Caisson Quay Wall Research Articles

Dynamic behaviors of RC caisson subjected to underwater explosions

Due to the vulnerability of wharves against accidental attacks, the reinforced concrete (RC) caisson quay wall, as a widely adopted wharf form, is faced with the potential threat of underwater explosions. The present work aims to study the dynamic responses and damage modes of caisson against underwater explosions through the underwater explosion test and numerical simulations. Firstly, four shots of underwater explosion test were conducted, including two cases for different focuses, i.e., two shots of the free field underwater explosion with a charge weight of 0.2 and 1 kg respectively, and another two shots of a 1/5 reduced scale caisson specimen subjected to the underwater explosion with a charge weight of 0.2 and 1 kg successively. The underwater explosion overpressure-time histories and periods of bubble pulsation, as well as the deflection-time histories and damage modes of caisson specimen were experimentally obtained. Then, the refined finite element (FE) models were established, including the 1D model for explosion loading and the 3D model for predicting the dynamic behaviors of caisson with adopting the Coupled-Eulerian-Lagrangian algorithms and remapping technology, which were validated by comparing with the test data. Finally, the influences of explosion conditions, such as explosion standoff, depth of burst, and charge weight on the dynamic behaviors of caisson specimens were numerically discussed. It derives that, the existing calculation formulas of overpressure and period of bubble obtained from the spherical charge are also applicable to the group charge; the reflection coefficient of hydraulic RC structure is around 1.7; the bubble pulsation induced by the underwater explosion could further deteriorate the damage level of RC caisson when the blast wave has already led to an inelastic structural response. The present work could provide beneficial references for the blast-resistance evaluation and design of hydraulic RC structures against underwater explosions.

Effectiveness of concrete rigid inclusions for coastal reclaimed liquefiable soils

Various ground improvement methods have been utilized to reduce the risk of liquefaction and associated soil deformations. Limited research has been reported in literature pertaining the effectiveness of concrete rigid inclusions in reducing the liquefaction-induced deformations. This paper displays the outcomes of a numerical study that investigates the effectiveness of concrete rigid inclusions in mitigating liquefaction-induced deformation of coastal reclaimed liquefiable soils. For this purpose, series of numerical analyses using 2D finite element software package GeoStudio 2012 were performed for different replacement area ratios and inclusion lengths in reclaimed deposits. The case history of caisson quay wall in Rokko Island from 1995 Kobe earthquake was used as a basis for the analysis and for model verification. The results showed that concrete rigid inclusions technique is efficient in reducing the permanent liquefaction-induced horizontal and vertical deformations of coastal reclaimed backfill and foundation deposits and provides better performance for subjected coastal structures.

Numerical Back-analysis of Caisson Quay Walls in the Yeong-il Bay Port during the 2017 Pohang Earthquake

The performance of nonlinear response history analysis was analyzed based on the historic case of the 2017 Pohang earthquake in Korea. The Yeong-il bay container terminal stopped operations for a period after the Pohang earthquake and intensive site and hazard investigations were conducted. Nonlinear response history analyses using various soil constitutive models, including sophisticated liquefaction models, were performed on the caisson quay wall under two-dimensional plane strain condition. The results of analysis were compared to the hazard investigation results. The analysis results exhibit reasonable agreement with the field measurement data for the earthquake-induced permanent displacement of the quay wall and quay crane rails.

Dynamic pore water pressure of submerged backfill on caisson quay walls: 1 g shake table tests

This paper aims to investigate dynamic pore water pressure of submerged backfill on caisson quay walls implementing 1 g shake table physical model tests. The tests were performed on physical models instrumented with various types of transducers to record different aspects of the behavior of the quay walls and the backfill soil during shaking. The results showed that dynamic pore water pressures exerted on the quay walls were influenced by several parameters including relative density and permeability of the backfill, amplitude of base shaking, generation of excess pore water pressure in the backfill and lateral displacement of the quay wall. A comparison between the experimental results and the available analytical solutions demonstrated that the analytical solutions cannot accurately predict dynamic pore water pressures in backfills of intermediate permeability where soil-water interaction is substantial. Also, it was found that in the worst-case scenario, two out of three different dynamic thrusts exerted on the quay wall including active dynamic pressure of the backfill, dynamic pore water pressure and hydrodynamic pressure were in phase. Moreover, the variation of each of these pressures with depth was not necessarily in phase.

