高压环境条件下注浆模型试验系统设计

注浆工程常常在高地层压力、高水压力的地质环境条件下进行(如煤矿堵水或注浆加固工程)。为了研究高压环境条件下注浆浆液的渗流扩散特征,作者研制了可形成5MPa以上高压环境的注浆试验系统。该试验系统由四个功能模块组成,并可分为四个设备子系统。该试验系统的核心设备高压注浆模型试验装置中应用压力传导管解决了高压罐体内部监测设计所遇到的尺寸效应、传感器防腐、高压密封等难题。     

盾构机下穿桩基施工对单桩承载力影响的数值研究

在大型有限差分软件FLAC3D平台上进行二次开发,利用内嵌FISH语言编程,对盾构隧道动态施工过程中上部基桩承载力的影响进行数值仿真模拟,模型考虑盾构前方土仓压力、盾尾同步注浆、注浆凝结和未凝结两种状态以及衬砌管片施加等施工参数。从桩侧摩阻力、桩端阻力等方面对盾构开挖过程中上部桩基承载力进行分析,以及土仓压力变化对承载力影响。研究结果表明：随着隧道开挖,桩侧摩阻力、桩端阻力发生复杂变化,桩底部出现负摩擦力,桩端轴力为拉力,对基桩竖向极限承载力有一定的影响;并且开挖面距桩轴线不同位置,土仓压力对基桩竖向极限承载力影响不同。     

填隙幂率流体下两刚性圆球相对错移时的粘性阻力

湿颗粒离散元模型以两球作用时填隙流体定常流动解为基础,其中切向作用是难点,国外仅有Goldman的牛顿流体渐近解.基于Reynolds润滑理论导出了两刚性球切向错动时填隙幂律流体的压力方程,并利用傅立叶级数展开简化,通过数值解法得到相应的压力分布、黏性阻力及阻力矩.该方程的解较之作者先前对速度场附加假定的结果精确,而当幂指数为1时等价于Goldman的牛顿流体渐近解.     

黄土中压力型锚索锚固段应力分析

为研究黄土地区压力型锚索锚固机理，根据压力型锚索锚固段受力状态，基于三线型剪切-滑移模型，推导了注浆体与岩土体界面在弹性阶段所对应的剪应力及轴向应力分布的闭合解．根据相关压力型锚索锚固试验数据，采用推导的闭合解计算了不同张拉荷载作用下界面的剪应力分布，并与试验结果进行了对比．结果表明，各级张拉荷载作用下注浆体/岩土体界面剪应力的分布及其最大值与试验结果基本吻合，验证了本文提出解析模型的正确性与可靠性；压力型锚索锚固界面剪应力呈指数分布规律，在承压板附近剪应力分布集中且应力较大，随着离承压板距离的增大，剪应力逐渐减小；压力型锚索锚固界面剪应力峰值随外荷载增大而增大．研究结果可为压力型锚索的设计和计算提供一种理论参考．     

注浆沉降法建筑物纠偏加固机理与关键技术研究

结合用注浆沉降法并辅以高压旋喷注浆对某小区典型不均匀沉降建筑物进行纠偏和地基加固的工程实例,着重分析了注浆沉降法纠偏加固的技术原理,并讨论该工法的控制要点;对注浆浆液配合比、注浆孔平面位置、加固深度、注浆量、注浆压力、高压旋喷注浆等设计参数的影响进行了研究探讨,提出加强纠偏加固施工动态控制的重要性。研究和工程实践表明,用注浆沉浆法并选用合适的注浆参数进行建筑物纠偏和地基加固,能使建筑物不均匀沉降得到调整的同时,复合地基承载力得到提高,具有较好的建筑物纠偏和地基加固效果。     

