In order to deeply explore the effect of coal rock mass elastic-plastic deformation on structu-ral weak planes,fracturing experiments were conducted according to the combination relationship of crack initiation position,fracturing direction,and bedding direction.Non-metallic ultrasonic detectors and acoustic emission were used to monitor the fracturing process,and the fracturing effect was compre-hensively evaluated from the aspects of crack propagation morphology,crack width,and permeability flow rate.Corresponding explanations were given from the perspective of energy.The experimental re-sults show that the fracturing of the overlying strata is better than that of the coal seam,and vertical bed-ding fracturing is better than parallel bedding fracturing.The fracturing effect is best in the vertical bed-ding direction,and the crack propagation morphology is more complex,forming an"O"shape.Its ave-rage permeability coefficient is 6.6 mm/s,which is 1.10 times that of parallel bedding.The cracks propagate from the overlying rock of the roof to the coal block,and under the same initiation energy,3.08 to 338 times equivalent length cracks can be formed in the coal block.
以华北地区某城市关于城市体检中的多元包容指标为研究对象,结合熵值法对城市多元包容的评价指标进行计算,建立磷虾群算法-投影寻踪模型确定指标权重,与华北地区相邻10个城市的多元包容发展水平进行对比,判断相关指标对城市包容性发展水平的影响程度.对于不同发展水平的城市因地制宜地提出不同的发展要求.
为了研究软弱夹层倾角和含水率对含软弱夹层复合岩体的力学性质和破坏特征的影响,通过室内制样,制作了含5 种不同倾角和3 种不同含水率软弱夹层的复合岩体,并进行室内单轴试验.研究表明:随着倾角的增大,软弱夹层的峰值强度和变形模量减小,峰值点应变增大;实验中,无论软弱夹层倾角为多少时,软弱夹层两侧最先破坏,当软弱夹层倾角θ=15°、20°和 25°时,软弱夹层不仅发育有两侧破坏,还发育始于左侧顶面止于右侧底面的贯通斜裂纹,并且也通过理论部分研究推测出对应的破坏模式;当软弱夹层倾角不变,随着软弱夹层含水率的增大,软弱夹层的峰值强度和变形模量先增大再减小,峰值强度点应变先减小后增大,含水率ω=8%试样的承载能力最强,此时软弱夹层的峰值强度和变形模量最大.
以苏州地区地铁基坑工程为研究背景,结合实际工程数据与数值模拟结果,分析插入比和基坑稳定与变形的关系.通过数值仿真明确基坑隆起失效时滑动面位置及其与插入比和基坑深度的关系,提出了确定滑动面位置的计算公式,改进了抗隆起稳定性分析中圆弧滑动法的滑动半径.结果表明:建立的滑动面位置确定公式可以较准确地预测苏州基坑隆起失效时滑动面位置;在此基础上,改进的隆起稳定性计算方法所确定的插入比与现有地基承载力法的计算结果吻合度较好,相较于传统圆弧法得到的插入比降低了41%,优化了地铁基坑支护结构的插入比设计.
针对因岩石力学性能劣化而诱发的工程灾害,以砂岩为研究对象,开展不同裂纹倾角下分级循环加载试验,分析了裂纹倾角对砂岩力学特性和裂纹扩展特征的影响;结合声发射频谱特征对微裂纹的发展情况进行了分析,最后利用关联维数对其变形破坏的有序度进行定量描述.结果表明:随着裂纹倾角的增大,试件的峰值荷载呈逐渐降低的趋势,但是预制裂纹的扩展无明显规律.其中频域信号的出现具有一致性,说明岩石内部微裂纹的萌生、发育、扩展形成大尺度裂纹具有同步性.岩石变形破坏的有序度可用关联维数进行定量描述,表现为关联维数越大,岩石破坏越复杂,其中关联维数变化幅度可以表征岩石内部裂纹的发展剧烈程度.
