The Experts below are selected from a list of 288 Experts worldwide ranked by ideXlab platform
Dennes T. Bergado - One of the best experts on this subject based on the ideXlab platform.
-
Comparative performances of two- and three-dimensional analyses of soil-cement mixing columns under an Embankment load
Marine Georesources & Geotechnology, 2018Co-Authors: Pitthaya Jamsawang, Dennes T. Bergado, Panich Voottipruex, Ekkarin Phongphinittana, Pornkasem JongpradistAbstract:AbstractThis research presents measurements and simulations of the full-scale behavior of a Test Embankment built on a soft marine clay deposit improved using soil–cement mixing (SCM) columns in Ba...
-
performance of full scale Test Embankment with reinforced lightweight geomaterials on soft ground
Lowland technology international : the official journal of the International Association of Lowland Technology, 2008Co-Authors: T. Tanchaisawat, Dennes T. Bergado, Panich Voottipruex, S HayashiAbstract:4 ABSTRACT: Embankment construction using reinforced lightweight geomaterials over soft ground will alleviate problems of instability and large settlements. Backfills of retaining structures can also be constructed using lightweight materials resulting in lower vertical loads and, consequently, reduced settlements. The aim of this study is to investigate the behavior of lightweight geomaterials consisting of tire chip-sand mixture reinforced with geogrids for use as Embankment construction on soft ground. The experimental results indicated that the mixing ratio of 30:70 % was the most suitable fill material. The full scale field Test Embankment was constructed at the campus of Asian Institute of Technology (AIT) in Bangkok, Thailand. The geogrid reinforced Embankment system was extensively instrumented in the subsoil and within the Embankment itself in order to observe its behavior during construction and post construction phases, and thereby evaluate its performance. The unit weight of rubber tire chip-sand mixtures is about 75% lighter than conventional sand. The total settlement at ground surface is 67.5% less when compared to the conventional backfill without foundation treatments. The maximum lateral wall movement observed at 13 months after construction at top of wall is 45% smaller when compared to conventional sand backfill on untreated ground. Finally, the geogrid reinforcements correspond well with the bilinear type of maximum tension line.
-
Numerical simulation and sensitivity analyses of full-scale Test Embankment with reinforced lightweight geomaterials on soft Bangkok clay
Geotextiles and Geomembranes, 2008Co-Authors: T. Tanchaisawat, Dennes T. Bergado, Panich VoottipruexAbstract:A full-scale Test Embankment was constructed on soft Bangkok clay using rubber tire chip–sand mixture as a lightweight geomaterial reinforced with geogrid under working stress conditions. The facing of the Embankment was made of segmental concrete blocks with rock filled gabion boxes as the facing to the sloping sides. This paper attempts to simulate the behavior of the full-scale Test Embankment using PLAXIS finite element 2D program by means of undrained analysis in the construction stage and thereafter consolidation analysis was performed during the service stage. The settlement predictions of the soft clay foundation mostly depended on the assumed thickness of the weathered crust and the OCR values of the soft clay layer. The predicted excess pore water pressures were sensitive to the OCR values of the soft clay layer. The lateral wall movements were overpredicted by the analysis due to the partially drained consolidation process at the early stage of the construction. The FEM computed geogrid movements were smaller than the observed field data due to the use of lightweight tire chips-sand backfill. The maximum tension line agreed reasonably well with the coherent gravity bilinear failure plane. The sensitivity analyses of settlements, excess pore water pressures, lateral wall movements, geogrid movements and tensions in geogrid were performed by varying the weathered crust thickness, the OCR values of soft clay, the permeability values of the soft clay and the interface coefficient of the geogrid. The settlements and the excess pore water pressures changed significantly when the OCR and the permeability values of soft clay were varied. The interface coefficient of the geogrid reinforcements affected the lateral wall movements, geogrid movements and tensions in the geogrids. The higher interface coefficient yielded less wall/geogrid movement and resulted in higher tensions in geogrids as expected. The results of analyses show that the FEM analysis using 2D plane strain conditions provided satisfactory predictions for the field performance.
-
Chapter 11 A full-scale study on cement deep mixing in soft Bangkok clay
Ground Improvement — Case Histories, 2005Co-Authors: Dennes T. Bergado, Glen A. LorenzoAbstract:Abstract A case history of full-scale deep mixing improved soft clay ground overlain by a 6.0 m high reinforced Test Embankment is presented. The deep mixing piles were constructed in the ground using the jet mixing technique with cement slurry employing a jet pressure of 20 MPa. Comparison was made to another reinforced Test Embankment of almost the same height constructed previously on unimproved soft clay foundation. Excess pore pressure buildrup during soil-cement pile installation by jet mixing was monitored. The surface and settlements as well as lateral movements were monitored during and after Embankment construction. The deep mixing improvement has effectively reduced the settlement and lateral movement of the foundation soil by as much as 70% and 80%, respectively. The local differential settlement between deep mixing pile and its surrounding soil amounted to 8–20% of the average total settlement of the improved ground, and could induce downdrag skin friction on the pile.
