Performance of under foundation shock mat in reduction of railway-induced vibrations

Javad Sadeghi,Ehsan Haghighi,Morteza Esmaeili 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.78 No.4

Under foundation shock mats have been used in the current practice in order to reduce/damp vibrations received by buildings through the surrounding environment. Although some investigations have been made on under foundation shock mats performance, their effectiveness in the reduction of railway induced-vibrations has not been fully studied, particularly with the consideration of underneath soil media. In this regard, this research is aimed at investigating performance of shock mat used beneath building foundation for reduction of railway induced-vibrations, taking into account soil-structure interaction. For this purpose, a 2D finite/infinite element model of a building and its surrounding soil media was developed. It includes an elastic soil media, a railway embankment, a shock mat, and the building. The model results were validated using an analytical solution reported in the literature. The performance of shock mats was examined by an extensive parametric analysis on the soil type, bedding modulus of shock mat and dominant excitation frequency. The results obtained indicated that although the shock mat can substantially reduce the building vibrations, its performance is significantly influenced by its underneath soil media. The softer the soil, the lower the shock mat efficiency. Also, as the train excitation frequency increases, a better performance of shock-mats is observed. A simplified model/method was developed for prediction of shock mat effectiveness in reduction of railway-induced vibrations, making use of the results obtained.

라돈 가스 실내 유입 차단 소재 및 시스템 개발과 검증

김동진,이철민,이혜원 한국냄새환경학회 2022 실내환경 및 냄새 학회지 Vol.21 No.2

This study installed and evaluated the efficiency of a radon barrier membrane, radon mat, and radon well in the removal and reduction of radon gas that originates from the soil and flows indoors. The study aims to present a fundamental and long-term solution to radon reduction in buildings by preventing soil radon, which is the main source of radon gas, from migrating indoors. A radon barrier membrane, radon mat, and radon well were developed and verified, and the radon reduction effect of each system was evaluated. Through applying a special radon gas blocking film with a 5-layer structure, the radon barrier membrane prevents radon gas particles from passing through the polymer deposited on the radon blocking film. The radon mat is a type of radon reduction construction method that induces radon gas generated from the soil under the building to move in the desired direction through the plate-structured pressure reducing panel and discharges radon gas to the outside of the building through an exhaust pipe and fan installed at the edge. In addition, the radon well can also be applied to special structures such as old buildings and historical sites where it is difficult to directly reduce radon concentration within the building foundation, because the intake area can be controlled and, therefore, the method can be applied in a variety of environments and ranges. In the case of Intervention 1 (installing a radon barrier membrane and radon mat), the soil radon was reduced by 24.7%. Intervention 2 (installing a radon barrier membrane, radon mat, and radon well) reduced the soil radon by 45.1%, indicating that the effect of reducing the soil radon concentration was 1.8 times higher compared with installing only the radon barrier membrane and radon mat. The measurement showed that the indoor radon concentration was reduced by 46.5%, following the reduction in soil radon concentration through Interventions 1 and 2, demonstrating the effect of reducing indoor radon gas by installing the radon barrier membrane, radon mat, and radon well. Through the production and installation of prototype systems, this study confirmed the reduction effect of radon concentration in soil and indoor air. These systems achieved a higher efficiency at a relatively low cost than that achieved with the existing radon reduction methods applied in Korea and abroad. .

SWAT 모형을 이용한 볏짚매트의 토양유실 저감효과 분석

장원석,박윤식,최중대,김종건,신민환,류지철,강현우,임경재,Jang, Won-Seok,Park, Youn-Shik,Choi, Joong-Dae,Kim, Jong-Gun,Shin, Min-Hwan,Ryu, Ji-Chul,Kang, Hyun-Woo,Lim, Kyoung-Jae 한국농공학회 2010 한국농공학회논문집 Vol.52 No.3

The purpose of this study is to evaluate sediment yield reduction under various field slope conditions with rice straw mat. The Vegetative Filter Strip Model-W (VFSMOD-W) and Soil and Water Assessment Tool (SWAT) were used for simulation of sediment yield reduction effect of rice straw mat. The Universe Soil Loss Equation Practice factor (USLE P factor), being able to reflect simulation of rice straw mat in the agricultural field, were estimated for each slope with VFSMOD-W and measured soil erosion values under 5, 10, and 20 % slopes. Then with the regression equation for slopes, USLE P factor was derived and used as input data for each Hydrological Response Unit (HRU) in the SWAT model. The SWAT Spatially Distributed-HRU (SD-HRU) pre-processor module was utilized, moreover, in order to consider spatial location and topographic features (measured topographic features by field survey) of all HRU within each subwatershed in the study watershed. Result of monthly sediment yield without rice straw mat (Jan. 2000 - Aug. 2007) was 814.72 ton/month, and with rice straw mat (Jan. 2000 - Aug. 2007) was 526.75 ton/month, which was reduced as 35.35 % compared without it. Also, during the rainy season (from Jun. to Sep. 2000 - 2007), when without vs. with rice straw mat, monthly sediment indicated 2,109.54 ton and 1,358.61 ton respectively. It showed about 35.60 % was reduced depending on rice straw mat. As shown in this study, if rice straw mat is used as a Best Management Practice (BMP) in the sloping fields, rainfall-driven sediment yield will be reduced effectively.

