Research on Prediction of Dam Seepage and Dual Analysis of Lag-Sensitivity of Influencing Factors Based on MIC Optimizing Random Forest Algorithm

Yongtao Liu,Dongjian Zheng,Xin Wu,Xingqiao Chen,Christos T. Georgakis,Jianchun Qiu 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.2

The seepage of the dam is an important representation of the operation characteristics of thedam, and there are many factors affecting the seepage with a certain lag. It is still difficult topredict its change and sensitivity because of complex operating conditions. At present, the lagsensitivityof influence factors of the dam seepage has not been studied. The time seriesinfluence factors of seepage are determined by HTRT (hydrostatic-thermal-rainfall-time)model in this paper. To avoid the pseudo fitting of conventional methods, HTRT model nestedrandom forest algorithm is used to establish the predicting model of the dam seepage. AndMIC algorithm is used to achieve the dual purposes of time lag and sensitivity analysis. Firstly,the time lag of relationship between seepage and its influencing factors is characterized, andthe most appropriate lag time of the HTRT model factors is determined. Secondly, independentcorrelation analysis on all influencing factors is carried out and the sensitivity of each factor isanalyzed by MIC. Meanwhile, the sensitivity of the factors to seepage is quantitatively analyzedby the two parameters of %IncMSE and IncNodePurity of RF algorithm. The sensitivity ofinfluencing factors is analyzed by comparing MIC results with RF results. Combined with thecase, taking the error of fitting prediction as the evaluation index of seepage prediction, theprediction accuracy of MIC-RF model, RF model and MIC-BPNN (Back Propagation neuralnetwork) model is calculated and compared. Case study showed that MIC- RF monitoringmodel has high prediction accuracy, strong adaptability and high robustness in dam seepage,and the sensitivity and time lag of influencing factors can be quantitatively analyzed. Thewater pressure and rainfall of the lag time are 14 days and 16 days respectively. The sensitivitystudy of the time series influencing factors of seepage showed that the water pressurecomponent is the main controlling factor of seepage, and rainfall component is more sensitiveto later stage. The MIC-RF model can be used as a new dam seepage safety monitoringmodel.

하천 보축제체의 배수통문 구조물 측면부 침투 특성

양학영(Hakyoung Yang),김영묵(Youngmuk Kim) 한국지반환경공학회 2020 한국지반환경공학회논문집 Vol.21 No.4

본 연구는 하천 보축제체 내부를 관통하여 설치되는 배수통문 구조물 연결부에서 누수가 발생하는 경우 구조물 측면의 침투 특성을 파악하고 이러한 측면 침투 거동에 따른 파이핑 등이 제체 안정에 미치는 영향을 분석한 수치해석적 연구이다. 측면침투 거동을 고려하기 위해 동일한 모델에 대해 2차원 및 3차원 수치해석을 수행하였다. 그리고 측면 침투의 영향을 분석하고 수치해석의 타당성을 평가하고자 하였다. 연구 결과, 제외지에 수문이 위치한 조건에서 누수가 발생하고 측면 침투를 고려하는 경우 구조물 누수지점 인근의 최대간극수압은 누수가 발생하지 않는 정상적인 침투 상태에 비해 절반 정도로 감소하였다. 특히 측면침투를 고려하지 않는 경우 구조물 하부에서 과도한 간극수압 변화를 보였다. 구조물 상부와 하부의 동수경사는 고수위로 수위가 상승하면서 한계동수경사보다 큰 동수경사를 나타내고 있어 장기간 파이핑에 취약할 것으로 판단된다. 제내지에 수문이 위치하고 측면침투를 고려하지 않는 경우 동수경사와 침투유속 등 침투수의 영향은 측면침투를 고려하는 경우에 비해 과소하게 해석되었다. 수문이 제외지에 위치하고 누수가 발생하여 파이핑 발생 또는 제체 재료 유실이 우려되는 경우 측면 침투를 무시하게 되면 최대 동수경사는 상대적으로 작게 나타났다. 그리고 한계동수경사를 초과하는 기간도 짧은 시간대로 해석되었다. 결과적으로 측면 침투를 무시하게 되면 파이핑 발생 가능성을 과소하게 평가할 수 있어 주의해야 할 것으로 판단된다. This numerical study is to investigate the seepage characteristics of the side of the structure in the event of leakage from the structural connection part of the drainage structure installed through the enlarged levee, and to analyze the effect of piping on the stabilization of the levee by the lateral penetration behavior. To take into account lateral seepage behavior, 2D and 3D numerical analyses were performed on the same model, and the effect of lateral seepage was analyzed to assess the validity of the numerical analysis. As a result, when leakage occurs and a lateral seepage is considered with the gate located on the riverside land, the maximum pore water pressure near the leakage point of the structure has been reduced by half compared to the normal seepage state where no leakage occurred. Excessive variation in the pore pressure was shown at the lower part of the structure, especially if lateral seepage is not considered. As a water level rises to the high water level, it shows the hydraulic gradient was larger than the critical hydraulic gradient, which will be vulnerable to long-term piping. If a gate is located in the inland and side seepage is not considered, the effect of the seepage water such as hydraulic gradient and seepage velocity is underestimated compared with the case of considering side seepage. The maximum hydraulic gradient is relatively small when lateral seepage is neglected if a gate is located in the riverside land and there was might be a risk of piping or loss of material. In addition, the period exceeding the critical hydraulic gradient was interpreted as a short time zone. As a result, it is considered that the possibility of piping can be underestimated if side seepage is ignored.

