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1.
Underwater Explosion Treatment of Marine Soft Foundation 总被引：11，自引：0，他引：11
Zheng Zhemin Yang Zhengsheng Jin Liu
Professor Academician of Chinese Academy of Sciences Director of Mechanics Institute of Chinese Academy of Sciences Beijing
Professor Mechanics Institute of Chinese Academy of Sciences Beijing Senior Engineer Lianyungang Harbor Construction Command Post Lianyungang Province of Jiangsu 《中国海洋工程》1991,(2)
The consolidation of soft foundation is a problem that commonly appears in harbor construction engineering on muddy coast. Introduced in this paper is the experimental study on underwater explosion treatment of soft foundation, including the regulations of explosion hollow development and medium movement, the law of similarity of densification and settlement of filled stone mass by shock wave pressure and explosion energy and their construction technologies, etc. A number of projects have been completed by applying this new technique, and the technique itself has been proved practicable. 相似文献
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It is well known that the accuracy of mesh-based numerical simulations of underwater explosion strongly relies on the mesh size adopted in the analyses. Although a numerical analysis of underwater explosion can be performed with enough accuracy by using considerably fine meshes, such fine meshes may lead to substantially increase in the CPU time and the usage of computer memory. Thus, how to determine a suitable mesh size in numerical simulations is always a problem confronted when attempting to study the shock wave propagation resulting from underwater explosion and the subsequent response of structures. Considering that there is currently no universally accepted method for resolving this problem, this paper aims to propose a simple method to determine the mesh size for numerical simulations of near field underwater explosion. To this end, the mesh size effects on the shock wave propagation of underwater explosion are carefully investigated for different charge weights, through which the correlation between mesh sizes and charge weights is identified. Based on the numerical study, a dimensionless variable (λ), defined as the ratio of the radius of charge to the side length of element, is introduced to be the criterion for determining the mesh size in simulations. It is interesting to note that the presented method is suitable for various charge weights. By using the proposed meshing rule, adequate balance between solution accuracy and computational efficiency can be achieved for different blast scenarios in numerical simulations of underwater explosion. 相似文献
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A-man Zhang Ling-yu Zeng Xiao-da Cheng Shi-ping Wang Yu Chen 《Applied Ocean Research》2011,33(4):240-251
Whipping response will happen when a ship is subjected to underwater explosion bubble load. In that condition, the hull would be broken, and even the survivability will be completely lost. A calculation method on the dynamic bending moment of bubble has been put forward in this paper to evaluate the impact of underwater explosion bubble load on the longitudinal strength of surface ships. Meanwhile the prediction equation of bubble dynamic bending moment has been concluded with the results of numerical simulation. With wave effect taken into consideration, the evaluation method of the total damage of a ship has been established. The precision of this evaluation method has been proved through the comparison with calculation results. In order to verify the validity of the calculation results, experimental data of real ship explosion is applied. Prediction equation and evaluation method proposed in this paper are to be used in ship structure design, especially in the preliminary prediction of the ultimate withstanding capability of underwater explosion damage for the integrated ship in preliminary design phase. 相似文献
4.
Wen-Hao Lai 《Ocean Engineering》2007,34(5-6):653-664
This investigation applies the time domain FEM/DAA coupling procedure to predict the transient dynamic response of submerged sphere shell with an opening subjected to underwater explosions. The elastic–plastic material behavior of the transient fluid–structure interaction relate to structural response equation also presented herein. This analysis also examines the transient responses of structures to different charge distances. The effects of standoff distance on pressure time history of the shell to underwater explosion (3001b TNT) are presented. Additionally, the transient dynamic responses to underwater explosion shockwaves in the sea and the air are compared. 相似文献
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通过综合分析工程建设区域的自然条件和地质条件,对比选取塑料排水板排水固结法加固护岸工程的水下软土地基。系统介绍了塑料排水板的加固机理、排水板的选型、施工工艺、质量控制要点。经过对处理后地基的沉降、位移的长期跟踪观测,结果表明:采用排水板排水加固水下软土地基,取得了理想效果,具有一定的工程指导意义。 相似文献
6.
Application of the ALE technique for underwater explosion analysis of a submarine liquefied oxygen tank 总被引：1，自引：0，他引：1
The design of submarines has continually evolved to improve survivability. Explosions may induce local damage as well as global collapse to a submarine. Therefore, it is important to realistically estimate the possible damage conditions due to underwater explosions in the design stage. The present study applied the Arbitrary Lagrangian–Eulerian (ALE) technique, a fluid–structure interaction approach, to simulate an underwater explosion and investigate the survival capability of a damaged submarine liquefied oxygen tank. The Lagrangian–Eulerian coupling algorithm, the equations of state for explosives and seawater, and the simple calculation method for explosive loading were also reviewed. It is shown that underwater explosion analysis using the ALE technique can accurately evaluate structural damage after attack. This procedure could be applied quantitatively to real structural design. 相似文献
7.
