高温岩体地热开发的块裂介质固流热耦合三维数值模拟

在深入论述高温岩体地热开发研究与发展现状的基础上，提出了高温岩体地热开发的块裂介质固流热耦合数学模型及其数值模拟方法，提出了该数学模型详细的求解策略与求解方法，对6000m深的高温岩体地热开发进行了详细的数值分析，揭示了：（1）岩体温度随地热提取降低及其分布变化的规律；（2）岩体中基质岩块内、裂缝内应力随地热提取的降低规律；（3）裂缝宽度随地热提取变化的规律，对高温岩体地热开发决策、技术方案选择提供了理论基础及其方法。     

预紧力锚杆支护的3D-FSM·DDM数值模拟系统研究与开发

在已经开发的3D-FSM·DDM间接边界元数值模拟系统的基础上,进行含预紧力端锚固锚杆支护功能的数值模拟系统研究与开发。算法的基本思想是:根据岩体与锚杆重合部分两端点的位移差与锚杆相应部分两端点的轴向位移差相等,补充方程数量,并与其他单元在边界条件下联立求解全部虚拟应力未知量;求取后利用其进一步求解围岩任意点的应力、位移及稳定性。所开发的数值系统与FLAC3D数值模拟系统进行了比较,验证本边界元系统的可靠性。开发后的边界元数值模拟系统可广泛应用于矿山、隧道等大型岩土工程的围岩稳定性分析。     

流固耦合模型用于陷落柱突水的数值模拟研究

采动岩体动力学失稳与渗流突变是发生矿井突水的直接原因.以岩体的损伤演化为主线,考虑岩体的非均质性、渗流与变形的耦合效应,提出流固耦合条件下岩石破坏过程的本构关系,并在COMSOL Multiphysics的编程环境下通过MATLAB编程开发了突水模拟及突水危险性评价的软件系统.结合范各庄矿陷落柱突水的实际,用该数值模拟系统开展陷落柱突水的数值模拟.数值模拟再现了突水发生的整个过程,据此对陷落柱突水危险性进行了评价分析,并探讨了突水发生的机理.     

高温岩体地热资源模拟与预测方法

研究了基于三维稳态热传导理论并忽略对流换热及地质构造等次要因素影响的地温场与地温梯度场的反演方法。该方法可以在大尺度上数值模拟岩体中地温的空间分布状况,并预测高温岩体地热资源量。以云南省腾冲热海热田为例,模拟和分析了地质体的地温与地温分布梯度场的特点及其形成原因,并对热田高温岩体地热资源量进行了预测评价。提出的高温岩体地热资源模拟与预测方法具有重要的理论价值,研究结果可为热海热田地热资源的开发和利用提供参考。     

随机介质固热耦合模型与高温岩体地热开发人工储留层二次破裂数值模拟

在高温岩体地热开发中,针对岩石矿物组分及其分布的不同,将热膨胀系数作为随机介质,在平面应变模型下,建立了随机介质的温度场和应力场耦合数学模型,并推导了该耦合问题的有限元格式。在正态分布、韦伯分布 2 种随机分布下,进行了高温岩体地热开发数值模拟试验,揭示了岩体温度场和应力场的特征及变化规律。研究表明,热膨胀系数的概率分布形式对岩体热破裂规律有重要影响。     

岩体大规模自然崩落模拟系统的初探

首先简单介绍了FLAC模拟系统,基于岩体强度准则判据失效下的岩体,运用模块化思想,构建了岩体大规模自然崩落模拟系统总体框架,并经过模拟系统实例分析,得出了岩体大规模自然崩落模拟系统的优点及其功能。     

交通安全驾驶模拟系统中的人机界面设计

驾驶模拟系统可以通过模拟现实交通环境实现研究驾驶行为、提高车辆及交通安全性的目的.以Quest3D为主要平台,基于蓝虎驾驶模拟器,设计开发了驾驶模拟系统的视觉模拟子系统、声音模拟子系统、体感模拟子系统、操控执行子系统等人机界面模块,分析了关键技术的设计和实现,能较快速、真实地模拟道路场景等现实驾驶环境.通过本模拟系统可以有针对性地研究驾驶行为对交通安全的影响,是进行交通安全性研究的有效途径.     

