约束混凝土抗侵彻机理与工程模型研究

发布时间：2018-11-29 12:43

【摘要】：混凝土作为军事和民用工程中应用最为广泛的建筑材料,其抗侵彻问题的研究具有重要意义。约束混凝土的抗侵彻能力优于无约束混凝土,然而目前有关约束混凝土抗侵彻性能和机理的研究较少。本文基于现有混凝土侵彻试验,采用理论分析和数值模拟相结合的方法,开展了刚性弹侵彻约束混凝土厚靶问题研究,为约束混凝土在遮弹结构中的应用提供了理论支撑,具有重要的理论意义和应用价值。本文主要内容如下:1、提出了一个刚性弹侵彻半无限混凝土靶工程模型。针对Mohr-Coulomb屈服准则和Griffith准则的局限性,提出了粉碎区混凝土采用Hoek-Brown准则的空腔膨胀模型,得到了静阻力的解析解,建立了新的半无限混凝土侵彻深度工程模型。与现有典型侵彻试验和侵彻深度公式对比表明:本文提出的基于Hoek-Brown准则的球腔公式普适性较好,且在理论性上更具优势。2、建立了约束混凝土的准静态柱形和球形空腔膨胀理论。基于径向受弹性约束的有限直径模型和Hoek-Brown准则,得到了约束混凝土柱形和球形空腔准静态膨胀的解析解。通过算例,分析了空腔膨胀过程以及各影响因素,结果表明:约束混凝土的空腔膨胀过程不同于半无限混凝土介质,其空腔壁压力在膨胀过程中不断变化,约束刚度越大,对应的压力值越大,且约束效应对低强度混凝土的作用更明显。3、分析了约束混凝土抗长杆弹侵彻机理。运用ANSYS/LS-DYNA有限元软件,对文献长杆弹侵彻混凝土靶试验进行了数值模拟,确定了合理的数值模型和参数;变化撞击速度和钢管约束混凝土厚靶半径、钢管壁厚,深入分析了钢管约束混凝土抗长杆弹侵彻机理。结果表明,提高约束刚度可有效减小侵彻深度,但是当钢管壁厚或靶径大到一定程度时,约束刚度对侵彻深度影响不大。另外,在隧道侵彻阶段,侵彻阻力基本为常数,且与撞击速度关系并不密切。4、分别建立了硬芯枪弹和刚性长杆弹侵彻约束混凝土工程模型。将约束混凝土空腔膨胀理论解应用于硬芯枪弹侵彻约束混凝土厚靶,得到了硬芯枪弹侵彻深度预测公式。基于长杆弹侵彻约束混凝土靶的数值模拟,建立了刚性长杆弹侵彻有限直径约束混凝土厚靶侵彻深度公式,公式计算侵深与数值模拟值吻合较好。
[Abstract]:As the most widely used building material in military and civil engineering, it is of great significance to study the penetration resistance of concrete. The penetration resistance of confined concrete is better than that of unconfined concrete. However, there are few researches on the anti-penetration performance and mechanism of confined concrete. In this paper, based on the existing concrete penetration test, the problem of rigid projectile penetrating the confined concrete thick target is studied by combining theoretical analysis and numerical simulation, which provides a theoretical support for the application of confined concrete in the projectile structure. It has important theoretical significance and application value. The main contents of this paper are as follows: 1. A rigid projectile penetrating semi-infinite concrete target engineering model is proposed. In view of the limitation of Mohr-Coulomb yield criterion and Griffith criterion, a cavity expansion model of concrete in comminuted area using Hoek-Brown criterion is proposed. The analytical solution of static resistance is obtained, and a new engineering model of penetration depth of semi-infinite concrete is established. The comparison with the typical penetration test and penetration depth formula shows that the spherical cavity formula proposed in this paper based on Hoek-Brown criterion has better universality and has more theoretical advantages. 2. The expansion theory of quasi-static cylindrical and spherical cavity for confined concrete is established. Based on the finite diameter model with radial elastic constraints and the Hoek-Brown criterion, the analytical solutions of quasi-static expansion of confined concrete cylindrical and spherical cavities are obtained. The results show that the expansion process of confined concrete is different from that of semi-infinite concrete medium, and the wall pressure of the cavity is constantly changing during the expansion process, and the constraint stiffness is greater. The higher the corresponding pressure value, the more obvious the effect of constraint effect on low strength concrete. 3. The mechanism of resisting long rod projectile penetration of confined concrete is analyzed. By using ANSYS/LS-DYNA finite element software, the numerical simulation of long rod projectile penetrating concrete target is carried out, and the reasonable numerical model and parameters are determined. The mechanism of resisting long rod projectile penetration of steel tube confined concrete is deeply analyzed by changing the impact velocity, the thick target radius of concrete confined by steel tube and the wall thickness of steel tube. The results show that the penetration depth can be reduced effectively by increasing the restrained stiffness, but when the wall thickness of the steel pipe or the target diameter is large to a certain extent, the constraint stiffness has little effect on the penetration depth. In addition, in the tunnel penetration stage, the penetration resistance is basically constant and does not have a close relationship with the impact velocity. 4. The engineering models of the hard core projectile and the rigid long rod projectile penetrating the confined concrete are established respectively. In this paper, the expansion theory of confined concrete cavity is applied to the penetration of hard core projectile into confined concrete thick target, and the prediction formula of penetration depth of hard core projectile is obtained. Based on the numerical simulation of long rod projectile penetrating confined concrete target, the penetration depth formula of rigid long rod projectile penetrating finite diameter confined concrete thick target is established. The calculated penetration depth is in good agreement with the numerical simulation value.
【学位授予单位】：国防科学技术大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528

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