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1.
FENG Jinji XIE Qingliang ZHAO Dayong 《天津大学学报(英文版)》2006,12(B09):228-232
When hitting underground structures directly or exploding in rock-soil media near underground structures, the conventional weapons with large charge weight will make underground structures be subjected to strong shock vibration and cause personal casualty and damage of precision electronic equipments, The shock vibration has become one of the cardinal killing means of weapons. However, the existing methods of predicting structure shock vibration are limited evidently. In this paper the coupling coefficient of acceleration in clayey soil is obtained firstly. Subsequently based on repeated experiments of chemical explosion, after dimension analysis and by using method of multivariate stepwise regression, the calculation formulae of shock vibration acceleration for the underground structure are obtained finally. The formulae consider top and side explosion respectively, taking into account the effects of penetration depth, charge weight, distance to explosion center, rock-soil media, size of structure and buried depth. They are easy to use with high practicability and degree of confidence, and can provide credible evidence for prediction of shock vibration and vibration isolating design of underground structure. 相似文献
2.
Test and Analysis of an Existing Tunnel Vibration Induced by Blasting Construction of Diaphragm Wall
YU Guangxi YU Haitao LIU Xian YUAN Yong WANG Qingguo CHENG Guorong WU Xiaofeng 《天津大学学报(英文版)》2008,14(1)
According to the blasting construction of the diaphragm wall of Puxi approaching section of East Fuxing Road river-crossing tunnel,the monitoring project of the vibration of the existing tunnel induced by the blasting construction is put forward,which includes the sensors' location,monitor method and the vibration monitoring system.Based on the monitoring data of the explosion vibration,the vibration wave forms,velocities,acceleration responses,main frequencies and fields of measure points are analyzed under the conditions of three locations and different charge quantities.According to the safety-judging standard of explosion vibration,the conclusion that the existing tunnel is safe under the explosion vibration is then drawn.Furthermore,the spectrum characteristics of three explosion vibrations and the spectrum changing properties of explosion vibration wave transmitting in different directions are concluded,which can provide reference to similar projects. 相似文献
3.
In order to improve the present aviation ejection escape system, the application of explosion cutting technique to aviation escape system is proposed to weaken the strength of canopy before ejecting it. A series of mini cutting explosives are designed to investigate the process of splitting PMMA plate. The phenomenon of spallation in PMMA is observed. The effects of different parameters of mini cutting explosives on the cutting depth are obtained. Consequently the appropriate material of half-circular metal covers, explosive types and the ranges of charge quantities are determined. On the other hand, the cutting process of aviation PMMA plate by mini cutting explosives is simulated by means of nonlinear dynamic analysis code LS-DYNA. In finite element analysis,Arbitrary Lagrangian Euler (ALE) algorithm is used to depict the fluid property of high energy explosives. Continuous damage material model is used to simulate the complicate dynamic damage behavior of PMMA due to explosion shock waves. Only sliding contact option is defined to fulfill the fluid-structure interaction between explosives and PMMA plate by distributed parameter methods. Phenomenon of spallation observed in the experiment is presented in the simulation. The relationship between the penetration depth of PMMA plate and charge linear density obtained by numerical simulation agrees well with experimental result. 相似文献
4.
Simulation of Airblast Load and Its Effect on RC Structures 总被引：1，自引：0，他引：1
In the analysis of a structure subjected to an explosion event, the determination of the blast load constitutes a crucial step. The effect of the blast load on the structure depends not only on the peak shock overpressure, but also the impulse (hence the duration). For structures with a regular geometry, the blast load may be fairly well estimated using appropriate empirical formulae; however, for more complex situations, a direct simulation using appropriate computational techniques is necessary. This paper presents a numerical simulation study on the prediction of the blast load in free air using a hydrocode, with focus on the sensitivity of the simulated blast load to the mesh grid size. The simulation results are compared with empirical predictions. It is found that the simulated blast load is sensitive to the mesh size, especially in the close-in range, and with a practically affordable mesh grid density, the blast load tends to be systematically underestimated. The study is extended to internal blast cases. An example concrete slab under internal explosion is analyzed using a coupled analysis scheme. The internal blast load from the simulation is examined and the response of the RC slab is commented. 相似文献
5.
利用QLVC-ZSA1振动信号分析仪及加速度传感器,对数控车床在不同切削要素的车削过程中刀具的振动响应进行了测试及量化研究,得到了刀具振动加速度信号的时域曲线及自功率谱密度曲线。研究表明:刀具的振动响应是一个随车削进行的时变过程,在同一走刀相同车削要素的车削过程中,随着去除材料的增加,刀具所受的激振能量减少;随着切削深度的增加,刀具振动的最大自功率谱密度并非单调增加,车削深度对于刀具振动的影响存在一个临界值;随着主轴转速及进给速度的提高,刀具振动的自谱密度值随之增大,而相应的振动频率降低。 相似文献
6.