Optimization of deep mixing design for seismic liquefaction mitigation of Caisson walls

Gravity caisson wall is a common waterfront construction that were severely damaged by soil liquefaction in previous earthquakes. The deep mixing method is regarded as effective in liquefaction remediation. Meanwhile, an easily-executable remedial design procedure of using the deep mixing method for caisson walls exposed to seismic liquefaction risk has not been well developed for routine constructions. To solve the issue by following the philosophy of the Performance-Based Design method, the deep mixing method is examined within a framework of a well-calibrated case history to provide hypothetical mitigation to a damaged caisson wall to reach the acceptable level under the identical cyclic loadings as recorded in the case history. The study is divided into two steps: (1) a case history of damaged caisson wall by seismic-induced soil liquefaction was verified; (2) the deep mixing method is hypothetically applied to the caisson wall before the occurrence of earthquake, and the remedial design is optimized based on the improved wall structure deformation under seismic loading. The remedial design including the locations and configurations of deep mixing elements are optimized. Insights and recommendations on the establishment of liquefaction mitigation design and optimization process for caisson quay walls are provided to the practice.

Soil Liquefaction and Ground Settlements in 6 February 2018 Hualien, Taiwan, Earthquake

Research Article| October 10, 2018 Soil Liquefaction and Ground Settlements in 6 February 2018 Hualien, Taiwan, Earthquake Yung‐Yen Ko; Yung‐Yen Ko aDepartment of Civil Engineering, National Cheng Kung University, No. 1, University Road, Tainan 70101, Taiwan, yyko@mail.ncku.edu.tw Search for other works by this author on: GSW Google Scholar Shang‐Yi Hsu; Shang‐Yi Hsu bNational Center for Research on Earthquake Engineering, National Applied Research Laboratories, No. 200, Section 3, Hsinhai Road, Taipei 10668, Taiwan Search for other works by this author on: GSW Google Scholar Hsuan‐Chih Yang; Hsuan‐Chih Yang bNational Center for Research on Earthquake Engineering, National Applied Research Laboratories, No. 200, Section 3, Hsinhai Road, Taipei 10668, Taiwan Search for other works by this author on: GSW Google Scholar Chih‐Chieh Lu; Chih‐Chieh Lu bNational Center for Research on Earthquake Engineering, National Applied Research Laboratories, No. 200, Section 3, Hsinhai Road, Taipei 10668, Taiwan Search for other works by this author on: GSW Google Scholar Yu‐Wei Hwang; Yu‐Wei Hwang bNational Center for Research on Earthquake Engineering, National Applied Research Laboratories, No. 200, Section 3, Hsinhai Road, Taipei 10668, Taiwan Search for other works by this author on: GSW Google Scholar Chia‐Hung Liu; Chia‐Hung Liu bNational Center for Research on Earthquake Engineering, National Applied Research Laboratories, No. 200, Section 3, Hsinhai Road, Taipei 10668, Taiwan Search for other works by this author on: GSW Google Scholar Jin‐Hung Hwang Jin‐Hung Hwang cDepartment of Civil Engineering, National Central University, No. 300, Zhongda Road, Zhongli District, Taoyuan 32001, Taiwan Search for other works by this author on: GSW Google Scholar Seismological Research Letters (2019) 90 (1): 51–59. https://doi.org/10.1785/0220180196 Article history first online: 10 Oct 2018 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Yung‐Yen Ko, Shang‐Yi Hsu, Hsuan‐Chih Yang, Chih‐Chieh Lu, Yu‐Wei Hwang, Chia‐Hung Liu, Jin‐Hung Hwang; Soil Liquefaction and Ground Settlements in 6 February 2018 Hualien, Taiwan, Earthquake. Seismological Research Letters 2018;; 90 (1): 51–59. doi: https://doi.org/10.1785/0220180196 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietySeismological Research Letters Search Advanced Search ABSTRACT Soil liquefaction and ground settlements during an earthquake of ML 6.2 that took place on 6 February 2018 in Hualien, Taiwan are presented in this article based on the results of a field reconnaissance that focused on geotechnical aspects. Cracks of road pavement with sand eruption were found in a former wetland. Slight settlement of several residential buildings that are located near the Meilun River was observed. In addition, minor sand boils and lateral spreading occurred at the riverbanks of the Meilun and Hualien Rivers. In general, liquefaction and ground settlements in Hualien City were sparse and localized in weak ground, causing no damage to structures and facilities. However, in the Port of Hualien, ground settlements up to 50–60 cm, as well as considerable pavement cracks, were induced in the backland of several gravity‐type wharves, especially those in the jetty area. Many of the cracks and settlements were accompanied by eruption of the mixture of sand and gravel with a maximum grain size up to 10 cm. These phenomena were due to the liquefaction of the backfill material. Fortunately, there was only scarcely noticeable tilt and structural damage of the caisson quay walls and scarce settlement of the apron. Thus, the serviceability of these wharves was not greatly influenced. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Seismic Displacement Evaluation Chart Method for Caisson Quay Walls Improved by the Vibro-Compaction Method

