A hybridized numerical and regression method for estimating the minimum rock pillar width of twin circular tunnels

Twin tunnels can be used for many applications. Interaction between two tunnels is an important problem in tunnel engineering that should be studied specially. Numerical investigations are well adapted to field data and numerical methods can be used in design of rock pillar of twin circular tunnels. So far, no relationship has been provided to estimate the minimum stable rock pillar width. In this paper, the interaction between twin circular tunnels has been studied using 2D finite element analysis. To do this, a great number of twin tunnels were modeled in Phase2 software with different conditions of rock mass (RMR value) and depth of tunnel. Models were analyzed and minimum stable rock pillar width was determined. This process was repeated for three different ratios of K (ratio of horizontal stress to vertical stress, 0.5, 1, and 1.5). Finally, according to the linear and nonlinear regression methods, the best merit function was fitted to result of numerical analysis. Then, new approximate formula was proposed to estimate the minimum rock pillar width according to RMR value and depth of twin circular tunnels with different K values. The formulae are very accurate (coefficient of correlation equals to minimum 0.96) that can be used for estimating the minimum rock pillar width of twin circular tunnels.     

A semi-distributed groundwater recharge model for estimating water-table and water-balance variables

A semi-distributed groundwater recharge model is presented, which estimates water-table fluctuation and water-balance variables. The model is expressed by the water-balance concept linking atmospheric and hydrogeological parameters to different water uses (industrial, agricultural, domestic, etc). It was calibrated and validated using 5 years of data collected in the Dogo Plain in Japan. A 3-year dataset, from 2000 to 2002, was used in the calibration, while a 2-year dataset, from 2003 to 2004, was used for the validation. Calibration of the model was achieved by the shuffled complex evolution automatic optimization of model parameters to match simulated results with measured water-table depth. Square roots of relative error (R²) are 0.88 and 0.90 for calibration and validation processes, respectively. Monthly evolution of water storage change was then estimated and the water-table drawdown in different pumping scenarios was simulated. Finally, the groundwater-pumping amount planned by the government for future sustainable groundwater utilization was evaluated. The government-planned groundwater-pumping amount is feasible in most regions while the midstream region should be paid more attention. This study offers a scientific basis to control and prevent depletion of groundwater resources.     

Comparison of FFNN and ANFIS models for estimating groundwater level

Prediction of water level is an important task for groundwater planning and management when the water balance consistently tends toward negative values. In Maheshwaram watershed situated in the Ranga Reddy District of Andhra Pradesh, groundwater is overexploited, and groundwater resources management requires complete understanding of the dynamic nature of groundwater flow. Yet, the dynamic nature of groundwater flow is continually changing in response to human and climatic stresses, and the groundwater system is too intricate, involving many nonlinear and uncertain factors. Artificial neural network (ANN) models are introduced into groundwater science as a powerful, flexible, statistical modeling technique to address complex pattern recognition problems. This study presents the comparison of two methods, i.e., feed-forward neural network (FFNN) trained with Levenberg–Marquardt (LM) algorithm compared with a fuzzy logic adaptive network-based fuzzy inference system (ANFIS) model for better accuracy of the estimation of the groundwater levels of the Maheshwaram watershed. The statistical indices used in the analysis were the root mean square error (RMSE), regression coefficient (R ²) and error variation (EV).The results show that FFNN-LM and ANFIS models provide better accuracy (RMSE = 4.45 and 4.94, respectively, R ² is 93% for both models) for estimating groundwater levels well in advance for the above location.     

北京亦庄轻轨工程场地水位下降引起地面沉降量的评估方法探讨

地下水大量抽取所引起的地面沉降,是工程建设场地地质灾害危险性评估中最重要的地面变形灾种之一.由于场地情况各异,目前的定量评估尚无通用模式.一种基于区域水位下降量和相应地面沉降量拟合反演区域骨架成分弹性储水因子和非弹性储水因子的最小二乘方法已经提出.利用该方法反演出北京亦庄轻轨工程建设场地的代表性骨架成分弹性储水因子和非弹性储水因子.在此基础上,采用有效应力法对该场地的地面沉降趋势进行了预测评估.结果表明:如果未来地下水抽取状况不能得到实质性的控制,该场地东南部区域2006-2015年可能新增高达70～126 mm的地面沉降.     

A simple graphical method for estimating the components of the fault-slip vector

A simple calculation of the components of the total slip vector (D) on a fault plane allows the relationships between the magnitudes of the three slip components of D, the lateral horizontal displacement (L), the transversal horizontal displacement (T) and the vertical offset (V), to be determined. The contribution of each slip component to the total slip can be plotted jointly in a ternary diagram, assuming a unit length of the vector modulus and a suitable normalization for D. Each component equals the magnitude of D at the vertices of the diagram, hence it is possible to estimate the percentage contribution of each slip component to the total movement of a fault or a set of faults. The dip of the fault surface and the rake of the slickenlines are the input data required for displaying L, T and V relationships in these diagrams. This information may be useful in the analysis of movement geometry for different fault populations and in the determination of D by measuring just one of the fault-slip components, such as vertical slip associated with a fault scarp.     

