scholarly journals Evaluation on Influences of Inertial Mass on Seismic Responses and Structure-soil Interactions of Pile-soil-piers

2021 ◽  
Author(s):  
Wen XIE ◽  
Limin Sun ◽  
Tiantao He
Keyword(s):  
Bending Moment ◽  
Inertial Mass ◽  
Pile Group ◽  
Interaction Effects ◽  
Scale Model ◽  
Seismic Responses ◽  
Configuration Change ◽  
Inertial Interaction ◽  
Shear Box ◽  
Group Effects

Abstract This research is to assess the influences of the inertial mass from the girder on the dynamic characteristic, dynamic response, and structure-soil interaction of a pile-soil-pier subsystem in a scale-model of a cable-stayed bridge. Therefore, both connection configurations between the pile-soil-pier and girder, including the sliding and fixed connections, were designed to present various inertial mass from the superstructure delivered to the pile-soil-pier. The pile-soil-pier supported by a 3×3 pile-group in mixed soil placed in a shear box was tested using shaking tables. The dynamic characteristics, seismic responses, inertial interactions, and pile group effects of the pile-soil-pier between the sliding and fixed connections were analyzed under three input motions with different shaking amplitudes. These results showed that more inertial mass from the girder significantly increased the reinforcement strain and bending moment at the column bottom and pile top, displacement at the column top, inertial interaction effects, and pile group effects of the pile-soil-pier due to the sliding connection changing to the fixed connection. The inertial mass increment from the girder noticeably decreased the peak accelerations of the column of the pile-soil-pier when subjected to three input motions with different amplitudes. However, the inertial mass insignificantly affected the accelerations of the pile and free-soil. Therefore, the corresponding kinematic interaction effects were almost unaffected by the inertial mass. Additionally, the evident pile group effects were observed in the sliding and fixed connections between the pile-soil-pier and girder. 24 The numerical model could approximately reproduce the macroscopic seismic responses of the pile-soil-piers with sliding and fixed connections and capture the typical response variations induced by the connection configuration change.

Seismic Response of Pile Groups Improved with Deep Cement mixing Columns in Liquefiable Sand: Shaking Table Tests

2021 ◽  
Author(s):  
Dingwen Zhang ◽  
Anhui Wang ◽  
Xuanming Ding
Keyword(s):  
Seismic Behavior ◽  
Lateral Displacement ◽  
Bending Moment ◽  
Pile Group ◽  
Shaking Table ◽  
Excess Pore Pressure ◽  
Shaking Table Tests ◽  
Pile Groups ◽  
Acceleration Response ◽  
Table Model

A series of shaking table model tests were performed to examine the effects of deep cement mixing (DCM) columns with different reinforcement depths on the seismic behavior of a pile group in liquefiable sand. Due to the DCM column reinforcement, the fundamental natural frequency of the model ground increases noticeably. The excess pore pressure of soils reduces with the increase of reinforcement depths of the DCM columns. Before liquefaction, the acceleration response of soils in the improved cases is obviously lower than that in the unimproved case, but the acceleration attenuation is greater after liquefaction in the unimproved case. Moreover, the lateral displacement of the superstructure, the settlement of the raft, and the bending moment of the piles in the improved cases are significantly reduced compared to those in the unimproved case, and the reduction ratios rise with the increase of reinforcement depth of the DCM columns. However, reinforcement by the DCM columns may result in the variation of the location of the maximum moment that occurs in the pile.

scholarly journals Comparison of Induced Deflection and Forces in Piles Adjacent to Tunnelling and Deep Excavation in 2D and 3D Problems

2018 ◽  
Vol 203 ◽  
pp. 04011
Author(s):  
Ong Yin Hoe ◽  
Hisham Mohamad
Keyword(s):  
Bending Moment ◽  
Pile Group ◽  
3D Models ◽  
Deep Excavation ◽  
Pile Groups ◽  
Out Of Plane ◽  
National University ◽  
Plane Direction ◽  
2D And 3D ◽  
2D Model

There is a trend in Malaysia and Singapore, engineers tend to model the effect of TBM tunneling or deep excavation to the adjacent piles in 2D model. In the 2D model, the pile is modelled using embedded row pile element which is a 1-D element. The user is allowed to input the pile spacing in out-of-plane direction. This gives an impression to engineers the embedded pile row element is able to model the pile which virtually is a 3D problem. It is reported by Sluis (2014) that the application of embedded pile row element is limited to 8D of pile length. It is also reported that the 2D model overestimates the axial load in pile and the shear force and bending moment at pile top and it is not realistic in comparison to 3D model. In this paper, the centrifuge results of single pile and 6-pile group - tunneling problem carried out in NUS (National University of Singapore) are back-analysed with Midas GTS 3D and a 2D program. In a separate case study, pile groups adjacent to a deep excavation is modelled by 3D and 2D program. This paper compares the deflection and forces in piles in 2D and 3D models.

