GIS-based spatial and temporal prediction system development for regional land subsidence hazard mitigation

An integrated GIS-based approach for establishing a spatial and temporal prediction system for groundwater flow and land subsidence is proposed and applied to a subsidence-progressed Japanese coastal plain. Various kinds of fundamental data relating to groundwater flow and land subsidence are digitized and entered into a GIS database. A surface water hydrological cycle simulation is performed using a GIS spatial data operation for the entire plain, and the spatial and temporal groundwater infiltration quantity is hereby obtained. Through the data transformation from the GIS database to a groundwater flow code (MODFLOW), a 3D groundwater flow model is established and unsteady groundwater flow simulation for the past 21 years is conducted with results which compare satisfactorily with observed results. Finally, a Visual Basic code is developed for land subsidence calculations considering aquifer and aquitard deformation. Future land subsidence in the plain is predicted assuming different water pumping scenarios, and the results provide important information for land subsidence mitigation decision-making.     

Prediction of in-situ block size distributions with reference to armourstone for breakwaters

Understanding a quarry in terms of its potential for breakwater construction materials presents a special challenge for the engineering geologist. Unlike blasting in aggregates and mining operations, optimisation of the extraction process has a focus on the potential for production of large blocks for armourstone. These blocks weighing many tonnes are used for cover layers to resist wave action. The quarry-run is used for breakwater core. If the quarry has been developed as a source of materials dedicated to a breakwater construction project, the success of the project depends greatly on the blasting and production of rock sizes that are required and the avoidance of leaving a massive quantity of unused materials behind in the quarry after project completion. Prediction of in-situ block sizes such as from joint spacing data, provides the most critical input for the prediction of the blast pile block size distribution (BBSD), which in turn is a vital early design input if the constructed breakwater is to be economical as well as effective.This paper is part of a series of papers that introduces the coastal engineering motivation for this work on engineering geology, giving reasons why the prediction of the fragmentation curve of the blast products in a dedicated quarry is of such economic importance for breakwater projects. The first step towards blasted block size distribution (BBSD) prediction is the prediction of the in-situ block sized distribution (IBSD), the main subject of this paper. Drawing together research methods from the 1990s and the rock mechanics principles of discontinuity analysis, a practical step by step methodology for IBSD assessment that includes approaches that are not reliant on specialised computer software is presented. Continuing on the practical theme, a new extension of the volumetric joint count approach is suggested for IBSD prediction for the case when sparse borehole data is all that is available. A case study of IBSD assessment and the associated BBSD and blast assessment is presented from a Carboniferous limestone quarry. For clarity, details of blast design and yield curve prediction that are recommended for use in the context of armourstone production, have been presented in a companion paper. The Rosin-Rammler equation is used as an example form for the BBSD prediction of a dedicated quarry and the potential for breakwater project optimisation is illustrated. The final section sets out a method for directly comparing yield curves together with the demand for materials set by the breakwater design. On the same plot, sizes where there is a relative shortfall in production can be identified. The dependence of effective breakwater design on accurate quarry yield prediction and quarry blasting performance is discussed.     

A model for the constant-head pumping test conducted in vertically fractured media

An analytical model for the constant-head pumping test is developed for a partially penetrating well that has a finite thickness skin, and intersects a single vertical fracture. In the model, the fracture is fully confined and flow occurs only in the fracture. The model is developed using Laplace transform and finite Fourier transform methods. The model is to be used for analysing well test data from vertically fractured media and for verifying numerical models. Dimensionless curves are used to study the effects of a finite thickness skin and a partially penetrating wellbore. In the presence of a finite thickness skin, or a partially penetrating wellbore, a typical flow response for the constant-head pumping test has three distinct periods of flow corresponding to small-, intermediate- and large-time. Small- and large-time approximations are presented for the model. For tests where the wellbore is fully penetrating, or the partial penetration ratio is known, these approximations can be used to analyse field data.     

A semi-analytical method for the wave-induced seabed response

A general semi-analytical method is presented for the analysis of seabed response under wave action during a storm. The seabed is idealized as a poro-elastic medium filled with a single compressible fluid with anisotropic flow. The coupled process of fluid flow and deformation of soil skeleton is formulated in the framework of Biot's theory. The analysis for the response of homogeneous seabed of finite thickness under a plane progressive wave is developed first, followed by an extension for the case of a layered seabed. A generalization for three-dimensional response of seabed is also developed for a general wave field which provides the analyses for seabed response under short-crested or standing waves in the vicinity of a structure. Some numerical examples illustrating the proposed analyses are also presented.     

A differential slice approach to the problem of retaining wall loading

A differential slice technique is applied in order to obtain the solution for the pressure distribution on rigid retaining walls. The technique is based on a statical analysis of a plane differential slice, for which only the global equilibrium is required. An analytical solution to the problem is found for a non-cohesive material and a linear slip surface. For more complicated cases the numerical solution is required.     

