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Application of Smoothed Particle Hydrodynamics(SPH)for the Simulation of Flow-Like Landslides on 3D Terrains

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Computer Modeling in Engineering & Sciences 2023年第4期135卷 357-376页

作者： Binghui Cui liaojun zhang College of Civil and Transportation Engineering Hohai UniversityNanjing210000China College ofWater Conservancy and Hydropower Engineering Hohai UniversityNanjing210000China

Flow-type landslide is one type of landslide that generally exhibits characteristics of high flow velocities,long jump distances,and poor predictability.Simulation of its propagation process can provide solutions for risk assessment and mitigation design.The smoothed particle hydrodynamics(SPH)method has been successfully applied to the simulation of two-dimensional(2D)and three-dimensional(3D)flow-like landslides.However,the influence of boundary resistance on the whole process of landslide failure is rarely discussed.In this study,a boundary condition considering friction is proposed and integrated into the SPH method,and its accuracy is verified.Moreover,the Navier-Stokes equation combined with the non-Newtonian fluid rheologymodel was utilized to solve the dynamic behavior of the flow-like landslide.To verify its performance,the Shuicheng landslide event,which occurred in Guizhou,China,was taken as a case study.In the 2D simulation,a sensitivity analysis was conducted,and the results showed that the shearing strength parameters have more influence on the computation accuracy than the coefficient of viscosity.Afterwards,the dynamic characteristics of the landslide,such as the velocity and the impact area,were analyzed in the 3D simulation.The simulation results are in good agreement with the field investigations.The simulation results demonstrate that the SPH method performs well in reproducing the landslide process,and facilitates the analysis of landslide characteristics as well as the affected areas,which provides a scientific basis for conducting the risk assessment and disaster mitigation design.

关键词： Flow-like landslides smoothed particle hydrodynamics non-Newtonian fluid boundary treatment

Investigation of the Free Vibrations of Radial Functionally Graded Circular Cylindrical Beams Based on Differential Quadrature Method

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Computer Modeling in Engineering & Sciences 2022年第7期132卷 23-41页

作者： Xiaojun Huang liaojun zhang Renyu Ge Hanbo Cui Zhedong Xu College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing210098China School of Architecture and Civil Engineering Anhui Polytechnic UniversityWuhu241000China

In the current research,an effective differential quadrature method(DQM)has been developed to solve natural frequency and vibration modal functions of circular section beams along radial functional gradient.Based on the high-order theory of transverse vibration of circular cross-section beams,lateral displacement equation was reconstructed neglecting circumferential shear stress.Two equations coupled with deflection and rotation angles were derived based on elastic mechanics theory and further simplified into a constant coefficient differential equation with natural frequency as eigenvalue.Then,differential quadrature method was applied to transform the eigenvalue problem of the derived differential equation into a set of algebraic equation eigenvalue problems.Natural frequencies of the free vibrations of cylindrical beams with circular cross-sections were calculated at one time,and corresponding modal functions were solved together.The obtained numerical results indicated that the natural frequencies of functionally graded(FG)circular cylindrical beams obtained using differential quadrature method agreed with the results reported in related literatures.In addition,influences of varying gradient parameters on the modal shapes of circular cylindrical beams were found to be strongly consistent with previous studies.Numerical results further validated the feasibility and accuracy of the developed differential quadrature method in solving the transverse vibration of FG circular cross-section beams.

关键词： Functionally graded materials circular cylindrical beams natural frequency modal function differential quadrature method

基于改进YOLOv5的钢材表面缺陷识别方法

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Journal of Southeast University(English Edition) 2024年第1期40卷 49-57页

作者：王硕张燎军尹国江河海大学土木与交通学院南京210098 河海大学水利水电学院南京210098 河海大学水利部水工金属结构安全检测中心南京210098

由于传统的机器视觉检测方法在小尺度钢材表面缺陷识别中存在检测精度较差的问题,提出了一种基于改进YOLOv5算法的钢材表面缺陷无损识别方法.将Res2Block模块应用于YOLOv5算法的骨干,在扩大感受野的同时提高计算效率;在YOLOv5算法的颈... 详细信息

由于传统的机器视觉检测方法在小尺度钢材表面缺陷识别中存在检测精度较差的问题,提出了一种基于改进YOLOv5算法的钢材表面缺陷无损识别方法.将Res2Block模块应用于YOLOv5算法的骨干,在扩大感受野的同时提高计算效率;在YOLOv5算法的颈部融合g^(n) Conv结构,以提高表面缺陷识别方法的计算性能.为验证所提方法的有效性,进行了不同模块组合的消融试验,并与其他目标检测方法进行了对比.结果表明:所提方法在钢材表面缺陷识别中实现了67.8%的mAP和86.0%的F_(1)值;与原始YOLOv5算法相比,所提方法在小尺度钢材表面缺陷识别方面表现更为优越;与其他目标检测方法如SSD、YOLOv3、YOLOv5-Lite、YOLOv8相比,所提方法的计算精度有明显的提高.

