基于弹性半空间理论的土石混填路基压实度确定方法

针对现有路基压实度检测方法用于土石混填路基存在的诸多局限性与不足，提出了一种基于贯入试验的土石混填路基的压实度快速检测方法.首先，利用在受载前后岩土颗粒体积不变的条件，建立了土石混填料孔隙率与变形模量的变化关系.在此基础上，将土石混填路基视为半无限弹性空间，引进分级加载的思想，基于布辛奈斯克解导得了均布荷载条件下的包含初始孔隙率参数的荷载与变形计算公式，再将其转化为压实度与初始孔隙率之间的关系，从而确定压实度.该公式中仅包含两个基本参数，可由曲线拟合求出.最后，利用自行设计的实验装置开展了现场试验，对该方法进行了验证.试验对比数据表明，得到的压实度精度满足工程要求.     

强夯法加固风化花岗岩高路堤现场试验检测

利用风化花岗岩混合料,对潍坊市郊区深坑中高填路堤进行分层强夯填筑,通过不同夯击能下的强夯土体变形试验,确定了关键施工参数.采用压实度、载荷试验和瑞利面波等原位测试手段测定了强夯前后路基的压实程度和力学性能,显示强夯施工后填料层变形模量能普遍提高1.6—3.5倍,锤底下填料层的变形模量要大于地表夯点间的变形模量,干密度和孔隙比数值变化也反映类似规律.在填土深度5m范围内,夯后面波速度明显提高,达到240—320m/s左右,加固效果明显.建立了瑞利波波速和土基变形模量以及干密度间的表达式,达到快速检测土石混填路基压实度和评价路基整体质量与力学性能的目的.     

基于孔隙介质理论的路基压实度确定方法

为克服以往路基压实度快速检测法中需要繁琐的标定试验及忽视初始地应力对变形参数影响的缺陷,建立了路基压实度快速检测新方法.首先,基于孔隙介质理论,研究了孔隙率、变形模量及密度随路基材料变形而变化的规律;其次,引入分层总和法和分级加载思想,考虑初始地应力和路基变形均影响路基力学参数变化的特征,建立静力贯入条件下贯入荷载-沉降解析关系;然后,在路基静力贯入试验测得荷载-沉降试验曲线的基础上,利用自适应遗传退火算法反演得路基贯入荷载-沉降解析关系中的各参数,从而建立基于孔隙介质理论的路基压实度确定方法;最后,通过工程实例对比可知,本文方法精确度满足工程要求,检测过程中无需繁琐的灌水法标定试验,能快速准确地检测路基压实度,表明了本文方法的合理性和可行性.     

重复压缩-回弹条件下土石混填体变形规律与压实指标相关性试验研究

从湖南省龙(山)—永(顺)高速公路大坝隧道弃碴填筑体取样,开展土石混填体压实模拟及压实评价指标室内对比试验。研究结果表明:土石混填体压缩曲线呈上凸型;回弹曲线平缓圆滑,呈微下凹型;第i+1次压缩回弹曲线均位于第i次曲线下方,线形相似;土石混填体变形具有记忆效应;湿化对土石(灰岩)混填体压实变形特征影响不明显;分级加载比1次加载产生的变形大;随着循环荷载和加载次数增加,累积总变形、累积塑性变形和累积塑性变形率增大,压缩5次基本不再增大;分级总变形、分级塑性变形和分级塑性变形率随加载次数增加而减小,减小率也不断减小;当循环荷载超过400 kPa时,分级总变形、分级塑性变形和分级塑性变形率基本接近;在工地碾压过程中,采用高吨位压路机或者轻重机具组合碾压5次,能有效提高土石混填体的压实度;压实评价指标K30(地基系数)、Ev1(静态变形模量)与e(孔隙比)具有较好的相关性,Ev2(静态变形模量)、Evd(动态变形模量)与e(孔隙比)的相关性较差;K30和Ev1可作为土石混填体压实质量评价指标。     

基于静力贯入的路基压实度确定方法

为了建立公路路基压实度检测的新方法,在研究静力贯入路基变形力学机理基础上,深入考虑路基土体变形的非线性特征,引进分级加载和地基沉降分析的分层总和分析的思想,结合增量广义虎克定律和Duncan-Chang模型,建立了以路基土体初始孔隙率、泊松比、粘聚力和内摩擦角等为参数的路基贯入荷载位移分析模型.基于上述静力贯入位移分析模型,根据实测路基静力贯入荷载位移曲线,引进自适应遗传模拟退火优化反演分析方法,建立了基于静力贯入试验的路基压实度检测方法,该方法不仅可以检测路基压实度,还可以测定路基土体其他物理力学参数,而且,该方法还具有检测速度快和效率高的特点.通过工程实例计算和与现有方法的对比分析,表明了本文方法的合理性与可行性.     

土石混合料压实特性的离散元分析

填料性质是影响土石混填路基压实效果的主要因素.本文用离散元程序PFC2D建立土石混合料振动压实模型,从颗粒粗糙度、颗粒刚度、最大粒径、含石量对土石混合料压实效果进行分析.结果表明:以压实度为指标控制土石混填路基压实质量时,必须用最大粒径、含石量对标准干密度修正.研究弥补了宏观试验无法反应的微观问题,对工程实践有重要的指导意义.     

