岩土力学近期发展浅议

本文对岩土力学研究中的几个主要方面作了简要的介绍与讨论,包括岩土介质的本构关系、 岩体断裂性质、节理与层面问题、现场测试、室内试验有待解决的问题、岩土介质与上部结构物的共同作用、环境岩土力学与工程、数值分析与计算机辅助设计以及岩土力学与工程中的不确定性问题.文中还对学科发展与工程应用、数值计算与数值模拟、研究方法与技术途径、新领域与学科之间的相互渗透以及岩土力学与工程当前的有利与不利之处分别作了简要的说明与讨论.     

关于两类环境问题的研究─21世纪中国东部主要工程地质课题初析

本文认为环境岩土工程问题与污染和生态破坏环境问题是等价的。所以,存在着两类同样重要的环境问题。关于两类环境问题的类型划分和内容,文中做了系统介绍和讨论。并着重对我国东部3个有重要意义的主要环境岩土工程问题进行了分析。     

城市地下工程中的环境岩土工程问题

近年来, 随着城市人口的急剧增长, 交通与住房拥挤状况日趋突出, 在我国一些大中城市中, 道路交通隧道、地铁工程、地下商城等地下工程建设项目在逐年增多。由于城市工程环境特殊性和地下工程的特点, 在其施工过程中经常出现基坑失稳 (明挖 )、地面沉降、岩溶塌陷、洞室失稳、巷道突水等多种环境岩土工程问题, 不仅严重影响地下工程建设和周围建筑物环境安全, 而且给国家造成重大经济损失。这一问题已引起岩土工程领域很许多专家的关注, 并成为该领域的研究热点。本文结合南京市区地下工程建设的实际情况, 探讨城市地下工程环境岩土工程问题的特点和形成机理, 并提出解决地下工程环境岩土工程问题的方法和建议。     

当前国际环境地质工程(环境岩土工程)研究的热点领域及其相关技术

当前环境地质工程(或称环境岩土工程)(EnvironmentalGeotechnology)国际学术讨论会的频繁召开, 反映了世界各国对解决环境问题的迫切愿望, 预示着一个世纪性的环境地质工程研究热潮已经到来。结合我国的国情分析这些会议所研讨的内容, 将有助于提高对当前环境地质工程热点研究领域的认识, 从而在解决国家所面临的环境问题及经济社会可持续发展中发挥应有的作用。本文是作者对当前国际环境地质工程(环境岩土工程)研究热点领域及其相关技术的集成。由于环境问题的广泛性, 对于国内的传统环境工程地质和地质灾害内容不加重复, 但它们同样重要。     

新世纪伊始中国工程地质回顾与展望

我国工程地质学经过 5 0年的工程实践和理论创新 ,已由条件工程地质学、问题工程地质学以及随着环境文明时代的到来向着环境和灾害工程地质学发展。近 10年来随着我国经济建设的快速发展 ,一批大型和特大型工程的兴建和城市化进程的加快 ,带来的地面变形、滑坡、环境恶化和全球悬河化等环境岩土工程问题 ,使工程地质地位和作用提高 ,学科在拓展。目前 ,我国已拥有一支能适应大规模经济建设需要并已走向世界的工程地质工作队伍 ,形成了具有我国自己特色的工程地质学科体系     

论两类环境和两类悬河问题的研究

分析认为环境问题有两类 :污染与生态破坏和环境岩土工程问题。悬河问题也有两类 :永久性悬河和暂时性洪水悬河。它们属于 2 1世纪我国将面临的主要环境岩土工程课题。本文就这些问题的基本概念和研究途径作一讨论.     

