，when the volume of tank is smaller than or equal to 50000m3，liquefaction judgment and subgrade treatment may not be required，when the tank in volume larger than 50000m3，liquefaction judgment and subgrade treatment shall be done on a basis of seismic precautionary intensity 7.

2　For seismic precautionary intensity 7 and 8，liquefaction judgment and subgrade treatment shall be made，and liquefaction resistant measures shall be taken based on the seismic precautionary category of the tank foundation and the liquefaction grade of the subgrade.

3.4.4　Earthquake action on tank foundation shall be determined in accordance with the current national standard Code for Seismic Design of Special Structures（GB 50191）.