【作者】 尚世明；

【导师】 朱万成；

【作者基本信息】 东北大学 ， 采矿工程， 2008， 硕士

【摘要】 混凝土作为一种典型的人造工程材料,在国防建设和民用建筑中被广泛采用。在采矿工程中,混凝土的使用表现为喷射混凝土和混凝土衬砌等。在动态载荷作用时,载荷在短时间内发生剧烈的变化,与静载荷作用的情形相比,应力波传播及其诱发的破裂是必须要考虑的过程。动态剥落是由于压缩应力波在自由面反射成为拉伸应力波,并达到材料的动态抗拉强度后而引起的一种拉伸破裂。由于动态压缩应力波亦可以引起混凝土衬砌的剥落破裂。因此,剥落破裂的研究受到土木、水电、建筑以及矿业等专业人员的广泛重视。本文应用RFPA-Dynamics数值模拟软件,在考虑混凝土的细观非均匀性的基础上,研究了应力波在混凝土中的传播规律,模拟出混凝土在冲击载荷作用下的剥落破裂过程。主要内容如下：(1)在假定混凝土为三相复合材料的基础上,建立混凝土材料的二维细观材料模型；(2)通过开展不同波形下混凝土剥落过程的数值模拟,探讨混凝土非均匀性和应力波形对于剥落破裂的影响,揭示混凝土动态剥落强度应变率效应的机制。(3)模拟混凝土支护巷道在冲击载荷下的剥落破裂过程,探讨加载条件对破坏位置及破坏程度的影响,分析不同应力波波形对于巷道稳定性的影响。更多还原

【Abstract】 Being a typical man-made engineering material, concrete is extensively used in the national defense engineering and civil engineering. In the mining engineering, for instance, the spray-concrete and lining are both the very important concrete structures. Compared with the mechanical responses of concrete under static loading, the stress wave propagation and the associated failure loading must be considered when the concrete is under the dynamics loading. Dynamics spalling is a kind of tensile failure when the compressive stress wave is reflected as the tensile stress and it attains the dynamics tensile strength of the materials. Since the dynamics spalling maybe one of the main mechanisms that lead to the failure of concrete lining, the dynamics spalling attracts the attentions of professionals from civil engineering, hydraulic engineering and mining engineering.RFPA-Dynamics, a professional numerical code that is capable of simulating the failure process of concrete under the dynamics loading, is used to study the stress wave propagation and the associated dynamics spalling when the heterogeneity of concrete at the mesoscopic level is incorporated. The main contents of the thesis are as follows:(1) At the mesoscopic level, a three-phase material model for characterizing the heterogeneity of the concrete is used to build the two-dimensional numerical model of concrete specimens.(2) After the numerical simulations on dynamics spalling of concrete, the influence of material heterogeneity and waveform of the applied stress waves on the dynamics spalling is discussed, and the mechanism related to the strain-rate dependency of tensile strength of concrete is clarified.(3) The concrete that are used as the supporting structure in underground opening are numerically simulated, the effect of stress waveforms on the failure positions and patterns is analyzed.更多还原