• Title/Summary/Keyword: adjacent ground settlement

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The Retaining wall Design nearby Large Excavation for Developed Underground in Urban Area. (도심지 지하공간개발을 위한 대형 대심도 근접굴착 흙막이 설계사례)

  • Shin, Yung-Wok;Park, Jong-Min;Lee, Sung-Hwan;Lee, Bong-Yeol;Lee, Jung-Young;Chang, Huck-Su
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.10a
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    • pp.49-83
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    • 2005
  • ESCP Project showed an urban excavation case and introduced design method for case of Soil-Structure behavior in urban excavation. In this case, a retaining structures design to analysis the behavior of retaining wall and adjacent structures in urban excavations was applied by using a Elasto-plastic beam and limit Equilibrium analysis and soil-structure interaction analysis. Reliable design of earth retaining structures and the ground adjacent to braced wall in urban excavation are often difficult due to many variable factors. The ground settlement and the damage of adjacent structures in urban excavation has been an imprtant issue. Therefore, the stability of the adjacent structures must be secured with the excavation support and research on the protection of adjacent structure is necessary.

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A Comparison of Analysis Methods on Mechanical Behavior of Stone Column Reinforced in the Soft Sabkha Deposit (연약 암염층(Sabkha)에 보강된 스톤컬럼의 침하거동에 관한 해석방법 비교연구)

  • Kim, Se-Won;Lee, Chul-Ho;Kim, Ki-Ho;Choi, Hang-Seok
    • Journal of the Korean Geotechnical Society
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    • v.27 no.1
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    • pp.53-63
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    • 2011
  • In this study, a composite behavior of stone columns reinforced in a soft ground, Sabkha, has been evaluated by performing a series of field measurements and numerical analyses. Field load tests were performed to verify the effect of the composite ground reinforced by stone columns in Kayan, Saudi. The settlement measured in the field test was compared with the settlement calculated by the Priebe method and the numerical analysis using ABAQUS. It is found that the settlement estimated using the Priebe method significantly overestimated the settlement measured in the field test. In addition, it is confirmed that consideration of confining effect exerted by surrounding adjacent stone columns in a numerical simulation is indispensable to estimate accurately the settlement of stone column composite ground.

Impact of adjacent excavation on the response of cantilever sheet pile walls embedded in cohesionless soil

  • Singh, Akshay Pratap;Chatterjee, Kaustav
    • Geomechanics and Engineering
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    • v.30 no.3
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    • pp.293-312
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    • 2022
  • Cantilever sheet pile walls having section thinner than masonry walls are generally adopted to retain moderate height of excavation. In practice, a surcharge in the form of strip load of finite width is generally present on the backfill. So, in the present study, influence of strip load on cantilever sheet pile walls is analyzed by varying the width of the strip load and distance from the cantilever sheet pile walls using finite difference based computer program in cohesionless soil modelled as Mohr-Coulomb model. The results of bending moment, earth pressure, deflection and settlement are presented in non-dimensional terms. A parametric study has been conducted for different friction angle of soil, embedded depth of sheet pile walls, different magnitudes and width of the strip load acting on the ground surface and at a depth below ground level. The result of present study is also validated with the available literature. From the results presented in this study, it can be inferred that optimum behavior of cantilever sheet pile walls is observed for strip load having width 2 m to 3 m on the ground surface. Further as the depth of strip load below the ground surface increases below the ground level to 0.75 times excavation height, the bending moment, settlement, net earth pressure and deflection decreases and then remains constant.

Investigation of pile group response to adjacent twin tunnel excavation utilizing machine learning

