Mechanical retaining effect of intermediate bridge on slope of adjacent open pit
WANG Dong,LIANG Zuchao,LI Guanghe,LI Xuejian,ZHOU Zhiwei
露天煤矿分坑开采时,临时中间桥的合理布设与拆除对于控制边坡稳定性极为重要。 为解 决多坑并行剥采时,边坡与中间桥的动态协同设计难题,实现矿山安全生产和经济效益兼顾,对中 间桥支挡效应的定量表征方法与该种效应下的边坡稳定性计算方法进行研究。 将中间桥视为一种 特殊的边坡支挡结构,在构建边坡与中间桥三维力学模型的基础上,结合中间桥与边坡的相对位置 以及自身的空间形态,将中间桥沿边坡倾向划分为 3 个区域,基于摩尔-库伦抗剪强度理论,分区 推导了中间桥三维支挡效应的数学表达式,从理论上揭示了中间桥支挡效应与其断面面积及体积 的定量关系;由中间桥三维支挡效应产生的实质出发,应用合并同类项方式,提出了中间桥三维支 挡效应的二维等效方法,实现了等效黏聚力 cd 与等效内摩擦角 φd 的定量表征,阐明了中间桥空间 形态参数对支挡效应及边坡稳定性的影响规律。 研究结果表明:I区等效黏聚力 cd 即为中间桥底 界面的黏聚力 cj ,II区和III区等效黏聚力 cd 与中间桥底宽 d 呈正相关一次函数关系,各区域等效摩 擦因数 tan φd 均与中间桥底宽 d 呈正相关一次函数关系,与桥高 h、底角 α 的余切呈负相关一次函 数关系;工程示例中边坡稳定系数 Fs 随中间桥桥高 h、底角 α 增大而增大,上升梯度逐渐减小,且与 底宽 d、桥长 b 呈正相关一次函数关系。 成果可应用于露天煤矿中间桥形态参数的动态优化设计 以及中间桥支挡作用下的边坡稳定性治理。
During the subpit mining of surface coal mine,the reasonable establishment and removal of temporary intermediate bridge is very important to control the stability of slope. In order to solve the problem of dynamic collaborative design of slope and the intermediate bridge in multi pit parallel strip mining,and to achieve both safe production and economic benefits,the quantitative characterization method of the supporting and retaining effect of intermediate bridge and the calculation method of slope stability under this effect are studied. The intermediate bridge is regarded as a special slope retaining structure. On the basis of constructing the three dimensional mechanical model of slope and the intermediate bridge,combined with the relative position of the intermediate bridge and the slope and its own spatial shape,the intermediate bridge is divided into three zones along the slope inclination. Based on the Mohr Coulomb shear strength theory,the mathematical expression of the three dimensional supporting and retaining effect of the intermediate bridge is derived in different zones,and the quantitative relationship between the supporting and retaining effect of the intermediate bridge and its cross sectional area and volume is revealed theoretically. Starting from the essence of the three dimensional supporting and retaining effect of the intermediate bridge,by using the method of merging similar items,a twodimensional equivalent method of the three dimensional supporting and retaining effect of the intermediate bridge is proposed. The quantitative representation of equivalent cohesion cd and equivalent internal friction angle φd realized,and the influence of spatial shape parameters of the intermediate bridge on supporting and retaining effect and slope stability is expounded. The results show that the equivalent cohesion cd in zone Ⅰ is the cohesion cj of the interface at the bottom of the intermediate bridge,and there is a positive correlation between the equivalent cohesion cd in zone Ⅱ and Ⅲ and the width d of the bottom of the intermediate bridge. The equivalent internal friction coefficient tan φd of each zone is positively correlated with the bottom width d of the middle bridge and negatively correlated with the bridge height h and the cotangent value of the bottom angle α. In the engineering example,the slope stability coefficient Fs increases with the increase of the height h and bottom angle α of the intermediate bridge,and the rising gradient decreases gradually and has a positive correlation with the bottom width d and the bridge length b. The results can be applied to the dynamic optimization design of morphological parameters of the intermediate bridge in an open pit coal mine and the treatment of slope stability under the action of intermediate bridge support.
Mechanical retaining effect of intermediate bridge on slope of adjacent open pit
主办单位:煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会