• Proceedings of the Korean Geotechical Society Conference
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• 1996.10a
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• pp.25-38
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• 1996

• Geomechanics and Engineering
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• v.34 no.4
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• pp.397-408
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• 2023

Pipe pile walls are commonly used as retaining structures for excavation projects, particularly in densely populated coastal cities such as Hong Kong. Pipe pile walls are preferred in reclaimed land due to their cost-effectiveness and convenience for installation. However, the pre-bored piling techniques used to install pipe piles can cause significant ground disturbance, posing risks to nearby sensitive structures. This study reports a well-documented case history in a reclamation site, and it was found that pipe piling could induce ground settlement of up to 100 mm. Statutory design submissions in Hong Kong typically specify a ground settlement alarm level of 10 mm, which is significantly lower than the actual settlement observed in this study. In addition, lateral soil movement of approximately 70 mm was detected in the marine deposit. The lateral soil displacement in the marine deposit was found to be up to 3.4 and 3.1 times that of sand fill and CDG, respectively, mainly due to the relatively low stiffness of the marine deposit. Based on the monitoring data and site-investigation data, a 3D numerical analysis was established to back-analyze soil movements due to the installation of the pipe pile wall. The comparison between measured and computed results indicates that the equivalent ground loss ratio is 20%, 40%, and 20% for the fill, marine deposit and CDG, respectively. The maximum ground settlement increases with an increase in the ground loss ratio of the marine deposit, whereas the associated influence radius remains stationary at 1.2 times the pipe pile wall depth (H). The maximum ground settlement increases rapidly when the thickness of marine deposit is less than 0.32H, particularly for the ground loss ratio of larger than 40%. This study provides new insights into the pipe piling construction in reclamation sites.

• Journal of the Korean GEO-environmental Society
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• v.13 no.12
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• pp.35-42
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• 2012

There are many large-scale coastal region landfill and land development by loading to use territory efficiently, this regions are mostly soft clay ground. Constructing structures and road on the soft ground bring about engineering problems like ground shear fracture and a big amount of consolidation by bearing capacity. Improvement of soft soil is required to secure soil strength and settlement control. In improvement of soft soil, predict for the amount of settlement based on field surveyed reports are important element for estimating pre-loading banking height and the final point of consolidation. In this study, there is calculating theoretical settlement by analyzing field surveyed report and ground investigation to improvement of soft soil with pre-loading and vertical drain method. And present settlement prediction method reflect soil characteristics in Gimpo Hangang site by analysing prediction settlement and observational settlement during compaction using hyperbolic, ${\sqrt{s}}$, Asaoka method.

• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.4
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• pp.418-428
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• 2017

In offshore area, newly deposited Quaternary loose seabed soils are widely distributed. There are a great number of offshore structures has been built on them in the past, or will be built on them in the future due to the fact that there would be no very dense seabed soil foundation could be chosen at planed sites sometimes. However, loosely deposited seabed foundation would bring great risk to the service ability of offshore structures after construction. Currently, the understanding on wave-induced liquefaction mechanism in loose seabed foundation has been greatly improved; however, the recognition on the consolidation characteristics and settlement estimation of loose seabed foundation under offshore structures is still limited. In this study, taking a semi-coupled numerical model FSSI-CAS 2D as the tool, the consolidation and settlement of loosely deposited sandy seabed foundation under an offshore breakwater is investigated. The advanced soil constitutive model Pastor-Zienkiewics Mark III (PZIII) is used to describe the quasi-static behavior of loose sandy seabed soil. The computational results show that PZIII model is capable of being used for settlement estimation problem of loosely deposited sandy seabed foundation. For loose sandy seabed foundation, elastic deformation is the dominant component in consolidation process. It is suggested that general elastic model is acceptable for subsidence estimation of offshore structures on loose seabed foundation; however, Young's modulus E must be dependent on the confining effective stress, rather than a constant in computation.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.2
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• pp.161-173
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• 2013

When the ground is excavated near the pre-existing structures due to the region restricted condition such as urban area, the ground will be released by the excavation and the temporary wall will be deformed depending on the earth pressure. In this case, issues can be created in terms of stability of pre-existing structures. Firstly, the laboratory model tests were carried out to investigate the ground surface settlement due to the ground excavation according to the excavation methods in this study. Using the ground surface settlement results from model tests, numerical analyses were carried out to study the structure deformation due to the ground excavation according to the excavation methods. Finally, using the structure deformation results from numerical analysis, the damage assessment of structures was carried out by using the strain damage estimation criterion.

• Journal of the Korean GEO-environmental Society
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• v.10 no.3
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• pp.63-71
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• 2009

The movement of in-situ walls has become very important as construction in large cities moves upward, instead of outward. Tall structures typically have deep excavations not on1y to provide extra space for parking, but also to reduce the potential settlement of the building. These large excavations require a robust bracing system to resist the lateral earth pressures as the depth increases. Methods to predict deflections of the retaining systems are of utmost importance because wall movements allow potentia1 settlement of adjacent structures. Case studies will be analyzed and measured waI1 def1ections will be compared with predictions from empirica1ly derived charts.