高温岩体地热钻井施工关键技术研究

 高温岩体地热开发中首先需要解决的问题是深钻施工。根据中国高温岩体地热资源赋存的地质特征,在试验研究、理论分析和数值模拟的基础上,提出高温岩体地热钻井施工中三大关键技术问题：钻井围岩稳定性控制技术、高温高压破岩技术、高温高压钻井液技术。进而从高温岩体地热开采中钻井围岩失稳的主要因素、热力耦合作用下钻井围岩流变特性、高温高压下钻井围岩变形破坏规律与失稳临界条件,提出高温岩体地热深钻施工中钻井围岩稳定性控制技术。通过对高温高压下花岗岩中冲击破岩、切削破岩、冲击–切削复合破岩的试验研究及不同温度下3种破岩方式的比较,获得高温高压下3种破岩方式的破岩规律。最后从高温对钻井液的影响、地热钻井对高温处理剂的一般要求、钻井液的性能对井壁稳定的影响及应对措施,提出解决高温岩体地热深钻施工的钻井液技术要求。高温高压下深钻施工关键技术的研究,对于人类探索地球、开发地球深部的能源与资源具有重要的科学与工程意义。     

雄胜高温岩体地热开发的数值计算进展

主要介绍日本电力中央研究所为秋田县雄胜高温岩体地热开发试验项目——近年开发的热-水流动藕合数值计算源程序GEOTH3D的原理、特点、应用现状和尚待改善的一些问题，并结合国际上其他相关软件的进展情况，对下一步可能的工作倾向进行了探讨。     

岩石破裂过程分析(RFPA2D)系统的细观单元本构关系及验证

从岩石的细观非均匀性特点出发，应用弹性损伤力学，对岩石破裂过程分析数值（RFPA^2D)模拟系统的本构关系进行了描述。用RFPA^2D系统模拟了岩石试样在单轴或双轴载荷作用下的强度特征和破坏形态，通过与实验结果对比验证了该本构关系和数值模拟系统的合理性和有效性。     

Soil-pile interaction in inhomogeneous transversely isotropic media

Through a rigorous mathematical formulation, this paper considers the axisymmetric interaction analysis of a thin-walled cylindrical pile with finite length embedded in an exponentially graded transversely isotropic half-space under axial loads at the top of pile. The action of pile to the embedding medium is represented with axial and radial ring loads and the relevant set of Green's functions for the pile and semi-infinite soil medium has been developed. By satisfying the compatibility conditions between the two interacting media, the interaction analysis is shown to be reducible to a pair of Fredholm integral equations. Due to the complex nature of mathematical formulations and the intrinsic singularity of stress transfer, the analytical solution of obtained boundary integral equations is not possible and a suitable numerical scheme has been developed. By means of adaptive gradient shape functions which are capable of smoothly capturing regular and singular solutions, the given Fredholm integral equations are discretized in the common boundary of interacting media and solved numerically for the interfacial stress components. The numerical procedure is verified through comparisons with previous studies and the effect of inhomogeneity of soil layer on different responses of the interaction process is discussed by presenting several numerical results.     

Shao-Zhu-Su岩石流变模型的快速显式积分算法及比较研究

 基于对Shao-Zhu-Su岩石力学流变模型及其数值算法的分析,发现传统积分算法在处理流变卷积方程时存在变量存储量大和计算效率低的缺点。运用数学变换和Taylor展开提出2种显式积分算法,即非线性显式积分算法(NEIA)和线性显式积分算法(LEIA)。通过蠕变和松弛数值试验对新算法进行验证和比较。提出的显式积分算法变量存储量较少,且避免与加载历史有关的累积求和运算,从而明显提高计算效率,使得此类内时流变模型更适合于大型岩体结构分析。需要指出的是,建议的数值积分方法也可用于其他积分型流变模型的数值处理。     

基于Floquet变换方法的单排桩隔振数值模型

基于Floquet变换方法,建立了周期性排桩隔振问题的数值计算模型。首先利用Muki的虚拟桩方法,将桩土体系分解为拓展半空间弹性土和一系列虚拟桩。利用半空间土体的基本解,自由波场解及桩土协调条件,建立了排桩的第二类Fredholm积分方程。根据Floquet变换方法,得出了排桩在波数域内的积分方程。求解该积分方程即得排桩在波数域内的解,对波数域内的解进行Floquet逆变换,即得排桩在空间域内的解。数值结果表明,Flo-quet变换方法的结果与直接叠加法的结果完全吻合。利用所建立的数值模型,文中对桩长、桩土弹性模量比、桩间距对排桩隔振效果的影响进行了分析。     

Evaluation of multivariate normal integrals for general systems by sequential compounding

System reliability analysis often requires efficient and accurate evaluation of a multivariate normal integral. Despite recent advances in system reliability analysis methods, it is still a challenging task especially when the definition of the system event is complex; the system has a large number of components; and/or the component events have significant statistical dependence. This paper presents a new method developed for evaluating multivariate normal integrals defined for general system events including series, parallel, cut-set and link-set systems. The method compounds two components coupled by union or intersection sequentially until the system becomes a single compound event. Efficient numerical procedures are developed for obtaining the reliability index of the new compound event, and the correlation coefficients between the compound event and the remaining component events, at each step of the sequential compounding. The accuracy and efficiency of the proposed method, and its applicability to various types and sizes of multivariate normal integrals are demonstrated by numerical examples.     

