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Three-dimensional numerical analysis of the interaction of two crossing tunnels in soft clay

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Underground Space 2019年第4期4卷 310-327页

作者： Jin yin-Fu Zhu Bing-Qing yin zhen-yu Zhang Dong-Mei Department of Civil and Environmental Engineering The Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina China Development Bank Sichuan Branch No.120Tiantai RoadGaoxin DistrictChengduSichuan ProvinceChina Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji UniversityShanghai 200092China Department of Geotechnical Engineering Tongji UniversityShanghai 200092China

Recently,with the development of underground construction,multi-tunnel engineering has become a matter of concern since the interaction between tunnels at close ranges could cause additional deformation in strata as well as surrounding structures and even serious damage to surface *** tunnel displacement and soil deformation problems can be effectively predicted using numerical methods considering the influence of various factors,such as the anisotropic nature of soft *** this end,the anisotropic elastoplastic constitutive S-CLAY1 is implemented in finite element code to investigate deformation problems in the strata and nearby structures caused by the excavation of *** paper focuses in particular on configurations of two crossing *** 3D numerical simulations using ABAQUS enable successive analyses conducted for tunnels at different spacings(1.5D,2.5D,3.5D and 4.5D,where D is the tunnel diameter)of configurations aligned *** results,including the ground settlement,lining force and moment,and tunnel convergence,are *** each aspect,the most unfavorable case is determined by comparing the results of different *** investigation can provide a reference for multi-tunnels design and construction.

关键词： Multi-tunnels Anisotropy Clay Ground loss Finite element Constitutive relation

Immunological protection of small bowel by simultaneously transplanted liver graft in pigs

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Hepatobiliary & Pancreatic Diseases International 2009年第4期8卷 363-369页

作者： yin, zhen-yu Li, Ning Wang, Xiao-Ming Ni, Xiao-Dong Jiang, Feng Li, You-Sheng Li, Jie-Shou Nanjing Univ Sch Med Jinling Hosp Inst Gen Surg Nanjing 210002 Peoples R China Xiamen Univ Zhongshan Hosp Dept Hepatobiliary Surg Xiamen 361004 Peoples R China

BACKGROUND: A simultaneously transplanted liver shields a bowel graft from immunologic attack in small animals, while the possible immuno-tolerance induced by the liver in liver and small bowel transplantation (LSBT) is uncertain in large animal models. To investigate the clinically suspected beneficial effect of the liver on small bowel allograft, we developed a new model of composite LSBT in the pig. METHODS: Seventy outbred long-white pigs were randomized into four groups. LSBT without immunosuppressive treatment (n=10, group A); LSBT with routine immunosuppressive treatment (n=10, group B); LSBT with a lower dose of immunosuppressive treatment (n=10, group C); and small bowel segment allotransplantation without immunosuppressive treatment (n=10, group D). RESULTS: There was no remarkable difference in survival time between groups A and D (10.33 vs. 12.89 days, P>0.05), but the initial time of acute rejection of the intestinal graft in group A was clearly delayed when compared to group D (8.22 vs. 4.33 days, P0.05), initial acute rejection time (25.40 vs. 22.13 days, P>0.05) or rejection score did not differ between groups B and C within one postoperative month. CONCLUSIONS: Compared to isolated segment small bowel allotransplantation, the intestinal graft in LSBT (group A) had a delayed initial time of acute rejection and a lower postoperative acute rejection score, and a lower dose of immunosuppressive treatment led to persistent graft immuno-tolerance in LSBT. Thus the simultaneously transplanted liver graft may reduce the risk of intestinal

关键词： liver transplantation small bowel transplantation porcine allotransplantation rejection immuno-tolerance

Uniqueness of rate-dependency, creep and stress relaxation behaviors for soft clays

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Journal of Central South University 2015年第1期22卷 296-302页

作者：朱启银尹振宇徐长节殷建华夏小和 Department of Civil Engineering Shanghai Jiao Tong University State Key Laboratory for Geomechanics and Deep Underground Engineering(China University of Mining and Technology) Lunan University Ecole Centrale de NantesUMR CNRS Ge M Nantes France School of Civil Engineering and Architecture Departments East China Jiaotong University Department of Civil and Environmental Engineering Hong Kong Polytechnic University