对国内外城市地下线形结构（地下管道、地下铁道和隧道等）震害的形式、成因及外部影响因素，如地震烈度、场地土条件、埋深、结构构造特点及尺寸等进行了综合分析．并就不同地下线形结构抗震措施的制订发表了见解。综合有关文献资料和工程实例．对盾构隧道进行纵向抗震分析，总结了地震区隧道结构的震害特点以及目前所采用的抗震措施，以供地震区隧道结构的设计、施工、加固作参考。 相似文献
7.
This paper presents the explosion cratering effects and their propagation laws of blast waves in dry standard sands using
a 450 g-t geotechnical centrifuge apparatus. Ten centrifuge model tests were completed with various ranges of explosive mass, burial
depth and centrifuge accelerations. Eleven accelerometers were installed to record the acceleration response in sand. The
dimensions of the explosion craters were measured after the tests. The results demonstrated that the relationship between
the dimensionless parameters of cratering efficiency and gravity scaled yield is a power regression function. Three specific
function equations were obtained. The results are in general agreement with those obtained by other studies. A scaling law
based on the combination of the π terms was used to fit the results of the ten model tests with a correlation coefficient of 0.931. The relationship can be
conveniently used to predict the cratering effects in sand. The results also showed that the peak acceleration is a power
increasing function of the acceleration level. An empirical exponent relation between the proportional peak acceleration and
distance is proposed. The propagation velocity of blast waves is found to be ranged between 200 and 714 m/s. 相似文献
8.
Experimental Studies on High-Frequency Performance of the Inverse Control Magneto-Rheological Damper
Severe vibration of underground structures may be induced under blast loads. According to the characteristics of the explosion-induced ground shock wave, a new-type damper, inverse control magneto-rheological(MR) damper was designed to control the vibration. The high-frequency performance test of the MR damper was carried out on the small shaking table. It is shown that the performance can be modeled by use of the modified Bouc-Wen model, and the parameters of the model keep stable in the ranqe of 15-50 Hz. 相似文献
9.
高原地区进行的水下爆破工程,因水体表面气压随海拔的升高而线性降低,其装药爆炸后的特征参数是否发生变化,对爆破施工有重要意义;采用密闭的高压爆炸容器,模拟高原气压条件,对雷管水下爆炸参数进行了实验研究,研究结果表明：在海拔0---4500m范围内随着气压降低,冲击波峰值压力大小与气压无关。冲击波衰减时间却有一定增长,导致比冲击波能微小增大;气泡脉动周期按二阶多项式规律显著增大,仍由于气压随海拔升高丽变小,装药深度处的总静水压力随之降低,使比气泡能微量减小,而爆炸总能量基本不变。 相似文献
10.
Plane charge explosion technique (PCET) is one of the major techniques frequently used in large-scale blast-resistant structure tests. An FEM model was established, which can simulate the process of air releasing from the blast cavity. The effects of the charge density, the interval of the charge strip, the distance of the charges from the structure, and the mass of backfill soil on the overpressures applied on the tested structures were analyzed by the FEM model. The quantitative relationships between the peak value and the duration of the overpressure and the above-mentioned affecting parameters were established. Agreement between numerical results and the test data was obtained. 相似文献
11.
通过对掏槽爆破的实验研究,利用火药和猛炸药的联合装药方式,改变了以往的单一装药结构．模拟实验的结果表明,联合协同装药结构与单一装药结构的掏槽效果有着显著的区别．前者的掏槽效果要优于后者;同时通过炸药水下的测试结果表明,改进以后的装药结构的冲击波峰值压力的持续时间明显提高,即联合装药的爆炸生成气体量要大于单一装药,为爆破工程上快速高效的掘进提供了理论依据。 相似文献
12.
This paper studies the influence of radial depth on vibration, chip formation and surface roughness during face milling of AISI304 austenitic stainless steel with indexable cemented carbide milling cutters. The amplitude of vibration acceleration increased with the increasing radial depth up to 80 mm. And the domain vibration frequency varied with the radial depth. In this paper, three types of chips were found: C shape, long shape and spiral shape. The minimum surface roughness value occurred when the radial depth equalled 40 mm in the experiment. Irregular changes of chip curl radius and chip thickness could be attributed to different numbers of alternately engaged teeth when the feed and speed were fixed. Surface roughness is related to forced vibration and chip formation. Radial depth with different numbers of alternately engaged teeth could significantly influence the forced vibration, chip formation, and surface roughness. 相似文献
13.
A simplified method is proposed for analyzing the overpressure history of an optional point on the walls of a closed cuboid due to its internal optional point-explosion. Firstly, the overpressure histories of all nodes on the walls of a cube with a side-length of 2 m are computed under a reference-charge explosion at each node of its inner space using the LS-DYNA software, and then are collected to form a reference database. Next, with the thought of the isoparametric finite element, an interpolating algori... 相似文献
14.
方小兵 《五邑大学学报(社会科学版)》1992,(1)
本文采用矩阵传递法分析了调频质量阻尼器(TMD)被动控制高层建筑风振反应,导出了结构顶层位移、加速度和基底剪力频域内统计特征公式。最后通过实例的结果说明,经过控制后能显著地降低风振反应。 相似文献
15.
