Method and tester for determining relative density sample preparation standard of laboratory scale test on coarse aggregate

Abstract

The invention relates to a method and a tester for determining a relative density sample preparation standard of a laboratory scale test on coarse aggregate, and belongs to the technical field of geotechnical testing. The method comprises the following steps: firstly, selecting graded coarse aggregate, and conducting a heavy vibrating roller extremum dry density test to obtain maximum dry density values of a field test; through a surface vibrator compaction manner, adjusting compaction parameters of the tester to obtain the maximum dry density values under different compaction manners and compaction parameters; then, determining selected equivalent compaction parameters under an indoor compaction manner to serve as a compaction standard of a laboratory maximum dry density test; finally, performing a laboratory relative density test on a scale material according to the compaction standard to obtain the extremum dry density of the scale material; according to a design index, to determining the sample preparation dry density or porosity of the laboratory scale test on the coarse aggregate through calculation. According to the method and the tester disclosed by the invention, by aiming at the scale problem of the original graded coarse aggregate, the influence of the scale effect of the coarse aggregate can be reduced, and the precision of the laboratory test on the coarse aggregate is effectively improved.

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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