A method for estimating casualties due to the tsunami inundation flow

This study develops a method for estimating the number of casualties that may occur while people evacuate from an inundation zone when a tsunami has inundated an area. The method is based on a simple model of hydrodynamic forces as they affect the human body. The method uses a Tsunami casualty index (TCI) computed at each grid point of a numerical tsunami model to determine locations and times within the tsunami inundation zone where evacuation during the tsunami inundation is not possible and therefore where casualties are likely to occur. The locations and times can be combined with information about population density to compute the potential number of casualties. This information is useful in developing tsunami evacuation routes that avoid such locations. To illustrate the method, it is applied to the Seattle waterfront in Washington State, USA, that is under the threat of possible tsunami disasters due to Seattle Fault earthquakes. Preliminary results suggest that the tsunami casualties may occur within the Seattle waterfront for 15 min, during the time interval from 3 to 18 min after a large Seattle Fault tsunami is generated when the background tide level is mean high water.     

一种可增加海岛地下淡水资源储量的方法研究

淡水透镜体作为海岛上珍贵的地下淡水资源,对于满足居民生活用水与维护生态系统具有重要作用,增加海岛地下淡水资源储量可有效缓解海岛地区普遍存在的水资源短缺问题。本研究提出通过在海岛外部区域采用低渗透性介质材料增加海岛地下淡水资源储量的方法,采用室内物理模型实验与基于变密度地下水流溶质运移模型的数值模拟相结合的方法对提出方法的有效性进行了验证,并通过野外尺度的数学模型分析工程实施可能性。实验与数值模拟结果较吻合,表明该方法具有抵御海水入侵、增加海岛地下淡水资源储量的巨大潜力。通过基于野外尺度的数值模拟分析工程实施的可能性,发现对于降雨入渗补给强度为0.005 7 m/d、长度为200 m,孔隙度为0.3的狭长形均质海岛,地下淡水储量为66.5 m3/m,在海岛外部区域采用渗透系数为1 m/d、厚度为5 m的低渗透性介质材料后,淡水透镜体经过约8 a时间可再次达到稳态,地下淡水储量为343.8 m3/m,增加约4倍,工程实施具备一定可能性。本研究为缓解海岛地区缺水问题、实现淡水资源可持续利用提供了一种新方法。     

A catchment water balance model for estimating groundwater recharge in arid and semiarid regions of south-east Iran

This paper presents a new model of the rainfall-runoff-groundwater flow processes applicable to semiarid and arid catchments in south-east Iran. The main purpose of the model is to assess the groundwater recharge to aquifers in these catchments. The model takes into account main recharge mechanisms in the region, including subsurface flow in the valley alluvium in mountainous areas and recharge from the bed of ephemeral rivers. It deals with the effects of spatial variation in the hydrological processes by dividing the catchment into regions of broad hydrologic similarity named as highland, intermediate and aquifer areas. The model is based on the concept of routing precipitation within and through the catchment. The model has been applied to the Zahedan catchment and the results indicate that the groundwater level estimated by the recharge model generally is in agreement with the behaviour of groundwater levels in observation wells. The sensitivity analysis indicates that when the rainfall in the aquifer area is used to replace the values recorded in the intermediate area and the highland area, the recharge estimates are reduced by 42-87%. This result supports the division of the catchment into different zones of hydrological similarity to account for spatial variability of hydrological processes. Electronic Publication     

斑岩型铜矿床成矿斑岩岩浆氧化状态研究方法综述

近年来,成矿斑岩岩浆的氧化状态对斑岩铜矿床成矿潜力和成矿规模的控制作用受到了矿床学家的广泛关注。文章总结了斑岩型铜矿床成矿斑岩岩浆氧化状态的主要研究方法及各自的适用条件:(1)钛铁氧化物(钛铁矿-磁铁矿)固熔体的组成,适用于含共生岩浆成因钛铁矿-磁铁矿的斑岩体;(2)岩石中的Fe~(3+)/Fe~(2+)含量比值,适用于新鲜的熔融包裹体或未发生热液蚀变和地表风化作用的新鲜岩石;(3)黑云母中的Fe~(3+)、Fe~(2+)和Mg含量,适用于黑云母与磁铁矿和钾长石共生的岩体;(4)角闪石主量元素含量,适用于温度为550～1120℃、压力1200 MPa、氧逸度(f(O2))为-1≤ΔNNO≤+5的钙碱性喷出岩或浅成侵入岩;(5)锆石Ce~(4+)/Ce~(3+)比值;(6)锆石EuN/EuN*比值,斑岩铜矿成矿斑岩为中酸性岩体,其中锆石普遍发育,因此被广泛用于确定岩浆氧化状态。文章还通过收集中国冈底斯成矿带、金沙江-红河成矿带、中甸岛弧成矿带、环太平洋成矿域和中亚成矿域主要斑岩铜矿床成矿斑岩岩浆氧逸度资料,讨论岩浆演化状态对斑岩型铜矿床成矿作用和成矿规模的控制作用,发现同一成矿带内含矿斑岩的氧化状态明显高于不含矿斑岩,且含矿斑岩的氧化状态与斑岩铜矿床的成矿规模具有正相关性。     

