Study On Engineering Characteristics And Curing Measures Of Collapsible Loess Which Xi'an Metro Project Pass Through

Collapsibility is a typical engineering geological problems in loess region,and always do harm to the construction activities.Indoor calculated value of loess collapsibility is often quite different with the measured value,so it is necessary to do more works in the collapsibility of the loess.This paper takes the collapsible loess which the fourth Xi'an subway pass through as the research object,based on field trials and laboratory test results,in-depth study of loess collapsibility deformation characteristics by numerical analysis to explore the reason of the difference between the calculated value and the measured value in the collapsible sink,to get the following conclusions:(1)indoor and outdoor collapsible stress test path differences,differences in the test environment,immersion saturation difference that makes the difference between the two results;(2)collapsible soil units are not Loess continuous distribution due to redistribution of stress after immersion in water,making the wet soil unit of collapsible trap potential not full,resulting Found collapsible amount is smaller than the calculated value of the specification,in collapsible soil unit distribution is disordered,collapsible soils when the stronger this effect is more obvious.Through summarizes 13 group test pits water immersion test data on since 2004 undertaken,Xi'an subway through the loess response was studied,achieve the following results:(1)established considering loess deposits age and the Collapsible soil is not continuous distribution dead-weight effect trapping amount calculated empirical formula;(2)a new method of Xi'an Metro collapsible loess foundation engineering evaluation,which proposesadvanced exploration stage loess collapsible specification method can be used to calculate the amount of empirical formula and evaluated,detailed prospecting stage field test pit water immersion test;(3)the development of the subway project collapsible Loess tunnel foundation principles: non-collapsible subway tunnels Loess site across all types of construction method is formed can't be taken for collapsible appropriate measures loess foundation treatment;subway tunnels weight within loess site through various types of construction method can be formed by fuzzy comprehensive evaluation method to establish the relationship between various indicators of evaluation,the evaluation given grade,take the appropriate principles for different levels;(4)according to the foundation through the subway tunnel project collapsible established principles,combining the characteristics of subway project,given the metro project through the loess foundation treatment measures recommended.Results of this study for the design and foundation treatment subsequent Xi'an subway project structure provide reference and guidance,and provide technical support for Xi'an subway construction under similar geological conditions.