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Upgrading the caisson-type quay wall could be conducted by strengthening the rubble mound beneath the front caisson toe. Subsequently, the rubble in front of the wall is removed to increase the front water depth. This study assessed the dynamic response of the upgraded quay wall under earthquake loading and compared it to the existing case using a centrifuge test and numerical study. The tests were performed in a dry condition under six consecutive input waves with increasing magnitude. The results indicated that the upgrade significantly reduced the displacements of the quay wall. The deformation trend of the caisson also changed from overturning to slipping. A numerical study of the upgraded case was conducted using the PLAXIS 2D program in the dry condition to validate the model. In addition, the simulation in water was performed to realize the difference between the models with and without water. The numerical results were in good agreement with the experimental model. The deformed mode of the quay wall in the dry condition did not differ from that in water. However, the horizontal displacement of the quay wall in water was higher than in the dry condition, whereas the vertical component was slightly lower. [ABSTRACT FROM AUTHOR]

This article delves into the exploration of a significant sign, the "viśvavajra", found in the caisson ceilings of Buddhist esoteric art in Dunhuang's Mogao Caves. These caissons, featuring the viśvavajra sign in the center, were prevalent from the mid-Tang period to the Western Xia dynasty (ninth to thirteenth centuries) and are recorded by The Overall Record of Dunhuang Mogao Grottoes under description as "Jiaochu Jingxin". Similar caissons are also found in Western Buddhist Caves near Dunhuang, and Yulin Caves in Guazhou County, indicating a distinct regional character. Focusing on a well-preserved and intricately detailed example from Cave 361, this article aims to elucidate the specific tantric significance of the viśvavajra at the center of the caissons within the broader context of Buddhist art. Drawing from related tantras, the discussion explores how the sign and its surrounding compositions align with a particular homa (fire offering) maṇḍala, specifically the śāntika maṇḍala crucial to numerous Tantric Buddhist rituals. Furthermore, the article examines the evolution of caisson of this type of maṇḍala over time. By comparing the mid-Tang example from Cave 361 with the late Tang period's Cave 14, a noticeable shift in format becomes apparent. The viśvavajra sign takes on new significance, embodying "the samaya of all Tathāgatas". Ultimately, the article explores how the significance of the viśvavajra sign transforms into an allusion to Vairocana or Rocana under the Sino-Tibetan Esoteric Buddhist context in the Hexi Corridor during the early Northern Song and Western Xia dynasty. [ABSTRACT FROM AUTHOR]

Pillar restoration at the Alte Brücke Heidelberg Most people are probably familiar with the Alte Brücke Heidelberg as a photo motif. Built in 1788 as a masonry bridge made of sandstone, it spans the Neckar with seven arches with a view of Heidelberg Castle. However, what happened in the shadow of the bridge in recent years remained undiscovered by most people. During structural inspections in 2008 and 2016, damage was detected and documented on all pillars of the Alte Brücke Heidelberg, both in the water change zone and in the permanently dammed area. These were primarily foot washouts and damage to the natural sandstones. In addition, stone clamps were reworked and impact angles on the pillar tips were replaced and supplemented during these investigations. In order to carry out the necessary renovation work, the pillars had to be drained. Due to the adjacent shipping openings and the resulting tight space conditions, a slim caisson had to be constructed for this purpose, which could be placed exactly on the foundation base of the pillars and did not obstruct the ongoing shipping. The two‐part caisson had a total weight of almost 32 ts and was floated into place around the respective bridge pillars in short shipping blocks during the night using two specially assembled pontoons. The two halves of the caisson were then connected, lowered and anchored to the ground to create a closed, sealed working area around the bridge pillar. [ABSTRACT FROM AUTHOR]

Caisson gravity wharf has been developing into deep water, and the application of large caisson in unprotected sea area is increasing day by day, which puts forward higher requirements for caisson installation technology. In order to ensure the smooth installation of more than 5 200 tons of super large elliptical caisson in the No.2 berthing project in Chisha Operation Area of Qishagang District, Fangchenggang, and avoid the drawbacks of traditional manual control water injection process, the project team innovatively developed an intelligent caisson water injection system. The system consists of information acquisition equipment, data processing system and operation reaction terminal. By collecting and calculating the data of water level, flow rate and attitude, the caisson can be automatically fine-leveled. The system has been successfully applied in the No.2 berthing project of Chisha Operation Area, Qishagang District, Fangchenggang, and successfully completed the installation of 11 super large elliptical caissons with more than 5 200 tons, which improves the working efficiency, guarantees the project quality, reduces the construction safety risk, and has significant economic and social benefits, and has broad prospects for promotion and application. [ABSTRACT FROM AUTHOR]

