桩周土局部软化或强化对群桩性状的影响

当桩入土时,由于桩周土的性质不同将引起桩周土的局部软化或局部强化现象。提出一个能够考虑桩周土局部软化或局部强化对桩的性状影响的桩筏或桩箱共同作用的分析方法,并通过工程实例,分析不同参数情况下土对群桩基础的影响,提出一个能够考虑桩周土的软化和强化对桩性状影响的共同作用的实用方法。同时也分析了在局部软化和硬化情况下对群桩的沉降以及受力的影响。     

加筋效应对群桩相互作用系数的影响

群桩相互作用系数通常是采用平面应变模型进行分析,其研究方法具有较多的近似性。基于更为严格的虚拟桩模型,应用群桩相互作用的积分方程解答,以两桩相互作用的基本模型为例,研究加筋效应对群桩相互作用的影响。与弹性理论法和Mylonakis & Gazetas解答的对比表明,加筋效应对群桩相互作用系数有着较为明显的影响,并指出Mylonakis & Gazetas基于剪切位移法所得解答中存在的一些主要问题。     

大型地下洞室群地震模拟振动台试验研究(Ⅱ):试验方案设计

为了解大型地下洞室群在地震过程中的动态响应特征,以大渡河流域的大岗山水电站大型地下洞室群为原型,开展地震模拟振动台物理模型试验研究。作为国内外首次进行此类振动台试验研究,系统介绍整个试验的方案设计。首先,根据本次试验的目的和特性,给出试验基本简化原则,并对模型体系进行相似设计,按照完全相似模型推导出各物理量的动力相似常数、确定模拟范围、模型尺寸和相似材料配比。然后,对试验边界条件进行设计,确定了作为柔性边界的聚苯乙烯泡沫板的材料和几何参数,制作了用于测量围岩内部应力的应变砖传感器,并介绍模型制作、洞室成型与开挖等工艺步骤;最后,确定试验输入波形,并按相似理论要求进行调整,给出模型试验的加载工况。经后期试验数据的分析,证明试验条件简化合理,模型设计与制作成功。一整套模型设计方法与制作工艺,可供今后类似试验作为参考。     

浙江嵊州地区陈蔡岩群变质岩的锆石年代学研究:江绍结合带对华南印支期造山运动的响应

陈蔡岩群是华夏地块西北缘的主要前寒武纪变质基底,蕴含着有关江绍结合带构造演化的丰富信息,长期为众多学者所关注。作者最近通过路线调查和地质剖面测制,将研究区"陈蔡岩群"解体为条带状黑云斜长片麻岩、侵入其中的二长花岗岩及后期基性岩脉等。黑云斜长片麻岩的锆石年龄数据可分为多组,其中以约1800 Ma、约700Ma、220 Ma三组最为集中,前者给出了片麻岩继承锆石年龄的峰值,中者给出了片麻岩原岩时代的上限,后者为变质年龄;二长花岗岩年龄为220 Ma,与前述变质年龄对应,均为印支期构造热事件,显示了江绍结合带对华南印支期造山运动的响应。     

藏东类乌齐地区吉塘岩群的构造地层解析及主要依据

吉塘岩群沿藏东他念他翁—紫曲—吉塘一线分布,主要由片岩、片麻岩和糜棱岩组成构造岩片集合体,变形强烈,同位素年龄自古元古代—晚古生代,有必要进行解体。通过近年来的填图、测制剖面和同位素年龄的测定,并参考前人的资料及综合对比研究,对吉塘岩群(现藏东他念他翁变质杂岩体)进行了解体,将其分解为前奥陶纪—中三叠世类乌齐片麻岩套和前石炭纪吉塘岩群(>340 Ma)2套地质体。然后将类乌齐片麻岩套划分为5个构造岩石地层单元:前奥陶纪查秋赛岩组(438.2±3.6)~700.0 Ma、早二叠世都拉扎片麻岩单元(282.1±0.91)Ma、晚二叠世加压玛片麻岩单元(254.0±8.0)Ma、早三叠纪世加隆片麻岩单元(246.3±0.8)Ma、中三叠世宁达片麻岩单元(227.0±0.6)Ma。吉塘岩群的解体是该区地层研究的重要进展,有助于藏东基础地质研究。     