  • Su-Bin Kim;Dong-Wook Oh;Hyeon-Jun Cho;Yong-Joo Lee
    • Geomechanics and Engineering
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    • v.38 no.5
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    • pp.517-528
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    • 2024
  • For numerous tunnelling projects implemented in urban areas due to limited space, it is crucial to take into account the interaction between the foundation, ground, and tunnel. In predicting the deformation of piled foundations and the ground during twin tunnel excavation, it is essential to consider various factors. Therefore, this study derived a prediction model for pile group settlement using machine learning to analyze the importance of various factors that determine the settlement of piled foundations during twin tunnelling. Laboratory model tests and numerical analysis were utilized as input data for machine learning. The influence of each independent variable on the prediction model was analyzed. Machine learning techniques such as data preprocessing, feature engineering, and hyperparameter tuning were used to improve the performance of the prediction model. Machine learning models, employing Random Forest (RF), eXtreme Gradient Boosting (XGB), and Light Gradient Boosting Machine (LightGBM, LGB) algorithms, demonstrate enhanced performance after hyperparameter tuning, particularly with LGB achieving an R2 of 0.9782 and RMSE value of 0.0314. The feature importance in the prediction models was analyzed and PN was the highest at 65.04% for RF, 64.81% for XGB, and PCTC (distance between the center of piles) was the highest at 31.32% for LGB. SHAP was utilized for analyzing the impact of each variable. PN (the number of piles) consistently exerted the most influence on the prediction of pile group settlement across all models. The results from both laboratory model tests and numerical analysis revealed a reduction in ground displacement with varying pillar spacing in twin tunnels. However, upon further investigation through machine learning with additional variables, it was found that the number of piles has the most significant impact on ground displacement. Nevertheless, as this study is based on laboratory model testing, further research considering real field conditions is necessary. This study contributes to a better understanding of the complex interactions inherent in twin tunnelling projects and provides a reliable tool for predicting pile group settlement in such scenarios.

Sequential Analysis of Adjacent Ground Behaviors Caused by Deep Excavations (굴착 공정별 주변지반 거동 분석)

  • Seo Min-Woo;Seok Jeong-Woo;Yang Ku-Seung;Kim Myoung-Mo
    • Journal of the Korean Geotechnical Society
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    • v.22 no.2
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    • pp.19-28
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    • 2006
  • Long-term field observations were performed in three excavation sites in order to investigate the displacement behavior of adjacent ground during overall excavation procedure, where the depths of deep excavations were 15 m$\∼$29 m. In this study, ground settlements and lateral displacements of braced wall measured during installation of retaining wall and removal of bracing were specially focused to evaluate the behavior quantitatively according to three-stage-divided procedure, i.e. pre-excavation, main excavation, and removal of bracing. Through field measurements on three excavation sites, lateral displacements induced during removal of bracing are approximate to 40$\%$ of the amount found during main excavation stage and additional adjacent ground deformation during post-excavation procedure ranges from 18$\%$ to 33$\%$ of that found during main excavation stage, based on the settlement volume. In conclusion, it was quantitatively identified in this study that the deformations of adjacent ground during pre- and post-excavation stage were not negligible.

Development of Real Time Monitoring Program Using Geostatistics and GIS (GIS 및 지구통계학을 이용한 실시간 통합계측관리 프로그램 개발)

  • Han, Byung-Won;Park, Jae-Sung;Lee, Dae-Hyung;Lee, Gye-Choon;Kim, Sung-Wook
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.03a
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    • pp.1046-1053
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    • 2006
  • In the large scale recent reclaiming works performed within the wide spatial boundary, evaluation of long-term consolidation settlement and residual settlement of the whole construction area is sometimes made with the results of the limited ground investigation and measurement. Then the reliability of evaluation has limitations due to the spatial uncertainty. Additionally, in case of large scale deep excavation works such as urban subway construction, there are a lot of hazardous elements to threaten the safety of underground pipes or adjacent structures. Therefore it is necessary to introduce a damage prediction system of adjacent structures and others. For the more accurate analysis of monitoring information in the wide spatial boundary works and large scale urban deep excavations, it is necessary to perform statistical and spatial analysis considering the geographical spatial effect of ground and monitoring information in stead of using diagrammatization method based on a time-series data expression that is traditionally used. And also it is necessary that enormous ground information and measurement data, digital maps are accumulated in a database, and they are controlled in a integrating system. On the abovementioned point of view, we developed Geomonitor 2.0, an Internet based real time monitoring program with a new concept by adding GIS and geo-statistical analysis method to the existing real time integrated measurement system that is already developed and under useful use. The new program enables the spatial analysis and database of monitoring data and ground information, and helps the construction- related persons make a quick and accurate decision for the economical and safe construction.

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Numerical Analysis of Track Irregularity in Excavation Adjacent to Railway Trackbed (수치해석을 통한 철도노반 인접 굴착 시 궤도틀림 분석)

  • Seokjun Lee;Dongwook Oh;Seongmin Jang;Batchimeg, Banzragchgarav;Hyuksang, Jung
    • Journal of the Korean GEO-environmental Society
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    • v.24 no.12
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    • pp.39-45
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    • 2023
  • In this paper, a track irregularity according to adjacent deep excavation of railway was analyzed using three-dimensional numerical analysis. The construction for excavation adjacent to the railway track is likely to have a negative impact on train operations. Despite mandatory assessments of the stability and impact on adjacent structures during construction, reports continue to indicate ongoing settlement and track irregularity resulting from construction. Changes in the groundwater level and stress state of the ground due to excavation are pointed out as causes for settlement and track irregularity in structures adjacent to the excavation. In this study, therefore, numerical analysis was conducted taking into account factors that induce track irregularity during adjacent excavation work as variables. The KRL-2012 standard train load was applied to simulate operating trains. As a results, The position of the train load, the distance from the excavation point, had a significant impact on track irregularity, and there was a significant occurrence of track misalignment when the train load was applied. The impact of the groundwater level was not significant.

