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Pitthaya Jamsawang - One of the best experts on this subject based on the ideXlab platform.
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Effectiveness of deep Cement Mixing walls with top-down construction for deep excavations in soft clay: case study and 3D simulation
Acta Geotechnica, 2019Co-Authors: Pitthaya Jamsawang, Pornkasem Jongpradist, Panich Voottipruex, Pornpot Tanseng, Dennis T. BergadoAbstract:This paper presents the observed and simulated effectiveness of deep Cement Mixing walls created using top-down (DCM-TD) construction techniques for a deep excavation in soft Bangkok clay. The wall system consisted of four rows of 0.7-m-diameter DCM columns, and the bracing system consisted of two 0.25-m-thick basement slabs and seven temporary struts. The effectiveness of the wall system compared to that of other wall systems was evaluated using the measured results of previous case studies. A 3D numerical analysis was performed to calculate forces in the basement slabs and bending moments in the DCM wall. Finally, series of parametric analyses of both DCM-TD and deep Cement Mixing walls created using bottom-up (DCM-BU) construction techniques were carried out, and their results were compared to highlight the effectiveness of DCM-TD and its applicability to excavations at greater depths. The field and numerical results show that DCM-TD is more effective than DCM-BU in terms of the limitations of lateral wall movement, the bending moment in a DCM wall and the thickness of a DCM wall for various depths because of a larger system stiffness. Therefore, DCM-TD is very effective and suitable for use in potential future deep excavations in urban areas.
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bearing capacity and failure behaviors of floating stiffened deep Cement Mixing columns under axial load
Soils and Foundations, 2018Co-Authors: Anucha Wonglert, Pornkasem Jongpradist, Pitthaya Jamsawang, Stefan LarssonAbstract:Abstract This research aims to clarify and gain an insight into the impact of the length of the stiffened core and the strength of the deep Cement Mixing (DCM) socket on the behaviors of floating stiffened deep Cement Mixing (SDCM) columns. The observed behaviors include the axial ultimate bearing capacity, settlement and failure mode. The study begins by conducting a series of physical model tests as a preliminary investigation. The results reveal that the strength of the DCM socket can be reduced to a certain value by inserting a sufficiently long reinforced core to achieve the highest possible load-carrying capacity, indicating an optimum length of the stiffened core for a specific DCM socket strength. For a parametric study on the actual scale condition, full-scale load tests on a floating DCM and an SDCM column with eucalyptus wood as a core in the thick soft clay layer area were carried out to provide a reference case. The extended numerical analysis results suggest that the modes of failure depend on the length of the stiffened core and the strength of the DCM socket. The results from the numerical parametric study were used to establish a guideline chart for suggesting the appropriate length of the core in accordance with the strength of the DCM socket of the floating SDCM columns. The field pile load test results also confirm that core materials with a lower strength and stiffness, such as eucalyptus wood, could potentially be used as a reinforced core.
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Parameters affecting the lateral movements of compound deep Cement Mixing walls by numerical simulations and parametric analyses
Acta Geotechnica, 2015Co-Authors: Pitthaya Jamsawang, Pornkasem Jongpradist, Panich Voottipruex, Dennis T. BergadoAbstract:A compound deep Cement Mixing retaining wall system is a combination of deep Cement Mixing (DCM) columns and precast reinforced concrete walls. This type of retaining wall was used in a deep excavation for a reservoir construction project in a soft clay area in Thailand. During construction, an inclinometer casing was installed to monitor the lateral movement profiles of this retaining wall system until construction had been completed. Studies on the parameters that affect the lateral movements of retaining walls of this type are limited because of the complex geometry involved. In this paper, a three-dimensional numerical model is first calibrated using an instrumented case history. Then, an analysis of the results for this case history is presented to characterize the wall behavior in terms of the ground settlement induced by wall deflection during excavation and in terms of lateral wall movement. Finally, a parametric study is performed. The results provide information on the influence exerted on the lateral wall movement by the following factors: the elastic modulus of the DCM columns, the embedded length of the DCM columns, the size of the DCM columns, the thickness of the precast wall, the thickness of the soft clay layer and the berm size. The influences of these factors are compared and rated in terms of their degree of importance.
