地震作用下饱和土中输流管道动力特性及影响因素研究

发布时间：2018-01-31 22:39

本文关键词： 输流管道地震响应解析方法数值模拟试验研究　出处：《北京科技大学》2015年博士论文　论文类型：学位论文

【摘要】：地震对地下输流管道的破坏将会给城市人们正常的生活和企业生产造成严重影响,甚至还有可能引发一些次生灾害。地下管道的抗震问题也越来越受到工程界的高度重视,减轻地震灾害是专家与公众共同面临的难题。为了减少地震作用对输流管道造成的损毁,确保生命线工程的安全以及避免次生灾害的发生,开展地震作用下饱和土中输流管道动力响应特性研究有一定现实意义。论文围绕饱和土中输流管道的地震响应问题,采用波动理论分析计算、数值模拟以及室内模型试验三个手段来开展研究,得出了以下结论： (1)利用饱和土Biot理论及弹性介质波动理论,建立了地震波作用下饱和土中输流管道周边动应力集中问题的分析计算模型,并通过具体算例来分析了其解析解的收敛性,同时利用解析方法退化解与相关文献计算结果的吻合性比较验证了求解方法的正确性。 (2)利用建立的理论解析方法,分析了地震波入射参数(入射角度、入射频率)、饱和土体力学参数(土体孔隙率、渗透系数)、管道结构参数(剪切模量、厚度、泊松比及管道埋深)等因素对地震波作用下输流管道动力特性的影响。研究表明输流管道的剪切模量、管壁厚度以及管道埋深对动力特性影响明显,随着管道剪切模量的减小、管道壁厚以及埋深的增加,动应力集中系数会减小；土体孔隙率的增加,孔洞周边动应力集中系数会增大；随着入射波角度的变化,动应力集中系数分布也会沿着一定角度方向发生偏转,入射波自管道下方垂直入射时,管道周边动应力集中系数峰值最大；而管道的泊松比变化对管道动应力分布影响不大。 (3)采用数值软件FLAC3D对饱和土中输流管道模型地震响应问题进行了数值模拟。对比分析了饱和土中柔性管道与刚性管道对地震响应的特性,刚性管道周边监测点的竖向加速度峰值、切向应力峰值、孔隙水压峰值均大于柔性管道周边相应监测点的峰值。同样可以发现,P波作用于输流管道时管道周边动应力集中系数分布规律为管道底部最大,顶部最小,两侧次之,这与此前用解析法计算的动应力集中系数分布趋势吻合。 (4)以实验室模型试验为手段,得到了振动条件下输流管道周边测点动应力时程数据,得出了振动条件下输流管道周边动应力分布规律,对比分析了充液管道与空管道、刚性管道与柔性管道对动应力分布影响。测试结果表明,输流管道在下方振动波作用时,管道正下方产生的动应力最大,管道左右两侧产生的动应力次之,管道正上方产生的动应力最小,分布大小差异较大,管道上下方产生的动应力最大值与最小值比值达到1.37-2.36。充液管道与空管道产生的动应力值大小有较大差异,充液管道产生的动应力大于空管道周边产生的动应力。对不同材质的管道动应力测试得出弹性模量这一参数对管道周边的动应力值影响敏感,PP—R建筑排水柔性管道产生的动应变大于PVC—U建筑排水刚性管道的动应变,而PP—-R建筑排水管产生的动应力小于PVC—U建筑排水管的动应力,所以工程中采用柔性管道能在一定程度上减少地震中的管道周边动应力产生。
[Abstract]:The damage of underground pipelines will seriously affect the normal life and the production of enterprises , and even some secondary disasters may be caused . The seismic problem of underground pipelines is becoming more and more important to the public . In order to reduce the damage to the pipeline caused by the earthquake , it is necessary to ensure the safety of lifeline engineering and avoid the occurrence of secondary disasters . In this paper , three methods of wave theory analysis , numerical simulation and laboratory model test are adopted to study the seismic response of the pipeline in saturated soil , and the following conclusions are drawn : ( 1 ) The analysis and calculation model of the dynamic stress concentration problem in saturated soil under the action of seismic wave is established by using the saturated soil ' s theory and the elastic medium fluctuation theory , and the convergence of the analytical solution is analyzed by the concrete example , and the correctness of the solution method is verified by using the analytical method to resolve the agreement with the calculation results of the relevant literature . ( 2 ) The influence of seismic wave incident parameters ( incident angle , incident frequency ) , mechanical parameters of saturated soil ( soil porosity , permeability coefficient ) , pipe structure parameters ( shear modulus , thickness , Poisson ' s ratio and buried depth ) on dynamic characteristics of pipeline under the action of seismic wave is analyzed by using the established theoretical analysis method . ( 3 ) Numerical simulation is carried out on the seismic response of pipeline model in saturated soil by using numerical software FLAC3D . The characteristics of seismic response of flexible pipeline and rigid pipeline in saturated soil are analyzed . The peak value of vertical acceleration , tangential stress and pore water pressure of rigid pipeline are larger than those of the corresponding monitoring points around the flexible pipeline . ( 4 ) By using laboratory model test as a means , the dynamic stress distribution law of the periphery of the pipeline is obtained under the condition of vibration . The results show that the dynamic stress generated under the pipeline is larger than that of PVC - U building drainage pipe . The dynamic stress generated by the pipeline is larger than that of PVC - U building drainage pipe .

【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：U173;TU990.3

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