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1.
Analytical and numerical methods are proposed for the calculation of water inflow into construction pits under various geological—engineering and hydrogeological conditions at the construction site. Water inflow into the pit is shown to depend not only on lateral seepage but also on the leakage from underlying aquifers at appropriate parameters of their interaction. Under certain natural conditions, the most efficient method for construction pit draining at low water yield of soils in the construction area are light wellpoint systems, the capacity and layout of which is determined by the potential inflow through the pit contour. The results of analytical and numerical calculations for the assessment of groundwater inflow into a pit are given, and light wellpoint systems are shown to be effective under different combinations of natural and engineering conditions. 相似文献
2.
E. D. P. Perera K. Jinno A. Tsutsumi Y. Hiroshiro 《Stochastic Environmental Research and Risk Assessment (SERRA)》2009,23(7):957-965
The Motooka region in the Fukuoka prefecture in western Japan is a coastal area, where groundwater is utilized as the main
water resource for greenhouse agriculture and domestic use. Over-exploitation of groundwater has resulted in seawater intrusion
and thus in the contamination of the freshwater aquifer. Fluctuations in electric conductivities caused by such intrusion
are a crucial problem, since even slight changes in electric conductivities of the water used for agricultural purposes significantly
affect the crops’ growth and yield. However, no study has thus far been conducted on the electric conductivity fluctuations
caused by groundwater pumping and seasonal recharge of groundwater in the Motooka region. To this end, an attempt is made
in the present study to develop a numerical variable-density solute transport model and then apply it to simulate the electric
conductivity fluctuations with groundwater pumping and rainwater recharge. This model is developed under a finite difference
scheme, and the method of characteristics is used as the numerical technique for solving the advection term of the advection–dispersion
solute transport equation. The results from this numerical model are compared with the field measurements. 相似文献
3.
河水径向渗流会对河岸基坑稳定性及支护结构内力产生显著影响。以某深基坑工程为背景进行了三维流固耦合数值模拟分析,研究了渗流对深基坑土体及支护结构受力与变形的作用规律。研究结果表明：1初始水位时,渗流作用对土体水平应力与土体剪应力的影响较小,但水位上升后,坑底处土体水平应力明显增大,在坑壁拐角处应力集中现象突出,土体剪应力在开挖面以下的底脚处最大;2土体水平位移与竖向位移均在水位上升时呈递增趋势;3桩身弯矩与剪力在水位上升初期有较大增加,之后增长速度减小;4上层、下层锚杆的自由段和锚固段轴力在水位上升初期均有明显增加,但之后增加幅度很小;5安全系数在水位上升初期降低较多,之后以较小速度呈线性减小。 相似文献
4.
Forecasters need climatological forecasting tools because of limitations of numerical weather prediction models. In this article,
using Finnish SYNOP observations and ERA-40 model reanalysis data, low visibility cases are studied using subjective and objective
analysis techniques. For the objective analysis, we used an AutoClass clustering algorithm, concentrating on three Finnish
airports, namely, the Rovaniemi in northern Finland, Kauhava in western Finland, and Maarianhamina in southwest Finland. These
airports represent different climatological conditions. Results suggested that combining of subjective analysis with an objective
analysis, e.g., clustering algorithms such as the AutoClass method, can be used to construct climatological guides for forecasters.
Some higher level subjective “meta-clustering” was used to make the results physically more reasonable and easier to interpret
by the forecasters. 相似文献
5.
In this paper, based on the previous study of practical use of seismic regime windows and seismic regime belts, the problem
of establishing a “seismic regime network” consisting of “windows” and “belts” is further posed and discussed according to
the observed fact that many “windows” and “belts” make responses to one earthquake. For the convenience of usage, the “seismic
regime network” is divided into two classes, the first class and the second one. The former can be used in tendency prediction
for long-term seismic activity in a large area, the latter used in short-term prediction in a small area. In this paper, after
briefly discussing the physical significance of “seismic regime network”, it is pointed out that this simple and easily used
method can be used to observe and extract seismic precursory information from a large area before a great earthquake, thus
it can provide a reliable basis for the analysis and judgement of seismic regime tendency in time and space. No doult, this
method is of certain practical significance.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 161–169, 1991.