scholarly journals An Experimental Study of Horizontal Bearing Capacity of Vertical Steel Floral Tube Micropiles with Double Grouting

2018 ◽  
Vol 2018 ◽  
pp. 1-11
Author(s):  
Kaiyang Wang ◽  
Yanjun Shang
Keyword(s):  
Bearing Capacity ◽  
Large Scale ◽  
Slip Surface ◽  
Bending Moment ◽  
Shear Capacity ◽  
Soil Reinforcement ◽  
Scale Model ◽  
Soil Pressure ◽  
Floral Tube ◽  
Grouting Pressure

This paper examines the performance of a novel technology, vertical steel floral tube micropiles with double grouting. It is the combination of micropile technology and double grouting technology. A large-scale model tank was applied to impart horizontal bearing capacity, and the slope soil pressure and flexural performance of the micropile were investigated under four experimental conditions. The peak grouting pressure during the double grouting process was defined as the fracturing pressure of the double grouting, and it was positively correlated to the interval time between first grouting and secondary grouting. Compared with traditional grouting, double grouting increased the horizontal bearing capacity of the single micropile with the vertical steel floral tube by 24.42%. The horizontal bearing capacity was also 20.25% higher for the structure with three micropiles, compared with a 3-fold value of horizontal sliding resistance. In the test, the maximum bending moment acting on the pile above the sliding surface was located 2.0–2.5 m away from the pile top, and the largest negative bending moment acting on the pile below the slip surface was located 4.0 m away from the pile top. The ultimate bending moment of the single pile increased by 12.8 kN·m with double grouting, and the bending resistance increased by 96.2%. The experimental results showed that the double grouting technology significantly improved the horizontal bearing capacity of the micropile with the steel floral tube, and the soil reinforcement performance between piles was more pronounced. Also, the shear capacity and the flexural capacity were significantly improved compared with the original technology.

Effect of Existing Building Walls on the Geotechnical Behavior of Foundation under Earthquake Loading

2021 ◽  
Vol 6 (4) ◽  
pp. 100-104
Author(s):  
M. N. Massoud Elsiragy
Keyword(s):  
Large Scale ◽  
Bending Moment ◽  
Horizontal Displacement ◽  
Scale Model ◽  
Earthquake Loading ◽  
Three Dimensional Model ◽  
Foundation Soil ◽  
Soil System ◽  
Existing Building ◽  
Building Walls

— Structure’s systems are subjected to additional loads due to earthquakes that may be produces progressive failures. The building illustrates dissimilar categories of failure mechanism for the minor to major earthquake conditions. These structures categorized to the most susceptible type of building has experienced serious hazard or even full failure for the period of seismic activities, therefore their investigation is a complex thing to do. Consequently, this research aims at studying the behaviour of large-scale model of structures constructed with and without brick walls under seismic conditions. The effect of building walls on the performance of the structure during earthquake loading is investigated numerically using PLAXIS 3D software. An eight story building with basement designed on a mat foundation is simulated as three-dimensional model in case of brick walls existing and without brick walls case. The effect of existence such wall building on the stability of foundation soil system is discussed in the form of lateral, horizontal deformation, and foundation acceleration. The studied showed that the reduction of extreme horizontal displacement and bending moment for building foundation with brick walls reached to 43%, and 68% respectively compared to the building without walls. The consideration of wall as filling for super structure significantly reduce the foundation acceleration by as much as 72% of its initial value, which lead to considerable effect of increasing the foundation stability.

scholarly journals Influence of the phase difference between kinematic and inertial loads on seismic behaviour of pile foundations in layered soils

2020 ◽  
Author(s):  
Thejesh Kumar Garala ◽  
Gopal Madabhushi
Keyword(s):  
Natural Frequency ◽  
Free Field ◽  
Phase Relationship ◽  
Phase Variation ◽  
Bending Moment ◽  
Pile Group ◽  
Pile Foundations ◽  
Single Pile ◽  
Seismic Behaviour ◽  
Soil Layers

A series of dynamic centrifuge experiments was conducted on model pile foundations embedded in a two-layered soil profile consisted of soft-clay layer underlain by dense sand. These experiments were specifically designed to investigate the individual effect of kinematic and inertial loads on a single pile and a 3×1 row pile group during model earthquakes. It was observed that the ratio of free-field soil natural frequency to the natural frequency of structure might not govern the phase relationship between the kinematic and inertial loads for pile foundations as reported in some previous research. The phase relationship obtained in this study agrees well with the conventional phase variation between the force and displacement of a viscously damped simple oscillator subjected to a harmonic force. Further, as expected, the pile accelerations and bending moments can be smaller when the kinematic and inertial loads act against each other compared to the case when they act together on the pile foundations. This study also revealed that the peak kinematic pile bending moment will be at the interface of soil layers for both single pile and pile group. However, in the presence of both kinematic and inertial loads, the peak pile bending moment can occur either at the shallower depths or at the interface of soil layers depending on the pile cap rotational constraint.