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behavior and simulation of deep Cement Mixing dcm and stiffened deep Cement Mixing sdcm piles under full scale loading
Soils and Foundations, 2011Co-Authors: Panich Voottipruex, Dennis T. Bergado, Pitthaya Jamsawang, T Suksawat, W CheangAbstract:ABSTRACT A new kind of Deep Cement Mixing (DCM) pile called Stiffened Deep Mixing Pile (SDCM) is introduced to mitigate the low flexural strength and unexpected failures of DCM piles. A jet grouting method with a jet pressure of 22 MPa, was utilized in the installation of DCM piles. The SDCM pile consists of a DCM pile with a precast reinforced concrete core pile inserted at its center. Pile and embankment load tests were conducted, and then the results of the field load tests were simulated by a 3D finite element method (FEM) to back-analyze and confirm the related design parameters. These parameters were then used further in numerical experiments. The field test results showed that the settlements and lateral movements of the SDCM pile using a prestressed concrete core pile with area ratio (Acore/ADCM) of 0.17 and a length ratio of 0.85 was less than those of the DCM pile by 40% and 60%, respectively. Moreover, the SDCM pile foundation increased the bearing capacity by as much as 2.2 times. The average lateral pile capacity of the SDCM piles was 15 times higher than the DCM piles. A strength reduction factor of 0.40 was obtained at the concrete core and the DCM interface from the full scale pullout test. The behavior of both the DCM and SDCM piles was confirmed from the subsequent 3D FEM simulations. From the 3D FEM simulations, the length of the concrete core pile had more influence on the settlements of the SDCM pile than its cross-sectional area. However, both the length and cross-sectional area of concrete core pile affected the lateral resistance of the SDCM pile.
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field behaviour of stiffened deep Cement Mixing piles
Proceedings of the Institution of Civil Engineers - Ground Improvement, 2011Co-Authors: Pitthaya Jamsawang, Dennis T. Bergado, Panich VoottipruexAbstract:Full-scale pile load tests were performed on soft Bangkok clay improved by stiffened deep Cement Mixing (SDCM) piles and deep Cement Mixing (DCM) piles installed by jet-Mixing to compare their performance. The SDCM pile is a DCM pile with a precast reinforced concrete core pile inserted in the middle. A series of full-scale tests consisting of axial compression, lateral and pullout interface between the concrete core pile and surrounding DCM material were performed. The length of the concrete core pile influenced both the ultimate axial bearing capacity and the settlement of the SDCM piles more than its section area. Furthermore, the section area of the concrete core pile affected both the lateral ultimate bearing capacity and the lateral displaCements of SDCM piles significantly. Moreover, the SDCM piles with area ratio (Acore/ADCM) of 0·17 and length ratio (Lcore/LDCM) of 0·85 increased the axial and lateral ultimate bearing capacities so that they were as much as 2·2 and 15 times higher than the corres...
Dennis T. Bergado - One of the best experts on this subject based on the ideXlab platform.
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Effectiveness of deep Cement Mixing walls with top-down construction for deep excavations in soft clay: case study and 3D simulation
Acta Geotechnica, 2019Co-Authors: Pitthaya Jamsawang, Pornkasem Jongpradist, Panich Voottipruex, Pornpot Tanseng, Dennis T. BergadoAbstract:This paper presents the observed and simulated effectiveness of deep Cement Mixing walls created using top-down (DCM-TD) construction techniques for a deep excavation in soft Bangkok clay. The wall system consisted of four rows of 0.7-m-diameter DCM columns, and the bracing system consisted of two 0.25-m-thick basement slabs and seven temporary struts. The effectiveness of the wall system compared to that of other wall systems was evaluated using the measured results of previous case studies. A 3D numerical analysis was performed to calculate forces in the basement slabs and bending moments in the DCM wall. Finally, series of parametric analyses of both DCM-TD and deep Cement Mixing walls created using bottom-up (DCM-BU) construction techniques were carried out, and their results were compared to highlight the effectiveness of DCM-TD and its applicability to excavations at greater depths. The field and numerical results show that DCM-TD is more effective than DCM-BU in terms of the limitations of lateral wall movement, the bending moment in a DCM wall and the thickness of a DCM wall for various depths because of a larger system stiffness. Therefore, DCM-TD is very effective and suitable for use in potential future deep excavations in urban areas.