微扩散管内幂律流体在不同外电场驱动下非稳态流动数值仿真

电场驱动下的非牛顿流体在微米级扩散管道内非稳态电渗流动特性是MEMS管设计人员关注的焦点,大部分实际液体可近似为用幂律模型描述的纯粘性流体,所以论文针对幂律流体在有限长微扩散管道内在两种不同形式的外加电场驱动下的非稳态电渗流动情况进行数值仿真.基于Ostwald-De Wael幂律模型和连续介质假说,采用高精度紧致有限差分离散二维完全Poisson-Boltzmann电势方程和Cauchy动量方程,对恒定电场及满足Maxwell方程的电场进行数值仿真,讨论了微扩散管中幂律流体在两种不同外加电场驱动下的瞬时流场分布的差异.结果表明,初始时刻固定扩散角和无量纲壁面电势,无量纲电动宽度的变化对幂律流体电渗流速度分布影响较大;在微扩散管上游等截面处,由恒定电场驱动及Maxwell电场驱动电渗流速度分布差别极小,在扩散管中下游则出现了明显的差别;由恒定电场驱动下的电渗流动在扩散管不同截面下的速度峰值相近,但Maxwell电场诱导的电渗流速度峰值则随管道半径变化出现较大差别.对于外加电场驱动的电渗流动,不同形式的外电场可使流场产生较大差别,而不同性质的流体也会形成不同的流场分布.     

流体静压型机械密封的三维传热数学模型及端面温度分析

建立了静环倾斜时流体静压型机械密封的三维稳态传热模型,考虑流体黏度随压力、温度的变化,建立了压力、温度的控制方程,采用有限差分法,分析研究了倾斜量、结构参数及操作参数对机械密封温度分布的影响规律.结果表明,端面的最大液膜压力和最高温度随静环倾斜量的增加而增大,倾斜量越大,压黏效应越显著;端面温升受密封的结构参数、操作参数影响明显.静环端面锥角越大,温升越小;流体注入温度越低,温升越大;动环转速越高,温升越大.     

膨胀性非牛顿流体多孔介质流动的模拟分析

在表征体元尺度采用格子Boltzmann方法分析膨胀性非牛顿流体在多孔介质中的流动,基于二阶矩模型在演化方程中引入表征介质阻力的作用力项,求解描述渗流模型的广义Navier-Stokes方程．采用局部法计算形变速率张量,通过循环迭代得到非牛顿粘度和松弛时间．对多孔介质的Poiseuille流动进行分析,通过比较发现结果与孔隙尺度的解析解十分吻合,并且收敛较快,表明方法合理有效．分析了渗透率和幂律指数对速度和压力降的影响,研究结果表明,膨胀性流体的多孔介质流动不符合达西规律,压力降的增加幅度小于渗透率的减小幅度．当无量纲渗透率Da小于10-5时,流道中的速度呈现均匀分布,并且速度分布随着幂律指数的减小趋于平滑．压力降随着幂律指数的增加而增加,Da越大幂律指数对压力降的影响越明显．     

幂律流体圆柱绕流的格子波尔兹曼模拟

基于插值补充格子波尔兹曼方法和幂律流体的本构方程,建立了贴体坐标系下适用于幂律流体的格子波尔兹曼模型,模拟了幂律流体的圆柱绕流问题,采用非平衡外推格式处理圆柱表面的速度无滑移边界,利用应力积分法确定曳力系数和升力系数,并与基于标准的格子波尔兹曼方法和有限容积法获得的数值数据进行对比,吻合良好. 进行了网格无关性验证之后,分析了稳态流动时,不同雷诺数下幂律指数对于尾迹长度、分离角、圆柱表面黏度分布、表面压力系数及曳力系数的影响,以及非定常流动中,幂律指数对于流场、曳力系数、升力系数和斯特劳哈尔数的影响. 获得的变化规律与基于其他数值模拟方法得到的结果相一致,充分验证了模型的有效性和正确性. 结果表明:插值补充格子波尔兹曼方法可以用来模拟幂律流体在具有复杂边界流场内的流动问题,通过引入不同的非牛顿流体本构方程,该方法还可以进一步应用于其他类型的非牛顿流体研究中.      

