Search results for: Latest H19-461_V1.0 Exam Questions Vce π― H19-461_V1.0 Labs π H19-461_V1.0 New Study Plan π Search for β H19-461_V1.0 οΈβοΈ on γ www.pdfvce.com γ immediately to obtain a free download π§H19-461_V1.0 Best Vce
-
In situ Stress Testing for Tunnel Design in Sydney β Hydraulic Fracturing and Overcoring
Over the last decade there have been several road and rail tunnels designed within the Sydney Metropolitan area that are now well into construction. For these tunnelling projects, a key design input has been an estimate of the magnitude and orientation of the in situ stress. Designers typically consider the measurement of in situ stress from boreholes located along the project alignment and also from published stress measurements and empirically derived relationships for the Sydney Basin. This is because there is often significant variability in the results obtained from limited stress measurements for a given project and a reasonable interpretation of these results needs to take into account a number of factors such as geological and topographical situation. Measurement technique is also a source of variation and practitioners need to be aware of the limitations and advantages of these to ensure that a stress measurement program has the opportunity to deliver the required project needs. This paper considers in situ measurements made within boreholes in Sydney using the commonly-used hydraulic fracturing method and the more recently used overcoring method by the Sigra IST tool. Results from two infrastructure projects, where these two methods were used, are presented and the possible reasons for differences obtained between the two methods are discussed. The process of overcoring is a focus including the factors that influence the determination of the elastic properties of the rock for the calculation of the in situ major horizontal stress. Numerical modelling is used to examine the potential for brittle microcracking in the porous Sydney sandstones, which can damage an overcored sample and invalidate elastic parameters obtained.
-
NPER specific area of practice landslide risk management
You will find on the following pages a final draft of the guideline for applicants on eligibility criteria and procedures for recognition in the specific area of practice within the National Professional Engineers Register (NPER) for Landslide Risk Management.
This document is being published here to permit comment by the membership of AGS prior to forwarding the completed document to the National Engineering Register Board (NERB) for their consideration for its implementation.
You would recall that the development of a specific area of practice for LRM within the National Professional Engineers Register (NPER) is in response to requirements of legislation, and is a means for practitioners to demonstrate competency as required by such legislation. At the moment, that means areas covered by NSW Kosciusko Alpine (under NSW SEPP75), Victorian Alpine (under an EMO), and Pittwater Council area in the northern beaches of metropolitan Sydney (under an Interim Geotechnical Policy). Wollongong City Council also is in the process of updating its policy in a comparable fashion. Each of these pieces of legislation is similar in that they all require practitioners to be chartered professionals (i.e. CPEng, CPGeo or RPGeo) and “to demonstrate core competencies in landslide risk management”. The specific area of practice under NPER for LRM will be a means of demonstration of those competencies, where required by these pieces of legislation. At present, there is no means, other than by CV, to provide this demonstration of competency. The National Committee believes that leaves several challenges in regards to such assessment.
A competency panel populated by representatives of our Society, as well as the Civil College of Engineers Australia, has developed the guideline. The competency panel has reported directly to the National Committee of AGS as progress has been made. The philosophy adopted in the development of the specific area of practice of Landslide Risk Management within NPER was approved at the November 2004 National Committee meeting. In addition, the first draft was circulated to the AGS LRM Sub-Committee for comment; this committee has representatives nationwide. The text of the final draft guideline was presented to the AGS National Committee meeting in April 2005, wherein the philosophy of the approach was again endorsed. Since that time, the registration guideline has been subjected to review and a flowchart developed which explains the process. The flowchart is presented in Figure 2. This was reported to you in the previous issue of Australian Geomechanics.
-
Boundary Element Methods for the Simulation of Underground Construction
For the simulation of underground excavation (tunnelling or cavern excavation) the Boundary Element Method offers advantages. For infinite or semi-infinite domains the radiation condition is explicitly fulfilled and the effort in discretization (surface instead of volume discretization) and solving the modelling system is reduced by an order of magnitude. One of the reasons why the method is applied rarely in practice is that essential aspects, such as modelling the sequential excavation, the efficient treatment of nonlinear material behaviour, inhomogeneous ground conditions and support construction were missing. In addition the method requires more computational efforts, run times for large 3D problems can become unacceptably long. The paper will present the research work carried out at the Institute for Structural Analysis at Graz University of Technology (with European and Austrian sponsorship). The research includes the implementation of efficient methods dealing with the above mentioned requirements for a practical application of the method to underground excavation problems.
It will be shown on a 3D example in tunnelling how the method can now efficiently deal with the sequential excavation / construction. Fast solution techniques were implemented to ensure that the results are obtained in a reasonable time for large 3D problems.
-
Reliability of the linear correlation of Rock Mass Rating (RMR) and Tunnelling Quality Index (Q)
With the advent of the RMR and Q classification methods for underground excavation support design, a linear correlation between the two methods was suggested by linear regression analysis of the data obtained from several case studies. The data used in deriving the relationship was widely scattered and the range of values covered by the 90% confidence limits demonstrated that the relationship had very little practical value. In subsequent publications, the 90% confidence limits were omitted when referring to the relationship. Consequently, some practitioners in the field of rock engineering assumed that this relationship, expressed as a semi logarithmic equation, is universally applicable for transforming the ratings assigned by one system to the ratings of the other. This assumption is erroneous and deserves scrutiny. This paper reviews some of the relevant published information and illustrates that there is no sound scientific basis to assume a universally applicable linear relationship between the two.