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prefabricated vertical drain pvd and deep Cement Mixing dcm stiffened dcm sdcm techniques for soft ground improvement
IOP Conference Series: Earth and Environmental Science, 2018Co-Authors: Dennis T. Bergado, P V Long, Salisa Chaiyaput, Aramugam BalasubramaniamAbstract:Soft ground improvement techniques have become most practical and popular methods to increase soil strength, soil stiffness and reduce soil compressibility including the soft Bangkok clay. This paper focuses on comparative performances of prefabricated vertical drain (PVD) using surcharge, vacuum and heat preloading as well as the Cement-admixed clay of Deep Cement Mixing (DCM) and Stiffened DCM (SDCM) methods. The Vacuum-PVD can increase the horizontal coefficient of consolidation, Ch, resulting in faster rate of settlement at the same magnitudes of settlement compared to Conventional PVD. Several field methods of applying vacuum preloading are also compared. Moreover, the Thermal PVD and Thermal Vacuum PVD can increase further the coefficient of horizontal consolidation, Ch, with the associated reduction of kh/ks values by reducing the drainage retardation effects in the smear zone around the PVD which resulted in faster rates of consolidation and higher magnitudes of settlements. Furthermore, the equivalent smear effect due to non-uniform consolidation is also discussed in addition to the smear due to the mechanical installation of PVDs. In addition, a new kind of reinforced deep Mixing method, namely Stiffened Deep Cement Mixing (SDCM) pile is introduced to improve the flexural resistance, improve the field quality control, and prevent unexpected failures of the Deep Cement Mixing (DCM) pile. The SDCM pile consists of DCM pile reinforced with the insertion of precast reinforced concrete (RC) core. The full scale test embankment on soft clay improved by SDCM and DCM piles was also analysed. Numerical simulations using the 3D PLAXIS Foundation finite element software have been done to understand the behavior of SDCM and DCM piles. The simulation results indicated that the surface settlements decreased with increasing lengths of the RC cores, and, at lesser extent, increasing sectional areas of the RC cores in the SDCM piles. In addition, the lateral movements decreased by increasing the lengths (longer than 4 m) and, the sectional areas of the RC cores in the SDCM piles. The results of the numerical simulations closely agreed with the observed data and successfully verified the parameters affecting the performances and behavior of both SDCM and DCM piles.
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Parameters affecting the lateral movements of compound deep Cement Mixing walls by numerical simulations and parametric analyses
Acta Geotechnica, 2015Co-Authors: Pitthaya Jamsawang, Pornkasem Jongpradist, Panich Voottipruex, Dennis T. BergadoAbstract:A compound deep Cement Mixing retaining wall system is a combination of deep Cement Mixing (DCM) columns and precast reinforced concrete walls. This type of retaining wall was used in a deep excavation for a reservoir construction project in a soft clay area in Thailand. During construction, an inclinometer casing was installed to monitor the lateral movement profiles of this retaining wall system until construction had been completed. Studies on the parameters that affect the lateral movements of retaining walls of this type are limited because of the complex geometry involved. In this paper, a three-dimensional numerical model is first calibrated using an instrumented case history. Then, an analysis of the results for this case history is presented to characterize the wall behavior in terms of the ground settlement induced by wall deflection during excavation and in terms of lateral wall movement. Finally, a parametric study is performed. The results provide information on the influence exerted on the lateral wall movement by the following factors: the elastic modulus of the DCM columns, the embedded length of the DCM columns, the size of the DCM columns, the thickness of the precast wall, the thickness of the soft clay layer and the berm size. The influences of these factors are compared and rated in terms of their degree of importance.
