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The PLAXIS Tunnelling Library

Are you interested in gaining more knowledge about Tunnel modelling in PLAXIS? Are tunnel excavations in rock, NATM, TBM, PLAXIS Tunnel designer of your point of interest? Then this blog is the perfect resource for you to start and explore the PLAXIS tunnelling world.

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The PLAXIS Tunnel Engineer’s toolbox: everything you will need in one place 

This blog is a part of the series Tunnel your way to success with PLAXIS. PLAXIS offers a wide range of tools to the Tunnel Engineer, which can be combined to generate almost any ground, tunnel, and reinforcement system geometry. Node-to-node anchors  As their name indicates, node-to-node anchors provide an elastic connection between two non-adjacent nodes. These line elements only interact with the finite element mesh at their end nodes, which makes them especially indicated for modelling the free (unbonded) length of ground reinforcements.  Embedded beams  Contrary to the node-to-node anchors, embedded beams are… well, embedded. They are elastically connected to the ground along their whole length, and at the bottom. Thus, they can model almost any reinforcement element: piles and micropiles, dowels, rockbolts, forepoles, etc. They can also be connected to the end of a node-to-node anchor to model the grouted (bonded) partition of any discontinuously coupled reinforcement. Embedded beams cannot be prestressed, but node-to-node anchors can, so their combination can be prestressed through the node-to-node and transmit those stresses to the ground through the embedded beam.    Cables  If you could mix a node-to-node anchor and an embedded beam, you would get a cable. Cables are line elements that

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Rock your underground construction with PLAXIS 

This blog is a part of the series Tunnel your way to success with PLAXIS. Underground construction is a complex endeavour. Leveraging rock masses as engineering materials requires overcoming many challenges. Any work needs to be carried out from within a heterogeneous, often anisotropic medium, with only limited visibility of what lies around. A good understanding of the geology and rock mass characterisation, including fabric and structural discontinuities, is critical.  For rock engineers, the ability to tap into connected geotechnical workflows becomes invaluable. The information that you need is likely scattered across multiple systems: geological models, drillhole and core logs, face mapping, laboratory test results, etc. Seequent’s suite of solutions provides a connected data environment where geologists and engineers can collaborate to gain an understanding of the underground conditions. This ‘big picture’ will then be the main input for all the analyses carried out in the area.   Figure 1. Cross-section of an underground mine exported for analysis With PLAXIS, you can accurately simulate the mechanical behaviour of complex rock masses, ranging from massive, blocky to disintegrated or weathered rock. The effect of fabric discontinuities can be captured through equivalent continuum models such as Hoek-Brown with Geological Strength Index (GSI) for isotropic

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PLAXIS 3D – Traditional Tunnelling Method: Application of MTM

This blog is a part of the series Tunnel your way to success with PLAXIS. Introduction  This is the second blog covering the modelling of the Traditional Method of Madrid in PLAXIS 2D and 3D. For further details on the method, please refer to the webinar (Traditional Tunnelling Method: Application of MTM with PLAXIS 2D/3D) and blog 1 (PLAXIS 2D – Traditional Tunnelling Method: Application of MTM). In this paper a 3D Approach to Madrid Traditional Method will be presented. However, a 3D model is not always possible due to project constraints, such as budget and deadlines. This paper aims, firstly, to enhance the current design approaches, via a new 2D approach based on a calibration with a 3D SSI model; secondly, to contribute for a more informed design when a 3D model is not available; and thirdly, to contribute to more sustainable designs without compromising safety and quality. SOIL-STRUCTURE INTERACTION Models   Firstly, it is necessary to create two models: a three-dimensional and a two-dimensional SSI model, based on the first one. To generate both models, the finite element calculation programme PLAXIS 3D and 2D were used, respectively. The geology for both models is covered in Blog 1 and

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PLAXIS 2D – Traditional Tunnelling Method: Application of MTM

This blog is a part of the series Tunnel your way to success with PLAXIS. Introduction  The Traditional Method of Madrid is a method for tunnel construction that has been used for tunnelling in the Madrid Metro network since 1917 (Melis Maynar, M. 2012). The method uses a distinctive excavation sequence that comprises the division of the crown in a series of small excavations that are successively supported by a combination of timber struts, steel waler beams and timber planks during the excavation stage and directly followed by the permanent lining installation. The permanent lining is unreinforced casted concrete (typically C30/37); thus, no reinforcement is normally used. The construction of the walls and invert of the tunnel follow several metres behind, also in the same fashion as an unreinforced concrete permanent liner.  The multiple phases and diverse struct distribution of stresses around the tunnel excavation.  This article presents the methodology followed for the calibration of bidimensional models of tunnels undertaken by the TMM, via three-dimensional models. Furthermore, it discusses the assumptions and calculation strategies used to achieve an appropriate adjustment that permits the validation of 2D models, which can be used for early stages of a similar project.  The Traditional Method

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2D Analysis of a Tunnel Excavation in Rock

Modeling Shotcrete and Cable Bolts: Comparison of FLAC2D and PLAXIS 2D The 2D excavation analysis of a tunnel in a rock mass is explored in this article and some elements of comparison with an identical analysis run in FLAC2D geotechnical analysis software will be discussed. Besides a results comparison, this article will particularly focus on model construction in PLAXIS 2D geotechnical analysis software. (a) Cross Section (b) Profile Figure 1: Tunnel drawings Problem Description The tunnel cross section and profile are provided in Figure 1. The studied tunnel section is constructed at a depth of 654 m in a uniform rock mass with unit weight γrock = 26.7 kN.m-3. The initial stress ratio is respectively equal to K0,x = 0.6 (in-plane horizontal) and K0,z = 0.8 (out-of-plane horizontal). The tunnel is placed at an elevation of 76 m. In order to not have to physically model the entire overburden (and that would have required for the model to extend up to an elevation of 730 m vertically), a fictitious 10 m top layer with unit was introduced at an elevation of 160 m with a unit weight of γoverb = 1522 kN.m-3 equivalent to a 570 m thick overburden with

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PLAXIS Success Story: Road Slope Rupture Remediation

Introduction  Jody Robinson, at DRS-Engineering, works with slope stabilization and retaining walls design, among other geo-structures in California. Waterfront repairs, remediation of wave action on pile walls and tied-back dimensioning are also in the scope of services provided.

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