scholarly journals Effect of Seismic Loading on Variation of Pore Water Pressure During Pile Pull-Out Tests in Sandy Soils

2021 ◽  
Vol 27 (12) ◽  
pp. 1-12
Author(s):  
Haider N. Abdul Hussein ◽  
Qassun S. Mohammed Shafiqu ◽  
Zeyad S. M. Khaled
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Seismic Loading ◽  
Shaking Table ◽  
Dense Sand ◽  
Pressure Transducers ◽  
Pull Out ◽  
Pullout Tests ◽  
Pile Model

Experimental model was done for pile model of L / D = 25 installed into a laminar shear box contains different saturation soil densities (loose and dense sand) to evaluate the variation of pore water pressure before and after apply seismic loading. Two pore water pressure transducers placed at position near the middle and bottom of pile model to evaluate the pore water pressure during pullout tests. Seismic loading applied by uniaxial shaking table device, while the pullout tests were conducted through pullout device. The results of changing pore water pressure showed that the variation of pore water pressure near the bottom of pile is more than variation near the middle of pile in all tests. The variation of pore water pressure after apply seismic loading is more than the variation before apply seismic loading near the middle of pile and near the bottom of pile and in loose and dense sand. Variation of pore water pressure after apply seismic loading and uplift force is less than the variation after apply seismic loading in loose sand at middle and bottom of pile.

scholarly journals Numerical Evaluation of The Nonlinear Behavior of Soil-Pile Interaction Under The Effect of Coupled Static-Dynamic Loads

2021 ◽  
Author(s):  
Duaa Al-Jeznawi ◽  
ISMACAHYADI Mohamed Jais ◽  
Bushra S. Albusoda
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Three Dimensional ◽  
Ground Surface ◽  
Frictional Resistance ◽  
Saturated Soil ◽  
Shaking Table ◽  
Physical Models ◽  
Soil Layers

Abstract Liquefaction of saturated soil layers is one of the most common causes of structural failure during earthquakes. Liquefaction occurs as a result of increasing pore water pressure, whereby the rise in water pressure occurs due to unexpected change in stress state under short-term loading, i.e., shaking during an earthquake. Thus, general failure occurs when the soil softens and eliminates its stiffness against the uplift pressure from the stability of the subsurface structure. In this case, the condition of soil strata is considered undrained because there is not enough time for the excess pore water pressure to dissipate when a sudden load is applied. To represent the non-linear characteristics of saturated sand under seismic motions in Kobe and Ali Algharbi earthquakes, the computational model was simulated using the UBCSAND model. The current study was carried out by adopting three-dimensional-based finite element models that were evaluated by shaking table tests of a single pile model erected in the saturated soil layers. The experimental data were utilized to estimate the liquefaction and seismicity of soil deposits. According to the results obtained from the physical models and simulations, this proposed model accurately simulates the liquefaction phenomenon and soil-pile response. However, there are some differences between the experiment and the computational analyses. Nonetheless, the results showed good agreement with the general trend in terms of deformation, acceleration, and liquefaction ratio. Moreover, the displacement of liquefied soil around the pile was captured by the directions of vectors generated by numerical analysis, which resembled a worldwide circular flow pattern. The results revealed that during the dynamic excitation, increased pore water pressure and subsequent liquefaction caused a significant reduction in pile frictional resistance. Despite this, positive frictional resistance was noticed through the loose sand layer (near the ground surface) until the soil softened completely. It is worth mentioning that the pile exhibited excessive settlement which may attribute to the considerable reduction, in the end, bearing forces which in turn mobilizing extra end resistance.

