埋地输油管道对爆破振动的动力响应

为了控制爆破振动对油气管道的影响,利用ANSYS/LS-DYNA软件对埋地管道在爆破作用下不同方向的受力过程进行数值模拟,建立埋地管道三维有限元模型,采用多物质流固耦合算法模拟爆破过程。结果表明:基于流固耦合方法模拟得到的振速与现场实测结果基本一致,利用该模拟方法研究爆破振动对埋地输油管道的影响是可行的。经过爆破模拟分析,得到埋地管道上的有效应力变化规律。迎爆面和背爆面受到的应力远高于管顶、管底受到的应力,且迎爆面的有效应力大于背爆面,说明迎爆面是最容易发生变形的;管顶和管底位于管道的中轴面上,受到的应力较小,变形也较小。     

水下爆炸载荷作用下加肋圆柱壳应变响应研究

采用加肋圆柱壳结构模型模拟潜艇结构,对其在水下爆炸冲击载荷作用下的响应过程进行试验研究。结果表明:采用应变测量的方法对结构进行模态分析是可行的;受附连水质量的影响,加肋圆柱壳结构的低阶湿模态频率较干模态频率显著下降;在爆炸载荷作用下,距离爆炸点越近结构承受的冲击作用越严重,越容易产生塑性破坏;应变的最大响应是冲击波载荷和一次脉动压力载荷共同作用的结果,第二次脉动压力对结构的动态应变响应贡献不明显。     

爆破荷载作用下埋地钢管的动态响应实验研究

爆破荷载作用下埋地管道的动态响应问题是城市爆破施工中亟需解决的课题之一,具有重要的理论和现实意义。在理论分析的基础上,通过改变药量、爆心距、管道内压以及爆源埋深中某一参数对埋地无缝钢管进行现场爆破实验,其中药量为50~200 g,每次实验改变25 g共七次;爆心距分别为2.2 m、2.7 m和3.2 m;管道内压分别为0 MPa、0.2 MPa、0.4 MPa和0.6 MPa;爆源埋深分别为0.5 m、1 m、1.5 m和2 m。结果表明:在正常工作压力下钢管内径和管壁厚度的比值越大,管道容许压缩应变值越小;管道应变与比例距离成反比,随着比例距离增大,应变减小;并得出了在实验条件下的应变峰值与爆心距和药量计算公式。     

不同爆炸荷载下长江隧道的动力响应和损伤分析

运用ANSYS/LS-DYNA有限元软件,对长江隧道中的非接触空中爆炸和接触爆炸等2种工况进行数值模拟分析,研究2种爆炸工况中盾构隧道衬砌结构内的能量耗散特性,基于能量原理探讨盾构隧道中衬砌结构各部位的动力响应,明确不同工况中隧道内爆炸冲击波的传播过程,获得隧道行车道板和衬砌结构的损伤特征,研究结果为大型盾构隧道抗爆设计提供理论依据.     

爆炸冲击下变截面H型钢动态响应模拟研究

钢结构在爆炸冲击下的动态响应是一个复杂的动力学问题。运用ABAQUS软件,建立两端固定约束下变截面H型钢构件模型,利用CONWEP爆炸加载方式,模拟3~8.25 m八种不同爆炸距离下钢构件的动态响应过程,分析结构腹板、迎爆面翼缘变形与爆炸距离的关系。结果表明:CONWEP程序能够准确的作为爆炸加载方式;在3~6.75 m爆炸距离内,腹板发生塑性变形,随着爆炸距离的增加,构件腹板最大位移线性减小,最大位移位置非线性升高;翼缘最大位移迅速减小,翼缘发生失稳破坏;在6.75~7.5 m爆炸距离内,腹板处于弹塑性变形阶段;当爆炸距离超过7.5 m后,腹板处于弹性变形阶段,迎爆面翼缘发生局部失稳,承载力降低。     

Mechanical Properties of the Buried Pipeline Under Impact Load Caused by Adjacent Heavy Tamping Construction

Journal of Failure Analysis and Prevention - Impact load caused by adjacent heavy tamping construction has a significant effect on mechanical properties of the buried pipeline. Based on nonlinearly...     

