Improvement of the integrity and seismic resistance of gravity sewers

Summary

The problems of improving the integrity and seismic resistance of wastewater disposal systems have been urgent and must be solved in the process of designing prospective plans of territorial and urban development as well as investment programs of public utilities. The procedure of wastewater system structure optimization based on developing redundant layout and searching the maximum flow of the minimum weight function (minimum cost, maximum integrity and seismic resistance) is suggested. Redundant layout is developed by overlapping the predesigned sewer routes. The integrity is evaluated by the quantitative index – raw sewage amount that is generated for the certain time period as a result of an accident and pipeline rehabilitation time. Seismic resistance is taken into consideration by increasing failure rate depending on the earthquake intensity and orientation of the seismic impact. The suggested procedure takes into account seismic impacts by increasing the length of the designed sections of the redundant sewer layout. It is shown that construction of subsidiary and loop sewers improves significantly the integrity and seismic resistance of sewers.

Key words

water disposal system , seismic forces , optimization method , redundant layout , quantitative index of integrity , seismic resistance