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Effect of Spatial Variability in the Geometry of Fractures on Granite Slope Stability

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Journal of Earth Science 2023年

作者： Lin Jia Jing-Sen Cai Li Wu tian-chyi jim yeh E-Chuan Yan Yi Du Faculty of Engineering China University of Geosciences Engineering Research Center of Rock-Soil Drilling & Excavation and Protection Ministry of Education China University of Geosciences tianjin Key Laboratory of Water Resources and Environment Tianjin Normal University Department of Hydrology and Atmospheric Sciences University of Arizona

A DFN-DEC(discrete fracture network-distinct element code) method based on MATLAB platform is developed to generate heterogeneous DFN. Subsequently, the effects of the spatial variability(the mean μ and the standard deviation σ) of the geometric properties(i.e., the fracture dip D,the trace length T and the spacing S) of both the gently-dipping(denoted with 1) and the steeply-dipping(denoted with 2) fractures on the stability of granite slope are investigated. Results indicate that the proposed DFN-DEC method is robust, generating fracture networks resemble the reality. In addition, the spatial variability of fracture geometry, influencing the structure of granite slope, plays a significant role in slope stability. The mean stability of the slope decreases with the increase of μD1, σD2, μT1,μT2, σT1, σT2, and the decrease of σD1, μD2, μS1 and μS2. Among them, μT1, μD1 and μS1 have the major *** the fracture spacing is large, the variability in the fracture geometry becomes less relevant to slope stability. When within some ranges of the fracture spacing, the spatial varying of dips can increase the slope stability by forming an interlaced structure. The results also show that the effects of the variability of trace length on slope stability depend on the variability of dip. These findings highlight the importance of spatial variability in the geometry of fractures to rock slope stability analysis.

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Hydraulic tomography to characterize ,heterogeneity of unconfined aquifers

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南京大学学报（自然科学版） 2011年第3期47卷 252-264页

作者： Zhu Jun-Feng tian-chyi jim yeh Mao De-Qiang Kentucky Geological Survey University of Kentucky Lexington KY USA Department of Hydrology and Water Resources University of Arizona Tucson AZ USA

Analytical models are the most widely used tools for analyzing pumping tests in unconfined *** water flow induced by a pumping test in an unconfined aquifer is highly nonlinear near the water *** analytical models are inadequate to describe the nonlinear flow due to their simplified representations of the drainage process and drawdowns at the water ***,these models assume aquifer homogeneity while real aquifers are inherently *** emerged hydraulic tomography(HT)is a cost-effective method for mapping spatial distribution of aquifer hydraulic *** takes advantage of the power of numerical models and fuses information from multiple cross-hole tests conducted at different locations to image aquifer properties in greater *** this study,we extend the HT concept to unconfined *** accurately describe the groundwater flow due to a HT survey in an unconfined aquifer,a fully three dimensional variably saturated flow model based on mixed form of the Richards equation is *** responses in both saturated and unsaturated zones are used to estimate spatial variations of hydraulic conductivity,specific storage,and a soil water constitutive model parameter through a successive linear estimator.A sensitivity analysis is performed to investigate the relation between pressures and different *** HT method for unconfined aquifers is then tested in a synthetic three dimensional field scale *** test shows that the proposed HT method can effectively map spatial variations of hydraulic parameters in an unconfined *** characterizing hydraulic conductivity in both saturated and unsaturated regimes is possible,characterization of specific storage is limited in the saturated flow regime and characterization of the soil water constitutive model parameter is limited in the unsaturated flow *** other limitations of HT for unconfined aquifers and potential improvements are also discu

关键词：英文摘要内容介绍编辑工作期刊

Exploiting Electrical Resistivity Tomography for Hydraulic Tomography: Sandbox Experiments

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Exploiting Electrical Resistivity Tomography for Hydraulic T...

Comparison of smoothness-constrained and geostatistically based cross-borehole electrical resistivity tomography for characterization of solute tracer plumes

2020年中国地球科学联合学术年会

作者： Dong Xu Xiangyun Hu Ronglin Sun tian-chyi jim yeh China University of Geosciences The University of Arizona

The increasing interest in the accurate predictions of groundwater flow and solute transport in the subsurface has prompted a large number of studies on the high-resolution characterization of subsurface heterogeneity. Although hydraulic tomography (HT) has been proven as an effective technique to characterize hydraulic heterogeneity of aquifers, prior site-specific geologic structures from electrical resistivity tomography (ERT) could play an important role when the number of pumping tests and drawdown measurements is sparse. This study proposes an approach that exploits the merits of ERT and HT to improve the estimation of K using a sparse HT network. To test this approach,

关键词： ERT Exploiting Electrical Resistivity Tomography for Hydraulic Tomography Sandbox Experiments

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Water Science and Engineering 2016年第4期9卷 274-286页

作者： Andreas Englert Andreas Kemna Jun-feng Zhu Jan Vanderborght Harry Vereecken tian-chyi J.yeh Institute of Geology Mineralogy and GeophysicsRuhr University Bochum Department of Geophysics Steinmann InstituteUniversity of Bonn Kentucky Geological Survey University of Kentucky Agrosphere Institute for Bio- and Geosciences(IBG-3)Forschungszentrum Jlich GmbH Department of Resources Engineering National Cheng Kung University Department of Hydrology and Water Resources The University of Arizona