Gravity type caisson walls are a type of popular but easily damaged waterfront construction structure, especially in seismic regions. Various forms of mitigation measures have been successfully and economically applied to improve their performances under the influence of soil liquefaction. Establishment of an effective, reliable, and easily-implemented liquefaction remedial design process based on a commonly used ground improvement technology is important for routine practice. To solve this problem, the vibro-compaction method, as one the most widely used accepted liquefaction remediation method, is applied as the countermeasure to improve a gravity type quay wall damaged by seismic-liquefaction in this study. More than three hundred cases of numerical analyses with variations of the improved zone configurations, improved soil properties and levels of seismic excitation loading were conducted. Based on the results of the parametric study, numerous correlations among various improved zone configurations, improved relative densities of the soils, excitation level, and improved performances of the caisson-wall structure are established. Therefore, a simple chart design procedure based on the established correlations is proposed to estimate the improved residual displacement of gravity caisson quay walls remediated by the vibro-compaction method. The results can be used as a convenient reference for liquefaction mitigation of gravity caisson wall using vibro-compaction method in routine practice.

Evaluation of Caisson Quay Wall Behavior during the 1995 Kobe Earthquake by Nonlinear Effective Stress Analysis

Evaluation of Caisson Quay Wall Behavior during the 1995 Kobe Earthquake by Nonlinear Effective Stress Analysis

Optimization of Vibrocompaction Design for Liquefaction Mitigation of Gravity Caisson Quay Walls

AbstractGravity-type caisson walls are a type of popular but easily damaged waterfront construction structure, especially in seismic regions. Various forms of mitigation have been successfully applied to improve their performance when subjected to liquefaction. Establishment of an effective, reliable, and easily implemented liquefaction remedial design procedure based on commonly used ground improvement technology is important. In this study, following the philosophy of performance-based design, a novel optimization process was developed and applied to a well-known case study. The vibrocompaction method was examined within a framework of a well-calibrated case history to hypothetically improve the seismic performance of a damaged caisson quay wall to an acceptable level. This study includes three major steps: first, the constitutive model used in this study for describing liquefaction was calibrated based on the published data; second, a caisson quay wall case history damaged by liquefaction was simulated...

Prediction method of seismic residual deformation of caisson quay wall in liquefied foundation

The multi-spring shear mechanism plastic model in this paper is defined in strain space to simulate pore pressure generation and development in sands under cyclic loading and undrained conditions, and the rotation of principal stresses can also be simulated by the model with cyclic behavior of anisotropic consolidated sands. Seismic residual deformations of typical caisson quay walls under different engineering situations are analyzed in detail by the plastic model, and then an index of liquefaction extent is applied to describe the regularity of seismic residual deformation of caisson quay wall top under different engineering situations. Some correlated prediction formulas are derived from the results of regression analysis between seismic residual deformation of quay wall top and extent of liquefaction in the relative safety backfill sand site. Finally, the rationality and the reliability of the prediction methods are validated by test results of a 120 g-centrifuge shaking table, and the comparisons show that some reliable seismic residual deformation of caisson quay can be predicted by appropriate prediction formulas and appropriate index of liquefaction extent.

Displacement reducer fuses for improving seismic performance of caisson quay walls

This research is to study the efficiency of displacement reducer fuses, installed behind the caisson quay walls for controlling the dynamic backfill thrust and minimizing the displacement, settlement and tilting of the walls. For this purpose, two types of fuses, Displacement Reducer Panels (DRP) and Displacement Reducer Elements (DRE), were constructed and installed behind the wall. The DRPs were constructed by hollow Polypropylene sheets to reproduce elastoplastic and plastic mechanical behaviors. The DREs were cylindrical stainless-steel dampers, working upon friction mechanism that can reproduce perfect plastic behavior. Here, two series of shaking table 1-g tests were performed with DRP and DRE applications. In this regard, different mechanical behaviors and capacities were considered for fuses against demand thrusts of backfill in order to compare the mitigation tests with no-mitigation cases. Harmonic base motions with constant amplitude and constant frequency were used in the model test. The foundation soil and the backfill soil were constructed with the relative densities of 85 and 25%, respectively, to reproduce non-liquefiable base layer and loose backfill situations in the model, respectively. The results showed remarkable reduction in kinetic energy, dynamic backfill thrust and consequently seaward movement, settlement and inclination of the caisson quay wall in case of using fuses with plastic behaviors behind the wall.