Experimental Investigation of Joint Filling Materials Performance on Preventing Seepage in Lined Open Concrete Canal (Laboratory and Field Model)

Aqeel Al-adili,Osama Abd Al-ameer,Ammar Al-sharbati 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.5

Seepage is one of the most serious problems of water loss in the irrigation canals. In Iraq, most projects of concrete lining irrigation canals suffer from seepage losses phenomena through joints. The loss of water due to seepage from irrigation canals constitutes a substantial part of the usable water. The aim of this study is to reduce or prevent the seepage by using new alternative joints filling materials. The methodology in this study follows two main categories for calculating and studying the seepage and efficiency of some alternative materials, hoping to apply a new filling joint material, and assessing their performance to prevent seepage. The first category was done by constructing a trapezoidal concrete canal model. The joints filling materials used in this research were : cement-sand mortar, cement-sand mortar with Styrene Butadiene Rubber (SBR), cement-sand with Krystol Internal Membrane (KIM), and Setseal B (liquid polymer with powder). The average percentage of seepage losses was reduced to about 11.3, 29, and 89% when using cement-sand mortar and SBR, cement-sand mortar and KIM, and Setseal B respectively, as joints filling material instead of cement-sand mortar (the initial filling material). While when using Setseal B as a coating material for 9 months duration give no seepage (zero seepage). The second category was carried out by field study, which was done on a branch of irrigation concrete Setseal B as a coating layer was applied on the existing cement-sand joints of the canal (based on the results of the laboratory model tests). It has been tested for 3 weeks. The average reduction percentage in water losses was about 62.5%, by comparing it with using cement-sand mortar only as joints filling material.

Analysis on Slope Stability Considering Seepage Effect on Effective Stress

Yuanzhan Wang,Xufei Liu,Zhikai Zhang,Panbo Yang 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.6

Interaction between seepage field and soil stress field influences soil effective stress in general consideration. In addition, water erosion in soil skeleton can also affect soil effective stress. The current studies conducted triaxial compression experiments with seepage, Duncan-Chang model analysis, ABAQUS numerical simulation and followed by a case study analysis. Experiments show that the water erosion in soil skeleton reduces effective stress strength of soil, which is quantitatively described by the reduction of equivalent confining pressure. Through analyzing the characteristics of soil stress-strain curves, the equivalent confining pressure is applied to improve Duncan-Chang model. Using the modified Duncan-Chang model as well as considering the interaction between seepage field and soil stress field, ABAQUS software package is employed to simulate triaxial compression experiments with seepage. This method is validated by comparing simulation and experimental results. Furthermore, this method is applied in the case study of the overall stability of bank slope under seepage effect and finds that the modified model is more conservative on safety assessment of slope stability. The studies provided evidences to prove the importance of considering soil skeleton eroded by water flow in slope stability analysis quantitatively and proposed a modified Duncan-Chang model for engineering application with consideration of seepage effect.

Seepage Evolution Law and Deformation Failure Characteristics of Porous Media Based on Smoothed Particle Hydrodynamics

Xiong Song,Xiaoqiang Zhang,Shunchuan Wu 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.11

It is difficult to characterize the whole process of seepage movement by traditional numerical methods, which leads to the unclear mechanism of stress-strain change in soil. Therefore, the meshless method smooth particle hydrodynamics method is proposed to study the seepage law and deformation characteristics of soil. Combined with the strain softening model, a nonlinear cohesive force change model of porous media is proposed to accurately describe the evolution characteristics of soil seepage failure. Secondly, the damping coefficient and stress normalization method are used to better eliminate the defects of numerical stress noise generated by soil deformation after boundary interpolation, and improve the accuracy of SPH method in studying the internal stress of soil deformation. It is concluded that the influence of the viscosity coefficient on the unsteady head is significantly higher than that of the constant head. At the same time, the evolution characteristics of soil seepage instability under linear cohesion change are compared and analyzed. It can be seen that the proposed nonlinear cohesion change model is more in line with the actual failure mode of soil seepage. The research results can provide a new method and idea for the study of slope seepage motion range and stability analysis.