Experiments using electrical resistivity tomography(ERT) have shown promising results in reducing the uncertainty of solute plume characteristics related to estimates based on the analysis of local point measurements *** explore the similarities and differences between two cross-borehole ERT inversion approaches for characterizing salt tracer plumes,namely the classical smoothness-constrained inversion and a geostatistically based approach,we performed two-dimensional synthetic *** assumptions about the solute transport model and the electrical forward and inverse model allowed us to study the sensitivity of the ERT inversion approaches towards a variety of basic conditions,including the number of boreholes,measurement schemes,contrast between the plume and background electrical conductivity,use of a priori knowledge,and point *** results show that geostatistically based and smoothness-constrained inversions of electrical resistance data yield plume characteristics of similar quality,which can be further improved when point measurements are incorporated and advantageous measurement schemes are *** expected,an increased number of boreholes included in the ERT measurement layout can highly improve the quality of inferred plume characteristics,while in this case the benefits of point conditioning and advantageous measurement schemes *** ERT inversion approaches are similarly sensitive to the noise level of the data and the contrast between the solute plume and background electrical conductivity,and robust with regard to biased input parameters,such as mean concentration,variance,and correlation length of the *** sophisticated inversion schemes have recently become available,in which flow and transport as well as electrical forward models are coupled,these schemes effectively rely on a relatively simple geometrical parameterization of the hydrogeological ***,we believe that standard uncoupled ER

关键词： Electrical resistivity tomography Inversion technique Solute tracer plume Synthetic experiment Plume characteristics

Uniqueness, scale, and resolution issues in groundwater model parameter identification

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Water Science and Engineering 2015年第3期8卷 175-194页

作者： tian-chyi J.yeh De-qiang Mao Yuan-yuan Zha Jet-chau Wen Li Wan Kuo-chin Hsu Cheng-haw Lee Department of Hydrology and Water Resources The University of Arizona Department of Resources Engineering National Cheng Kung University Department of Geophysics Colorado School of Mines State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University Department of Safety Health and Environmental Engineering National Yunlin University of Science and Technology Research Center for Soil & Water Resources and Natural Disaster Prevention National Yunlin University of Science and Technology

This paper first visits uniqueness, scale, and resolution issues in groundwater flow forward modeling problems. It then makes the point that non-unique solutions to groundwater flow inverse problems arise from a lack of information necessary to make the problems well defined. Subsequently, it presents the necessary conditions for a well-defined inverse problem. They are full specifications of （1） flux boundaries and sources/sinks, and （2） heads everywhere in the domain at at least three times （one of which is t = 0）, with head change everywhere at those times being nonzero for transient flow. Numerical experiments are presented to corroborate the fact that, once the necessary conditions are met, the inverse problem has a unique solution. We also demonstrate that measurement noise, instability, and sensitivity are issues related to solution techniques rather than the inverse problems themselves. In addition, we show that a mathematically well-defined inverse problem, based on an equivalent homogeneous or a layered conceptual model, may yield physically incorrect and scenario-dependent parameter values. These issues are attributed to inconsistency between the scale of the head observed and that implied by these models. Such issues can be reduced only if a sufficiently large number of observation wells are used in the equivalent homogeneous domain or each layer. With a large number of wells, we then show that increase in parameterization can lead to a higher-resolution depiction of heterogeneity if an appropriate inverse methodology is used. Furthermore, we illustrate that, using the same number of wells, a highly parameterized model in conjunction with hydraulic tomography can yield better characterization of the aquifer and minimize the scale and scenario-dependent problems. Lastly, benefits of the highly parameterized model and hydraulic tomography are tested according to their ability to improve predictions of aquifer responses induced by independent stresses not u

关键词： Uniqueness Scale Resolution Forward and inverse problems Hydraulic tomography

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运用水力层析法对含水层裂隙带成像

水文地质工程地质 2008年第6期35卷 6-11页

作者：郝永红叶天齐韩宝平项建维朱峰倪春发天津师范大学水环境与水资源重点实验室天津300387 Department of Hydrology and Water Resources The University of Arizona 徐州师范大学徐州221116

含水层裂隙带的识别,是准确模拟计算地下水流和污染扩散的前提。本研究通过数值实验,运用近年来发展起来的水力地质层析方法,对含水层裂隙带成像。文章设定一个17m×17m的二维垂直饱和裂隙含水层,含水层有2口斜井。在斜井与裂隙带的交... 详细信息

含水层裂隙带的识别,是准确模拟计算地下水流和污染扩散的前提。本研究通过数值实验,运用近年来发展起来的水力地质层析方法,对含水层裂隙带成像。文章设定一个17m×17m的二维垂直饱和裂隙含水层,含水层有2口斜井。在斜井与裂隙带的交叉点分别进行抽水试验,由感应器收集水位响应数据,运用VSAFT2对裂隙带进行识别。数值实验证明,水力层析法结合地下水流的逆算方法——连续线性算法(SSLE),可以比较准确地识别非均质含水层的参数分布;非稳定流条件下的识别结果好于稳定流的结果;信息齐全条件下的结果好于资料缺乏时的结果。

关键词：水力层析法裂隙成像含水层抽水试验地质统计