基于数值模拟的地铁工程降水效果分析——以乌鲁木齐市轨道交通2号线工程为例

随着城市的建设及交通的高速发展,出现了大量的基坑工程,存在着基坑降水问题亟需解决。文章分析了乌鲁木齐轨道交通2号线其中一路段的水文地质和工程地质条件,根据计算提出了降水方案,并采用数值法对降水方案进行预测,认为该方案具有可行性,可作为地铁2号线设计与施工的水文地质方面依据。     

微山湖二线船闸基坑涌水量计算

以微山湖二线船闸基坑降水计算为例,把地表水发育地区、含水层和隔水层互层交错的水文地质条件,近似为无限均质含水层。基坑降水时基坑降水与均质含水层、设定降深、长期稳定开采时地下水资源计算雷同,理想大井法适用于基坑涌水量估算。     

基于双欧拉模型的流化床气固两相流场数值模拟

为解决低流化风速下采用Syamlal-O' Brien曳力模型计算流化床内流化过程误差较大的问题,选择曳力模型预测初始最小流化条件,结合实验数据,修正Syamlal-O' Brien曳力模型,并采用双欧拉模型对均匀床内低速气固两相流场进行数值计算.结果表明:修正Syamlal-O' Brien曳力模型计算结果略小于实验...     

多普勒雷达资料在飞机增雨作业中的应用研究

利用滨州714SDN雷达体积扫描资料、济南探空和机载PMS微物理探测资料,按降水冷云云层分布特点,选择不同Z-M关系计算降水条件下各特定层垂直积分含水量;结合天气资料及雷达速度场分布特征,分析降水云层演变特征及人工增雨播云条件,确定增雨作业时间和区域.     

一个双层渗流系统耦合结构地下水资源评价实例

本文提供了一个用有限差分法求解孔隙潜水一裂隙岩溶承压水双层渗流系统耦合结构的数学模型进行地下水资源评价的实例。其特点是:1.将参数调整和水量均衡论证有机地结合在一起,保证了计算结果的可靠性;2. 采用了分段调参的新方法,提高了精度,充分利用了水位实测资料;3. 进行了初始水位拟合,提高了水位拟合速度;4. 设计了三种开采方案,进行了十年水位预测。     

油藏渗流—应力耦合计算区域分析

在实际油藏开采过程中,储层区域发生地下流体渗流,岩土力学平衡的影响范围大于渗流的计算区域,并影响储层的上覆盖层和下部地层。在流固耦合油藏数值模拟中,地下流体渗流和岩土力学的计算通常采用相同的计算区域,并限定在储层范围内,未考虑完整的应力计算区域,造成计算结果存在偏差。采用改进的有限元—有限体积混合方法,对地下流体的渗流和岩土的力学平衡分别采用不同的计算区域和不同的网格密度进行计算,分析渗流—应力耦合数值计算中计算区域的选取对计算结果的影响。规则储层与背斜圈闭储层算例数值模拟结果表明:应力计算区域的选取影响计算结果,计算结果偏差与非储层区域材料的参数相关,其中拱效应是计算结果出现偏差的主要原因。该结果为流固耦合油藏数值模拟提供指导。     

水平井钻柱摩阻扭矩分段计算模型

根据水平井接触和受力特点,利用分段计算方法,建立水平井钻柱摩阻扭矩计算模型;采用三维纵横弯曲梁理论,计算钻柱BHA(底部钻具组合)段摩阻扭矩;采用软杆模型,求解BHA以上钻柱段的摩阻扭矩;对井眼曲率变化较大及刚度较大的加重钻杆井段软杆模型加以修正,考虑钻柱屈曲的影响,建立适合水平井的摩阻扭矩三维分段计算模型.应用结果表...     

渗透作用下滑带细观结构演变特性

库岸滑坡受到库水升降作用影响, 内部渗透压力会产生周期性的变化。动态渗透压力会导致滑带结构与强度产生劣化, 进而影响滑坡整体稳定性。为揭示滑带在渗透作用下的结构演变特征, 通过室内渗流试验结合CT扫描技术获取了黄土坡滑坡滑带在不同渗流条件下的细观结构特征, 采用Avizo软件量化滑带细观结构参数, 定量分析了不同渗透条件下滑带结构的演变规律。结果表明, 滑带的渗透系数随渗流时长的增加而呈指数形式下降, 且水力梯度越大最终试样的渗透系数越小; 连续的CT重构图像显示渗流过程中部分黏土团聚体发生解体, 大孔隙被附近的细颗粒逐渐充填, 试样结构的宏观均一性增强; 统计数据表明滑带土的表观孔隙率由5%下降到了1%, 等效直径小于80 μm的孔隙占比随渗流时长的增加而增多, 而等效直径大于80 μm的孔隙占比随渗流时长的增加而减少。结果证明周期性渗透作用会影响滑带内孔隙结构的分布特征, 细观上表现为大孔隙被小颗粒充填, 导致渗流通道变得细长而弯曲, 孔隙的有效连通性被削弱, 宏观上表现为渗透系数随渗流时长的增加而降低。      