-
Convict mines of Newcastle
In his interesting and informative paper on the abandoned mine workings under Newcastle Hawkins (2005) refers to the workings mapped under the Newcastle Hospital (Newmed site) and supplies a plan (his Fig, 3) prepared by Moelle, Branagan and MacGregor (n.d.). While this plan is mentioned as coming from Coffey Geosciences (1979), this mapping was also described, albeit briefly. in Branagan and Moelle (1981), in a presentation accompanied by a number of coloured slides taken on the surface and underground. We differ from both Hawkins and Coffey Geosciences in attributing the mining to the Yard Seam and not the Dudley Seam. The area mined occurs between two readily recognisable faults, and it was postulated that there might be a connection with workings located beneath the Police Station and City morgue (Fig. I).
The original mapping has a number of details not shown in Hawkins’ Figure 3 and it seems appropriate that the map be reproduced at a larger scale with the additional information (essentially a working sheet), which might prove useful for future investigations (Fig. 2).
Branagan and Moelle (op. cit) postulated that the workings were possibly from 1814. The plan of March 1816 by Lt. C. Jeffreys (1782 – 1826) identifies this locality as the site of the operating coal mines at that time (Fig 3) (Branagan 1972). This map distinguishes them clearly from the 1804 workings, which are shown on the Newcastle Coal Mine Map available on the Coal River website. These workings were under Signal Hill, as they are shown as occurring 70 feet above sea-level, and the same distance below the top of the hill. That plan shows some systematic development (not quite bord and pillar), but the drives with several bends (H, I, K and L, M, N), possibly for exploration, show some similarities to the pattern of working which was used beneath the Newmed site. These older convict working drives might have been made to cut through coal coked by dyke intrusion or affected by faulting. The somewhat less systematic workings under the hospital possibly suggest a change in the mining foreman. Nevertheless, the work (particularly the arrangements for ventilation) was clearly being carried out by workmen with mining experience. Further research is clearly warranted to clarify the extent of mining under the city centre and to minimise the risk of foundation failure during further development of the area.
-
Two- and three-dimensional undrained bearing capacity of embedded footings
The ability to predict the ultimate bearing capacity of a foundation is one of the most important problems in foundation engineering. To solve this problem, geotechnical engineers routinely use a bearing capacity equation that contains a number of empirical factors to account for foundation shape, depth and inclination. In this paper finite element analysis is used to predict the undrained bearing capacity of strip, square, rectangular and circular footings embedded in clay. From these analyses, rigorous shape and depth factors have been derived and are compared with previous numerical and empirical solutions in the literature. The bearing capacity behaviour is discussed and the bearing capacity factors are given for various cases involving a range of embedment depths and footing shapes.
-
Strengthening Reinforced Earth Walls β Knox Road Duplication Case Study
In 1979, The Reinforced Earth Company (RECO) designed and supplied Reinforced Earth walls (REWs) at Knox Road bridge over main Western rail line at Doonside, NSW. The arrangement comprised a pair of abutments spanning over rail. In 1979, the REWs were constructed with two traffic lanes on the Eastern side (Stage 1), and with provision for a further two traffic lanes to be added on the Western side (Stage 2). Between 1979 and 2011, the Western side of the abutments were left in a relatively unfinished condition in readiness for the Stage 2 abutment to be constructed.
The original design of the REWs was carried out on the assumption that when the Stage 2 duplication was to occur, the same abutment beam seat, relative founding level and bridge loading would apply. However, the Stage 2 duplication design, developed in 2011, required a larger abutment beam seat and significantly higher bridge loads than the original design assumed. This meant that there was insufficient earth reinforcement capacity within the existing REW structure to safely support the new bridge loading.
To increase the existing capacity, additional galvanised metallic soil reinforcing strips (RE strips) were incorporated into the REWs. This increase in capacity was achieved by a combination of installing new reinforcing strip connections to existing panels and fabricating new facing panels. The work involved a staged construction process with the initial stage comprising removal and replacement of under-strength panels and retro-fitting with new reinforcing strip connections. The second stage of construction comprised conventional construction of the REW to the new finished surface level incorporating newly fabricated facing panels. Impact on existing road and rail users was paramount during the design and construction of the bridge. It was important to keep the existing road open as much as possible, and the reduce the amount of works in the Rail Corridor. This Case Study presents an innovative method of strengthening existing structures, while reducing costs and construction impacts on both road and rail users in an urban environment.
-
Brown gold: redevelopment of former quarry and landfill sites
This paper presents a discussion of key geotechnical considerations and challenges associated with the rehabilitation and redevelopment of former quarry and landfill sites, including open quarry pits to be backfilled with imported engineered fill and former quarry pits that are already backfilled with uncontrolled fill materials where it is not practical to remove the landfill/uncontrolled fill materials as part of the rehabilitation/redevelopment. Geotechnical considerations and challenges that are discussed include the importance of communication with regulatory authorities throughout planning, design and handover, the challenges associated with geotechnical investigation of former landfill sites, the availability of materials from onsite sources or importation for use as engineered fill, requirements for assessing and monitoring ground settlement and the importance of quality assurance (e.g. Level 1 inspection and testing) during rehabilitation/redevelopment earthworks. Development outcomes ranging from public open space to residential or commercial development are also discussed.