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Frontiers of Structural and Civil Engineering 2014年第3期8卷 292-307页

作者： sadegh rezaei asskar janalizadeh choobbasti Department of Civil Engineering Babol University of Technology Babol P O. Box 484 Iran

Recent researchers have discovered microtremor applications for evaluating the liquefaction potential. Microtremor measurement is a fast, applicable and cost-effective method with extensive applications. In the present research the liquefaction potential has been reviewed by utilization of microtremor measurement results in Babol city. For this purpose microtremor measurements were performed at 60 measurement stations and the data were analyzed by suing Nakmaura＇s method. By using the fundamental frequency and amplification factor, the value of vulnerability index （Kg） was calculated and the liquefaction potential has been evaluated. To control the accuracy of this method, its output has been compared with the results of Seed and Idriss [1] method in 30 excavated boreholes within the study area. Also, the results obtained by the artificial neural network （ANN） were compared with microtremor measurement. Regarding the results of these three methods, it was concluded that the threshold value of liquefaction potential is Kg = 5. On the basis of the analysis performed in this research it is concluded that microtremors have the capability of assessing the liquefaction potential with desirable accuracy.

关键词： liquefaction microtremor vulnerability index artificial neural networks (ANN) microzonation

Application of the microtremor measurements to a site effect study

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Earthquake Science 2017年第3期30卷 157-164页

作者： sadegh rezaei asskar janalizadeh choobbasti Department of Civil Engineering Babol University of Technology

Earthquake has left much life and property damages. The occurrence of such events necessitates the execution of plans for combating the earthquakes. One of the most important methods for combating earthquakes includes assessing dynamic characteristics of soil and site effect. One of the methods by which one can state dynamic characteristics of the soil of an area is the measurement of microtremors. Microtremors are small-scale vibrations that occur in the ground and have an amplitude range of about 0.1-1 microns. Microtremor measurement is fast, applica- ble, cost-effective. Microtremor measurements were taken at 15 stations in the Babol, north of Iran. Regarding H/V spectral ratio method, peak frequency and amplifica- tion factor were calculated for all microtremor stations. According to the analysis, the peak frequency varies from 0.67 to 8.10 Hz within the study area. Also, the authors investigated the validity of the results by comparing them with SESAME guidelines and geotechnical conditions of study area. The microtremor analysis results are consistent with SESAME guidelines and geotechnical condition of study area. The results show that the microtremor obser- vations are acceptable methods for assessing dynamic characteristics of soil and site effect in the Babol City.

关键词： Site effect Dynamic characteristics Microtremor Peak frequency Amplification factor

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Application of random set method in a deep excavation: based on a case study in Tehran cemented alluvium

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Frontiers of Structural and Civil Engineering 2019年第1期13卷 66-80页

作者： Arash SEKHAVATIAN asskar janalizadeh choobbasti Department of Civil Engineering Babol Noshirvani University of TechnologyBabolIran

The design of high-rise buildings often necessitates ground excavation,where buildings are in close proximity to the construction,thus there is a potential for damage to these *** paper studies an efficient user-friendly framework for dealing with uncertainties in a deep excavation in layers of cemented coarse grained soil located in Tehran,Iran by non-deterministic Random Set (RS)*** order to enhance the acceptability of the method among engineers,a pertinent code was written in FISH language of FLAC2D software which enables the designers to run all simulations simultaneously,without cumbersome procedure of changing input variables in every individual *** could drastically decrease the computational effort and cost imposed to the project,which is of great importance especially to the *** results are presented in terms of probability of occurrence and most likely values of the horizontal displacement at top of the wall at every stage of ***,a methodology for assessing the credibility of the uncertainty model is presented using a quality *** was concluded that performing RS analysis before the beginning of every stage could cause great economical savings,while improving the safety of the project.

关键词： uncertainty reliability analysis deep excavations random set method finite difference method

Evaluation of site response characteristic using nonlinear method(Case study: Babol, Iran)

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Frontiers of Structural and Civil Engineering 2014年第1期8卷 69-82页

作者： asskar janalizadeh choobbasti sadegh rezaei Farzad FARROKHZAD Pedram Haidarzaeh AZAR Department of Civil Engineering Babol University of Technology

In this the present study, an attempt has been made to evaluate the seismic hazard considering local site effects by carrying out detailed geotechnical site characterization in Babol, Iran. Use of geotechnical data and synthesis of drilling data extracted from the Babol's subsurface database have enabled authors to determine the geotechnical properties of each site. These data are consisted of twenty five boreholes up to depth of 40 m. Based on the obtained data from geotechnical investigation the study area is divided to five zones. Dynamic analysis was performed in time domain,using fully nonlinear model by PLAXIS. A series of analysis in the study area showed the site period, ranging from 0.4 to0.8 s. Finally the obtained response spectra from fully nonlinear method were compared with site response spectra of Iran's 2800(earthquake) code.

