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Seismic stability of gravity-type quay walls and prevention of their large distortion are of major concern
from a disaster prevention view point as well as in the sense of successful restoration after strong seismic
events. There are, however, many existing walls which are of limited seismic resistance and would not
be safe under increasing magnitu...
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Context 1
... models were constructed by using Toyoura sand which was of around 40% relative density (Figure 20). Figure 21 shows the side view of the model without mitigation before the test. Figure 22 shows the same model after the shaking. ...
Context 2
... displacement of the soil was measured by both displacement transducers at relevant locations and by taking pictures of coloured sand markers embedded in the model. Figure 23 was produced by superimposing Figure 21 and Figure 22 to clearly show the distortion of the model caused by the shaking. ...
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Citations
... Such deformations include slip surface failure, sliding, overturning and over stresses at the structure foundation [3-7, 19, 22, 23]. The typical failure modes of gravity quay walls due to seismic loads on either loose or stiff soil include tilting and seaward horizontal displacements [31,32,[34][35][36][37]42]. ...
This study explores the seismic performance of a prototype block-type quay wall using the PLAXIS 2D software. The numerical model was forced by historical records of two earthquakes employing four soil types including sand, clay, gravel, and rock. The study investigated the influence of the earthquake seismic motion level, seismic motion configuration, peak ground acceleration (PGA) value, tidal range, and soil type on the structure behavior under the seismic action. Additionally, assessing the accepted damage level of the structure based on the computed horizontal displacement and tilting. Results indicate that the structure behaves differently under the same seismic load conditions when changing the soil type. Larger horizontal displacements are found below the rubble base for the sandy soil case in comparison with gravel and rocky soils. Moreover, the seismic motion configuration significantly affects the structure behavior even when the PGA is unchanged. The structure is significantly affected by the seismic action when it starts suddenly with a strong acceleration during the first seconds of the earthquake when the soil is sand. However, the contrary behavior occurs for gravel and rocky soils. Results also indicate that changing the seismic motion level and the tidal range have a minor impact on the structure behavior. The most critical section is located at the toe of the rubble base. Results show that the worst and best performances of the structure are obtained with sand and gravel soils, respectively. In most conditions, a controlled damage was obtained with a tilting< 1.5˚ and a normalized horizontal displacement <5% for PGA values< 0.5 g. Otherwise, failures would take place due to the seaward displacement of the quay wall structure.
... Experimental modal experiments were performed in a test tank with inside dimensions of 1000 mm long, 600 mm wide, and 600 mm high. To ensure that the failure wedge around the wall was not affected by the walls, these dimensions were chosen from the study done by Towhata, Alam [10]. Figure 1 shows a schematic view of the experimental apparatus. ...
Dredging is usually used in constructing the buildings' basements and causing large failures in the existing retaining walls. This study is about the behavior of retaining walls as a result of bed dredging through many experimental tests. The dredging system has been performed by using a suction system via vacuum air. This study was carried out by varying the ratio of the dredging depth to wall width (Y/B w), the ratio of the distance from the bed of wall to wall width (b/B w), the slope of dredging, live load acts on the top of retaining wall, and the relative density of sand (D r). The ultimate live load lowered by about 34.14, 24.26, 23.16, 13.28 and 1.21% with varying the ratio of the distance from the bed of wall to wall width (b/B w) of 0.25,0.50,1.00,1.50 and 2.00, respectively, at constant values of slope 2H:1V, Y/B w = 1/3 and D r = 50%. However, at D r = 80%, it becomes 32.36, 18.39, 17.65, 8.00 and 0.74%, over that without dredging case. The results showed that the relative density and the distance from the bed of the wall have a significant effect on the wall's stability as aresult of dredging the bed.
... The input motion used in numerical modeling having an amplitude 0.8g with duration 10 sec as shown in the figure 3, which represents twice the magnitude of Tokachi Oki, Japan in 2003 earthquake and pam, Iran in 2002 [17]. This destructive magnitude is selected to simulate the input motion of shaking table tests that were performed by [16] to see how the numerical will verify the experimental results. ...
... The forms of failure were seen in many previous studies, as well as in the sites of ports and man-made islands after the earthquakes were slipping, reversal, deep slipping, and failure of the foundation. So, the stability calculations of the quay wall structure revolve around several important things, which are settlement, carrying capacity of the foundation, slipping and overturning [13]. The port quay walls are designed at a certain seismic motion boundary. ...
