• Title/Summary/Keyword: Modified soil

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Convergent Study on the Preparation of Sludge Modified Soils of Inorganic Consolidation Soil (무기계고화재의 슬러지 개량토 제조에 관한 융합연구)

  • Han, Doo Hee
    • Journal of the Korea Convergence Society
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    • v.8 no.2
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    • pp.157-162
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    • 2017
  • Inorganic stiffening agents were prepared by mixing paper sludge incineration ash, blast furnace slag fine powder quicklime, anhydrous gypsum and fly ash. The main components of the solidifying agent developed for sludge treatment were SiO, $Al_2O_3$, $TiO_2$, $Fe_2O_3$, $Mn_2O_3$, CaO, MgO, $Na_2O$, $K_2O$, $P_2O$, and $SO_3$. Unlike cement, the developed solidifying agent did not contain $Cr^{6+}$, which is known as a carcinogen. Heavy metals and oil contaminated soil were mixed with solidifying agent and cured for 7 days and the heavy metal content was below the environmental standard. Sewage sludge cake, food waste and solidifying agent were mixed with each other, and after 7 days curing, soil component test showed that the heavy metal content was below the environmental standard. After mixing the sludge, solidifying agent and additive mixture into the beaker, the ammonia concentration was measured to be 0 after 3 days.

Three-Dimensional Finite Element Analysis of Tieback Walls in Sand

  • Lim, Yu-Jin;Briaud, Jean-Louis
    • Geotechnical Engineering
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    • v.13 no.3
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    • pp.33-52
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    • 1997
  • A three dimensional nonlinear finite element analysis is used to study the influence of various design decisions for tieback walls. The numerical model simulates the soldier piles and the tendon bonded length of the anchors with beam elements, the unbonded tendon with a spring element, the wood lagging with the shell elements, and the soil with solid 3D nonlinear elements. The soil model used is a modified hyperbolic model with unloading hysteresis. The complete sequence of construction is simulated including the excavation, and the placement and stressing of the anchors. The numerical model is calibrated against a full scale instrumented tieback wall at the National Geotechnical Experimentation Site (NGES) on the Riverside Campus of Texas A&M University. Then a parametric study is conducted. The results give information on the influence of the following factors on the wall behavior : location of the first anchor, length of the tendon unbonded zone, magnitude of the anchor forces, embedment of the soldier piles, stiffness of the wood lagging, and of the piles. The implications in design are discussed.

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Cyclic Hardening and Degradation Effects on Site Response during an Earthquake (지진시 지반의 반복경화/연화 현상에 의한 부지응답 특성 영향 연구)

  • Lee, Jin-Sun
    • Journal of the Earthquake Engineering Society of Korea
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    • v.12 no.6
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    • pp.65-71
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    • 2008
  • A one-dimensional site response analysis program (KODSAP) was developed using cyclic soil behavior model by using the modified parallel IWAN model. The model is able to predict the cyclic hardening and degradation of soil through the adjustment of the internal slip stresses of its elements beyond the cyclic threshold, and satisfies Bauschinger's effect and the Masing rule in terms of its own behavior characteristics. The program (KODSAP) used the direct integration method in the time domain. The elasticity of the base rock was considered as a viscous damper boundary condition. The effects of cyclic hardening or degradation of soil on site response analysis were evaluated through parametric studies. Three types of analyses were performed to compare the effect of analysis and cyclic parameter on site response. The first type was equivalent linear analysis, the second was nonlinear analysis, and a third was nonlinear analysis using the cyclic hardening or degradation model.

Cap Model을 이용한 기초식반의 수동해석(I) -범용프로그램의 검증과 수치계산례-

  • 박병기;정진섭
    • Geotechnical Engineering
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    • v.3 no.2
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    • pp.29-40
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    • 1987
  • This paper aims at investigating the characteristics of soil deformation by finite element method (FEM) coupling the cap model with the multi.purpose program developed by authors for the analysis of foundation displacement. The cap model as the constitutive equation has proved to be very useful to a partially saturated roils as well as rocks with high accuracy. As described in the Previous Paper (Park et al 1987) , there exist some difficulties in the determination of soil parameters in order to use the cap model at Present. However the authors have been studying to seek the method for the determination of the soil parameters from the laboratory results of conventional cylindrical triaxial test. Though the computer program advocated by foreign scholars has been kept secret, authors accomplished in performing the FEM analysis by the algorithm and program developed by authors for the cap model. Good results are obtained compared with those published already by Desai(1981) The main conclusions analyzed are as follows: 1. The cap model can be coupled with the multi.purpose computer program of authors bases on the Biot's consolidation theory without loss of generality. 2. Big difference appears in the settlement of center of the embankment between the cap modes and the modified Cam clay model in undrained conditions. The more study on which is more accurate should be performed in this respect.

