The Study In Unconfined Compression Tests Under Dynamic Load Of Sandy Soil In 109th National Highway

ABSTRACT:Frost heaving and frost boiling are common diseases of roadbed in seasonal frost area. They destroy the work states of roadbed seriously and restrict the development of traffic which have become the seriously problems plaguing the construction of road in our country. In recent years, as the work time spending of the new roads and the frost and thawing cycle times increasing, these problems became much more serious. Therefore, it would be very important and meaningful to study on the mechanism, influence factors and development laws of those frost damages. The study of this article is one part of the western development of transportation technology projects "the mechanism and prevention of frost heaving and frost boiling in western region under dynamic load". The soil of State Road 109 which is heavily damaged in Qinghai Province has been selected as the object of study, and series of work was done, including the field investigation, unconfined compression test of thawing sandy silt under cyclic loading. Based on the test results, the laws of frost heaving and frost boiling are analyzed as well as the mechanism and its influence factors, and at the same time the propose practical engineering measures controlling the damage of roadbed are summarized. The main achievements include the following parts:1,This paper summarizes the achievement and present study situation in frozen soil as well as frost heaving and frost boiling, which is very important to the research in theoretical way.2,Based on the engineering investigations and soil physical index analysis of the Xiangpishan part of State Road 109, it was found that the classification of soil, water contents, temperature and outside loading are confirmed to be the main factors which affect the frost damages.3,The experiment of the soils in seasonal and perennial frost area in open system indicates that, different freezing temperatures have greatly effects on freezing time, freezing height, frost heave rate, and the amount of frost heave.4,From the unconfined compression tests of thawing sandy silt under cyclic loading, we can conclude that dynamic loading has little effect on the temperature field and other factors, but the freezing temperature and melting temperature in the roof would affect the external load, the temperature field and the deformation of the samples significantly. 5,After analyzing the freezing and thawing factors in experiment, some effective measures to control the damage in seasonal froze area are proposed in this article which are very important to the road construction in that area.