Method for measuring load threshold of geotechnical packing accumulated deformation state under cyclic loading

Abstract

The invention relates to a method for measuring load thresholds of geotechnical packing accumulated deformation states under cyclic loading. According to the method, brick walls and sand bags are adopted to construct a filling model, so as to form a testing system along with loading equipment and a displacement sensor, and a cyclic loading test is performed on the filling model, so as to obtain a changing curve of accumulated deformation with loading times; then the changing curve of segmented single loading average deformation with the loading times is obtained through calculation, and a negative power function as shown in the specification is adopted to fit, so as to obtain a relation curve of a power exponent Pi value with the change of load levels; a function relation between the Pi value and the load levels is obtained by virtue of cubic polynomial regression, and the corresponding load levels when P is equal to 2, 1 and 0 are obtained through back calculation, so as to be used as the load thresholds delta t1, delta t2 and delta t3 for distinguishing different evolution states of the accumulated deformation, wherein an experimental basis is respectively provided for design and maintenance of ballastless and ballast track bed structures of railways by the delta t1 and delta t2. The method has the advantages of convenience in model manufacturing, low cost, simplicity in operation and clear distinguishing criterion, and the obtained load thresholds are accurate and reliable.

Description

technical field [0001] The invention relates to a method for measuring the load threshold value of the accumulative deformation state of geotechnical filler under cyclic load, and belongs to the technical field of geotechnical tests. Background technique [0002] The upper part of the railway subgrade structure, that is, the subgrade part, bears the cyclic effect of the train load for a long time, and the accumulated deformation will seriously affect the smoothness of the track structure, and then affect the speed and safety of the train. Therefore, the cumulative deformation of the bed must be limited. my country's current regulations require that the total post-construction settlement of the ballastless track subgrade is not greater than 15mm, which is mainly considered for the post-construction settlement of the foundation below the subgrade structure, that is, it is required that the subgrade bed structure cannot undergo obvious cumulative deformation. For the ballasted...

AI Technical Summary

Problems solved by technology

There are the following deficiencies: (1) Due to the relatively expensive price of the dynamic triaxial test equipment, especially the large dynamic triaxial test used to carry out coarse-grained geotechnical filler tests, most geotechnical laboratories and research institutes are not equipped

In addition, the test operation is relatively cumbersome, and the professional quality of the test personnel is high, so it is difficult to popularize it in engineering design on a large scale; -4 ~10 -6 Mechanical response data under small strain conditions; (3) The load threshold for determining the cumulative deformation evolution state lacks a clear criterion, which leads to greater randomness and subjectivity in the analysis of test results

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