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Diffraction of plane P waves by a canyon of arbitrary shape in poroelastic half-space (Ⅱ): Numerical results and discussion

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Earthquake Science 2009年第3期22卷 223-230页

作者： Jianwen Liang zhongxian liu Department of Civil Engineering Tianjin University Tianjin 300072 China

This paper investigates in detail the nature of diffraction of plane P waves around a canyon in poroelastic half-space, and studies the effects of incident frequency, drainage condition, porosity, etc, on the diffraction of waves. It is shown that the surface displacement amplitudes of the drained case are close to those of the undrained case, however, the surface displacement amplitudes of the dry case are very different from those of the saturated （either drained or undrained） cases. There are large phase shift between the dry case and the saturated cases, as well as slightly longer resultant wavelengths for the undrained case than those for the drained case and longer resultant wavelengths for the drained case than those for the dry case. For small porosity the surface displacement amplitudes for the saturated cases are almost identical to those for the dry case; while for large porosity, the effect of drainage condition becomes significant, and the surface displacement amplitudes for the undrained case are larger than those for the drained case. As the incident frequency increases, the effect of porosity becomes significant, and more significant for the undrained case than that for the drained case. As the porosity increases, the pore pressures increase significantly but their oscillations become smoother. As the incident frequency increases, the pore pressures become more complicated.

关键词： poroelastic half-space canyon diffraction plane P wave surface displacement pore pressure

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Scattering of seismic waves by three-dimensional large-scale hill topography simulated by a fast parallel IBEM

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Earthquake Engineering and Engineering Vibration 2020年第4期19卷 855-873页

作者： liu zhongxian Shang Ce Huang Lei Liang Jianwen Li Jie Tianjin Key Laboratory of civil structure protection and reinforcing Tianjin Chengjian UniversityTianjin 300384China PC Research and Development Centre Tianjin Architecture Appraisal&Design InstituteTianjin 300072China Department of Civil Engineering Tianjin UniversityTianjin 300072China

To solve seismic wave scattering by a large-scale three-dimensional(3-D) hill topography, a fast parallel indirect boundary element method(IBEM) is developed by proposing a new construction method for the wave field, modifying the generalized minimum residual(GMRES) algorithm and constructing an Open MP plus MPI parallel model. The validations of accuracy and efficiency show that this method can solve 3-D seismic response of a large-scale hill topography for broadband waves, and overcome the weakness of large storage and low efficiency of the traditional IBEM. Based on this new algorithm architecture, taking the broadband scattering of plane SV waves by a large-scale Gaussian-shaped hill of thousands-meters height as an example, the influence of several important parameters is investigated, including the incident frequency, the incident angle and the height-width and length-width ratio of the hill. The numerical results illustrate that the amplification effect on the ground motion by a near-hemispherical hill is more significant than the narrow hill. For low-frequency waves, the scattering effect of the higher hill is more pronounced, and there is only a single peak near the top of the hill. However, for high-frequency waves, rapid spatial variation of displacement amplitude appears on the hill surface.

关键词： scattering of seismic waves 3-D hill topography indirect boundary element method(IBEM) parallel calculation

The scattering of plane P1 wave by a 3-D sedimentary basin in a fluid-saturated poroelastic half-space using IBEM

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Earthquake Science 2019年第3期32卷 143-156页

作者： Chenrui He zhongxian liu Lei liu Tianjin Key Laboratory of Civil Structure Protection and Reinforcing Tianjin Chengjian UniversityTianjin 300384China

The indirect boundary element method(IBEM)is applied to investigate the scattering of elastic waves around a 3-D sedimentary basin filled with fluid-saturated poroelastic *** on this method,the free field and scattered field can be solved according to the boundary *** the numerical accuracy has been *** effects of parameters on elastic wave scattering are studied,such as boundary condition,incident frequency,incident angle and porosity of *** results illustrate that the amplification effect of surface displacement near poroelastic sedimentary basin is *** addition,for the case of large porosity the drainage condition has a significant impact on the response *** to the fluid exchange at the interface under the drained condition,the displacement amplitude can be much larger than that under the undrained condition in present *** study can provide a theoretical basis for the anti-seismic design of engineering structures located in sedimentary basin.

