Shaking table study on liquefaction behaviour of different saturated sands reinforced by stone columns     

Hadi Bayati  Mohammad Hossein Bagheripour 《Marine Georesources & Geotechnology》2013,31(7):801-815

Abstract

Liquefaction is a phenomenon developed in loose and saturated layers of sands subjected to dynamic or seismic loading, and often leads to excessive settlement and subsequent failures in structures. Several methods have been proposed to improve soil resistance against liquefaction, among which use of stone columns is one of the most applicable methods. In this research, the effect of stone columns with different geometries and arrangements on the liquefaction behaviour of loose and very loose saturated sands subjected to vibration is investigated using shaking table. Results of the experiments show that when using stone columns in sand layers, the level of maximum settlement is significantly reduced. Further, the presence of stone columns significantly reduces pore water pressure ratio. This further indicates that stone columns have a positive effect and reasonable performance, even in relatively strong earthquakes, provided that the number and cross-section of the columns are sufficient. In addition, stone columns reduce the pore water pressure dissipation time. Moreover, by increasing cross-sectional area and the number of columns, both pore water pressure and settlement decrease. Stone columns in loose sand have a greater effect on the reduction of pore water pressure compared to that of very loose sand.  相似文献   

Framework for assessing probability of exceeding a specified liquefaction-induced settlement at a given site in a given exposure time     

Chih-Chieh Lu  Jin-Hung Hwang  C. Hsein Juang  Chih-Sheng Ku  Zhe Luo 《Engineering Geology》2009,108(1-2):24-35

This paper presents a framework for assessing the probability of exceeding a specified liquefaction-induced settlement at a given site in a given exposure time. This framework deals not only with the effect of liquefaction (in terms of settlement) but also with probabilistic characterization of all possible ground motions at a given site (in terms of a joint distribution of a_max and M_w). Additionally, a new concept, referred to herein as liquefaction-induced settlement hazard curve, is introduced for assessing the annual rate of settlement exceedance at a given site. This settlement hazard curve concept has the potential to be a very useful tool in the field of geotechnical earthquake engineering. Satisfactory results are obtained in the demonstration examples analyzed with the proposed framework. Whereas the proposed framework is simple and effective, further refinements to this framework, especially on the treatment of epistemic uncertainty, are warranted.  相似文献   

Multilinear Regression Analysis for Seismic Response and Engineering Properties of Liquefiable Coromandel Coastal Soil Deposits   总被引：1，自引：0，他引：1  

S. Senthamilkumar  C. Natarajan  K. Muthukumaran 《Geotechnical and Geological Engineering》2009,27(3):439-453

This paper investigates the seismic characteristics and geotechnical properties with respect to the liquefaction potential of the deposits in the Coromandel coastal line of Nagapattinam town, Tamilnadu, India. A series of field tests were conducted using standard penetration test, cone penetration test and plate load test. Laboratory tests were conducted on the collected samples. From the results, a microzonation map was developed for the liquefaction potential and settlements. Some multilinear regression models between permeability, fines content, relative density, coefficient of curvature, coefficient of uniformity, mean particle size, factor of safety, settlement, standard penetration test values and cone penetration test values were developed. The shear wave velocity and shear modulus were calculated from the field penetration tests and correlations between the normalized values of peak ground accelerations, velocities and displacements, which were obtained from the equivalent linear ground motion analysis using SHAKE software, with other parameters of soil. From the results, it was found that at some of the areas are vulnerable to high amplification of waves even for small earthquake.  相似文献   

临界超静孔压确定液化深度的方法研究     

刘金韬  武强  董东林 《工程地质学报》2001,9(4):404-407

通过对地震时砂土层内超静孔压积累原理的研究, 提出了一种确定液化深度的方法, 并利用这一方法对 1976年唐山地震在沿海地区产生液化的深度进行了计算, 而且与实际资料进行了比较。  相似文献   

砂土液化诱发的地面侧移机理研究   总被引：4，自引：1，他引：4  

景立平  张荣祥 《地震工程与工程振动》1996,16(3):128-136

本文分析了砂土液化诱发的地面侧移的机理，提出了估计砂土液化诱发的地面侧移的一种新的方法。  相似文献   

Liquefaction characteristics of silts   总被引：1，自引：0，他引：1  

S. Singh 《Geotechnical and Geological Engineering》1996,14(1):1-19

Summary The paper presents a summary of the results of cyclical triaxial load testing of samples of silt and silty sands. The paper emphasizes differences in behaviour observed between reconstituted triaxial samples of clean sand, of sand containing 10, 20, 30 and 60% silt, pure silt, and undisturbed samples of silt and silty sand. An important observation is that the mechanisms of deformation for sit are different for reconstituted and undisturbed samples, the undisturbed sample having a specific geological structure which seems to slow down the excess pore water pressure accumulation, but which still results in cyclic deformations regularly increasing from the very beginning of the test and rapidly reaching high levels. The other important observation is that fine-grained noncohesive soils such as silts and silty sands can be as, or even more, susceptible to liquefaction as clean sands. Test results on samples of sand containing 10, 20 or 30% of silt indicate lesser resistance to liquefaction than pure sand samples. The paper shows the difficulty in identifying a representative parameter to compare the behaviour of silts and silty sands with pure sand, and it seems that more research will be needed in this area.  相似文献   