Soils and Foundations During Earthquakes

This paper provides an overview of the modern understanding of the behavior of soils and foundations during an earthquake based on the papers published in Soils and Foundations over the last fifty years. The most fundamental issues in geotechnical earthquake engineering are the non-linearity of soil under cyclic loading and its implications on the seismic performance of geotechnical structures. The non-linearity of granular materials is essentially anisotropic, whereas the linear or equivalent linear model often used in conventional practices is isotropic. The non-linearity of dry soil is characterized by the difference between the peak and residual strengths, and the increased awareness of the implications of this difference over time has allowed for the development of a generalized methodology for evaluating active earth pressures. The non-linearity of saturated soil under undrained cyclic shear differs fundamentally from that of dry soil, with saturated soil capable of mobilizing 100% of the shear strain in the double amplitude. The cyclic behavior of saturated soil under initial shear is typical of most seismic behaviors of geotechnical structures, including embankments, caisson quay walls, and underground structures. The liquefaction-induced flow failure of geotechnical structures is associated with the steady state of sand in the order of 10 kPa. However, the challenge in the coming decades will be to evaluate the combined effects due to cyclic loading and the steady state. Moreover, the effects of pore water migration are significant in the case of highly permeable geotechnical materials when evaluating settlement of the ground or addressing inter-layered structures of clay and sand. Although current research is elucidating the mechanics of partially saturated sands, the new challenge is to understand combined hazards, such as a combination of earthquake motions and tsunamis. Thus, new approaches and technologies need to be developed.

Studying the effects of deformable panels on seismic displacement of gravity quay walls

This research is to investigate the effects of deformable panels on reducing the seaward displacement, settlement and tilting of caisson quay walls. In this regard, a series of shaking table 1- g tests are performed for a 1 25 scaled-down caisson quay wall with two different seabed interface conditions. Here, the wall is tested in two cases: with and without (no-mitigation case) applying the deformable panels. Being installed behind the walls, the panels applied in the tests have different mechanical properties. In the model test, the harmonic base motions are used with constant frequency and amplitude. In all tests, the foundation soil beneath the caisson wall is assumed as dense and non liquefiable. However, in order to reproduce a loose backfill situation in the model, the backfill soil is constructed with relative density of 25%. Furthermore, to support the experimental results, a series of finite difference effective-stress analyses are performed in the prototype scale. The mitigation results show that the deformable panels can significantly decrease the seaward movement, settlement and inclination of wall as well as the total pressure recorded behind the caisson wall. Here, these panels are called Displacement Reducer Panels (DRP) based on the obtained results.

Underwater Shake Table Tests on Waterfront Structures Protected with Tire Chips Cushion

A series of large-scale underwater shaking table tests was performed on a gravity type model caisson protected by a cushioning technique using tire chips (scrap tire derived recycled product). The function of the tire chips cushion is to reduce the load and restricting the permanent displacement of such waterfront retaining structures during earthquakes by exploiting the compressibility, the ductility and the energy absorbing capacity of tire chips. The seismic performance of such earthquake resistant techniques was evaluated by subjecting the soil-structure system into three different earthquake loadings (two actual earthquake records and one synthetic earthquake), and measuring the respective responses. The results demonstrated that the seismic load against the caisson quay wall could be substantially reduced using the proposed technique. In addition, the presence of the protective tire chips cushion could significantly reduce the earthquake-induced residual displacement of the caisson quay wall.

Insight into seismic earth and water pressures against caisson quay walls

Motivated by the need to explain the large displacement and rotation that numerous caisson-type quay walls suffered in the port of Kobe during the devastating 1995 earthquake, a detailed numerical analysis is presented for the response of such a wall from Rokko Island. Utilising the Pastor–Zienkiewicz elastoplastic constitutive model, an effective stress dynamic analysis is performed using as input the accelerogram recorded 32 m below the ground surface in the nearby Port Island. The evolution during shaking of lateral displacements, plastic strains and pore water pressures sheds some light on the complex interplay of several simultaneously occurring phenomena: the development of oscillatory inertia forces on the wall, in phase or out of phase with the backfill soil and water pressures; the simple-shear seismic deformation of the soil and the ensuing initial development of positive excess pore water pressures in the backfill and the foundation soil; the extensional deformation developing in the ‘active wedge’ behind the wall, with the ensuing generation of negative excess pore water pressures; and the continuous dissipation and redistribution of water pressures. The conventional generalised Mononobe–Okabe theory is also reviewed, and extensive comparisons are made with the numerically computed effective and water pressures against the wall. Finally, a surprising role of the relative density of rubble behind the wall is highlighted.

