Method for measuring load threshold value of soil deformation state of railroad bed under static load

Abstract

The invention relates to a method for measuring a load threshold value of a soil deformation state of a railroad bed under a static load. The method is characterized by comprising the following operating steps: building a filling model in a model case formed by rigid side walls and applying static loads in grade to the filling model by using a round rigid loading plate according to different proportionality coefficient lambda of the ultimate bearing capacity; measuring and calculating plastic deformation rates vi(t) of soil at different moments t in a loading process by using a displacement sensor, taking data points of the rates and fitting the data points according to a negative power function v(t)=At-alpha; and obtaining a power exponent alphai value corresponding to the load proportionality coefficient lambda, and fitting the power exponent alphai value to obtain an alpha-lambda curve according to a cubic polynomial, wherein taking loads piI=lambdaIsigmaf and piII=lambdaIIsigmaf corresponding to lambdaI and lambdaII of two curature maximum values of the alpha-lambda curve are adopted as the load threshold value of the soil deformation state. piI and piII can be used for providing test grounds for design and optimization of ballastless / ballast track beds of a high speed railway and a deformation state evaluation and regulation principal, respectively. The method has the characteristics of being relatively short in testing time and specific in criterion, and the obtained load threshold value is relatively accurate and reliable.

Description

technical field [0001] The invention relates to a method for measuring the load threshold value of the deformation state of railway foundation soil, and belongs to the technical field of soil engineering. Background technique [0002] The post-construction settlement of the railway subgrade will seriously affect the geometric smoothness of the track structure, and then affect the smoothness and safety of driving. The main reason for the subsidence of the railway subgrade is that the foundation is deformed by the long-term action of the self-weight of the superstructure such as the embankment. For ballasted track railways, in the long-term operation process, the smoothness of the track structure can be maintained by maintenance methods such as lifting, ballasting, and vibration. Therefore, certain deformation of the foundation is allowed. However, in order to ensure the efficient operation of the railway and the effective utilization of the line, the foundation of the ballas...

AI Technical Summary

Problems solved by technology

There are the following deficiencies: 1) Due to the limitation of the small size of creep geotechnical test specimens and the accuracy of sensor testing, it is difficult to obtain 10 -6 ~10 -4 Mechanical response data under micro-strain conditions; 2) Determining the load thresholds of the two deformation states of slow stability and slow failure of the soil lacks a clear and quantitative criterion, which is largely arbitrary and subjective, and the threshold fluctuation range is too large; 3) The creep test process takes too long to be widely used in large-scale engineering construction

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