下穿隧道爆破地震作用下埋地输气管道的动力响应规律研究

以下穿兰成渝输气管道的西安至成都客运专线仙女岩隧道爆破为背景,根据现场实测振动数据,采用LS-DYNA3D方法和掏槽孔爆破的等效药包原理,建立能反映输气管道与其周围土体相互作用的三维动力有限元模型,分析爆破地震波引起的埋地输气管道的动力响应规律,包括不同隧道埋深、管道直径与管道壁厚对管道振动特征及其响应动应力的影响规律。研究结果表明:爆破地震作用将引起埋地输气管道下部压缩、上部拉伸的动力响应;在隧道埋深20 m、掏槽孔总药量为14.4 kg同时起爆的条件下,直径512 mm、壁厚8 mm输气管道的最大轴向压应力和最大轴向拉应力分别是9.57 MPa和7.76 MPa,仅为管道屈服强度的1.99%和1.61%,相应的管道地表振速为15.28 cm/s;爆破地震作用引起的输气管道动应力随着隧道埋深的增加而显著降低,而管道直径的增加或壁厚减小都会引起管道动应力增大;管道上方地表土体的振动速度随着管径的增大而减小,管壁厚度对管道和土体的质点振动速度基本没有影响。     

浅埋连拱隧道爆破的数值模拟

运用ANSYS/LSDYNA软件,建立三维隧道整体模型,考虑自重应力,选取不同的围岩级别、不同的炸药当量等6种工况,分别计算后行洞掌子面爆破的浅埋连拱隧道速度场分布和应力场分布,得出最大震速和最大主应力峰值沿横向和纵向分布规律,分析爆破对先行洞隧道仰拱和中隔墙的影响,得出围岩级别和炸药当量与震速峰值和最大主应力峰值之间的基本关系,对确定先行洞二衬施做时机、浅理连拱隧道工程实践具有一定的参考价值.     

Mechanical Response and Energy Dissipation Analysis of Heat-Treated Granite Under Repeated Impact Loading

The mechanical behaviors and energy dissipation characteristics of heat-treated granite were investigated under repeated impact loading. The granite samples were firstly heat-treated at the temperature of 20°C, 200°C, 400°C, and 600°C, respectively. The thermal damage characteristics of these samples were then observed and measured before impact tests. Dynamic impact compression tests finally were carried out using a modified split-Hopkinson pressure bar under three impact velocities of 12 m/s, 15 m/s, and 18 m/s. These test results show that the mineral composition and the main oxides of the granite do not change with these treatment temperatures. The number of microcracks and microvoids decreases in the sample after 200°C treatment. The mechanical properties of a sample after 600°C treatment were rapidly deteriorated under the same impact velocity. The average of peak stress is much smaller than those after 20°C, 200°C and 400°C treatments. The heat-treated samples have an energy threshold each. When the dissipated energy of a sample under a single impact is less than this threshold, the repeated impacts hardly lead to further damage accumulation even if its total breakage energy dissipation (BED) density is large. Under the same number of repeated impacts, the cumulative BED density of a sample after 600°C treatment is the largest and its damage evolves most quickly. The total BED density of the sample after 200°C treatment is the highest, which implies that this sample has better resistance to repeated impact, thus having less crack initiation and growth.     

爆炸荷载作用下礁沙地基钢塔架结构动力响应试验探究

爆炸荷载作用下礁砂地基钢塔架结构动力响应的研究,对我国的国防和岛礁工程建设具有重要的参考和现实意义.通过模型试验对不同礁砂地基类型、药量、爆心距等工况下钢塔架结构加速度动力响应信号进行测试,结合量纲分析与π定理,得到钢塔架结构模型的加速度动力响应计算公式,并利用试验所采集的数据对计算公式进行参数拟合,得出了在礁沙地基下...     

