溜井放矿过程中贮矿段井壁动态应力分布特征研究

Research on Distribution Characteristics of Wall Dynamic Stress at Ore Storage Section of Ore-pass During Ore-drawing

溜井放矿过程中贮矿段井壁的磨损破坏程度与井壁动态应力的分布特征密切相关。以金山店铁矿主溜井为工程背景,基于Janssen公式,引入超压系数,推导贮矿段井壁动态应力的理论计算公式,计算不同高度处井壁动态应力的理论值;采用颗粒流程序模拟主溜井放矿过程,分析贮矿段井壁动态应力的分布特征;基于自主研发的溜井放矿相似试验平台,配合应变仪,对放矿过程中贮矿段井壁不同高度处的应变值进行监测,通过应变仪的率定参数将其转换为对应的动态应力值。将理论计算、数值模拟所得结果与相似试验所得井壁动态应力及井壁磨损分区范围进行对比。研究表明:理论计算、数值模拟、相似试验所得井壁动态应力的最大相对误差率在19%以内,验证了理论计算公式的合理性;三者所得井壁动态应力的均值在放矿口以上(5.0 m,15.0 m)范围内均超过了228 k Pa,在(15.0 m,30.0 m)范围内均不足204 k Pa,分别对应于相似试验中井壁的重磨损区及轻磨损区;井壁动态应力越大则井壁磨损程度越重,从力学角度解释了贮矿段井壁磨损破坏程度差异的原因。

The wear and damage degree of storage section wall is closely related to the distribution of dynamic stress in the process of ore-drawing in an ore-pass. Taking the main ore-pass of Jinshandian Iron Mine as an engineering background,and based on the Janssen formula,the theoretical formula for calculating the wall dynamic stress of ore storage section is derived by introducing the overpressure coefficient,and the theoretical values of wall dynamic stress at different height are calculated. The distribution characteristic of wall dynamic stress at storage section is analyzed by using the particle flow program to simulate ore-drawing process in the main ore-pass. Based on the independently-developed platform which is similar to the ore-drawing in ore-pass,with a strain gauge,the wall strain at different heights of ore storage section is monitored in the process of ore-drawing,and the corresponding dynamic stress value is converted by the rated parameters of the strain gauge. The dynamic stress of theoretical calculation and numerical simulation is compared to that of the similarity tests and to the wear range of ore storage wall. The results show that the maximum relative error rate of wall dynamic stress obtained by the three methods is within 19%,which verified the rationality of theoretical calculation formula. The average values of wall dynamic stress obtained by the three methods are all more than 228 k Pa at the area of ore out-drawing between 5.0 m and 15.0 m,and less than 204 k Pa at the area between 15.0 m and 30.0 m,which correspond to the heavy wear area and light wear area of the wall in similarity test,respectively. The higher wall dynamic stress,the heavier the wear degree of wall is. The reason for the degree difference of wall wear and damage at storage section is given in mechanics.