Effect of Cu toxicity at different salinity on selective group of juvenile pompano Trachinotus ovatus

Effects of copper toxicity and salinity shock on selective group of juvenile pompano Trachinotus ovatus were investigated.The fish were exposed to different Cu2+ concentrations of 0(blank),0.02(C1),0.05(C2),0.10(C3),and 0.15 mg·L–1(C4)at a salinity of 10‰ or 40‰ for 96 h,with the salinity of 29‰ as the control.The results showed that the effects of the acute salinity stimulation to survival rates of pompano between control(29‰)and lower or higher salinity for 96 h were not significant(p0.05).However,the survival rates in each treatment were decreased with the increase of Cu2+ concentration.The dominant factor influencing body moisture of the fish was salinity,and there was no sign that body moisture was correlated with exposure to Cu2+.The gill lamellas in high level of Cu2+ concentration(C4 treatments)were abnormal under the salinity of 40‰ and extremely curly under the salinity of 10‰.Hemorrhage in gill was observed in the two C4 treatments.Under transmission electron microscope,pillar cells in gill lamellas appeared deformed and ruptured in some areas of the epithelia in the higher concentration of Cu2+,resulting in the death of the fish due to the destruction of gill tissue,elevation of the arithmetic mean distance from water to blood,the decrease of oxygen diffusion capacity,and other physiological functions.These findings indicate that the pompano might suffer much more pressure when encountered with Cu2+ pollution and low salinity.     

潮汐河口桥墩群对波浪传播影响的数值研究

为研究河口桥墩群的消波作用,以李村河口段胶州湾快速路桥墩群为例,建立了基于波作用守恒方程的二维波浪模型,精细模拟了100年一遇高潮耦合100年一遇波高情况下,波浪通过河口桥墩群后波浪变化及波高分布,并利用物理模型试验结果对其进行了验证,二者吻合较好。数值模拟结果显示:桥墩群对河口波浪具有明显的消减作用,其透射系数随桥墩挤压面积比的增大呈线性减小趋势。     

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Policy Change and Venue Choices: Field Burning in Idaho and Washington

Grass seed farmers have burned their fields in Idaho and Washington State for decades. Field burning, however, creates small particulate matter air pollution, thus engendering a growing public backlash by the 1990s that manifested itself in new clean air advocacy groups. The new groups’ push for policy change eventually met with significant success in both cases. How did each set of advocates approach the challenge of policy change? More specifically, what kinds of policy venues did each group choose and why? This research uses the cases to explore and explain each clean air group's choices vis-à-vis hypotheses of venue choice. Three hypotheses are tested—Schattschneider's (1960 Schattschneider , E. E. 1960 . The semisovereign people . New York , NY : Holt, Rinehart, and Winston . [Google Scholar]) “expanded scope of conflict” thesis, ACF's (Sabatier and Jenkins-Smith 1999 Sabatier , P. , and H. Jenkins-Smith . 1999 . The advocacy coalition framework: An assessment . In Theories of the policy process , ed. P. A. Sabatier , 117 – 166 . Boulder , CO : Westview Press . [Google Scholar]) contention that groups strategically apply their resources in order to increase the likelihood of achieving their primary goal(s), and Pralle's (2003 Pralle , S. B. 2003 . Venue shopping, political strategy, and policy change . J. Public Policy 23 : 233 – 260 .[Crossref] , [Google Scholar], 2010 Pralle , S. B. 2010 . Shopping around: Environmental organizations and the search for policy venues . In Advocacy organizations and collective action , ed. A. Prakash and M. K. Gugerty , 177 – 203 . Cambridge , MA : Cambridge University Press .[Crossref] , [Google Scholar]) thesis that internal group constraints deter groups from moving into new venues.     

利用层次Voronoi图进行点群综合

通过距离权重描述点的重要程度,采用改进的k-means算法得到点群的聚类中心,进而以聚类中心为基础,构建了层次加权Voronoi图与Voronoi层次树结构.以点群的分布范围、排列方式与密度为度量,给出了基于Voronoi层次树结构的点群综合方法,确保了点群综合前后在空间形态分布上的一致性.结合地理统计学计算,对综合方法作了进一步的量化评估与优化.经验证,本文方法是可行、有效的.