深部动载作用下超大断面硐室群锚固围岩破坏失稳机制研究

深部近距离超大断面硐室相互影响导致围岩应力集中且破裂范围大,特别是在动载扰动下易发生破坏失稳现象。首先以龙固煤矿井下煤矸分离系统超大断面硐室群为研究背景,通过数值模拟软件FLAC3D建立计算模型,利用内置动力模块研究了不同硐室间距和动载强度条件下深部超大断面硐室群围岩变形破坏规律。模拟结果表明:随着硐室间距减小,围岩变形程度逐渐增大并最终发生整体破坏,动载扰动下硐室群临界间距范围较静载时增大了约33.3%~50%;随着动载强度增加,锚固围岩响应逐渐增强,发生破坏失稳的临界动载强度约为4.0~4.5 MPa。基于弹塑性力学和弹性波理论,构建了动静组合载荷下锚固围岩力学模型,获得了深部动载下硐室群锚固围岩破坏失稳判据,并将锚固围岩划分为3个状态:整体稳定、静态破坏和动态失稳,在此基础上获得了硐室群破坏失稳临界间距的解析表达式。现场算例计算及现场监测验证了理论分析的合理性及可行性。该研究可为深部动载影响超大断面硐室群布置设计及围岩稳定性控制提供理论依据。

高阶煤压裂液伤害机理研究

为了分析压裂液对高阶煤层压裂后产能的影响,从压裂液对高阶煤的伤害研究入手,结合沁水盆地七元矿区的实际压裂情况,采用压裂液伤害实验与电镜扫描分析相结合的方法,研究了不同类型压裂液对高阶煤岩的伤害原因,进一步揭示了压裂液对高阶煤岩的伤害机理。

Experimental and numerical simulation of loading rate effects on failure and strain energy characteristics of coal-rock composite samples

The deformation and failure of coal and rock is energy-driving results according to thermodynamics.It is important to study the strain energy characteristics of coal-rock composite samples to better understand the deformation and failure mechanism of of coal-rock composite structures.In this research,laboratory tests and numerical simulation of uniaxial compressions of coal-rock composite samples were carried out with five different loading rates.The test results show that strength,deformation,acoustic emission(AE)and energy evolution of coal-rock composite sample all have obvious loading rate effects.The uniaxial compressive strength and elastic modulus increase with the increase of loading rate.And with the increase of loading rate,the AE energy at the peak strength of coal-rock composites increases first,then decreases,and then increases.With the increase of loading rate,the AE cumulative count first decreases and then increases.And the total absorption energy and dissipation energy of coal-rock composite samples show non-linear increasing trends,while release elastic strain energy increases first and then decreases.The laboratory experiments conducted on coal-rock composite samples were simulated numerically using the particle flow code(PFC).With careful selection of suitable material constitutive models for coal and rock,and accurate estimation and calibration of mechanical parameters of coal-rock composite sample,it was possible to obtain a good agreement between the laboratory experimental and numerical results.This research can provide references for understanding failure of underground coalrock composite structure by using energy related measuring methods.

Numerical simulation research on response characteristics of surrounding rock for deep super-large section chamber under dynamic and static combined loading condition

The stability control of surrounding rock for large or super-large section chamber is a difficult technical problem in deep mining condition.Based on the in-site geological conditions of Longgu coal mine,this paper used the dynamic module of FLAC3D to study the response characteristics of deep super-large section chamber under dynamic and static combined loading condition.Results showed that under the static loading condition,the maximum vertical stress,deformation and failure range are large,where the stress concentration coefficient is 1.64.The maximum roof-to-floor and two-sides deformations are 54.6 mm and 53.1 mm,respectively.Then,under the dynamic and static combined loading condition:(1)The influence of dynamic load frequency on the two-sides is more obvious;(2)The dynamic load amplitude has the greatest influence on the stress concentration degree,and the plastic failure tends to develop to the deeper;(3)With the dynamic load source distance increase,the response of surrounding rock is gradually attenuated.On this basis,empirical equations for each dynamic load conditions were obtained by using regression analysis method,and all correlation coefficients are greater than 0.99.This research provided reference for the supporting design of deep super-large section chamber under same or similar conditions.