共查询到19条相似文献，搜索用时 125 毫秒
1.
海洋地震频繁且海底土体环境复杂，当地震导致断层土体发生永久变形后，穿越断层的海底埋地管道也将受迫发生变形。为确定变形后的管道能否正常工作，需根据实际工况对其进行应变响应预测。首先通过有限元计算软件ABAQUS建立管道与走滑断层的三维实体模型，模拟管-土间的接触作用并通过等效边界方法修正模型，得到管道局部屈曲破坏形式及应变分布情况。然后，通过调整有限元模型参数对断层交角、管道工作内压、管道径厚比对管道极限塑性应变的影响进行敏感性分析，定性分析不同敏感性因素对穿越走滑断层海底管道应变响应的影响。最后，在数值模拟数据的基础上通过MATLAB软件利用基于遗传算法优化的BP神经网络实现对管道应变响应的精确预测。结果表明:穿越走滑断层管道在发生局部屈曲时，可根据轴向压缩应变突变现象确定管道局部屈曲时对应的断层位移，并且断层交角、管道工作内压和管道径厚比都会对跨断层管道应变响应产生影响。 相似文献
2.
基于ABAQUS软件平台，建立穿越断层的管道、有压液体及周围土体的三维有限元模型，分别在静力荷载作用和地震作用下，对不同运动形式断层（走滑断层、正断层、逆断层）中的管道进行模拟，并对管道内有无有压液体进行对比分析。分别得到管道在静力荷载作用下和地震作用下空管道与有压管道的变形特征，将其进行对比分析，得到管道内液体的质量和压力在静力荷载作用及地震荷载作用下对管道的不同影响。结果表明：在静力荷载作用下管道内液体的质量和压力提高了管道的抗变形能力，使管道更安全；而在地震作用下管道内液体的质量和压力削弱了管道的抗变形能力，使管道更容易被破坏。 相似文献
3.
双节点有限元模拟直立走滑断裂地震位移场 总被引：2，自引：0，他引：2
结合位错理论和有限单元法，对介质横向不均匀性引起的直立走滑断裂地震水平位移场不对称性进行了数值模拟研究。结果表明，断层两侧介质泊松比和弹性模量的横向不均匀性，均可以引起直立走滑断层同震破裂及地震位移场的不对称性，其中，断层两侧介质的剪切模量比(刚度比)对直立走滑断裂地震位移场不对称性起主要作用。 相似文献
4.
埋地管道地震作用下的破坏因素源于地震引起的永久地面变形(PGD),其中管道-土体间相互作用决定土体位移作用到管体的大小。利用离心机试验技术模拟埋地管道在逆断层大位移下的反应特性,重点讨论断层与管道的交角、断层位移大小、管土相互作用、管径和埋深五个参数对管道破坏的影响水平。实验结果表明:上述参数对管道断层作用的反应均有明显影响,其中断层的位移量、管土相互作用、埋深和管径的影响更为显著。本文的研究结果对于管道经过断层区的抗震设计有十分重要的意义。 相似文献
5.
利用新疆独山子台跨断层形变观测资料,对独山子山前断层的活动速率、活动特征及区域应力场进行了分析,结合震源机制解的研究成果进行了对比验证,同时应用"速率累加"分析方法进行了异常提取.结果显示:①独山子一安集海断裂垂直位移年平均变化量为0.106 mm,沿基线方向的水平位移年平均变化量为0.189 mm,沿断层走向的水平走滑年平均变化量为-0.883 mm,断层活动以右旋走滑为主兼具逆冲分量;②1993～2007年独山子断层的最大水平主压应力方向在339.85°～346.78°之间,平均为344.23°;③乌苏5.1级地震前,独山子台的形变记录曲线有较明显的速率异常变化与同震形变波动. 相似文献
6.
利用西藏地震台网记录到的2017年11月18日西藏米林6.9级地震及其余震序列资料,研究此次地震的发震机制断层。双差定位结果显示,余震沿着主震的NW和SE方向往两侧扩展分布,震源深度主要集中在2～12 km,同时从短轴剖面上地震分布推断,此次米林地震的发震断层倾角约为45°。对ML3.5以上的余震采用CAP方法进行波形拟合震源机制反演,其结果显示,此次米林地震序列震源错动类型以逆冲和走滑为主,比较符合该区域的构造动力环境。应力场反演结果显示,米林地震序列主压应力轴（S1轴）方向为NNE-NS向,主张应力轴（S3轴）方向为SEE-SE向;反映的断层错动方式为逆冲兼走滑类型。地震余震序列展布以及震源机制分布显示断层走向和断层特性与帕隆—旁辛断裂的特征较为吻合,推测米林地震的发震断裂为帕隆—旁辛断裂。 相似文献
7.
8.