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behavior and simulation of deep Cement Mixing dcm and stiffened deep Cement Mixing sdcm piles under full scale loading
Soils and Foundations, 2011Co-Authors: Panich Voottipruex, Dennis T. Bergado, Pitthaya Jamsawang, T Suksawat, W CheangAbstract:ABSTRACT A new kind of Deep Cement Mixing (DCM) pile called Stiffened Deep Mixing Pile (SDCM) is introduced to mitigate the low flexural strength and unexpected failures of DCM piles. A jet grouting method with a jet pressure of 22 MPa, was utilized in the installation of DCM piles. The SDCM pile consists of a DCM pile with a precast reinforced concrete core pile inserted at its center. Pile and embankment load tests were conducted, and then the results of the field load tests were simulated by a 3D finite element method (FEM) to back-analyze and confirm the related design parameters. These parameters were then used further in numerical experiments. The field test results showed that the settlements and lateral movements of the SDCM pile using a prestressed concrete core pile with area ratio (Acore/ADCM) of 0.17 and a length ratio of 0.85 was less than those of the DCM pile by 40% and 60%, respectively. Moreover, the SDCM pile foundation increased the bearing capacity by as much as 2.2 times. The average lateral pile capacity of the SDCM piles was 15 times higher than the DCM piles. A strength reduction factor of 0.40 was obtained at the concrete core and the DCM interface from the full scale pullout test. The behavior of both the DCM and SDCM piles was confirmed from the subsequent 3D FEM simulations. From the 3D FEM simulations, the length of the concrete core pile had more influence on the settlements of the SDCM pile than its cross-sectional area. However, both the length and cross-sectional area of concrete core pile affected the lateral resistance of the SDCM pile.
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field behaviour of stiffened deep Cement Mixing piles
Proceedings of the Institution of Civil Engineers - Ground Improvement, 2011Co-Authors: Pitthaya Jamsawang, Dennis T. Bergado, Panich VoottipruexAbstract:Full-scale pile load tests were performed on soft Bangkok clay improved by stiffened deep Cement Mixing (SDCM) piles and deep Cement Mixing (DCM) piles installed by jet-Mixing to compare their performance. The SDCM pile is a DCM pile with a precast reinforced concrete core pile inserted in the middle. A series of full-scale tests consisting of axial compression, lateral and pullout interface between the concrete core pile and surrounding DCM material were performed. The length of the concrete core pile influenced both the ultimate axial bearing capacity and the settlement of the SDCM piles more than its section area. Furthermore, the section area of the concrete core pile affected both the lateral ultimate bearing capacity and the lateral displaCements of SDCM piles significantly. Moreover, the SDCM piles with area ratio (Acore/ADCM) of 0·17 and length ratio (Lcore/LDCM) of 0·85 increased the axial and lateral ultimate bearing capacities so that they were as much as 2·2 and 15 times higher than the corres...
Panich Voottipruex - One of the best experts on this subject based on the ideXlab platform.
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Effectiveness of deep Cement Mixing walls with top-down construction for deep excavations in soft clay: case study and 3D simulation
Acta Geotechnica, 2019Co-Authors: Pitthaya Jamsawang, Pornkasem Jongpradist, Panich Voottipruex, Pornpot Tanseng, Dennis T. BergadoAbstract:This paper presents the observed and simulated effectiveness of deep Cement Mixing walls created using top-down (DCM-TD) construction techniques for a deep excavation in soft Bangkok clay. The wall system consisted of four rows of 0.7-m-diameter DCM columns, and the bracing system consisted of two 0.25-m-thick basement slabs and seven temporary struts. The effectiveness of the wall system compared to that of other wall systems was evaluated using the measured results of previous case studies. A 3D numerical analysis was performed to calculate forces in the basement slabs and bending moments in the DCM wall. Finally, series of parametric analyses of both DCM-TD and deep Cement Mixing walls created using bottom-up (DCM-BU) construction techniques were carried out, and their results were compared to highlight the effectiveness of DCM-TD and its applicability to excavations at greater depths. The field and numerical results show that DCM-TD is more effective than DCM-BU in terms of the limitations of lateral wall movement, the bending moment in a DCM wall and the thickness of a DCM wall for various depths because of a larger system stiffness. Therefore, DCM-TD is very effective and suitable for use in potential future deep excavations in urban areas.