水下爆炸载荷作用下细长体圆柱壳结构鞭状响应

采用2阶DAA流固解耦技术,对水下爆炸载荷作用下细长体圆柱壳结构的鞭状响应进行分析研究。经模型试验验证后,对细长体圆柱壳梁模型随不同药包爆炸方位、不同爆距及不同低频振动频率耦合程度变化时的鞭状响应进行计算,揭示圆柱壳梁模型在水下爆炸载荷作用下的总体低频运动特性及鞭状响应规律,为研究细长体圆柱壳结构在水下爆炸载荷作用下的鞭状效应总体损伤提供试验基础及理论方法。     

控制加载爆填法处理深厚淤泥的工程应用

针对工程中深厚淤泥及工程地质条件较差的特点,采用储能药包控制加载爆填法进行软基处理,该方法既能够达到减振的效果又可以确保深厚淤泥的完整置换.该文通过实际工程中技术问题的解决、施工工艺及爆炸参数的确定,结合质量检测等方面说明了该方法可以应用于实际工程中.     

Failure Analysis of Physical Explosion due to Gas Jetting from High-Pressure Pipeline

Jetting of the combustible gas with high pressure is a prelude to bringing into action of the chemistry explosion of gas cloud. Comparing with the leakage and diffusion of combustible gas and the chemistry explosion effect of gas cloud, the distribution of pressure, temperature and velocity formed by high-pressure gas jetting after the destruction of a pipeline, has been paid less attention to in the related field. There are a few fundamental data on the subject of evaluation of physical explosion parameters. In this paper, a physical explosion case of hydrogen gas transported through a high-pressure pipeline is reported, and a cause analysis of the explosion accident is proposed. Numerical simulation yields the field state parameters and the damage characteristics in the process of high-pressure gas jetting. In front of the leakage gas flow, a shock wave forms due to high-pressure gas jetting. The physical explosion can trigger the combustion of leaked hydrogen gas. Though the pressure rapidly attenuates behind the shock wave, a relatively high velocity is maintained until the control valve in the pipeline system is closed down or the jetting finishes. In the given accident case, the shock wave pressure reaches an order of 1 MPa and the temperature reaches 200–300 °C. This temperatures is obviously less than the igniting temperature of hydrogen gas, 400 °C. But the combustion of leaked gas may be triggered by the spark caused by the impact of instrument plates. Since the instrument plates near the leaking port of pipeline has been damaged already before the leaked gas burns, the electric spark from the line short or the strike spark between metal parts are also completely possible to trigger this combustion.     

非接触爆炸冲击载荷对防盗门作用数值模拟研究

为实现反恐行动中非接触爆炸冲击波破门目标,针对金属防盗门实际条件建立数值仿真模型,重点研究了防盗门在非接触爆炸冲击载荷作用下塑性变形破坏过程及规律。结果表明：相同爆炸冲击载荷作用下,实际转动条件防盗门板塑性变形动力响应时间延长,最大变形量远大于四边固支条件下门板变形量;爆炸中心与防盗门距离过近,门板受爆炸产物和空气冲击波共同作用,只出现局部破坏,不能实现门板整体塑性变形;拟合了防盗门板在非接触爆炸冲击载荷作用下变形量计算式,可为反恐破门弹药设计提供依据。     

分层多孔抗冲覆盖层水下爆炸响应分析

针对芯层为分层多孔泡沫的抗冲覆盖层在水下非接触爆炸冲击波作用时的响应进行了理论分析。对比了分层覆盖层与均匀覆盖层的冲击防护效果。结果表明:在同样的入射冲击波作用下,分层多孔覆盖层能有效降低覆盖层的厚度,抵抗更强的冲击波;但是,分层多孔覆盖层传递到被保护结构的应力要大于均匀覆盖层。该研究结果能为梯度覆盖层的设计提供参考。     

