砂土

It also carries on four levels of single-factor laboratory experiments with three sample soils: clay, cohesionless soil and sandy soil, concerning three elements: cement mixture ratio, age, water content in order to find out the contractibility under different test conditions, and also the permeability of locking surface between cement soil and concrete.

试验选择粘土，粉砂土和粗砂土三种土质，采用室内试块试验的研究方法，选择水泥掺入比、龄期、含水量三种因素，分别进行了四种不同水平的单因素试验，研究水泥土在不同养护条件下的收缩性，通过水泥土和混凝土咬合面渗透试验来检验两者咬合面的抗渗性。

Based on definitions of stress and strain, and the D'Alembert's principle, stress and strain of soils at various depths were derived from the data of acceleration, displacement, as well as excess pore pressure measured in the test. The stress paths and stress-strain relationships of saturated sand during the shaking event, and their connection with development of excess pore pressure were revealed.

根据应力和应变的定义以及达朗贝尔原理，由试验观测的土体加速度、位移和孔隙水压力数据直接推导得到不同深度处砂土的应力和应变，揭示了振动过程中饱和砂土的应力路径和应力-应变关系演化过程，以及与超静孔隙水压力发展的联系。

The so called state-dependent dilatancy theory was suggested and applied in sand modeling.

本文就砂土的状态及其描述、剪胀理论的发展、砂土本构模拟等方面进行介绍。

The volumetric strain due to stress-dilatancy of sand is found to be composed of a reversible dilatancy component and an irreversible dilatancy component.

基于对较高精度的砂土扭剪试验成果的分析，表明砂土的剪胀是由一个完全可逆的体应变分量和一个不可逆的体应变分量构成的。

Through detailed analyzing some influencing factiors of sand liquefaction, seven parameters were selected as assessment indexes. They are earthquake magnitude, peak ground surface acceleration, standard penetration value, specific penetration resistance, relative compaction, average particle diameter, and water table. The extension assessment model has been established that was applied to assessment of sand liquefaction potential. The model had been trained by the historical data and has been assessed in virtue of sand liquefaction from the historical data by simulating, and got a excellent result. After introduction of the support vector machine theory, this paper established the assessment model of sand liquefaction based on the support vector machine, and assessed in sand liquefaction from virtue data of some fields in home and overseas with the tool Libsvm, which was programmed based on the support vector machine theory. And got a good coherency between the assessement results and the actual liquefaction.

在详细分析影响砂土液化因素的基础上，选取了震级M、地面最大加速度g_、标准贯入击数N_(63.5)、比贯入阻力P_s、相对密实度D_r、平均粒径D_(50)、地下水位d_w等7个参数作为评价指标，建立了砂土液化势的可拓评价模型，并对历史数据进行仿真评价，取得了较好的应用效果；在对支持向量机的理论进行介绍后，本文建立了基于支持向量机的砂土液化势评价模型，并利用在基于支持向量机理论的Libsvm软件，对若干国内外场地的现场实测数据进行了评价，评价结果与现场表现基本上一致。

Numerical simulation and shaking table tests for acceleration response of piles in liquefiable ground were performed under three earthquake events.

结果表明：三种地震输入下，自下而上沿桩-柱墩长度方向，加速度峰值放大系数变化基本一致且均出现在10～20s时段内，加速度时程曲线的形状也极其相似；压缩0.15g El Centro波输入下加速度反应在砂土层与黏土层过渡带有增大趋势、在地表则有一定程度减小，且压缩0.15g El Centro波较0.15g El Centro波输入下均偏小，0.15g El Cen-tro波输入下自下而上桩的加速度时程幅值和峰值放大系数的试验值、计算值均一直有较大幅度增大；0.5g El Centro波输入下，加速度时程幅值的计算值和试验值在桩折断位置之下一直增大、至砂土层与黏土层过渡带则大大减小，加速度峰值放大系数的试验值和计算值在砂土层与黏土层过渡带突变增大、而在地表则明显减小，且较0.15g El Centro波输入下桩的峰值放大系数要偏小。

The main achievements could be summarized as follows.1. The basic stress-strain characteristics and related physical mechanisms for sands under cyclic rotation of principal stress axes were investigated based on three kinds of drained tests including fixed principal stress axes, cyclic rotation of principal stress axes with magnitudes of principal stresses kept constant, and cyclic changes of principal stresses in both their axes and magnitudes. The main deformation behavior of sands with inherent anisotropy under cyclic rotation of principal stress axes with magnitudes of principal stresses kept constant was obtained in the following.