Aare Bridge, Aarau (CH) A new bridge over the Aare was inaugurated in 2023 at a site where bridge structures have stood since Roman times. It connects the north bank with the old town of Aarau, the capital of the canton of Aargau, to the south. The new Aare bridge combines a modern interpretation of traditional aesthetics with functionality and efficiency. With a length of approx. 119 m, a width of 17.5 m, a main span of 44 m and two secondary spans of approx. 29 m, it has two lanes, sidewalks on both sides and bicycle lanes. The rational reinforced concrete construction is economical in its use of materials thanks to its thinned‐out geometry and hollow bodies. The bridge rests partly on the two caissons of the old bridge, which was built in 1949. The bridge structure is visually extended at its 4 extremities in the foreland by retaining walls, the lengths of which vary between 45 m and 89 m. The appearance of the bridge is inspired by the massive stone walls in Aarau. The light coloring of the concrete supports the dialogue with the surroundings. Where the bridge spans the riverside path, large openings offer a view across the water. On the side of the old town, there is an urban promenade with trees and, on the northern bank, green flower meadow areas and natural riverbank vegetation. [ABSTRACT FROM AUTHOR]

This article delves into the exploration of a significant sign, the “viśvavajra”, found in the caisson ceilings of Buddhist esoteric art in Dunhuang’s Mogao Caves. These caissons, featuring the viśvavajra sign in the center, were prevalent from the mid-Tang period to the Western Xia dynasty (ninth to thirteenth centuries) and are recorded by The Overall Record of Dunhuang Mogao Grottoes under description as “Jiaochu Jingxin”. Similar caissons are also found in Western Buddhist Caves near Dunhuang, and Yulin Caves in Guazhou County, indicating a distinct regional character. Focusing on a well-preserved and intricately detailed example from Cave 361, this article aims to elucidate the specific tantric significance of the viśvavajra at the center of the caissons within the broader context of Buddhist art. Drawing from related tantras, the discussion explores how the sign and its surrounding compositions align with a particular homa (fire offering) maṇḍala, specifically the śāntika maṇḍala crucial to numerous Tantric Buddhist rituals. Furthermore, the article examines the evolution of caisson of this type of maṇḍala over time. By comparing the mid-Tang example from Cave 361 with the late Tang period’s Cave 14, a noticeable shift in format becomes apparent. The viśvavajra sign takes on new significance, embodying “the samaya of all Tathāgatas”. Ultimately, the article explores how the significance of the viśvavajra sign transforms into an allusion to Vairocana or Rocana under the Sino-Tibetan Esoteric Buddhist context in the Hexi Corridor during the early Northern Song and Western Xia dynasty.

When a storm begins at low tide, the tide will increase with time. However, when a storm begins at high tide, the tide will decrease during the storm. Therefore, to achieve more accurate estimations of sliding distance, both the tide-level change and the tide level itself should be considered. In this study, a new approach to taking the change in tide level into account when calculating the sliding distance of gravity-type breakwaters during storms is proposed. Conducting the numerical analysis, we found that, when typhoons begin at low tide, the sliding distance of the breakwater increases when considering the change in tide level, and conversely, when they begin at high tide, the change in tide level results in the sliding distance being shortened. Therefore, considering the change in tide level with time can result in a more accurate and realistic estimation of the sliding distance of the breakwater being attained. This is expected to contribute greatly to the development of deformation-based performance design methods for breakwaters. [ABSTRACT FROM AUTHOR]

To adapt to the trend of prefabricated development in waterway transportation engineering, and promote the industrialization development of waterway transportation engineering in the design, industrialization manufacture, and assemble construction of prefabricated caissons, the process of block prefabrication, reinforcement connection, component lifting, wall panel joint treatment method, and structural impermeability of the prefabricated caissons were investigated through the design and experimental construction of the prefabricated caissons. The results show that the prefabricated scheme is feasible in general, and the application of this technology in the field of water transportation engineering is also prospected. [ABSTRACT FROM AUTHOR]

