三维体元拓扑数据模型的改进与实验

在简要介绍三维体元拓扑数据模型建模原理的基础上,分析了三维体元拓扑数据模型的不足,并从处理含夹层地质体和由非平行剖面构建地质体两个方面,改进了三维体元拓扑数据模型的建模条件和数据结构。实验表明,改进后的数据模型更加适合基于剖面的三维地质建模。      

Automatic calibration of HEC‐HMS using single‐objective and multi‐objective PSO algorithms

This study presents single‐objective and multi‐objective particle swarm optimization (PSO) algorithms for automatic calibration of Hydrologic Engineering Center‐ Hydrologic Modeling Systems rainfall‐runoff model of Tamar Sub‐basin of Gorganroud River Basin in north of Iran. Three flood events were used for calibration and one for verification. Four performance criteria (objective functions) were considered in multi‐objective calibration where different combinations of objective functions were examined. For comparison purposes, a fuzzy set‐based approach was used to determine the best compromise solutions from the Pareto fronts obtained by multi‐objective PSO. The candidate parameter sets determined from different single‐objective and multi‐objective calibration scenarios were tested against the fourth event in the verification stage, where the initial abstraction parameters were recalibrated. A step‐by‐step screening procedure was used in this stage while evaluating and comparing the candidate parameter sets, which resulted in a few promising sets that performed well with respect to at least three of four performance criteria. The promising sets were all from the multi‐objective calibration scenarios which revealed the outperformance of the multi‐objective calibration on the single‐objective one. However, the results indicated that an increase of the number of objective functions did not necessarily lead to a better performance as the results of bi‐objective function calibration with a proper combination of objective functions performed as satisfactorily as those of triple‐objective function calibration. This is important because handling multi‐objective optimization with an increased number of objective functions is challenging especially from a computational point of view. Copyright © 2012 John Wiley & Sons, Ltd.     

A conceptual–numerical model to simulate hydraulic head in aquifers that are hydraulically connected to surface water bodies

In this paper, we present a conceptual‐numerical model that can be deduced from a calibrated finite difference groundwater‐flow model, which provides a parsimonious approach to simulate and analyze hydraulic heads and surface water body–aquifer interaction for linear aquifers (linear response of head to stresses). The solution of linear groundwater‐flow problems using eigenvalue techniques can be formulated with a simple explicit state equation whose structure shows that the surface water body–aquifer interaction phenomenon can be approached as the drainage of a number of independent linear reservoirs. The hydraulic head field could be also approached by the summation of the head fields, estimated for those reservoirs, defined over the same domain set by the aquifer limits, where the hydraulic head field in each reservoir is proportional to a specific surface (an eigenfunction of an eigenproblem, or an eigenvector in discrete cases). All the parameters and initial conditions of each linear reservoir can be mathematically defined in a univocal way from the calibrated finite difference model, preserving its characteristics (geometry, boundary conditions, hydrodynamic parameters (heterogeneity), and spatial distribution of the stresses). We also demonstrated that, in practical cases, an accurate solution can be obtained with a reduced number of linear reservoirs. The reduced computational cost of these solutions can help to integrate the groundwater component within conjunctive use management models. Conceptual approximation also facilitates understanding of the physical phenomenon and analysis of the factors that influence it. A simple synthetic aquifer has been employed to show how the conceptual model can be built for different spatial discretizations, the parameters required, and their influence on the simulation of hydraulic head fields and stream–aquifer flow exchange variables. A real‐world case was also solved to test the accuracy of the proposed approaches, by comparing its solution with that obtained using finite‐difference MODFLOW code. Copyright © 2011 John Wiley & Sons, Ltd.     

Statistical inverse analysis based on genetic algorithm and principal component analysis: Method and developments using synthetic data

This study concerns the identification of parameters of soil constitutive models from geotechnical measurements by inverse analysis. To deal with the non‐uniqueness of the solution, the inverse analysis is based on a genetic algorithm (GA) optimization process. For a given uncertainty on the measurements, the GA identifies a set of solutions. A statistical method based on a principal component analysis (PCA) is, then, proposed to evaluate the representativeness of this set. It is shown that this representativeness is controlled by the GA population size for which an optimal value can be defined. The PCA also gives a first‐order approximation of the solution set of the inverse problem as an ellipsoid. These developments are first made on a synthetic excavation problem and on a pressuremeter test. Some experimental applications are, then, studied in a companion paper, to show the reliability of the method. Copyright © 2009 John Wiley & Sons, Ltd.     