本文从试验研究、规律分析、数学建模和工程应用四个方面，对应力主轴循环旋转条件下砂土的变形特性进行了较为深入的研究，取得了如下主要研究成果：(1)基于对饱和砂土进行的主轴固定单调剪切、纯应力主轴循环旋转以及主应力幅值与应力主轴耦合循环变化的三类完全排水试验成果，分析和揭示了应力主轴循环旋转条件下砂土的基本变形规律，并探讨了其受力变形的内在机理。

The rate of wetting front advance and infiltration rate under certain ponded infiltration was significantly reduced by Sodium Polyacrylate , and as a result effectively reduced water in a sandy soil leaking to a deeper layer under the plough layer.

砂土的饱和导水率随着高分子化合物聚丙烯酸钠用量增加而降低，在恒定水头入渗条件下，聚丙烯酸钠降低了水分向深层运移的速度，同时降低了砂土的入渗速率，可以有效降低砂土水分的深层渗漏。

Numerical simulations by assemblies of circular panicles can qualitatively reflect the general characteristics of liquefaction behavior of sand. The interval effect of aspect ratio of elliptical panicle on the mechanical behavior of numerical sample is obtained, and the reason is related to the initial average co-ordination number. The regularity of evolution of fabric in the process of sand liquefaction under cyclic loading can be qualitatively achieved by using the numerical sample randomly mixed of panicles with different shapes. Numerical simulations can not only demonstrate the macro phenomenon of particle breakage, mostly importantly, it can also expose the evolution of particle breakage microscopically, and would contribute to further research of the micromechanics of particle breakage.

研究结果表明：Hertz-Mindlin非线性接触模型适用于变围压条件下砂土力学性质模拟；纯圆颗粒模拟能够定性地反映饱和砂土振动液化的一般规律；颗粒长短比变化对砂土力学性质的影响具有区间效应，其原因与粒间初始平均接触数有关；不同形状随机混合试样能够从定性规律上反映振动液化过程中砂土的细观组构演化规律；数值模拟不仅可得到颗粒破碎宏观响应，而且可以分析内部接触力变化和实现对粘结破裂位置的追踪，从而可进一步研究颗粒破碎细观力学机制。

The time from saturated soil moisture content to wilting percentage of Aeolian sandy soil, Loessial soil and Lou soil was extended by 244.72%,251.11% and 36.31% respectively when Sodium Polyacrylate was applied at the suggested dosage.

风砂土、黄绵土与塿土的蒸发强度随着高分子化合物聚丙烯酸钠用量增加而降低，聚丙烯酸钠用量为0.5%时，砂土、黄绵土与塿土10天累积蒸发量分别较对照降低了59.89%、48.92%与55.81%；综合考虑对土壤蓄水与蒸发能力的影响，聚丙烯酸钠用量为风砂土、黄绵土应控制在0.08%～0.2%，塿土中用量必须严格控制在0.2%左右；在上述用量条件下，风砂土、黄绵土、塿土从饱和含水量蒸发失水至凋萎含水量的时间分别被延长了244.72%、251.11%与36.31%左右。

If Pentium 4 used to be the master of all games built on Quake3 engine, now the situation has changed completely.

如果奔腾4使用的是掌握所有游戏建立在求苛刻的发动机，现在的情况已完全改变。

No, this is not what we mean by framing, although the principle is the same.

不，这不是我们所讲的框架的含义，尽管法则是一样的。