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Critical embedment depth of a rigid retaining wall against overturning in unsaturated soils considering intermediate principal stress and strength nonlinearity

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Journal of Central South University 2016年第4期23卷 944-954页

作者：张常光陈新栋范文 School of civil engineering Chang'an University School of Highway Chang'an University School of Geological engineering and geomatics Chang'an University

The overturning stability is vital for the retaining wall design of foundation pits, where the surrounding soils are usually unsaturated due to water draining. Moreover, the intermediate principal stress does affect the unsaturated soil strength; meanwhile, the relationship between the unsaturated soil strength and matric suction is nonlinear. This work is to present closed-form equations of critical embedment depth for a rigid retaining wall against overturning by means of moment equilibrium. Matric suction is considered to be distributed uniformly and linearly with depth. The unified shear strength formulation for unsaturated soils under the plane strain condition is adopted to characterize the intermediate principal stress effect, and strength nonlinearity is described by a hyperbolic model of suction angle. The result obtained is orderly series solutions rather than one specific answer; thus, it has wide theoretical significance and good applicability. The validity of this present work is demonstrated by comparing it with a lower bound solution. The traditional overturning designs for rigid retaining walls, in which the saturated soil mechanics neglecting matric suction or the unsaturated soil mechanics based on the Mohr-Coulomb criterion are employed, are special cases of the proposed result. Parametric studies about the intermediate principal stress, matric suction and its distributions along with two strength nonlinearity methods on a new defined critical buried coefficient are discussed.

关键词： unsaturated soils retaining walls overturning stability critical embedment depth intermediate principal stress strength nonlinearity

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Characterization of the micro-interfacial interactions of heterogeneous particulate matter(fine-grained sediment and microplastics) with copper ions

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International Journal of Sediment Research 2023年第6期38卷 871-879页

作者： Jing Ou Zhihe Chen Tung-Chiung Chang civil engineering School Sun Yat-sen University engineering Research Center for Water Security Regulation in Southern China of Guangdong Province department of civil engineering and geomatics Cheng Shiu University

Particulate matter,such as sediment and microplastics(MPs),in aqueous environments has comparable micro-interfacial ***,the micro-interfacial characteristics of heterogeneous particulate matter are complex and are not fully *** this study,micro-interfacial kinetics and the interactions governing copper(Cu) ion adsorption to PP-sediment were investigated using microinterfacial characterization experiments and kinetic experiments for Cu ion absorption to sediment,polypropylene(PP),and PP-sediment *** results show that(1) a pseudo-second-order model can be used to accurately describe the micro-interfacial kinetics of Cu ion adsorption to PP-sediment,indicating that chemical adsorption dominates the *** Cu,the adsorption capacity,qe,of PP-sediment is approximately 0.4808 mg/g,between that of sediment and PP.(2) Film diffusion is the rate-controlling process in the early adsorption *** diffusion gradually becomes the controlling process as the film diffusion constant(kfd) decreases and the film diffusion model becomes less applicable,but intraparticle diffusion is weaker in the PP-sediment system than in the sedimentonly system.(3) The applicability of the intraparticle diffusion model for Cu ion adsorption to PP-sediment in the later stage of adsorption is between that of the sediment and PP ***,the heterogeneous aggregation of sediment and PP affects the micro-interfacial interactions of both types of particulate *** current study contributes to a better understanding of the microinterfacial interactions of heterogeneous particulate matter(such as fine-grained sediment and MPs)with heavy metal ions in aqueous environments.

关键词： Sediment Microplastic (MP) Micro-interfacial interaction Kinetics Heterogeneous aggregation

Impact of different sampling rates on precise point positioning performance using online processing service

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Geo-Spatial Information Science 2021年第2期24卷 302-312,I0008页

作者： Serdar Erol Reha Metin Alkan İ.Murat Ozulu Veli Ilçi department of geomatics engineering Istanbul Technical UniversityIstanbulTurkey department of Technical Programs Hitit UniversityÇorumTurkey department of geomatics engineering Ondokuz Mayıs UniversitySamsunTurkey