凌静秀杨晓静吴志鸿詹友基 《福建工程学院学报》2019,(6):560-564
结合现有传统鞋底方案及多胞结构特征,设计了菱形和正六边形两种多胞结构的鞋底方案,并用有限元法对不同鞋底的静力学性能进行分析,得出最优的鞋底结构方案。结果表明,同一工况下正六边形多胞鞋底结构平均变形量最大,减振缓冲性能最优越。同时,对正六边形多胞尺寸参数进行影响分析,得出当正六边形边长5mm,凹槽深度为2.5mm时,鞋底结构具有最佳的缓冲性能。 相似文献
16.
Numerical Simulation of Dynamic Response and Collapse for Steel Frame Structures Subjected to Blast Load 总被引：4，自引：0，他引：4
The progressive collapse of steel frame structures under the blast load was investigated using LS-DYNA. The multi-material Eulerian and Lagrangian coupling algorithm was adopted. A flu-id-structure coupling finite element model was established which consists of Lagrange element for simulating steel frame structures and concrete ground, multiple ALE element for simulating air and TNT explosive material. Numerical simulations of the blast pressure wave propagation, struc-tural dynamic responses and deformation, and progressive collapse of a five-story steel frame structure in the event of an explosion near above ground were performed. The numerical analysis showed that the Lagrangian and Eulerian coupling algorithm gave good simulations of the shock wave propagation in the mediums and blast load effects on the structure. The columns subjected to blast load may collapse by shear yielding rather than by flexural deformation. The columns and joints of steel beam to column in the front steel frame structure generated enormous plastic defor-mation subjected to intensive blast waves, and columns lost carrying capacity, subsequently lead-ing to the collapse of the whole structure. The approach coupling influence between struc-tural deformation and fluid load well simulated the progressive collapse process of structures, and provided an effective tool for analyzing the collapse mechanism of the steel frame structure under blast load. 相似文献
17.
The progressive collapse of steel frame structures under the blast load was investigated using LS-DYNA.The multi-material Eulerian and Lagrangian coupling algorithm was adopted.A fluid-structure coupling finite element model was established which consists of Lagrange element for simulating steel frame structures and concrete ground,multiple ALE element for simulating air and TNT explosive material.Numerical simulations of the blast pressure wave propagation,structural dynamic responses and deformation,and progressive collapse of a five-story steel frame structure in the event of an explosion near above ground were performed.The numerical analysis showed that the Lagrangian and Eulerian coupling algorithm gave good simulations of the shock wave propagation in the mediums and blast load effects on the structure.The columns subjected to blast load may collapse by shear yielding rather than by flexural deformation.The columns and joints of steel beam to column in the front steel frame structure generated enormous plastic deformation subjected to intensive blast waves,and columns lost carrying capacity,subsequently leading to the collapse of the whole structure.The approach coupling influence between structural deformation and fluid load well simulated the progressive collapse process of structures,and provided an effective tool for analyzing the collapse mechanism of the steel frame structure under blast load. 相似文献
18.
Dynamic Responses Analysis of a Building Structure Subjected to Ground Shock from a Tunnel Explosion
Dynamic responses of a multi-storey building without or with a sliding base-isolation device for ground shock induced by an in-tunnel explosion are numerically analyzed. The effect of an adjacent tunnel in between the building and the explosion tunnel, which affects ground shock propagation , is considered in the analysis. Different modeling methods, such as the eight-node equal-parametric finite element and mass-lumped system, are used to establish the coupling model consisting of the two adjacent tunnels, the surrounding soil medium with the Lysmer viscous boundary condition, and the multi-storey building with or without the sliding base-isolation device. In numerical calculations , a continuous friction model, which is different from the traditional Coulomb friction model, is adopted to improve the computational efficiency and reduce the accumulated errors. Some example analyses are subsequently performed to study the response characteristics of the building and the sliding base-isolation device to ground shock. The effect of the adjacent tunnel in between the building and the explosion tunnel on the ground shock wave propagation is also investigated. The final conclusions based on the numerical results will provide some guidance in engineering practice. 相似文献
19.
采用有限元方法对K5206NM压缩机机体进行了模态分析和振动响应分析,不仅获得了机体的固有频率和振型,还得出机体在动态工况下的位移、应力、速度及加速度变形云图,找到了机体结构的薄弱环节,并提出了相应的改进方案,为机体的结构设计改进提供理论依据. 相似文献
20.
运用变分法研究了傍轴超高斯型光束在强非局域非线性介质中的传输特性,得到了傍轴超高斯型光束各参量的近似演化方程、一个势函数以及一个临界功率;求出了傍轴超高斯型光束各参量的近似演化表达式;并通过分析得到当初始功率等于临界功率时,可以获得稳定的超高斯型空间光孤子;对于一般情形,傍轴超高斯型光束束宽则作周期性的压缩或展宽变化. 相似文献