分层特性对充填体强度及破坏模式的响应特征分析

多次充填导致的充填体分层现象给矿山后续开采带来了许多未知的因素。本文采用室内实验的方法,设置1：4、1：6、1：8三种灰砂比;66％、67％、68％三种质量浓度;1、2、3三种分层数,排列组合了27组充填体。对各组充填体进行单轴压缩试验,探究分层特性对充填体强度的影响规律,并结合FLAC3D软件利用“分界面”功能分析不同分层的充填体进行单轴压缩实验时的受力状态与破坏模式的变化。结果表明：分层特性会影响灰砂比、质量浓度等参数与充填试件强度之间的作用关系,分层数越多时充填体强度随灰砂比、质量浓度提升的幅度越小;分层界面会改变试件单轴受压时的破坏模式,分层数的增加会使充填体破坏模式从平行于加载方向的张拉破坏转变为靠近上分层的剪切破坏再转变为贯穿两个分层面的张拉破坏,同时分界面处的剪切错动现象也更加明显。

Response characteristics of delamination characteristics to backfill strength and failure mode

The phenomenon of filling body delamination caused by multiple filling has brought many unknown factors to the follow-up support design of the mine. In this paper, three lime sand ratios of 1:4, 1:6 and 1:8 are set by indoor experiment; 66, 67 and 68 mass concentrations; 1. Two and three layers are arranged to combine 27 groups of filling bodies. Uniaxial compression tests were carried out on each group of backfill to explore the influence of delamination characteristics on the strength of backfill, and combined with FLAC3D software, the "interface" function was used to analyze the changes of stress state and failure mode of different layered backfill when conducting uniaxial compression tests. The results show that: (1) The delamination characteristics will affect the corresponding relationship between the lime sand ratio, mass concentration and the strength of the filling specimen. The greater the number of delaminations, the smaller the increase of the strength of the filling specimen with the lime sand ratio and mass concentration; (2) The delamination interface will change the failure mode of the specimen under uniaxial compression. When the number of delaminations increases from one to three, the failure mode changes from tensile failure parallel to the loading direction to shear failure close to the upper delamination to tensile failure through the two delaminations. At the same time, the shear dislocation phenomenon at the interface is more obvious.