露天排土场不同排土工艺失稳机制对比试验研究

Comparative tests on failure mechanisms of waste dumps of open-pitmines with different dumping methods

排土工艺是影响排土场失稳机制的关键因素。以某露天铁矿外排土场为背景,采用底摩擦试验方法研究不同排土工艺条件下排土场的失稳过程,基于测点图像追踪技术获取排土场位移特征,重点分析4种排土工艺下排土场的稳定性和失稳机制。研究结果表明:(1)相同基底条件下正向堆置的压坡式排土场稳定性最好,其次为正向堆置的覆盖式排土场,再次是反向堆置的覆盖式排土场,反向堆置的压坡式排土场稳定性最差;(2)排弃渣土块度大小对排土场稳定性具有较大影响,以小块度排弃物为主的台阶易破坏,以大块度排弃物为主的台阶稳定性较好;(3)不同排土工艺下排土场的失稳机制具有明显差异,正向堆置排土场以中、上部坡体破坏为主,其中覆盖式模型的失稳机制表现为中、上级台阶的滑移→拉裂破坏,压坡式模型表现为中、上级台阶挤压→滑移破坏;反向堆置排土场以中、下部坡体破坏为主,其中覆盖式模型的失稳机制表现为中、下级台阶的滑移→拉裂破坏,压坡式模型失稳机制则表现为中、下级台阶滑移→拉裂→牵引复合式破坏并且破坏面积最大。研究成果可为露天矿排土场稳定性评价和排土工艺的选取提供借鉴和指导。

Dumping method is one of the key factors affecting the failure mechanism of waste dumps of open-pit mines.To reveal the failure mechanism of mine waste dumps with different dumping methods,a real waste dump was taken as a background and a series of base friction tests were conducted on four models.The failure process was comparatively analyzed through the graphical point-tracking technology.The results show that:(1)under the same base condition,the forwardly downslope dump has the highest stability level,followed by the forwardly covered dump,the reversely covered dump and the reversely downslope dump.(2)The block size of the waste material has a significant impact on the dump stability,and the stage mainly composed of small-size blocks is easier to collapse than that mainly composed of large-size blocks.(3)Failure mechanisms of waste dumps with different dumping methods are different.Exactly,the failure of the forward dumps mainly occurs at the upper and middle slope,among which the forwardly covered dump shows slip-cracking failure at the upper and middle stages while the forwardly downslope dump presents extrusion-slip failure in the upper and middle stages.In contrast,the failure of reverse dumps locates at the lower and middle slope,among which the reversely covereddump shows slip-cracking failure at the lower and middle stages but the reversely downslope dump showsslip-cracking-traction composite failure at the lower and middle stages with the largest damage area. The researchresults can provide reference and guidance for the stability evaluation of open-pit mine waste dumps and theselection of dumping methods.