This work focuses on the uniqueness of rate-dependency, creep and stress relaxation behaviors for soft clays under one-dimensional condition. An elasto-viscoplastic model is briefly introduced based on the rate-dependency of preconsolidation pressure. By comparing the rate-dependency formulation with the creep based formulation, the relationship between rate-dependency and creep behaviors is firstly described. The rate-dependency based formulation is then extended to derive an analytical solution for the stress relaxation behavior with defining a stress relaxation coefficient. Based on this, the relationship between the rate-dependency coefficient and the stress relaxation coefficient is derived. Therefore, the uniqueness between behaviors of rate-dependency, creep and stress relaxation with their key parameters is obtained. The uniqueness is finally validated by comparing the simulated rate-dependency of preconsolidation pressure, the estimated values of secondary compression coefficient and simulations of stress relaxation tests with test results on both reconstituted Illite and Berthierville clay.

关键词： soft clays creep rate-dependency stress relaxation oedometer test

Dynamic Regulation of Hydrogen Bonding Networks and Solvation Structures for Synergistic Solar‑Thermal Desalination of Seawater and Catalytic Degradation of Organic Pollutants

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Nano-Micro Letters 2025年第2期17卷 548-565页

作者： Ming‑yuan yu Jing Wu Guang yin Fan‑zhen Jiao Zhong‑zhen yu Jin Qu Beijing Key Laboratory of Advanced Functional Polymer Composites Beijing University of Chemical TechnologyBeijing 100029People’s Republic of China State Key Laboratory of Organic‑Inorganic Composites College of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing 100029People’s Republic of China

Although solar steam generation strategy is efficient in desalinating seawater,it is still challenging to achieve continuous solar-thermal desalination of seawater and catalytic degradation of organic ***,dynamic regulations of hydrogen bonding networks and solvation structures are realized by designing an asymmetric bilayer membrane consisting of a bacterial cellulose/carbon nanotube/Co_(2)(OH)_(2)CO_(3)nanorod top layer and a bacterial cellulose/Co_(2)(OH)_(2)CO_(3)nanorod(BCH)bottom ***,the hydrogen bonding networks inside the membrane can be tuned by the rich surface–OH groups of the bacterial cellulose and Co_(2)(OH)_(2)CO_(3)as well as the ions and radicals in situ generated during the catalysis ***,both SO_(4)^(2−)and HSO_(5)−can regulate the solvation structure of Na^(+)and be adsorbed more preferentially on the evaporation surface than Cl^(−),thus hindering the de-solvation of the solvated Na^(+)and subsequent nucleation/growth of ***,the heat generated by the solar-thermal energy conversion can accelerate the reaction kinetics and enhance the catalytic degradation *** work provides a flow-bed water purification system with an asymmetric solar-thermal and catalytic membrane for synergistic solar thermal desalination of seawater/brine and catalytic degradation of organic pollutants.

关键词： Solar steam generation Seawater desalination Catalytic degradation Bacterial cellulose Cobalt hydroxycarbonate nanorods

Continuous regional arterial infusion and laparotomic decompression for severe acute pancreatitis with abdominal compartment syndrome

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World Journal of Gastroenterology 2011年第44期17卷 4911-4916页

作者： Zhi-Gang Deng Jian-yin Zhou zhen-yu yin You-yuan Peng Fu-Qiang Wang Xiao-Min Wang Department of Hepatobiliary Surgery Xiamen University Zhongshan Hospital Xiamen 361004 Fujian Province China

