By using site observation data and establishing 3D model using ANSYS software, this paper has discussed the strain change of stratum stress during process of jacking-in and the impact of machine head on ground surface...By using site observation data and establishing 3D model using ANSYS software, this paper has discussed the strain change of stratum stress during process of jacking-in and the impact of machine head on ground surface under different frontal resistances. Analysis of the two cases shows that soil pressure reaches its maximum point when the soil is right above machine head, and soil stress will gradually decline when machine head passes over it. It also shows that impact brought by pipe-jacking construction on stress change of the surrounding soil is limited. The thesis suggest that road surface should be consolidated and soil condition be improved before construction to prevent loss and disaster caused by road surface deformation, jacking force can be increased so that jacking efficiency can be enhanced when ground stratum is well filled with soil, but the frontal resistance facing machine head should be equal to surrounding soil pressure in order to avoid rise of ground surface.展开更多
So many potential risks can be identifed for application of trenchless technology especially using microtunneling methods.Unexpected changes in ground conditions,such as encountering boulders,tree roots,ground water a...So many potential risks can be identifed for application of trenchless technology especially using microtunneling methods.Unexpected changes in ground conditions,such as encountering boulders,tree roots,ground water and man-made structures such as old foundations are the principal geotechnical risks,which affect the selection of an appropriate microtunnel boring machine.On the other hand,the performance of each microtunneling technique will differ while encountering such conditions.Hence,predicting the potential hazards provides a better safety and risk management plan.In this study,a couple of potentially hazardous situation,which are commonly associated with ground conditions,were identifed and investigated.A decision tree aid methodology was proposed based on geotechnical risk assessment for selection of proper microtunneling technique.Based on the approach the most appropriate microtunneling technique has the minimum risk level either before or after hazards mitigation measures.In order to check the effciency of the approach in practice,selection of microtunnel boring machine for Hamadan sewerage pipeline project was evaluated.Accordingly,an earth pressure balance(EPB)MTBM was selected for the project.展开更多
Currently,there is a worldwide trend towards reducing emissions into the environment generated by human activities.Pollutant emissions into the atmosphere are a major measure of the impact on environment.The construct...Currently,there is a worldwide trend towards reducing emissions into the environment generated by human activities.Pollutant emissions into the atmosphere are a major measure of the impact on environment.The construction indus-try is a major producer of such emissions due in part to the magnitude of operations and the vast array of equipment.Increased urbanization has resulted in a need for the installation of an expanded underground network of infrastruc-ture that includes gas,water,wastewater,pipelines,power,and communications systems.Today,engineers are faced with engaging the construction option that not only provides the best cost advantage,but also considers environmental sensitivities to create the most sustainable solution.Reduction of pollutants such as carbon dioxide(CO_(2)),carbon monoxide(CO),nitrogen oxide(NO_(X)),total organic compounds(TOC),and sulfur oxide(SO_(X))have been identified by the United States Environmental Protection Agency as critical to sustainable development.This paper describes an approach for quantifying airborne emissions that is demonstrated through a comparison of two construction methods for installing a wastewater line.It was discovered that the option involving a traditional open cut method resulted in an overall average of about 80%greater emissions compared to trenchless pipe replacement.Thefindings of this paper should assist the utility construction industry in technology selection to minimize environmental impacts.展开更多
Corrosion is one of the most common forms of damage to pressure pipes.CIPP liner can improve the mechanical properties of the pipe with corrosion.It is very important to study the mechanical response of corrosion pipe...Corrosion is one of the most common forms of damage to pressure pipes.CIPP liner can improve the mechanical properties of the pipe with corrosion.It is very important to study the mechanical response of corrosion pipes rehabilitated by CIPP liner.In this study,a three-dimensional finite element model of a pressure pipe rehabilitated with CIPP liner under the condition of circular corrosion is established,and the model is evaluated by using the experimental and analytical results.Afterward,the influence of each parameter on the stress and displacement of the liner is analyzed.Finally,the liner stress calculation equation is obtained based on 870 sets of data.The results show that the finite element results are in good agreement with the experimental and analytical results.The maximum stress of the liner first occurs at the center of the corroded circle,and as the corrosion diameter increases,the maximum stress gradually shifts to the edge.The maximum stress of the liner increases first and then tends to be stable with the increase of the corrosion diameter,and the friction coefficient has little effect on the liner stress.展开更多
Reinforced concrete pipes(RCPs)were commonly used in older underground pipelines in Taiwan,China.However,their joints are prone to damage,including fracture and separation,from problems such as overloading,poor backfi...Reinforced concrete pipes(RCPs)were commonly used in older underground pipelines in Taiwan,China.However,their joints are prone to damage,including fracture and separation,from problems such as overloading,poor backfilling,and liquefaction.For the rehabilitation of such aged pipelines,trenchless methods are preferred to minimize the impact on transportation.The cured-in-place-pipe(CIPP)rehabilitation could be one of the most popular trenchless methods suitable for the cases with angular alignment and changing cross-section.However,according to the existing standards,no details are available on the performance of the rehabilitated parts of the damaged pipeline,including the effect of separated joint.This study designed and conducted laboratory testing on the composite pipe joint(the CIPP rehabilitated RCPs with a separated joint)with different scenarios,including radial and longitudinal loading tests.The radial test results indicated that,for a small separation distance,CIPP rehabilitation can restore the original function of a pipeline and improve its hoop strength.The longitudinal test revealed that the damage due to bending was controlled by the tensile strength of the liner material.The ultimate flexural strength decreased as the separation distance increased.However,pipelines may be subjected to additional loads due to flotation or subsidence,for which the longitudinal loading capacity is often the limiting parameter.For such conditions,it is necessary to confirm,by more research,whether the wall thickness is sufficient.展开更多
基金the Science and Technology Foundation of Sichuan Department of Land and Resources(SCDLR0609)
文摘By using site observation data and establishing 3D model using ANSYS software, this paper has discussed the strain change of stratum stress during process of jacking-in and the impact of machine head on ground surface under different frontal resistances. Analysis of the two cases shows that soil pressure reaches its maximum point when the soil is right above machine head, and soil stress will gradually decline when machine head passes over it. It also shows that impact brought by pipe-jacking construction on stress change of the surrounding soil is limited. The thesis suggest that road surface should be consolidated and soil condition be improved before construction to prevent loss and disaster caused by road surface deformation, jacking force can be increased so that jacking efficiency can be enhanced when ground stratum is well filled with soil, but the frontal resistance facing machine head should be equal to surrounding soil pressure in order to avoid rise of ground surface.