Based on the construction of berths No.9 and No.10 in the South Operation Area of Dalanping Port, Qinzhou Port, the quality control measures for underwater foundation treatment, caisson prefabrication, assembly and installation, surface structure construction, etc. were carried out through QC management methods according to the PDCA cycle in the construction of caisson gravity wharf. Feasible solutions have been proposed from six aspects: personnel, machinery, materials, methods, environment, and measurement, to address the instability of caissons caused by improper foundation treatment during the construction of gravity wharves, the large deviation of concrete component reinforcement protection layer that affects the service life of the structure, the unattractive overall shape of the wharf, and the structural safety caused by concrete cracking. It has improved the overall construction quality management level of the project, as well as the safety management level and economic benefits. [ABSTRACT FROM AUTHOR]

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Floating caissons can oscillate owing to ocean waves when towed to an installation site. To reduce these oscillations, free-surface anti-oscillation tanks mounted on floating caissons have been proposed. However, no coupled numerical model exists between the motion of the floating caisson and fluid flow in the tanks based on computational fluid dynamics (CFD). In this study, a coupled model is developed and compared to existing physical experiments for validation. In the coupled model, the vertical and rotational motion of the floating caisson are computed as a rigid body, and the motion of the free water in the tank is computed using a CFD model. Numerical results show the predictive capability of the coupled model in terms of the rotational motion (pitch) of the floating caisson within ±20% of experimental data, regardless of the absence or presence of water in the tank. The numerical results also show that the fluid flow with complex air–water interface motion in the tank can be analyzed in detail using the coupled model. This suggests that the coupled model developed in this study is a useful tool for quantitatively assessing the effectiveness of an anti-oscillation tank for reducing the pitch of a floating caisson. [ABSTRACT FROM AUTHOR]

The determination of soil parameters in geotechnical engineering and their variations during the construction process have long been a focal point for engineering designers. While the artificial neural network (ANN) has been employed for back analysis of soil parameters, its application to caisson sinking processes remains limited. This study focuses on the Nanjing Longtan Yangtze River Bridge project, specifically the south anchoring of an ultra-large rectangular caisson. A comprehensive analysis of the sinking process was conducted using 400 finite element method (FEM) models to obtain the structural stress and earth pressure at key locations. Multiple combinations of soil parameters were considered, resulting in a diverse set of simulation results. These results were then utilized as training samples to develop a back-propagating artificial neural network (BP ANN), which utilized the structural stress and earth pressure as input sets and the soil parameters as output sets. The BP ANN was individually trained for each stage of the sinking process. Subsequently, the trained ANN was employed to predict the soil parameters under different working conditions based on actual monitoring data from engineering projects. The obtained soil parameter variations were further analyzed, leading to the following conclusions: (1) The soil parameters estimated by the ANN exhibited strong agreement with the original values from the geological survey report, validating their reliability; (2) The surrounding soil during the caisson sinking exhibited three distinct states: a stable state prior to the arrival of the cutting edges, a strengthened state upon the arrival of the cutting edges, and a disturbed state after the passage of the cutting edges; (3) In the stable state, the soil parameters closely resembled the original values, whereas in the strengthened state, the soil strength and stiffness significantly increased, while the Poisson's ratio decreased. In the disturbed state, the soil strength and stiffness were slightly lower than the original values. This study represents a valuable exploration of back analysis for caisson engineering. The findings provide important insights for similar engineering design and construction projects. [ABSTRACT FROM AUTHOR]

Caissons are rigid foundation systems with huge mass that support a large variety of load combinations. Most studies ignore the resistance provided by the periphery of a caisson in providing resistance to applied external loading. In this study, the variation of resistive stresses generated on the base and sides of a caisson under various loading, interface, and seismic conditions, obtained from numerical analysis, is explored using finite-element method–based computer program ABAQUS. The shear forces and resistive moments thus generated have been studied to identify the resistive forces required for stability for different input parameters. The percentage of resisting moment shared by the caisson sides (lateral soil pressure, horizontal and vertical skin friction) has then been compared with that due to the caisson base (base reaction and base friction). Empirical correlation has been obtained using multiple linear regression analysis for the load shared by the caisson sides. It is observed that, with an increase in the horizontal and vertical seismic acceleration coefficients, the percentage of resisting moment contributed by the caisson sides increases. [ABSTRACT FROM AUTHOR]