-
Innovations and performances of PVD and dual function geosynthetic applications
Geotextiles and Geomembranes, 2004Co-Authors: G.a. Lorenzo, Dennes T. Bergado, W. Bunthai, D. Hormdee, P. PhothiraksanonAbstract:Abstract Full-scale Test Embankments, which were constructed on separate locations but within the site of the Second Bangkok International Airport and at the Campus of the Asian Institute of Technology, confirmed that prefabricated vertical drain (PVD) installation not only accelerated and facilitated uniform consolidation settlements but also aided in recharging the subsoil. Thus, PVD can mitigate the negative piezometric drawdown of the subsoil caused by the excessive pumping of groundwater down to the depth of PVD installation. The compressibility and flow parameters were back-calculated from the performance of the full-scale Tests. Further back-analysis proved that every stage of preloading corresponded with certain rate of consolidation, and hence the variation of compressibility parameters of PVD-improved soft clay. Another full-scale Test Embankment employing vacuum-assisted preloading revealed that the rate of settlement has increased by 60% and the period of preloading was reduced by 4 months. Moreover, the use of electro-conductive PVDs could further shorten the required time of consolidation. In addition, dual function geosynthetic had been proposed to prevent excavation slope failures caused by the drawdown of water level along irrigation/drainage canals.
Norma Patricia López-acosta - One of the best experts on this subject based on the ideXlab platform.
-
Performance monitoring and numerical assessment of a Test Embankment with preloading and vertical drains on Texcoco lacustrine soft clays
Geotextiles and Geomembranes, 2020Co-Authors: Alejandra Liliana Espinosa-santiago, Norma Patricia López-acostaAbstract:Abstract This paper presents the performance monitoring results and long-term numerical analyses of a 2.8-m-high Test Embankment with vertical drains on soft highly compressible clays during a four years and two months observation period (1525 days). The peculiar study site is characterized by thick layers of lacustrine soft clay with water contents up to 300%, void ratios between 7 and 9 and ratios Cα/Cc range from 0.06 to 0.03. The loading applied by the Test Embankment was 43.4 kPa. The vertical drains installed were of two types: sand and prefabricated. The settlements that only take into account the effect of the preloading Embankment at the end of the observation period were 2.62 m and 2.71 m, in the zones with sand and prefabricated vertical drains, respectively. The settlement measured by regional subsidence was 0.47 m. The ultimate primary settlement was approximately 2.0 m and was estimated by two observational methods based on field settlement records. The settlement developed by secondary consolidation in the Embankment ranged from 0.62 m to 0.71 m at the end of the observation period. The Test Embankment behavior was simulated by 2D and 3D numerical analyses. The 2D analyses used a theory to convert the axisymmetric drainage into plane drainage. The long-term numerical results and the field measurements were compared and discussed.
-
Performance of a Test Embankment on very soft clayey soil improved with drain-to-drain vacuum preloading technology
Geotextiles and Geomembranes, 2019Co-Authors: Norma Patricia López-acosta, Alejandra Liliana Espinosa-santiago, V.m. Pineda-núñez, Alexandra Ossa, M.j. Mendoza, Efraín Ovando-shelley, E. BoteroAbstract:Abstract Vacuum consolidation of soils is a technology that, to date, has not been implemented in the Valley of Mexico, where clays are highly compressible and have very low shear resistance and low permeability. This paper describes the experience of a Test Embankment, in which the drain-to-drain vacuum preloading was assessed. The evaluation includes the description of the subsoil conditions, characteristics of the Embankment, construction process and instrumentation that was installed. The Test lasted approximately one year with a vacuum applied for six months. The monitoring results showed that the vacuum distributed along the vertical drains and on the surface soil layers accelerated the consolidation, reduced the lateral displacements toward the outside of the platform and increased the effective stress of the soil to a depth similar to the length of the drains. However, there were vacuum pressure losses of approximately 30% between the pumps and end of the horizontal flexible pipes that distribute the vacuum. These losses of vacuum pressure affected the soil consolidation process.
Panich Voottipruex - One of the best experts on this subject based on the ideXlab platform.
-
Comparative performances of two- and three-dimensional analyses of soil-cement mixing columns under an Embankment load
Marine Georesources & Geotechnology, 2018Co-Authors: Pitthaya Jamsawang, Dennes T. Bergado, Panich Voottipruex, Ekkarin Phongphinittana, Pornkasem JongpradistAbstract:AbstractThis research presents measurements and simulations of the full-scale behavior of a Test Embankment built on a soft marine clay deposit improved using soil–cement mixing (SCM) columns in Ba...
