• Title/Summary/Keyword: silty soil

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On the prediction of unconfined compressive strength of silty soil stabilized with bottom ash, jute and steel fibers via artificial intelligence

  • Gullu, Hamza;Fedakar, Halil ibrahim
    • Geomechanics and Engineering
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    • v.12 no.3
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    • pp.441-464
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    • 2017
  • The determination of the mixture parameters of stabilization has become a great concern in geotechnical applications. This paper presents an effort about the application of artificial intelligence (AI) techniques including radial basis neural network (RBNN), multi-layer perceptrons (MLP), generalized regression neural network (GRNN) and adaptive neuro-fuzzy inference system (ANFIS) in order to predict the unconfined compressive strength (UCS) of silty soil stabilized with bottom ash (BA), jute fiber (JF) and steel fiber (SF) under different freeze-thaw cycles (FTC). The dosages of the stabilizers and number of freeze-thaw cycles were employed as input (predictor) variables and the UCS values as output variable. For understanding the dominant parameter of the predictor variables on the UCS of stabilized soil, a sensitivity analysis has also been performed. The performance measures of root mean square error (RMSE), mean absolute error (MAE) and determination coefficient ($R^2$) were used for the evaluations of the prediction accuracy and applicability of the employed models. The results indicate that the predictions due to all AI techniques employed are significantly correlated with the measured UCS ($p{\leq}0.05$). They also perform better predictions than nonlinear regression (NLR) in terms of the performance measures. It is found from the model performances that RBNN approach within AI techniques yields the highest satisfactory results (RMSE = 55.4 kPa, MAE = 45.1 kPa, and $R^2=0.988$). The sensitivity analysis demonstrates that the JF inclusion within the input predictors is the most effective parameter on the UCS responses, followed by FTC.

Effects of Soil Conditioner Treatments on the Changes of Soil Physical Properties and Soybean Yields (토양개량제(土壤改良劑) 처리(處理)가 토양(土壤)의 물리성(物理性)과 대두(大豆) 수량(收量)에 미치는 영향(影響))

  • Jo, In Sang;Hur, Bong Koo;Ryu, Kwan Shig;Um, Ki Tae;Cho, Seong Jin
    • Korean Journal of Soil Science and Fertilizer
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    • v.20 no.1
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    • pp.29-34
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    • 1987
  • This experiment was designed to find out the effects of soil conditioner, Polyacrylamide (PAM) and Bitumen, on the changes of soil aggregate properties and crop yields. The soil conditioners were treated at the rates of 0.5% and 1% to sandy loam and silty clay loam soils. The aggregate stability, wetting angle, mean weight diameter and air permeability were analyzed. Pot experiments were carried out to investigate the soybean growths and soil property changes after the soil conditioners were sprayed to surface soils. Soil aggregate stability was increased remarkably by the soil conditioner, PAM and Bitumen, treatments. PAM was more effective in sandy loam than silty clay loam, but Bitumen was better in silty clay loam. Wetting angle of the soil was changed slightly by PAM treatment, but it was greatly changed to hydrophobic by Bitumen treatment. Air permeability, water infiltration rate and moisture retention of the soils were increased by surface application of soil conditioners, PAM and Bitumen. The growths of soybean in conditioner applicated pots were better than those of untreated pots from early stage, and the yields were increased 6-13%.

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A Field Study on Remediation of Gasoline Contaminated Site by Soil Vapor Extraction (토양증기추출법에 의한 휘발유 오염토양의 현장복원 연구)

  • 김재덕;김영래;황경엽;이성철
    • Journal of Korea Soil Environment Society
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    • v.5 no.1
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    • pp.13-23
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    • 2000
  • The effects of operating condition of soil vapor extraction system and the characteristics of site on the remediation of oil contaminated soil were investigated. Thorough investigation showed that the site was contaminated with gasoline leaked from underground storage tank and the maximum concentration of BTEX and TPH were 1,081 ppm and 5,548 ppm respectively. The leaked gasoline were diffused to 6m deep and the area and volume of the polluted soil were assumed to 170$m^2$ and 1,000$\textrm{m}^3$respectively. The site were consisted of three different vertitical layers, the top reclaimed sandy soil between the earth surface and 3~4m deep, middle silty sand between 3~4m and 6m deep, and the bottom bedrock below the 6m deep. The air pemeability of soil was measured to 1.058-1.077$\times$10$^{-6}$ $\textrm{mm}^2$ by vacuum pump tests. The groundwater which level was 3~4m deep was observed in some areas of this site. The soil vapor extraction system which had 7.5 HP vacuum pump and 8 extraction wells was constructed in this site and operated at 8 hrs/day for 100 days. The BTEX was removed with above 90% efficiency where no groundwater and silty sand were observed. On the contrary, the efficiency of BTEX and TPH were dramatically decreased where groundwater and silty sand were observed. The flow rate of soil air induced by soil vapor extraction system was reduced in deeper soil.

