热力耦合作用下圆形水工隧洞围岩弹塑性解析解

为研究圆形水工隧洞围岩弹塑性区受力特点,基于Mogi-Coulomb强度准则和弹塑性理论,考虑温度和衬砌结构的影响,推导热力耦合作用下水工隧洞围岩应力、洞壁位移和围岩塑性区半径的解析解。依托新疆某高地温水工隧洞工程进行计算分析,对中间主应力系数、温度、混凝土强度、衬砌厚度和围岩应力分布及塑性区半径间的关系展开参数分析。结果表明：温度变化产生的拉应力会使衬砌结构对围岩支反力减小,围岩塑性区半径和洞壁位移有所增大,隧洞岩体稳定性变差;中间主应力系数b对岩体强度影响较大,b=0.5时围岩塑性区半径明显小于不考虑中间主应力时的塑性区半径;提高混凝土强度和增加衬砌厚度在初始阶段都能明显限制围岩塑性区发展,虽后续效果都不佳,但增大衬砌厚度更能限制围岩塑性区发展。     

渗流效应对基于广义非线性屈服准则洞室弹塑性解的影响

考虑渗流效应,基于广义Hoek-Brown非线性屈服准则,推导出圆形洞室围岩塑性区半径、洞壁径向位移和洞室周边径向应力的数值解.绘制在考虑渗流的情况下和基于广义Hoek-Brown屈服准则的不同围岩条件下,圆形洞室内外水头差h与R/e(R为塑性区半径,e为洞室半径)的关系曲线、围岩特性曲线和径向应力的分布曲线.研究结果表明:在水头差相同时,位于较差围岩中洞室的塑性区比位于较好围岩中洞室的塑性区发展快;在支护力相同时,支护结构对处于较差围岩中的圆形洞室洞壁位移约束效果较差;在围岩质量较差时,渗流效应对圆形洞室径向应力的影响比围岩质量较好时的影响大.     

基于蠕变终止轨迹的巷道围岩粘弹塑性分析

引入稳定巷道围岩中的峰值应力为一定围压下围岩的长期强度的观点,将巷道围岩分为弹、塑性区;考虑围岩流变、塑性扩容及中间主应力的影响,基于Drucker-Prager准则对圆形巷道围岩的弹塑性进行了分析,推导出相应的应力、位移及塑性区半径的解析解;考虑岩体特征值(E,μ)与时间和应力有关,基于西原模型采用Laplace变换法对所得结果进行了修正,得到围岩粘弹性位移解;在相关文献试验基础上,进行了实例计算并与ABAQUS模拟结果对比。结果表明:围岩流变特性对巷道变形及塑性区的扩展具有重要影响,以一定围压下围岩的长期强度为巷道围岩应力峰值,能够在一定程度上反映围岩流变特性对巷道围岩变形的影响,符合工程实际;粘弹性位移与数值模拟解吻合较好。本研究对巷道长期稳定性理论及地下巷道支护具有一定的参考意义。     

圆形巷道原岩应力对塑性区的影响规律研究

为研究塑性区围岩应力与原岩应力的关系,将巷道围岩分成塑性残余区、塑性软化区和弹性区,基于Mohr-Coulomb强度准则,考虑扩容和软化特性,计算出了塑性区应力和半径的解析式。通过算例分析了原岩应力对塑性区应力、应变和软化模量的影响。分析结果表明:原岩应力越大,软化区和残余区的范围越大;软化区某点应力减小,而残余区应力几乎不变;原岩应力对软化模量的影响与支护阻力相比小得多;塑性区的径向应变增长速度较环向应变快。研究成果为圆形巷道围岩稳定性和支护设计提供一定的理论依据。     

改进H-B准则的层状岩体隧洞塑性区半径与应力场分析

基于改进的各向异性Hoek-Brown(H-B)强度准则,推导得到层状岩体隧洞围岩塑性区应力场表达式,获得围岩塑性应力分布和塑性区半径解析解.与横观各向同性应力解对比,论述应力分布计算式的正确性与优越性,并分析层理面与最大主应力方向夹角β,地应力p_0,围岩单轴抗压强度,以及H-B强度准则经验参数mi对塑性区半径的影响规律.以片麻岩体隧洞为例,重点讨论文中解对β的敏感性.结果表明:当β=90°时,应力随着隧洞半径r增大而增大的速度最快;β对塑性区半径R_p的大小有重要影响.     

