In-Situ Dynamic Testing of Ground Support Using Simulated Rockbursts

Shotcrete or sprayed concrete is a special concrete designed for spraying onto a surface, as a construction material. With shotcrete application as a ground support system ever-present in both mining and tunnelling sectors, a major requirement of drive progression is to determine when it is safe to reenter beneath freshly sprayed concrete. Accurately determining this time is of paramount importance. Generally, this reentry time is based on measuring the developing strength of shotcrete until an adequate strength value is reached. The issue with current practice is that there is no widely accepted or generally preferred method that accurately assesses the shotcrete lining’s true early-age strength. However, there are a number of strength tests that are commercially available and used in the industry; these include the soil penetrometer, needle penetrometer, bolt screws, beam end testers, and drilled core samples. This paper researches into these testing methods and their characteristics in order to determine their accuracy, testing ranges, and suitability for in situ use in the tunnelling and mining industry. The investigation ultimately reveals that current methods all have substantial shortcomings. Based on these findings, recommendations are proposed for the applicable use of the current testing methods and recommendations for future improvements.

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Impulse Testing of Brickwork Sewers

Journal of Low Frequency Noise Vibration and Active Control ◽

10.1177/026309239501400104 ◽

1995 ◽

Vol 14 (1) ◽

pp. 43-54 ◽

Cited By ~ 2

Author(s):

A. Sibbald ◽

C. A. Fairfield Beng ◽

M. C. Forde Beng

Keyword(s):

Dynamic Testing ◽

Frequency Domain Analysis ◽

Full Scale ◽

Test Method ◽

Scale Model ◽

Integrity Assessment ◽

Analysis Techniques ◽

Non Destructive ◽

Investigation Procedure

This paper describes a study into the application of dynamic testing to the assessment of egg shaped brickwork sewer rings. An investigation procedure using impulsive force hammer excitation with various time and frequency domain analysis techniques is proposed for the location of structural discontinuities in such sewers. The experimental results from a full scale model sewer, and a full scale, in-situ field test on a similar sewer are presented. The chosen non-destructive test method proved to be a convenient tool for the integrity assessment of brickwork sewers.

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Dynamic Mechanical Losses in Filled Poly(Dimethylsiloxane) Networks

Rubber Chemistry and Technology ◽

10.5254/1.3538761 ◽

1995 ◽

Vol 68 (4) ◽

pp. 601-608 ◽

Cited By ~ 10

Author(s):

M. A. Sharaf ◽

A. Kloczkowski ◽

J. E. Mark

Keyword(s):

Mechanical Properties ◽

Glass Transition ◽

Viscoelastic Properties ◽

Network Formation ◽

Dynamic Testing ◽

Glass Transition Temperatures ◽

Dynamic Mechanical ◽

Novel Method ◽

Particulate Silica

Abstract This investigation focused on the study of dynamic mechanical losses in silica-filled networks of poly(dimethylsiloxane) (PDMS). Some of the samples were filled using a novel method, specifically the in situ precipitation of particulate silica either after or during network formation. Others were filled using the customary method of mechanically blending already-prepared silica into the elastomer prior to its crosslinking, and some were prepared without any filler at all. The resulting materials exhibited a variety of relaxation behaviors over the temperature range 120–260 K. The glass transition temperatures Tg showed only a slight dependence on the presence of the filler particles and crosslinks, but the filler was found to reduce both the degree and rate of crystallization for the in situ filled networks. The results obtained document how the techniques employed for incorporating particulate fillers change the viscoelastic properties of an elastomeric network, and how dynamic testing can yield a great deal of insight and useful information on the mechanical properties of polymers in general.

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Dynamic Testing of Open Ground Story Structure and In Situ Evaluation of Displacement Demand Magnifier

Journal of Performance of Constructed Facilities ◽

10.1061/(asce)cf.1943-5509.0001052 ◽

2017 ◽

Vol 31 (5) ◽

pp. 04017055 ◽

Cited By ~ 1

Author(s):

T. Jothi Saravanan ◽

G. V. Rama Rao ◽

J. Prakashvel ◽

N. Gopalakrishnan ◽

N. Lakshmanan ◽

...

Keyword(s):

Dynamic Testing ◽

Story Structure ◽

Open Ground ◽

Displacement Demand

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Fast 4D On-the-Fly Tomography for Observation of Advanced Pore Morphology (APM) Foam Elements Subjected to Compressive Loading

Materials ◽

10.3390/ma14237256 ◽

2021 ◽

Vol 14 (23) ◽

pp. 7256

Author(s):

Michal Vopalensky ◽

Petr Koudelka ◽

Jan Sleichrt ◽

Ivana Kumpova ◽

Matej Borovinsek ◽

...

Keyword(s):

Dynamic Testing ◽

Mechanical Test ◽

Compressive Loading ◽

Time Lapse ◽

3D Models ◽

Pore Morphology ◽

X Ray ◽

Maximum Parameters ◽

3D Information

Observation of dynamic testing by means of X-ray computed tomography (CT) and in-situ loading devices has proven its importance in material analysis already, yielding detailed 3D information on the internal structure of the object of interest and its changes during the experiment. However, the acquisition of the tomographic projections is, in general, a time-consuming task. The standard method for such experiments is the time-lapse CT, where the loading is suspended for the CT scan. On the other hand, modern X-ray tubes and detectors allow for shorter exposure times with an acceptable image quality. Consequently, the experiment can be designed in a way so that the mechanical test is running continuously, as well as the rotational platform, and the radiographic projections are taken one after another in a fast, free-running mode. Performing this so-called on-the-fly CT, the time for the experiment can be reduced substantially, compared to the time-lapse CT. In this paper, the advanced pore morphology (APM) foam elements were used as the test objects for in-situ X-ray microtomography experiments, during which series of CT scans were acquired, each with the duration of 12 s. The contrast-to-noise ratio and the full-width-half-maximum parameters are used for the quality assessment of the resultant 3D models. A comparison to the 3D models obtained by time-lapse CT is provided.

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Research on the Technology of Testing and Evaluation of the Existing Building Foundations

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.121-126.1382 ◽

2011 ◽

Vol 121-126 ◽

pp. 1382-1386

Author(s):

Zhen Shuan Zhang ◽

Yu Deng ◽

Shi Feng Fu

Keyword(s):

Shear Wave Velocity ◽

Static Loading ◽

Dynamic Testing ◽

Loading Test ◽

Existing Building ◽

Test Technology ◽

Testing Technology ◽

Static Loading Test ◽

Testing And Evaluation

In this paper, some technologys are measured and studied with good applicability and reliability,such as static loading test technology,in situ sampling technology,shear wave velocity test technology,GPR testing technology,low strain dynamic testing and settlement observation technology. It can be popularized in engineering.

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