... The forms of failure were seen in many previous studies, as well as in the sites of ports and man-made islands after the earthquakes were slipping, reversal, deep slipping, and failure of the foundation. So, the stability calculations of the quay wall structure revolve around several important things, which are settlement, carrying capacity of the foundation, slipping and overturning [13]. The port quay walls are designed at a certain seismic motion boundary. ...
Earthquakes are one of the worst natural disasters that effect directly both human life and infrastructures around the world. The seismic behavior of a gravity quay wall has been outlined from art-of-literature in this review paper. Based on previous studies available on the subject, the paper includes a simplified introduction of gravity quay walls structures followed by the loads acting on the quay wall which are used in the design, modes of failure, forces generated during earthquakes, method of evaluation of displacement of gravity quay wall and the techniques that used to reduce the damage caused by liquefaction during earthquakes. Through the discussion, it was concluded that when shaking amplitude is high at low frequency and the soil of the foundation underneath the quay wall is loose, an increases in the distortion of the wall is noticed. Pore water pressure increasing in the soil and backfill soil leads to an increase in the amount of deformation twice the case of constant pore water pressure. The sliding of the caisson is greatly increased when liquefaction occurs in the backfill soil and the different used techniques to reduce the liquefaction damage during the earthquake had good results in several locations.
... The input motion used in numerical modeling having an amplitude 0.8g with duration 10 sec as shown in the figure 3, which represents twice the magnitude of Tokachi Oki, Japan in 2003 earthquake and pam, Iran in 2002 [17]. This destructive magnitude is selected to simulate the input motion of shaking table tests that were performed by [16] to see how the numerical will verify the experimental results. ...
The main important factor that has to be considered by the designers during the preliminarily design stage of quay walls in ports is uunderstanding the mechanism of the damages that occurs during earthquakes. Increasing of seismic disasters occurrence during recent decades leads to increase the attention during this stage. For this purpose, Finite element modeling is performed to investigate the seismic performance of gravity quay wall (caisson). Plaxis 2D software is used to simulate seismic behavior of real gravity quay wall (i.e. Kobe harbor quay wall) using single frequency earthquake motion. The response of the acceleration and the seismic displacement of the quay wall are simulated. The shaking table tests of two models of the quay wall in dry and saturated conditions were compared with the results of numerical modeling. The results showed that the seismic wave amplification is increased significantly from the foundation of the gravity quay wall to the surface of the model, in which the highest amplification happened at the top of the quay wall model. It was observed that the Plaxis-2d finite element models is an effective tool to predict the seismic performance of the quay wall and there was clear agreement between both the results of experimental results and numerical modeling.
... Extensive studies have been conducted on the seismic performance of caisson-type gravity quay walls, including 1 g and centrifuge model tests [7][8][9]15,[17][18][19][20][21][22][23][24][25][26], analytical analyses [16,[27][28][29][30][31][32][33][34], and numerical simulations [35][36][37][38][39][40][41][42][43][44], especially after the 1995 Kobe earthquake and the 2011 Tohoku earthquake [45]. However, investigations into the response of block-type quay walls, which are often the most commonly used type of quay wall [46], under seismic loading are relatively limited. ...
Block-type gravity quay walls are widely used in remote oceanic regions due to their cost and construction efficiency , where backfill and foundation soil often consist of liquefiable calcareous coral sand. The lack of connection between blocks and hence structure integrity can result in poor seismic performance of block-type quay walls, especially in liquefiable soil. Based on laboratory element tests on calcareous sand, centrifuge shaking table test, and high-fidelity numerical simulation, this paper investigates the seismic performance of block-type quay walls with liquefiable calcareous sand backfill. Undrained cyclic torsional shear tests are conducted on South China Sea calcareous coral sand to determine its dynamic properties, which are used to calibrate the unified plasticity model for large post-liquefaction shear deformation of sand. A centrifuge shaking table test is conducted to obtain the basic physical seismic response of a block-type quay wall in liquefiable calcareous backfill sand. Utilizing the understanding from laboratory tests, fully coupled dynamic effective stress analysis using the calibrated constitutive model is conducted. The influence of seismic input, quay wall structure, and backfill sand properties on the seismic response of the quay wall is analyzed. Input motion intensity and frequency are shown to be influential to the seismic response of the quay wall. Increase of backfill soil density, permeability, and block to block connection can significantly improve the seismic performance of the quay wall.
