Backfilling is a common practice in the mining industry and the backfilling performance plays a significant role in supporting the surrounding rock mass. To evaluate the backfilling performance, an experimental apparatus has been developed to understand how backfill affects the compressive strength of sandstone specimens in the laboratory. Pebbles were selected to model the backfill and divided into six groups with different particle sizes using a set of standard sieves. The backfilling pebbles with three types of particle size compositions were then produced, i.e. single gradation, two adjacent gradations, and increasingly widening gradations. A series of compressive tests were carried out to study the mechanical behavior of the sandstone specimens confined by these pebbles. The effects of the gradations of the filled pebbles on the peak and residual compressive strengths were analyzed. It is found that the increasing amount of the compressive strength is over 10% in most cases, even up to 20%. Based on the experiment data, the increasing amount was also estimated theoretically under some assumptions and it further confirmed the experimental results. The effects are closely related to the gradations of the filled pebbles except for their dense degree.

回填是采矿业的常见做法，回填性能在支撑围岩方面起着重要作用。为了评估回填性能，开发了一种实验装置来了解回填如何影响实验室中砂岩试样的抗压强度。选择鹅卵石对回填进行建模，并使用一组标准筛将其分为六组，具有不同的粒径。然后生产具有三种粒度组成的回填卵石，即单一级配、两个相邻级配和逐渐加宽的级配。进行了一系列压缩试验以研究被这些卵石约束的砂岩试样的力学行为。分析了填充卵石的级配对峰值和残余抗压强度的影响。发现抗压强度的增加量在大多数情况下超过10%，甚至高达20%。在实验数据的基础上，在一些假设条件下，也对增加量进行了理论上的估计，进一步证实了实验结果。其效果与填充卵石的等级密切相关，除了它们的致密程度。