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Parameters affecting the lateral movements of compound deep Cement Mixing walls by numerical simulations and parametric analyses
Acta Geotechnica, 2015Co-Authors: Pitthaya Jamsawang, Pornkasem Jongpradist, Panich Voottipruex, Dennis T. BergadoAbstract:A compound deep Cement Mixing retaining wall system is a combination of deep Cement Mixing (DCM) columns and precast reinforced concrete walls. This type of retaining wall was used in a deep excavation for a reservoir construction project in a soft clay area in Thailand. During construction, an inclinometer casing was installed to monitor the lateral movement profiles of this retaining wall system until construction had been completed. Studies on the parameters that affect the lateral movements of retaining walls of this type are limited because of the complex geometry involved. In this paper, a three-dimensional numerical model is first calibrated using an instrumented case history. Then, an analysis of the results for this case history is presented to characterize the wall behavior in terms of the ground settlement induced by wall deflection during excavation and in terms of lateral wall movement. Finally, a parametric study is performed. The results provide information on the influence exerted on the lateral wall movement by the following factors: the elastic modulus of the DCM columns, the embedded length of the DCM columns, the size of the DCM columns, the thickness of the precast wall, the thickness of the soft clay layer and the berm size. The influences of these factors are compared and rated in terms of their degree of importance.
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behavior and simulation of deep Cement Mixing dcm and stiffened deep Cement Mixing sdcm piles under full scale loading
Soils and Foundations, 2011Co-Authors: Panich Voottipruex, Dennis T. Bergado, Pitthaya Jamsawang, T Suksawat, W CheangAbstract:ABSTRACT A new kind of Deep Cement Mixing (DCM) pile called Stiffened Deep Mixing Pile (SDCM) is introduced to mitigate the low flexural strength and unexpected failures of DCM piles. A jet grouting method with a jet pressure of 22 MPa, was utilized in the installation of DCM piles. The SDCM pile consists of a DCM pile with a precast reinforced concrete core pile inserted at its center. Pile and embankment load tests were conducted, and then the results of the field load tests were simulated by a 3D finite element method (FEM) to back-analyze and confirm the related design parameters. These parameters were then used further in numerical experiments. The field test results showed that the settlements and lateral movements of the SDCM pile using a prestressed concrete core pile with area ratio (Acore/ADCM) of 0.17 and a length ratio of 0.85 was less than those of the DCM pile by 40% and 60%, respectively. Moreover, the SDCM pile foundation increased the bearing capacity by as much as 2.2 times. The average lateral pile capacity of the SDCM piles was 15 times higher than the DCM piles. A strength reduction factor of 0.40 was obtained at the concrete core and the DCM interface from the full scale pullout test. The behavior of both the DCM and SDCM piles was confirmed from the subsequent 3D FEM simulations. From the 3D FEM simulations, the length of the concrete core pile had more influence on the settlements of the SDCM pile than its cross-sectional area. However, both the length and cross-sectional area of concrete core pile affected the lateral resistance of the SDCM pile.
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field behaviour of stiffened deep Cement Mixing piles
Proceedings of the Institution of Civil Engineers - Ground Improvement, 2011Co-Authors: Pitthaya Jamsawang, Dennis T. Bergado, Panich VoottipruexAbstract:Full-scale pile load tests were performed on soft Bangkok clay improved by stiffened deep Cement Mixing (SDCM) piles and deep Cement Mixing (DCM) piles installed by jet-Mixing to compare their performance. The SDCM pile is a DCM pile with a precast reinforced concrete core pile inserted in the middle. A series of full-scale tests consisting of axial compression, lateral and pullout interface between the concrete core pile and surrounding DCM material were performed. The length of the concrete core pile influenced both the ultimate axial bearing capacity and the settlement of the SDCM piles more than its section area. Furthermore, the section area of the concrete core pile affected both the lateral ultimate bearing capacity and the lateral displaCements of SDCM piles significantly. Moreover, the SDCM piles with area ratio (Acore/ADCM) of 0·17 and length ratio (Lcore/LDCM) of 0·85 increased the axial and lateral ultimate bearing capacities so that they were as much as 2·2 and 15 times higher than the corres...