Protective role of mats in maintaining soil integrity on temporary forest roads: An in-depth analysis of their application

Ol’ga Kunickaya,Novgorodov Dulus,Druzyanova Varvara,Levushkin Dmitry,Tikhonov Evgeniy,Perfiliev Pavel,Kleveko Vladimir 한국산림과학회 2024 Forest Science And Technology Vol.20 No.2

Forest resources have paramount importance for countries around the world. Among these resources, forest soils bear the brunt of the negative impact resulting from logging, especially during the transportation of wood. In this regard, the construction of temporary forest roads using soil-protective materials can become mandatory. This study involved the immediate application of shrubs and plastic mats to previously untreated trails. The study found that these methods have a less negative effect on the soil bulk density: 10.2-43.6% for shrub mats and 3.4-38.5% for plastic mats compared to the baseline values. At the same time, the density increased by 8.5-64.1% in the control area. The content of moisture and organic matter changed relative to the initial values by -14.1-0.6% and 0.1-5.2% for shrub mats. The differences were -5.2-0.0% (moisture) and -1.3-0.0% (organic matter) for plastic mats. These results demonstrated that the use of plastic mats to protect the soil from the adverse effects of logging equipment is becoming a very promising and effective strategy. This study highlights the importance of these soil protection measures to maintain the health and viability of forest ecosystems during logging.

토양 손실 평가에 의한 식생매트의 허용 소류력 결정

이두한(Lee, Du-Han),이동섭(Rhee, Dong Sop),김명환(Kim, Myounghwan) 한국산학기술학회 2013 한국산학기술학회논문지 Vol.14 No.11

친환경 하천사업의 활성화로 식생매트의 사용은 증가하고 있으나 수리적 안정성에 대한 평가기법은 제시되 지 않은 실정이다. 본 연구는 호안용 식생매트 제품의 객관적인 수리안정성 시험 기법 개발을 위해 수행하였다. 이를 위해서 식생매트 2종에 대한 실규모 실험을 수행하여 수리량을 측정하고 분석하여 작용 소류력을 계산하였다. 작용 소류력에 대한 토양손실평가를 위하여 지상라이다에 의한 측량을 수행하고 실험 전후의 하상고 변화를 평가하여 토 양손실지수(CSLI)를 산정하였으며, 작용 소류력과 함께 도시하여 허용 소류력을 정량적으로 평가하였다. 하상고에 대 한 정밀 측량 결과 분석에 의해서 식생매트가 안정한 경우에는 하상 변동이 국부적으로 제한되나, 불안정으로 판정되 는 경우에는 식생매트 하부에서 비교적 큰 규모의 하상 변동이 발생하며 이는 자연 하상의 거동과 유사함을 확인하 였다. 이상의 연구를 통해서 ASTM D 6040에 의한 식생매트의 허용 소류력 평가가 파괴 메카니즘 및 토양손실판정 기준에서 유효함을 확인할 수 있었다. By the activation of environment-friendly river works, application of vegetation mats is increasing, however, evaluation techniques for hydraulic stability of vegetation mats are not presented. This study is conducted to develop the objective test method for vegetation mats. Two kind of vegetation mats are tested by the real scale experiments, and hydraulic quantities are measured and analyzed to evaluate acting shear stresses. To evaluate soil loss, Terrestrial 3D LiDAR measurement is conducted and soil loss index are calculated from changes of bed elevation. Quantified evaluation for permissible shear stresses is conducted by graphical method for acting shear stresses and soil loss index. By the results of precision survey, changes of sub soil are limited to local range in stable cases and relatively large changes of sub soil which is similar to natural river bed are detected in unstable cases. From the study, evaluation of permissible shear stresses by ASTM D 6040 is avaliable in the failure mechanism and failure criteria by soil loss index.