Nonlinear numerical method for earthquake site response analysis I — elastoplastic cyclic model and parameter identification strategy   总被引：3，自引：1，他引：3  

Fernando Lopez-Caballero  Arezou Modaressi-Farahmand Razavi  Hormoz Modaressi 《Bulletin of Earthquake Engineering》2007,5(3):303-323

This paper, along with its companion paper, presents the importance of the adequate soil behaviour model to simulate earthquake site response analysis. An elastoplastic model taking into account the elementary necessary plastic mechanisms such as progressive friction mobilization, Coulomb type failure, critical state and dilatancy/contractance flow rule, is used. However, one of the obstacles in the use of elastoplastic models in the everyday design processes for evaluation of the seismic soil response is the difficulty in identifying their parameters. In this paper, a methodology to identify a coherent set of parameters of the elastoplastic model for a given type of soil is presented. The strategy behind the decision making process proposed here is based on the use of minimum physical and easily measurable properties of the soil to directly provide or indirectly assess the required model parameters.  相似文献   

Analysis of stability of earthen dams in kachchh region, Gujarat, India   总被引：2，自引：0，他引：2  

G.L. Sivakumar Babu  Amit Srivastava  V. Sahana   《Engineering Geology》2007,94(3-4):123-136

The Kachchh region of Gujarat, India bore the brunt of a disastrous earthquake of magnitude M_w = 7.6 that occurred on January 26, 2001. The major cause of failure of various structures including earthen dams was noted to be the presence of liquefiable alluvium in the foundation soil. Results of back-analysis of failures of Chang, Tappar, Kaswati and Rudramata earth dams using pseudo-static limit equilibrium approach presented in this paper confirm that the presence of liquefiable layer contributed to lesser factors of safety leading to a base type of failure that was also observed in the field. Following the earthquake, earth dams have been rehabilitated by the concerned authority and it is imperative that the reconstructed sections of earth dams be reanalyzed. It is also increasingly realized that risk assessment of dams in view of the large-scale investment made and probabilistic analysis is necessary. In this study, it is demonstrated that the probabilistic approach when used in conjunction with deterministic approach helps in providing a rational solution for quantification of safety of the dam and in the estimation of risk associated with the dam construction.  相似文献   

An integrated earthquake damage assessment methodology and its application for two districts in Istanbul, Turkey     

S. Feyza Cinicioglu  Ilknur Bozbey  Sadik Oztoprak  M. Kubilay Kelesoglu   《Engineering Geology》2007,94(3-4):145-165

This paper presents an integrated, earthquake-damage assessment that standardizes and quantifies methods of analysis. The proposed methodology evaluates all damage-causing phenomena, both individually and in combination. This approach inherently relates to soil-structure interactions by quantifying site-specific geotechnical and structural properties. Specifically considered is ground shaking, the primary damage-causing phenomenon. Also evaluated are the collateral effects of liquefaction, degradation of seismic-bearing capacity and slope failure (landslides). The methodology incorporates a literature-derived probabilistic assessment of damage-causation, and is interpreted and presented as single numbers deemed “Damage Grades.” These damage grades integrate the initial probabilistic evaluation with professional experience and judgment in order to determine potential damage to a particular structure at a particular location. This methodology was applied, with success, to two different locations in Istanbul, Turkey. It should be tested by engineering geologists and geotechnical engineers, for it may be applicable to earthquake-prone areas elsewhere.  相似文献   

Development of new drain method for protection of existing pile foundations from liquefaction effects   总被引：1，自引：0，他引：1  

Naoyuki Harada  Ikuo Towhata  Tadashi Takatsu  Shinsuke Tsunoda  Vlatko Sesov 《Soil Dynamics and Earthquake Engineering》2006,26(2-4):297-312

Pile foundation as well as other underground structures could be seriously affected by soil liquefaction during strong earthquakes. Damages on pile foundation due to liquefaction can be reduced by implementation of some soil improvement method. Main objective of present study is developing of drain method that can improve the soil in order to mitigate the destructiveness of liquefaction on superstructure supported by pile foundation. Series of shaking table tests were conducted on 2×2 pile foundation and soil model was improved by drains. Configurations of drains around piles, intensity of shaking were one of the parameters that were changing during the tests in order to investigate the response of pile foundation in improved soil condition.Shaking table tests and performed On-site experiment showed the following effects of the new drain method. (1) When the intensity of earthquake motion is 200 gal or less, generation of excess pore water pressure is reduced and the pile bending moment is decreased, (2) when the intensity of earthquake motion is stronger (300 gal or more), drainage effect prevents disappearance of subgrade reaction, and (3) proposed new type of drain can control excess pore water pressure without clogging.  相似文献