Verifying adequacy of the seismic deformation method by using real examples of earthquake damage   总被引：1，自引：0，他引：1  

Xiu Luo  Yoshitaka Murono  Akihiko Nishimura 《Soil Dynamics and Earthquake Engineering》2002,22(1)

In a seismic design, the dynamic loads are generally dependent on the inertial interaction caused by earthquake. But for the foundations embedded in soil, the dynamic loads are influenced by both the inertial and kinematic interactions among superstructure, foundation and soil. Especially, when a foundation is embedded in soft surface ground, the effects due to the kinematic interaction increase and should be considered in seismic design. For this reason, a method called seismic deformation method (SDM), which is suitable for an intensive earthquake motion (level 2 earthquake motion), has been stipulated recently in a new design code called Seismic Design Code for railway structures (the Railway Code, drawn up by Railway Technical Research Institute, Japan, 1999) [Railway Technical Research Institute. Seismic Design Code for railway structures. Tokyo: Maruzen; 1999]. In order to grasp the suitability of the SDM to actual structures, pile foundations, which experienced the Hyogoken-Nanbu earthquake, were taken as the objects for investigations. Comparison studies between the SDM analysis and reconnaissance were conducted. As a result, the adequacy of the SDM to actual foundations was confirmed to prove good agreement between the two results from the viewpoint of engineering practice.In addition, determination of indices for seismic-performance evaluation and speculation of damage mechanism of the foundations are also discussed in this paper.  相似文献   

Effects of the construction of Scroby Sands offshore wind farm on the prey base of Little tern Sternula albifrons at its most important UK colony     

Perrow MR  Gilroy JJ  Skeate ER  Tomlinson ML 《Marine pollution bulletin》2011,62(8):1661-1670

Despite widespread interest in the impacts of wind farms upon birds, few researchers have examined the potential for indirect or trophic (predator-prey) effects. Using surface trawls, we monitored prey abundance before and after construction of a 30 turbine offshore wind farm sited close to an internationally important colony of Little terns. Observations confirmed that young-of-the-year clupeids dominated chick diet, which trawl samples suggested were mainly herring. Multivariate modelling indicated a significant reduction in herring abundance from 2004 onwards that could not be explained by environmental factors. Intensely noisy monopile installation during the winter spawning period was suggested to be responsible. Reduced prey abundance corresponded with a significant decline in Little tern foraging success. Unprecedented egg abandonment and lack of chick hatching tentatively suggested a colony-scale response in some years. We urge a precautionary approach to the timing and duration of pile-driving activity supported with long-term targeted monitoring of sensitive receptors.  相似文献   

Inclination correction of the parallel seismic test for pile length detection   总被引：1，自引：0，他引：1  

Sheng-Huoo Ni  Yan-Hong Huang  Xian-Min Zhou  Kuo-Feng Lo 《Computers and Geotechnics》2011

An inclination factor is proposed in this paper to enhance the accuracy of the parallel seismic method for pile length assessment when a borehole is not drilled perfectly parallel with the tested foundation. Three-dimensional axisymmetric finite element models were performed to show the effects of the inclined angles of the borehole. A series of parametric studies, including the pile length, the borehole distance, and the wave propagation velocity of the soil, were also carried out to investigate their effects on the derived modified factor for pile length prediction. The results from the numerical models show that the estimated error (5–20%) of the pile lengths increases with the increasing inclined angles, and can be reduced to less than 5% when the derived inclination factor is considered. In addition, the slope of the top fitted straight line in the first arrival time versus depth plot does not represent the true P-wave velocity of the tested structure if the borehole is not perfectly parallel with the pile foundation and use of this value to determine the quality of the tested pile foundation would be unsuitable. However, this unreasonable value of the P-wave velocity of the tested pile can be used as a guide, representing the inclination of the borehole.  相似文献   

Improving dynamic soil parameters and advancing the pile signal matching technique     

《Computers and Geotechnics》2013

The pile signal matching technique widely used for estimating vertical resistances of piles during construction is highly influenced by the assumed dynamic soil parameters. Due to the lack of understanding and supporting data, constant soil parameters for the entire pile length have been routinely used. This practice is unrealistic and compromises the signal match quality. Using recently completed field tests, this paper develops empirical equations for dynamic soil parameters in terms of measureable soil properties and proposes an improved signal matching technique, thereby allowing for better match quality.  相似文献   

Pile group response to liquefaction-induced lateral spreading: E-Defense large shake table test     

《Soil Dynamics and Earthquake Engineering》2013

This paper presents the results of a large-scale shake table test at E-Defense facility on a pile group located adjacent to a gravity-type quay wall and were subjected to liquefaction-induced large ground displacements. Extensive liquefaction-induced large ground lateral spreading displaced the quay wall about 2.2 m and damaged the pile foundation. The pile foundation consisted of a six-pile group which supported a footing and a superstructure model. Large lateral soil displacements were measured by several sensors such as inclinometers and the results favorably agreed with the directly observed deformations. Soil lateral displacement decreased as the distance from the quay wall increased landward. The piles were densely instrumented and the measured bending strain records were able to explain the damage to the piles. Lateral pressures of the liquefied soil exerted on the piles were measured using earth pressure (EP) sensors. The application of two design guidelines (JRA [1] and JSWA [2]) for estimation of liquefaction-induced lateral pressure on piles is discussed and their advantages and shortcomings are addressed. Furthermore, two simplified methods (Shamoto et al. [3] and Valsamis et al. [4]) are employed to predict the extent of liquefaction-induced large ground displacements and they are compared to the measured deformations. Finally, their accuracy for predicting the liquefaction-induced lateral displacements is evaluated and practical recommendations are made.  相似文献   

