Pub Date : 2020-05-26DOI: 10.5772/intechopen.91720
S. Hemeda
The Greek-Roman rock-cut tombs at Alexandria, Egypt, were excavated mainly in the calcarenitic limestone formations and show varying degrees of damage of rock pillars and ceilings. In order to understand the long-term rock mass behaviour in selected tombs and its impact on past failures and current stability, uniaxial and triaxial Creep tests and rock mass quality assessments had been carried out. Creep behavior of rock plays an important role in underground works, especially for archeological structures subjected to large initial stresses. These conditions yield nonreversible deviatoric creep strains that develop during time at constant stress. In order to describe the time-dependent deformation, various approaches have been established based on analytical, empirical, and numerical methods. Our analyses show that the Roman tombs at Alexandria have been cut into poor quality rock masses. Rock failures of ceilings and pillars were frequently facilitated by local, unfavourably oriented persistent discontinuities, such as tension cracks and joints. Other failures were related to the disintegration of calcarenitic and oolitic lime-stones. Our data suggest that, in Roman age monumental tomb construction, low-strength rock masses resulted in modifications of the planned tomb design in order to minimise the risk of rock falls and to prevent collapses.
{"title":"Uniaxial and Triaxial Creep Performance of Calcarenitic and Sandy Oolitic Limestone Formations for Stability Analysis of Roman Rock-Cut Tombs in Alexandria, Egypt","authors":"S. Hemeda","doi":"10.5772/intechopen.91720","DOIUrl":"https://doi.org/10.5772/intechopen.91720","url":null,"abstract":"The Greek-Roman rock-cut tombs at Alexandria, Egypt, were excavated mainly in the calcarenitic limestone formations and show varying degrees of damage of rock pillars and ceilings. In order to understand the long-term rock mass behaviour in selected tombs and its impact on past failures and current stability, uniaxial and triaxial Creep tests and rock mass quality assessments had been carried out. Creep behavior of rock plays an important role in underground works, especially for archeological structures subjected to large initial stresses. These conditions yield nonreversible deviatoric creep strains that develop during time at constant stress. In order to describe the time-dependent deformation, various approaches have been established based on analytical, empirical, and numerical methods. Our analyses show that the Roman tombs at Alexandria have been cut into poor quality rock masses. Rock failures of ceilings and pillars were frequently facilitated by local, unfavourably oriented persistent discontinuities, such as tension cracks and joints. Other failures were related to the disintegration of calcarenitic and oolitic lime-stones. Our data suggest that, in Roman age monumental tomb construction, low-strength rock masses resulted in modifications of the planned tomb design in order to minimise the risk of rock falls and to prevent collapses.","PeriodicalId":66124,"journal":{"name":"土工基础","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86021496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-12-13DOI: 10.5772/intechopen.85549
H. Elosta
The touchdown zone (TDZ) often proves to be a spot where cyclic bending stresses are the largest and is therefore a critical location for fatigue. Catenary steel compliant pipelines or risers (SCRs) are subject of much ongoing research, particularly with respect to their fatigue life, which is strongly influenced by seabed soil conditions in the TDZ. This chapter reviews the recent publications that might have an impact on the SCR-seabed interaction. The review starts by looking at the SCR general arrangement. Thereafter, the focus moves to the review of the recent research that studied the interactions between deepwater SCRs and the seabed. In addition, thereview went over the analysis techniques of the SCR, including the modelling philosophy and models for geotechnical response. The research gap and the need for future research are identified.
{"title":"Geotechnical Response Models for Steel Compliant Riser in Deepwater Clays","authors":"H. Elosta","doi":"10.5772/intechopen.85549","DOIUrl":"https://doi.org/10.5772/intechopen.85549","url":null,"abstract":"The touchdown zone (TDZ) often proves to be a spot where cyclic bending stresses are the largest and is therefore a critical location for fatigue. Catenary steel compliant pipelines or risers (SCRs) are subject of much ongoing research, particularly with respect to their fatigue life, which is strongly influenced by seabed soil conditions in the TDZ. This chapter reviews the recent publications that might have an impact on the SCR-seabed interaction. The review starts by looking at the SCR general arrangement. Thereafter, the focus moves to the review of the recent research that studied the interactions between deepwater SCRs and the seabed. In addition, thereview went over the analysis techniques of the SCR, including the modelling philosophy and models for geotechnical response. The research gap and the need for future research are identified.","PeriodicalId":66124,"journal":{"name":"土工基础","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74991005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-08-26DOI: 10.5772/intechopen.88682
K. B. Afacan
Recent studies about liquefaction initiation are widely encountered in the literature in terms of utilizing the dynamic triaxial tests under harmonic loading and site response of liquefied zones. Sandy-like or clayey-like behavior is important for estimating the liquefaction susceptibility but there are other factors related to cyclic loading characteristics such as frequency content and stress level. Besides, 1-D ground response analyses are employed to understand the behavioral transmission through the soil column in liquefiable areas. The study here focuses on two main aspects of the liquefaction. The first part consists of the estimating of the pore pressure generation under irregular excitations, whereas the second part aims to assess the efficiency of the building codes predicting the nonlinear site response in liquefied prone areas. The laboratory results show that the frequency content has big influence on the liquefaction at varying stress levels. Moreover, literature models have discrepancies to estimate the pore pressure generation under different types of loading. Regarding the site response, it was indicated that equivalent linear approach is incapable of predicting the seismic behavior of soil column; therefore, nonlinear ground response must be run instead, and the IBC is the most effective one to match the nonlinear analysis results.