尾砂胶结充填体蠕变模型及在FLAC3D 二次开发中的实验研究

关于岩石蠕变特性的研究已有诸多成果,但对胶结充填体的蠕变特性还缺乏系统地研究。在室内充填体单轴蠕变试验的基础上,利用Hoek-Kelvin模型表征充填体的蠕变特性,运用粒子群优化算法,对选用的蠕变模型的参数进行辨识,并研究各蠕变参数对应力水平的敏感程度。研究结果表明,在不同分级应力水平加载下,弹性模量EH和黏滞系数η变化较小,而参数EK对应力水平变化较敏感。利用FLAC3D软件二次开发所建立的蠕变模型,用开发的模型进行分级加载蠕变的数值模拟,计算结果与试验数据吻合。     

胜利探区复杂地质构造的地震波照明与观测系统优化

随着胜利探区勘探开发的逐步深入,主要勘探目标开始转向小断块、小砂体等微幅构造以及岩性隐蔽油气藏,传统的地震采集设计技术难以满足当前生产需求。为此,选取胜利探区复杂构造地质模型,开展基于波动方程理论的地震波照明和面向目标的观测系统优化设计技术的研究,形成了一套适合胜利探区二次采集的观测系统优化设计的技术系列。研究结果表明,该技术系列能够保证该区地质构造的形态完整,小断块、小砂体等微幅构造的成像质量也有较大幅度的提高。     

深基坑信息化施工管理的实践与体会

本文从一个工程的实践,通过方案比选、精心施工,提出了进行深基坑信息化施工的几点做法及体会,确保深基坑的施工安全和工程进度。     

An enhanced stochastic optimization in fracture network modelling conditional on seismic events

This paper presents an approach to modelling fracture networks in hot dry rock geothermal reservoirs. A detailed understanding of the fracture network within a geothermal reservoir is critically important for assessments of reservoir potential and optimal production design. One important step in fracture network modelling is to estimate the fracture density and the fracture geometries, particularly the size and orientation of fractures. As fracture networks in these reservoirs can never be directly observed there is significant uncertainty about their true nature and the only feasible approach to modelling is a stochastic one. We propose a global optimization approach using simulated annealing which is an extension of our previous work. The fracture model consists of a number of individual fractures represented by ellipses passing through the micro-seismic points detected during the fracture stimulation process, i.e. the fracture model is conditioned on the seismic points. The distances of the seismic points from fitted fracture planes (ellipses) are, therefore, important in assessing the goodness-of-fit of the model. Our aims in the proposed approach are to formulate an appropriate objective function for the optimal fitting of a set of fracture planes to the micro-seismic data and to derive an efficient modification scheme to update the model parameters. The proposed objective function consists of three components: orthogonal projection distances of the seismic points from the nearest fitted fractures, the amount of fracturing (fitted fracture areas) and the volumes of the convex hull of the associated points of fitted fractures. The functions used in the model update scheme allow the model to achieve an acceptable fit to the points and to converge to acceptable fitted fracture sizes. These functions include two groups of proposals: one for updating fracture parameters and the other for determining the size of the fracture network. To increase the efficiency of the optimization, a spatial clustering approach, the Distance-Directional Transform, was developed to generate parameters for newly proposed fractures. A simulated dataset was used as an example to evaluate our approach and we compared the results to those derived using our previously published algorithm on a real dataset from the Habanero geothermal field in the Cooper Basin, South Australia. In a real application, such as the Habanero dataset, it is difficult to determine definitively which algorithm performs better due to the many uncertainties but the number of association points, the number of final fractures and the error are three important factors that quantify the effectiveness of our algorithm.     

利用无人船测量系统检测钱塘江护岸工程水下块石

水下块石检测与识别作为钱塘江海塘护岸工程的关键环节,对保障板桩施工工效至关重要。本文首先在研究无人船测量系统岸基通信、数据采集核心技术基础上,推导了NORBIT多波束声呐分辨率估计模型及附加块石粒径约束条件的最大波束开角、最小数据更新率、最大航速间的关系式和推荐值;然后结合钱塘江水下多波束扫测点云数据三维特性,对区域生长算法进行改进,以实现块石点云识别和提取。工程实践结果表明,优化的无人船测量系统多波束声呐参数可实现水下细小块石精准检测,能如实反映水下块石及周边微地形地貌真实情况,改进的区域生长算法能从众多河床点云数据中高效提取水下块石点云,为板桩施工提供准确的块石分布情况,具有很好的工程应用意义。     

达深CP302开窗侧钻水平井钻井实践与认识

达深CP302井是大庆油田自主设计和施工的第一口深层小井眼欠平衡套管开窗侧钻水平井,该井集中了深井、小井眼井、欠平衡井、套管开窗及水平井的所有技术特点与难点。通过技术方案优化,确定了斜向器配合复式铣锥磨铣开窗方式,详细介绍了套管开窗侧钻技术和井眼轨迹控制技术。达深CP302井的钻探成功,取得了良好的经济效益和社会效益。