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Mobility of pesticides in different soil textures and gravel contents under soil column (토양 column을 이용한 토성 및 자갈함량별 농약 이동특성)

  • Lee, Sang-Min;Kim, Seong-Soo;Park, Dong-Sik;Hur, Jang-Hyun
    • The Korean Journal of Pesticide Science
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    • v.9 no.4
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    • pp.330-337
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    • 2005
  • This study was investigated to elucidate the pesticide mobility in three different soil textures(Heongseong sandy loam; Chuncheon, loam; Taeback, silty clay loam) and four different gravel contents(0, 20, 40, 60%) of Taebaek soil using soil column. Carbofuran, which ranks the highest water solubility among 7 pesticides(carbendazim, carbofuran, chlorpyrifos, cypermethrin, dimethomorph, diniconazole and endosulfan) was defected over 87% in leachate samples within all soil types from early sampling time. Amount of 5 residual pesticides excluding carbendazim and carbofuran were ordered silty clay loam > loam > sandy loam, indicating pesticide residues are related to percentage of clay contents in soils. Comparing the amount of residual pesticides in soil column(upper, middle and lower layer), 6 pesticides apart from carbofuran were found in the range of $50{\sim}92%$ on the upper layer of silty clay loam and loam. Mobility of pesticides either in soil or leachate samples is dependant on water solubility of pesticide and clay content of soil. The results obtained from four different gravel contents of Tacback soil were similar to the results of three different soil textures. Also it was found that more the gravel contents, faster the flow velocity of leachate water. These results possibly provide an idea to select proper pesticides and to reduce soil and water contamination at alpine and sloped-land.

Shearing Properties of Fiber-Reinforced Soil (섬유혼합 보강토의 전단특성)

  • 조삼덕;김진만
    • Proceedings of the Korean Geotechical Society Conference
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    • 1993.10a
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    • pp.23-28
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    • 1993
  • Shearing properties of soil reinforced with discrete randomly oriented inclusions depend on soil density, particle size, grading, fiber length, tensile strength and stiffness of fiber, mixing ration of fiber, confining stress, etc.. In this paper the effects of those various factors on shear strength of the fiber-reinforced soil was evaluated through triaxial tests and uniaxial tests. Tests were performed on two sandy soils and one silty soil with inclusions in varing lengths, contents and tensile strengths and tested at different confining stresses in triaxial test. From the experimental results, it was investigated if there is an optimal range of fiber lengths and fiber contents for the tested soils.

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A Study on Strength Characteristics of Dredged Soft Clay (준설 연약 점토의 전단강도 특성에 관한 연구)

  • Lee, Song;Yun, Don-Kyu;Paik, Young-Shik
    • Geotechnical Engineering
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    • v.10 no.4
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    • pp.153-166
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    • 1994
  • In this paper, the experimental study on the behavior of the dredged clay was performed by introducing the consolidation teat method using continuous loading. Also a new testing method was examined and the strength of the dredged clay using thin plate was evaluated. The rheological characteristics of the dredged clay are described by the gingham model. The static and rheologic thin plate penetration test is proposed for the shear strength testing method. It is found that both of testing methods are reasonable and have a practicability. Especially, the strength increases for a water content which is less than two times of liquid limit in case of silty soil and clayey soil. About plasticity index, the strength increases rapidly for a value less than 10 for silt, 5 for clay which a water content is normalized by plasticity index of silty soil rather than clayey soil.

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The Coefficients of Variation Characteristic of Stress Distribution in Silty Sand by Probabilistic Load (확률론적 하중에 따른 실트질 모래지반 내 지중응력의 변동계수 특성)

  • Bong, Tae-Ho;Son, Young-Hwan;Kim, Seong-Pil;Heo, Joon
    • Journal of The Korean Society of Agricultural Engineers
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    • v.54 no.6
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    • pp.77-87
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    • 2012
  • Recently, Load and Resistance Factor Design (LRFD) based on reliability analysis has become a global trend for economical and rational design. In order to implement the LRFD, quantification of uncertainty for load and resistance should be done. The reliability of result relies on input variable, and therefore, it is important to obtain exact uncertainty properties of load and resistance. Since soil stress is the main reason causing the settlement or deformation of ground and load on the underground structure, it is essential to clarify the uncertainty of soil stress distribution for accurately predict the uncertainty of load in LRFD. In this study, laboratory model test on silty sand bed under probabilistic load is performed to observe propagation of upper load uncertainty. The results show that the coefficient of variation (COV) of soil stress are varied depending on location due to non-linear relationship between upper load increment and soil pressure increment. In addition, when the load uncertainty is transmitted through ground, COV is decreased by damping effect.