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investigation and simulation of behavior of stiffened deep Cement Mixing sdcm piles
International Journal of Geotechnical Engineering, 2008Co-Authors: Pitthaya Jamsawang, Dennis T. Bergado, A Bandari, Panich VoottipruexAbstract:AbstractThe low strength and stiffness of Deep Cement Mixing (DCM) pile causes unexpected failure that has been mitigated with the introduction of stiffened deep Cement Mixing (SDCM) pile. The SDCM is a new type of DCM pile reinforced by concrete core pile. In this paper, the interface behavior of SDCM pile and its strength have been studied by various laboratory tests. The Cement content was varied from 10 to 20% by dry weight of clay and mixed at the water content corresponding to its liquid limit to obtain optimum strengths. The interface friction between the core concrete pile and the Cement-admixed clay was studied by means of the direct shear interface tests and K o pullout interface tests. The 15% Cement content yielded optimum interface shear strength. The CIU triaxial compression test of model SDCM pile revealed that the concrete core pile length should be more than 75% of the DCM pile length in order to have significant improvement. The physical modeling together with numerical modelin...
Pornkasem Jongpradist - One of the best experts on this subject based on the ideXlab platform.
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parametric analysis and optimization of t shaped and conventional deep Cement Mixing column supported embankments
Computers and Geotechnics, 2020Co-Authors: Chana Phutthananon, Pornkasem Jongpradist, Pattaramon Jongpradist, Daniel Dias, Julien BarothAbstract:Abstract The aim of this article was to optimize the shape and modulus of T-shaped deep Cement Mixing (TDM) and conventional deep Cement Mixing (DCM) columns for supporting embankment over soft soil. Objective of optimization is minimizing the column costs and differential settlement while maximizing the stress efficacy. A 2D axisymmetric numerical modelling was employed to investigate the behavior of TDM and DCM column-supported embankments. The influence of each parameter of the column-embankment system (CES) on differential settlement and stress efficacies is presented and discussed. The optimization approach using a genetic algorithm (GA) combined with a response surface method (RSM) was used to find an optimal solution. The numerical optimization results show that the use of optimal TDM column can provide lower differential settlement and higher stress efficacies compared to the conventional DCM column under the same or even lower column construction costs.
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Effectiveness of deep Cement Mixing walls with top-down construction for deep excavations in soft clay: case study and 3D simulation
Acta Geotechnica, 2019Co-Authors: Pitthaya Jamsawang, Pornkasem Jongpradist, Panich Voottipruex, Pornpot Tanseng, Dennis T. BergadoAbstract:This paper presents the observed and simulated effectiveness of deep Cement Mixing walls created using top-down (DCM-TD) construction techniques for a deep excavation in soft Bangkok clay. The wall system consisted of four rows of 0.7-m-diameter DCM columns, and the bracing system consisted of two 0.25-m-thick basement slabs and seven temporary struts. The effectiveness of the wall system compared to that of other wall systems was evaluated using the measured results of previous case studies. A 3D numerical analysis was performed to calculate forces in the basement slabs and bending moments in the DCM wall. Finally, series of parametric analyses of both DCM-TD and deep Cement Mixing walls created using bottom-up (DCM-BU) construction techniques were carried out, and their results were compared to highlight the effectiveness of DCM-TD and its applicability to excavations at greater depths. The field and numerical results show that DCM-TD is more effective than DCM-BU in terms of the limitations of lateral wall movement, the bending moment in a DCM wall and the thickness of a DCM wall for various depths because of a larger system stiffness. Therefore, DCM-TD is very effective and suitable for use in potential future deep excavations in urban areas.