穿越逆冲断层的埋地管道非线性反应分析 总被引：2，自引：0，他引：2
穿越逆冲断层的埋地管道在地震作用下,容易发生局部屈曲或整体失稳等形式的破坏,研究逆冲断层作用下的埋地管道地震反应规律,对管道抗震设计及施工等具有重要的意义。本文将埋地管线及周围土体从半无限地球介质中取出,分别以空间薄壳单元和实体单元进行离散,采用非线性接触力学方法模拟管、土之间的滑移、分离及闭合现象;采用线性位移加载模拟断层的错动,考虑了系统初始应力状态的影响,对土体未开裂前的管土相互作用系统进行了拟静力数值分析;分析了位错量、土体刚度、埋设深度、径厚比及跨越角度对埋地管道反应的影响,得出了一些有益的结论。 相似文献
9.
2008年5月12日四川省汶川县发生了Ms8.0强烈地震.发震断层是龙门山断裂带的映秀-北川断裂.分析震前的GPS速度场发现,从巴颜喀拉块体西部到龙门山断裂带沿大约N103°E方向的缩短速率为13.0 mm/a,龙门山断裂带的右旋走滑速率1.1 mm/a,断裂带处于闭锁状态.四川盆地沿大约N103°E方向有少量的压缩变形,而沿SW方向有少量的拉张变形.同震位移场显示,这次地震可能是巴颜喀拉块体SE向逆冲与四川盆地NW向俯冲同时发生的.应变场分析发现,震前震中区的主压与主张应变率分别为-30.840×10-9/a与13.956×10-9/a,主压应变轴N105.4°E与震源机制解得到的主压应力轴的方向N103°E一致.由本文提出的应力-应变机制得到的断层滑动方向和走向与地表破裂调查和震源机制解得到的结果一致.印度、太平洋和菲律宾海板块与欧洲板块的相互作用足龙门山断裂带积累弹性应变能和孕育汶川地震的长期作用力.苏门达腊大地震使青藏高原和华南块体的相互作用加强,促进了汶川地震的发生. 相似文献
10.
通过对2008年5月12日发生的汶川8.0级地震的发震构造——中央断裂映秀—南坝段地震地表破裂、地表形变及断裂上余震迁移等特征的详细调查和分析,结果表明：（1）自映秀至南坝,断层活动方式表现为由逆冲逐渐过渡为逆冲-右旋走滑、再到走滑分量与逆冲分量大致相当,同时断层两盘滑动伴有相对弱旋转活动;（2）在断层总体走向NE向、逆冲为主兼右旋走滑活动方式下,局部表现为走向NW向、逆冲为主兼左旋走滑活动方式;（3）地震裂缝与单侧破裂面关系,以及地表重叠缩短形变特征表明,断层活动、应变能释放是在近EW向区域构造应力及NE向局部构造应力综合作用下的结果.依据断层沿线地表裂缝产状的变化,粗略推出映秀至南坝段主应力方向由SEE向NEE方向变化,与前人使用CAP（Cut and Pasate）方法求出的主余震源机制方向基本一致. 相似文献
11.
The performance of pipelines subjected to permanent strike–slip fault movement is investigated by combining detailed numerical simulations and closed-form solutions. First a closed-form solution for the force–displacement relationship of a buried pipeline subjected to tension is presented for pipelines of finite and infinite lengths. Subsequently the solution is used in the form of nonlinear springs at the two ends of the pipeline in a refined finite element model, allowing an efficient nonlinear analysis of the pipe–soil system at large strike–slip fault movements. The analysis accounts for large strains, inelastic material behavior of the pipeline and the surrounding soil, as well as contact and friction conditions on the soil–pipe interface. The numerical models consider infinite and finite length of the pipeline corresponding to various angles β between the pipeline axis and the normal to the fault plane. Using the proposed closed-form nonlinear force–displacement relationship for buried pipelines of finite and infinite length, axial strains are in excellent agreement with results obtained from detailed finite element models that employ beam elements and distributed springs along the pipeline length. Appropriate performance criteria of the steel pipeline are adopted and monitored throughout the analysis. It is shown that the end conditions of the pipeline have a significant influence on pipeline performance. For a strike–slip fault normal to the pipeline axis, local buckling occurs at relatively small fault displacements. As the angle between the fault normal and the pipeline axis increases, local buckling can be avoided due to longitudinal stretching, but the pipeline may fail due to excessive axial tensile strains or cross sectional flattening. Finally a simplified analytical model introduced elsewhere, is enhanced to account for end effects and illustrates the formation of local buckling for relative small values of crossing angle. 相似文献
12.
