This paper presents a model-based approach to determine dielectric constants from time domain reflectometry TDR measurement in highly conductive soils. It makes use of information contained in the TDR signal from the reflection at the surface of the soil rather than the reflection from the end of the probe. The TDR method is widely used to determine the volumetric water content of soils. Commonly used information from the TDR signals includes the apparent dielectric constant and the electrical conductivity. The apparent dielectric constant is generally measured by analyzing the travel time of electromagnetic waves reflected from the end of the soil probe. In soils with high electrical conductivities, the attenuation of the signal can eliminate the reflection from the end of the probe, which limits the application of TDR to these materials. A simplified frequency-independent dielectric model is utilized to invert the dielectric constant from the reflected signals at the soil surface. Results indicate that the dielectric constant can be determined with reasonable accuracy by the proposed approach for soils with high electrical conductivity, where the conventional travel time analysis fails due to significant signal attenuation.

According to the results of cyclic triaxial tests on Hangzhou sands, a correlation is presented between liquefaction resistance and elastic shear modulus. Material-dependent but independent of confining stress, shows the linear relation of (sd/2)1/2 with Gmax. For its application to different soils, a method proposed by Tokimatsu [Tokimatsu K, Uchida A. Correlation between liquefaction resistance and shear wave velocity. Soils Found 1990: 30 (2):33-42] is utilized to normalize the shear modulus with respect to minimum void ratio. A simplified equation is established to evaluate the liquefaction potential by shear-wave velocity. The critical shear-wave velocity of liquefaction is in linear relation with 1/4 power of depth and the peak horizontal ground surface acceleration during earthquakes. The equation proposed in this paper is compared with previous methods especially the procedure proposed by Andrus [RD Andrus, KH Stokoe. Liquefaction resistance of soils from shear-wave velocity. J Geotech Geoenviron Eng 2000: 126 (11): 1015-25]. The results show its simplicity and effectiveness when applied to sands, but more validation or modification is needed for its application to sand with higher fines content.

城市建设的开展和城市用地的紧张，使得地铁隧道附近往往布置新的建筑，对临近地铁隧道产生不利的影响。建立了地面新施工荷载对地铁隧道的影响分析计算模型，并采用有限差分法进行了求解。研究了荷载位置、隧道埋深、隧道直径以及不同土质对隧道沉降和内力的影响。成果可以为地铁隧道的保护提供一定的依据。

为更全面地分析桩承式路堤各组成部分的工作机理，降低计算复杂度，提出了一种综合考虑路堤填料中的土拱效应和桩土的荷载传递性状的解析解法。该解析法将桩承式路堤各组成部分看作一个整体，以桩、土和路堤三者之间的静力平衡为基础，建立了桩和土体位移的基本微分方程，通过考虑应力和变形的协调条件，获得了桩身轴力、桩间土应力、桩侧摩阻力、桩和土体沉降等的解析解，并研究了置换率、桩身模量、桩径、桩端土刚度和桩侧摩阻力发挥系数对沉降和荷载分担比等的影响。与丁程实测数据的对比结果表明，该解析法具有计算过程比较简单，计算结果与实测结果比较一致的特点。

微型桩（Micropile）和常规钻孔灌注桩相比，具有单位体积混凝土承载力高、施工场地小、适用各种类型的土、布置形式灵活等特点，可以用做输电线路杆塔基础。本文通过软土地基上微型桩的单桩、群桩抗压和抗拔现场试验，研究其荷载-沉降特性、群桩效应、施工工艺等，以期为微型桩的设计和施工提供依据。试验结果认为：单桩荷载-沉降曲线是缓变型，属摩擦桩，可以以20mm沉降量对应的荷载作为桩的极限承载力；可以以20mm～30mm上拔量对应的上拔荷载作为单桩极限上拔荷载；斜桩可以更好地承担上拔荷载。

In this paper the differential quadrature method (DQM) is introduced into the analysis of one-dimensional nonlinear consolidation of multi-layered soil with partially drained boundaries and arbitrary loading condition. The effect of initial effective stress distribution is taken into account. The convergence and accuracy study shows that the DQM is able to give highly accurate and stable calculations. Due to the uniform matrix structure of the solution, DQM is easy to program, and also various complicated factors of the consolidation problem can be considered.

作为一种经济、有效的软土地基处理方法，桩承式加筋路堤在国内外已开始使用。把单桩处理区域及上部路堤等效为圆桩体，采用弹塑性有限元法分析了瞬时加载后地基中超静孔隙水压力的分布特征及消散过程，研究了加筋格栅的受力和路堤的沉降特性等，分析了桩长、桩间距及桩托板大小对桩体荷载分担比和路堤沉降的影响。研究结果表明，打桩后桩体所受荷载向下传递，地基中的初始最大孔隙水压力出现在桩端以下土层。打穿软土层情况下，路堤的沉降量决定于浅部桩间土的压缩，而未打穿情况下，路堤的沉降量决定于桩端以下软土层的压缩。桩长是控制路堤沉降的最主要因素，其次是桩间距和桩托板尺寸。最后对一个工程实例进行了分析。

针对桩承式路堤工作性状比较复杂、对路堤—桩—土之间共同工作机理的认识还不是十分清楚的问题，建立了考虑土—桩—路堤变形和应力协调的平衡方程，分析了三者协调工作时路堤、桩、土的荷载传递特性，获得了路堤的土拱效应、桩土荷载分担、桩和土的沉降等结果。将本文的方法与弹塑性有限元计算结果进行了对比，验证了该计算模型的合理性，同时应用所提出的方法，对杭甬高速公路拓宽工程进行了分析。

由于多层地基的一维非线性固结问题求解的复杂性，其解析解很难求得。本文基于Davis和Raymond一维非线性固结理论，利用DQM（DifferentialQuadratureMethod）推导了初始有效应力沿深度变化、任意边界条件、任意荷载作用下成层地基一维非线性固结的统一表达式，求得了孔压、有效应力和平均固结度的解答。通过解的收敛性分析讨论了DQM解的有效性。由于DQM解对于固结问题各种复杂条件具有统一的矩阵表达式，更便于编程计算和工程应用。最后，用本文解答对三层地基一维非线性固结问题进行了讨论。

软土地基上高速公路的拓宽建设是高速公路工程中的重要课题。本文以杭甬高速公路拓宽为背景，分析了拓宽路堤附加应力对老路堤的影响，基于摩尔–库仑模型，研究了老路堤和拓宽路堤的沉降变形规律，并与实测结果作了对比。拓宽路堤作用下，新老路堤将产生不均匀沉降，路面产生拉应力。拓宽路堤路面铺设时间应以新老路堤工后差异沉降大小为控制标准。