• Geomechanics and Engineering
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• v.34 no.6
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• pp.649-664
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• 2023

Structural inertial interaction is a representative the effect of dynamic soil-foundation-structure interaction (SFSI), which leads to a relative displacement between soil and foundation, period lengthening, and damping increasing phenomena. However, for a system with a significantly heavy foundation, the dynamic inertia of the foundation influences and interacts with the structural seismic response. The structure-to-foundation mass ratio (MR) quantifies the distribution of mass between the structure and foundation for a structure on a shallow foundation. Although both systems exhibit the same vertical factor of safety (FS_v), the MR and corresponding seismic responses attributed to the structure and foundation masses may differ. This study explored the influence of MR on the permanent deformation and seismic response of soil-foundation-structure system considering SFSI via numerical simulations. Given that numerous dimensionless parameters of SFSI described its influence on the structural seismic response, the parameters, except for MR and FS_v, were fixed for the sensitivity analysis. The results demonstrated that the foundation inertia of heavier foundations induced more settlement due to sliding behavior of heavily-loaded systems. Moreover, the structural inertia of heavier structures evidently exhibited foundation rocking behavior, which results in a more elongated natural period of the structure for lightly-loaded systems.

• Geomechanics and Engineering
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• v.34 no.6
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• pp.665-681
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• 2023

Liquefaction is one of the most devastating geotechnical phenomena that severely damage vital structures and lifelines. Before constructing structures on problematic ground, it is necessary to improve the site and solve the geotechnical problem. Among ground improvement methods dealing with liquefaction, gravel drain (GD) columns and deep soil mixing (DSM) columns are popular. In this study, the results of a series of seismic experiments in a 1g environment on a structure located over liquefiable ground with different thicknesses reinforced with GD and DSM techniques were presented. The dynamic response of the reinforced ground system was investigated based on the parameters of subsidence rate, excess pore water pressure ratio, and maximum acceleration. The time history of the input acceleration was applied harmonically with an acceleration range of 0.2g and at frequencies of 1, 2, and 3 Hz. The results show that the thickness of the liquefiable layer and the frequency of the input motion have a significant impact on the effectiveness of the improvement method and all responses. Among the two techniques used, DSM in thick liquefied layers was much more efficient than GD in controlling the subsidence and rupture of the soil under the foundation. Maximum settlement values, settlement rate, and foundation rotation in the thicker liquefied layer at the 1-Hz input frequency were higher than at other frequencies. At low thicknesses, the dynamic behavior of the GD was closer to that of the DSM.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.3923-3930
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• 2014

In this study, the physical and dynamic characteristics of soil were analyzed by selecting 3 sections as research subjects among road and structure construction sections in the construction site of the Gwangyang ${\bigcirc}{\bigcirc}$ industry area, and conducted consolidation analysis and bearing capacity assessments through Midas-GTS according to the construction conditions of the structures and section conditions of reinforcement using stabilized soil. The effects of improving the settlement and bearing capacity according to the improved effects of the stability and sections of reinforcement using stabilized soil in applying the reinforcement method using stabilized soil were analyzed as a solution for improving the settlement and bearing capacity of soft clay for constructing roads and structures. The improvement effects of the settlement and bearing capacity were outstanding when the reinforcement method using stabilized soil to the soft clay was applied. After applying the reinforcement method using stabilized soil, the holdback effect of the consolidation settlement was excellent by decreasing the volume of the consolidation settlement from a minimum of 53% to a maximum of 82%. When the width of the reinforcement using stabilized soil was twice the width of the constructed structure, it was found that the holdback effect of the consolidation settlement ranged from 1% to 7% through the width of reinforcement using stabilized soil. In addition, when applying reinforcement more than 6m in width and 1m in depth using stabilized soil, it was found that the increase in the allowable bearing capacity was 2.3 to 3.3 times more than that before applying the reinforcement, which suggests that the increase in bearing capacity by applying the reinforcement method using stabilized soil was significant.

• Wind and Structures
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• v.37 no.4
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• pp.275-287
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• 2023

Subgrade differential settlement of high-speed railways was a pivotal issue that could increase the risk of trains operation. The risk will be further increased when trains in the subsidence zone are affected by crosswinds. In this paper, the computational fluid dynamics (CFD) model and finite element (FE) model were established, and the data transmission interface of the two models was established by fluid-solid interaction (FSI) method to form a systematic crosswind-train-track-subgrade dynamic model. The risk of high-speed train encountering crosswind in settlement area was analyzed. The results showed that the aerodynamic force of the trains increased significantly with the increase in crosswind speed. The aerodynamic force of the trains could reach 125.14 kN, significantly increasing the risk of derailment and overturning. Considering the influence of crosswind, the risk of train operation could be greatly increased. The safety indices and the wheel-rail force both increased with the increase of the wind speed. For the high-speed train running at 350 km/h, the warning value of wind speed was 10.2 m /s under the condition of subgrade settlement with wavelength of 20 m and amplitude of 15 mm.