充填体与围岩接触成拱作用机理及强度模型研究

发布时间：2018-04-19 14:49

本文选题：阶段空场嗣后充填法 + 充填体力学　；参考：《北京科技大学》2017年博士论文

【摘要】：地下金属矿山中,阶段空场嗣后充填法是充填法与空场法的有机结合,代表了大规模高效率绿色清洁采矿的发展方向。但是该法中一步骤采场胶结充填体的胶充成本(水泥等添加)占充填总成本70%以上,如何在确保充填体揭露稳定性的同时优化控制胶充成本是制约安全经济充填采矿的瓶颈问题。为此,本文采取理论分析、解析计算、数值计算、实验测试、物理模型验证和矿山应用验证相结合的研究手段,旨在突破充填成拱作用机理及影响因素分析、充填体拱应力计算和强度需求计算中的关键瓶颈,为两步骤阶段空场嗣后充填法中采场充填体强度需求的优化设计提供理论依据和方法参考。(1)定义了一种锯齿型接触单元以定量描述实际采场围岩的表面特征,探索了充填体与围岩之间嵌入线性平滑、非线性粗糙接触单元对充填体应力成拱效应的影响规律,研究了充填体拱应力分布对接触面性质(粗糙度指标、剪切强度参数)和充填体尺寸及物理力学参数的响应机制,得出了更具普适性的根据采场围岩边壁特征进行采场充填体拱应力计算的数值模型与方法。(2)分析了用于充填体强度需求和稳定性计算的经典Mitchell法的提出过程,利用FLAC3D数值还原模拟了校验Mitchell法的物理模型试验,对比研究了不同尺寸条件下充填体强度与揭露稳定性的关系,获取了经典Mitchell法的适用条件,得到了揭露后胶结充填体的潜在滑动破坏模式及其描述方法。(3)研究了固结排水长期强度状态下,二步骤采场非胶结充填体、揭露前和揭露后的一步骤采场胶结充填体的三维拱应力分布模式,并分别建立了各采场充填体拱应力的三维解析计算模型,得出了三维成拱状态下非胶结充填体-胶结充填体-采场围岩间的应力传递作用规律及接触力学边界表征方法。(4)探索了阶段空场嗣后充填法采充时序过程中,不同工况条件下非胶结充填体对胶结充填体的侧压作用机制,建立了一步骤采场胶结充填体强度需求的三维解析计算模型,与FLAC3D模拟搜索的强度需求三维数值解综合对比后,获得了采场充填体强度需求理论解的最优解析计算模型与方法。(5)以工程依托矿山原位采场充填体中钻孔取芯试样的强度实测数据为样本,研究了采场充填体强度分布离散性的数理统计学概率表征,据此定义了一种安全系数的浮动选取方法,定量描述了矿山现阶段的整体充填技术水平和充填质量控制效果,建立了采场充填体"强度需求理论解→实际充填质量反馈→安全系数浮动选取→实际强度需求指标"的动态优化设计模型。
[Abstract]:In underground metal mines, the backfilling method is an organic combination of filling method and open-pit method, which represents the development direction of large-scale and high-efficiency green and clean mining.However, the filling cost (cement addition) of the stope cemented filling body in one step of the method accounts for more than 70% of the total filling cost.How to optimize and control the filling cost while ensuring the stability of the backfill is the bottleneck of the safe and economical backfill mining.Therefore, this paper adopts a combination of theoretical analysis, analytical calculation, numerical calculation, experimental testing, physical model verification and mine application verification to break through the mechanism of filling arch formation and the analysis of influencing factors.The key bottlenecks in stress calculation and strength requirement calculation of filling arch,This paper provides a theoretical basis and method reference for the optimization design of the strength requirement of stope backfill in the two-step open-pit subsequent filling method. A zigzag contact unit is defined to quantitatively describe the surface characteristics of the surrounding rock in the actual stope.The effect of linear smooth and nonlinear rough contact element on the stress arch effect between backfill and surrounding rock is explored. The effect of arch stress distribution on contact surface properties (roughness index) is studied.The response mechanism of the shear strength parameter and the size of the filling body and the physical and mechanical parameters,A more general numerical model and method for calculating arch stress of stope filling body according to the characteristics of side wall of stope surrounding rock are obtained. The process of the classical Mitchell method for calculating the strength demand and stability of stope is analyzed.The physical model test of verifying Mitchell method is simulated by FLAC3D numerical reduction. The relationship between the strength of the filling body and the exposure stability under different size conditions is compared and the applicable conditions of the classical Mitchell method are obtained.In this paper, the potential sliding failure mode and its description method of post-cemented backfill are obtained. The non-cemented backfill in two-step stope under the condition of long-term strength of consolidated drainage is studied.The three dimensional arch stress distribution model of cemented filling body of stope before and after disclosure is established, and the three dimensional analytical calculation model of arch stress of each stope filling body is established respectively.The law of stress transfer between non-cemented backfill, cemented backfill and stope surrounding rock and the boundary representation method of contact mechanics under the condition of three-dimensional arch formation are obtained.Based on the lateral pressure mechanism of non-cemented filling under different working conditions, a three-dimensional analytical calculation model of strength requirement of one-step stope cemented backfill is established, which is compared with the three-dimensional numerical solution of strength requirement searched by FLAC3D simulation.The optimal analytical model and method for the theoretical solution of the strength requirement of stope backfill are obtained.This paper studies the mathematical statistical probability representation of the discrete strength distribution of stope filling body, defines a floating selection method of safety factor, and quantitatively describes the overall filling technology level and filling quality control effect at the present stage of the mine.A dynamic optimum design model for stope backfill is established, which is based on the theory of strength demand theory and the feedback of practical filling quality and the floating of safety factor to select the index of actual strength demand.
【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TD853.34

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