Thermoelastic stress due to a rectangular heat source in a semi-infinite medium. Presentation of an analytical solution

The thermoelastic response due to a time-dependent rectangular heat source in a semi-infinite medium is analyzed. The problem originates from studies of nuclear waste repositories in rock. Canisters containing heat-emitting nuclear waste are deposited over a large rectangular area deep below the ground surface. The solution for a time-dependent heat source is obtained from the corresponding instantaneous heat source by superposition. The thermoelastic problem for the instantaneous rectangular heat source in a infinite surrounding is solved exactly. An important step is the introduction of so-called quadrantal heat sources. The solution for the rectangle is obtained from four quadrantal solutions. The solution for the quadrantal heat source depends on the three dimelasionless coordinates only. Time occurs in the scale factors only. The condition of zero normal and shear stresses at the ground surface is fulfilled by using a mirror heat source and a boundary solution. The boundary solution accounts for the residual normal stress at the ground surface. Using a Hertzian potential, a surprisingly simple solution is obtained. The final analytical solution is quite tractable considering the complexity of the initial problem. The solution may be used to test numerical models for coupled thermoelastic processes. It may also be used in more detailed numerical simulations of the process near the heat sources as boundary conditions to account for the three-dimensional global process.     

Dynamic interaction between the soil and an anchored sheet pile during seismic excitation

A subdomain approach for dynamic soil–structure interaction is proposed for the linear elastic seismic analysis of an anchored sheet pile, retaining a horizontally layered soil on rigid bedrock. A hybrid solution technique is used, employing a finite element formulation for the generalized sheet pile, a thin layer formulation for the soil and a direct stiffness formulation for the tieback; the displacement vectors of the sheet pile and the soil are decomposed, using the eigenmodes of the sheet pile and the propagating or decaying modes in the soil. The discretization can be limited to the interface(s), where pointwise continuity of the displacements is enforced, whereas a weak variational formulation is used for the stress equilibrium. The solution technique is illustrated by means of a numerical example, where the harmonic response of a flexible anchored sheet pile is considered and compared to the case where no tieback is present. Copyright © 2002 John Wiley & Sons, Ltd.     

非承压完整或不完整井稳定流

本文根据现有的实验资料说明裘布依假定适用于虚构流网,故所得出的自由水面方程和流量方程也应适用于虚构流网。根据虚构流网概念,获得了完整井或非完整井抽水时流量方程。另一方面,用分析方法获得不完整井抽降不大时的流量方程;利用室内实验资料对方程中的参变数值编成曲线图,并说明此方程的精度亦较一些经验公式为高。     

A theoretical method for determining sample mass in a sieving test

Obtaining a representative particle size distribution for soil is a common challenge in earth works and is affected by the size of sieving samples. While the current standards usually specify a minimum sample mass, there is no scientific justification for the specification. Treating the preparation of sieving samples as a process of random sampling, a new method is proposed for determining the minimum mass of a sieving test sample. The proposed method is validated via laboratory tests and will improve standard specification and engineering practice.     

Rapid solution of kriging equations,using a banded Gauss elimination algorithm

Summary A crucial concern when implementing computer algorithms for geostatistical analyses on microcomputers is speed of execution. Kriging, in particular, typically relies on a Gauss elimination algorithm to solve for weights. Because such an alogrithm is required for each estimate, the solution for weights can result in very slow program execution speed on a microcomputer. One approach to enhancing the efficiency of Gauss elimination is demonstrated herein. The upper triangle plus diagonal of the intersample covariance matrix is used in a modified banded Gauss elimination algorithm. Results show that such an algorithm yields approximately a two-fold reduction in execution time for kriging when the number of nearest neighbours used for estimation is large.     

Seismic velocity structure and gravity anomalies: a comparison

The question was examined as to whether the same gravity anomaly is produced for a range of crustal velocity structures all of which produce similar seismic record sections. The results indicate that the maximum errors in the computed gravity anomalies for the various velocity structures is around 20–30 mGal for some models and is around 50 mGal for many others. A major source of error is underestimating the effect of a seismic low-velocity zone which is at one end of the correct velocity structure and which was not detected by several of the interpretations presented at a recent workshop. If no low-velocity layer is included, the error in the gravity anomaly is 30 mGal. The choice of a particular velocity-density relationship does not seem to be a serious problem in the analysis, except for the case of the low-velocity zone, as long as we use a continuous velocity-density curve.     

Transfer matrix approach for nonlinear pile group response analysis

A transfer matrix method is applied for the analysis of non-linear pile group responses. The expression for the transfer matrix is obtained by idealizing the non-linear pile group as a group of piles attached to a piecewise linear “Winkler model for a pile group”. This Winkler idealization is essential to apply a transfer matrix method for the pile group response analysis. The parameters of this Winkler model can be defined from unit load transfer curves obtained for a single pile. In the limited studies carried out, it is found that the present approach predicts the response of pile groups reasonably well.     

Food expenditure and economic development

In this article Earnst Engel's statements about the relationship between food expenditure are investigated for 80 countries. Food expenditure as a percentage of all expenditure is shown to have a distinctive geographical distribution, and is related to Gross National Product per capita, although not in a simple linear manner. Historical data for the percentage are discussed and a decline over time and with increasing income is observed. However for some periods of income growth there is no decline and some possible reasons for this are discussed.     