The determination of seismic passive earth pressure resistance is of utmost importance during the analysis of geotechnical structures. In the present study, seismic passive earth pressure coefficient for caisson embedded in n‐layered soil is computed using modified pseudo‐dynamic method. Limit equilibrium method of analysis considering poly‐planar failure wedge has been adopted in the study and parametric variation of geometry of failure wedge has also been studied. The current study proposes formulation for variation of horizontal and vertical seismic acceleration profile with depth through various layers and studies the effect of number of layers, relative depths of various layers and relative soil friction angle in those layers, soil‐wall friction angle, horizontal and vertical seismic acceleration coefficients and normalized width of caisson. The study has been extended for submerged soil and the effect of excess pore pressure has been investigated. The results of the present study have been compared with previous theoretical studies and found to be in good agreement. It is observed that the extent of failure wedge formed in front of caisson increases with increasing soil friction angle, soil‐wall friction angle, horizontal seismic acceleration coefficient and width of caisson. [ABSTRACT FROM AUTHOR]

The penetration of spudcans have adverse effects on pre-existing bucket foundations during the blade lifting process of offshore wind power systems, which brings uncertainties for the design and construction of bucket foundations. This study employs the Euler-Lagrange method to explore the influence of spudcan penetration on the adjacent caissons in homogeneous clay within a large deformation finite element (LDFE) model. The LDFE model is validated against centrifuge tests data, with good agreement obtained. Parametric study is then conducted to explore, (i) the influence of the angle between vessel and caissons on the movements of the caisson, and (ii) potential influence factors on the movements of the caisson with an optimal angle between the vessel and caissons, including soil properties, dimensions of caisson and spudcan, and the distance between spudcan and caissons. The results show that 60° is the optimal angle between the vessel and caissons that results in the smallest movement of the caisson, and the caisson foundation inclination angle ranges between 0° and 0.025°, when the pile shoe penetration progress ranges between 0.1 and 1.0. An empirical formula is proposed to predict the rotational angle of caisson with the optimal angle. The study establishes a quantitative approach to assess the influence of the spudcan penetration on existing three-caisson jacket foundations, which provides guidance for the design and construction of offshore wind turbine bucket foundations. [ABSTRACT FROM AUTHOR]

Bridge failure is mostly caused by geotechnical failure. Because caissons are the automatic choice for foundation systems for marine structures, such as bridges and wind turbines, this study addresses the determination of seismic passive earth pressure coefficients for caissons. In the present study, a realistic three-dimensional (3D) failure wedge was assumed to be formed behind caissons of different widths on the basis of the past results of experimental and numerical studies. The limit equilibrium method of analysis was adopted to determine the seismic passive earth pressure coefficients due to the cohesion component, surcharge component, and unit weight component. The current study takes into account the relative width and depth of the geotechnical structure and returns a series of design charts and tables for different soil-soil friction angles, soil-wall friction angles, and horizontal and vertical seismic acceleration coefficients. The results were compared with previous experimental and theoretical studies and found to be in excellent agreement. [ABSTRACT FROM AUTHOR]

The influence of scale effect could be significant on the behavior of ring stiffened caisson penetrating into clay, which brings uncertainty when predicting the failure mechanism and penetration resistance. This paper presents numerical modeling results which examine the scale effect on the behavior of caisson during piling into clay, which can consider the plug effect of caisson installation that has significant effect on the behavior of caisson especially for the case with large L/D. Large deformation finite element analyses are employed in this study. Two numerical models are generated and validated with laboratory results from centrifuge tests. Numerical results demonstrate significant scale effect on the characteristics of caisson penetrating in clay, which is mainly influenced by the normalized soil strength. Two formulas, with considering scale effect, are proposed to predict the behavior of stiffened caisson during installation, which can provide engineering guidance for the design of installation for ring stiffened caissons. [ABSTRACT FROM AUTHOR]