城市发展与城镇化——工程地质学的机遇与挑战

在城镇化全球规模的历史趋势和中国城市发展与城镇化历程及其特点分析的基础上,围绕城市岩土工程与地质环境系统,讨论了地质环境与城市规划、城市地下空间利用、城市生态与环境安全等领域工程地质研究发展的思路,强调了地质基础研究与多学科多源知识融合、多种技术集成的创新发展途径。     

济南市岩土地基工程地质环境质量分级与评价优势指标

随着城市化进程加快,济南市在城市建设中面临日益严重的环境工程地质问题。为了更好地服务于城市建设,做好岩土地基的工程地质环境质量评价与分区有重要实际意义。本文分析了济南市区的工程地质环境条件,研究了济南市区岩土地基工程地质环境质量评价模型与优势指标,并采用BP神经网络模型对济南市区的岩土地基工程地质环境质量进行评价与分级。     

工程地质与岩土工程

对于工程地质与岩土工程的两个概念进行了详细对比 ,指出他们的异同。指出工程地质是岩土工程的基础 ,岩土工程是工程地质的一个延伸     

福州轨道交通建设中的岩土工程问题

由于福州盆地工程地质条件的复杂性以及隧道工程的特殊性,在福州轨道交通建设过程中将遇到大量环境岩土工程问题。主要的环境岩土工程问题有:(1)隧道掘进范围内的承压含水层。承压含水层富水性、透水性强,由于开挖深度大,必须考虑下部承压水的影响,避免产生基坑突涌问题。砂砾卵石层直接覆盖于基岩裂隙热水上,受热水构造带高温热水的直接补给以及热传导,地下轨道交通建设对地热场是否存在影响以及地热对轨道交通的影响需要深入研究。(2)软土的大变形与低强度。导致地基失稳与土体结构强度破坏。(3)深大基坑开挖施工引发的可能灾变。基坑开挖易产生滑塌、流泥、突水(涌)、地表沉陷等问题,必须采取有效的支护措施,避免基坑失稳而影响工程安全及周边环境。对这些环境岩土工程问题,应加强勘察新技术的应用,查明建设场地岩土工程地质条件; 采用人工地层冻结法、桩基托换技术进行施工; 开发和利用适合本地区岩土条件的新技术、新工艺,如新型桩、新的止水、降水措施等基坑支护新技术,以及采用信息化施工新技术。     

地质工程监测信息系统开发

功能完善的地质工程监测系统在水电工程、环境工程及露天采矿工程等等中的重要性己日益显露出来。为此, 本文提出了地质工程监测信息系统的构想, 并从开发方法选择、功能需求分析、系统设计特征及系统开发实施四个主要方面, 对地质工程监测信息系统开发中若干重要问题进行了探讨。     

Boundary layer development of pulsatile blood flow in a tapered vessel

Assuming that the tapered angle is small,the problems of developing flow under unsteady oscillatory condition are studied in this paper.The formula of velocity distribution is obtained.The analyses for the results show that the blood flow in a converging tapered vessel remains a developing flow throughout the length,and the effects of tapered angle on the developing flow are increased with the increment of the tapered angle.     

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为快速开发水力学CAI软件－－水力学求解器,提出了BFB开发模式和积 木式结构相结合的开发方法. 这种开发方法的优点在于最大限度地利用现有源代码,便于软 件内容的扩展及多人协同工作, 软件界面友好,使用方便,满足水力学教学的要求.     

Numerical Simulation of Particle Dispersion in a Spatially Developing Mixing Layer

Although there have been several numerical studies on particle dispersion in mixing layers, most of them have been conducted for temporally evolving mixing layers. In this study, numerical simulations of a spatially developing mixing layer are performed to investigate particle dispersion under various conditions. The full compressible Navier--Stokes equations are solved with a high-order compact finite difference scheme, along with high-order time-integration. Accurate non-reflecting boundary conditions for the fluid flow are used, and several methods for introducing particles into the computational domain are tested. The particles are traced using a Lagrangian approach assuming one-way coupling between the continuous and the dispersed phases. The study focuses on the roles of the large-scale vortex structures in particle dispersion at low, medium and high Stokes numbers, which highlights the important effects of interacting vortex structures in nearby regions in the spatially developing mixing layer. The effects of particles with randomly distributed sizes (or Stokes numbers) are also investigated. Both instantaneous flow fields and statistical quantities are analyzed, which reveals essential features of particle dispersion in spatially developing free shear flows, which are different from those observed in temporally developing flows. The inclusion of the gravity not only modifies the overall dispersion patterns, but also enhances stream-crossing by particles. Received 7 June 2001 and accepted 19 February 2002     