Soil attenuation of the seepage potential of metallic elements (Cu, Zn, As(V), Cd, and Pb) at abandoned mine sites: A batch equilibrium sorption and seepage column study

Kim, Juhee,Hyun, Seunghun Elsevier 2017 Journal of hazardous materials Vol.339 No.-

<P><B>Abstract</B></P> <P>Soil attenuation of off-site leaching potential of metallic elements at the two abandoned mine sites was investigated using batch sorption and layered column studies. In batch study, the leachate concentration-specific sorption (<I>K</I> <SUB>d</SUB> <SUP>*</SUP>) by downgradient clean soils was in the order of Pb>Cu>Cd>Zn>As for DY site and Pb>As>Cu>Cd>Zn for BS site. In the layered (mine+clean) soil column, element elution was significantly reduced (e.g., no initial flush, retarded peak arrival, and lower peak concentration) while sulfate elution can be an indicator of the dissolution of sulfur-bearing minerals in mine soils. The greatest reduction was observed for Pb and Cu while the lowest was for Cd (2–19%) and Zn (6–51%), consistent with the batch data. Both the reduced elution at slow seepage and concentration drop after flow interruption support the time-limited propensity. In column segments, the sorptive elements (Cu, Pb, and As) were dominantly found in the inlet while less sorptive ones (Zn and Cd) in the outlet. Both batch and column data suggest that the element leaching with mine leachate movement can be greatly attenuated by the interactions with the surrounding downgradient soil during the seepage process.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Discharge of metals with leachate was greatly reduced by seepage through downgradient soils. </LI> <LI> Leachate acidity was also ameliorated during downward seepage. </LI> <LI> Negligible elution of Pb and Cu was due to their high selectivity on soil matrix. </LI> <LI> Both element release and its retention by clean soils were seepage rate-limited. </LI> <LI> Leachate sulfate levels can be an awareness of off-site mobilization of metallic elements. </LI> </UL> </P>

Dynamic Unloading Instability Mechanism of Underground Cavern Based on Seepage-Damage Coupling

Li-Ping Li,Wenfeng Tu,Zongqing Zhou,Shao-shuai Shi,Mingguang Zhang,Yuxue Chen 대한토목학회 2020 KSCE Journal of Civil Engineering Vol.24 No.5

The seepage-damage coupling effect will aggravate the instability of the surrounding rock during the unloading process of underground cavern excavation. Considering this coupling effect and excavation disturbance, the theoretical solution of the stress state of surrounding rock is derived by using the elastic-brittle damage model. The dynamic criterion of the instability and water inrush is presented. Based on the theoretical derivation, the calculation program for the seepage-damage analysis of the surrounding rock under dynamic unloading is programmed, and the seepage flow and the radius of the damage zone of the surrounding rock are calculated. By analysing the variation of radius of the damaged zone with pore water pressure and excavation radius under different calculation conditions, the influence of dynamic unloading disturbance on the damaged zone of the surrounding rock is discussed. The radius of the damaged zone increases with the pore water pressure and excavation radius. Considering the effect of dynamic unloading, the calculation result of the damaged zone radius and seepage discharge of underground cavern are much larger than the theoretical calculation and coupling calculation of seepage-damage without dynamic unloading. Research methods and results can provide guidance and reference for similar engineering research.

하천제방 직선부 및 만곡부의 침윤선 변화 분석

이승호,강휴택 한국지반공학회 2009 한국지반공학회논문집 Vol.25 No.9

In this study we analyzed the seepage characteristics of meandering section of rivers commonly seen in domestic terrain. The seepage analysis is designed to be more realistic by considering a tangent and meandering section of levee. The levee was idealized to reflect the relevant characteristics by considering the curved angle of 90 degrees and 130 degrees in the spatial frequencies, water elevation conditions, and hydraulic conductivities. Seepage analysis becomes more detailed and precise with the seepage curve shape which is interpreted to indicate the flow of three-dimensional numerical analysis program using VisualFEA. As a result of the analysis, it is shown that the water level in the straight levee was constant, regardless of hydraulic conductivities, and the total head in the meandering section was increased by the overlapping of seepage. Consequently, it is found that the total head was increased more significantly in the case of 90 degrees curved levees than 130 degrees, and the total head showed similar characteristics in the straight levee.

불포화 사질토의 도로함몰 특성에 관한 실험적 연구

권기철 한국도로학회 2018 한국도로학회논문집 Vol.20 No.1

PURPOSES: The purpose of this study is to identify the road-subsidence mechanism in unsaturated sandy soils. METHODS: A series of soil chamber tests were conducted under various conditions. RESULTS: The cavity-expansion characteristics in unsaturated sandy soils due to seepage were affected by the outlet size, seepage intensity, relative density, and fine content. CONCLUSIONS: In unsaturated sandy soils, the cavity-expansion speed was affected by the outlet size, relative density, seepage intensity, and clay content; however, the cavity-expansion shape was very similar. As the outlet size and seepage intensity increased, the cavityexpansion speed increased. As the relative density increased, the cavity-expansion speed increased because of a sudden decrease in shear strength, resulting from the increased saturation (reduction of matric suction). The cavity expanded faster with the increasing clay content, up to a certain threshold. It expanded at a slower rate once it passed the threshold. Finally, it reached a stable state where the cavity did not expand due to seepage.