The entrainment factor in froth flotation: Model for particle size and other operating parameter effects

Accurately estimating entrainment is crucial when predicting flotation performance as it is essential for determining the concentrate grade achieved. It has been found previously that the amount of gangue entrained is proportional to the water recovery; this proportionality is referred to as the entrainment factor. Experimentally it has been found that entrainment is a strong function of particle size, as well as being dependent on other cell operating parameters such as froth depth and air rate.A simplified theoretical model for entrainment is developed which includes the effects of liquid motion and content, particle settling and particle dispersion. First, a detailed one-dimensional differential model for the entrainment factor is developed and solved numerically. Thereafter, a simplified analytical expression for the entrainment factor is produced which is a good approximation to the more detailed one-dimensional model. Both these models are shown to predict closely experimental trends for entrainment as a function of particle size and froth depth.     

FOSM在水平场地液化概率评价中的应用

为了更好地进行场地液化评价,将可靠度理论引入水平场地液化概率评价中。以标准贯入试验(SPT)实测数据的统计分析结果为基础,用一次二阶矩法(FOSM)建立水平场地液化概率评价模型,分析了测试数据变异系数对抗液化安全系数与液化概率的影响,并建议了水平场地液化概率评价标准。实例分析表明,新建水平场地液化概率评价模型各参数的物理意义与统计指标明确,相比传统的确定性分析方法,不仅能判定液化的发生与否,还能给出液化发生的概率,这为进行基于风险分析的抗震设计提供了可能。     

岩石统计渗流模型和统计损伤本构模型研究

采用Eshelby等效夹杂方法建立考虑渗流的岩石损伤本构模型是一种有效方法,但相关文献目前还极少。利用细观力学的Eshelby等效夹杂方法, 探索了考虑渗流和损伤的Helmholtz自由比能函数的确定,用连续介质损伤力学方法建立了相应的考虑渗流的岩石损伤统计本构模型,提出了考虑渗流和损伤过程的岩石破坏准则,建议了考虑损伤和应变的岩石渗透系数演化方程。与试验结果比较表明,所建立模型是合理的。     

A Deep-Learning-Based Geological Parameterization for History Matching Complex Models

A new low-dimensional parameterization based on principal component analysis (PCA) and convolutional neural networks (CNN) is developed to represent complex geological models. The CNN–PCA method is inspired by recent developments in computer vision using deep learning. CNN–PCA can be viewed as a generalization of an existing optimization-based PCA (O-PCA) method. Both CNN–PCA and O-PCA entail post-processing a PCA model to better honor complex geological features. In CNN–PCA, rather than use a histogram-based regularization as in O-PCA, a new regularization involving a set of metrics for multipoint statistics is introduced. The metrics are based on summary statistics of the nonlinear filter responses of geological models to a pre-trained deep CNN. In addition, in the CNN–PCA formulation presented here, a convolutional neural network is trained as an explicit transform function that can post-process PCA models quickly. CNN–PCA is shown to provide both unconditional and conditional realizations that honor the geological features present in reference SGeMS geostatistical realizations for a binary channelized system. Flow statistics obtained through simulation of random CNN–PCA models closely match results for random SGeMS models for a demanding case in which O-PCA models lead to significant discrepancies. Results for history matching are also presented. In this assessment CNN–PCA is applied with derivative-free optimization, and a subspace randomized maximum likelihood method is used to provide multiple posterior models. Data assimilation and significant uncertainty reduction are achieved for existing wells, and physically reasonable predictions are also obtained for new wells. Finally, the CNN–PCA method is extended to a more complex nonstationary bimodal deltaic fan system, and is shown to provide high-quality realizations for this challenging example.

     

Climate and solar signals in property damage losses from hurricanes affecting the United States

The authors show that historical property damage losses from US hurricanes contain climate signals. The methodology is based on a statistical model that combines a specification for the number of loss events with a specification for the amount of loss per event. Separate models are developed for annual and extreme losses. A Markov chain Monte Carlo procedure is used to generate posterior samples from the models. Results indicate the chance of at least one loss event increases when the springtime north–south surface pressure gradient over the North Atlantic is weaker than normal, the Atlantic ocean is warmer than normal, El Ni?o is absent, and sunspots are few. However, given at least one loss event, the magnitude of the loss per annum is related only to ocean temperature. The 50-year return level for a loss event is largest under a scenario featuring a warm Atlantic Ocean, a weak North Atlantic surface pressure gradient, El Ni?o, and few sunspots. The work provides a framework for anticipating hurricane losses on seasonal and multi-year time scales.     

Irrigated area determination: a case study in the Province of San Juan,Argentina

Much of the central-western region of Argentina, where San Juan Province is located, experiences arid to semi-arid climatic conditions with low average annual rainfall accompanied by substantial evapotranspiration. Consequently, a viable crop industry depends to a large extent upon irrigation from major river systems. Increasing demand for water in the lower basin of the San Juan River is emphasizing the need for more accurate estimates of water used for irrigation. Since the water demand for a particular crop is very closely related to crop area, monitoring the area of crop under irrigation is considered a proxy for the amount of water used. Landsat 5 imagery for the growing season, field data and aerial photographs were used to evaluate crop area.