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Hypoplastic constitutive modeling of wetting deformation of weathered rockfill materials

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Frontiers of Structural and Civil Engineering 2010年第1期4卷 78-91页

作者： Erich BAUER zhongzhi fu Sihong LIU Institute of Applied Mechanics Graz University of TechnologyGrazAustria Institute of Hydraulic Structures Hohai UniversityNanjing 210098China

The wetting deformation of weathered rockfill materials has been attracting growing attention from both engineers and scientists.The importance of realistic predictions of wetting deformations for high earth and rockfill dams is a strong motivation to establish a suitable constitutive model.Recently,the hypoplastic constitutive model by Gudehus and Bauer was extended by introducing solid hardness depending on the state of weathering.The extended model takes into account the influence of the current density,the effective stress state,the rate of deformation,and the time dependent process of degradation of the solid hardness.In the present paper,the performance of this model is evaluated by comparing numerical simulations with experiments obtained from a water sensitive rockfill material.In particular,triaxial compression paths and creep deformation under deviatoric stress states are considered.Finally,the constitutive model proposed is used to study the influence of a degradation of the solid hardness on the long term behavior of a hypothetical fill dam.

关键词： rockfill dams weathered granular materials hypoplasticity solid hardness creep stress relaxation

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三向变形条件下铜片止水破坏准则研究

水力发电学报 2024年第5期43卷 94-102页

作者：王立安傅中志丁强生王永生南京水利科学研究院岩土工程研究所南京210024 水利部土石坝破坏机理与防控技术重点实验室南京210029 中水北方勘测设计研究有限责任公司天津300222

铜片止水是水工混凝土结构分缝之间最重要的止水构件。混凝土结构在自重和水荷载作用下,常产生不均匀变形,使结构分缝之间的铜片止水产生拉伸(压缩)、沉陷和剪切三向变形(相对位移)。铜片止水的安全性取决于三向变形的量值,常通过三个... 详细信息

铜片止水是水工混凝土结构分缝之间最重要的止水构件。混凝土结构在自重和水荷载作用下,常产生不均匀变形,使结构分缝之间的铜片止水产生拉伸(压缩)、沉陷和剪切三向变形(相对位移)。铜片止水的安全性取决于三向变形的量值,常通过三个方向的位移单独判断,未考虑三向位移的耦合作用。本文设计制作了两种尺寸共计40个铜片止水试件,通过三向加载独立控制的试验平台对铜片止水进行了不同拉伸、沉降位移的剪切试验,研究了铜片止水的剪切变形规律和破坏形态,得到了三维位移空间中的破坏包络面,提出了一个三向变位条件下铜片止水的变形破坏准则,可用于铜片止水的安全性判断。

关键词：铜片止水结构分缝破坏准则混凝土结构

Influence of pressure and density on the rheological properties of rockfills

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Frontiers of Structural and Civil Engineering 2012年第1期6卷 25-34页

作者： Erich BAUER zhongzhi fu Sihong LIU Institute of Applied Mechanics Graz University of TechnologyGrazAustria Geotechnical Engineering Department Nanjing Hydraulic Research InstituteNanjing210029Ch Institute of Hydraulic Structures Hohai UniversityNanjing 210098China

Long-term deformations of rockfill dams can be related to the type of dam,the pre-compaction achieved during the construction of the dam,the history of loading events,the rheological properties of the rockfill material used,the seepage behavior caused by defects of the sealing,the interactions of the dam building with the foundation,and the hydrothermal phenomena of the stressed rockfill material.The present paper investigates the theological propcrtics of coarse grained rockfill materials using a hypoplastic constitutive model.Particular attention is paid to wetting deformation under different deviatoric loading states and pre-compactions.To quantify the state of weathering a so-called“solid hardness”is used in the sense of a continuum description.It is shown that an appropriate modeling of wetting deformations requires a unified description of the interaction at least between the state of weathering,the stress state,the density and the rate of deformation.The results obtained from the numerical simulations are compared with available experimental data for a rockfill material used in Xiaolangdi earth dam.

