Pervious concrete is an innovative eco-friendly construction material. Through the application of mineral admixtures and microscopic analysis to optimize its performance and analyze its mechanisms, its traits as a sustainable building option may be further improved. This study primarily examines the impact of the optimal blend quantities of fly ash, silica fume, and reinforcing agent on the attributes, micro-morphology, and phase composition of porous concrete. The optimal admixture was chosen after analyzing the effects of various factors on the mix ratio and properties of permeable concrete. To understand the degree of impact, performance tests were conducted on the 28-day compressive strength, water permeability coefficient, and porosity. Furthermore, the micro-mechanisms of the admixtures and reinforcing agents on the properties of permeable concrete were analyzed from a microscopic point of view using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. This research found that the advantageous properties of permeable concrete were enhanced by the simultaneous integration of appropriate quantities of fly ash, silica fume, and reinforcing agent. This resulted in a 28-day compressive strength of 18.33 MPa and a permeability coefficient of 8.27 mm/s. Compared with the unadulterated mineral admixture, the optimal admixture of fly ash, silica fume, and reinforcing agent at the same time increased the 28-day compressive strength by about double; the permeability coefficient was reduced by 36%, but it was still at a high level; and the measured porosity did not differ much from the designed porosity. Through thorough microanalysis, the hydration reaction was significantly improved, which could enhance the microstructure and pore structure of the concrete. This was supported by a substantial increase in the macroscopic compressive strength and a decrease in the water permeability coefficient, which were consistent with the aforementioned enhancement found in the microanalysis.

淮北临涣煤矿7煤与下部9煤的煤层间距平均为28.5 m,属于近距离煤层,开采方式为上行开采,此时7煤作为被保护层,受到9煤开采影响,回采巷道可能存在围岩变形程度大,支护方式选取困难的问题.以被保护层7111工作面机巷为研究对象,进行支护技术研究.通过理论分析巷道变形与破坏机理后,针对不同巷道地段设计了3种支护方案,运用FLAC3D软件模拟下煤层开采后被保护层回采巷道在3种支护方式下围岩应力分布特征和顶底板、两帮位移及塑性区范围.结合现场实测分析后,表明支护方案和参数设计比较合理,为上行开采回采巷道支护提供了有效的方法.

Aiming at the difficulties during the support of high-stress fractured soft rock roadway in deep mine, a comprehensive surrounding rock management method of bolt-net-cable-grout coupling support is proposed and the mechanism of interaction between coupling support and surrounding rock is analyzed by numerical simulation. The effectiveness of the coupling support is proved by an application in the east wing return-air roadway in the Qingdong Coal Mine of Huaibei Mining Group. The results show that the surrounding rock plastic zone near the sidewall and floor of high-stress fractured soft rock roadway is larger than that near the roadway roof, and its distribution range can be reduced by using the coupling support. And, the coupling support can improve the reliability of roadway support and the stability of surrounding rock by reducing the axial stress of anchor bolts, the stress concentration of surrounding rock caused by anchor bolt, the roadway surface displacement, and deep displacement of surrounding rock.

962工作面是海孜煤矿86采区9#煤层首采面,为了了解工作面矿压规律,对962工作面进行了矿压观测,分析了在近距煤层开采过程中,工作面来压显现规律、支架分布特征及运行情况、支承压力分布规律及围岩破坏特征,结果表明,受762工作面开采影响,沿962工作面倾斜方向来压具有差异性,且来压强度较小,持续时间较长,矿压观测同时表明,回采巷道围岩移动变形仍属有限,现有支护能满足安全开采要求.

How to judge the elastic-plastic deformation as well as the mechanical behavior of surrounding rock after the tunnel excavated , has been a focus of research .This paper considers the damage characteristics of rock materi-al, established the elastic-plastic damage model of roadway surrounding rocks , analyzed the elastic-plastic stress field and the scope of circular roadway surrounding rocks when the lateral pressure coefficient equals 1.0.Combi-ning with the concrete examples , reached a conclusion that within the same scope of plastic range , the λ/E ratio increases,the supporting resistance increases;when the primary rock’s stress fixed, with the raise of λ/E ratio,the plastic zone of roadway surrounding rocks increases as well .Research indicates that , taking the damage effect into account , the analysis results could be much more close to the reality ,so that it provides the theory basis to analyzing the stability of roadway surrounding rocks and the reasonable selection of supporting form and intensity .