Seismic Effective-Stress Analysis of Caisson Quay Walls: Application to Kobe

ABSTRACT Deformation-based seismic design of gravity quay-walls requires realistic computation of residual deformations. This article presents an effective-stress analysis method, which is based on an elasto-plastic constitutive model formulated into a finite-difference algorithm. The model is applicable to cohesionless soils, for a wide range of relative densities and confining pressures. The formulation is applied first to re-analyze one of the failed caisson-type quay-walls of Rokko Island during the 1995 Kobe (Hyogoken-nambu) earthquake (Case 1). Subsequently, it is applied to analyse three closely related case studies of quay-walls, subjected to the same earthquake excitation, to demonstrate the effects of ground improvement on the wall performance. Case 2 considers a quay-wall in which both the foundation and backfill consist of improved, non-liquefiable soils. Case 3 considers a quay-wall in which the backfill soil remains liquefiable, whereas the foundation soil has been improved. Finally, in Case 4 the foundation soil is liquefiable, and the backfill soil improved. The results are consistent with both field observations and earlier independent computer simulations by Iai et al. 1998 which were based on the finite-element method and a different constitutive model.

Earthquake Damage Mitigation of Existing Gravity Type Caisson Quay Wall by Sand Compaction Piles

Earthquake Damage Mitigation of Existing Gravity Type Caisson Quay Wall by Sand Compaction Piles

DEVELOPMENT OF EARTHQUAKE REINFORCEMENT METHOD FOR GRAVITY-TYPE QUAYWALL BY SHEET PILE INSTALLED AT THE FOOT OF THE CAISSON

The objective of this development is to increase the earthquake resistance performance of gravity caisson quay wall by employing sheet pile at the foot of the caisson. Gravity caisson quay wall with sheet pile realizes the 0.05 point increase of seismic coefficient by comparing usual gravity caisson quay wall. This method can apply existing gravity caisson quay wall which is short of sliding resistance during earthquake. Quay wall structure becomes hybrid type by connecting the head of sheet pile and the caisson and shows both advantages of gravity type structure and sheet pile structure. Underwater shaking table test and 2D dynamic effective stress analysis were done for the proposed hybrid type quay wall structure. Gravity caisson quay wall was designed at the condition of 0.15 design seismic coefficient and 10m water depth at the foot of the structure. The result shows the necessity of 900mmdia. steel sheet pile for the condition of 0.2 design seismic coefficient. 50 percent reduction of caisson crest displacement during earthquake is also obtained. Design criteria for this hybrid quay wall structure is also proposed.

EFFECT OF PILE LENGTH ON SEISMIC RESPONSE OF CAISSON TYPE QUAY WALL RESTING ON PILE FOUNDATION

Dynamic behavior of a caisson type quay wall resting on pile foundation against the 1995 Hyogoken Nanbu Earthquake was numerically evaluated by a liquefaction analysis based on effective stress model. The effect of pile length on seismic response of caisson type quay wall against earthquake motion was investigated through some numerical examples. The displacement response of the caisson quay wall with pile foundation was smaller than that of the caisson without pile foundation. When the pile length becomes longer, the displacement response of caisson type quay wall becomes smaller. As the deformation was mainly induced by the increase of pore water pressure in the soil behind the caisson type quay wall, it is indispensable to reduce the pore water pressure in case of applying longer pile to the caisson type quay wall.

Seismic Behavior of a Caisson Type Quay Wall Resting on Pile Foundation with Expanded Base

Dynamic behavior of a caisson type quay wall resting on pile foundation with exp anded base was numerically evaluated by a liquefaction analysis based on effective stress model during 1995 Hyogo-ken Nanbu Earthquake. The effective stress model used for the liquef action analysis during earthquake motion was a strain space multiple mechanism model. The deformation during the earthquake ground motion induced due to pore water press ure in the soil behind the caisson quay wall. Though the displacement response of the caisson q uay wall with pile foundation was smaller than that of the caisson without pile foundation, the deformation was mainly induced by the increase of pore water pressure.