3DEC modeling on effect of joints and interlayer on wave propagation

1 Introduction Natural rock mass is not homogeneous, and it is full of various weak planes with different structures and different geological mechanisms, such as fractures, joints, and cracks. These structural weak planes seriously hinder and affect the …     

Simplified design of rock cavern concrete lining to resist shock loading

A simplified method was proposed for the design of concrete lining in underground rock cavern/tunnel against shock loading. The loading may result from the detonation of explosives on ground surface or ground penetration projectiles exploding adjacent to the cavern/tunnel. The resulting problem necessitates the solution of the dynamics of a beam loaded by a transient pressure uniformly distributed over the span. According to mechanical characteristics of the system with rock bolt and shotcrete, a dynamic support design method based on equivalent single degree of freedom (SDOF) was put forward. The SDOF method was applied to obtaining the maximum displacement at the mid-span of the beam, which is often the controlling factor in the blast-resistant design. In the formulation of the problem, the proposed method combines the phenomena of spalling and structural dynamics theory. An example is provided to demonstrate the applicability of this simplified method.     

Constitutive model of rock under static-dynamic coupling loading and experimental investigation

1 Introduction Rock fragmentation, boring, explosive, rockburst etc in engineering domain of mineral are almost concerned with cracking of rock experiencing dynamic loading, and a plenty of results have been obtained[1]. But the related studies are almos…     

采矿方案的模糊优选

采矿方案选择受多种因素的影响,而这些因素又带有极大的模糊性、随机性和未知性,传统的采矿方案选择容易受到主观经验的左右而不能正确反映实际情况.应用模糊数学优选法,将采矿过程中的各种模糊或主观因素转化为数学形式,根据各采矿方案的技术经济指标及力学分析结果,将各方案的评价指标量化分析,使方案的评价和选择更加科学、合理、可靠.     

“三下”矿体开采研究

在参考国内外“三下”矿体开采经验的基础上，给出了“三下”矿体开采的典型实例，结合多年“三下”矿体开采的工程实践，总结了“三下”开采的现有理论，提出了“三下”矿体开采的一般措施。     

屈曲型岩爆的发生机制及其时效性研究

为分析深部巷道围岩层裂薄板结构的形成机制和屈曲型岩爆发生的力学机理,采用数值模拟方法对深部巷道开挖过程中围岩主应力的分异演化规律进行了研究。基于三参量黏弹性本构关系,以屈曲型岩爆的层裂薄板结构为力学模型,推导出了二向受力下屈曲型岩爆的压屈时效方程,探讨了不同应力状态下屈曲型岩爆的时效特征。结果表明:在以垂直应力为主导的巷道在掘进过程中,巷道顶部和底部的主应力水平在逐步减小,岩体能量逐步释放;而巷道两侧边墙的主应力出现严重的分异现象,切向应力变大而轴向应力减小,岩体能量向两侧转移并大量积聚。以水平应力为主的巷道在掘进过程中,围岩应力状态的演化过程及能量积聚特征与此相反。围岩层裂薄板结构形成后,在切向应力和轴向应力的二向应力作用下发生蠕变弯曲变形,经过一段时间,当变形达到某一限值时,层裂薄板结构就会发生屈曲失稳破坏并释放岩体内积聚的弹性变形能,产生延迟岩爆现象。     

边坡稳定性分析中滑楔法的误差分析及其改进

边坡稳定性分析的极限平衡理论中,仅考虑力的平衡的简化法(也称滑楔法)因其计算简便、快捷,广泛应用于国内外工程界.实践证明,对于圆孤滑面,滑楔法与严格条分法精度相当,但对于非圆孤滑面往往出现较大误差.根据对条间力倾角的不同假定情形,将滑楔法统分为第一类滑楔法和第二类滑楔法.建立了任意折线滑面边坡模型,以此分析滑体几何要素...     

基于AutoCAD和ANSYS的FLAC~(3D)复杂地质体建模

FLAC3D在地下复杂地质体实体建模及网格划分方面存在弊端。通过AutoCAD进行三维建模,将生成的AutoCAD图导入ANSYS中,可实现ANSYS的快速建模;应用ANSYS有限元程序可以快速便捷地进行网格划分,将划分后的网格文件利用ANSYS_TO_FLAC3D接口程序将其转换为FLAC3D可识别的FLAC文件。最后FLAC3D调用FLAC文件,从而实现复杂地质体的建模。详细阐述了AutoCAD、ANSYS在FLAC3D建模中的作用,并结合工程实例,验证其可行性和有效性。     

火电机组蒸汽在线钠表测量准确性研究

通过比较二阶微分火焰光谱法、离子色谱法和在线钠表法测量蒸汽中钠离子的准确性,检验了Orion、Swan、Polymetron等公司生产的蒸汽在线钠表的测量结果。表明:在保证仪表的最佳工况下,目前火电机组蒸汽在线钠表能够满足蒸汽中痕量钠离子准确测量的要求。在线钠表的测量准确性受电极性能、流体流速、碱化剂浓度、外界干扰等因素的影响,应定期对仪表进行清洁维护保养。     

Calibration of split Hopkinson pressure bar system with special shape striker

In order to present basic guidance for system calibration of split Hopkinson pressure bar(SHPB) with the special shape striker,wave characteristics and dynamic responses of SHPB under striker impact were analyzed.Stress generated by the special shape striker tends to have a half-sine waveform and has little wave dispersion during its propagation.Impact velocities of the special shape striker and peak values of generated stress still have linear relation but with a different coefficient from that of cylindri...