Numerical simulations of seismic and post-seismic behavior of tailings

2016 ◽  
Vol 53 (1) ◽  
pp. 85-92 ◽  
Author(s):  
Behnam Ferdosi ◽  
Michael James ◽  
Michel Aubertin
Keyword(s):  
Pore Water ◽  
Simple Shear ◽  
Seismic Behavior ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Shaking Table ◽  
Shear Testing ◽  
Cyclic Shear ◽  
Main Components ◽  
Excess Pore

Several tailings impoundments have failed as a result of earthquakes in the last few decades. A majority of these failures were due to direct seismic loading, tailings liquefaction during shaking, or the post-seismic behavior of the tailings as it relates to the dissipation of excess pore-water pressures that were generated during shaking. Previous work has indicated that the UBCSAND model developed by Byrne et al. in 1995 is capable of simulating the cyclic simple shear testing response of low-plasticity tailings over a range of consolidation stresses and cyclic shear ratios. However, the ability of the model to simulate the dynamic and subsequent behavior of such tailings for other conditions, such those induced by shaking table tests, has not yet been evaluated. In this regard, previous work has shown that the main components of the UBCSAND model cannot realistically simulate some specific responses, including the post-seismic volumetric strains related to excess pore-water pressure dissipation. This paper presents numerical modeling results of the dynamic behavior of tailings from hard rock mines. It introduces a method for simulating their post-seismic behavior by including an updating scheme for the elastic moduli into the UBCSAND model. The results of cyclic simple shear testing, seismic table testing, and complementary experimental relationships were used to calibrate and validate the model with its new component. The simulated response of tailings during cyclic simple shear testing and for a complete seismic table test shows that the proposed approach simulates the experimental observations well. Level-ground, seismically induced liquefaction and post-seismic behavior of a 15 m thick tailings deposit are also simulated, leading to post-liquefaction settlements that are in agreement with empirical relationships.

Softening of the Clayey Seabed Foundation due to Earthquakes

1988 ◽  
Vol 110 (1) ◽  
pp. 17-23 ◽  
Author(s):  
N. Mori ◽  
Y. Ishikawa ◽  
A. Hirayama ◽  
K. Tamaoki ◽  
H. Kobayashi
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Confining Pressure ◽  
Offshore Structures ◽  
Model Tests ◽  
Shaking Table ◽  
Earthquake Response ◽  
Response Analysis ◽  
Earthquake Response Analysis

Offshore structures are subjected to repeated loads from earthquakes and waves which may cause softening of the clayey seabed foundation. Carrying out a series of model tests on a shaking table, the following results are obtained. Settlement and inclination of a model of the base-part of the structure occur when the excess pore water pressure beneath the model rises to about 5 percent of the initial confining pressure. The earthquake response analysis even taking the nonlinearity of the soil into account cannot predict the results of the model test when the pore water pressure does generate and accumulate. Model tests show that the values of the pore water pressure are about twice as large as those predicted by calculation. From these results, rough evaluation of earthquake stability of the clayey seabed under offshore structures are obtained.

Laboratory calibration of pressure transducer-tensiometer system for hydraulic studies

1994 ◽  
Vol 74 (3) ◽  
pp. 315-319 ◽  
Author(s):  
R. H. Azooz ◽  
M. A. Arshad
Keyword(s):  
Pore Water ◽  
Pressure Transducer ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Hydraulic Gradient ◽  
Gradient Distribution ◽  
Pressure Transducers ◽  
Soil Pore Water ◽  
Laboratory Calibration ◽  
Influence Of Temperature On

Pressure transducer-tensiometer (PTT) systems can be used to continuously monitor soil pore water pressure and the hydraulic gradient distribution in a field, and under laboratory conditions over relatively short time intervals. A reliable laboratory calibration of a PTT system can determine the effects of temperature fluctuations on output readings in the field. Laboratory calibrations of 20 PTTs were conducted under constant pressures of 0, − 25, − 50 and − 75 kPa and constant temperatures of 5, 15, 25 and 48 °C. Twenty Bourdon gauge tensiometers (BGTs) and pressure transducers (PTs) were also calibrated to check changes in the sensitivity and effectiveness of the PTT system, when the Bourdon gauge of the tensiometer is replaced by a PT. Readings of all the three systems revealed that pressure values gradually declined with an increase in temperature. With a temperature change from 5 to 48 °C, the pressure values at constant pressures of 0, − 25, − 50 and − 75 kPa decreased by 0, 3.7, 4.1 and 4.5 kPa for the BGT; 2.05, 2.16, 2.23 and 2.44 kPa for PT and 2.53, 2.87, 2.88 and 3.17 kPa for PTT. As the influence of temperature on the calibration curve of the PTT and PT systems was different, it is recommended that the complete PTT system should be calibrated in the laboratory to adjust the output readings to the anticipated temperature in the field. Key words: Tensiometer, tensiometer-pressure transducer, soil pore water pressure, hydraulic gradient

