CONSTRUCTING STRUCTURE FOR PREVENTING THRUSTING FLOTATION AND FROST HEAVE OF MANHOLE AND SETTLEMENT, CRACK, WAVINESS AND FROST HEAVE OF BACKFILL SOIL ON MAIN PIPE DUE TO EARTHQUAKE OR THE LIKE

摘要

PROBLEM TO BE SOLVED: To prevent the liquefaction of backfill soil due to earthquake or the like, the thrusting floatation and frost heave of a manhole due to freezing expansion, and the crack, waviness and settlement of backfill soil on a main pipe.;SOLUTION: In backfill construction of placing a sewage line including the manhole and the main pipe, a liquefaction preventing material formed by mixing a water non-permeable and non-oozing asphalt raw material and an elastic body (a rubber chip) is poured into a drive gap between the manhole and a natural ground and filled therein for backfill. Otherwise, the liquefaction preventing material and gravel or crushed stones are alternately bedded into a plurality of layers for backfill in the condition of embracing the liquefaction preventing material to prevent the flotation and oozing of underground water. This prevents the flotation and frost heave of the manhole resulting from the liquefaction of a backfill portion due to earthquake and from the freezing expansion thereof and prevents the settlement, waviness, crack and frost heave of the backfill soil on the main pipe.;COPYRIGHT: (C)2006,JPO&NCIPI