A Method of Obtaining Correction Factor for Settlement Prediction of Soft Ground Using Correlation of Theoretical and Measured Settlement of Gimhae-Jinyoung through SPSS Analysis (이론 및 계측 침하량의 SPSS 상관분석을 통한 김해진영 연약 지반의 침하량 예측 보정계수 산출법)

  • Jang, Won-Cheol;Kim, Byoung-Il;Kim, Young-Uk
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.5
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    • pp.502-508
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    • 2021
  • Predicting the settlement of soft ground is an important aspect of soft ground design. In this study, a method is proposed that increases the reliability of settlement predictions based on-site investigation data, including piezocone penetration test results, at the Gimhae-Jinyoung district, adjacent area to the Nakdong River. Soils in the area waweres classified using the Robertson Chart (1986, 1990), and theoretical settlement was calculated using the equations proposed by Terzaghi (1925) and Sanglerat (1972). SPSS was used to obtain the correlation between theoretical and measured settlements. Results produced settlement prediction errors for the Terzaghi and Sanglerat methods of 17.28% and 26.96%, respectively. A correction factor calculated by SPSS correlation analysis for the relation between and theoretical and measured settlements is proposed that improves the reliability of settlement prediction in soils of the classification examined.

A parametric study of settlement and load transfer mechanism of piled raft due to adjacent excavation using 3D finite element analysis

  • Karira, Hemu;Kumar, Aneel;Hussain Ali, Tauha;Mangnejo, Dildar Ali;Mangi, Naeem
    • Geomechanics and Engineering
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    • v.30 no.2
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    • pp.169-185
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    • 2022
  • The urbanization and increasing rate of population demands effective means of transportation system (basement and tunnels) as well as high-rise building (resting on piled foundation) for accommodation. Therefore, it unavoidable to construct basements (i.e., excavation) nearby piled foundation. Since the basement excavation inevitably induces soil movement and stress changes in the ground, it may cause differential settlements to nearby piled raft foundation. To understand settlement and load transfer mechanism in the piled raft due to excavation-induced stress release, numerical parametric studies are carried out in this study. The effects of excavation depths (i.e., formation level) relative to piled raft were investigated by simulating the excavation near the pile shaft (i.e., He/Lp=0.67), next to (He/Lp=1.00) and below the pile toe (He/Lp=1.33). In addition, effects of sand density and raft fixity condition were investigated. The computed results have revealed that the induced settlement, tilting, pile lateral movement and load transfer mechanism in the piled raft depends upon the embedded depth of the diaphragm wall. Additional settlement of the piled raft due to excavation can be account for apparent loss of load carrying capacity of the piled raft (ALPC). The highest apparent loss of piled raft capacity ALPC (on the account of induced piled raft settlement) of 50% was calculated in in case of He/Lp = 1.33. Furthermore, the induced settlement decreased with increasing the relative density from 30% to 90%. On the contrary, the tilting of the raft increases in denser ground. The larger bending moment and lateral force was induced at the piled heads in fixed and pinned raft condition.

An Experimental Investigation for the Effects of Pre-loading on the Ground Movement in Sand (선행하중 적용시 흙막이 벽체 및 주변지반의 거동에 관한 굴착모형실험)

  • 이봉열;김학문
    • Journal of the Korean Geotechnical Society
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    • v.19 no.5
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    • pp.15-26
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    • 2003
  • Urban excavation requires highly reliable prediction technique for the design and construction of earth retaining structure in order to protect adjacent structures around deep excavation. Application of the pre-loading of bracing for deep excavation has been reported, and the known beneficial effects are not fully understood and recognized by many practitioners. Model tests have been carried out to evaluate the efficiency of pre-loading system in reducing ground settlement as well as prediction of structural damage around excavation in sand. The test results revealed that the applied pre-loading of 50% and 70% showed about 20% of reduction in horizontal wall displacement and 30∼40% reduction in ground settlement. Also, bracing forces and earth pressure distribution behind the wall have been monitored during pre-loading at various excavation stages.