天津市地下水开采对地面沉降影响的多元回归分析

地下水的过量开采是天津市引起地面沉降的主要原因。因此天津市提出了“压缩地下水开采量”、“地下水人工回灌”、“调整地下水开采层次”等控制地面沉降的3大技术措施。经过多年的努力,控制地面沉降效果明显。如何解决地下水开发与控制地面沉降的关系,更好的贯彻这3大技术措施,是该文编写的初衷。即在开采同样地下水量的情况下,如何使地面沉降量最小;或在地面沉降量容许的情况下,如何开采最大量的地下水。压缩地下水开采量是治理地面沉降的根本措施,亦即如何压缩采水量或调整开采层次会达到最好效果。论文对天津市某区各个地下水开采层的多年累计开采量、累计沉降量进行数据统计分析,建立了该地区累计沉降量及各个地下水开采层的多元相关方程。在此基础上,分析了各个地下水开采层对地面沉降影响的相关程度。以此为该区控制地面沉降的提供依据。     

A homogenization method for estimating the bearing capacity of soils reinforced by columns

The ultimate bearing capacity problem of a strip foundation resting on a soil reinforced by a group of regularly spaced columns is investigated in the situation when both the native soil and reinforcing material are purely cohesive. Making use of the yield design homogenization approach, it is shown that such a problem may be dealt with as a plane strain yield design problem, provided that the reinforced soil macroscopic strength condition has been previously determined. Lower and upper bound estimates for such a macroscopic criterion are obtained, thus giving evidence of the reinforced soil strong anisotropy. Performing the upper bound kinematic approach on the homogenized bearing capacity problem, by using the classical Prandtl's failure mechanism, makes it then possible to derive analytical upper bound estimates for the reinforced foundation bearing capacity, as a function of the reinforced soil parameters (volume fraction and cohesion ratio), as well as of the relative extension of the reinforced area. It is shown in particular that such an estimate is closer to the exact value of the ultimate bearing capacity, than that derived from a direct analysis which implicitly assumes that the reinforced soil is an isotropic material. Copyright © 2005 John Wiley & Sons, Ltd.     

A simple Monte Carlo method for estimating the chance of a cyclone impact

Natural Hazards - Cyclones endanger life and cause great financial impact on interior and coastal regions through the destruction of buildings and land. Governments need to have a way of estimating...     

一种长期观测资料确定弱透水层参数的方法

弱透水层是含水层系统的重要组成部分,要准确计算弱透水层释水量和变形量需事先确定弱透水层的渗透系数和贮水率值。基于一维含水层系统概念模型,在相邻含水层降深随时间线性增大的边界条件下,推得了无量纲形式的弱透水层降深解析解,分析了弱透水层中滞后降深消散规律。根据水量均衡方程得到了弱透水层累计压缩变形量随时间变化的标准曲线,并提出了一种配线法用以确定弱透水层的渗透系数和贮水率,该配线法能够反映弱透水层释水变形过程的滞后性。以上海含水层系统为例,运用配线法确定了f_(10-7)分层标处第2弱透水层的渗透系数为4.26×10~(-10)m/s,贮水率为2.22×10~(-4)m~(-1)。对于具有长序列变形和水位观测资料的含水层系统,该方法具有一定的适用性。     

由土体级配近似确定土-水特征曲线的一种方法

利用毛细管理论推导了特定粒径颗粒堆积物中毛细水的上升高度,据此建立了土体级配与非饱和土土-水特征曲线的联系,构造了一个近似确定土-水特征曲线的新的物理经验模型。对大部分土而言,模型中引入的修正参数ouR与吸力水头h在对数坐标下呈现明显的线性相关性,可以使用ouln R?aln(h/m)?b进行拟合;利用非饱和土数据库UNSODA中406种土样的测量数据(包括干燥过程的土-水特征曲线和级配曲线)对拟合参数a、b进行了参数分析,统计了a、b的分布规律;计算显示,a、b与级配和孔隙比无关,可能受矿物组成影响。利用提出的模型进行预测时,可以用矿物组成类似的土样试验结果计算a、b值以确定修正参数ouR,在资料缺乏时也可使用统计得到的a、b平均值。该模型为间接确定土-水特征曲线提供了思路。     

