泥质弱胶结岩体组构和力学性质与环境效应耦合演化机理

The Jurassic in eastern Inner Mongol mining area is mostly argillaceous weakly cemented rock mass with high clay mineral and porosity, loose structure and low strength. There are many engineering problems such as difficult anchor, low load-bearing capacity and severe deformation. The effects of environmental parameters to macro and micro structures and mechanical properties are studied. Firstly, based on the analysis of rock mineral composition and occurrence environment, rock mechanical tests under different stress paths and environmental effects are carried out to reflect the characteristics of static and dynamic pre-reinforcement and weathering, rupture evolution process in excavation. Then the structure reorganization tests of cracked rock mass under the coupling condition of stress state and environment effect are conducted to reveal the structure reorganization and strength regeneration process of the rock mass under the combination of support and stress, reflecting the influence of stress state, mineral composition, environmental temperature, humidity and time factor, and obtain the key control parameters of rock mass structure reorganization. Then loading-unloading tests and creep tests of reorganized rock samples are carried out under controlled environment combined with video microscopy analysis to reflect the evolution law of macro meso structure and mechanical properties of reorganized rock mass. The segmented 3D elastic-plastic and visco-elastoplastic constitutive model are established to reveal the evolution process of rupture, structure reorganization and re-bearing of argillaceous weakly cementated rock mass and the coupling mechanisms of argillaceous weakly cemented surrounding rock and support structure. The achievements will lay the experimental and theoretical foundation for solves the stable control problem of argillaceous weakly cemented surrounding rock.

蒙东矿区侏罗系地层多为泥质弱胶结岩体，具黏土矿物含量和孔隙率高、结构疏松强度低等特点，存在难以锚固、自承载力低、剧烈变形等问题，针对环境参数对其宏细观组构和力学性质的影响开展研究。首先在分析岩体矿物组成与赋存环境特性基础上，通过不同应力路径与环境效应下岩石试验，反映静力与动力预加固特性和开挖中风化、破裂演化过程；然后利用破裂岩体进行应力状态和环境效应耦合条件下岩体结构重组试验，揭示在支护与地应力共同作用下岩体结构重组和强度再生过程，反映应力状态、矿物组成、环境温湿度、时间因素的影响规律，获得岩体结构重组的关键控制参数；进而开展控制环境下重组岩样加卸载与蠕变试验，结合视频显微分析，反映重组岩体宏细观组构与力学性质的演化规律，并建立分段三维弹塑性和黏弹塑性本构模型，揭示泥质弱胶结岩体破裂、重组与再承载演化全过程和泥质弱胶结围岩与支护间的耦合作用机理，为解决其稳定控制问题奠定试验与理论基础。

中生代晚侏罗世和白垩世煤系分布泥质弱胶结岩体，受到环境和应力扰动后，工程围岩发生大变形，阻碍了该区域煤炭资源的安全和高效开采。室内和现场试验表明：一定环境和支护强度条件下损伤泥质弱胶结岩体可实现结构重组，承载能力增强。为揭示泥质弱胶结岩体组构和力学性质与环境效应耦合演化机理，确定合理围岩变形控制方案及设计参数，保证巷道在掘进和工作面回采期间围岩的稳定，本项目包含四部分研究内容：.（1）通过动力学试验和注浆试验，研究泥质弱胶结岩体预加固状态下结构强化机制。试验表明：一定强度的动力冲击和注浆预加固可排出孔隙内的水分，粘聚力和内摩擦角增加，增强了工程围岩的承载能力；.（2）通过风化试验和力学试验等研究了基于环境效应下泥质弱胶结岩体开挖风化损伤机制与结构破裂演化特性，发现存在临界环境湿度控制岩体与环境之间的水分迁移方向；弹性模量E随着试样含水率降低呈线性增加，脆性随之增强；存在临界环境湿度 50% RH，当RH小于该值时，试样单轴抗压强度开始降低，但脆性增强；风化泥岩破坏形式主要为拉伸破坏。.（3）基于环境效应下泥质弱胶结破裂岩体结构重组机制与力学性质演化规律研究。利用岩土体重组试验装置，得到不同类型结构重组试样，并对结构重组岩体分别开展静力和扰动流变试验，揭示了结构重组岩体静力和动力学性质，一定强度的冲击，有利于增强扰动区结构重组岩体的抗变形能力。.（4）基于风化条件下不同应力路径损伤泥质弱胶结岩体结构重组力学特性，结合细观结构特征，分别建立结构重组泥岩细观和宏观力学本构模型，揭示结构重组泥岩承载机理；基于数值分析方法研究扰动区结构重组泥质弱胶结岩体与支护结构耦合变形机理，提出了合理支护方案和支护参数。.该项目意在实现泥质弱胶结煤系开拓巷道和回采巷道的稳定性控制，研究成果在蒙东地区华润电力（锡林郭勒）煤业有限公司西一矿实践成功，加速了泥质弱胶结煤系煤炭资源的开发。