A method and test device for determining relative density sample preparation standard for indoor scale test of coarse aggregate

Abstract

The invention relates to a method and a test device for determining relative density sample preparation standards for indoor scale-down tests of coarse aggregates, belonging to the technical field of geotechnical testing. Firstly, the graded coarse aggregates are selected, and the maximum dry density value of the field test is obtained through the extreme value dry density test of the heavy-duty vibrating mill; the compaction parameters of the test device are adjusted through the compaction method of the surface vibrator, and different compaction methods, Maximum dry density value under compaction parameters. Then determine the equivalent compaction parameters under the selected indoor compaction mode as the compaction standard for the indoor maximum dry density test. Finally, according to the compaction standard, the indoor relative density test of the scaled material is carried out to obtain the extreme dry density of the scaled material; according to the design index, the dry density or porosity of the sample prepared for the indoor scaled test of the coarse-grained material is calculated and determined. The invention aims at the scale reduction problem of the original gradation coarse grain material, can reduce the influence of the scale effect of the coarse grain material, and effectively improves the precision of the indoor test of the coarse grain material.

Description

technical field [0001] The invention relates to an indoor scale test sample preparation standard widely used in water conservancy and civil engineering coarse grain materials, and belongs to the technical field of geotechnical testing. Background technique [0002] With the emergence of heavy-duty vibrating mills, the gradation range of engineering coarse-grained materials has become wider. For example, the maximum controlled particle size of rockfill dam materials has reached 0.8-1.0m, far exceeding the allowable size of indoor test instruments ( At present, a large triaxial instrument with a diameter of 30cm is commonly used in China, and the maximum control particle size is 5-6cm), which cannot be directly carried out in the laboratory. When determining the relative density filling standard of coarse-grained dam materials or performing related soil mechanics tests, it is necessary to check the oversize The particles are scaled down to reduce the original ingredients to th...

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Problems solved by technology

[0002] With the emergence of heavy-duty vibrating mills, the gradation range of engineering coarse-grained materials has become wider. For example, the maximum controlled particle size of rockfill dam materials has reached 0.8-1.0m, far exceeding the allowable size of indoor test instruments ( At present, a large triaxial instrument with a diameter of 30cm is commonly used in China, and the maximum control particle size is 5-6cm), which cannot be directly carried out in the laboratory. When determining the relative density filling standard of coarse-grained dam materials or performing related soil mechanics tests, it is necessary to check the oversize The particles are scaled down to reduce the original ingredients to the range that the indoor test equipment can carry

[0003] When conducting indoor tests on the original gradation of coarse-grained materials, two key technical problems need to be solved: one is how to reasonably determine the gradation after the scale reduction; the other is how to determine the sample preparation standards for indoor tests

However, due to the dry density scaling effect of the original grading coarse-grained material (Zhu Sheng et al., 2011), the compaction performance of the scaled grading deteriorates, and the indoor test adopts the same standard as the porosity of the original grading. When preparing samples, the density of the scaled-scale ingredients is much higher than that of the original-grade ingredients, so that the indoor scaled-scale test results greatly overestimate the mechanical property parameters of the original-graded coarse-grained materials, which can be used to calculate or evaluate high rockfill dams The stress-deformation characteristics of important structures such as dams are unsafe, which hinders the development of the construction of 300m super-high rockfill dams in China

[0006] It can be seen that the basis for determining the compaction standard for indoor test sample preparation after scale-down of engineering-graded coarse-grained materials with large particle sizes is not yet sufficient.

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