Floating caissons can oscillate owing to ocean waves when towed to an installation site. To reduce these oscillations, free-surface anti-oscillation tanks mounted on floating caissons have been proposed. However, no coupled numerical model exists between the motion of the floating caisson and fluid flow in the tanks based on computational fluid dynamics (CFD). In this study, a coupled model is developed and compared to existing physical experiments for validation. In the coupled model, the vertical and rotational motion of the floating caisson are computed as a rigid body, and the motion of the free water in the tank is computed using a CFD model. Numerical results show the predictive capability of the coupled model in terms of the rotational motion (pitch) of the floating caisson within ±20% of experimental data, regardless of the absence or presence of water in the tank. The numerical results also show that the fluid flow with complex air–water interface motion in the tank can be analyzed in detail using the coupled model. This suggests that the coupled model developed in this study is a useful tool for quantitatively assessing the effectiveness of an anti-oscillation tank for reducing the pitch of a floating caisson.

A series of physical experiments were carried out to investigate the characteristics of the horizontal active earth pressure exerted by rubble stones placed in front of horizontally composite breakwaters. Typically, the shoulder width of rubble mounds is shorter than the failure wedge assumed by Rankine's earth pressure theory; therefore, it is not appropriate to apply the theory for the estimation of the horizontal pressure of rubble stones on the caisson. Considering this, physical experiments were conducted to evaluate the horizontal earth pressure with rubble stones having different shoulder widths in front of the caisson. The experimental results showed that the horizontal pressure was considerably lower than that obtained by Rankine's theory when the shoulder width was shorter than the failure wedge width. Even when the shoulder width was sufficiently large to apply the theory, the earth pressure was approximately 17% lower than the value calculated byRankine's theory. Based on these analyses, an empirical equation is proposed that can estimate the earth pressure on the caisson for a wide range of shoulder widths of rubble mounds. [ABSTRACT FROM AUTHOR]

• This study addresses the impact that the size and shape of the local scour hole have on both the monotonic bearing capacities and failure envelopes of suction caisson embedded in sandy soil. • Scour depth has a stronger influence on the ultimate bearing capacity than the influences of scour width and angle. • Both the horizontal bearing capacity and the moment bearing capacity reach a plateau and a steady state manifest itself when the relative scour depth exceeds a threshold value of 0.9. • An empirical formulation to characterize the failure envelope within the horizontal force-moment (H-M) plane considering the effect of scour depth is proposed. Local scouring significantly undermines the load-bearing capacity of suction caisson foundations and poses a daunting challenge to the integrity of offshore structures. This study numerically addresses the impact that the size and shape of the local scour hole have on both the monotonic bearing capacities and failure envelopes of suction caisson embedded in sandy soil. Different loading conditions - individually and combined - by integrating local scour parameters such as scour depth (S d), scour width (S w) and scour angle (φ) while maintaining realistic scour proportions are carefully evaluated. The obtained results show that (1) scour depth has a stronger influence on the ultimate bearing capacity than the influences of scour width and angle; (2) the horizontal bearing capacity shows increased sensitivity to variations in scour depth; and (3) both the horizontal bearing capacity and the moment bearing capacity reach a plateau and a steady state manifest itself when the relative scour depth exceeds a threshold value of 0.9. An empirical formulation to characterize the failure envelope within the horizontal force-moment (H - M) plane is finally proposed, which properly considers the effect of scour depth. These findings provide a valuable reference for ensuring structural resilience to local scour phenomena. [ABSTRACT FROM AUTHOR]

Cyclic loading on caisson and pile anchors can be a significant design issue, particularly with respect to cumulative vertical displacements that can lead to reduction in embedment depth and load capacity of the anchor. Most existing design methodologies are based on monotonic load capacity, often accounting for potential soil strength degradation due to cyclic loading. Because the cyclic strength criterion is often based on cumulative strains, these approaches arguably implicitly consider cumulative deformations. However, cumulative plastic deformations under storm conditions should be investigated. Piles and caissons serving as anchors for floating offshore structures experience inclined cyclic loading. This paper presents (1) monotonic and cyclic loading tests in the vertical and lateral directions, and (2) a finite-element (FE) investigation of different aspect ratios (L/D=4 , 5, and 6) of caissons subjected to different load angles (ψ=0° to 45° from the horizontal). Additionally, it presents a precise method to calibrate the constitutive model (nonlinear kinematic hardening model), where the calibrated model was match to monotonic and cyclic lateral and vertical loading tests. Nonuniform load amplitudes were used in the FE investigation. The primary finding from the investigation was that the influence of the cumulative displacements increases when increasing the load amplitudes, especially for the load inclinations of 0°–20° for the lateral displacements and 20°–45° for the vertical displacements. [ABSTRACT FROM AUTHOR]