하천제방의 비정상침투해석을 위한 무차원 설계홍수파형에 관한 연구

전세진,권경준,안원식,Jeon. Se-Jin,Kwon. Kyung-Jun,Ahn. Won-Sik 한국방재학회 2009 한국방재학회논문집 Vol.9 No.4

제방을 설계하거나 기존제방을 보강하기 위해서는 침투해석이 필요하다. 미국, 유럽 등과 같이 대규모하천이 대부분인 외국에서는 댐에서와 같이 정상침투해석을 하고 있으나 우리나라와 일본하천의 경우는 홍수지속시간이 짧아 설계홍수파형을 정상상태로 해석할 경우에는 과대한 외력을 주게되므로 시간에 따른 수위변화를 고려한 비정상 침투해석을 하여야한다. 이 경우 하천수위와 지속시간에 대한 홍수파형이 필요하나 국내에서는 명확한 기준이나 지침이 없다. 본 연구에서는 비정상침투해석에 사용되는 설계홍수파형을 유도하였다. 수위자료가 양호한 낙동강 수계 진동 등 5개 수위관측지점의 과거 주요홍수에 대해 지속시간별 홍수위를 조사하여 무차원화를 시켰다. 그리고 통계적.확률적 처리를 통하여 무차원 설계홍수파형을 작성하였다. 작성된 홍수파형의 적정성은 과거 발생한 원홍수사상과 금회 유도한 설계홍수파형을 이용하여 침투해석을 시행하고 일본의 방법과 비교해서 적정성을 분석하였다. 동수경사법과 한계유속법에서 오차는 각각 진동 <TEX>$0{\sim}0.7%,\;0{\sim}0.7%$</TEX>, 현풍 <TEX>$1.6{\sim}4.0%$</TEX>, <TEX>$1.7{\sim}4.1%$</TEX>, 왜관 <TEX>$0.6{\sim}3.6%$</TEX>, <TEX>$0.6{\sim}3.7%$</TEX>, 낙동 <TEX>$2.0{\sim}8.1%$</TEX>, <TEX>$2.0{\sim}8.1%$</TEX>, 정암 <TEX>$1.2{\sim}9.8%$</TEX>, <TEX>$1.3{\sim}9.9%$</TEX>로 나타났다. 상관성(<TEX>$R^2$</TEX>)은 <TEX>$0.983{\sim}0.999$</TEX> 정도로 매우 상관성이 높게 나타났으며, 일본의 방법보다 합리적이며, 실무에 적용이 가능한 것으로 판단된다. The seepage should be analyzed to design or reinforce the levees. The steady seepage analysis is an usual application in USA and European countries where the large scaled dams and levees are existed. However, Korea and Japan, where the reaching time is short, the excessive forces are applied on the levees at the short reaching time if the seepages are analyzed in steady condition. Accordingly, the unsteady analysis based on the variation of time is necessitated. In the unsteady analysis, the flood wave type is necessary. No criteria and standards, however, are derived for the unsteady seepage in Korea. In the study, the flood wave type is derived for the unsteady seepage. The major reliable flood surface data are collected in 5 stations including Jindong of the Nakdong river basin. The data are sorted in duration, and they are non-dimensionalized. The statistical method is also applied to derive the waves. To verify the study, the seepage is analyzed by the derived wave and applied to the prototype. The results are also compared with the Japanese Method. The errors between the hydraulic gradient and critical velocity method are <TEX>$0{\sim}0.7%$</TEX>, <TEX>$0{\sim}0.7%$</TEX> at the Jindong, <TEX>$1.6{\sim}4.0%$</TEX>, <TEX>$1.7{\sim}4.1%$</TEX> at the Hyunpoong, <TEX>$0.6{\sim}3.6%$</TEX>, <TEX>$0.6{\sim}3.7%$</TEX> at the Waegwan, <TEX>$2.0{\sim}8.1%$</TEX>, <TEX>$2.0{\sim}8.1%$</TEX> at the Nakdong, and <TEX>$1.2{\sim}9.8%$</TEX>, <TEX>$1.3{\sim}9.9%$</TEX> at the Jeongam, respectively. The relationship(<TEX>$R^2$</TEX>) between each method is relatively high as <TEX>$0.983{\sim}0.999$</TEX>. This means the results are more logical than the Japanese method, and the study is applicable to the design of hydraulic structures.