A numerical and experimental study of hollow steel pile in layered soil subjected to lateral dynamic loading     

《Soil Dynamics and Earthquake Engineering》2013

The present study aims at investigating the nonlinear behavior of single hollow pile in layered soil subjected to varying levels of horizontal dynamic load. A finite element model has been developed using commercially available FEM based software. Mohr–Coulomb plasticity model is used to simulate the soil plasticity whereas the pile-material is idealized as elastic. Numerical results are validated comparing with the experimental results. The experimental investigations were carried out in the field located at IIT Kharagpur. Two types of motion: horizontal and rocking are studied. The effects of various influencing parameters, namely, exciting moment, length and diameter of the pile etc. on the nonlinear dynamic response of piles are investigated. It is found that separation of pile from the surrounding soil considerably affects the resonance frequency and amplitude of the pile foundations.  相似文献   

A study of the reduction of ground vibrations by an active generator     

《Soil Dynamics and Earthquake Engineering》2016

This paper presents the concept of using an additional generator to prevent ground vibrations. A linear, transversally isotropic three dimensional half-space with the hysteretic damping model, acted upon by a harmonic vertical excitation is assumed. Equations of motion for the transversally isotropic ground model with the absorbing boundary conditions are presented and numerically integrated using FlexPDE software, based on the finite element method. The efficiency of the solution is analysed in terms of reducing the vertical and horizontal components of ground surface vibrations. Results in the form of a dimensionless amplitude reduction factor are presented for four different locations of a generator. The influence of the soil parameters and layers locations on the additional generator's efficiency is investigated. The vibration reduction efficiency in a four-story building is also presented.  相似文献   

Superpile system: A feasible alternate foundation for tension leg platforms in deep water     

L. F. Albert  R. D. Holtz  E. Magris 《Marine Georesources & Geotechnology》2013,31(2):133-158

Abstract

This article discusses a possible alternate foundation system for a tension leg platform (TLP) in deep water. It was developed through Tecnomare S.p.A. for Agip S.p.A. during a feasibility study of a site located in the southern Adriatic Sea having a water depth of 827 m. The system is a combination of a pile‐gravity foundation, with relatively short (?20 m) steel piles of very large diameter (6 to 12 m) called “superpiles,”; which are closed at the top and open at the bottom. The superpiles are installed in soft soil under the effect of self‐weight and active suction. Permanent tension of the TLP tendons is equilibrated by self‐weight only; tension due to wave action is equilibrated by the weight of the soil inside the superpiles. In fact, a pulsating tension applied to the superpiles generates a suction in the pore water that tends to keep the soil plug inside the cylinder and prevents the cylinder as a whole from being extracted from the (impervious) foundation soil.

The results of analyses of the installation and in service behavior of superpiles are described on conventional principles of soil mechanics and related to a typical profile at the Adriatic site. Installation problems are briefly discussed; then the stability in service is examined to evaluate the capacity of superpiles in compression and tension and the associated factors of safety. Finally, considering the pore pressure gradient generated by the applied tension inside the soil plug, the flow rate and related deformations during storms and during the entire expected life of the TLP are evaluated.

The proposed superpile system appears to be feasible, simple to install, and economical. Further study and experimental research are justified to optimize the system.  相似文献   

A hybrid element method for dynamics of piles and pile groups in transversely isotropic media     

《Computers and Geotechnics》2017

A hybrid analytical-numerical method is proposed for the dynamic analysis of single piles and pile groups embedded in semi-infinite transversely isotropic media. In the method proposed, the soil-pile system is modeled using finite elements combined with massless rigid radiation discs representing pile-soil-pile interaction. The elasto-dynamic response of the radiation discs buried at different depths in a transversely isotropic half-space is analytically derived in a transform domain using a set of complete potential functions. A Boussinesq-type loading distribution is introduced to act on the disc region to achieve the proper mode of deformation at the cross sections of piles. Numerical results and comparisons with known analytical/numerical solutions are presented, demonstrating the application of the method.  相似文献   

Pile response subjected to rock blasting induced ground vibration near soil-rock interface     

《Computers and Geotechnics》2017

Blasting has been widely used in mining and construction industries for rock breaking. Ground vibration induced by blasting is an inevitable side effect that may cause damage to nearby structures, if not properly controlled. In this study, response and possible damage of rock-socketed pile near soil-rock interface subjected to ground shock excitations are investigated and quantified with coupled SPH-FEM method. Results indicate that the base of the pile is relatively vulnerable and that the soil properties significantly influence on response of pile subjected to a specific blast load. Furthermore, based on the numerical results, ground vibration attenuation equation is proposed.  相似文献