In the conventional caisson transportation and installation process, there are usually several workers working on the top of the caisson. The caisson is floating on the sea during transportation and installation. In case of emergency, workers cannot evacuate the caisson in time, which has potential safety hazards. Through the remote control research on the caisson water filling link, the remote control of water filling operation on the top of caisson is realized, and the measurement and control system accurately measures the water level and caisson posture, so as to ensure the safety of caisson water filling, and lay a foundation for the next step of realizing unmanned transportation and installation of caisson. [ABSTRACT FROM AUTHOR]

The uplift capacity factor of cylindrical suction caisson in anisotropic and inhomogeneous clays considering the adhesion factor at the interface is investigated in this paper. The finite element limit analysis based on lower bound and upper bound analyses is used for analyzing purposes. The anisotropic undrained shear model is employed to describe the anisotropic and inhomogeneous clay. The impact of these dimensionless parameters on the ratio of inhomogeneity or strength gradient ratio, the adhesion factor, the ratio of depth over diameter, and the ratio of anisotropic undrained shear strengths on the uplift resistance and the collapse mechanisms of suction caisson foundations are determined. The multivariate adaptive regression splines technique is employed to access the sensitivity of all considered dimensionless parameters on the uplift capacity factor and to propose an empirical design equation as an effective tool for predicting the uplift capacity factor. The results presented in this paper can be guidance for the preliminary design of suction caissons in anisotropic and non-homogeneous clays that are useful for engineering practitioners. [ABSTRACT FROM AUTHOR]

The stability of caisson type quay wall considering the displacements were investigated for two different cases: in the first case, cyclic loading with different frequency was applied to the caisson type quay wall and the horizontal displacement (damage) on the structure was measured then by repairing the damage due to cyclic loadings after each experiment, experiments were performed with different cyclic loadings in similar way, ii: in the second case, same cyclic loadings used in first case were applied on structure successively and without repairing the damages on structure and the displacement (damage) on the structure was measured. After completion of the experiments for two different cases, the measured displacements were compared. Based on the experiment results, it was seen that for same cyclic motion, displacements of the second case were less than those in the first case. In addition, using experimental results for the first case, the instantaneous dynamic friction coefficient between concrete and the gravel base was calculated. It was found that ratio between calculated instantaneous dynamic friction coefficient and static friction coefficient oscillates around 1. Displacements, calculated by using double integration of the relative acceleration, were in compatible with the measured displacements during the experiments. [ABSTRACT FROM AUTHOR]

Agreeing on the nominal resistance (aka. capacity) derived from any load-settlement curve requires the use of an interpretation criterion. Few of the currently available criteria have been originally designed for drilled foundations despite the increasing use of such piles for supporting infrastructure projects. The performance of 16 interpretation criteria used in current geotechnical practice was assessed using a database of 194 load tests conducted on drilled shafts. Their performance was evaluated in terms of: (1) applicability; (2) correlation among each other; and (3) the effect of drilled shaft diameter, length, and soil type. Eight of the 16 methods could not be reliably used. Capacities interpreted from the remaining eight were consistent but resulted in excessive settlement in a few cases. Performance was also evaluated in terms of serviceability. A new criterion is proposed, where the nominal resistance is defined as the load corresponding to the smallest of (1) a settlement equal to the elastic compression of a free-standing column plus 0.75 in. (20 mm); (2) the load at plunging or strain-softening; or (3) settlement corresponding to 5% of the pile diameter, unless modified by the structural engineer of record. The proposed method showed good correlation with several established criteria while including a built-in serviceability safeguard against excessive settlement. [ABSTRACT FROM AUTHOR]

