The practice of building and operating of railroad beds shows that the greatest attenuation of soils occurs in the spring, during their Iransifion from the frozen to thawed state. The geatest influences on the propert...The practice of building and operating of railroad beds shows that the greatest attenuation of soils occurs in the spring, during their Iransifion from the frozen to thawed state. The geatest influences on the properties of clay soils that form the railway are from hydration, fieeze-thaw cycles and vibrodynamic impact of Wains. The increase in soil moisture is due to infillration of water into the ground, as well as the rise in water level due to soil redistribution during winter freezes. This can dramatically alter the basic characteristics of the soil, such as shear resistance and bulk density, on which strength and stability of soil mass depend primarily. Therefore, the degree of railway bed stability is not constant, but varies with time.展开更多
The permafrost table is an important index for the design and construction of roads in cold regions,so it is necessary to find a convenient,accurate and fast judgment method to determine the permafrost table.In this s...The permafrost table is an important index for the design and construction of roads in cold regions,so it is necessary to find a convenient,accurate and fast judgment method to determine the permafrost table.In this study,a three-field coupled model was established based on the hydrothermal salt coupling within the permafrost and the similarity theory,and the changes of the permafrost table under different temperature,moisture and salt conditions were numerically simulated by considering the transient temperature change and the influence of the permafrost layer on the seasonally thawed layer.In addition,an accelerated permafrost table test method was designed based on the time-domain variation and hydrothermal salt coupling by the similarity theory,which rapidly simulated the permafrost table change under different temperatures,moisture,and salts in the natural environment.Comparing the simulation and test results with the measured values in the field,the errors are less than 3%,which verified the feasibility of the method for determining the permafrost table,and the simulated results are better than the test results.Results show that the results of determining the permafrost table with a single index have different degrees of deviation,and the permafrost table obtained by the temperature index is the most accurate in general,and it is more accurate to use the average value of the three indexes as the permafrost table compared with a single index.展开更多
文摘The practice of building and operating of railroad beds shows that the greatest attenuation of soils occurs in the spring, during their Iransifion from the frozen to thawed state. The geatest influences on the properties of clay soils that form the railway are from hydration, fieeze-thaw cycles and vibrodynamic impact of Wains. The increase in soil moisture is due to infillration of water into the ground, as well as the rise in water level due to soil redistribution during winter freezes. This can dramatically alter the basic characteristics of the soil, such as shear resistance and bulk density, on which strength and stability of soil mass depend primarily. Therefore, the degree of railway bed stability is not constant, but varies with time.
基金the National Natural Science Foundation of China(Grant Nos.52078177and 51408005)Anhui Jianzhu University scientific research project(HYB20210134)Anhui Provincial Natural Science Foundation(2308085ME187)。
文摘The permafrost table is an important index for the design and construction of roads in cold regions,so it is necessary to find a convenient,accurate and fast judgment method to determine the permafrost table.In this study,a three-field coupled model was established based on the hydrothermal salt coupling within the permafrost and the similarity theory,and the changes of the permafrost table under different temperature,moisture and salt conditions were numerically simulated by considering the transient temperature change and the influence of the permafrost layer on the seasonally thawed layer.In addition,an accelerated permafrost table test method was designed based on the time-domain variation and hydrothermal salt coupling by the similarity theory,which rapidly simulated the permafrost table change under different temperatures,moisture,and salts in the natural environment.Comparing the simulation and test results with the measured values in the field,the errors are less than 3%,which verified the feasibility of the method for determining the permafrost table,and the simulated results are better than the test results.Results show that the results of determining the permafrost table with a single index have different degrees of deviation,and the permafrost table obtained by the temperature index is the most accurate in general,and it is more accurate to use the average value of the three indexes as the permafrost table compared with a single index.
