Probability distributions of shotcrete parameters for reliability-based analyses of rock tunnel support

Bjureland, William; Johansson, Fredrik; Sjölander, Andreas; Spross, Johan; Larsson, Stefan

doi:10.1016/j.tust.2019.02.002

Cited by 26 publications

(17 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For both tests, at least 80 % of the fracture zone was located at the interface. Based on data from 354 tests done during the construction of a tunnel in the same region, Bjureland et al [25] presented a mean value and standard deviation for bond strength between shotcrete and rock of 0.81 MPa and 0.31 MPa, respectively. This indicates that sufficient bond strength in some cases can be achieved without curing.…”

Section: Bond Strength Testingmentioning

confidence: 99%

In-Situ and Laboratory Investigation on Leaching and Effects of Early Curing of Shotcrete

Sjölander

Ansell

2019

Nordic Concrete Research

Self Cite

View full text Add to dashboard Cite

During the construction of a rock tunnel in Stockholm, several sections with leaching shotcrete (sprayed concrete) were found one year after the spraying was completed. An investigation was therefore conducted, and its results are presented in this paper. The amount of leaching after such a short time indicated that a one-sided water pressure existed in combination with a permeable shotcrete. The reason for the water pressure was likely a partly unsuccessful grouting that created sections with leaking water. The permeable shotcrete could be a combined result of insufficient curing and the use of accelerators, and the effect of in-situ curing was therefore investigated. A total of six slabs were sprayed and cured under different conditions in the tunnel. Test results according to standards indicated that curing has no significant effect on the development of mechanical strength or water penetration through the shotcrete. However, this is believed to be a result of the test method rather than the non-existing effect of curing. Lastly, some modifications to the test standard were proposed for future studies of in-situ curing.

show abstract

Section: Bond Strength Testingmentioning

confidence: 99%

In-Situ and Laboratory Investigation on Leaching and Effects of Early Curing of Shotcrete

Sjölander

Ansell

2019

Nordic Concrete Research

Self Cite

View full text Add to dashboard Cite

show abstract

“…The analysis of precipitation data is extremely important for strategic planning and decision-making in various natural and socio-economic systems, such as agricultural planning (Stern & Coe 1982;Hussain et al 2010), civil engineering (Bjureland et al 2019), hydrology (Bedient et al 2008;Langat et al 2019;Brendel et al 2020), water resources management ( Jain & Singh 1979), among others. The search for the probability distribution that best fits the precipitation data, for the highlighted systems, was the objective of several studies (Önöz & Bayazit 1995;Olofintoye et al 2009;Alam et al 2018) because by using the identified distribution, it is possible to predict future events, such as the probability of rain occurring in a given region (Sȩn & Eljadid 1999).…”

Section: Introductionmentioning

confidence: 99%

Best-fit probability distribution models for monthly rainfall of Northeastern Brazil

Ximenes

Silva

Ashkar

et al. 2021

Water Science and Technology

View full text Add to dashboard Cite

The analysis of precipitation data is extremely important for strategic planning and decision-making in various natural systems, as well as in planning and preparing for a drought period. The drought is responsible for several impacts on the economy of Northeast Brazil (NEB), mainly in the agricultural and livestock sectors. This study analyzed the fit of 2-parameter distributions gamma (GAM), log-normal (LNORM), Weibull (WEI), generalized Pareto (GP), Gumbel (GUM) and normal (NORM) to monthly precipitation data from 293 rainfall stations across NEB, in the period 1988–2017. The maximum likelihood (ML) method was used to estimate the parameters to fit the models and the selection of the model was based on a modification of the Shapiro-Wilk statistic. The results showed the chosen 2-parameter distributions to be flexible enough to describe the studied monthly precipitation data. The GAM and WEI models showed the overall best fits, but the LNORM and GP models gave the best fits in certain months of the year and regions that differed from the others in terms of their average precipitation.

show abstract

“…Consequently, extensive research works were accomplished in connection with designing rock support in excavations. As a result, several innovative supporting devices and methods of design of rock supports and have been proposed over the past few years and include numerical modeling (Boon et al 2015;Hu et al 2019;Nie et al 2018), empirical charts (Barton et al 1974;Chan and Einstein 1981;Rehman et al 2019), analytical methods including the key block theory (Fu and Ma 2014;Zhang et al 2020;Zou and Zhang 2019); probabilistic methods (Lü et al 2012;Oreste 2005); expert systems (Madhu et al 1995); lab and in-situ testing and monitoring (Bjureland et al 2019;Li 2006;Napa-García et al 2017;Wu et al 2019;Yokota et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Reliability Analysis of Rock Supports in Underground Mine Drifts: A Case Study

2021

View full text Add to dashboard Cite

Support failures in mine drifts represent potential hazards threatening underground mine safety and productivity. The aim of this study is to determine the reliability index associated with the rock supporting elements used in Ridder-Sokolny mine, an underground mine located in East Kazakhstan. Numerical simulations of the drift support and the first order reliability method (FORM) were employed to carry out the analysis. Several support cases were considered including; shotcrete, bolting, concrete, and combined bolting and concrete as well as unsupported drift case. For each support case, the factors of safety (FS), the reliability index (β) and the probability of failure (PF) were determined in accordance with the corresponding rock mass quality and excavation geometry. The results indicated the average FSs varied little for the different support cases (except for shotcrete); while β and PF vary more significantly between 0.62-3.25 and 0.05-27 (×10 3 %) factor depending on the rock conditions and support installed. The probability of failure of the rock support increases with a decrease in the rock mass quality. Similar trends were observed with an increase of the width/height ratio of the excavations for the same rock domain. These results illustrated that a single FS value obtained from a deterministic method may not always provide a sufficient indication of safety. This is in agreement with the field observations (many of the supports failed). Hence, on the basis of the reliability index of the supports, the requirement in terms of coefficient of variability of the rock mass quality to meet the target performance level was proposed. It is concluded that the results of this study could help improving the drift support design in Ridder-Sokolny mine.

show abstract

Probability distributions of shotcrete parameters for reliability-based analyses of rock tunnel support

Cited by 26 publications

References 41 publications

In-Situ and Laboratory Investigation on Leaching and Effects of Early Curing of Shotcrete

In-Situ and Laboratory Investigation on Leaching and Effects of Early Curing of Shotcrete

Best-fit probability distribution models for monthly rainfall of Northeastern Brazil

Reliability Analysis of Rock Supports in Underground Mine Drifts: A Case Study

Contact Info

Product

Resources

About