梯度弹性基础上正交异性薄板的弯曲

基于能量法和变分原理,采用双参数弹性基础模型,研究了梯度弹性基础上正交异性薄板在分布载荷作用下的弯曲问题。首先,根据能量法与变分原理,给出了梯度弹性基础上正交异性薄板的弯曲微分平衡方程,并得到了梯度弹性基础刚度系数 与 的计算表达式;进而,假设 向正应力在厚度方向上均匀分布,推导了弹性基础 向位移衰减函数 的计算式。在算例中,通过将梯度弹性基础退化为均质基础,并与Vlazov模型对比,证明了本文理论的正确性;最后,求解了弹性模量呈幂律分布的梯度基础上薄板的挠度分布,分析了基础上下表层材料弹性模量比 与体积分数指数 对薄板挠度分布的影响。     

Filtration Behaviour of Cement-Based Grout in Porous Media

Filtration behaviour of cement particles, especially under the high grouting pressure with a rapid grout flow velocity, has a significant effect on the grout injection. However, there have been few studies on this field where the governing equation of this behaviour remains unclear. In the present study, a novel experimental procedure for grout injection was adopted to acquire the spatial and temporal variations in porosity and viscosity of high-speed grout flow in coarse sand. Experimental observations showed that there were dramatic variations in viscosity and porosity during the grout penetration within the first 50 s, suggesting that the high velocity had a significant influence on the distribution of the filtration coefficient. A model based on the Stokes–Brinkman (S–B) equation and advection–filtration equations was established to describe the filtration of grout flow in porous media. Meanwhile, numerical solutions from both the proposed model and traditional Darcy’s law were compared with experimental results. The comparative results showed that the proposed approach can match the laboratory tests well; the analysis indicated that Darcy’s law was unable to properly describe high-speed grout flow in porous media due to the lack of a shear force and the inertial term. Nonuniform filtration behaviour of cement grout flowing in porous media was revealed. Due to the nonuniform distribution of the pore velocity isoline caused by Poiseuille flow, it led to a heterogenous distribution of porosity as well. Parametric studies on the applicability of Darcy’s law and S–B equation for grout flow were discussed, in which an error of less than 10% was calculated when the Reynolds number was less than 2.5.     

固井工程中的流动问题

固井是油气井在建过程中的重要工程,一般分下套管和注水泥两个过程．本文结合作者近年来的研究,着重阐述了钻井液、前置液、水泥浆在环形空间中流动的流体力学问题,包括：高温高压下的水泥浆流变性、偏心环形空间中浆液的流动特性、钻井液-前置液和前置液-水泥浆界面的稳定性等,介绍了国内外学者对这些问题的研究进展,提出了今后应深入研究的问题．     

Analytical solutions of the helical flow of non newtonian fluid in eccentric annular space

ＡＮＡＬＹＴＩＣＡＬＳＯＬＵＴＩＯＮＳＯＦＴＨＥＨＥＬＩＣＡＬＦＬＯＷＯＦＮＯＮＮＥＷＴＯＮＩＡＮＦＬＵＩＤＩＮＥＣＣＥＮＴＲＩＣＡＮＮＵＬＡＲＳＰＡＣＥＺｈａｎｇＨａｉ－ｑｉａｏ（张海桥）ＷｕＪｉ－ｚｈｏｕ（吴继周）（ＴｈｅＤｅｐａｒｔｍｅｎｔｏｆ...     

古全风化花岗岩的灌浆作用机理研究

通过现场灌浆试验及对灌浆前后古全风化花岗岩的物理力学性质指标测试，结合灌浆作用过程的有限元分析，表明受过上覆岩体自重压力作用后的古全风化岩由于岩体结构发生恢复或再生，物理性质明显优于现代全风化岩；而受一定围压作用的古全风化花岗岩，在一定灌浆压力下，一是使灌浆液较难进入岩石微小孔隙中，再则随灌浆压力逐渐加大，又使相对均质的岩体派生新的拉张裂隙，且将大量浆液吸收。由于上述作用，表现出古全风化花岗岩由灌浆前的结构面不发育，具均质结构变成灌浆后的裂隙（即水泥结石条带）较发育，具非均质结构的特征，且灌浆后岩体的物理力学性质指标有所增长，但提高幅度较小。     