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A Study on the Estimation Method of Loss Ratio in Dredged Fills (준설매립토의 유실율 평가방법 정립에 관한 연구)

  • Kim, Seog-Yeol;Choi, Hyo-Pum;Park, Jae-Eock;Kim, Seung-Wook
    • Journal of the Korean GEO-environmental Society
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    • v.3 no.1
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    • pp.67-77
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    • 2002
  • Volume change of the dredged soils is composed of the volume loss of soil particle flowing over an outflow weir with water and settlement due to both the self-weight consolidation in reclaimed layer and the desiccation at the surface of reclaimed layer. In order to estimate the amount of soil particles flowing over an outflow weir with water, the evaluation procedure of loss ratio of the dredged soils is proposed in the present study based on the Marsal's modified breakage theory and the results of hydrometer analyses. To verify a validity of the proposed procedure, evaluated loss ratio is compared with results from the other existing methods. The model test results and those of field test were compared and analyzed. Also, the variation of soil loss ratio was examined through the model test in the lab.

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The Isolation of Keratinophilic Fungi from Soils in Chon-ju Area (전주근교의 토양에서 분리된 호각화질성 진균의 오염에 관한 조사)

  • Her In;Lee Joo-Muk;Yoon Chang-Mo
    • Journal of Veterinary Clinics
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    • v.7 no.2
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    • pp.489-495
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    • 1990
  • The purpose of this study was to investigate the contamination rates of Keratinophilic fungi in soils In Chonju. From september to November 1986, 98 soil samples were collected at the school and children's play ground, dog barn, pig barn, cow barn, horse barn and fowl barn( total 33 sites ). The samples were collected at the different depths(0~2cm, 30cm, 50cm ) in each of the sites, respectively. Each sample was cultured at 25$^{\circ}C$ according to Modified hair baiting method by using horse mane hair as a bait. The results obtained were summerized as follows ; 1. Eighty one of the 98 soil samples were found to be positive for Keratinophilic fungi. 2. In the examination of keratinophilic fungi in 98 soil samples, the organisms isolated weie as follows; Microsporum gypseum 20, Trichophyton ajelloi 15, Chrysosporium tropicum 40, C. Keratinophilum 24, C. tuberculatum 6 and Chrysosporium spp. like organism 4 strains. 3. The positive rates of keratinophilic fungi in each of the depths were 87.9%(29/33) in surface layer, 90.9%(30/33) in middle layer and 68.8%(22/32) in deep layer. 4. The positive rates of Keratinophilic fungi in each of the sites were 100%(3/3) in horse barn 91.7% (l1/12) in dog barn, 88.9%(16/18) in pig barn, 86.7%(13/15) in cow barn, 76.2%(16/21) in fowl barn and 75.9%(22/29) in school and children's play ground. 5. The isolation rates of M. gypseum, Pathogenic fungi for human and animals, were as follows ; 58.3% in dog barn(surface layers 100%, middle layers 50%, deep layers 25%) and 16.7% in pig barn(surface 33.3%, middle 16.7%, deep 0%). In the cow barn, the isolation rates were 13.3%(surface 40.0%, middle 0%, deep 0%) and 10% in horse barn(surface l00%, middle 100%, depp 100%). In the fowl barn, the isolation rates was 19.1%(surface 28.8%, middle 14.3%, deep 14.3%) and 3.5% in school and children's play ground(surface 0%, middle 0%, deep 11.1%).

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A Study on Rapid Residual Analysis of Benzo(a)pyrene in Agricultural Products and Soils (농산물 및 경작지 토양 시료 중 Benzo(a)pyrene 신속잔류분석법 개선 연구)