-
2D and 3D simulation of geogrid-reinforced geocomposite material Embankment on soft Bangkok clay
Geosynthetics International, 2009Co-Authors: T. Tanchaisawat, D T Bergado, Panich VoottipruexAbstract:ABSTRACT: A full-scale Test Embankment, 6.0 m high, was constructed on soft Bangkok clay using a rubber tire chip–sand mixture as a geocomposite material reinforced with geogrid reinforcement with concrete block facing in the middle portion of the Embankment. Silty sand backfill with rock-filled gabion facing were utilized at the sloping sides. The vertical and lateral deformations as well as excess pore pressures were monitored for 1 year. This study attempted to simulate the behavior of the full-scale Test Embankment by two-dimensional (2D) and three-dimensional (3D) numerical analyses. The 2D analysis was performed by PLAXIS software using undrained analysis in the construction stage and, thereafter, consolidation analysis was performed during the service stage. The 3D analysis was investigated by FLAC3D software using the same constitutive models and properties of foundation soils as published by previous researchers. Owing to the use of geocomposite material as Embankment materials, the observed valu...
-
performance of full scale Test Embankment with reinforced lightweight geomaterials on soft ground
Lowland technology international : the official journal of the International Association of Lowland Technology, 2008Co-Authors: T. Tanchaisawat, Dennes T. Bergado, Panich Voottipruex, S HayashiAbstract:4 ABSTRACT: Embankment construction using reinforced lightweight geomaterials over soft ground will alleviate problems of instability and large settlements. Backfills of retaining structures can also be constructed using lightweight materials resulting in lower vertical loads and, consequently, reduced settlements. The aim of this study is to investigate the behavior of lightweight geomaterials consisting of tire chip-sand mixture reinforced with geogrids for use as Embankment construction on soft ground. The experimental results indicated that the mixing ratio of 30:70 % was the most suitable fill material. The full scale field Test Embankment was constructed at the campus of Asian Institute of Technology (AIT) in Bangkok, Thailand. The geogrid reinforced Embankment system was extensively instrumented in the subsoil and within the Embankment itself in order to observe its behavior during construction and post construction phases, and thereby evaluate its performance. The unit weight of rubber tire chip-sand mixtures is about 75% lighter than conventional sand. The total settlement at ground surface is 67.5% less when compared to the conventional backfill without foundation treatments. The maximum lateral wall movement observed at 13 months after construction at top of wall is 45% smaller when compared to conventional sand backfill on untreated ground. Finally, the geogrid reinforcements correspond well with the bilinear type of maximum tension line.
-
Numerical simulation and sensitivity analyses of full-scale Test Embankment with reinforced lightweight geomaterials on soft Bangkok clay
Geotextiles and Geomembranes, 2008Co-Authors: T. Tanchaisawat, Dennes T. Bergado, Panich VoottipruexAbstract:A full-scale Test Embankment was constructed on soft Bangkok clay using rubber tire chip–sand mixture as a lightweight geomaterial reinforced with geogrid under working stress conditions. The facing of the Embankment was made of segmental concrete blocks with rock filled gabion boxes as the facing to the sloping sides. This paper attempts to simulate the behavior of the full-scale Test Embankment using PLAXIS finite element 2D program by means of undrained analysis in the construction stage and thereafter consolidation analysis was performed during the service stage. The settlement predictions of the soft clay foundation mostly depended on the assumed thickness of the weathered crust and the OCR values of the soft clay layer. The predicted excess pore water pressures were sensitive to the OCR values of the soft clay layer. The lateral wall movements were overpredicted by the analysis due to the partially drained consolidation process at the early stage of the construction. The FEM computed geogrid movements were smaller than the observed field data due to the use of lightweight tire chips-sand backfill. The maximum tension line agreed reasonably well with the coherent gravity bilinear failure plane. The sensitivity analyses of settlements, excess pore water pressures, lateral wall movements, geogrid movements and tensions in geogrid were performed by varying the weathered crust thickness, the OCR values of soft clay, the permeability values of the soft clay and the interface coefficient of the geogrid. The settlements and the excess pore water pressures changed significantly when the OCR and the permeability values of soft clay were varied. The interface coefficient of the geogrid reinforcements affected the lateral wall movements, geogrid movements and tensions in the geogrids. The higher interface coefficient yielded less wall/geogrid movement and resulted in higher tensions in geogrids as expected. The results of analyses show that the FEM analysis using 2D plane strain conditions provided satisfactory predictions for the field performance.