In this study,the effect of different sampling rates(*** recording interval)on the Precise Point Positioning(PPP)solutions in terms of accuracy was *** this purpose,a field test was carried out inÇorum province,Turkey,on 11 September *** this context,a Geodetic Point(GP)was established and precisely coordinated.A static GNSS measurement was occupied on the GP for about 4-hour time at 0.10 second(s)/10 Hz measurement intervals with the Trimble R10 geodetic grade GNSS *** original observation file was converted to RINEX format and then decimated into the different data sampling rates as 0.2 s,0.5 s,1 s,5 s,10 s,30 s,60 s,and 120 *** these RINEX observation files were submitted to the Canadian Spatial Reference System-Precise Point Positioning(CSRS-PPP)online processing service the day after the data collection date by choosing both static and kinematic processing *** this way,PPP-derived static coordinates,and the kinematic coordinates of each measurement epoch were *** PPP-derived coordinates obtained from each decimated sampling intervals were compared to known coordinates of the GP for northing,easting,2D position,and height *** to the static and kinematic processing results,high data sampling rates did not change the PPP solutions in terms of accuracy when compared to the results obtained using lower sampling *** results of this study imply that it was not necessary to collect GNSS data with high-rate intervals for many surveying projects requiring cm-level accuracy.

关键词： Precise Point Positioning(PPP) online GNSS postprocessing service high-rate GNSS sampling rate monitoring structure behavior

Towards a collaborative global land cover information service

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International Journal of Digital Earth 2017年第4期10卷 356-370页

作者： Jun Chen Songnian Li Hao Wu Xianjun Chen National geomatics Center of China BeijingPeople’s Republic of China department of civil engineering Ryerson UniversityTorontoCanada

The need and critical importance of global land cover and change information has been well *** rich collection of such information has been made available,the lack of necessary information services to support its easy access,analysis and validation makes it difficult to find,evaluate,select and reuse them through well-designed *** at promoting the development of the needed global land cover information services,this paper presents a conceptual framework for developing a Collaborative Global Land Cover Information Service(CoGland),followed by discussions on its implementation *** framework supports connected and shared land cover and change web services around the world to address resource sharing,community service and cross-board collaboration *** can benefit several recent international initiatives such as Future Earth,and many societal benefit *** paper further proposes that CoGland be developed within the framework of the Group on Earth Observations with the support of a number of key organizations such as the United Nations Expert Committee on Global Geospatial Information Management,the International Society for Photogrammetry and Remote Sensing,and International Society of Digital *** is hoped that this paper can serve as a starting point for further discussions on CoGland developments.

关键词： Global land cover information web service collaborative

The mechanical and water absorption properties of carbon fiber buoyancy materials under hydrostatic pressure

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Science China Technological Sciences 2025年第1期 251-265页

作者： Fanglin CONG Zihan LI Guocai YU Yang JIN Zixu ZHU Linzhi WU College of Aerospace and civil engineering Harbin Engineering University Key Laboratory of Advanced Ship Materials and Mechanics Harbin Engineering University department of Basic Courses Naval University of Engineering

Buoyancy material technology is of paramount importance for the development of marine engineering. In this study,a novel carbon fiber buoyancy material(CFBM) is designed and prepared by utilizing composite circular tubes with light weight and high strength. To reveal the failure mechanism under hydrostatic pressure, a finite element model(FEM) based on the three-dimensional Hashin and Yeh failure criterion is developed and validated experimentally. Both the simulated and experimental results indicate that the hydrostatic strength of the CFBM is mainly determined by the buckling of carbon fiber tubes located at the edges of the CFBM. Parametric analysis is conducted to investigate the effect of the number of unit-cells,length, and wall thickness of carbon fiber tubes on the mechanical properties of the CFBM. In addition, a 60-day water absorption test of the CFBM at 12.5 MPa is conducted to characterize its durability. Experimental results indicate that the maximum water absorption rate of the CFBM is 0.59% and the hydrostatic strength is reduced by only 7.97% during the 60-day test period. Finally, the designed CFBM is used at the water depth of 1000 m as buoyancy material. Compared with traditional buoyancy materials, the proposed CFBM has significant advantages in both hydrostatic strength and density. This work has broad engineering application prospects and is of high significance for promoting the implementation of carbon fiber composites in the ocean engineering field.

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Model Tests on the Effect of Dip Angles on Flow Behavior of Liquefied Sand

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Journal of Earth Science 2023年第2期34卷 381-385页

作者： Wenyang Li Yu Huang School of Geological engineering and geomatics Chang'an UniversityXi'an 710054China department of Geotechnical engineering College of Civil EngineeringTongji UniversityShanghai 200092China

The flow behavior of liquefied sand is reported using a self-developed testing system that enables the flow processes of liquefied sand to be studied at different slopes of the soil *** test device is mainly composed of a vibrating table,a transparent model box and a high-speed video monitoring *** tests replicated the horizontal and sloping flows of saturated sand in the model box,which can be tilted to various angles to study the flow characteristics of liquefied *** high-speed video monitoring camera captured and recorded the processes within the flowing *** increasing downslope,the strain,strain rate,duration time,and sand flow distance *** results of our experiment indicate that when selecting sites for engineering structures,the surface downslopes should be taken into account if liquefiable soils are ***,some suggestions regarding site assessment and structural design for sites prone to liquefaction were presented.