  • Kim, Hee-Gon;Ham, Hun-Ju;Hong, Kyong-Suk;Shin, Hee-Chang;Hur, Jang Hyun
    • Korean Journal of Environmental Agriculture
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    • v.39 no.1
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    • pp.44-49
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    • 2020
  • BACKGROUND: Benzo(a)pyrene is a highly toxic substance which has been listed as a Group I carcinogen by the International Agency for Research on Cancer. There have been numerous studies by researchers worldwide on benzo(a)pyrene. Soxhlet, ultrasound-assisted, and liquid-liquid extractions have been widely used for the analysis of benzo(a)pyrene. However these extraction methods have significant drawbacks, such as long extraction time and large amount of solvent usage. To overcome these disadvantages, we aimed to establish a rapid residual analysis of benzo(a)pyrene content in agricultural products and soil samples. METHODS AND RESULTS: A Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method was used as the pretreatment procedure. For rapid residual analysis of benzo(a)pyrene, a modified QuEChERS method were used, and the best codition was demonstrated after various performing instrument analysis. The extraction efficiency of this method was also compared with Soxhlet extraction, the current benzo(a)pyrene extracting method. Although both methods showed high recovery rates, the rapid residual analysis method markedly reduced both the measurement time and solvent usage by approximately 97% and 96%, respectively. CONCLUSION: Based on these results, we suggest the rapid residual analysis method established through this study, faster and more efficient analysis of residual benzo(a)pyrene in major agricultural products such as rice, green and red chili peppers and also soil samples.

Infiltration Analysis for Surficial Stability Evaluation of Two-layered Slopes (2층 지반의 표면파괴에 대한 안정성 평가를 위한 침투거동 해석)

  • Cho Sung-Eun
    • Journal of the Korean Geotechnical Society
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    • v.21 no.8
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    • pp.45-53
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    • 2005
  • Shallow slope failures in residual soil during periods of prolonged infiltration are common over the world. Therefore, this study examines an approximate method to estimate the influence of infiltration on surficial stability of slopes by one-dimensional infiltration model. Modified GAML model based on the Green-Ampt model was extended to predict the infiltration behavior of two-layered slope. Then, the model has been considered to evaluate the likelihood of shallow slope failure which is induced by a particular rainfall event that accounts for the rainfall intensity and duration for various return periods in two-layered soil profile. The results obtained from the approximate method were compared with those obtained from numerical analyses. According to the results, with the use of properly estimated input parameters, the proposed method was found to give good results that agree reasonably well to those of the more rigorous finite element analyses.

An Assessment of a Resilient Modulus Model by Comparing Predicted and Measured Elastic Deformation of Railway Trackbeds (철도노반의 탄성변위 예측 및 측정을 통한 회복탄성계수 모델 평가)

  • Park, Chul-Soo;Kim, Eun-Jung;Oh, Sang-Hoon;Kim, Hak-Sung;Mok, Young-Jin
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.10a
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    • pp.1404-1414
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    • 2008
  • In the mechanistic-empirical trackbed design of railways, the resilient modulus is the key input parameter. This study focused on the resilient modulus prediction model, which is the functions of mean effective principal stress and axial strain, for three types of railroad trackbed materials such as crushed stone, weathered soil, and crushed-rock soil mixture. The model is composed with the maximum Young's modulus and nonlinear values for higher strain in parallel with dynamic shear modulus. The maximum values is modeled by model parameters, $A_E$ and the power of mean effective principal stress, $n_E$. The nonlinear portion is represented by modified hyperbolic model, with the model parameters of reference strain, ${\varepsilon}_r$ and curvature coefficient, a. To assess the performance of the prediction models proposed herein, the elastic response of a test trackbed near PyeongTaek, Korea was evaluated using a 3-D nonlinear elastic computer program (GEOTRACK) and compared with measured elastic vertical displacement during the passages of freight and passenger trains. The material types of sub-ballasts are crushed stone and weathered granite soil, respectively. The calculated vertical displacements within the sub-ballasts are within the order of 0.6mm, and agree well with measured values with the reasonable margin. The prediction models are thus concluded to work properly in the preliminary investigation.

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The Influence of Net Normal Stresses on the Shear Strength of Unsaturated Residual Granite Soils (화강풍화잔적토의 불포화전단강도에 미치는 순연직응력의 영향)

  • 성상규;이인모
    • Journal of the Korean Geotechnical Society
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    • v.19 no.2
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    • pp.27-38
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    • 2003
  • The characteristics and prediction model of the shear strength of unsaturated residual granite soils were studied in this paper. In order to investigate the influence of the net normal stress on the shear strength, unsaturated triaxial tests and SWCC tests were carried out by varying the net normal stress. Experimental data for unsaturated shear strength tests were compared with predicted shear strength envelopes obtained from existing prediction models. It was shown that the soil-water characteristic curve and the shear strength of the unsaturated soil varied with the change of the net normal stress. Therefore, to achieve a truly descriptive shear strength envelope for unsaturated soils, the effect of the normal stress on the contribution of matric suction to the shear strength has to be taken into consideration. In this paper, a modified prediction model f3r the unsaturated shear strength was proposed.