Dynamic Behavior of Submarine Pipelines Under Laying Operation

1982 ◽  
Vol 104 (4) ◽  
pp. 313-318 ◽  
Author(s):  
N. Suzuki ◽  
N. Jingu
Keyword(s):  
Experimental Study ◽  
Dynamic Behavior ◽  
Water Depth ◽  
Forced Oscillation ◽  
Bending Moment ◽  
Scale Model ◽  
Regular Waves ◽  
Wave Response ◽  
Dynamic Bending

Theoretical and experimental study on dynamic behavior of submarine pipelines under laying operation with articulated stingers is described in this paper. Wave response tests in regular waves and forced oscillation tests in still water were conducted using the 1/20 scale model of 406.4 mm o.d. (16 in. o.d.) pipeline laid in 150 m (500 ft) water depth. The results show that: 1) the maximum dynamic bending moment of pipeline MDmax occur at a stinger roller, 2) dynamic bending moment of pipelines MD at shorter periods are larger than those at longer periods, 3) the values of MD in an over-bend region depend highly upon stinger motion, 4) those of MD in a sag-bend region are less than MD max in an over-bend region, 5) the values of MD/HMY increase as the stinger volume increases and that 6) stinger motion at shorter periods are different from those at longer periods.

Interaction effects on load-carrying behavior of piled rafts embedded in clay from centrifuge tests

2015 ◽  
Vol 52 (10) ◽  
pp. 1550-1561 ◽  
Author(s):  
Donggyu Park ◽  
Junhwan Lee
Keyword(s):  
Pile Group ◽  
Interaction Effects ◽  
Group Effect ◽  
Piled Raft ◽  
Centrifuge Tests ◽  
Interaction Factor ◽  
Load Carrying ◽  
Lower Load ◽  
Load Tests ◽  
Pile Group Effect

In the present study, various interaction effects and load-carrying behavior of piled rafts embedded in clay were investigated. For this purpose, a series of centrifuge load tests were conducted using different types of model foundations, including single pile, group piles, piled raft, and unpiled raft. Different clay conditions were considered to prepare for centrifuge specimens. It was found that the pile group effect in clays is significant within initial loading range, showing lower load-carrying capacity. As settlement increases, the pile group effect becomes less pronounced. For both soft and stiff conditions, the values of the raft-to-pile (R-P) interaction factor varied initially, which became converged to some values around unity with increasing settlement. Similar tendency was observed for the pile-to-raft (P-R) interaction factor. The load responses of different pile components within the piled raft were not significantly different for the soft condition. For the stiff condition, the corner and inner piles showed the highest and lowest load-carrying capacities, respectively, due to piled-raft interaction effects. Correlations to cone resistance were analyzed and presented for the base and shaft resistances of piles for piled rafts.

scholarly journals Influences of Pile Group Effects on Wave Forces on an Offshore Bridge Pile-Cap Foundation

Challenges ◽  
2017 ◽  
Vol 8 (2) ◽  
pp. 30
Author(s):  
Baoshan Xiang ◽  
Bo Huang ◽  
Zhiying Yang ◽  
Bing Zhu ◽  
Ruitao Yin
Keyword(s):  
Pile Group ◽  
Wave Forces ◽  
Pile Cap ◽  
Group Effects

Experimental Research on Failure Mode of Micro-Pile in Landslide Reinforcement

2012 ◽  
Vol 226-228 ◽  
pp. 1338-1342
Author(s):  
Shu Feng Wang ◽  
Yong Peng Fu ◽  
Xin Zhao
Keyword(s):  
Failure Mode ◽  
Large Scale ◽  
Load Transfer ◽  
Slip Surface ◽  
Bending Moment ◽  
Pile Group ◽  
Physical Model Test ◽  
Pile Diameter ◽  
Surface Failure ◽  
Numerical Magnitudes

In recent years, micro-pile has been widely applied to landslide treatment engineering due to its advantages in application and construction, and the engineering effect is very evident. Large-scale physical model test was made for studying failure mode of micro-pile group in landslide, which indicated that numerical magnitudes between the displacement and the stress of the piles are better consistent along the load transfer direction. Concentrated destruction points locate on about three times the pile diameter up and down the slip surface. Failure mode of micro-pile in landslide treatment engineering is: pile of the loaded segment usually breaks for bending moment and shear force, and back of sliding side mainly exposes to the tension role, compared to role of tension of anchored segment in front of the micro-piles and compression behind of the piles.

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