Performance modeling and analysis of blood flow in elastic arteries

Nomenclature　　τ　　wallshearstressγshearrateτy yieldstressηc Cassonviscosityktheconsistencyindexnnon_Newtonianindexτp shearstressofthepthelementωangularvelocityRvessel’sradiusCwavespeedM　　magneticparameter (Hartmannnumber)u,w　velocitycomponentinther_andz_directions,respectivelyP　　pressureα　　unsteadinessparameter k , R meanparametersTp relaxationtimeofthepthelementρ densityIntroductionTheimportancetoatherogenesisofarterialflowphenomenasuchasflowseparation ,recirculationands…     

The effects of filtration on the injection of cement-based grouts in sand columns

This article presents injection experiments and modeling of cement based grout in sand. In particular, it focuses on the role of filtration during the sand impregnation by the grout. One-dimensional injection tests in sand columns are performed. In these, the mass intake of the sample and the injection pressure are measured to quantify the effects of filtration during grouting. The cement-to-water ratio of the grout and the initial density of the soil are also studied. The modeling of these tests is achieved by incorporating the filtration and the damage coefficients in the classical transport in porous media equations. A method is proposed to determine these coefficients. The method simultaneously relies on both analytical analysis and experimental measurements. Density and viscosity effects are also considered in the model equations which are solved using the finite element method. The simulation of an injection test proves that the model is suitable to recover the injection pressure obtained experimentally. Finally, both experimental and numerical results reveal the importance of including filtration when analyzing one-dimensional injections of cement based grouts in sand.     

深孔预裂爆破注浆封孔材料力学特性实验

针对深孔预裂爆破注浆封孔材料配比选择问题,以水泥、速凝剂、水为注浆原料,开展不同材料配比、不同养护时间的单轴抗压强度实验,分析封孔长度与材料力学特性的关系。结果表明:不同配比深孔预裂爆破注浆材料的抗压强度范围为0.60~4.49MPa,最大弹性模量为0.527GPa;注浆材料的抗压强度和弹性模量与水灰比呈负相关关系,与速凝剂和水泥的比例(A/C)呈正相关关系;同一配比条件下,注浆材料抗压强度随养护时间增加而增大,6h后趋于平稳。计算得出封孔长度与材料抗压强度、侧压系数呈负相关关系。综合实验及分析得出,深孔预裂爆破施工中可选用水泥、速凝剂、水为1∶1∶1的比例配比封孔,封孔后养护6h放炮。     

Experimental and numerical investigations of pressure drop in a rectangular duct with modified power law fluids

Numerical solutions are presented for fully developed laminar flow for a modified power law fluid (MPL) in a rectangular duct. The solutions are applicable to pseudoplastic fluids over a wide shear rate range from Newtonian behavior at low shear rates, through a transition region, to power law behavior at higher shear rates. The analysis identified a dimensionless shear rate parameter which, for a given set of operating conditions, specifies where in the shear rate range a particular system is operating, i.e. in the Newtonian, transition, or power law regions. The numerical results of the friction factor times Reynolds number for the Newtonian and power law region are compared with previously published results showing agreement within 0.05% in the Newtonian region, and 0.9% and 5.1% in the power law region. Rheological flow curves were measured for three CMC-7H4 solutions and were found to be well represented by the MPL constitutive equation. The friction factor times Reynolds number values were measured in the transition region for which previous measurements were unavailable. Good agreement was found between experiment and calculation thus confirming the validity of the analysis.     

New model for single spherical particle settling velocity in power law (visco-inelastic) fluids

Particle settling in a non-Newtonian power law fluid is of interest to many industrial applications, including chemical, food, pharmaceutical, and petroleum industry. Conventionally, the Newtonian model for the drag coefficient prediction is extended to non-Newtonian fluids. The approach of merely replacing a viscosity term in Newtonian correlation with a power law apparent viscosity is reported to be inadequate.