Porothermoelastic analyses of anisotropic hollow cylinders with applications

It has been known that material anisotropy and thermal stresses affect borehole stability significantly. Aiming at the experimental studies associated with borehole stability in anisotropic (transversely isotropic) poroelastic materials subject to non‐isothermal conditions, this paper details and applies an anisotropic porothermoelastic solution to an unjacketed hollow cylinder in a triaxial set‐up. Numerical analyses are presented to demonstrate thermal and material anisotropy effects on the pore pressure and the stress concentrations in and around the geometry of a hollow cylinder subjected to thermal and stress perturbations. Copyright © 2004 John Wiley & Sons, Ltd.     

地震主应力方向的附加潮汐应力计算及其对发震断层的作用方式研究

通过对地震震源处沿主压应力P轴和主张应力T轴方向的附加潮汐应力分量的计算，在岩石力学莫尔－库化准则的基础上分析了附加潮汐应力对发震断层的作用方式。分析和计算表明，对发震断层有促滑作用的附加潮汐应力作用方式分增压型和减压型，增压型潮汐应力增大断层面上的正压力和剪应力，促使断层达到破裂滑动条件，减压型潮汐应力在一定条件下能降低断层面上的破裂滑动强度，同样能促使断层的运动。计算实例显示，大部分发震断层受到了附加潮汐应力的增压型或减压型促滑作用。     

湘西花垣—茶洞断裂的活动期次与运动特征

花垣—茶洞断裂带位于湖南西部,为松桃—大庸深断裂的分支,是松桃—大庸断裂北段的一部分。通过对断裂带两侧的野外基础特征、节理发育处的测量统计、擦痕与共轭节理的应力分析以及断裂带两侧的深部钻孔勘探揭露,得出花垣—茶洞断裂带的活动至少有2个期次:一期为北东向南西向的左行剪切走滑;另一期为断裂带北侧的地层下滑,下滑距离约为550~700 m。     

绿潮生物学机制研究

绿潮发生机制极其复杂,但其核心机理是绿潮暴发时漂浮"藻席"中的浒苔快速形成巨大生物量,涉及浒苔生物学过程对环境的响应及其生理生化基础。为此,本文在已有研究报道的基础上,对浒苔生活史研究进行了充分的理论补遗;分析了漂浮"藻席"中浒苔生长与繁殖过程,认为该过程是绿潮生物量形成的关键;阐述了浒苔孢子囊形成是对富营养化背景下海水溶解无机氮(DIN)中硝态氮高占比的响应,认为一氧化氮分子可促进浒苔营养细胞向孢子囊的转化;解析了浒苔细胞对逆境因子的响应途径与机制。基于已有的研究成果,本文对浒苔引发绿潮的生物学过程进行了理论推定。人为或自然因素使固着浒苔处于漂浮状态,形成小规模"藻席";富营养化背景下海水DIN中硝态氮占比的升高赋予了浒苔巨大的繁殖潜能,漂浮过程溶解无机碳(DIC)"充裕"和"不足"两个阶段的交替以及食藻动物啃食产生的藻片段使孢子囊形成比例大幅提升;孢子原位萌发等使释放的孢子在"藻席"中获得了附着基,个体数目随之指数增长;结合漂浮浒苔的高生长速率,"藻席"规模不断扩大,短时间内形成巨大生物量。同时,本文还对今后的绿潮研究提出一些建议,认为啃食动物在浒苔生物量消长过程中发挥重要作用,在漂浮"藻席"系统中扮演着"生态引擎"的功能,同时系统阐明浒苔孢子的原位萌发等现象的生物学机理应该是未来绿潮的重要研究内容。     

An integrated three-dimensional model of wave-induced pore pressure and effective stresses in a porous seabed: II. Breaking waves

The evaluation of the wave-induced liquefaction potential is particularly important for coastal engineers involved in the design of marine structures. Most previous investigations of the wave-induced liquefaction have been limited to two-dimensional non-breaking waves. In this paper, the integrated three-dimensional poro-elastic model for the wave-seabed interaction proposed by [Zhang, H., Jeng, D.-S., 2005. An integrated three-dimensional model of wave-induced pore pressure and effective stresses in a porous seabed: I. A sloping seabed. Ocean Engineering 32(5/6), 701–729.] is further extended to simulate the seabed liquefaction potential with breaking wave loading. Based on the parametric study, we conclude: (1) the liquefaction depth due to breaking waves is smaller than that of due to non-breaking waves; (2) the degree of saturation significantly affects the wave-induced liquefaction depth, and no liquefaction occurs in full saturated seabed, and (3) soil permeability does not only significantly affect the pore pressure, but also the shear stresses distribution.     