{"title":"Estimation of Excess Pore Pressure Generation and Nonlinear Site Response of Liquefied Areas","authors":"K. B. Afacan","doi":"10.5772/intechopen.88682","DOIUrl":"https://doi.org/10.5772/intechopen.88682","url":null,"abstract":"Recent studies about liquefaction initiation are widely encountered in the literature in terms of utilizing the dynamic triaxial tests under harmonic loading and site response of liquefied zones. Sandy-like or clayey-like behavior is important for estimating the liquefaction susceptibility but there are other factors related to cyclic loading characteristics such as frequency content and stress level. Besides, 1-D ground response analyses are employed to understand the behavioral transmission through the soil column in liquefiable areas. The study here focuses on two main aspects of the liquefaction. The first part consists of the estimating of the pore pressure generation under irregular excitations, whereas the second part aims to assess the efficiency of the building codes predicting the nonlinear site response in liquefied prone areas. The laboratory results show that the frequency content has big influence on the liquefaction at varying stress levels. Moreover, literature models have discrepancies to estimate the pore pressure generation under different types of loading. Regarding the site response, it was indicated that equivalent linear approach is incapable of predicting the seismic behavior of soil column; therefore, nonlinear ground response must be run instead, and the IBC is the most effective one to match the nonlinear analysis results.","PeriodicalId":66124,"journal":{"name":"土工基础","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74003416","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-08-20DOI: 10.5772/INTECHOPEN.88591
W. Qi, F. Gao
Monopile is the most commonly used foundation type for offshore wind turbines. The local scour at a monopile foundation generated by the incoming shear flow has significant influence on both quasi-static lateral responses and dynamic responses of the monopile. This chapter focuses particularly on characterizing the local scour in both spatial and temporal scales and revealing the scour mechanisms associated with the flow field around a monopile. The predicting methods for the equilibrium scour depth and the time scale of scour are detailed under various representative flow conditions in the marine environment. The scale effect while extrapolating the results of model tests to prototype conditions is highlighted. The local scour imposes significant influence not only on the deformation and stiffness of the monopile foundation, but also on the natural frequency and fatigue life of the structure system. Monopiles with diameters up to 10 m have become a feasible option as the industry is currently advancing into deeper waters. More meticulous considerations for monopile design associated with the scour depth prediction and evaluation of scour effects are still in need to efficiently minimize the cost while remaining safety simultaneously.
{"title":"Local Scour around a Monopile Foundation for Offshore Wind Turbines and Scour Effects on Structural Responses","authors":"W. Qi, F. Gao","doi":"10.5772/INTECHOPEN.88591","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.88591","url":null,"abstract":"Monopile is the most commonly used foundation type for offshore wind turbines. The local scour at a monopile foundation generated by the incoming shear flow has significant influence on both quasi-static lateral responses and dynamic responses of the monopile. This chapter focuses particularly on characterizing the local scour in both spatial and temporal scales and revealing the scour mechanisms associated with the flow field around a monopile. The predicting methods for the equilibrium scour depth and the time scale of scour are detailed under various representative flow conditions in the marine environment. The scale effect while extrapolating the results of model tests to prototype conditions is highlighted. The local scour imposes significant influence not only on the deformation and stiffness of the monopile foundation, but also on the natural frequency and fatigue life of the structure system. Monopiles with diameters up to 10 m have become a feasible option as the industry is currently advancing into deeper waters. More meticulous considerations for monopile design associated with the scour depth prediction and evaluation of scour effects are still in need to efficiently minimize the cost while remaining safety simultaneously.","PeriodicalId":66124,"journal":{"name":"土工基础","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73727249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-06-17DOI: 10.5772/INTECHOPEN.86430
Xirong Niu
A great deal of weathered granite soils are distributed in mountainous areas around the world. With further improvements to the civil engineering, more and more construction infrastructures (roads, railways, dams, etc.) in mountainous areas will be built. Making full use of weathered granite soils, a type of special geomaterial, can alleviate the shortage of building materials in mountainous areas. Weathered granite soil has its own unique physical and mechanical properties, e.g., disintegrative, easy weathering, and particle breakage. In this chapter, a large number of field investigations and laboratory tests (including X-ray diffraction, sieving, heavy compaction, and large-scale triaxial) have been carried out. The process of weathering, the influence factors on particle breakage, and the mechanical properties of compacted weathered granite have been discussed. The results show that particle gradation, mineral content, blows per layer, and stress level have a significant effect on the particle breakage characteristics of weathered granite soils. The experimental results show that the product of the stress ratio at shear failure M f and the stress ratio at characteristic state point M c is not a constant but a power function of an average main stress p due to particle breakage. Hereby, the constitutive model of weathered granite soils was proposed.