The English version of this paper is improved by Prof. Shaoxie Xu. 相似文献
6.
Global sensitivity analysis for a numerical model of radionuclide migration from the RRC “Kurchatov Institute” radwaste disposal site 总被引：1，自引：1，他引：0
E. Volkova B. Iooss F. Van Dorpe 《Stochastic Environmental Research and Risk Assessment (SERRA)》2008,22(1):17-31
Today, in different countries, there exist sites with contaminated groundwater formed as a result of inappropriate handling
or disposal of hazardous materials or wastes. Numerical modeling of such sites is an important tool for a correct prediction
of contamination plume spreading and an assessment of environmental risks associated with the site. Many uncertainties are
associated with a part of the parameters and the initial conditions of such environmental numerical models. Statistical techniques
are useful to deal with these uncertainties. This paper describes the methods of uncertainty propagation and global sensitivity
analysis that are applied to a numerical model of radionuclide migration in a sandy aquifer in the area of the RRC “Kurchatov
Institute” radwaste disposal site in Moscow, Russia. We consider 20 uncertain input parameters of the model and 20 output
variables (contaminant concentration in the observation wells predicted by the model for the end of 2010). Monte Carlo simulations
allow calculating uncertainty in the output values and analyzing the linearity and the monotony of the relations between input
and output variables. For the non monotonic relations, sensitivity analyses are classically done with the Sobol sensitivity
indices. The originality of this study is the use of modern surrogate models (called response surfaces), the boosting regression
trees, constructed for each output variable, to calculate the Sobol indices by the Monte Carlo method. It is thus shown that
the most influential parameters of the model are distribution coefficients and infiltration rate in the zone of strong pipe
leaks on the site. Improvement of these parameters would considerably reduce the model prediction uncertainty. 相似文献
7.
1 Introduction The landslides influences on the human society have become an environment difficult problem not able to be neglected, and according to the priority of harms, harms of landslides are only smaller than those from earthquakes in all sorts of natural hazards[1]. Landslide is part of rock mass, soil mass or their compound mass slides downward along a certain slid- ing surface under the actions of inner and external dy- namics, and it is one severe instability phenomenon of rock and s… 相似文献
8.
In this paper, we take occurrence process of early strong aftershocks of a main-after shock type′s earthquake sequence as a complex grey system, and introduce predicting method for its stronger aftershocks by grey predicting theory. Through inspection prediction for 1998 Zhangbei MS=6.2 earthquake sequence, it shows that the grey predicting method maybe has active significance for the investigation of quick response prediction problems of stronger aftershocks of an earthquake sequence. 相似文献
9.
In solving groundwater transport problems with numerical models, the computation time (CPU processing time) of transport simulation is approximately inversely proportional to the transport time-step size. Therefore, large time-step sizes are favorable for achieving short computation time. However, transport time-step size must be sufficiently small to avoid numerical instability if an explicit scheme is used (and to guarantee enough model accuracy if an implicit scheme is used). For a transport model involving groundwater pumping, a small transport time-step size is often required due to the high groundwater velocities near the pumping well. Small grid spacing often specified near the pumping well also limits the time-step size. This paper presents a method to increase transport time-step size in a transport model when groundwater pumping is simulated. The key to this approach is to numerically decrease the groundwater seepage velocities in grid cells near the pumping well by increasing the effective porosity so that the transport time-step size can be increased without violating stability constraints. Numerical tests reveal that by using the proposed method, the computation time of transport simulation can be reduced significantly, while the transport simulation results change very little. 相似文献
10.
The purpose of the research was to determine parameters of ground-motion models for two areas characterized by considerable
induced seismicity and different geology. Fifty-nine events collected from surface seismological stations of coal mine “Bielszowice”
(at the Main Anticline, South Poland) and 144 events from coal mine “Ziemowit” (at the Main Syncline, South Poland) were used
for computation. For both areas, simple ground-motion prediction equations (GMPEs) without site effects were derived, but
the model was acceptable only for “Bielszowice” area. The GMPE was calculated once again for “Ziemowit”, but this time we
took into consideration the amplification coefficient, which significantly improved the model solution. Finally, the theoretical
value of amplification was calculated. Knowing that the amplification is associated with subsurface layers, we used three
different models of overburden: (i) with Quaternary sediments only, (ii) with a complex of Quaternary-Tertiary sediments,
and (iii) with a complex of Quaternary-Tertiary-Triassic sediments and Carboniferous as a basement. Usually, the amplification
of vibrations appears in the Quaternary sediments. However, theoretical calculations of amplification were consistent with
the results obtained from GMPE when a rigid Carboniferous substratum was applied. 相似文献
11.
