深部采场采动过程中充填体控压作用机制及力学模型

Reasonable parameters (stiffness & strength) for pressure control model of backfill is one of the important ways to realize optimal balance between mining safety and backfill costs in open stoping with subsequent backfill of deep metal mines. However, few studies on contacting mechanism of rock-fill body have been done. The mining-induced response mechanism and analytical model for backfill stress during the process of mining and backfilling are still unclear. These lead to the unreasonable match between the design methods of backfill stiffness-strength and the stability of exposed backfill affected by surrounding rockmass deformation in deep stopes.. In this project, the methods of lab-test about the rock-fill contact mechanism and the numerical simulation about their coupled deformation, analytical calculation about the backfill stress and physical model test about exposed cemented backfill stability will be employed. Then the interacting mechanism of rock strain softening and backfill strain hardening and its constitutive model, the pressure control mechanism and stress analytical model of backfill under the action of surrounding rockmass in deep stopes, the three dimensional analytical model and methods for backfill stiffness-strength requirements in high pressure environment will be investigated and studied. In the end, an innovative design method for pressure control model of the backfill in deep stopes will be established. These have great theoretical significance and practical value to enrich the theory system of backfill mechanics and guide the backfill parameters design in deep metal mines.

合理确定采场充填体的控压作用及力学参数（刚度-强度）是实现深部金属矿空场嗣后充填采矿法开采安全和胶充成本最优平衡的关键方法和重要手段之一。而目前，岩石-充填体的接触耦合力学作用机理研究尚少，采-充时序过程中采场充填体应力的采动响应机制及其解析计算模型尚不明确，进而导致充填体刚度-强度设计方法不能与深部围岩变形作用下的充填体稳定性要求相匹配。.项目拟采用岩石-充填体接触力学试验及其耦合变形作用数值模拟、充填体应力解析计算及揭露稳定性的物理模型测试等手段和方法，探索研究岩石应变软化-充填体应变硬化的耦合作用机理及其本构模型、围岩采动变形作用下采场充填体的控压机理及充填体应力解析模型、高应力环境的采场充填体刚度-强度需求三维解析模型与方法，最终建立有基础创新性的深部采场充填体控压作用力学参数设计方法。对丰富发展金属矿充填体力学理论体系、指导深部金属矿充填体力学参数设计具有重要理论意义和实用价值。

我国金属矿山逐步进入深部开采，充填体-岩石接触机制、组合体力学特征研究不足，导致采场充填强度设计难考虑采动过程中充填体-围岩相互作用对其应力和强度影响，引起充填体参数设计难与其控压需求合理匹配，使矿山充填时或追求多加水泥（成本高）、或强度设计过低（不安全）。.项目攻关了采动过程中围岩与充填体相互作用及应力响应机制、高应力环境采场充填体控压机理及充填体刚度-强度需求的关键问题，取得如下成果：.（1）充填体-岩石接触面的内摩擦角大于相应充填体内摩擦角，但接触面的黏聚力则小于充填体黏聚力。接触面与相应充填体的强度参数存在线性换算方法。.（2）提高充填体的刚度参数，对充填体-岩柱组合体的峰值强度和残余强度的增强效应最显著，其次是增大充填体黏聚力、再次充填体内摩擦角的影响。.（3）随充填体黏聚力增加，其包围岩柱的峰后特征从应变软化过渡到应变硬化状态、残余承载强度增大，但充填体黏聚力存在临界值（600kPa），超过该值后继续增加充填体黏聚力不会明显提高岩柱-充填体的组合承载强度。.（4）充填体黏聚力低于50kPa，其应力随黏聚力增加而降低，可用Terzaghi模型解析采场充填体应力分布。充填体黏聚力超50kPa后，Terzaghi模型不再适用，需用考虑界限黏聚力的修正Terzaghi解析模型完成采场充填体拱应力计算。.（5）建立了考虑采充时序、相邻充填体间、充填体与岩石间接触作用的采场充填体强度需求解析方法，该法计算的典型采场充填体理论强度需求比常用的米切尔法高36%，并利用基于FLAC3D的充填体强度需求数值解校验了该法的可靠性，解决了以往米切尔法无法考虑深部采场采充时序过程的局限性。.（6）深部矿体采场采充时序过程中，原岩矿柱比充填体的应力高几十倍，充填体强度/刚度虽远低于原岩、但其可塑性和让压性使充填体控压作用更优。原岩矿柱控压体现为刚性支撑围岩闭合，充填体控压体现为应力隔离。