CFG短桩复合地基技术用于高层建筑地基处理的探讨

阐述了ＣＦＧ短桩复事地基技术的特点及应用范围,并列举了２个具体的工程实例,经过实践验证该技术是一项省钱、施工质量容易得到保证且能满足复合地基承载力及最终沉降量要求的新技术。探讨了ＣＦＧ短桩复合地基设计中的几个理论问题,产提出了该项技术的进一步研究方向。     

高压旋喷技术在基坑护壁与止水工程中的应用

长沙天都大厦工程围护墙先后采用2套方案施工,实践证明,采用高压旋喷单管双液分喷法具有设备简单;投资少;操作容易,施工速度快;桩间搭接严密,固结体强度高;适用范围广等优点,尤其在处理软弱地基、基坑支护和止水工程中显示出有效性、可靠性和优越性。该方法再经进一步完善,将具广阔的推广前景。     

双层地基水平受荷桩受力变形分析

基于双层地基中的水平受荷桩的特性,对其受力变形进行了分析。将水平受荷桩视为竖直放置的弹性地基梁,基于Winkler弹性地基梁理论,考虑桩土共同工作得到水平受荷桩位移控制微分方程及其幂级数解答,进而根据内力与位移的连续条件得到了由桩顶受力及变形条件表示任一深度处桩身的水平位移、转角、弯矩及剪力的计算矩阵表达式。通过一具体算例将幂级数解计算结果与《公路桥涵地基与基础设计规范》推荐的简化计算公式计算结果进行了比较。结果表明：当第1层地基土的厚度在某一定值时,《规范》简化计算方法所得结果与幂级数解接近;但当层厚不在该值附近时,两个方法计算结果存在差异。     

Influence of condensation and latent heat release upon barotropic and baroclinic instabilities of vortices in a rotating shallow water f-plane model

Analysis of the influence of condensation and related latent heat release upon developing barotropic and baroclinic instabilities of large-scale low Rossby-number shielded vortices on the f-plane is performed within the moist-convective rotating shallow water model, in its barotropic (one-layer) and baroclinic (two-layer) versions. Numerical simulations with a high-resolution well-balanced finite-volume code, using a relaxation parameterisation for condensation, are made. Evolution of the instability in four different environments, with humidity (i) behaving as passive scalar, (ii) subject to condensation beyond a saturation threshold, (iii) subject to condensation and evaporation, with three different parameterisations of the latter, are inter-compared. The simulations are initialised with unstable modes determined from the detailed linear stability analysis in the “dry” version of the model. In a configuration corresponding to low-level mid-latitude atmospheric vortices, it is shown that the known scenario of evolution of barotropically unstable vortices, consisting in formation of a pair of dipoles (dipolar breakdown) is substantially modified by condensation and related moist convection, especially in the presence of surface evaporation. No enhancement of the instability due to precipitation was detected in this case. Cyclone-anticyclone asymmetry with respect to sensitivity to the moist effects is evidenced. It is shown that inertia-gravity wave emission during the vortex evolution is enhanced by the moist effects. In the baroclinic configuration corresponding to idealised cut-off lows in the atmosphere, it is shown that the azimuthal structure of the leading unstable mode is sensitive to the details of stratification. Scenarios of evolution are completely different for different azimuthal structures, one leading to dipolar breaking, and another to tripole formation. The effects of moisture considerably enhance the perturbations in the lower layer, especially in the tripole formation scenario.     

On the solar cycle dependence of winds and planetary waves as seen from mid-latitude D1 LF mesopause region wind measurements

At the Collm Observatory of the University of Leipzig LF D1 low-frequency total reflection nighttime wind measurements have been carried out continuously for more than two decades. Using a multiple regression analysis to derive prevailing winds, tides and the quasi-2-day wave from the half-hourly mean values of the horizontal wind components, monthly mean values of mesopause wind parameters are obtained that can be analysed with respect to long-term trends and influences of solar variability. The response of the prevailing wind to the 11-year solar cycle differs throughout the year. While in winter no significant correlation between the zonal prevailing wind and solar activity is found, in spring and summer a negative correlation between the TWC can be seen from the measurements. This is connected with stronger vertical gradients of the zonal prevailing wind during solar maximum than during solar minimum. Since the amplitude of the quasi-2-day wave is dependent on the zonal mean wind vertical gradient, this is connected with a positive correlation between solar activity and quasi-two-day wave activity.Paper Presented at the Second IAGA/ICMA (IAMAS) Workshop on Solar Activity Forcing of the Middle Atmosphere, Prague, August 1997     

带桩筏基系统的弹塑性分析与设计方法研究

采用ABAQUS有限元程序中的线性扩展D-P模型对带桩筏基下的地基土进行弹塑性模拟,建立了带桩筏基系统的ABAQUS程序三维有限元模型。经比较各种桩、筏基础的内力与沉降关系计算结果,得到了带桩筏基的一些工作特性。在此基础上结合《建筑地基基础设计规范》(GB5007-2002),改进了传统的复合桩基设计方法,讨论了“三阶段”设计理念的可行性,并将其应用于工程实例。分析结果表明,改进的复合桩基设计方法和“三阶段”设计方法较常规设计方法更加经济合理。     

等截面单桩抗拔承载性状试验研究

在基坑中对等截面单桩进行了抗拔静载试验，在桩身设置应变式钢筋计，成功测得桩身各截面的应变数据。分析试验所得数据，对试验抗拔桩抗拔系数的取值、侧摩阻力的发挥、混凝土桩身的开裂等进行了探讨，相应给出了抗拔桩的设计建议。     

对碎石桩法加固软土地基效果的分析

通过大量的碎石桩工程资料,分析了碎石桩法对杂填土,素填土和亚粘土,粉砂和轻亚粘土,粘土,淤泥质土和淤泥的加固效果。     

长乐-南澳韧性剪切带走滑特征探讨

长乐-南澳韧性剪切带可能是在碰撞造山缝合带基础上发育的,其走滑特性严格受闽台微大陆与闽浙中生代火山弧碰撞过程中碰撞动力学的制约。岩石韧性组构和糜棱岩变形的微构造研究表明,碰撞前期走滑为左行。在早垩世晚期(100-120Ma)的主碰撞期和以伸展作用为主的碰撞后期,该带以右行为主,这种右行走滑一直持续至今。发育韧性剪切带的闽台微大陆(或称平潭-东山带)原始位置可能比现今更靠南,这是属于几百公里的漂移位移而不是剪切位移。