Learning curves in construction operations analysis is deemed as one of the main factors that determine the variation of on-site productivity and is always taken into account during the planning and estimation stage. This research attempts the assessment of learning curve models’ suitability for the effective analysis of the learning phenomenon for construction operations that are fairly complicated concerning a floating caisson fabrication process for a large-scale marine project, using productivity data. This paper investigates the role of published learning curve models (i.e. Straight-line or Wright; Stanford "B"; Cubic; Piecewise or Stepwise; Exponential) by comparing their outcomes through the use of both unit and cumulative productivity data. There are two main research objectives: first, the model best fitting historical productivity data of construction activities that have been completed are investigated, while secondly, an attempt is made to determine which model better predicts future performance. The less actual construction data deviate from each model’s yielded results, the better their suitability. In the case of unit data, the cubic model fits better historical data, while in the case of future predictions, the Stanford “B” model provides better results. Respectively, the Cubic model yields better results when using cumulative data on historical data and the Straight-line model predicts in a more reliable fashion future performance Possible extensions could be developed in the area of future performance predictions, by adopting different data representation techniques (e.g. moving/exponential weighted average) or by including other (non-classic) learning curve models (e.g. DeJong, Knecht, hyperbolic models).

In the construction of Dalian Bay subsea tunnel, the structural forms of prefabricated and cast-in-situ immersed tubes, caissons, and breast walls are complex and diverse, and the size of structural section is large, the amount of formwork is huge. The traditional truss structure steel formwork structure has the problems of complicated design, high restructuring cost, long time-consuming, poor turnover versatility, difficult storage and maintenance and so on. A large combined steel formwork which is suitable for different structural construction was proposed and used. In the actual construction application, it is verified that it is convenient for installation, disassembly and combination, so as to meet the turnover use between various prefabricated and cast-in-situ concrete structures. [ABSTRACT FROM AUTHOR]

Abstract：The drainage pump house is used to drain water from the dock interior to the dock exterior, which is composed of drainage forebay, pump house caisson and breast wall, and is constructed by cast-in-situ construction method. The construction of drainage pump house is difficult due to its complex structure and high height. The construction sequence of layered cast-insitu drainage pump house and the construction technology of reinforcement, formwork and concrete were discussed in this paper. The implementation results show that the construction layer is reasonable, the operation is convenient, the efficiency is high, and the function and quality meet the design requirements. [ABSTRACT FROM AUTHOR]

Caissons are rigid foundations most commonly used to support bridge piers. In this study, numerical analysis using the finite-element method based computer program ABAQUS was carried out to study the response of caissons under static and pseudostatic conditions. The caisson was embedded in layered soil comprising a saturated clay layer sandwiched between two sand layers. Sand was modeled using an elastic, Mohr-Coulomb plastic model and clay was modeled using a porous elastic and clay plasticity model to account for soil consolidation. The wall friction angle (δ) and seismic acceleration coefficients (kh and kv) were varied in this study. Calculations were made by executing a mathematical code in MATLAB to obtain the lateral soil pressure, maximum and minimum base pressures, tilt, shift, and point of rotation of the caisson. The analysis was further extended to develop three-dimensional (3D) interaction diagrams relating the combination of applied vertical load (V), lateral load (Q), and moment (M) in nondimensional form required to cause caisson failure for different wall friction angles and seismic acceleration coefficients. These diagrams can be used for the safe design of caissons under different seismic conditions and ground conditions for a variety of design loads. [ABSTRACT FROM AUTHOR]

La antropología visual, como metodología de investigación, es válida en las ciencias sociales. Se destaca así, en este método, el proceso participativo y colaborativo devenido de la experiencia de trabajo etnográfico colectivo y audiovisual. Se desarrolla esta propuesta metodológica en el estudio de un caso concreto: los “pileros” afrodescendientes; obreros que trabajan en la construcción de pilas de cimentación, un oficio racializado, realizado por afrodescendientes de la ciudad de Medellín.