关键词：钢材缺陷检测卷积神经网络 YOLO

考虑混凝土强度随机不均匀分布的重力坝动力损伤研究

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地震工程与工程振动 2024年第1期44卷 128-136页

作者：马天骁张燎军沈德建王伟强沈阳农业大学水利学院辽宁沈阳110866 河海大学水利水电学院江苏南京210098 河海大学土木与交通学院江苏南京210098

重力坝所采用的大体积混凝土受到其固有特性、浇筑时的施工质量等影响容易导致强度的不均匀性。在目前的混凝土坝抗震分析中,一般将混凝土看成是一种强度分布均匀的材料,对于强度的不均匀性对大坝动力损伤的影响研究不多。基于混凝土塑... 详细信息

重力坝所采用的大体积混凝土受到其固有特性、浇筑时的施工质量等影响容易导致强度的不均匀性。在目前的混凝土坝抗震分析中,一般将混凝土看成是一种强度分布均匀的材料,对于强度的不均匀性对大坝动力损伤的影响研究不多。基于混凝土塑性损伤理论及Weibull概率分布模型,采用Python语言对ABAQUS进行二次开发。在考虑混凝土塑性损伤的前提下,研究了混凝土强度随机不均匀分布对重力坝坝体和基岩损伤的影响。在计算中综合考虑了坝体和基岩的动力损伤、大坝与库水相互作用、无限地基辐射阻尼等,对比分析了坝体和基岩整体在各个不均匀度下震后损伤区域分布、坝体损伤面积比和损伤耗散能等动力响应,揭示了混凝土强度不均匀程度对大坝及基岩地震损伤的影响规律,研究结果可为重力坝相关的设计和施工提供参考。

关键词：重力坝 Weibull分布材料不均匀动力损伤

Analysis of seismic disaster failure mechanism and dam-break simulation of high arch dam

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Earthquake Engineering and Engineering Vibration 2014年第2期13卷 327-335页

作者： zhang Jingkui zhang liaojun Anhui and Huaihe River Institute of Hydraulic Research College of Water Conservancy and Hydropower Engineering Hohai University

Based on a Chinese national high arch dam located in a meizoseismal region, a nonlinear numerical analysis model of the damage and failure process of a dam-foundation system is established by employing a 3-D deformable distinct element code(3DEC) and its re-development functions. The proposed analysis model considers the dam-foundation-reservoir coupling effect, infl uence of nonlinear contact in the opening and closing of the dam seam surface and abutment rock joints during strong earthquakes, and radiation damping of far fi eld energy dissipation according to the actual workability state of an arch dam. A safety assessment method and safety evaluation criteria is developed to better understand the arch dam system disaster process from local damage to ultimate failure. The dynamic characteristics, disaster mechanism, limit bearing capacity and the entire failure process of a high arch dam under a strong earthquake are then analyzed. Further, the seismic safety of the arch dam is evaluated according to the proposed evaluation criteria and safety assessment method. As a result, some useful conclusions are obtained for some aspects of the disaster mechanism and failure process of an arch dam. The analysis method and conclusions may be useful in engineering practice.

关键词： high arch dam complex foundation 3DEC disaster mechanism dam-break process simulation seismic safety evaluation

Transverse free vibration analysis of a tapered Timoshenko beam on visco-Pasternak foundations using the interpolating matrix method

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Earthquake Engineering and Engineering Vibration 2019年第3期18卷 567-578页

作者： zhang Jinlun Ge Renyu zhang liaojun Institute of Engineering Safety and Disaster Prevention Hohai University Nanjing 210098 China Key Laboratory for Mechanics Anhui Polytechnic University Wuhu 241000 China

The characteristics of transverse free vibration of a tapered Timoshenko beam under an axially conservative compression resting on visco-Pasternak foundations are investigated by the interpolating matrix method. The research is executed in view of a three-parameter foundation which includes the eff ects of the Winkler coeffi cient, Pasternak coeffi cient and damping coeffi cient of the elastic medium. The governing equations of free vibration of a non-prismatic Timoshenko beam under an axially conservative force resting on visco-Pasternak foundations are transformed into ordinary diff erential equations with variable coeffi cients in light of the bending rotation angle and transverse displacement. All the natural frequencies orders together with the corresponding mode shapes of the beam are calculated at the same time, and a good convergence and accuracy of the proposed method is verifi ed through two numerical examples. The infl uences of foundation mechanical characteristics together with rotary inertia and shear deformation on natural frequencies of the beam with diff erent taper ratios are analyzed. A comprehensive parametric numerical study is carried out emphasizing the primary parameters that describe the dynamic property of the beam.