计算动脉血管发展流动的新差分格式

在引用守恒型N—S方程和SIMPLE方法的基础上，对血管发展流动的控制方程提出了新的差分格式。算例结果表明：本差分格式对血管发展流动的数值研究是可行的。     

Preventing congenital anomalies in developing countries

The birth prevalence of congenital anomalies in developing countries is similar to that observed in developed countries. However, the health impact of birth defects is higher because of a lack of adequate services for the care of affected infants and a higher rate of exposures to infections and malnutrition. A number of successful measures for the prevention of congenital anomalies are being taken in a number of developing nations. Primary prevention programs are based on public education about preconceptional and prenatal risks. Prevention based on reproduction options includes teratogen information services and prenatal screening for fetal anomalies. In addition, programs for the detection of congenital malformations at birth, followed by early treatment, are contributing to secondary prevention. Prevention of congenital anomalies in the developing world requires: (a) good epidemiological data on the prevalence and types of birth defects and genetic disorders; (b) educating health professionals in the goals and methods of preventing birth defects at low cost but with high impact, and (c) expansion of family planning and improvement of antenatal care combined with educational campaigns to avoid the risks for birth defects. The basis for public health preventive measures should be the primary health care level. In a sizable proportion of developing countries, the stage is already set for these measures to be implemented. Required are education, political will, and proper organization and allocation of resources.     

An eigenfunction solution of entry flow in a semi-infinite pipe at low Reynolds numbers

The developing flow in a semi-infinite pipe is solved for by an eigenfunction method. The results are applicable to zero and low Reynolds number flows. The eigenfunction method yields a solution which accurately predicts overshoots in the axial velocity for small axial positions. Results are presented for both uniform and non-uniform inlet conditions. The latter condition has important implications for numerical simulations of the developing flow problem.This research was performed while Mr Benson was a graduate student at Clarkson College, Potsdam, NY, USA.     

Effects of viscous dissipation and boundary conditions on forced convection in a channel occupied by a saturated porous medium

Forced convection with viscous dissipation in a parallel plate channel filled by a saturated porous medium is investigated numerically. Three different viscous dissipation models are examined. Two different sets of wall conditions are considered: isothermal and isoflux. Analytical expressions are also presented for the asymptotic temperature profile and the asymptotic Nusselt number. With isothermal walls, the Brinkman number significantly influences the developing Nusselt number but not the asymptotic one. At constant wall heat flux, both the developing and the asymptotic Nusselt numbers are affected by the value of the Brinkman number. The Nusselt number is sensitive to the porous medium shape factor under all conditions considered.     

导弹水下发射燃气泡计算

采用一维非定常气流场模型和轴对称理想水流场模型，对水下发射导弹的尾部非定常燃气泡内外流场进行了耦合数值求解。考虑了高温燃气与水介质之间的传热、汽化等对泡内气体流动的影响，数值模拟了燃气泡的生长和脱落过程，揭示了燃气泡中气体流动的基本规律，计算了燃气泡发展对导弹所受水动力的影响。     

Calculation of two-dimensional shear-driven cavity flows at high reynolds numbers

The time-dependent Navier–Stokes equations are numerically integrated for two-dimensional incompressible viscous flow in a shear-driven square cavity. Using a time-splitting method and finite differences on a staggered mesh, the momentum and pressure equations are directly solved by a tensor product method where one finite difference direction is diagonalized by eigenvalue decomposition. The effects of increasing Reynolds number are studied and the developing boundary layer is captured by using a finely clustered mesh. At Re = 30000 the flow is in a continuously developing unsteady regime. Power spectrum plots indicate that the unsteady flow oscillates with one fundamental frequency and exhibits some characteristics of transition between laminar and turbulent states.