Tunnel Design and Underground Structures

El shotcrete convencional, tal como lo conocemos, requiere una planta dosificadora, un equipo de transporte de la mezcla y un lanzador robótico. Este es el sistema de sostenimiento con shotcrete utilizado por la mayoría de las minas subterráneas en todo el mundo en la actualidad. La minería subterránea constantemente incrementa los niveles de profundización del minado lo cual requiere la aplicación de shotcrete de mayores espesores. Los volúmenes de material requeridos también se incrementan, así como la distancias que se tienen que recorrer aumentado los costos y disminuyendo la productividad.

Con estos desafíos que enfrentan las minas, hemos desarrollado un nuevo shotcrete vía húmeda denominado MineCreteS3 (MineCrete S3) Shotcrete Híbrido, el primero en su tipo. Es una mezcla de 3 partes que consta de cemento, agregado y agua. Ya no se necesitan aditivos adicionales como retardadores, aceleradores, plastificantes, antiespumantes, cenizas volcánicas y humo de sílice. MineCrete S3 se entrega en forma de polvo que incluye todos los aditivos requeridos ya mezclados y combinados con la opción de incluir también la fibra de refuerzo.

¿Por qué lo llamamos al MineCrete S3 un "Shotcrete Híbrido"?, Lo denominamos así, porque hemos combinado las ventajas de un TSL (Thin Spray-On Liners, Revestimientos de espesores delgados) y las ventajas del shotcrete vía húmeda. Los TSL utilizan polímeros para incrementar la resistencia a la adherencia, tracción y corte, y que son altamente superiores al shotcrete convencional. El shotcrete convencional utiliza principalmente la resistencia a la compresión y la absorción de energía para desarrollar un sistema de soporte estructural que puede trabajar de forma segura en cualquier tipo de roca, especialmente en condiciones de terrenos de muy mala calidad geotécnica, altas deformaciones y presencia de agua.

Basic Concepts and Recommended Procedures for Numerical Analysis related to Mining and geotechnical By FLAC3D
Instructor: Khezr Mohammadamini
Organizer: Student Scientific Society of Mining Engineering
University of Tehran
Follow Khezr Mohammadamini to Free training.
Language: Persian (فارسی)
___________________________________________________
#FLAC3D #ITASCA #FLAC
#numericalanalysis #training #mining #geotechnical #free
#rock_mechanics #civil #oil #gas #plaxis #university #engineer #engineering #society #research
Itasca Consulting Group, Inc.

Sydney Metro is Australia's biggest public transport project.

Stage 2 of the project will extend metro rail from the city's northwest under Sydney Harbour, through new stations in the CBD and southwest to Bankstown.
Sydney Metro has two core components:
- Sydney Metro Northwest -now under construction and to open in the first half of 2019
- Sydney Metro City and Southwest a new twin 12.5-km tunnel linking with Sydney Metro Northwest at Chatswood
- then under Sydney Harbour, through the CBD to Sydenham and continuing 13. 4 km along the existing line to
Bankstown due for completion in 2024.
A joint venture between Parsons Brinckerhoff and AECOM (PB-AECOM JV) was appointed as the consultant for the Sydney Metro Technical Services project, which commenced in September 2014. The team will prepare a preliminary evaluation, scoping design, definition design and ultimately reference designs for the Sydney Metro Stage 2.
In November 2014 the marine geophysics contract was awarded to Earth Technology Solutions Pty Ltd and the intrusive investigation followed in April 2015 by the Golders-Douglas Partners joint venture.
As Sydney Harbour is a key element of Sydney Metro, early planning and design work included essential geotechnical investigations. Sydney Harbour is a busy waterway, so the investigation works began, after extensive consultation with all relevant harbour authorities, with standard marine geophysical surveys (reflection, 1 refraction, 1 magnetics and sonar) west of the Sydney Harbour Bridge.
Land-based investigation began in April 2015 following extensive community consultation and services searches. The firstnole (BH015) began at Blues Point with a commissioning ceremony by the NSW Premier Mike Baird. This was the start of 27 boreholes that extend from Chatswood to Sydenham. These boreholes have been planned to target and intersect the Ashfield Shale, Mittagong Formation and Hawkesbury Sandstone to assess the rocks geomechanical properties.

Was befndet sich im Untergrund? Der Keller mit der
Waschmaschine, ein Parkhaus, Wasserleitungen, vielleicht irgendwo eine Erdwärmesonde. Und was kommt danach, in fünfundert Metern Tiefe? Welche Gesteine bilden den geologischen Untergrund an der Stelle, wo
wir gerade stehen? Das überlegen wir uns selten, es ist ja nicht sichtbar. Auch die Raumplanung befasst sich in erster Linie mit dem, was von der Oberfäche aus nach oben geht, nicht nach unten. Immer mehr Projekte wollen aber den Untergrund nutzen: die erwähnten Erdwärmesonden, Wohnungen oder andere Bauten, Cargo sous terrain (ein unterirdisches Logistiksystem, das Schweizer Zentren verbinden soll), CO2-Speicher, Endlager für radioaktive Abfälle. Doch selbst für Wissenschaftler*innen ist der Untergrund noch immer zum grossen Teil terra incognita.
Wir haben mit dem Geologen Martin Mazurek über Bohrungen gesprochen und mit der Historikerin Silvia Berger, wie die Menschen den Untergrund wahrnehmen und was bei Projekten refektiert werden sollte.

