Centrifuge Model Tests on Settlement Controlling of Piled Raft Composite Foundation in High Speed Railway

摘要

The settlement after construction of subgrade is a crucial issue on the design of high speed railway. Based on the experimental study in China and abroad, the centrifuge test is used to imitate piled raft composite foundation in different pile spacing, to investigate and analyze the settlement controlling ability of piled raft composite foundation in collapsible loess ground in high speed railway. Then the relationship among piles, gravel cushion, soil and raft structure controlling the settlement are concluded by analyzing the test data. The research results show that untreated ground which can not meet the requirement on settlement after construction in ballasted track for high speed railway need be reinforced. The total settlement, settlement after construction and settlement ratio of piled raft composite foundation get larger with increasing pile spacing. The settlement of soil is also faster than the settlement of pile, and pile-soil load share ratio becomes lower while negative skin friction of pile increases.