毛乌素湖盆滩地湖水与地下水交互作用分析

湖水与地下水交互作用对于水资源合理开发与利用有着重要意义。基于温度示踪的原理，采用解析法、数值法2种方法，分析了湖床底部埋深0~0.4 m湖水与浅层地下水交互关系，并与水动力学方法进行了对比。结果表明，2018年5月20日至28日，湖水与地下水之间的垂向渗流速度为2×10-7~1×10-6 m/s，且在埋深0.4 m时大于埋深0.2 m处。降水会对解析法的结果造成一定影响，0.4 m处受到降雨影响表现为一定的滞后性。无降雨干扰情况下，数值法与水动力学方法估算结果较为吻合，且3种方法的计算结果处于同一数量级。同时，湖床沉积物体积热容和孔隙度2种参数对计算结果影响较大。在半干旱地区湖水与地下水交互研究中，数据较完备时，数值模拟法是更好的选择。      

深厚软土中超大型"悬浮"基坑水泥土重力式挡土墙位移控制措施

本文就珠海某基坑水泥土重力式挡土墙的位移及其控制进行分析探讨,论述了应用轻型钢管支撑对基坑位移控制的可行性,并详细阐述了其计算方法及施工工艺.     

济南西客站综合客运枢纽工程抽水试验探讨

济南西客站综合客运枢纽工程场地基坑拟开挖深度范围内有2层较好的含水层,地下水具有一定的承压性,2层水之间局部地段是沟通的,水力联系较密切。对2含水层进行了分别及综合抽水试验,取得了详实的水文地质参数,为基坑降水提供了较为可靠的设计参数。     

Local scour and the laws of scour pit’s shape downstream of debris flow sabo dam

The erosion shape and the law of development of debris flow sabo dam downstream is a weak part in the study on debris flow erosion. The shape and development of scour pit have an important effect on the stability and safety of debris flow sabo dam, which determines the foundational depth of the dam and the design of protective measures downstream. Study on the scouring law of sabo dam downstream can evaluate the erosion range and reasonably arrange auxiliary protective engineering. Therefore, a series of flume experiments are carried out including different debris flow characteristics （density is varying from 1.5 t/m3 to 2.1 t/m~） and different gully longitudinal slopes. The result shows that the scour pit appears as an oval shape in a plane and deep in the middle while superficial at the ends in the longitudinal section, the position of the maximum depth point moves towards downstream with an increase of flume slope angle. The maximum depth of scour pit is mainly affected by the longitudinal slope of gully, density of debris flow, and the characteristics of gully composition （particle size and the viscosity of soil）. The result also indicates that the viscosity of soil will weaken the erosion extent. The interior slopes of scour pit are different between the upstream and the downstream, and the downstream slope is smaller than the upper one. For the viscous and non-viscous sands with the same distribution of gradation, the interior slope of non- viscous sand is smaller than the viscous sand.According to tbe regression analysis on the experimental data, the quantitative relationship between the interior slope of scour pit, slope of repose under water and the longitudinal slope of gully is established and it can be used to calculate the interior slope of scour pit. The results can provide the basis for the parameter design of the debris flow control engineering foundation.     

EEMD-PSOGSVM耦合模型在深基坑位移预测中的应用

针对单一预测模型的不足,提出EEMD分解与粒子群灰色支持向量机（particle swarm optimization grey support vector machine,PSOGSVM）相结合的基坑位移预测模型。以基坑时间序列的混沌性为基础,利用EEMD分解时间序列,采用相空间重构技术构造样本,应用PSOGSVM模型进行基坑预测,并与GM(1,1)、SVM、遗传小波神经网络进行对比。结果表明,该算法预测精度好,具有良好的稳定性,可有效地应用于基坑位移预测。     

Experimental study on simulation test instrument and its penetration performance of soil infiltration clogging