... Since, at the time of the earthquake, one can assume that the displacement above the retaining wall is equal to the movement of the bottom of the berth, i.e., the same level of the sea bed, then, we did not consider a degree of freedom of the retaining wall in the model in this research to evaluate the different retaining walls with different dynamic behaviors. However, its effects were regarded somehow due to this wide range of periodicity of the structure although this assumption has been reasonable in the laboratory observations of Towhata et al. [31]. The structure of the wharf is in interaction with the soil. ...
One of the most important structures in the ports is the wharf. The most common one is the pile-supported wharf. This type of wharf is consisted of a number of piles and one deck which placed on the piles. In addition to the conventional loads that this structure should withstand, in seismic areas, pile-supported wharfs should have the necessary capacity and strength against seismic excitations. There are some approaches to increase the seismic capacity of the berth. One of these methods is to control the vibrations of the pile-supported wharf against earthquake loads using a damper. In this research, for the first time, a new semi-active damper called the semi active liquid column gas damper (SALCGD), was used to reduce the response of pile supported wharf under seismic loads. In the first step by applying different records of the earthquake, the most important parameter of this damper - the optimal opening ratio of the horizontal column- was obtained for this particular structure. In the following, the performances of this damper and its comparison with the tuned liquid column gas damper (TLCGD) were discussed. This study showed that the use of this semi-active damper (SALCGD) reduces the displacement of the pile-supported wharf by 35% and reduces the acceleration of the structure by 50% on average. In contrast, the passive damper (TLCGD) reduces the displacement of about 20 percent and the acceleration of about 30 percent. Therefore, it was observed that the semi-activation of the damper (SALCGD) had a significant improvement in its performance in controlling the vibrations of pile-supported wharf.
... Experimental and/or analytical studies by Miura et al. [9], Fujiwara et al. [3], Mohajeri et al. [10], Mendez et al. [8] and Nakahara et al. [11] were presented to assess the dynamic response of gravity type quay walls. Additionally, Inoue et al. [5], Kim et al. [7], Kim et al. [6], Towhata et al. [16] and Yuksel et al. [18] approached the problem through experimental and/or numerical approaches. There exist also purely numerical studies performed by Alyami et al. [1], Arablouei et al. [2] and Tiznado and Rodriguez-Roa [15]. ...
The preceding companion paper presented the updating of the seismic soil liquefaction triggering relationship of
Cetin et al. [1], and compared the resulting updated relationship with the earlier version. In this second paper, a
detailed cross-comparison is made between three triggering relationships: (1) Seed et al. [2], as slightly updated
by the NCEER Working Group (Youd et al. [3]), (2) Boulanger and Idriss [4], and (3) Cetin et al. [5]. Differences
between these three triggering relationships, and the apparent causes of them are examined. Also studied are the
impacts of these differences on levels of conservatism with regard to evaluation of liquefaction triggering hazard,
and the resulting risks for engineering projects.
... The floor of the container was covered with a fine-sieve mesh (sieve No. 200) so that the saturation process could be done gradually and uniformly. The mentioned method has been used before by other researchers (Towhata et al., 2009) in physical modeling tests. Note: G s is the specific gravity, c is the cohesion, f is the internal friction angle, D 50 is the average size of sand grains, and K is the hydraulic conductivity. ...
Liquefaction is one of the most destructive natural hazards that cause damage to engineering structures during an earthquake. This study aims to examine the effect of rubber and gravel drainage columns on the reduction of liquefaction potential of saturated sandy soils using a shaking table. Experiments were carried out in various conditions such as construction materials, different arrangements and diameters of drainage columns. Effects of the relative density and the input motion on the base test were investigated as well. The results demonstrate that rubber drainage columns have slightly better performance compared to gravel drainage columns at high relative density and high input acceleration. Soil improvement using gravel drainage columns, which leads to reduction in liquefaction effects at moderate input acceleration and low relative density, is a more effective method than that using rubber drainage columns. By increasing the number and diameter of gravel and rubber drainage columns, deformations due to liquefaction are reduced. The drainage rate of gravel drains is higher than that of rubber drains after shaking. Totally, the outcomes indicate that densification is the most important factor controlling liquefaction. © 2018 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences