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bearing capacity and failure behaviors of floating stiffened deep Cement Mixing columns under axial load
Soils and Foundations, 2018Co-Authors: Anucha Wonglert, Pornkasem Jongpradist, Pitthaya Jamsawang, Stefan LarssonAbstract:Abstract This research aims to clarify and gain an insight into the impact of the length of the stiffened core and the strength of the deep Cement Mixing (DCM) socket on the behaviors of floating stiffened deep Cement Mixing (SDCM) columns. The observed behaviors include the axial ultimate bearing capacity, settlement and failure mode. The study begins by conducting a series of physical model tests as a preliminary investigation. The results reveal that the strength of the DCM socket can be reduced to a certain value by inserting a sufficiently long reinforced core to achieve the highest possible load-carrying capacity, indicating an optimum length of the stiffened core for a specific DCM socket strength. For a parametric study on the actual scale condition, full-scale load tests on a floating DCM and an SDCM column with eucalyptus wood as a core in the thick soft clay layer area were carried out to provide a reference case. The extended numerical analysis results suggest that the modes of failure depend on the length of the stiffened core and the strength of the DCM socket. The results from the numerical parametric study were used to establish a guideline chart for suggesting the appropriate length of the core in accordance with the strength of the DCM socket of the floating SDCM columns. The field pile load test results also confirm that core materials with a lower strength and stiffness, such as eucalyptus wood, could potentially be used as a reinforced core.
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Parameters affecting the lateral movements of compound deep Cement Mixing walls by numerical simulations and parametric analyses
Acta Geotechnica, 2015Co-Authors: Pitthaya Jamsawang, Pornkasem Jongpradist, Panich Voottipruex, Dennis T. BergadoAbstract:A compound deep Cement Mixing retaining wall system is a combination of deep Cement Mixing (DCM) columns and precast reinforced concrete walls. This type of retaining wall was used in a deep excavation for a reservoir construction project in a soft clay area in Thailand. During construction, an inclinometer casing was installed to monitor the lateral movement profiles of this retaining wall system until construction had been completed. Studies on the parameters that affect the lateral movements of retaining walls of this type are limited because of the complex geometry involved. In this paper, a three-dimensional numerical model is first calibrated using an instrumented case history. Then, an analysis of the results for this case history is presented to characterize the wall behavior in terms of the ground settlement induced by wall deflection during excavation and in terms of lateral wall movement. Finally, a parametric study is performed. The results provide information on the influence exerted on the lateral wall movement by the following factors: the elastic modulus of the DCM columns, the embedded length of the DCM columns, the size of the DCM columns, the thickness of the precast wall, the thickness of the soft clay layer and the berm size. The influences of these factors are compared and rated in terms of their degree of importance.
W Cheang - One of the best experts on this subject based on the ideXlab platform.
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behavior and simulation of deep Cement Mixing dcm and stiffened deep Cement Mixing sdcm piles under full scale loading
Soils and Foundations, 2011Co-Authors: Panich Voottipruex, Dennis T. Bergado, Pitthaya Jamsawang, T Suksawat, W CheangAbstract:ABSTRACT A new kind of Deep Cement Mixing (DCM) pile called Stiffened Deep Mixing Pile (SDCM) is introduced to mitigate the low flexural strength and unexpected failures of DCM piles. A jet grouting method with a jet pressure of 22 MPa, was utilized in the installation of DCM piles. The SDCM pile consists of a DCM pile with a precast reinforced concrete core pile inserted at its center. Pile and embankment load tests were conducted, and then the results of the field load tests were simulated by a 3D finite element method (FEM) to back-analyze and confirm the related design parameters. These parameters were then used further in numerical experiments. The field test results showed that the settlements and lateral movements of the SDCM pile using a prestressed concrete core pile with area ratio (Acore/ADCM) of 0.17 and a length ratio of 0.85 was less than those of the DCM pile by 40% and 60%, respectively. Moreover, the SDCM pile foundation increased the bearing capacity by as much as 2.2 times. The average lateral pile capacity of the SDCM piles was 15 times higher than the DCM piles. A strength reduction factor of 0.40 was obtained at the concrete core and the DCM interface from the full scale pullout test. The behavior of both the DCM and SDCM piles was confirmed from the subsequent 3D FEM simulations. From the 3D FEM simulations, the length of the concrete core pile had more influence on the settlements of the SDCM pile than its cross-sectional area. However, both the length and cross-sectional area of concrete core pile affected the lateral resistance of the SDCM pile.