Assessment of p-y Behaviors of a Cyclic Laterally Loaded Pile in Saturated Dense Silty Sand (조밀한 포화 실트질 모래지반에서 횡방향 반복하중을 받는 말뚝의 p-y 거동 평가)

  • Baek, Sung-Ha;Choi, Changho;Cho, Jinwoo;Chung, Choong-Ki
    • Journal of the Korean Geotechnical Society
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    • v.35 no.11
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    • pp.97-110
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    • 2019
  • Piles that support offshore wind turbine structures are dominantly subjected to cyclic lateral loads of wind, waves, and tidal forces. For a successful design, it is imperative to investigate the behavior of the cyclic laterally loaded piles; the p-y curve method, in which the pile and soil are characterized as an elastic beam and nonlinear springs, respectively, has been typically utilized. In this study, model pile tests were performed in a 1 g gravitational field so as to investigate the p-y behaviors of cyclic laterally loaded piles installed in saturated dense silty sand. Test results showed that cyclic lateral loads gradually reduced the overall stiffness of the p-y curves (initial stiffness and ultimate soil reaction). This is because the cyclic lateral loads disturbed the surrounding soil, which led to the decrement of the soil resistance. The decrement effects of the overall stiffness of the p-y curves became more apparent as the magnitude of cyclic lateral load increased and approached the soil surface. From the test results, the cyclic p-y curve was developed using a p-y backbone curve method. Pseudo-static analysis was also performed with the developed cyclic p-y curve, confirming that it was able to properly predict the behaviors of cyclic laterally loaded pile installed in saturated dense silty sand.

Genesis and Classification of the Red-Yellow Podzolic soils derived from Residuum on Acidic and Intermediate Rocks -Vol. 1 (Jeonnam series) (산성암(酸性岩) 및 중성암(中性岩)의 잔적층에 발달(發達)된 적황색토(赤黃色土)의 생성(生成) 및 분류(分類) -제(第) 1 보(報) (전남통(全南統)에 관(關)하여))

  • Um, Ki Tae
    • Korean Journal of Soil Science and Fertilizer
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    • v.4 no.2
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    • pp.187-192
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    • 1971
  • This paper deals mainly with the genesis and classification of the Jeonnam series. These soils have brown to dark brown silt loam and silty clay loam A horizon(strong brown or reddish brown where eroded). Argillic B horizons are dominantly red or yellowish red silty clay loam to silty clay with moderately developed subangular blocky structure and with thin clay cutans on the ped faces. The C horizons are strongly and very deeply weathered strong brown, yellowish brown, pale brown and reddish yellow silty clay loam and sandy loam granitic saprolite. Content of clay increases with depth to a maximum between 100cm. Percolating water seems to be responsible for transportation and oriented deposition of clay. Chemically, soil reaction is strongly acid to medium acid throughout the profile. The content of organic matter is 1 to 2 percent, and decreases regularly with depth. Base saturation is low, based on amount of extractable cations. Characterisltically the Jeonnam series are similar to Red-Yellow Podzolic soils of the United States and are similar to Red-Yellow soils of the Japan. In the writer's opinion the Jeonnam soils are classified as Red Yellow soils. According to USDA 7th approximation, this soil can be classified as Typic Hapludults and in the FAO/UNESCO World Soil Map as Helvic Acrisols.

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Liquefaction Behaviour and Prediction of Deviator Stress for Unsaturated Silty Sand

  • Lee, Dal-Won
    • Journal of The Korean Society of Agricultural Engineers
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    • v.48 no.7
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    • pp.35-43
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    • 2006
  • This study was carried out to investigate the liquefaction behaviour and predict deviator stress with matric suction, of unsaturated silty sand. The unsaturated soil tests were conducted using a modified triaxial cell and specimens were prepared using the moisture tamping method. The axis translation technique was used to create the desired matric suctions in the specimen. Undrained triaxial compression tests were carried out at matric suction of 0, 2, 5, 10 and 25 kPa. The specimens were sheared to axial strains of about 20% to obtain steady state conditions. The results showed that liquefaction of silty sand only occurs at matric suction of 0 kPa and 2 kPa. The results also show that at matric suctions of 5, 10 and 25 kPa, the resistance to liquefaction increases. As the suction increases, the undrained effective stress path approached the drained stress path. Also, the predicted and measured maximum deviator stress for unsaturated soils using the effective stress concept showed good agreement as matric suction increases. The deviator stress increase is nonlinear as matric suction increases.