文摘So many potential risks can be identifed for application of trenchless technology especially using microtunneling methods.Unexpected changes in ground conditions,such as encountering boulders,tree roots,ground water and man-made structures such as old foundations are the principal geotechnical risks,which affect the selection of an appropriate microtunnel boring machine.On the other hand,the performance of each microtunneling technique will differ while encountering such conditions.Hence,predicting the potential hazards provides a better safety and risk management plan.In this study,a couple of potentially hazardous situation,which are commonly associated with ground conditions,were identifed and investigated.A decision tree aid methodology was proposed based on geotechnical risk assessment for selection of proper microtunneling technique.Based on the approach the most appropriate microtunneling technique has the minimum risk level either before or after hazards mitigation measures.In order to check the effciency of the approach in practice,selection of microtunnel boring machine for Hamadan sewerage pipeline project was evaluated.Accordingly,an earth pressure balance(EPB)MTBM was selected for the project.
文摘Currently,there is a worldwide trend towards reducing emissions into the environment generated by human activities.Pollutant emissions into the atmosphere are a major measure of the impact on environment.The construction indus-try is a major producer of such emissions due in part to the magnitude of operations and the vast array of equipment.Increased urbanization has resulted in a need for the installation of an expanded underground network of infrastruc-ture that includes gas,water,wastewater,pipelines,power,and communications systems.Today,engineers are faced with engaging the construction option that not only provides the best cost advantage,but also considers environmental sensitivities to create the most sustainable solution.Reduction of pollutants such as carbon dioxide(CO_(2)),carbon monoxide(CO),nitrogen oxide(NO_(X)),total organic compounds(TOC),and sulfur oxide(SO_(X))have been identified by the United States Environmental Protection Agency as critical to sustainable development.This paper describes an approach for quantifying airborne emissions that is demonstrated through a comparison of two construction methods for installing a wastewater line.It was discovered that the option involving a traditional open cut method resulted in an overall average of about 80%greater emissions compared to trenchless pipe replacement.Thefindings of this paper should assist the utility construction industry in technology selection to minimize environmental impacts.
基金supported by the National Natural Science Foundation of China(no.52309174,52208375)the National Postdoctoral Program for Innovative Talents(no.BX20230328)the China Postdoctoral Science Foundation(no.2023M743219,2022M722884).
文摘Corrosion is one of the most common forms of damage to pressure pipes.CIPP liner can improve the mechanical properties of the pipe with corrosion.It is very important to study the mechanical response of corrosion pipes rehabilitated by CIPP liner.In this study,a three-dimensional finite element model of a pressure pipe rehabilitated with CIPP liner under the condition of circular corrosion is established,and the model is evaluated by using the experimental and analytical results.Afterward,the influence of each parameter on the stress and displacement of the liner is analyzed.Finally,the liner stress calculation equation is obtained based on 870 sets of data.The results show that the finite element results are in good agreement with the experimental and analytical results.The maximum stress of the liner first occurs at the center of the corroded circle,and as the corrosion diameter increases,the maximum stress gradually shifts to the edge.The maximum stress of the liner increases first and then tends to be stable with the increase of the corrosion diameter,and the friction coefficient has little effect on the liner stress.
基金the financial support of the Science and Technology authority of Taiwan,China(Project No.109-2622-E-005-014).
文摘Reinforced concrete pipes(RCPs)were commonly used in older underground pipelines in Taiwan,China.However,their joints are prone to damage,including fracture and separation,from problems such as overloading,poor backfilling,and liquefaction.For the rehabilitation of such aged pipelines,trenchless methods are preferred to minimize the impact on transportation.The cured-in-place-pipe(CIPP)rehabilitation could be one of the most popular trenchless methods suitable for the cases with angular alignment and changing cross-section.However,according to the existing standards,no details are available on the performance of the rehabilitated parts of the damaged pipeline,including the effect of separated joint.This study designed and conducted laboratory testing on the composite pipe joint(the CIPP rehabilitated RCPs with a separated joint)with different scenarios,including radial and longitudinal loading tests.The radial test results indicated that,for a small separation distance,CIPP rehabilitation can restore the original function of a pipeline and improve its hoop strength.The longitudinal test revealed that the damage due to bending was controlled by the tensile strength of the liner material.The ultimate flexural strength decreased as the separation distance increased.However,pipelines may be subjected to additional loads due to flotation or subsidence,for which the longitudinal loading capacity is often the limiting parameter.For such conditions,it is necessary to confirm,by more research,whether the wall thickness is sufficient.