The new subway line passes under an existing subway line and an under pass roadway. The new tunnel is going to be built with a tunnel boring machine (TBM) using the earth pressure balance (EPB) procedure. In order to define the geotechnical and mechanical effects that the construction of the new line might have on these structures, an instrumentation system was implemented. To prevent any structural misbehavior on the existing under pass and the subway line, it is necessary to have a strict control of the TBM parameters, such as the face-support pressure and the slurry characteristics; hence, data from the machine sensors were stored. Knowledge of these parameters allows for monitoring of settlements during the construction process and that will lead to protection of the surrounding structures and eventually to predict the possible long-time subsidence effects. Outside the structures, tiltmeters and topographic references were installed. Inside the tunnel, deformations were measured through an automated system to prevent any possible damage due to unexpected factors. In this paper, the selection criterion, for the sensors used in the instrumentation system, is described. The monitoring process and the relevant data gathered from the system are presented and explained herein. Conclusions led to important correlations that can be used for future works.

The existing Salang tunnel connects Kabul to Northern Provinces of Afghanistan. The tunnel was built by So-viets engineers in 1960s and it is about 2600 m long. The tunnel is located at an altitude of 3400 m so that the portals and mountains are subjected to severe environmental conditions such as freezing and thawing process. As the traffic is heavy and the present tunnel is narrow, a new tunnel is planned by the Ministry of Public Works of Afghanistan using modern tunnel excavation techniques. The existing geotechnical data and newly gathered geotechnical and environmental data are used for rock engineering assessment of the tunnel. This study describes the rock engineering assessment of the existing Salang tunnel, mainly. The authors discuss the support system of the existing tunnel according to RMQR and other rock classification systems. They also es-timate the response and stability of the existing tunnel through an integrated system of tunnel design incorpo-rating the RMQR rock classification system and discuss its implications on the planned tunnels.

Le béton projeté conventionnel tel que nous le connaissons nécessite d'une centrale à béton, un mélangeur à baril et un pulvérisateur robotisé. C’est le
système de support utilisé pour la majorité des mines souterraines dans le monde aujourd’hui. Une exploitation minière plus profonde nécessite une
application de béton projeté plus épaisse. Les volumes du matériel nécessaires à l’application du béton projeté ainsi que la distance parcourue augmentent leurs coûts et diminuent la productivité.

Face aux défis que les mines confrontent, nous avons développé un nouveau béton projeté humide appelé MineCreteS3 (MCS3) Shotcrete Hybrid, un premier du genre. Il s’agit d’un mélange de trois parties composé de ciment, d’agrégat et d’eau. Les additifs tels que les retardateurs, les accélérateurs, les plastifiants, les démoussant, les cendres volantes et les fumées de silice ne sont plus nécessaires. MCS3 se présente sous forme de poudre avec tous les additifs mélangés et avec l’option de fibres pré mélangées.

Pourquoi appelons-nous Minecrete S3 un "béton projeté (Shotcrete) hybride"? C’est parce que nous avons combiné les avantages d'un TSL et les
avantages du béton projeté humide. Le TSL utilise des polymères pour créer une haute résistance à la traction (tensile), les forces de liaison à la traction (tensile bond) et au cisaillement élevées (shear bond) que le béton projeté (Shotcrete) n’a pas. Le béton projeté conventionnel utilise la force de compression et l'apsorbtion d'énergie pour créer un système de support structurel qui peut fonctionner en toute sécurité dans tout type de roche, surtout, un sol en très mauvaises conditions contenant des haute déformations et de l’eau.

This work aims to better understand improvements in history of the rock bolt support. Although the rock bolt was invented more than one hundred years before, its usage has increased in mining and tunneling industries since the 1930s. Then, the steel rock bolts have become one of the most widely used tunnel supports since the third quarter of the 20th century, which was a time of changing strategies regarding supports and many challenges faced concerning the use of new support materials. Twenty inventions in the rock bolt history from its start of usage to nowadays are briefly explained in this paper. It can be inferred from the listed matters in this paper that many of the important developments in the rock bolt history were because of the need for use of new materials like contemporary grout materials increasing the load bearing capacity or rock bolts made with engineering polymer materials having good resistivity against the ground water. Also, developments in the mechanical science have made rock bolting an effective support method due to improvements such in the drilling technology or new anchoring mechanisms developed to overcome the problems in rock bolting. As a result of growing applications during 20th and 21th centuries, new challenges have come into being as in the energy-absorbing rock bolts being improved for the rock burst problem since 1990s.