-
Finite element modeling of hexagonal wire reinforced Embankment on soft clay
Canadian Geotechnical Journal, 2000Co-Authors: Dennes T. Bergado, Chairat Teerawattanasuk, Sompote Youwai, Panich VoottipruexAbstract:A full-scale Test Embankment was constructed on soft Bangkok clay using hexagonal wire mesh as reinforcement. This paper attempts to simulate the behavior of the full-scale Test Embankment using the finite element program PLAXIS. The agreement between the finite element results and the field data is quite good. The important considerations for simulating the behavior of the reinforced wall Embankment were the method of applying the Embankment loading during the construction process, the variation of soil permeability during the consolidation process, and the selection of the appropriate model and properties at the interface between the soil and reinforcement. The increased reinforcement stiffness tends to increase the reinforcement tension and increase the Embankment forward rotation. The reinforcement tensions increased with the compression of the underlying soft foundation. The appropriate interface properties between the backfill soil and the hexagonal wire mesh reinforcement corresponding to the inter...
Chiwan Wayne Hsieh - One of the best experts on this subject based on the ideXlab platform.
-
Stabilization of a Vertical Tire Chip Embankment with Geogrids
Transportation Research Record, 2000Co-Authors: Chiwan Wayne HsiehAbstract:A research project that involves the construction of a full-size geogrid-reinforced Test Embankment was conducted. Waste tire chips were used as the lightweight backfill for the Embankment. The joint research project involved participants from government agencies, academic research institutes, consulting firms, and material suppliers. To meet the function requirements, the north side of the Embankment had to be built essentially as a vertical wall. To maintain stability, the vertical side of the Embankment was reinforced with geogrids and covered with segmental retaining-wall facing. The objectives of the research study were to evaluate the feasibility of using waste tire chips as Embankment backfill material when coupled with geogrid reinforcement and to evaluate the performance of various types of goesynthetic drainage products in the Test Embankment. To minimize settlement due to compression of the tire chips, various combinations of tire chips and soil mixtures or interlayers were used in the embankme...
Alejandra Liliana Espinosa-santiago - One of the best experts on this subject based on the ideXlab platform.
-
Performance monitoring and numerical assessment of a Test Embankment with preloading and vertical drains on Texcoco lacustrine soft clays
Geotextiles and Geomembranes, 2020Co-Authors: Alejandra Liliana Espinosa-santiago, Norma Patricia López-acostaAbstract:Abstract This paper presents the performance monitoring results and long-term numerical analyses of a 2.8-m-high Test Embankment with vertical drains on soft highly compressible clays during a four years and two months observation period (1525 days). The peculiar study site is characterized by thick layers of lacustrine soft clay with water contents up to 300%, void ratios between 7 and 9 and ratios Cα/Cc range from 0.06 to 0.03. The loading applied by the Test Embankment was 43.4 kPa. The vertical drains installed were of two types: sand and prefabricated. The settlements that only take into account the effect of the preloading Embankment at the end of the observation period were 2.62 m and 2.71 m, in the zones with sand and prefabricated vertical drains, respectively. The settlement measured by regional subsidence was 0.47 m. The ultimate primary settlement was approximately 2.0 m and was estimated by two observational methods based on field settlement records. The settlement developed by secondary consolidation in the Embankment ranged from 0.62 m to 0.71 m at the end of the observation period. The Test Embankment behavior was simulated by 2D and 3D numerical analyses. The 2D analyses used a theory to convert the axisymmetric drainage into plane drainage. The long-term numerical results and the field measurements were compared and discussed.
-
Performance of a Test Embankment on very soft clayey soil improved with drain-to-drain vacuum preloading technology
Geotextiles and Geomembranes, 2019Co-Authors: Norma Patricia López-acosta, Alejandra Liliana Espinosa-santiago, V.m. Pineda-núñez, Alexandra Ossa, M.j. Mendoza, Efraín Ovando-shelley, E. BoteroAbstract:Abstract Vacuum consolidation of soils is a technology that, to date, has not been implemented in the Valley of Mexico, where clays are highly compressible and have very low shear resistance and low permeability. This paper describes the experience of a Test Embankment, in which the drain-to-drain vacuum preloading was assessed. The evaluation includes the description of the subsoil conditions, characteristics of the Embankment, construction process and instrumentation that was installed. The Test lasted approximately one year with a vacuum applied for six months. The monitoring results showed that the vacuum distributed along the vertical drains and on the surface soil layers accelerated the consolidation, reduced the lateral displacements toward the outside of the platform and increased the effective stress of the soil to a depth similar to the length of the drains. However, there were vacuum pressure losses of approximately 30% between the pumps and end of the horizontal flexible pipes that distribute the vacuum. These losses of vacuum pressure affected the soil consolidation process.