Study On Frost Heave Problem Of Loess Foundation With Load

The problem of frost heave in loess areas has caused various forms of diseases for the project,such as foundation tilt,uneven uplift,freeze-pile problems of pile foundations,etc.With the development of our country's economy,there are more and more problems with high-load frost heaving,such as shallow-buried pile foundation engineering in the permafrost region,soil between piles in shallow buried composite foundations,temporary storage tanks in frozen soil areas,and loess frozen walls and the tunnel section of the loess.At present,there is still lack of evaluation methods for the problem of frost heaving of loess with high loads.It is necessary to consider the load to study the frost heave problem of loess.Frost heave coefficient is an important parameter to evaluate the frost heaving of loess.This paper studies the frost heave coefficient and application of loess.First,the remodeling loess freezing experiment was carried out considering the moisture content,dry density and load effect.The test device was modified to achieve a maximum load of 500 kPa.According to the test results,the influences of water content,dry density and load on the frost heave coefficient of remolded loess were analyzed.The moisture content and dry density had a strong linear positive correlation with the frost heave coefficient;under high load conditions,the moisture content is more sensitive effecting on the frost heave coefficient;regardless of the soil conditions,the load and the remolding frost heave coefficient of the loess have a negative exponential relationship.Secondly,according to the results of laboratory experiments,the formula of frost heaving coefficient of loess considering loads is proposed,and the significance of the parameters in the formula and the solution methods are given.The test results and the formula of frost heaving coefficient are compared and analyzed to verify the rationality of the formula and proven applicability.Finally,the maximum thickness of permafrost allowed to be studied using this formula.The shortcomings and deficiencies of the standard method for determining this thickness were analyzed;Based on the principle that the frost heave of the foundation design index did not exceed the maximum allowable frost heave,a method considering the effects of high loads,heating conditions and basic forms has been proposed.The method for calculating the maximum thickness of permafrost shows that the applicable range of the load of this method is greatly improved compared with the specification.In this paper,the effect of load on the frost heave coefficient of remolded loess is obtained through laboratory tests,and a formula for frost heave coefficient is proposed.Based on this formula,a new calculation method for the maximum allowable permafrost layer thickness is proposed,and the high load and intense frozen soil are extended by this method.Research results can be used for loess engineering design.