高强轻集料混凝土工作性能优化的试验研究

以分层度、坍落度、扩展度为新拌混凝土工作性能的评价指标,研究了矿物掺合料、砂率、增粘剂和减水剂对高强轻集料混凝土(LWAC)工作性能的影响.结果表明:增粘剂、减水剂是影响LWAC工作性能的主要因素,矿物掺合料、砂率对LWAC工作性能的影响则较小;在相同条件下,复掺减水剂和增粘剂比单掺减水剂更能改善轻集料混凝土的匀质性,同时对抗压强度也有所提高.最后提出了高强轻集料混凝土工作性能优化的试验配合比.     

Wind tunnel modeling of hourly observed atmospheric diffusion by oscillating blade cascade

Horizontal plume spread increases greatly with averaging time. For hourly averaging, plume spreads are much greater in the horizontal direction than in the vertical. The ratio of horizontal to vertical spread was found to be as large as 6. Conventional method cannot reproduce such anisotropic diffusion characteristic in wind tunnel experiments. The author has developed an oscillating blade cascade as a solution to the problem. Since the blade cascade generates strong secondary flow in the test section, a horizontal wind fluctuation of more than 11° has been achieved, which is similar to the standard deviation of wind direction averaged over 1 h under neutral condition.Distributions of mean wind velocity, turbulence intensity, and spectral structures were also similar to those observed in the atmospheric boundary layer.Hourly-averaged plume spread in horizontal and vertical directions could be simulated in the wind tunnel on 1:5000 scale, with appropriate selection of random motion amplitude of the blade cascade and ground roughness arrangement. Thus, the oscillating blade cascade method is useful to model large-scale plume diffusion from a continuous source such as thermal power plant stacks.     

影响复合地基应力扩散的因素

采用有限元对复合地基的应力扩散性质进行了分析。计算结果表明 ,复合地基是否具有应力扩散的效应受很多因素影响 ,如加固层的几何性质、荷载分布的几何性质等。因此 ,应具体分析工程中遇到的实际问题 ,不能一概而论     

裂隙介质溶质运移试验研究

介绍了自行研制的裂隙介质溶质运移试验测试系统,与国内外同类试验装置相比,该测试系统可以对不同尺寸的裂隙介质进行溶质运移试验,在裂隙介质中布设了测试流体压力、温度、浓度的传感器,可以对原样裂隙中各点的溶液浓度进行直接测量,以此来获得溶质在裂隙介质中的运移规律。应用该测试系统进行了NaCl示踪剂溶液在裂隙介质中运移的试验,并用解析–优化方法求解了裂隙介质中NaCl示踪剂溶液运移的水动力弥散参数。     

地下水污染数值模拟中的样条4方法

采用三次样条函数方法中的样条４方法，对地下水污染中的水动力弥散方程进行求解，并在一维问题中与解析解进行了比较，结果表明，样条４方法在地下水污染数值模拟中，对抑制数值弥散是一种有效的好方法。     

基于半空间模型和弥散试验的场地地下水污染物自动溯源算法研究

选用的研究场地为具有地下水污染风险、布设有大量监测孔的孔隙型场地,利用弥散试验得出相关参数,进而计算出污染物运移的最大位移和最小位移。引入半空间模型,分别以污染监测孔和疑似泄露装置中心点为圆心,最大位移和最小位移为半径画圆,初步圈定污染源范围OA、OB。进一步利用等水位线作为分界线,OA范围内剔除下游部分、OB范围内剔除上游部分,运用专家经验模型和历史数据进行排除,剔除干扰项,缩小疑似污染源范围,最后将该算法发布为服务应用于地下水监测系统,达到溯源的目的。结果表明,基于半空间模型和弥散试验的场地地下水污染物自动溯源算法在目标区地下水污染源识别上具备较好的适用性,避免了现场人员溯源经验不一而产生误判。     

聚羧酸共聚物的表征及对水泥分散性研究

通过“分子设计“,研制了有不同侧链的聚羧酸共聚物,并用红外光谱对产物结构进行表征,着重讨论了聚乙二醇分子量对水泥分散性能的影响。实验结果表明:通过控制侧链长度,使聚羧酸共聚物具有最佳的分散性能。     

Numerical calculation of separated flow past a circular cylinder using panel technique

In the present investigation, a potential flow model based on panel technique, has been developed for calculation of bubble type separated flow past smooth and rough circular cylinder. Free vortex lines are assumed to emanate from the points of separation that converge downstream of the body. The converged wake shape is iteratively obtained by integrating the velocity vectors at the collocation points on the wake panels. Effect of vorticity dispersion in the wake, which plays the dominant role in the flow separation phenomena, is incorporated in the flow model. It has been observed that separated flow past circular cylinder for different Reynolds number and surface roughness can be calculated with reasonable accuracy with appropriate values of vorticity dispersion factor (λ).     

弯曲元试验高精度测试土样剪切波速方法

在HX-100型多功能三轴仪上开发了压电陶瓷弯曲元剪切波速测试系统,研究了高精度测试不同种类和刚度土样剪切波速的方法以及剪切波速弥散性问题,并将弯曲元测试结果与DrnevichLong-Tor型共振柱试验结果进行了对比。研究结果表明,对不同种类和刚度的土样,通过选用合适的激发波形和频率就可以消除接收波形的近场效应和过冲现象,高精度地确定土样剪切波速和极小应变剪切模量;在所使用的激发频率范围内,剪切波速不具弥散性。     

隆起或凹陷的非均匀介质 起伏地形中的表面波

利用曲线坐标描绘局部隆起或凹陷的典型起伏地形，讨论了在介质性质随深度变化的非均匀起伏半空间中的Ｌｏｖｅ波和Ｒａｙｌｅｉｇｈ波的传播规律。给出了决定频散关系的超越方程，并用数值方法计算出了频散曲线。