연약한 준설점토상 매립시 포설된 PET 매트와 지반거동에 관한 연구

이만수,양태선,지성현 한국지반공학회 2006 한국지반공학회논문집 Vol.22 No.3

Geosynthetic damage has attracted a major attention since the introduction of geotextiles for civil engineering applications. In this study 3 pilot trial embankments were carried out to investigate the behaviours of reinforced embankments over soft cohesive soils and to find the optimum methodology of embankments over soft soils. As the seamed part of polyester mat (PET, tensile strength 15 ton) used in the first full-scale field test was ruptured under progressing rotational slope failure because of unexpectedly rapid construction of embankments, the excessive pore water pressures were measured. On the soil behavior where tension explosion of mat was continued, pore pressure larger than the one caused by embankment height was measured. Especially, at the depth of 5.0 m under the ground pore pressure increased over long term. It was discussed with respect to the height of embankment and heaving behavior of soft soils.

Evaluation of the influence of interface elements for structure - isolated footing - soil interaction analysis

Rajashekhar Swamy, H.M.,Krishnamoorthy, A.,Prabakhara, D.L.,Bhavikatti, S.S. Techno-Press 2011 Interaction and multiscale mechanics Vol.4 No.1

In this study, two extreme cases of compatibility of the horizontal displacements between the foundation and soil are considered, for which the pressure and settlements of the isolated footings and member end actions in structural elements are obtained using the three dimensional models and numerical experiments. The first case considered is complete slip between foundation and soil, termed as the un-coupled analysis. In the second case of analysis, termed as the coupled analysis, complete welding is assumed of joints between the foundation and soil elements. The model and the corresponding computer program developed simulate these two extreme states of compatibility giving insight into the variation of horizontal displacements and horizontal stresses and their intricacies, for evaluation of the influence of using the interface elements in soil-structure interaction analysis of three dimensional multiscale structures supported by isolated footings.

옥상녹화용 식생매트에 적합한 토양과 토심 선정

이은희 ( Eun Heui Lee ),강규이 ( Kyu Yi Kang ),신상희 ( Sang Hee Shin ),남미아 ( Mi A Nam ),이광우 ( Kwang Woo Lee ) 한국환경복원기술학회 2005 한국환경복원기술학회지 Vol.8 No.4

지반의 상호작용을 고려한 전면기초의 해석기법 개발

이재환,정상섬,이준규 한국지반공학회 2014 한국지반공학회논문집 Vol.30 No.12

The 3D numerical analysis is carried out to investigate the settlement behavior of flexible mat foundations subjectedto vertical loads. Special attention is given to the improved analytical method (YS-MAT) that reflects the mat flexibilityand soil spring coupling effect. The soil model captures the stiffness of the soil springs as well as the shear interactionbetween the soil springs. The proposed method has been validated by comparing the results with other numerical methodsand a field measurement on mat foundation. Through comparative studies, the settlement of the proposed method wasin relatively good agreement with those of a field measurement and other numerical methods. The results permit usto estimate the response of the mat foundation subjected to vertical loads that should be taken into account in thecombination of mat flexibility and soil continuity characteristics.

고농도 제설제 처리에서 토양 및 자생 초화류에 미치는 Blanket 식생매트의 효용성

주진희,이재만,김원태,임병옥,서남규,윤용한 한국환경과학회 2022 한국환경과학회지 Vol.31 No.3

This study investigated the effect of vegetation mat on plant growth and salt reduction in the soil treated with high concentration deicing salt. In order to measure soil chemical characteristics and plant growth, three native groundcover plants (Dendranthema zawadskii var. latilobum, Dendranthema boreale, and Kalimeris yomena) were grown in each of the three plastic containers (50.0 cm width × 35.0 cm length × 8.5 cm deep) with a high concentration treatment of calcium chloride deicing salt. There were two treatments: control, and BVM that combines B (blanket) and VM (vegetation mat). 1,600 g of soil was placed on the top of the drainage layer with 290 g of perlite, 100 seeds each of the three native plants with three repetitions were sowed, and 10 g/L of calcium chloride deicing salt was added in the treatment. As a result of the chemical properties of soil, soil in control treatment was acidic and soil electrical conductivity in BVM was the lowest. Also, exchangeable cations (K+, Ca2+, Na+, and Mg2+) in soil and all the three plants were significantly decreased in the BVM treatment. Meanwhile, the germination rate of Dendranthema zawadskii var. latilobum was the highest under high concentration deicing salt in compared to the two plants. Overall, three native groundcover plant growth was higher in the BVM than control treatment significantly. These results suggest that the treatment of blanket vegetation mat has a positive effect on soil and plant growth in soil damaged by deicing salt.