关键词： rockfills solid hardness wetting deformation hypoplasticity creep

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考虑孔隙比影响的堆石料湿化试验及湿化模型

河海大学学报（自然科学版） 2024年第1期52卷 29-36页

作者：王柳江毛航宇刘斯宏傅中志韩华强沈超敏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 南京水利科学研究院岩土工程研究所江苏南京210029

对某堆石坝的坝壳料进行了不同密实状态下的单线法三轴湿化试验,分析了湿化变形随围压、应力水平以及初始孔隙比的变化规律。结果表明:在围压和应力水平相同条件下,随着初始孔隙比的减小,堆石料湿化轴向应变和体积应变均明显降低;初始... 详细信息

对某堆石坝的坝壳料进行了不同密实状态下的单线法三轴湿化试验,分析了湿化变形随围压、应力水平以及初始孔隙比的变化规律。结果表明:在围压和应力水平相同条件下,随着初始孔隙比的减小,堆石料湿化轴向应变和体积应变均明显降低;初始孔隙比对湿化应力剪胀规律影响不大,采用对数形式的湿化剪胀方程可对不同初始孔隙比条件下的湿化应力剪胀关系进行统一描述。对指数形式的湿化轴向应变经验模型进行修正,构建了考虑初始孔隙比及应力状态影响的湿化轴向应变计算模型,并联立湿化剪胀方程推导了湿化体积应变的计算公式,通过对三轴湿化试验结果进行模拟验证了该公式的合理性。

关键词：堆石料湿化试验初始孔隙比应力剪胀方程湿化模型

基于多源数据融合的土体空间参数不确定性缩减

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水资源与水工程学报 2024年第3期35卷 183-191页

作者：贾唯龙常鹏飞李亚军钱铖郭祺李瑞杰傅中志张彬中国地质大学(北京)工程技术学院北京100083 自然资源部重大工程地质安全风险防控工程技术创新中心北京100083 山西省煤炭地质物探测绘院有限公司山西晋中030600 山西路桥第三工程有限公司山西忻州034000 南京水利科学研究院江苏南京210024

土体参数存在空间变异性,导致结构响应具有不确定性。忽视这种不确定性或采用偏差参数可能导致工程安全问题,甚至引发工程灾害。现场测量数据可用于改进对基坑开挖等岩土工程中结构响应的估计,通过SPT等直接测量方法得到的勘察数据与土... 详细信息

土体参数存在空间变异性,导致结构响应具有不确定性。忽视这种不确定性或采用偏差参数可能导致工程安全问题,甚至引发工程灾害。现场测量数据可用于改进对基坑开挖等岩土工程中结构响应的估计,通过SPT等直接测量方法得到的勘察数据与土体刚度参数直接相关,在这些数据的基础上,基于Kriging法约束随机场的条件模拟可用于改进对参数空间分布的估计。此外,当监测数据与位移等土体结构性能或响应相关时,利用集合卡尔曼滤波器(EnKF)反分析也可降低土体参数的不确定性。本文采用多源数据融合的形式将直接和间接两种方法结合在一起进行土体开挖分析,结果表明:两种方法结合使用可以显著降低土体参数的不确定性,从而降低结构响应中的不确定性。

关键词：空间变异性多源数据融合反演分析集合卡尔曼滤波器(EnKF) Kriging法不确定性缩减随机场

TC4钛合金T形接头双光束激光焊接组织与力学性能研究

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电焊机 2024年第4期54卷 154-158页

作者：吴晗周忠智赵忠华付和国史吉鹏沈阳飞机工业(集团)有限公司辽宁沈阳110034

开展了1.5 mm⊥2 mm组合的TC4钛合金T形接头双光束激光焊接工艺试验,旨在研究该T形接头的微观组织与力学性能。结果显示,T形接头焊缝区主要为网篮状组织,在上部热影响区的交叉区为少量的针状α'相以及初生α相,下部热影响区交叉区为α... 详细信息

开展了1.5 mm⊥2 mm组合的TC4钛合金T形接头双光束激光焊接工艺试验,旨在研究该T形接头的微观组织与力学性能。结果显示,T形接头焊缝区主要为网篮状组织,在上部热影响区的交叉区为少量的针状α'相以及初生α相,下部热影响区交叉区为α相等轴组织。接头力学性能显示,抗拉强度与母材相当,平均弯曲角度为33.1°。完成了典型件的焊接,接头内部没有裂纹与气孔等缺陷,为轻量化构件制造提供了有效的焊接工艺。

关键词： TC4钛合金 T形接头双光束焊接组织演变力学性能优化

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A generalized plasticity model for the stress-strain and creep behavior of rockfill materials

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Science China(Technological Sciences) 2019年第4期62卷 649-664页

作者： fu zhongzhi CHEN ShengShui WEI KuangMin Geotechnical Engineering Department Nanjing Hydraulic Research Institute Key Laboratory of Failure Mechanism and Safety Control Techniques of Earth-rock Dam

The generalized plasticity constitutive equations that simulate, in a unified manner, the stress-strain response and the creep behavior of rockfill materials are derived using the concept of elastoplasticity. A single yield surface is assumed to capture the onset of plastic strains with, however, two separate potential functions for the stress-induced plastic strains and the creep strains,respectively. The involved tensors and scalars are then specified directly, following the generalized plasticity method, to substantiate the constitutive equations. The model thus obtained is verified using triaxial compression experiments, true triaxial experiments and triaxial creep experiments. The effectiveness of the model is also demonstrated by a successful application in studying the behavior of a high concrete face rockfill dam(CFRD). It is found that for a high CFRD with a long construction period, neglecting the creep of rockfill materials during construction results in an underestimation of the deformation of the dam.The deformation and stress of the concrete slabs may also be considerably underestimated.