A quantitative assessment of groundwater resources in the Middle East and North Africa region

The Middle East and North Africa (MENA) region is the world’s most water-stressed region, with its countries constituting 12 of the 15 most water-stressed countries globally. Because of data paucity, comprehensive regional-scale assessments of groundwater resources in the MENA region have been lacking. The presented study addresses this issue by using a distributed ArcGIS model, parametrized with gridded data sets, to estimate groundwater storage reserves in the region based on generated aquifer saturated thickness and effective porosity estimates. Furthermore, monthly gravimetric datasets (GRACE) and land surface parameters (GLDAS) were used to quantify changes in groundwater storage between 2003 and 2014. Total groundwater reserves in the region were estimated at 1.28 × 10⁶ cubic kilometers (km³) with an uncertainty range between 816,000 and 1.93 × 10⁶ km³. Most of the reserves are located within large sedimentary basins in North Africa and the Arabian Peninsula, with Algeria, Libya, Egypt, and Saudi Arabia accounting for approximately 75% of the region’s total freshwater reserves. Alternatively, small groundwater reserves were found in fractured Precambrian basement exposures. As for groundwater changes between 2003 and 2014, all MENA countries except for Morocco exhibited declines in groundwater storage. However, given the region’s large groundwater reserves, groundwater changes between 2003 and 2014 are minimal and represent no immediate short-term threat to the MENA region, with some exceptions. Notwithstanding this, the study recommends the development of sustainable and efficient groundwater management policies to optimally utilize the region’s groundwater resources, especially in the face of climate change, demographic expansion, and socio-economic development.     

A method for estimating crack-initiation stress of rock materials by porosity

Crack-initiation stress of a rock under compression is the stress level that marks the initiation of the rock microfracturing process or in other words, the onset of new damage to the rock. This paper proposed a simple methodology with justifications to explore the feasibility of using total and effective porosities as estimators of crack-initiation stress of brittle crystalline rock materials under uniaxial compression. The validity/applicability of the proposed method was examined by an experimental study of granitic materials from Malanjkhand, Madhya Pradesh. It was found that effective porosity depicts better correlation with crack-initiation stress than with uniaxial compressive strength of the granitic materials. On the other hand, total porosity does not show any perceptible correlation with uniaxial compressive strength and crack-initiation stress. Plausible reasons for the nature of the obtained results were also explained in view of rock failure process under compression. It is concluded that following the proposed method, effective porosity can be used as a physical index to obtain a quick estimate of crack-initiation stress of the investigated rocks empirically.     

回归分析法在日变数据推算中的应用

在海洋磁测数据日变改正过程中,常会因各种因素限制,导致日变数据缺失,这时就需要结合多台站数据推算工区位置处的日变数据。通过借鉴前人研究成果及考察相关分析结果,可以近似认为台站间日变数据具有一定的线性关系,并引入统计学中常用的回归分析法拟合出某一位置日变数据的推算公式,进而得到推算数据。选取南海区域实测数据验证可知该方法具有一定的可靠性,可以解决日变数据缺失等问题,从而提升海洋磁测数据的精度,是一种改进的磁测数据日变改正方法。     

一种新的预测方法在地下水动态预报中的应用

通过实例介绍一种新的预测方法,用来处理含有时变参数的预测模型,采用对时变参数建模和预测,改善了预测的精度。     

一种新的岩浆岩分类定量方法

目前,岩浆岩的超基性、基性、中性、酸性的分类均根据SiO2的含量,但这种单一含量判别标准并不严谨,含量经常与分类不完全对应。使用TraceElem 1.0软件对各种岩浆岩进行逐步判别分析、聚类分析和对应分析研究,据此认为超基性岩由MgO和FeO组成的因子确定,基性岩则由P2O5、Fe2O3、TiO2、CaO、MnO组成的因子确定,中性岩由Na2O和Al2O3组成的因子确定,酸性岩由K2O和SiO2组成的因子确定。岩浆岩的分类宜以SiO2为主、以MgO和CaO为辅,尤其要引入MgO。在SiO2含量相同的情况下,MgO、CaO含量越高,基性程度越强。基于这一分析结果,提出一种新的酸度指数（ADI)计算方法,即ADI=w(SiO2)-0.75w(MgO)-0.23w(CaO),ADI<38.0%为超基性岩,在38.0%～52.0%之间为基性岩,在52.0%～62.5%之间为中性岩,>62.5%为酸性岩。