采用LS-DYNA软件,对装药半径为0.15m、0.42m、0.55m的战斗部有、无壳体的爆炸特性进行数值模拟研究,分析了炸药在有无壳体的水下爆炸时的冲击波压力、气泡脉动压力等特性参数,对比总结了不同当量、不同装药半径及有无壳体的数值计算结果。结果表明:壳体对水下爆炸气泡脉动的影响是较为显著的。壳体厚度对气泡形成时间没有太多影响,但对气泡压力峰值影响较大。因此,研究战斗部水下爆炸威力时必须考虑壳体因素,不能简化。 相似文献
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Soft marine clay deposits pose several foundation problems and such weak clay deposits have been found both along seacoasts and in offshore areas spread over many parts of the world. We suggest using some chemical injection techniques to improve the engineering behaviour of soft underwater marine clays. A test programme was carried out by injecting lime into a soft marine clay in a test tank. The penetration of lime into the soil was established by taking a number of pH measurements and calcium oxide estimation from samples taken at various radial distances. The improvement in the plasticity characteristics of the soil has been verified by indices tests. Test results indicated the improvement in the strength and reduction in the compressibility of the soil with time. The beneficial changes that occurred in the soil have been attributed to the formation of cementation compounds and these compounds have been identified by using X-ray Diffraction Technique (XRD). The test results show good promise for the use of lime grouting in the treatment of weak marine clayey deposits. 相似文献
10.
不同软基处理方法适用性比较 总被引：8，自引：0，他引：8
总结分析了国内外现有的软土地基处理的各种方法。通过对采用不同方法进行软基处理的工程实例处理效果的定量对比，发现不同软基处理方法的适用性差异很大，多数工程中仅用一种方法很难达到设计要求，而两种或多种方法联合则可望取得更好的效果。 相似文献
11.
研究自主水下航行器系统的软变结构控制策略问题。首先分析软变结构控制系统的结构特征,利用双曲正切函数,给出控制受限情形的软变结构控制策略。其次利用Lyapunov稳定性理论,讨论自主水下航行器软变结构控制系统的稳定性,然后构造了基于双曲正切函数的软变结构控制器,给出自主水下航行器软变结构控制的具体算法。基于双曲正切函数的自主水下航行器软变结构控制系统调节精度高,响应速度快,有效地削弱了系统抖振。最后通过一个仿真实验,比较了自主水下航行器垂直深度通道的4种控制策略对系统性能的影响,从而验证了研究方法的有效性。 相似文献
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青岛市中港东区码头工程水下爆岩工程量１．３万m^3,施工中采用了多段微差爆破,毫秒延迟爆破,导爆管起爆等多项为先进和成熟的施工技术,合理的施工组织,完善的施工管理,保证了工程质量,加快了工程进度。 相似文献
14.
环肋圆柱壳体在水下冲击波作用下的动力弹塑性屈曲 总被引：1，自引：0，他引：1
本文以加肋圆柱壳体为对象建立力学模型，在水下爆炸产生的冲击波作用下，考虑流体与结构的耦合效应，研究加肋圆柱壳体的弹塑性失稳变形量及动力响应特性。数值分析显示出的最终变形形状和压力变化过程与实验资料一致的 相似文献
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本文阐述了海洋工程水下软土地基加固处理的实用方法:振冲法、真空预压法、高压旋喷法、爆破法、土工织物法、强夯法以及水泥石灰系拌和法.并对这些方法的施工研究及注意问题进行了专题详述. 相似文献
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In combat operations, a warship can be subjected to air blast and underwater shock loading, which if detonated close to the ship can damage the vessel form a dished for hull plating or more serious holing of the hull. This investigation develops a procedure which couples the nonlinear finite element method with doubly asymptotic approximation method, and which considers the effects of transient dynamic, geometrical nonlinear, elastoplastic material behavior and fluid–structure interaction. This work addresses the problem of transient responses of a 2000-ton patrol-boat subjected to an underwater explosion. The KSF=0.8 is adopted to describe the shock severity. Additionally, the shock loading history along keel, the acceleration, velocity and displacement time histories are presented. Furthermore, the study elucidates the plastic zone spread phenomena and deformed diagram of the ship. Information on transient responses of the ship to underwater shock is useful in designing ship hulls so as to enhance their resistance to underwater shock damage. 相似文献
19.
AbstractBlast response of submerged pipelines has been a research focus in recent years. In this article, a three-dimensional numerical model is established to investigate dynamic response of pipelines due to underwater explosion. The u–p approximation is integrated into finite element method (FEM) to simulate pore water effect in the seabed. Numerical continuity between hydraulic pressure in the flow field and pore pressure in the marine sediment is guaranteed to realize the blast response of submerged pipelines in ocean environment. Both fluid–structure interaction (FSI) and pipeline–seabed interaction (PSI) have been considered in the proposed model simultaneously. A comprehensive parametric study is carried out after validation of the present model with test data from underground explosion and underwater explosion, respectively. The effect of embedment depth, TNT equivalent, stand-off distance, pipeline diameter, and pipeline thickness to blast response of the submerged pipelines is investigated based on numerical results. Variation of deformation patterns and stress distribution of the pipeline with various installation and structure parameters has been illustrated and discussed to facilitate engineering practice. 相似文献
20.
针对水下武器装备抗爆试验中等效药包试验缺乏明确实施规范和标准的问题,从常用的经验公式出发,通过分析计算和实例,对冲击波超压等效和冲击因子等效方法进行了比对。 其中冲击因子等效方法考虑到了药包质量、爆距、爆炸与目标相对位置和姿态等因素,以等效试验结论的合理性和贴近实际程度为依据,以实际试验为例对等效试验实施进行了分析,建议等效试验爆源药量选择15 ~ 20 kgTNT 当量为宜。 相似文献