The round-ended caisson foundation has a promising application prospect in deep water foundation, but there are few researches on its hydrodynamic characteristics. Based on the foundation design of No.5 caisson of Changtai Changjiang Bridge, the three-dimensional numerical simulation of the flow field around the caisson in the sinking process was carried out using the large eddy simulation (LES) method. The calculation results show that the resistance coefficient of the side wall of the caisson is in good agreement with the experimental results. The velocity field distribution around the caisson is analyzed based on the time-averaged flow field, and it is found that the increase of the draught depth of a caisson leads to the increase of the lateral velocity on both sides of the caisson, and the decrease of the back flow velocity. The wake vortex structures in the caisson are captured and analyzed based on the transient flow field. This paper provides reference data for the selection of the method for caisson foundation sinking construction, reduces the development cycle and cost, and has practical engineering value. [ABSTRACT FROM AUTHOR]

Cumulative plastic deformations under cyclic loading can be a key consideration in the design of caissons and short piles. In the case of caissons and piles serving as anchors for floating offshore structures, the possibility of loss of embedment due to upward ratcheting of the anchor under cyclic loading is a particular concern. This paper presents a finite-element investigation of a caisson subjected to cyclic lateral and inclined loading. A cyclic hardening model is employed to permit simulation of cumulative plastic deformations during loading below the ultimate load state. An asymmetric Fourier analysis was employed as a highly efficient alternative to a full three-dimensional analysis, and results using the two approaches were found to be in good agreement. A realistic range of material parameters was established through back-analysis of laboratory model tests published previously. Parametric studies were performed to assess the effects of small-strain soil stiffness, subyield stress–strain behavior, load inclination, soil–pile interface adhesion, and load reversals. Pile performance for cyclic loading with nonuniform load amplitudes was also investigated. The aforementioned factors were found to have a moderate to large influence on the magnitude of cumulative displacements under cyclic loading. [ABSTRACT FROM AUTHOR]

The finite element analysis is conducted to study the causes of the failure of the caisson quay wall at Malaga Port Container Terminal in Spain. It was found that the marine clay lenses were the main reason for the accident because their low strength reduced the overall stability of the structure. The thickness of the marine clay lens increasing from 0 to 2.5 m decreases the factor of safety (FoS) from 1.288 to less than 1.0. The finite element analyses are also conducted to investigate the effects of dredging the marine clay lenses underneath the rubble mound and installing the vertical pipe piles on the stabilities of the caisson quay wall. The FoS increases nonlinearly with the increase of excavation depth of the marine clay lens underneath the rubble mound and the maximum magnitude is 1.267 when the excavation depth reaches ±29 m from the sea surface. Two lines of pipe pile installed in a square pattern with a spacing of 1.2 m and length of 23 m have an optimum distance to the caisson wall of 6 m to improve the FoS of the caisson quay wall with its maximum magnitude of 1.222. • The numerical analysis is conducted to study the caisson quay wall at Malaga Port Container Terminal. • Parametric studies are conducted to study the effect of the thickness and position of the marine clay lenses on the stability of the caisson quay wall. • Effects of dredging the marine clay lenses and installing the vertical pipe piles on the stabilities of the caisson quay wall are investigated. [ABSTRACT FROM AUTHOR]

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. • Underwater explosion test in free field and on RC caisson specimen was conducted. • Overpressure-time histories including blast wave and bubble pulsation were recorded. • Reflection coefficient of underwater blast wave on structure is determined around 1.7 • FE approach to predict overpressures and structural dynamic behaviors was validated. [ABSTRACT FROM AUTHOR]

Floating caissons may oscillate primarily due to ocean waves during towing operations. Reducing the oscillation based on the extension part (footing) of the bottom slab of the caissons can efficiently increase the safety of towing maneuvers. However, the influence of the footing length on the motion of floating caissons has not been adequately studied. This study investigates this topic through hydraulic model experiments and numerical simulations. Experimental results for regular waves show that the rotational motion (pitch) of the caisson around the wave crest direction increases owing to resonance. This suggests that the pitch could be reduced by designing caissons, such that resonance may be prevented along the footing length. In the numerical simulations of irregular waves, the Fourier amplitudes of the heave and pitch show that the footings amplify their low-frequency components and reduce their high-frequency components. Furthermore, the significant total amplitudes of the heave and pitch show a different trend from that of the regular waves observed in the hydraulic model experiments. This suggests that it is essential to examine the motion of a caisson under irregular waves when assessing the effect of footings in an actual marine environment.