关键词： earthquake liquefied sand dip angle soil flow model test engineering geology

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Semi-active model predictive control for 3rd generation benchmark problem using smart dampers

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Earthquake engineering and engineering Vibration 2007年第3期6卷 307-315页

作者：颜桂云孙炳楠吕艳平 department of civil engineering Fujian University of Technology department of civil engineering Zhejiang University department of civil engineering Fuzhou University

A semi-active strategy for model predictive control （MPC）, in which magneto-rheological dampers are used as an actuator, is presented for use in reducing the nonlinear seismic response of high-rise buildings. A multi-step predictive model is developed to estimate the seismic performance of high-rise buildings, taking into account of the effects of nonlinearity, time-variability, model mismatching, and disturbances and uncertainty of controlled system parameters by the predicted error feedback in the multi-step predictive model. Based on the predictive model, a Kalman-Bucy observer suitable for semi-active strategy is proposed to estimate the state vector from the acceleration and semi-active control force feedback. The main advantage of the proposed strategy is its inherent stability, simplicity, on-line real-time operation, and the ability to handle nonlinearity, uncertainty, and time-variability properties of structures. Numerical simulation of the nonlinear seismic responses of a controlled 20-story benchmark building is carried out, and the simulation results are compared to those of other control systems. The results show that the developed semi-active strategy can efficiently reduce the nonlinear seismic response of high-rise buildings.

关键词： nonlinear seismic response model predictive control semi-active strategy benchmark problem magnetorheological damper

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International Journal of Digital Earth 2017年第1期10卷 85-102页

作者： Athos Agapiou Remote Sensing and Geo-Environment Laboratory Eratosthenes Research CentreDepartment of Civil Engineering and GeomaticsCyprus University of TechnologyLimassolCyprus

This paper aims to demonstrate results and considerations regarding the use of remote sensing big data for archaeological and Cultural Heritage management large scale *** this purpose,the Earth Engine©developed by Google©was *** Engine©provides a robust and expandable cloud platform where several freely distributed remote sensing big data,such as Landsat,can be accessed,analysed and *** different applications are presented here as follows:the first one is based on the evaluation of multi-temporal Landsat series datasets for the detection of buried Neolithic tells(‘magoules’)in the area of Thessaly,in Greece using linear orthogonal *** second case exploits European scale multi-temporal DMSP-OLS Nighttime Lights Time Series to visualize the impact of urban sprawl in the vicinity of UNESCO World Heritage sites and *** applications highlight the considerable opportunities that big data can offer to the fields of archaeology and Cultural Heritage,while the studies also demonstrate the great challenges that still are needed to be overcome in order to make the exploitation of big data process manageable and fruitful for future applications.

关键词： Big data remote sensing archaeology cultural heritage Earth Engine orthogonal equations urban sprawl

Implementation of serverless cloud GIS platform for land valuation

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International Journal of Digital Earth 2021年第7期14卷 836-850页

作者： Muhammed Oguzhan Mete Tahsin Yomralioglu geomatics engineering department Istanbul Technical UniversityIstanbulTurkey

Cloud computing enables performing computations and analysis tasks and sharing services in web-based computer centres instead of local desktop *** of the most used areas of cloud computing is geographic information systems(GIS)*** Desktop GIS products are still used in the community frequently,Web GIS and Cloud GIS applications have drawn attention and have become more efficient for *** this study,a serverless Cloud GIS framework is implemented for the land valuation *** order to store,analyse,and share geospatial data,the Aurora Serverless PostgreSQL database is created on Amazon Web Services(AWS).While adopting Aurora Serverless PostgreSQL as a database management system,a simple point in polygon analysis conducted to compare the performances with Amazon Relational Database Service(RDS)*** showed that the serverless database responded to the query faster and scaled up during high workload to decrease ***,parcel vector data,which conveys ownership information and land values attributes,is shared directly from the PostGIS database as vector *** S3 and AWS Lambda services are used for storing and disseminating raster-based land value map *** visualize all shared data and maps through a web browser,open source web mapping library Mapbox GL JS is used.

关键词： Serverless cloud computing cloud GIS open source GIS real estate valuation value map