{"title":"Numerical modeling of optimum spacing of TBM disk cutters, using a finite element method simulation","authors":"Mohammadreza Faraji Tilehnoei, Kourosh Shahriar, Hassan Madani","doi":"10.1002/geot.202300017","DOIUrl":"https://doi.org/10.1002/geot.202300017","url":null,"abstract":"Due to the growing demand for underground communication methods, water transfer, and utility tunnels, employing mechanized tunneling methods is unavoidable. Diverse disk cutters are built and operated. A proper cutterhead design will have a direct impact on the net advance rate and therefore significantly contribute to the project success. The research effort presented in this contribution is dealing with the spacing effect on the forces on disk cutters, and their specific energy (SE) has been investigated. It uses finite element numerical modeling with ABAQUS software to simulate the rock‐cutting process to find an optimal spacing in barre granite. The results show that theratio of the disk spacing to the penetration rate, the normal and rotational forces on the disk cutters, and the SE values increase to the optimal level and then decrease. The optimal spacing for the examined rock type is discussed in further detail, and a recommendation for the optimum cutterhead layout is presented.","PeriodicalId":507260,"journal":{"name":"Geomechanics and Tunnelling","volume":"7 19","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141363285","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}
Thomas Roper, Robert Bertuzzi, David Oliveira, Jurij Karlovšek
{"title":"A framework to demonstrate the utility and safety of the observational method","authors":"Thomas Roper, Robert Bertuzzi, David Oliveira, Jurij Karlovšek","doi":"10.1002/geot.202300041","DOIUrl":"https://doi.org/10.1002/geot.202300041","url":null,"abstract":"Underground engineering projects are often characterised by significant uncertainties, leading to complex decision‐making when selecting appropriate design methods. Traditional approaches, such as the observational method (OM), have been widely used but rarely explicitly account for the integration of risk, costs, construction timeframes and engineering judgement. Successfully reaching a consensus to implement the OM on tunnelling projects can be challenging and requires ensuring stakeholders understand how the method impacts structural safety. Fostering such understanding can be an arduous process. A risk‐based decision framework is introduced using expected utility theory to aid the decision to choose the OM, or not. The framework integrates risk, cost, construction timelines and engineering judgement within an economic decision model using a probabilistic approach. It is tested on a Sydney, Australia case study. A Monte Carlo model analysis examines contingency actions and structural failure probability when applying the OM. The case study highlights the significance of considering indirect costs in complex decisions and harnesses experienced professionals’ insights for a comprehensive risk and cost assessment. We conclude that merging probabilistic‐based design with OM enhances the ability to demonstrate structural safety and economic factors within a unified model.","PeriodicalId":507260,"journal":{"name":"Geomechanics and Tunnelling","volume":"75 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139780306","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}