Boussinesq-type modelling using an unstructured finite element technique

A model for solving the two-dimensional enhanced Boussinesq equations is presented. The model equations are discretised in space using an unstructured finite element technique. The standard Galerkin method with mixed interpolation is applied. The time discretisation is performed using an explicit three-step Taylor–Galerkin method. The model is extended to the surf and swash zone by inclusion of wave breaking and a moving boundary at the shoreline. Breaking is treated by an existing surface roller model, but a new procedure for the detection of the roller thickness is devised. The model is verified using four test cases and the results are compared with experimental data and results from an existing finite difference Boussinesq model.     

全站仪交汇法在高速公路路面沉降监测中的应用

文章介绍了全站仪交会法沉降监测,方便简洁地解决了测量人员不能进入的高速公路等特殊位置的测量问题,并通过对该方法的精度分析,论证了其可行性和有效性,对以后类似的测量工作提供经验和依据。     

电容测试法判断测井电缆系统故障

测井电缆因长途颠簸、拉伸及绞车缠绕挤压,电缆连接器、电缆、绞车滑环、滑环连线等部位极易出现故障。电容测试法是一种简易、快速的检测方法,该法可在现场准确诊断出故障电缆的位置。以四芯铠装电缆为例,每根缆芯的正常阻值约为80Ω/1 000m,两缆芯间的分布电容约为170PPF/1 000m。在实际检测中,根据电容较小时测点的位置,可以有效判断故障部位;而电缆故障位置则可利用电阻及电容的线性关系进行计算予以确定。     

测井仪器的故障分析与排除思路

TYSC-3Q与PSJ-2型数字测井仪是目前煤田测井中常用的二种测井仪器,在使用过程中难免发生诸如测井控制故障、声速探管故障、密度三侧向探管故障、井温、井液电阻率探管故障、电法面板故障、数字测井面板故障、电测井故障等常见故障类型。通过对各类故障因素进行剖析,指出了故障易发生的部位,并详细的介绍了检查的方法及故障的排除步骤。     

About the specification of erosion flux for soft stratified cohesive sediments

The present paper deals with the specification of bed erosion flux that accounts for the effects of sediment-induced stratification in the water column. Owing to difficulties in measuring the bed shear stress _b and the erosive shear strength _s, we suggest a series of methods that combine laboratory and numerical experiments. A simplified turbulent transport model that includes these effects helps to quantify _b and _s. Focusing on soft stratified beds, the present study considers erosion rate formulas of the form =_f exp {[T_b-T_s]} where is a model constant (=1 for Gularte's (1978) formula and =1/2 for Parchure's (1984) formula). First, the bed erosive strength profile _s(Z) is adjusted by forcing the turbulent transport model with measured erosion rates. Second, three procedures are suggested to determine the erosion rate formula coefficients _f and : a global procedure and two different layer-by-layer procedures. Each procedure is applied to an erosion experiment conducted in a rotating annular flume by Villaret and Paulic (1986). The use of the layer-by-layer procedure based on a least squares fitting technique provides a closer fit than the global procedure. The present study points out the complementarity of experimental and numerical approaches and also suggests possible improvements in laboratory test procedures.     

随钻测录井地质导向二维分解实时绘图方法

根据随钻测录井实时地质导向和大斜度、水平井评价成图技术需求，针对传统绘图方法存在的弊端，提出了将测录井信息、井眼轨迹和地质模型进行二维分解的实时绘图方法。针对二维分解绘图方法绘图时空复杂度较高的问题，给出了不同事件驱动下的局部实时计算和拷屏重绘算法，控制了对CPU和内存的消耗、提高了绘图效率，消除了实时绘图的闪烁和卡顿现象。应用实例表明，二维分解实时绘图方法能够实现大尺度随钻测录井地质导向图形的流畅、无卡顿实时绘图，可提高大斜度、水平井储层模型评价的刻画精度和时效。     

Semi-analytical solutions of a contaminant transport equation with nonlinear sorption in 1D

A new method to determine semi-analytical solutions of one-dimensional contaminant transport problem with nonlinear sorption is described. This method is based on operator splitting approach where the convective transport is solved exactly and the diffusive transport by finite volume method. The exact solutions for all sorption isotherms of Freundlich and Langmuir type are presented for the case of piecewise constant initial profile and zero diffusion. Very precise numerical results for transport with small diffusion can be obtained even for larger time steps (e.g., when the Courant-Friedrichs-Lewy (CFL) condition failed).     

Performance of Mortar and Chemical Grout Injection into Surrounding Soil When Slurry Pipe-jacking Method is Used

Small-diameter shallow tunnels are often being built by using the slurry pipe-jacking method. This system involves the pushing or thrusting of a drivage machine and concrete pipes into the ground. Chemical grout injection into the surrounding soil around the tunnel is carried out after the drivage and pushing processes are finished. The purpose of the chemical grout injection is to maintain permanent stability of the surrounding soil. However, the behavior of the chemical grouting material in the surrounding soil around the tunnel and the amount of optimum injection is not clearly understood. From these points of view, this paper discusses the performance of the chemical grouting material, when it is injected into the surrounding soil around the tunnel, by means of 2-D Eulerian–Lagrangian seepage analysis. Moreover, the effectiveness of the chemical grout injection was evaluated by using the non-linear finite element method. This investigation show when the range of the grouted zone is designed; it is necessary that the relationship between Young’s modulus of the soil/grouted zone and the confining stress be taken into consideration in order to establish effective, economical and safe chemical grout injection system. Understanding the performance of the seepage/dispersion behavior of the chemical grout and the characteristics of soil/ grouted zone is also important.     

Towards a method for postcolonial development geography? Possibilities and challenges

In this paper we explore the contours of a 'method' for postcolonial development geography, which makes it possible to imagine another 'world-picturing'. We suggest three steps towards such a method. First, we propose that a postcolonial method involves thinking about why we are doing research in the south in the first place; how we come to and produce our questions; and how we analyze and represent our findings based on our subject positionings. Second, that we need to recognize theorization as an inherent part of method, rethink how we currently theorize and reconfigure our methods of theorization to address wider political aims. Problematizing theorization helps challenge the universalism of Eurocentric theories, thus enabling development geography to move towards more decolonized versions and visions. Finally, that this must be accompanied by firmer recognition of our multiple investments – personal, institutional and geopolitical – and how they frame the possibilities for change. These are some possible steps that we think can reconfigure the 'scholarly track' that postcolonial development geographers traverse.