The three-dimensional seepage simulation test device for siltation dam foundation soil is a multifunctional penetration instrument which is designed for the simulation of infiltration clogging,seepage damage,and dam seepage and so on. This device is different from the traditional instruments for the rock and soil permeability. In order to verify the practicability of the device,the authors collected the soil samples for laboratory penetration test,observed the seepage damage phenomenon,and obtained the dynamic change curve of permeability coefficient and isopotential map of water pressure. At the same time,the Geostudio finite element software is used to simulate the steady seepage of the test device. By contrast of the isopotential maps between simulation and actual water pressures,it is found that they are approximately the same. It is proved that the test data of the device is scientific and reliable,reaching the results of the test and design purposes. The instrument can be used in many aspects of experimental study on soil seepage.     

Elastic-plastic analysis for pile-anchor supporting system of deep foundation pit

By using numerical analysis methods to simulate the deep excavation, a lot of analyses are established on the basis of two-dimensional plane strain, ignoring the fact that foundation pit possesses three dimensions. For soil constitutive relation, people always take linear and nonlinear model, without considering the plastic behavior of soil. Using plastic-elastic hardening model to simulate constitutive relation of soil characteristics, the authors carried out mechanical analysis for pit excavation and support. The results show that the analysis for the stress state of pile anchor system is an effective way which provides theoretical basis for calculation of soil displacement.     

基坑围护设计与实测分析比较

通过不同围护软件分析计算并与实测结果进行比较 ,指出土层水平抗力系数“m”取值的关键性 ,基坑开挖是一个动态而复杂的过程 ,理论计算会有一定的差距     

边界元法在地下水补给量计算中的应用

本文是边界元法在地下水补给量计算中应用的一次尝试,它成功地把边界元法应用到考虑有垂向补给或排泄的实际水文地质问题中。文中详细地推导了考虑有垂向补给或排泄均质各向同性承压含水层非稳定流边界元法的计算公式,结合长春市八里堡群井开采试验的水位观测资料计算了河流边界的补给量;分析了目前边界元法在水文地质计算中出现的时间积分和面积积分问题,在这两个问题的解决上做了些改进;结合简单水文地质模型给出了边界元法的精确度。     

Analysis and evaluation on seepage stability of Hongxing reservoir dam , Heilongjiang

Hongxing reservoir was constructed on the floodplain of Hulan River in Heilongjiang. The geological problem of the reservoir is the seepage of the dam base and its related seepage stability. The leakage of the reservoir is caused by the water head differences between the upstream and downstream of the dam. Severe seepage could decrease the engineering benefits of the reservoir. Moreover, infiltration function of water will influence the safety of the dam. Through the analysis on the granule constitute and the formation of the dam base, the types of the seepage failure apt to happen were defined and the anti-infiltration and the permissible depression ratio were determined. Using the numerical simulation software GMS, the two-dimension numerical modeling has been carried out to analyze the seepage field of the reservoir. Through the two conditions modeling with concrete impervious wall and no concrete impervious wall, the largest flow rate, single-wide seepage discharge and the max infiltration gradient of the dam base were calculated. According to the permeable depression ratio of the dam base, the seepage stability of Hongxing reservoir dam base was analyzed.     

深基坑双层土体空间效应分析

随着城市的不断发展,基坑开始由传统的二维模式向三维空间转变。该文借助于坑壁土体的三维破坏模式,推导出双层土体的破坏模型,在此模型基础上基于土体塑性上限理论及极限平衡分析理论,提出了考虑空间效应的土压力计算公式以及相应的空间效应影响系数。该计算公式可用于基坑土钉墙、护坡桩、地下连续墙等支护系统的设计。     

Research on infiltration clogging effect and its application prospect in anti-seepage project

Clogging effect, as a new concept in geological engineering, is a phenomenon of permeability decreasing under seeping in reservoir dam foundation of the alluvial and diluvial deposits with deep and thick layer, coarse particle and high permeability in mountains-gully rivers of Tibetan Plateau. A clogging infiltration instrument has been designed successfully and a series of simulation tests have been done. Based on large amounts of data, it is confirmed that the existence of the clogging effect and the law of infiltration clogging is found out. Three indexes are proposed such as "optimal size of particle", "optimal size range of particle" and "characteristic pore", which are closely related with effect of infiltration clogging. The concept and results can offer a new idea to solve problems on anti-seepage of dam foundation in mountains-gully rivers environment and to study artificial clogging, meanwhile supplement of the concept of seepage deformation.