M. B. Barannik A. N. Danilin B. V. Efimov V. V. Kolobov P. I. Prokopchuk V. N. Selivanov Yu. A. Kopytenko A. A. Zhamaletdinov 《Seismic Instruments》2010,46(3):207-212
The high-voltage rectifier is described developed for the Energy-2 generator, with a capacity of 200 kW in which a step-up
power transformer is used as a converter. The Energy-2 generator is intended for solving problems of precision deep electromagnetic
monitoring of seismoactive regions of the Earth’s crust to find earthquake precursors. Theoretical investigation and numerical
simulation of the high-voltage rectifier are carried out and parameters of its elemental base are optimized. All the high-voltage
rectifier components, heat sink, and forced cooling system were manufactured on the basis of the developed documentation.
The high-voltage rectifier was successfully tested as part of the“Energy-2 generator in August 2009 during the “FENIKS-2009”
experiment. 相似文献
12.
An alternative “direct method” to “mean dynamic topography” (MDT) computations using satellite altimetry-derived “mean sea
surface” (MSS) and “global geopotential model” (GGM), without direct application of the geoid, is devised. The developed approach,
which is based on derivation of an equipotential surface of the gravity field of the Earth that fits to global MSS in least
squares sense, is formulated via a constrained optimization problem. The validity of our method is numerically tested by computing
a global MDT model based on DNSC08 MSS model and EGM2008 GGM as input data. 相似文献
13.
Case histories of water level subsidence in bore-holes as a precursor of earthquakes are given here. Based on the examples,
a testable quantitative theory for causative mechanism of the precursor—“draining-injecting water model with variable discharge”
is proposed (abbreviated to DIW model). Through analysing the constitution law of which the deformation changes in the porous,
water-saturated media under the effect of exterior stress, as first step of all, the authors suggested first a simple “drainage-natural
restoration model” (abbreviated to DNR model), calculated and gave a group of theoretical precursor curve by using DNR model,
compared the theoretical precursor curves of DNR model with the observational curves, found out the differences of the two
curves, studied the causative physical factors that caused the differences then, revised the DNR model, and finally, the theory
on “draining-injecting water model with variable discharge” in the paper was obtained. The authors deduced general equation
of the two dimensions “draining-injecting water linear source drawdown field” in the paper, suggested and developed the concept
on “domain”. DIW model can also give a possible explanation for both regularity and complexity of this precursor. DIW theory
can quantitatively divide the seismogenic process of the foci on the short-term and impending process into several phases,
and by inversing the discharge functionq(τ) curve, the time values by which the phases are divided were obtained. They will be helpful to predicting the occurrence
time of earthquake and judging the DD and IPE model of the seismogenesis.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 194–201, 1993. 相似文献
14.
Luan-Sheng Su 《地震学报(英文版)》1995,8(1):51-56
Based on the observations of many years, it has been found that “small earthquake modulation windows” exist in the situation
of some special geological structures, which respond sensitively to the variations of regional stress fields and the activities
of earthquake swarms greater than moderate strong magnitude, and can supply some precursory information. More than two “small
earthquake modulation windows” can also provide a general orientation of the first main earthquake of a earthquake cluster.
Compared with “seismic window” based on frequency it is no doubt that the “modulation-window” has an unique characteristic
of applicational significance to medium-term earthquake prediction with a time scale of two or three years.
The English version is improved by Prof. Xin-Ling QIN, Institute of Geophysics, SSB, China. 相似文献
15.
研制可合理模拟预测基坑降水过程中引起地面沉降的计算机程序,并提出最优化降水方案。基于三维全耦合数值模型,笔者开发了GWS软件。GWS软件是以比奥固结理论为基础,将土体的非线性特征及土的渗透性随应力状态的动态变化考虑进去,通过耦合地下水渗流场和土体应力场进行模拟预测基坑降水过程中渗流场及地面沉降的变化。以一个实际基坑降水工程为例,经GWS软件计算得出5口井联合抽水方案,后续工程证明此方案正确、可靠。以三维全耦合数值理论为基础的GWS软件,可以为基坑降水工程引起的地下水渗流场变化及地面沉降量提供可靠的预测。 相似文献
16.