Response of Elliptical Composite Cylinders to Axial Compression Loading

The results from semianalytical predictions and experiments are used to study the response of composite cylinders with elliptical cross sections loaded axially to a significant percentage of their buckling load. The semianalytical approach is based on the methods of Marguerre, Rayleigh-Ritz, and Kantorovich. The radius of curvature and the displacements are approximated by expansions in harmonic series in the circumferential arc-length coordinate, and the coefficients of the displacement series are unknown functions of x which are solved for using the finite-difference method. The primary features of the predicted response are first described. Then the experiments are described and results for elliptical cylinders with varying degrees of orthotropy are compared with predictions. Where appropriate, calculations based on the analysis of circular cylinders are compared with the semianalytical calculations for the ellipse. Correlation between experiments and predictions is good, and it is demonstrated that despite the noncircular cross section, many responses of an ellipse are very similar to the axisymmetric response of circular cylinders subjected to an axial load. The similarity is independent of the degree of orthotropy of the elliptical cylinder.     

钢筋混凝土在冲击载荷下的动态力学性能

利用一级轻气炮加载,对钢筋混凝土圆柱形靶板进行冲击压缩实验,飞片与靶板同质,由预埋的锰铜压阻传感器测量出压力-时间信号曲线.实验数据采用拉氏分析方法中的路径线法自编程序进行处理,反算出粒子速度、应变等力学参量.实验结果表明:钢筋混凝土材料的应力应变总体呈滞回特性,并具有明显的应变率相关性和波形弥散效应等动态力学性能.同时基于复合材料细观力学的方法,认为理想情况下钢筋混凝土本构关系可由混凝土材料粘弹性本构关系与一个依赖于增强钢筋材料特性的常量G的乘积确定,并假定损伤只发生在混凝土内部,给出了钢筋混凝土的损伤型动态本构关系,理论预测曲线与试验结果吻合良好.     

水下爆炸载荷作用下加筋圆柱壳的响应分析

运用MSC．DYTRAN软件，首先比较了网格划分密度的改变，耦合法的选取及边界条件对计算的影响。并在合理的网格划分和耦合方法选用的基础上，设置符合实际的边界条件，在壳体的迎爆面，侧爆面和背爆面各选取一个点，在分析光壳的响应的基础上，详细计算了加筋圆柱壳对水下爆炸冲击波的响应。比较分析了不同的尺寸参数对结构抗爆性能的影响，并做了综合讨论，计算中考虑了材料的应变率强化效应。在此基础上验证了增加壳体厚度，减小加筋间距和增加加筋高度等有利于提高加筋圆柱壳抗爆性能的方法，同时得到了一个适合本例计算的较优化模型。     

爆炸荷载作用下围岩累积损伤效应的数值分析

巷道爆破开挖推进过程中,循环爆破开挖的多次扰动作用使保留岩体产生累积损伤,导致岩体力学参数的弱化,从而造成工程岩体的宏观失效。利用ANSYS/LS-DYNA的重启动技术,通过损伤云图和损伤变量D的变化,对圆形巷道循环进尺过程中爆破作用下的岩体累积损伤效应进行研究。计算结果表明:随着掌子面推进爆破次数的增加,围岩的损伤程度加深,但影响深度变化较小;在装药量和爆心距不变的情况下,损伤量与爆破次数之间有很好的非线性关系,即爆破损伤的累积具有非线性特性。     

石灰岩在爆炸载荷作用下的破坏机理试验研究

为了探讨岩石在爆炸载荷下的力学特性和破坏机理,采用耦合填塞装药、耦合无填塞装药和不耦合填塞结构模拟了爆炸应力波和爆生气体的不同加载强度,在石灰岩中进行模拟爆破试验,对爆炸应变波及其参数、以及爆破后岩石内部的声波速度进行了测试.基于模拟爆破试验结果,对石灰岩的力学特性和爆破损伤程度进行了分析,得到了岩石在不同爆破条件下的爆破损伤和破坏规律.