A solution to estimate the total and effective stresses in backfilled stopes with an impervious base during the filling operation of cohesionless backfill

Mining backfill is commonly used in underground mines. A critical concern of this practice is to evaluate the pressures and total stresses in backfilled stopes to ensure a safe and economic design of barricades, constructed to retain the backfill. When a slurried backfill is placed in a mine stope, excess pore water pressure (PWP) can instantaneously generate and progressively dissipate. The dissipation of the excess PWP and consolidation lead to the development of effective stresses, which in turn lead to an arching effect in the backfilled stope. Until now, arching effect has been largely considered for stress estimation in dry or submerged backfill. The former corresponds to the final state at the end process of the drainage and consolidation of the backfill with a pervious while the latter with an impervious barricade. However, previous studies have shown that the most critical moment for the stability of barricades is during the stope filling. Therefore, the design of barricades requires a proper estimation of the pressure and total stresses during the filling operation. This in turn needs joint consideration of the arching effect and consolidation of the backfill. In this paper, a new solution is developed to evaluate the pressures and stresses in backfilled stopes during the filling operation of cohesionless backfill by considering the self-weight consolidation and arching effect. The proposed solution is validated by numerical modeling with Plaxis2D. It can thus be used to evaluate the pressures and stresses in backfilled stopes during the stope filling with an impervious barricade.     

基于路基土蠕变效应的路基预应力损失模型研究

新型预应力路基技术可用于整治路基病害或强化既有线路基,研究其预应力损失规律对保障预应力路基工程的长期安全具有重要意义。基于弹性理论提出了预应力路基侧压力板与路基边坡接触面中心点后方水平路径上附加应力的计算方法,分析表明该特征路径上水平附加应力随距板−土接触面中心点距离的增加呈现良好的指数函数衰减关系。基于水平附加应力的指数函数扩散规律及路基土的蠕变行为,推导了路基土的蠕变变形计算公式。进一步基于蠕变变形与预应力钢筋回缩变形的协调性,建立了路基预应力的损失模型和计算方法,并结合FLAC3D数值仿真开展了对比分析。研究表明：钢筋预拉力损失的理论预测曲线与数值仿真曲线吻合良好,二者偏差不足5%,论证了路基预应力损失模型的有效性;钢筋预拉力可在锚固后的60 d内达到稳定,且预拉力的稳定值可达其初始值的85%～90%,说明新型预应力路基技术可为路基土提供相当可观的稳定附加围压,从而通过改善路基土的应力状态达到强化路基的目的。     

近底层潮流速分布模式比较

考虑到潮流运动的非恒定性和非线性特征,基于潮流雷诺应力分布式,应用Prandtl混合长度和von Karman自相似理论,并结合潮流运动方程,推导了近底层潮流速垂向分布的双对数模式.然后,将该分布模式应用于英国大陆南部西Solent水道和江苏岸外西洋海域流速的实测资料,并与对数线性分布的计算成果相比较,获得了比较满意的结果.最后,对几种分布模式进行了讨论和比较,结果表明:在近岸水域采用对数或对数线性流速分布模式计算摩阻流速和粗糙高度往往会带来较大的偏差,双对数模式能使计算的结果更为合理.     

江西金山金矿成矿深度研究

构造附加静水压力的研究是构造物理化学研究的重要内容。本文运用构造物理化学的基 本理论，研究了江西金山金矿赋矿韧性剪切带的构造附加静水压力，测算了金山金矿的成矿深度。 研究表明，金山金矿的成矿深度在 ３１００～４３００ｍ左右，这对进一步在该区的找矿勘查工作具有 指导意义。     

条形均布荷载下横观各向同性弹性地基中附加应力的分布规律

本文评述了条形均布荷载下横观各向同性弹性地基中附加应力的诸户［２］解析解和近似解，并提出了笔者的近似简化公式，该公式简明地显示出附加应力在分布规律上与各向同性地基之异同点，可供工程界方便地加以利用。