随机振动荷载作用下结构动力可靠性设计方法研究

以轨道结构为例建立了车辆-轨道垂向耦合动力计算模型,并使用Wilson-q数值积分方法得到了轨道结构在列车荷载作用下的随机振动响应。基于随机过程跨越理论,得到了不同跨越假设以及极值分布条件下钢轨动力响应可靠度,并与数值模拟法结果进行比较,表明对于低跨越界限,极值I型分布法的计算结果最接近精确值;对于高界限则高斯分布法效果最好。     

数值流形方法的网格自动剖分技术及其数值方法

数值流形方法包含数学覆盖与物理覆盖双重网格，数学网格用以构造流形单元的插值函数，物理覆盖确定了流形单元的积分区域。数值流形方法的前处理一直是一个难题。讨论了数值流形方法的网格自动生成技术，解决了数值流形方法的前处理问题。无论是连续性材料还是非连续性材料，数学覆盖都保持不变，因此，借助现有的有限元技术生成数值流形方法的数学网格，利用面向对象的编程方法生成了数值流形方法的物理网格。实例应用表明，这种方法是可行的和有效的。     

Effects of overlay designs on reliability of flexible pavements

Management of flexible pavements requires timely application of preventive maintenance and rehabilitation actions such as overlays. These actions are an integral part of a design strategy that minimises the use of recourses over the pavement's life-cycle. The objective of this paper is to develop a reliability model for flexible pavements that accounts for the effects of overlay designs. In this paper, the pavement responses are determined by the linear theory of elasticity for the system of pavement layers, while the pavement reliability is represented as a series system of two failure criteria: fatigue cracking and rutting. To illustrate the developed model, a numerical study is presented. Sensitivity and importance measures are computed for the parameters and the random variables included in the limit state functions. The sensitivity measures suggest that the initial asphalt layer thickness and the sub-grade stiffness are the critical predictors of the pavement performance after application of a structural overlay.     

Multinormal integrals by importance sampling for series system reliability

A structural system with multi-failure modes can be modeled as a series system if it fails whenever any of the failure mode occurs. Applying FORM, failure probability of a series system can be expressed using a complementary standard multinormal integral. However, the integral is increasingly more difficult as the dimension increases. Importance sampling method can be used to deal with such multi-fold integration. Considering the fact that the optimal importance sampling function can be determined for a linear limit state function in a uncorrelated standard normal space, this paper proposes an importance sampling function for multinormal integral as a linear combination of such optimal sampling functions. The accuracy and applicability of the method are investigated using numerical examples.     

列车荷载作用下钢轨动力可靠度分析的拟静力方法

利用模态分析法,建立了车辆-轨道垂向耦合动力计算模型。在模型中,车辆为附有二系弹簧的整车模型,钢轨被离散为双层弹性基础上的欧拉梁。采用Wilson-θ数值积分方法,得到了钢轨在列车荷载作用下的随机振动响应。基于结构动力可靠度理论的拟静力分析方法,得到了列车荷载作用下武汉轻轨系统轨道结构的可靠指标。根据计算结果,建议我国既有无缝线路轨道交通的可靠指标为3.70。     

Temperature prediction for contour-insulated concrete-filled CHS subjected to fire using large time Green’s function solutions

An accurate numerical approach is developed in this paper for thermal analysis of contour-insulated concrete-filled circular hollow sections subjected to fire, based on analytical solutions of transient diffusion equations in radial coordinate system obtained using the Green’s function approach. The steel layer is conveniently treated as a thin film with lumped heat capacitance, i.e. the temperature distribution inside the steel section is assumed to be uniform. Perfect contact conditions are assumed at both of the insulation-steel and the steel-concrete interfaces. Solutions of the heat equations are represented by large time series expansions obtained from homogeneous boundary conditions using the eigenfunction approach. The time-varying boundary conditions, i.e. the fire conditions are incorporated in terms of Stieltjes integral by means of Duhamel’s theorem. Numerical models are developed using temporal discretization, while no spatial discretization is required since spatial variables are analytically tractable. The proposed numerical scheme is not restricted to any specific fire conditions, and can be used in conjunction with parametric fire as proposed in the Eurocode.