The Loess Collapsibility And Its Evaluation Method

Relying on the projects of loess foundation treatment and ground test along the Zhengzhou-Xi'an Passenger Line, based on the indoor physical and mechanical properties of loess and Collapsibility test and immersion test at the scene, using qualitative analysis and quantitative analysis which is based on data mining technology, the loess collapsibility and its distribution characteristics and the law along the line has been studied, with the mechanism and the formation causes of loess collapsibility been discussed and the influencing factors of the collapsibility and the extent of its impact been analyzed, the nature of loess collapsibility has been explained, finally the Comprehensive Evaluation Method for the loess collapsibility under the multi-factor coupling is brought forward.Based on a large number of laboratory test data and field measurement data, the research on the collapsible loess along the Zhengzhou-Xi'an Passenger Line has been carried out as follows. (1) Through the study on the engineering geological environment along the line, taking the loess in eight test sites as the major study object, analyze the engineering geological conditions of each site, explain the distribution of loess and its engineering properties along the line. (2) According to laboratory test of collapsibility, study the change characteristics of the loess collapsibility in the space, which shows that the collapsibility Both in vertical direction or region is in line with the exiting laws. (3) Through the analysis of the material composition, physical and mechanical properties, microstructure, initial moisture content and state of stress in each sites, analyze various factors for the collapsibility by using engineering geological analogy method and Data Mining Technology, and has obtained the integrated relationship between the collapsibility coefficient and the indicators of the physical properties on behalf of various factors, which has showed that the loess collapsibility is the macroeconomic performance under a variety of factors, in which the material composition and micro-structure characteristics are Internal factors, but initial moisture content and state of stress is the external factor. (4) According to the site immersion test in a large area, analyze the self-weight collapsibility feature under the conditions of saturated water, study the regional distribution law of the collapsibility volume, with the trend of the self-weight collapsibility volume along the line is increasing from the east to the west and a "non-uniform jump-style" change characteristic. (5) Through the analysis and research, the collapsibility is determined commonly by the loess collapsibility, soil structure and the occurrence environment change, Comprehensive Evaluation Method under various factors has been brought forward, the relationship between the collapsibility volume and soil structure has been educed, the nature of the loess collapsibility has been interpreted, with a successful interpretation of the so-called "abnormal" phenomenon of the loess collapsibility. Loess collapsibility is the restructuring phenomenon of the original structure of the collapsible loess under adverse conditions of the occurrence environment, which has a specific material composition and structural characteristics; the collapsibility volume depends on the loess collapsibility of its own macro-structure characteristics and the extent of the occurrence environmental change.Through the research on the loess collapsibility evaluation, based on the nature of loess collapsibility, a reasonable selection of relevant factors of collapsibility and integrated and systematic evaluation method can provide a reference for other projects.