关键词： fully nonlinear method site effect dynamic analysis response spectra

Innovative piled raft foundations design using artificial neural network

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Frontiers of Structural and Civil Engineering 2020年第1期14卷 138-146页

作者： Meisam RABIEI asskar janalizadeh choobbasti Department of Civil Engineering Babol Noshirvani University of TechnologyBabol ***Iran

Studying the piled raft behavior has been the subject of many types of research in the field of geotechnical *** studies have been conducted to understand the behavior of these types of foundations,which are often used for uniform loading on the raft and piles with the same length,while generally the transition load from the upper structure to the foundation is non-uniform and the choice of uniform length for piles in the above model will not be optimally economic and *** most common method in identifying the behavior of piled rafts is the use of theoretical relationships and software *** precise identification of this type of foundation behavior can be very difficult due to several influential parameters and interaction of set behavior,and it will be done by doing time-consuming computer analyses or costly full-scale physical *** the meantime,the technique of artificial neural networks can be used to achieve this goal with minimum time consumption,in which data from physical and numerical modeling can be used for network *** of the advantages of this method is the speed and simplicity of using *** this paper,a model is presented based on multi-layer perceptron artificial neural *** this model pile diameter,pile length,and pile spacing is considered as an input parameter that can be used to estimate maximum settlement,maximum differential settlement,and maximum raft *** this model,we can create an extensive domain of results for optimum system selection in the desired piled raft *** of neural network indicate its proper ability in identifying the piled raft *** presented procedure provides an interesting solution and economically enhancing the design of the piled raft foundation *** innovative design method reduces the time spent on software analyses.

关键词： innovative design piled raft foundation neural network optimization

Microstructure characteristics of cement-stabilized sandy soil using nanosilica

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Journal of Rock Mechanics and Geotechnical Engineering 2017年第5期9卷 981-988页

作者： asskar janalizadeh choobbasti Saman Soleimani Kutanaei Department of Civil Engineering Babol University of Technology Babol Iran

An experimental program was conducted to explore the impact of nanosilica on the microstructure and mechanical characteristics of cemented sandy *** agent included Portland cement type *** content was 6% by weight of the sandy *** was added in percentages of 0%,4%,8% and 12% by weight of *** samples were prepared with relative density of 80% and optimum water content and cured for 7 d,28 d and 90 *** characteristics of cementnanosilica-sand mixtures after 90 d of curing have been explored using atomic force microscopy(AFM),scanning electron microscopy(SEM) and X-ray diffraction(XRD) *** of curing time on microstructure properties of cemented sandy soil samples with 0% and 8% nanosilica have been investigated using SEM *** compression test(for all curing times) and compaction test were also *** SEM and AFM tests results showed that nanosilica contributes to enhancement of cemented sandy soil through yielding denser,more uniform *** XRD test demonstrated that the inclusion of nanosilica in the cemented soil increases the intensity of the calcium silicate hydrate(CSH) peak and decreases the intensity of the calcium hydroxide(CH) *** results showed that adding optimum percentages of nanosilica to cement-stabilized sandy soil enhances its mechanical and microstructure properties.

关键词： Scanning electron microscopy(SEM) Atomic force microscopy(AFM) X-ray diffraction(XRD) Cement Nanosilica

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Evaluation of site response characteristic using nonlinear method （Case study： Babol, Iran）

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Frontiers of Structural and Civil Engineering 2014年第1期8卷 69-82页

作者： asskar janalizadeh choobbasti sadegh rezaei Farzad FARROKHZAD Pedram Haidarzaeh AZAR Department of Civil Engineering Babol University of Technology Babol Mazandaran 484 Iran

In this the present study, an attempt has been made to evaluate the seismic hazard considering local site effects by carrying out detailed geotechnical site characterization in Babol, Iran. Use of geotechnical data and synthesis of drilling data extracted from the Babol＇s subsurface database have enabled authors to determine the geotechnical properties of each site. These data are consisted of twenty five boreholes up to depth of 40 m. Based on the obtained data from geotechnical investigation the study area is divided to five zones. Dynamic analysis was performed in time domain, using fully nonlinear model by PLAXIS. A series of analysis in the study area showed the site period, ranging from 0.4 to 0.8 s. Finally the obtained response spectra from fully nonlinear method were compared with site response spectra of Iran＇s 2800 （earthquake） code.

关键词： fully nonlinear method site effect dynamic analysis response spectra

Dynamic equivalent soil characteristics identification using earthquake records

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Earthquake Science 2018年第3期31卷 166-173页

作者： asskar janalizadeh choobbasti Saman Soleimani Kutanaei Department of Civil Engineering Babol University of Technology

Techniques for soil property estimation can be categorized into two main groups, in-situ and laboratory methods. Previous investigations indicated that strong ground motions record provides a very useful tool to estimating the in-situ characteristics of soil. The main objective of the present work is to utilize the particle swarm optimization algorithm（PSOA） integrated with linear site response method to obtain the equivalent soil profile characteristics from the available surface and bedrock earthquake motion records. To demonstrate the numerical efficiency and the validity of this approach, the procedure is validated against an available case. Then this procedure is utilized to identify the soil properties profiles of the site by using strong ground motions data recorded during the Bam earthquake of December 26, 2003. The magnitude and PGA of Bam earthquake were MW 6.6 and 0.8 g respectively.

关键词： identification ground response particle swarm optimization algorithm site effect

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