Shaking table tests to parametrically evaluate post-shaking settlements and pore water pressure build-up in marine sands

2021 ◽  
Vol 14 (8) ◽  
Author(s):  
Ali Ghorbani ◽  
Afshar Nemati Mersa ◽  
Mehdi Veiskarami ◽  
Naser Hamidzadeh ◽  
Hadi Hasanzadehshooiili
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Shaking Table ◽  
Shaking Table Tests

scholarly journals Dynamic response of thickened tailings in shaking table testing

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Fahad Alshawmar ◽  
Mamadou Fall
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Bottom Layer ◽  
Vertical Displacement ◽  
Thin Layers ◽  
Shaking Table ◽  
Water Migration ◽  
Shaking Table Testing ◽  
Thickened Tailings

AbstractIn this study, an instrumented thickened tailings deposit model was designed, built and employed to evaluate the behaviour of layered thickened tailings to dynamic loading by using a shaking table equipment. The thickened tailings were deposited subsequently in three thin layers in a flexible laminar shear box mounted on top of the shaking table. Cyclic loading with a peak horizontal acceleration of 0.13 g and a frequency of 1 Hz was applied to the layered tailings deposit. Different types of sensors were placed to monitor the accelerations, displacements, volumetric water content and pore water pressures at the intermediate depth of each layer. Results indicated that the acceleration for the bottom and middle layers were similar to that of the base of the shaking table; but, this was not the case for the top layer. The measurements of vertical displacements indicated that all layers of thickened tailings experienced initially contraction and subsequently dilation during the shaking. The excess pore water pressure ratios were found to exceed unity through all layers of thickened tailings when the shaking ended. In other words, the results showed that the layered thickened tailings are susceptible to liquefaction under the considered testing conditions. It is also found that upward pore water migration to the top layer and downward pore water flow to the bottom layer occurred in the thickened tailings deposit. This water migration generated additional pore water pressure and also impacted the vertical displacement and liquefaction susceptibility of the thickened tailings material. The results of this study give a better understanding of the dynamic behaviour of thickened tailings, which is crucial for the safety of thickened tailings systems as well as sustainable mining.

Primary Study on Mechanism of Earthquake-Induced Differential Settlement of Buildings on Liquefiable Subsoil

2012 ◽  
Vol 594-597 ◽  
pp. 352-357
Author(s):  
Fan Chao Meng ◽  
Xiao Ming Yuan ◽  
Hui Xue
Keyword(s):  
Pore Water ◽  
Dynamic Stress ◽  
Shaking Table Test ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Time History ◽  
Decisive Role ◽  
Sine Wave ◽  
Shaking Table ◽  
Primary Study

The shaking table test on liquefied soil - structure interaction was desighed. In the test, the building model and the soil were evenly arranged, after being put horizontal sine wave acceleration time history, building symmetrical basal dynamic stress, pore water pressure and earthquake-induced settlement time history were obtained. The results are: (1) symmetrical basal vertical dynamic stress, pore water pressure, earthquake-induced settlement reaction time history appeared antisymmetric distribution; (2) basal dynamic stress is controlled by the input waveform, the basal vertical dynamic stress plays a decisive role in the increase of the pore water pressure, while difference of pore water pressure decides difference of earthquake-induced settlement, which causes the building tilts toward the direction of higher pore water pressure; (3) a correlation exists among input wave, basal vertical dynamic stress, pore water pressure and structural earthquake-induced settlement. The mechanism of earthquake-induced settlement is: acceleration waveform  form of both sides basal dynamic stress cumulative form of both sides basal pore pressure form of earthquake-induced settlement.

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