AIM:To evaluate the therapeutic effects of abdominal decompression plus continuous regional arterial infusion(CRAI) via a drug delivery system(DDS) in severe acute pancreatitis(SAP) patients with abdominal compartment syndrome(ACS).METHODS:We presented our recent experience in 8 patients with *** patients developed clinical ACS,which required abdominal *** the operation,a DDS was inserted into the peripancreatic artery(the catheter was inserted from the right gastroepiploic artery until it reached the junction between the pancreaticoduodenal and gastroduodenal artery).Through this DDS,a protease inhibitor,antibiotics and octreotide were infused *** duration of the regional artery infusion ranged from 8 to 41 *** outcomes and the changes in the APACHE Ⅱ score,computed tomography(CT) severity index and intraabdominal pressure(IAP) of the patients were retrospectively ***:Eight patients with an initial APACHE Ⅱ score of 18.9(range,13-27) and a Balthazar CT severity index of 9.1(range,7-10) developed severe local and systemic *** patients underwent subsequent surgical decompression and CRAI therapy because of intra-abdominal hypertension(IAH).After a mean interval of 131.9 ± 72.3 d hospitalization,7 patients recovered with decreased APACHE Ⅱ scores,CT severity indexes and *** mean APACHE Ⅱ score was 5.4(range,4-8),the CT severity index was 2.3(range,1-3),and IAP decreased to 7.7 mmHg(range,6-11 mmHg) 60 d after *** patient died of multiple organ failure 1 wk after ***:CRAI and laparotomic decompression might be a therapeutic option for SAP patients with ACS.

关键词： Severe acute pancreatitis Arterial infusion Laparotomy Abdominal compartment syndrome

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三维有序排列多孔介质对流换热的数值研究

物理学报 2014年第21期63卷 201-206页

作者：王平尹玉真沈胜强大连理工大学能源与动力学院大连116024

利用CFD软件数值研究了颗粒三维有序堆积多孔介质的对流换热问题.采用颗粒直径分别为14 mm,9.4 mm和7 mm的球形颗粒有序排列构成多孔介质骨架,在多孔骨架的上方有一恒热流密度的铜板.采用流固耦合的方法研究了槽通道内温度分布和局部对... 详细信息

利用CFD软件数值研究了颗粒三维有序堆积多孔介质的对流换热问题.采用颗粒直径分别为14 mm,9.4 mm和7 mm的球形颗粒有序排列构成多孔介质骨架,在多孔骨架的上方有一恒热流密度的铜板.采用流固耦合的方法研究了槽通道内温度分布和局部对流换热系数的分布以及对流换热的影响因素.研究结果表明:热渗透的厚度和温度边界层的厚度在流动方向上逐渐增大,并且随流量的增加而减小;当骨架的导热系数比较高时,对流换热随颗粒直径的减小而略有增大;对流换热系数随聚丙烯酰胺溶液浓度的增大而减小,黏性耗散减弱了对流换热.

关键词：多孔介质温度场局部对流换热系数数值模拟

超大次循环荷载下超固结黏土的长期不排水力学特性研究

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岩土工程学报 2017年第12期39卷 2219-2225页

作者：韩剑姚仰平尹振宇北京航空航天大学交通科学与工程学院北京100191 同济大学地下建筑与工程系岩土及地下工程教育部重点实验室上海200092 南特中央理工大学土木与力学工程研究所法国南特44300

风、波浪等荷载具有超大循环次数的特征,极大影响黏土的长期不排水动力特性,是黏土地基基础设计的关键问题之一。针对现有动力试验荷载循环次数不足的现状,以超固结度为4的重塑土试样为研究对象,开展了一系列不排水三轴动力试验,研究了... 详细信息

风、波浪等荷载具有超大循环次数的特征,极大影响黏土的长期不排水动力特性,是黏土地基基础设计的关键问题之一。针对现有动力试验荷载循环次数不足的现状,以超固结度为4的重塑土试样为研究对象,开展了一系列不排水三轴动力试验,研究了在超大次(比如超过10~6次)循环加载情况下黏土的相关特性。试验结果表明,在对称循环加载作用下,饱和黏土存在循环应力比门槛值为0.44~0.48。在循环加载初期,试样的轴应变及孔压的变化与前人对黏土动力试验研究结果一致。然而,随着循环加载次数的增加,动轴向应变减小,累积轴向应变增加;尤其是加载过程中由正孔压降低到负孔压。针对这一新的发现,增加了一个超固结土的蠕变试验结果进行了分析解释,为研究超大次循环荷载下超固结黏土的长期不排水力学特性的机理提供了新的思路。

关键词：黏土超大循环次数蠕变孔隙水压力不排水三轴试验

各向异性砂土渗流潜蚀流体动力学-离散元流固耦合分析

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岩土力学 2024年第1期45卷 302-312页

作者：周闯钱建固尹振宇同济大学地下建筑与工程系上海200092 同济大学岩土及地下工程教育部重点实验室上海200092 香港理工大学土木与环境系中国香港

针对具有初始各向异性的间断级配砂土细粒潜蚀问题,引入可以考虑颗粒投影面积影响的Ganser拖曳力计算模型,实现非球形颗粒的计算流体动力学(computational fluid dynamics,简称CFD)和离散元(discrete element method,简称DEM)的双相耦... 详细信息

针对具有初始各向异性的间断级配砂土细粒潜蚀问题,引入可以考虑颗粒投影面积影响的Ganser拖曳力计算模型,实现非球形颗粒的计算流体动力学(computational fluid dynamics,简称CFD)和离散元(discrete element method,简称DEM)的双相耦合。通过与单颗粒下沉试验的对比,验证了该数值方法在解决异形颗粒与流体相互作用时的适用性。在此基础上,生成具有不同沉积方向和不同细粒含量的初始各向异性试样,模拟向上渗流潜蚀试验,并在试验中监测细粒流失量、强弱力链组成以及颗粒组构变化等宏微观特性,研究不同充填状态下(欠填充和过填充)不同组构各向异性土体渗流潜蚀特征。之后,对受潜蚀前后的试样进行了排水三轴试验,探究渗流对土体强度弱化的影响。结果表明,过填充试样质量损失随着颗粒沉积角度的增大而增大,而欠填充试样质量损失随沉积角度先增大后减小;欠填充试样细粒损失主要来源于低连通性细颗粒,而对于过填充试样,潜蚀则会导致低连通性和高连通性细颗粒数量同时减小。此外,三轴试验表明,潜蚀致土体峰值强度发生显著弱化,且峰值强度随沉积角度的变化也会受到土体充填状态的影响。

关键词： CFD-DEM 渗流潜蚀异形颗粒拖曳力模型各向异性微观组构

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冻结砂土三轴试验中颗粒破碎研究

岩土工程学报 2015年第3期37卷 544-550页

作者：马玲齐吉琳余帆尹振宇中国科学院寒区旱区环境与工程研究所冻土工程国家重点实验室甘肃兰州730000 中国科学院大学北京100049 北京建筑大学土木与交通工程学院北京100044 南特中央理工大学土木工程系法国南特44321

压力作用下颗粒发生破碎是引起砂土力学特性变化的重要因素之一,冻结砂土也是如此。对冻结砂土进行了不同温度和围压下的三轴剪切试验,并筛分得到三轴试验前后的颗粒大小分布曲线。通过引入Hardin定义的颗粒破碎率Br,分析了围压与颗粒... 详细信息

压力作用下颗粒发生破碎是引起砂土力学特性变化的重要因素之一,冻结砂土也是如此。对冻结砂土进行了不同温度和围压下的三轴剪切试验,并筛分得到三轴试验前后的颗粒大小分布曲线。通过引入Hardin定义的颗粒破碎率Br,分析了围压与颗粒破碎的关系及颗粒破碎对冻土抗剪强度的影响。结果表明:在温度为-0.5℃,-1℃,-2℃,-5℃和围压为0.5,2,5,10 MPa的条件下,三轴剪切过程中会产生较为可观的颗粒破碎;颗粒破碎率Br随围压增大,到达一定围压后Br不再随着围压的增大发生明显变化,即存在一个颗粒不再发生明显破碎的临界围压σr。结合前人研究发现,-5℃下一般工程关心的围压范围内压融对冻土力学特性没有显著影响,而颗粒破碎起控制性作用。分析表明:-5℃条件下在不同的围压范围颗粒破碎对抗剪强度具有不同的影响。试验所采用的围压范围内,随着围压的增大,颗粒破碎率增大使得冻土的抗剪强度降低;破碎率达到极限以后,由于破碎的颗粒重排列又导致抗剪强度有所提高。

关键词：冻结砂土颗粒破碎三轴试验压融强度