液化地基的评价及处理的体会

合理评价液化地基及采用科学的处理方案对工程建设有重要意义，总结了影响地基液化的主要因素及液化判定的一般方法，提出了一种新的液化判定方法——归一法。结合实例就液化地基的设计与处理谈了一些体会。     

Simplified discrete systems for dynamic analysis of structures on footings and piles

A simplified discrete system in the form of a simple oscillator is developed to simulate the dynamic behavior of a structure founded through footings or piles on compliant ground, under harmonic excitation. Exact analytical expressions for the fundamental natural period and the corresponding damping coefficients of the above system are derived, as function of geometry and the frequency-dependent foundation impedances. In an effort to quantify the coupling between swaying and rocking oscillations in embedded foundations such as piles, the reference system is translated from the footing–soil interface to the depth where the resultant soil reaction is applied, to ensure a diagonal impedance matrix. The resulting eccentricity is a measure of the coupling effect between the two oscillation modes. The amounts of radiation damping generated from a single pile and a surface footing are evaluated. In order to compare the damping of a structure on a surface footing and a pile, the notion of static and geometric equivalence is introduced. It is shown that a pile may generate significantly higher radiation damping than an equivalent footing, thus acting as an elementary protective system against seismic action.     

动三轴试验固结时间对动剪切模量比和阻尼比影响的初步分析

动三轴试验是将试样在轴对称的三轴应力下进行固结,在不排水条件下进行的振动试验,同时可测定土样的动剪切模量比和阻尼比。土的动剪切模量比和阻尼比是土动力学特性的2个重要参数,在工程场地地震安全性评价工作和土层地震反应分析中不可缺少。为了减少工期,提高工效,及时而又准确地提交报告,我们结合自己多年的土工试验经验,对可塑状态以上的粘性土试样进行了缩短固结时间的对比试验,并得到理想的试验结果。     

固结比对土最大动剪切模量的影响

采用共振柱试验方法,研究了固结比对土最大动剪切模量的影响并给出了土最大动剪切模量的建议公式。通过对砂土、粉质黏土和粉土的系统试验,提出了不同固结比下土最大动剪切模量与固结比kc-1呈指数形式的增长模式,不同于Hard in公式最大动剪切模量与固结比kc呈直线形式的增长模式。同时给出了计算不同固结比下砂土、粉质黏土和粉土最大动剪切模量的建议公式,并与Hard in公式进行了对比,结果表明,固结比对土最大动剪切模量影响程度明显比Hard in公式要大,固结比对粉质黏土和粉土最大动剪切模量的影响程度要比对砂土的影响程度更大。     

Coupled consolidation of a porous medium with a cylindrical or a spherical cavity

This paper presents a theoretical approach to analyse coupled, linear thermoporoelastic fields in a saturated porous medium under radial and spherical symmetry. The governing equations account for compressibility and thermal expansion of constituents, heat sink due to thermal dilatation of water and thermal expansion of the medium, and thermodynamically coupled heat–water flow. It has been reported in the literature that thermodynamically coupled heat–water flows known as thermo-osmosis and thermal filtration have the potential to significantly alter the flow fields in clay-rich barriers in the near field of a underground waste containment scheme. This study presents a mathematical model and examines the effects of thermo-osmosis and thermal-filtration on coupled consolidation fields in a porous medium with a cavity. Analytical solutions of the governing equations are presented in the Laplace transform space. A numerical inversion scheme is used to obtain the time-domain solutions for a cylindrical cavity in a homogeneous or a non-homogeneous medium. A closed form time-domain solution is presented for a spherical cavity in a homogeneous medium. Selected numerical solutions for homogeneous and non-homogeneous media show a significant increase in pore pressure and displacements due to the presence of thermodynamically coupled flows and a negligible influence on temperature. © 1998 John Wiley & Sons, Ltd.     

一种亮星识别算法及其在天文定向中的应用

基于全站仪对任意亮星的观测采样,提出了一种利用高度角序列和水平角速率进行联合匹配的任意亮星识别算法。通过引入天体地平坐标计算程序,算法可正确辨别行星和恒星。本文分析了任意亮星高度角和水平角速率的观测误差和计算误差,以此给出了匹配阈值条件的设定依据,并在此基础上制定了有效的匹配策略。仿真计算及实际观测试验均表明,该算法具有100%的识别成功率,远优于现有算法。将此算法应用于任意亮星天文定向,定向结果的内符合精度达到2″,外部检核精度达到1.6″。采用多颗任意亮星进行定向,可有效减弱由测站位置误差引入的定向系统误差,提高绝对定向精度。本文提出的天文定向适用于多云及雾霾天气。     

柏井采空区地基注浆加固技术

通过目前国内外现有资料的对比研究，对严重影响石太高速公路修建和运营的柏井采空区采用压力注浆的方法，充填采空区上覆的裂隙冒落带，以达到加固地基的目的。灌注材料选用水泥和粘土，水固比为１：１．５，依据地面构造物不同，在桥涵地段采用１：０．８：０．７（水：水泥：粘土，下同）的配比，在边坡地段采用１：０．５：１的与比，在一般路段采用１：０．３：１的配比，灌注浆液的结石体在采空区及上覆的裂隙冒落带中充填率达     

碎石桩加固双层地基固结简化分析

碎石桩复合地基在工程上的应用非常广泛,其应力应变性状的研究已很深入,固结问题也得到了不同程度的研究,但已有的解析式大多较复杂,工程中难以应用。将桩间土径向整体作为一个研究对象,从而避开单独考虑因施工造成的涂抹作用的影响,根据排水量与体变等效原理,用平均超孔隙水压力的概念推导出碎石桩加固双层地基简化的固结计算式。由该方法可直接得到碎石桩和桩间土不同深度的平均超孔隙水压力和平均固结度,也可计算复合地基整体固结度。所推得的解析式简洁,且实用性强。     

动力排水固结前后软土微观结构分析

通过液氮冷冻干燥制样技术制备饱和软土试样,借助扫描电子显微镜技术,得到经室内动力排水固结前后土样的微观结构图像,用编制的计算机程序分析其微观结构参数变化。通过比较试样的孔隙个数、总面积、总周长、面积分级、平均孔径、形状系数、圆度和各向异性率、分形维数,研究了在动力排水固结作用下土体微观结构在垂直向和水平向发生的变化。