关于土石混填路基填筑的探讨

托阿公路土石混填路基,在北疆属于地形复杂,施工难度大的地段,本文通过土石混填路基的探讨提出几点看法,谨供参考。     

土石混填体变形力学特性大型三轴试验研究

为了进一步研究土石混填体的变形力学特性,全面考虑含水量、含石量、岩性及土性等因素的影响作用,采用YS30-3型应力路径三轴剪切试验机,基于正交试验方法进行了一系列土石混填体大型三轴压缩研究.试验结果表明,在三轴受力条件下,土石混填体在低围压下的应变软化特征不明显,试样的粘聚力普遍较低而内摩擦角则比较高,且内摩擦角更容易受其他因素的影响而发生显著变化.含石量对土石混填体的抗剪强度影响程度最大,随试样中的含石量从25%增加到70%,其内摩擦角从34.54°近似线性增长至46.39°.含石量和围压分别是影响土石混填体体变特性最主要的内因和外因,即在含水率、岩性、土性相同的情况下,含石量越低试样高压剪缩性越明显,含石量越高其低压剪胀性越明显.     

重复列车荷载作用下多年冻土路基长期变形分析

在青藏铁路北麓河段选取素填土路基断面开展列车通过实时振动测试,得到车载作用下路基路肩处的加速度时程曲线,并将该动力荷载转化为作用在路基表面的等效均布荷载.基于冻土三轴流变实验结果,对典型的青藏铁路多年冻土路基进行了重复列车荷载作用下的蠕变分析,得到了机车荷载作用下冻土路基所产生的长期变形量,量化了该部分变形在路基总变形中所占比例.研究结果表明,机车荷载作用下路基两侧坡脚产生较大的剪应变,并且逐渐向上扩展,垂直方向变形占总变形量的10%左右.     

填方材料变形模量与压实度的关系

简便快捷、准确客观检测和监控填土压实度质量是工程施工与监理、工程建设与管理等追求的目标,变形模量作为一种路基强度指标,可以反映路基特性。采用落球式测试技术为手段,在相同碾压条件下,测试同类填方材料路基的变形模量与压实度,并对其进行函数拟合分析,研究填方材料的变形模量和压实度的内在关联,建立变形模量与压实度的关系模型,最后应用所得模型对填方工程质量进行监控、检测,并与传统的挖坑灌砂法对比验证,以明确变形模量与压实度的关系模型的可行性。     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

英文诗歌中的喻类修辞

为了有助于提高英文爱好者的个人情操、文化素养和学习兴趣,以及专业人员对英语学习和研究进行多途径的探索,本文通过一些精选诗歌的引证和分析,着重论述了喻类修辞法在英文诗歌中的运用其及效果。     

Man Is Unable to Change the Miserable Life——Analysis of the Arrangement of Four Characters in The Glass Menagerie

Tennessee Williams is considered as one of the most important American playwrights since World War II.The Glass Menagerie is his first successful drama,which describes a tragic situation of family and means to say that Man is unable to change the miserable life,no matter whatever means he try,This essay focuses on the analysis of the arrangement of the four main characters:Laura.Amanda,Jim and Tom to reveal the theme.Laura is fragile.Amanda is brave.Jim is vital.Tom is sensible.And all of them develop and try the different means to struggle against life,but fail tragically.With the evidence,the paper comes to conclusion naturally that Man is unable to change the miserable life,and he dooms to fail.     

Characterization of root-nodulating bacteria on Retama raetam in arid Tunisian soils

The aim of this study is to investigate the diversity of Retama raetam root-nodule bacteria isolated from arid regions of Tunisia. Twelve isolates, chosen as representative for different 16S rRNA gene patterns, were characterized by 16S rRNA gene sequencing and phenotypic analysis. Isolates were assigned to Sinorhizobium, Rhizobium and Agrobacterium. Symbiotic properties of Sinorhizobium and Rhizobium isolates showed a large diversity in their capacity to infect their host plant and fix atmospheric nitrogen. Strain RK 22 identified as Rhizobium was the most effective isolate.     

An Affordable Accurate Evaluation of the Binding Conformations Predicted by Molecular Docking Studies in Bio-System

正Recently,docking has been widely used to predict the binding-modes of protein-inhibitors,when the crystal complexes structure was absent.Most docking algorithms are able to generate a large number of probable conformations,it,however,is difficult to effectively evaluate these docking poses and identify the most reasonable bindingmode.In the present study,on the basis of the crystallographic data of human 3-hydroxy-3-methylglutaryl coenzyme     

WIMAX与WI-FI技术分析及联合组网

介绍了WiMAX与Wi-Fi两种无线宽带接入技术,并对两者之间的关系及相互之间的影响做了对比及分析,并对WiMAX的关键技术进行了详细说明,最后对两者的联合组网方式做了简单的探讨。