关键词： indirect boundary element method scattering of elastic waves sedimentary basin fluid-saturated poroelastic medium

Dynamic interaction of twin vertically overlapping lined tunnels in an elastic half space subjected to incident plane waves

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Earthquake Science 2016年第3期29卷 185-201页

作者： zhongxian liu Yirui Wang Jianwen Liang Tianjin Key laboratory of civil structure protection and reiforcement Tianjin Chengjian University Department of Civil Engineering Tianjin University

The scattering of plane harmonic P and SV waves by a pair of vertically overlapping lined tunnels buried in an elastic half space is solved using a semi-analytic indirect boundary integration equation method. Then the effect of the distance between the two tunnels, the stiffness and density of the lining material, and the incident frequency on the seismic response of the tunnels is investigated. Numerical results demonstrate that the dynamic interaction between the twin tunnels cannot be ignored and the lower tunnel has a significant shielding effect on the upper tunnel for high-frequency incident waves, resulting in great decrease of the dynamic hoop stress in the upper tunnel; for the low-frequency incident waves, in contrast, the lower tunnel can lead to amplification effect on the upper tunnel. It also reveals that the frequency-spectrum characteristics of dynamic stress of the lower tunnel are significantly different from those of the upper tunnel. In addition, for incident P waves in low-frequency region, the soft lining tunnels have significant amplification effect on the surface displacement amplitude, which is slightly larger than that of the corresponding single tunnel.

关键词： Vertically overlapping lined tunnels Scattering Indirect boundary integration equation method(IBIEM) Soil-tunnel dynamic interaction

Seismic response of tunnel near fault fracture zone under incident SV waves

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Underground Space 2021年第6期6卷 695-708页

作者： zhongxian liu Jiaqiao liu Qiang Pei Haitao Yu Chengcheng Li Chengqing Wu Tianjin Key Laboratory of Soft Soil Properties and Engineering Environment Tianjin Chengjian UniversityTianjin 300384China Research&Development Center of Civil Engineering Technology Dalian UniversityDalian 116622China Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji UniversityShanghai 200092China School of Civil and Environmental Engineering University of Technology SydneyNSWAustralia

This study investigated the impact of a non-causative fault on the dynamic response of a nearby lined tunnel under the incidence of plane SV waves using the indirect boundary element *** effects of several critical parameters,such as the incident frequency,the inclination degree of the fault,the distance between the fault and the tunnel on the hoop stress of the lined inner and outer walls,were explored *** numerical results indicated that the non-causative fault could significantly change the hoop stress distribution of inner and outer surfaces of the *** general,for the vertically incident seismic waves,when the tunnel was located in the foot wall(under the fault),the hoop stress within the tunnel was significantly greater than that of the tunnels in the non-fault half space,with an amplification factor of up to 117%.The amplification effect became more pronounced as the fault dip angle ***,when the tunnel was located in the hanging wall(above the fault),the non-causative fault could produce a significant shielding effect on the dynamic response of the tunnel under high frequency wave incidence,with the reduction of hoop stress being up to 81%.For lowfrequency waves,though,the fault could lead to an increase of the hoop stress of the tunnel of up to 152%.The research results will provide a reference for the seismic design and safety protection of underground structures in non-causative fault sites.

关键词： Non-causative fault Indirect boundary element method Fault fracture zone Lined tunnel

Diffraction of plane P waves around an alluvial valley in poroelastic half-space

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Earthquake Science 2010年第1期23卷 35-43页

作者： zhongxian liu Jianwen Liang Department of Civil Engineering Tianjin University Tianjin 300072 China

Diffraction of plane P waves around an alluvial valley of arbitrary shape in poroelastic half-space is investigated by using an indirect boundary integral equation method. Based on the Green＇s fimctions of line source in poroelastic half-space, the scattered waves are constructed using the fictitious wave sources close to the interface of the valley and the density of ficti- tious wave sources are determined by boundary conditions. The precision of the method is verified by the satisfaction extent of boundary conditions, and the comparison between the degenerated solutions and available results in single-phase case. Finally, the nature of diffraction of plane P waves around an alluvial valley in poroelastic half-space is investigated in detail through nu- merical examples.