关键词： interpolating matrix method vibration analysis tapered Timoshenko beam visco-Pasternak foundation

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基于耐震时程法的特高拱坝极限抗震能力研究

振动与冲击 2022年第11期41卷 217-224页

作者：马天骁张燎军张汉云史俊飞翟亚飞河海大学水利水电学院南京210098

在对300 m级特高拱坝进行抗震安全评价时,常常面临着工程条件复杂、有限元模型自由度数目多、计算耗时较长、效率较低等问题。为了提高分析效率,节约计算成本,采用了耐震时程法来分析特高拱坝及坝基的动力损伤行为,并进行极限抗震能力... 详细信息

在对300 m级特高拱坝进行抗震安全评价时,常常面临着工程条件复杂、有限元模型自由度数目多、计算耗时较长、效率较低等问题。为了提高分析效率,节约计算成本,采用了耐震时程法来分析特高拱坝及坝基的动力损伤行为,并进行极限抗震能力研究。基于耐震时程法理论,以《水电工程水工建筑物抗震设计规范》中的标准反应谱为目标谱,采用非线性最小二乘法生成精度较高的3条耐震时程曲线。以我国西南地区某300 m级特高拱坝为例,建立了坝体—基岩三维非线性有限元分析模型,并同时考虑地震动的输入、坝体及基岩的损伤开裂、横缝的动态开合等关键问题。通过考察拱冠梁最大相对位移、横缝最大开度、坝体损伤体积比、损伤耗能等指标来综合评价大坝的极限抗震能力。结果表明,耐震时程法能够很好的反映出特高拱坝在不同强度地震动作用下的动力响应,且计算效率较高。

关键词：特高拱坝耐震时程法混凝土损伤极限抗震能力

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基于黏弹性边界的地震波斜入射方法研究

水力发电学报 2015年第1期34卷 183-188页

作者：陈立张燎军河海大学水利水电学院南京210098

地震动输入的形式的选取是计算水工建筑物地震反应的重要问题。本文在前人工作的基础上,采用工程波动理论,总结推导出基于黏弹性边界的二维P波和VS波的等效荷载计算公式,进而施加在人工边界上,实现地震波的斜输入。通过斜输入算例表明,... 详细信息

地震动输入的形式的选取是计算水工建筑物地震反应的重要问题。本文在前人工作的基础上,采用工程波动理论,总结推导出基于黏弹性边界的二维P波和VS波的等效荷载计算公式,进而施加在人工边界上,实现地震波的斜输入。通过斜输入算例表明,本文的黏弹性边界地震波斜输入方法很好反映P波和VS波的斜入射情况,具有较高的精度,能够有效应用于地震斜输入过程中结构与地基的相互作用的计算中。

关键词：水工结构时域地震反应动力有限元法地震波斜入射黏弹性边界

等效三维一致黏弹性边界单元及其在拱坝抗震分析中的应用

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水力发电学报 2009年第5期28卷 169-173,194页

作者：程恒张燎军张汉云河海大学水文水资源与水利工程科学国家重点实验室南京210098 河海大学水利水电工程学院南京210098

基于大型结构分析软件ADINA,提出了等效三维一致黏弹性人工边界单元以及在该边界上实现波动输入的方法和技术。将其应用于国内某高拱坝的坝体-地基-库水系统的地震反应分析,研究大坝在三向地震荷载作用下的动力响应,并与传统无质量地基... 详细信息

基于大型结构分析软件ADINA,提出了等效三维一致黏弹性人工边界单元以及在该边界上实现波动输入的方法和技术。将其应用于国内某高拱坝的坝体-地基-库水系统的地震反应分析,研究大坝在三向地震荷载作用下的动力响应,并与传统无质量地基模型的计算结果进行对比。结果表明地基辐射阻尼有效降低了坝体的地震响应,该方法应用方便且具有良好的计算精度和稳定性。

关键词：结构动力学拱坝抗震分析等效一致黏弹性人工边界单元辐射阻尼 ADINA