The present paper addresses the mechanical behavior of buried steel pipes crossing active strike-slip tectonic faults. The pipeline is assumed to cross the vertical fault plane at angles ranging between zero and 45 degrees. The fault moves in the horizontal direction, causing significant plastic deformation in the pipeline. The investigation is based on numerical simulation of the nonlinear response of the soil–pipeline system through finite elements, accounting for large strains and displacements, inelastic material behavior of the pipeline and the surrounding soil, as well as contact and friction on the soil–pipe interface. Steel pipes with D/t ratio and material grade typical for oil and gas pipelines are considered. The analysis is conducted through an incremental application of fault displacement. Appropriate performance criteria of the steel pipeline are defined and monitored throughout the analysis. The effects of various soil and line pipe parameters on the mechanical response of the pipeline are examined. The numerical results determine the fault displacement at which the specified performance criteria are reached, and are presented in diagram form, with respect to the crossing angle. The effects of internal pressure on pipeline performance are also investigated. In an attempt to explain the structural behavior of the pipeline with respect to local buckling, a simplified analytical model is also developed that illustrates the counteracting effects of pipeline bending and axial stretching for different crossing angles. The results from the present study can be used for the development of performance-based design methodologies for buried steel pipelines. 相似文献
13.
Polynikis Vazouras Spyros A. Karamanos Panos Dakoulas 《Soil Dynamics and Earthquake Engineering》2010
The present paper investigates the mechanical behavior of buried steel pipelines, crossing an active strike-slip tectonic fault. The fault is normal to the pipeline direction and moves in the horizontal direction, causing stress and deformation in the pipeline. The interacting soil–pipeline system is modelled rigorously through finite elements, which account for large strains and displacements, nonlinear material behavior and special conditions of contact and friction on the soil–pipe interface. Considering steel pipelines of various diameter-to-thickness ratios, and typical steel material for pipeline applications (API 5L grades X65 and X80), the paper focuses on the effects of various soil and pipeline parameters on the structural response of the pipe, with particular emphasis on identifying pipeline failure (pipe wall wrinkling/local buckling or rupture). The effects of shear soil strength, soil stiffness, horizontal fault displacement, width of the fault slip zone are investigated. Furthermore, the influence of internal pressure on the structural response is examined. The results from the present investigation are aimed at determining the fault displacement at which the pipeline fails and can be used for pipeline design purposes. The results are presented in diagram form, which depicts the critical fault displacement, and the corresponding critical strain versus the pipe diameter-to-thickness ratio. A simplified analytical model is also developed to illustrate the counteracting effects of bending and axial stretching. The numerical results for the critical strain are also compared with the recent provisions of EN 1998-4 and ASCE MOP 119. 相似文献
14.
地震断层作用下的埋地管道等效分析模型 总被引：2，自引：0，他引：2
地震作用下,活动断层附近的埋地管道易发生强度屈服、局部屈曲或整体失稳等形式的破坏,建立准确、高效的埋地管道在断层作用下的计算模型,对管道的抗震设计和震后安全状态评估具有重要的实用价值。本文采用非线性弹簧模拟远离断层处埋地管道的反应,基于管土之间小变形段管道处于强化阶段,提出一种改进的管土等效分析模型,进一步减小了管土之间大变形段的分析长度,从而提高了有限元分析效率。该模型采用ALA推荐的方法计算管土间的滑动摩擦力,可以考虑土体种类的影响;用Kennedy方法确定管道的计算长度。通过与精确模型比较,验证了管土等效模型的合理性和有效性。 相似文献
15.
输气管道作为1种薄壁壳体结构，逆冲断层引起的管道压缩变形容易使其破坏。本文以大北南疆输气管道工程为例，探讨了穿越克孜尔逆冲断层的输气管道地震安全问题。在确定管道穿越处的断层倾角、设防断层位错量、表征管土相互作用的土弹簧参数以及钢管容许应变等参数后，采用壳有限元方法，分析了穿越克孜尔逆冲断层的输气管道变形反应。分析结果显示，管道在逆冲断层作用下以压缩应变为主，管道内的最大轴向压缩应变的幅值随着交角的减小而减小。在通过探槽等方法确定断层活动位置后，该管道若以小于或等于11°的交角通过克孜尔断裂，断层引起的最大轴向压缩应变和拉伸应变均在管道相应的容许应变范围内，满足相关规范的抗震要求。 相似文献
16.