关键词： diffraction plane P waves alluvial valley poroelastic half-space indirect boundary integration equation method

Diffraction of plane SV waves by a cavity in poroelastic half-space

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Earthquake Engineering and Engineering Vibration 2009年第1期8卷 29-46页

作者： Liang Jianwen and liu zhongxian Department of Civil Engineering, Tianjin University, Tianjin 300072, China Professor PhD Candidate Department of Civil Engineering Tianjin University Tianjin 300072 China

This paper presents an indirect boundary integration equation method for diffraction of plane SV waves by a 2-D cavity in a poroelastic *** Green＇s functions of compressive and shear wave sources are derived based on Biot＇s theory. The scattered waves are constructed using fictitious wave sources close to the boundary of the cavity, and their magnitudes are determined by the boundary conditions. Verification of the accuracy is performed by：（1） checking the satisfaction extent of the boundary conditions, （2） comparing the degenerated solutions of a single-phased case with well- known solutions, and （3） examining the numerical stability of the solutions. The nature of diffraction of plane SV waves around a cavity in a poroelastic half-space is investigated by numerical examples.

关键词： poroelastic half-space cavity diffraction plane SV waves compressive wave source shear wave source Green's function pore pressure

含软夹层层状沉积谷地对P、SV和Rayleigh波的散射

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地震工程与工程振动 2015年第1期35卷 105-117页

作者：刘中宪黄磊天津城建大学土木工程学院天津300384 天津市软土特性与工程环境重点实验室天津300384

沉积河谷对地震动具有显著的放大效应,而软夹层的存在对其放大程度具有较大影响。采用一种高精度有限元-间接边界积分方程耦合方法,对P、SV和Rayleigh波入射下含软夹层层状沉积谷地地震响应进行计算分析。分析表明,软夹层的影响规律依... 详细信息

沉积河谷对地震动具有显著的放大效应,而软夹层的存在对其放大程度具有较大影响。采用一种高精度有限元-间接边界积分方程耦合方法,对P、SV和Rayleigh波入射下含软夹层层状沉积谷地地震响应进行计算分析。分析表明,软夹层的影响规律依赖于入射波的波型、频率和角度、软夹层的厚度和埋深等因素。整体上看,对于地表位移,较低频率地震波入射下,软夹层的放大效应比较明显,且较厚夹层在浅埋情况下的放大作用更为显著;对高频波入射则主要表现为减震效应。对于地表加速度,软夹层主要表现出降幅作用,降低幅度可达30%。另外,总体上软夹层对于P波的影响要大于对SV波的影响。

关键词：沉积谷地软弱夹层地震响应 FEM-IBIEM耦合法散射

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略论陕甘宁边区的党风廉政建设

中共福建省委党校学报 2001年第11期 13-16页

作者：林仲仙莆田市委党校

党风廉政建设是中国共产党党建的重要组成部分,是中国共产党加强自身建设的关键所在。文章对党风廉政建设史上具有典范意义的陕甘宁边区党风廉政建设情况作了回顾和思考,总结出许多今天仍然很有价值的历史经验,这对于当前我党加强党风... 详细信息

党风廉政建设是中国共产党党建的重要组成部分,是中国共产党加强自身建设的关键所在。文章对党风廉政建设史上具有典范意义的陕甘宁边区党风廉政建设情况作了回顾和思考,总结出许多今天仍然很有价值的历史经验,这对于当前我党加强党风廉政建设具有重要的借鉴意义。

关键词：陕甘宁边区党风廉政建设反腐败