Tunnel boring machines require extensive maintenance and inspection effort to provide a high availability.The cutting tools of the cutting wheel must be changed timely upon reaching a critical condition.While one poss...Tunnel boring machines require extensive maintenance and inspection effort to provide a high availability.The cutting tools of the cutting wheel must be changed timely upon reaching a critical condition.While one possible maintenance strategy is to change tools only when it is absolutely necessary,tools can also be changed preventively to avoid further damages.Such different maintenance strategies influence the maintenance duration and the overall project performance.However,determine downtime related to a particular mainte-nance strategy is still a challenging task.This paper shows an analysis of the robustness to achieve the planned project performance of a maintenance strategy considering uncertainties of wear behavior of the cutting tools.A simulation based analysis is presented,imple-menting an empirical wear prediction model.Different strategies of maintenance planning are compared by performing a parameter vari-ation study including Monte-Carlo simulations.The maintenance costs are calculated and evaluated with respect to their robustness.Finally,an improved and robust maintenance strategy has been determined.展开更多
The development of digital transformation in the construction industry has led to the increasing adoption of smart contracts.As programmable applications to automatically write,verify,and enforce transaction condition...The development of digital transformation in the construction industry has led to the increasing adoption of smart contracts.As programmable applications to automatically write,verify,and enforce transaction conditions,smart contracts can be used in different areas mainly to improve automation level,information security,and built digital environment enhancement.However,the smart contract is commonly mentioned as a blockchain appendage,while its unique connotation and value in the construction industry have not been recognized.Therefore,this study carries out a systematic review based on 81 research articles published from 2014 to 2021 on smart contract applications in construction to explore and highlight their potentials under domain-specific requirements.Results are analyzed according to research type categorization and domain codification.Eight research domains are identified,where the three most highly explored domains are contract and payment,supply chain and logistics,and information management.The integration of smart contracts with other innovative concepts and advanced technologies is analyzed.The applicability,benefits,and challenges of smart contract applications regarding different research domains are discussed.展开更多
When performing shallow tunnel construction,settlements on the ground surface often cannot be prevented.Anticipating these sur-face displacements is only possible with profound knowledge of the constitutive parameters...When performing shallow tunnel construction,settlements on the ground surface often cannot be prevented.Anticipating these sur-face displacements is only possible with profound knowledge of the constitutive parameters of the surrounding soil.Performing inverse analysis on the basis of in situ settlement data is an effcient method for obtaining such information.However,during this process,con-sidering which measurement arrangement can provide the most reliable results is generally neglected.This aspect is addressed in this study by applying the so-called“optimal experimental design”to the mechanized tunnelingfield.A global sensitivity analysis(GSA)isfirstly performed to determine the most relevant model parameters to be identified via back analysis,by employing the considered numerical model and experimental data.Furthermore,the GSA results are utilized to determine where and when measurements should be performed to minimize uncertainty in the identified constitutive parameters.The optimal experimental design(OED)concept is fur-ther applied to evaluate the observation set-up effciency for damage mitigation measures within a representative synthetic example of a tunneling project passing beneath an existing building.Parameter identification based on synthetic noisy experiments is performed to validate the presented method for optimal experimental design.Thus,the soil stiffness and strength parameters are identified according to both an intuitive and the elaborated method,employing the proposed OED strategy and experimental designs,making it possible to assess the feasibility of the OED results.展开更多
基金the Deutsche Forschungsgemeinschaft (grant SFB 410)the German-Israeli Foundation for Scientific Research and Development (grant 881/05)+4 种基金the NSF(grant DMR-0342832)the U.S.Department of EnergyOffice of Basic Energy Sciencesunder contract DE-AC03-76SF00515Focus Center Research Program (FCRP) Center on Functional Engineered Nanoarchitectonics (FENA)
文摘Tunnel boring machines require extensive maintenance and inspection effort to provide a high availability.The cutting tools of the cutting wheel must be changed timely upon reaching a critical condition.While one possible maintenance strategy is to change tools only when it is absolutely necessary,tools can also be changed preventively to avoid further damages.Such different maintenance strategies influence the maintenance duration and the overall project performance.However,determine downtime related to a particular mainte-nance strategy is still a challenging task.This paper shows an analysis of the robustness to achieve the planned project performance of a maintenance strategy considering uncertainties of wear behavior of the cutting tools.A simulation based analysis is presented,imple-menting an empirical wear prediction model.Different strategies of maintenance planning are compared by performing a parameter vari-ation study including Monte-Carlo simulations.The maintenance costs are calculated and evaluated with respect to their robustness.Finally,an improved and robust maintenance strategy has been determined.
基金This study was carried out as part of the BIMcontracts research project funded by the German Federal Ministry for Economic Affairs and Energy(BMWi)within the“Smart Data Economy”technology program(Grant No.01MD19006B).
文摘The development of digital transformation in the construction industry has led to the increasing adoption of smart contracts.As programmable applications to automatically write,verify,and enforce transaction conditions,smart contracts can be used in different areas mainly to improve automation level,information security,and built digital environment enhancement.However,the smart contract is commonly mentioned as a blockchain appendage,while its unique connotation and value in the construction industry have not been recognized.Therefore,this study carries out a systematic review based on 81 research articles published from 2014 to 2021 on smart contract applications in construction to explore and highlight their potentials under domain-specific requirements.Results are analyzed according to research type categorization and domain codification.Eight research domains are identified,where the three most highly explored domains are contract and payment,supply chain and logistics,and information management.The integration of smart contracts with other innovative concepts and advanced technologies is analyzed.The applicability,benefits,and challenges of smart contract applications regarding different research domains are discussed.
文摘When performing shallow tunnel construction,settlements on the ground surface often cannot be prevented.Anticipating these sur-face displacements is only possible with profound knowledge of the constitutive parameters of the surrounding soil.Performing inverse analysis on the basis of in situ settlement data is an effcient method for obtaining such information.However,during this process,con-sidering which measurement arrangement can provide the most reliable results is generally neglected.This aspect is addressed in this study by applying the so-called“optimal experimental design”to the mechanized tunnelingfield.A global sensitivity analysis(GSA)isfirstly performed to determine the most relevant model parameters to be identified via back analysis,by employing the considered numerical model and experimental data.Furthermore,the GSA results are utilized to determine where and when measurements should be performed to minimize uncertainty in the identified constitutive parameters.The optimal experimental design(OED)concept is fur-ther applied to evaluate the observation set-up effciency for damage mitigation measures within a representative synthetic example of a tunneling project passing beneath an existing building.Parameter identification based on synthetic noisy experiments is performed to validate the presented method for optimal experimental design.Thus,the soil stiffness and strength parameters are identified according to both an intuitive and the elaborated method,employing the proposed OED strategy and experimental designs,making it possible to assess the feasibility of the OED results.