北京时间2020年7月23日04时07分,西藏自治区那曲市尼玛县发生MS6.6地震,震源深度10 km,震中位置为（33.19°N,86.81°E）。主震发生当日18时50分,发生一次MS4.8强余震,震源深度为10 km。本文基于西藏、青海、新疆区域波形资料,采用ISOLA近震全波形方法对这两次地震进行震源机制反演。结果显示,尼玛MS6.6主震的最佳断层面解为:节面Ⅰ走向8°/倾角46°/滑动角?93°,节面Ⅱ走向191°/倾角44°/滑动角?87°;矩震级MW6.4,最佳矩心深度7 km。震源区应力主轴的空间取向为:主压力轴P的方位角220°、倾伏角88°,主张力轴T方位角99°、倾伏角1°。MS4.8强余震的最佳断层面解为:节面Ⅰ走向12°/倾角47°/滑动角?106°,节面Ⅱ走向214°/倾角45°/滑动角?74°;矩震级MW5.0,最佳矩心深度6 km。震源区应力主轴的空间取向为:主压力轴P的方位角207°、倾伏角78°,主张力轴T方位角113°、倾伏角1°。震源机制反演结果表明,这两次地震均为以正断型为主的地震事件,与震源区附近先前地震的震源机制有较好的一致性。结合周边地质构造和余震分布,我们认为尼玛MS6.6地震可能是由位于日干配错断裂和依布茶卡盆地西缘断裂之间的一条正断层活动所引发的。 相似文献
17.
《地震工程与结构动力学》2018,47(4):966-987
Buried pipelines are often constructed in seismic and other geohazard areas, where severe ground deformations may induce severe strains in the pipeline. Calculation of those strains is essential for assessing pipeline integrity, and therefore, the development of efficient models accounting for soil‐pipe interaction is required. The present paper is aiming at developing efficient tools for calculating ground‐induced deformation on buried pipelines, often triggered by earthquake action, in the form of fault rupture, liquefaction‐induced lateral spreading, soil subsidence, or landslide. Soil‐pipe interaction is investigated by using advanced numerical tools, which employ solid elements for the soil, shell elements for the pipe, and account for soil‐pipe interaction, supported by large‐scale experiments. Soil‐pipe interaction in axial and transverse directions is evaluated first, using results from special‐purpose experiments and finite element simulations. The comparison between experimental and numerical results offers valuable information on key material parameters, necessary for accurate simulation of soil‐pipe interaction. Furthermore, reference is made to relevant provisions of design recommendations. Using the finite element models, calibrated from these experiments, pipeline performance at seismic‐fault crossings is analyzed, emphasizing on soil‐pipe interaction effects in the axial direction. The second part refers to full‐scale experiments, performed on a unique testing device. These experiments are modeled with the finite element tools to verify their efficiency in simulating soil‐pipe response under landslide or strike‐slip fault movement. The large‐scale experimental results compare very well with the numerical predictions, verifying the capability of the finite element models for accurate prediction of pipeline response under permanent earthquake‐induced ground deformations. 相似文献
18.
2008年5月12日四川汶川8.0级地震与部分余震的震源机制解 总被引：4，自引：0，他引：4
采用区域和远台Pn或Pg初至波初动符号, 利用下半球等面积投影, 求解了2008年5月12日四川汶川8.0级地震和截止到2008年12月10日发生的部分4级以上余震的震源机制解。 汶川8.0级地震的震源机制为: 节面Ⅰ的走向为5°, 倾角为48°, 滑动角为39°; 节面Ⅱ的走向为247°, 倾角为62°, 滑动角为131°。 P轴方位角为309°, 仰角为8°, T轴方位角为208°, 仰角为54 °, B轴方位角为44°, 仰角为35°。 结合地质构造和余震空间分布, 可以确定节面Ⅱ为发震断层面。 根据震源机制解, 引发本次地震的断层活动主要表现为逆冲, 主破裂面为S67°W与该地震所在断层的走向基本一致(断裂总体走向N45°E)[1]; 主压应力轴P轴为N51 °W, 主压应力轴P轴方位与该区域构造应力场方向基本一致。 根据余震震源机制解结果, 龙门山断裂带南段发生的余震与北段发生的余震的震源机制都具有优势分布, 且两者差异明显。 早期发生在南段的余震的破裂是以逆倾滑动为主, 兼有走向滑动; 而随着时间的推移, 余震向北段迁移, 在龙门山构造的北段地震震源的破裂方式以走向滑动为主, 兼有一定的逆倾滑动; 龙门构造带南段震源应力场受主震应力场的控制, 而龙门构造带北段震源应力场不仅受区域应力场的影响, 还受主震应力场的影响。 相似文献
19.
综合利用强震数据、GPS数据和InSAR数据基于双断层模型反演熊本地震滑动分布,通过选择合理的介质模型和平滑因子,分别对数据进行单独反演和联合反演。从结果分析可以看出:三种数据联合反演的结果最优,最终滑动模型为:断层1走向为236°,倾角65°,滑动角-150.6°,最大滑动量为6m;断层2走向为206°,倾角72°,滑动角-155°,最大滑动量为4m。基于K-net和Kik-net获取永久位移快速反演得到的滑动分布结果与基于GPS数据,Sentinel-1A InSAR数据反演甚至联合反演得到滑动分布结果比较一致,表明大震后利用高密度强震动台网后快速获取滑动分布用于震后应急响应和灾害评估是切实可行的,同时认为此次地震发震断层为右旋走滑的断层系统。 相似文献