{"title":"Weathered Granite Soils","authors":"Xirong Niu","doi":"10.5772/INTECHOPEN.86430","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.86430","url":null,"abstract":"A great deal of weathered granite soils are distributed in mountainous areas around the world. With further improvements to the civil engineering, more and more construction infrastructures (roads, railways, dams, etc.) in mountainous areas will be built. Making full use of weathered granite soils, a type of special geomaterial, can alleviate the shortage of building materials in mountainous areas. Weathered granite soil has its own unique physical and mechanical properties, e.g., disintegrative, easy weathering, and particle breakage. In this chapter, a large number of field investigations and laboratory tests (including X-ray diffraction, sieving, heavy compaction, and large-scale triaxial) have been carried out. The process of weathering, the influence factors on particle breakage, and the mechanical properties of compacted weathered granite have been discussed. The results show that particle gradation, mineral content, blows per layer, and stress level have a significant effect on the particle breakage characteristics of weathered granite soils. The experimental results show that the product of the stress ratio at shear failure M f and the stress ratio at characteristic state point M c is not a constant but a power function of an average main stress p due to particle breakage. Hereby, the constitutive model of weathered granite soils was proposed.","PeriodicalId":66124,"journal":{"name":"土工基础","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90231803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-04-09DOI: 10.5772/INTECHOPEN.82575
Yangsheng Ye, Xiaoyan Du, Qianli Zhang, Jinfei Chai
With the rapid development of high-speed railway, high-speed railways pose new requirements on subgrade frost heave deformation control. Microheave in conventional non-frost-heave filler cannot meet the requirements of high-speed railways for high levels of smoothness and stability and threaten high-speed train operation safety. To solve problems of seasonal permafrost region subgrade filler microheave in China, combined laboratory test and theoretical analysis, this research analyzed the physical properties of frost heave influencing factors for microheave filler. The influence of skeleton grain during frost heave formation is revealed. The microheave filler frost heave development mechanism is investigated. On this basis, based on the principle of minimum energy, a frost heave calculation formula for microheave filler is deduced, and a frost heave deformation analysis model for microheave filler is created. In addition, the effectiveness of the model is demonstrated in an indoor test. This study provides a theoretical reference for controlling the frost heaving deformation of railway subgrade.
{"title":"Frost Heave Deformation Analysis Model for Microheave Filler","authors":"Yangsheng Ye, Xiaoyan Du, Qianli Zhang, Jinfei Chai","doi":"10.5772/INTECHOPEN.82575","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.82575","url":null,"abstract":"With the rapid development of high-speed railway, high-speed railways pose new requirements on subgrade frost heave deformation control. Microheave in conventional non-frost-heave filler cannot meet the requirements of high-speed railways for high levels of smoothness and stability and threaten high-speed train operation safety. To solve problems of seasonal permafrost region subgrade filler microheave in China, combined laboratory test and theoretical analysis, this research analyzed the physical properties of frost heave influencing factors for microheave filler. The influence of skeleton grain during frost heave formation is revealed. The microheave filler frost heave development mechanism is investigated. On this basis, based on the principle of minimum energy, a frost heave calculation formula for microheave filler is deduced, and a frost heave deformation analysis model for microheave filler is created. In addition, the effectiveness of the model is demonstrated in an indoor test. This study provides a theoretical reference for controlling the frost heaving deformation of railway subgrade.","PeriodicalId":66124,"journal":{"name":"土工基础","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91213939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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