关键词： rockfill materials creep behavior constitutive model generalized plasticity concrete face rockfill dam(CFRD)

腹腔镜与传统开放型手术治疗腹外疝临床疗效的meta分析

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国际医药卫生导报 2024年第3期30卷 374-380页

作者：付安迪周世勇陈珂珂林忠智石若飞王振豪贵州中医药大学第二临床医学院贵阳550000 贵州中医药大学第二附属医院普外科贵阳550000

目的系统评价腹腔镜与传统开放型手术方式治疗腹外疝的临床疗效,为寻求更佳治疗方法及寻求循证医学提供支持。方法全面检索各数据库建库以来至2023年1月3日国内外发表治疗腹外疝的相关文献,搜索以腹腔镜下行疝修补术为试验组、传统开放... 详细信息

目的系统评价腹腔镜与传统开放型手术方式治疗腹外疝的临床疗效,为寻求更佳治疗方法及寻求循证医学提供支持。方法全面检索各数据库建库以来至2023年1月3日国内外发表治疗腹外疝的相关文献,搜索以腹腔镜下行疝修补术为试验组、传统开放型手术为对照组的随机对照试验,共检获相关文献468篇。对符合纳入标准的临床研究进行资料提取与质量评价,采用Review Manager 5.4软件对所纳入文献进行meta分析。结果最终纳入文献13篇,累计1044例患者,试验组527例,对照组517例。meta分析结果显示:试验组的住院时间短于对照组,差异有统计学意义[SMD=-2.16,95%CI-2.36~-1.96,Z=21.20,P<0.00001];试验组的临床并发症发生率低于对照组,差异有统计学意义[OR=0.21,95%CI 0.13~0.34,Z=6.25,P<0.00001];试验组术后感染发生率低于对照组(均P<0.00001);与对照组比较,试验组在改善术后尿潴留、改善术后疼痛及血肿方面更有优势(均P<0.00001)。结论在腹腔镜下行疝修补术较传统开放型手术住院时间缩短,能降低术后并发症发生率,改善患者生活质量。

关键词：腹外疝腹腔镜开放型手术随机对照试验 meta分析

Hypoplastic constitutive modelling of the wetting induced creep of rockfill materials

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Science China(Technological Sciences) 2012年第7期55卷 2066-2082页

作者： fu zhongzhi CHEN ShengShui LIU SiHong Geotechnical Engineering Department Nanjing Hydraulic Research InstituteNanjing 210024China Key Laboratory of Water Science and Engineering Ministry of Water ResourcesNanjing 210029China College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing 210098China

Discrete element simulations of one-dimensional compression of breakable granular assemblies were performed to investigate the capability of the exponential compression equation suggested by Bauer.The relationship between the so-called solid hardness and the particle strength was studied so as to provide a physical background for the introduction of a time-dependent solid hardness.A hyperbolic flow rule,describing the relationship between the inclination of the strain path and the stress ratio during wetting,was proposed based on typical triaxial wetting experiments on two different rockfill materials.The flow rule was then extended and incorporated into the transformed stress based hypoplastic model to capture the direction of creep strains.Meanwhile,a new density factor was introduced to the extended model to take into account the dependence of the magnitude of creep strains on the packing density.The stiffness tensor given by the extended model was discussed and the flowchart for the integration of the constitutive equation was designed.The extended model was then embedded into a finite element program and used to simulate the triaxial compression and wetting experiments performed on the aforementioned rockfill materials.Good agreement between the model predictions and the measured results lends sufficient credibility to the extended model in reproducing the stress-stain behaviour under loading and the creep behaviour during wetting.The extended model and the finite element program were also used to investigate the deformation behaviour of an earth-rock dam at the end of construction and during first impounding.The familiar phenomena such as the wetting induced settlement of the upstream shell and the movement of the dam crest towards the upstream were successfully captured by the numerical model,which confirms the feasibility of applying the extended model to dam engineering in the future.

关键词：蠕变应变堆石料润湿本构模型发育不全扩展模型离散元模拟有限元程序