顾及沉积岩应变强化与扩容效应的围岩弹塑性力学状态理论分析

根据非关联流动法则与中主应力表达式,顾及沉积岩应变强化和扩容效应,推导基于幂强化-理想塑性本构模型和Drucker-Prager屈服准则的应力、位移、塑性区半径的解析解.将文中解、幂强化解、幂强化-理想塑性解进行比较,分析幂强化指数与扩容角对解析解的影响规律.结果表明:幂强化指数对围岩稳定性有较大的影响;扩容程度的变化对围岩应力和位移的影响随着扩容角及原岩应力的增加而增大;当隧洞围岩受到应变强化和扩容效应共同影响时,幂强化指数与扩容角越大,隧洞围岩位移越为敏感,对围岩稳定十分不利.     

基于双极坐标法浅埋圆形隧道围岩非线性弹塑性分析

考虑围岩的非线性特性,采用双极坐标系研究弹塑性半无限空间内浅埋隧道围岩应力分布和塑性区域。在连续、均匀和各项同性的无限半空间下建立浅埋隧道开挖模型,围岩求解问题可当作半无限平面问题,并且将平面依据双极坐标曲线划分。在地表均布荷载和隧道径向支护力作用下,基于广义Hoek-Brown强度准则推导出半无限空间内水平圆形隧道围岩的弹塑性应力解析解以及塑性半径、塑性区域范围和隧道临界支护力计算方法。最后,通过数值计算,分析地质强度指标、内部支护力、地表荷载和隧道埋深的变化对浅埋隧道围岩的塑性半径、塑性区域形状和应力分布的影响规律。通过与其他基于线性强度准则下的应力计算方法进行对比,验证本文方法的有效性。之后的结果显示,两种准则计算结果差距十分小。     

考虑材料软化的洞室围岩弹塑性分析的统一解

基于统一强度理论,考虑岩土材料的软化特性,用弹性塑性软化塑性残余三线性应力应变模型推导出了洞室围岩塑性残余区半径、塑性软化区半径、洞周边位移、围岩内任一点应力及围岩压力的解析计算公式。同时给出了洞室围岩所处应力状态的判别式。得出的解答具有广泛意义。著名的Kastner公式、Airey公式均为本文的特例。通过实例分析了软化及不同强度模型对计算结果的影响。     

考虑水-力耦合效应时软化围岩解析

基于线性Mohr-Coulomb(M-C)强度准则,改进考虑水-力耦合作用下应变软化围岩深埋圆形隧道的应力与位移求解的逐步位移法。该方法全面考虑水-力耦合作用下围岩强度和变形参数的劣化、剪胀角和塑性区内弹性应变的变化。基于平面应变的假设和改进的逐步位移法,将整个塑性区分为n个同心圆环,以弹塑性交界面处的应力应变作为塑性区的初始值,获得塑性区内的应力及位移解。同时,对水-力耦合作用下的强度及变形参数进行分析。研究结果表明:在考虑水-力耦合作用下,应力减小,收敛和塑性半径均变大,位移与塑性半径提高幅值分别为27.00%和3.17%。     

采用统一强度理论的锚喷支护围岩弹塑性统一解

基于双剪统一强度理论,结合点锚式锚杆锚喷支护的力学机理,导出双向等地应力情况下无限均匀介质中锚喷支护圆形洞室围岩应力场、位移场及塑性区半径解析解.分析强度理论参数b值对弹性区和塑性区应力、位移的分布特点的影响,以及锚喷支护对塑性区半径影响的变化趋势.结果表明:与Morhr-Coulomb强度理论结果相比,隧道轴向应力和...     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.     

Tracking data management using topology of moving object database system for moving object constrained trajectory in LBS application

Advances in wireless technologies and positioning technologies and spread of wireless devices, an interest in LBS (Location Based Service) is arising. To provide location based service, tracking data should have been stored in moving object database management system (called MODBMS) with proper policies and managed efficiently. So the methods which acquire the location information at regular time intervals then, store and manage have been studied. In this paper, we suggest tracking data management techniques using topology that is corresponding to the moving path of moving object. In our techniques, we update the MODBMS when moving object arrived at a street intersection or a curved road which is represented as the node in topology and predict the location at past and future with attribute of topology and linear function. In this technique, location data that are corresponding to the node in topology are stored, thus reduce the number of update and amount of data. Also in case predicting the location,because topology are used as well as existing location information, accuracy for prediction is increased than applying linear function or spline function.