Geotechnical Engineering 3
Computational Modelling Assignment
Coursework brief for ComputaConal Modelling
2024 -2025 Academic Year
Please read the following instrucCons carefully
InstrucCons for submission: Please submit the following required files and documents; the deadline for submission is 23:59 Wednesday 22nd December 2024 via Canvas. You will be penalised if you submit late (5% per working day). Each group needs to submit three files. You are advised to aDempt the exercise as soon as possible and prepare your report well before the deadline. Peer assessment is available (see below) and will be used to adjust final marks by no more than plus/minus 10%, to reflect an assessment of contribuKons across the group. All peer assessments are subject to final moderaKon by the module delivery team. If you do not submit a peer assessment, every team member will be given the same mark.
The first file is a professional report of maximum 10 pages excluding Ktle page, contents, list of figures, list of tables, nomenclature, and references/bibliography – NO appendices are allowed (you will lose 5% per page over the limit). Submit the report file in PDF format. It is recommended to type the report using a word processing soSware e.g., MicrosoS Word, Latex. The report should be singled line, font Arial, minimum font size 11, and minimum margins of 2 cm from top, boDom, leS and right. On the Ktle page of your report, you must clearly add the name of the group members, your group number, and the following phrase followed by signatures from all members, “We are aware of and understand the University’s policy on plagiarism and we cer:fy that this assignment is our own work, except where indicated by referencing, and that we have followed good academic prac:ces” . Submissions without Ctle page as set out will not be considered and any subsequent delays will be count to late penalty marks.
The second file of your submission is your ABAQUS files (both *.cae and *.inp). Please note that in total there are two ABAQUS simulaKons (one for Part 1 and one for Part 2). Each file size cannot exceed 6 MB. Only one member of the group needs to submit the required files. Group numbers and members are allocated separately. The file names should only contain the group number and the ABAQUS files should contain both the group number and the Part number separated by an underline. For example, group ‘23’ will submit five files of ‘23_P1.inp’, ‘23_P1.cae’, ‘23_P2.inp’, ‘23_P2.cae’ and ‘23.pdf’. Each group has a unique set of values for the parameters and so please make sure you choose the correct values otherwise you will lose marks. If you have any quesKons, please contact Prof Asaad Faramarzi ([email protected]).
AllocaCon of marks:
• Quality of the report including overall wri:ng, English, presenta:on, referencing: 15%
• Results, and discussions: 50%
• Numerical modelling: 35%
Ques&on (Pile-Tunnel Interac&on):
Introduc)on:
Twenty-five years ago, the Mass Rapid Transit system called the North-East Line (NEL) was constructed in Singapore to improve public transportaKon connecKvity and cater to the growing populaKon in the north-eastern region of the country. However, during construcKon, the engineers faced a significant challenge, as the bored tunnelling acKviKes had to be carried out unavoidably close to the foundaKon of an exisKng flyover bridge. At the Kme, the government expressed concerned about the potenKal to impact of the tunnelling on the bridge’s foundaKon. As a result, numerous instruments were installed to monitor the foundaKon in order to observe any potenKal impacts. Strain gauges, seDlement points, and inclinometers were installed on the piles to monitor the addiKonal forces, seDlement, and horizontal movement of the piles, respecKvely. During tunnelling, a volume loss of 1.38% was observed as the tunnel passed beneath the foundaKon. The pile head seDlement was observed at 2.43 mm aSer tunnel passed through. Water table remains constant throughout the project at 3m below ground surface for both exisKng and the future tunnel construcKon. Figure 1 illustrates the other observed impact on the piles caused by the tunnelling acKviKes.
Recently, the TransportaKon Authority of Singapore has planned to construct a new metro line. This new metro line will be built close to the exisKng NEL. Unfortunately, due to limited construcKon space, the upcoming bored tunnelling will need to be carried out near the exisKng piled foundaKon of Pier No.23 (see Plan View). However, this Kme, the government has strictly stated that the impact on the exisKng piles must be minimised. In response to this, alternaKve construcKon approaches have been proposed by engineers, including reducing volume loss, adjusKng the tunnel alignment verKcally and horizontally, and reducing tunnel diameter.
As the engineer responsible for this project, you are required to conduct the following analysis and discuss the results. As a first step towards the necessary analysis, it is important to validate the FE analysis. This is oSen done through simulaKng an exisKng scenario which in this case can be the exisKng tunnel of Pier No . 20 and the data obtained from the instrumentaKon . As such, the following are expected to be completed:
Part 1) To validate your FE analysis, create a 2D model (plane strain) of the exisKng tunnel (note Figure 2 and Figure 3) and compare the results with the graphs given above in Figure 1. Discuss any assumpKons you have made in your FE and the results in the context of accuracy and reliability. The geometry of the problem, as well as the geological soil profiles and parameters, can be found in the figures and tables below. For further informaKon, please see Pang 2006 thesis document available on CANVAS.
Part 2) To develop an FE model for the new tunnelling line (Figure 4) based on the parameters relevant to your group and discuss the results in terms of accuracy and reliability. Also, discuss the results in the context of the miKgaKon approach taken and the impacts they may have on the ‘pile horizontal movement’, ‘induced axial force’, and ‘induced bending moment’.