Gradient-based similarity in the atmospheric boundary layer 总被引：2，自引：0，他引：2
Zbigniew Sorbjan 《Acta Geophysica》2008,56(1):220-233
The “flux-based” and “gradient-based” similarity in the stable boundary layer and also in the interfacial part of the convective
boundary layer is discussed. The stable case is examined on the basis of data collected during the CASES-99 experiment. Its
interfacial counterpart is considered in both the quasi-steady (mid-day) and non-steady states, utilizing the results of large-eddy
simulations.
In the stable regime, the “gradient-based” approach is not unique and can be based on various master length scales. Three
local master length scales are considered: the local Monin-Obukhov scale, the buoyancy scale, and the Ellison scale. In the
convective “quasi-steady” (mid-day) case, the “mixed layer” scaling is shown to be valid in the mixed layer and invalid in
the interfacial layer. The temperature variance profile in non-steady conditions can be expressed in terms of the convective
temperature scale in the mixed layer. The analogous prediction for velocity variances is not valid under non-steady conditions. 相似文献
17.
Groundwater-flow models depend on hydraulic head and flux observations for evaluation and calibration. A different type of observation—change in storage measured using repeat microgravity—can also be used for parameter estimation by simulating the expected change in gravity from a groundwater model and including the observation misfit in the objective function. The method is demonstrated using new software linked to MODFLOW input and output files and field data from the vicinity of the All American Canal in southeast California, USA. Over a 10-year period following lining of the previously highly permeable canal with concrete, gravity decreased by over 100 μGal (equivalent to about 2.5 m of free-standing water) at some locations as seepage decreased and the remnant groundwater mound dissipated into the aquifer or was removed by groundwater pumping. Simulated gravity from a MODFLOW model closely matched observations, and repeat microgravity data proved useful for constraining both hydraulic conductivity and specific yield estimates. Specific yield estimated using the infinite-horizontal slab approximation agreed well with model-derived values, and the departure from the linear, flat-water-table approximation was small, less than 2%, despite relatively large and dynamic water-table slope. First-order second-moment parameter uncertainty analysis shows reduction in uncertainty for all hydraulic conductivity and specific yield parameter estimates with the addition of repeat microgravity data, as compared to drawdown data alone. 相似文献
18.
赵和云 《地震学报(英文版)》1994,7(3):465-474
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19.
本文利用灰色系统理论GM(1,1)模型研究了地震活跃幕的预测,建立了中国大陆及邻区地震活跃幕的灰色预测模型,通过实例计算证明该模型精密度较高,可以用来预测中国大陆及邻区下一地震活跃幕的大致开始时间以及持续时间。 相似文献
20.
Groundwater is sensitive to the climate change and agricultural activities in arid and semi‐arid areas. Over the past several decades, human activities, such as groundwater extraction for irrigation, have resulted in aquifer overdraft and disrupted the natural equilibrium in these areas. Regional groundwater simulation is important to determine appropriate groundwater management policies, and numerical simulation has become the most popular method. However, most groundwater models were developed with static boundary conditions. In this research, the Minqin oasis, an arid region located in northwest China, was selected as the study area. An artificial neural network (ANN) was developed to simulate effects of weather conditions, agricultural activities and surface water on groundwater level in a dynamic boundary of the domain. Subsequently, a groundwater numerical model, named ANN‐FEFLOW model, was developed, with a dynamic boundary condition defined by the ANN model. The verifying results showed that the model has higher precision, with a root mean square error (RMSE) of 0·71 m, relative error (RE) of 17·96% and R2 of 0·84 relative to the great groundwater change. Furthermore, the groundwater model has higher precision than the conventional groundwater model with static boundary condition, particularly in the area near the dynamic boundary. This study demonstrated that dynamic boundaries can improve the precision of the regional groundwater model in an arid area and that ANN can provide higher accuracy prediction capability for groundwater levels with dynamic boundary. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献