Overbreak and underbreak in underground openings Part 2: causes and implications

Ibarra, J. A.; Maerz, Norbert H.; Franklin, John A.

doi:10.1007/bf00421947

Cited by 64 publications

(20 citation statements)

References 5 publications

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“…Overbreak is undesirable in every underground space since it increases muckpile volume so as to result in more mucking time (Ibarra et al, 1996a). Excessive contour roughness and overbreak require additional shotcrete volume or rock bolts, increasing support cost (Ibarra et al, 1996b). And also, McKown (1986) has stated that the resulting overbreak and damage to remaining rock can lead to safety problems and additional costs due to additional mucking of extra rock, extra backfill material to fill overbreak and additional rock reinforcement, etc.…”

Section: Introductionmentioning

confidence: 97%

A study on the establishment of Tunnel Contour Quality Index considering construction cost

Kim

Bruland

2015

Tunnelling and Underground Space Technology

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Section: Introductionmentioning

confidence: 97%

A study on the establishment of Tunnel Contour Quality Index considering construction cost

Kim

Bruland

2015

Tunnelling and Underground Space Technology

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“…Therefore, it is urgent to develop a valid and convenient method to predict potential danger in tunnel excavation. Jimin and Mahtab [1] obtained the sizes, shapes, and locations of overbreak blocks by structural plane geometrical characteristics in the case of underground tunnels; Jiamei et al [2] analyzed the effects of surrounding rock and support structure stability by TBM excavation from the angle of quantity; Jian and Xinjiao [3] deduced the statistical regularity of overbreak block sizes and locations in expressway tunnels; Deyun [4] proposed a calculation method of the areas of overbreak and underbreak blocks from the view of mathematics; Huibing [5] applied the drill hole blasting method to seek overbreak and underbreak block sizes and locations; Mingnian and Baoshu [6] used the self-adaption finite element method to analyze the effects of tunnel overbreak blocks on stability of surrounding rock; Revey [7] proposed a control overbreak method of mine tunnel by means of control blasting; Ibarra et al [8][9][10] proposed a light-section method to evaluate the volumes of overbreak blocks and developed the relevant equipment and calculation program; Thidemann [11], Abel [12], and Martna [13] applied numerical method to analyze the interaction of tunnel overbreak blocks and surrounding rock deformation. In fact, overbreak blocks in tunnel excavation arise from two aspects: incorrect excavation and natural structural plane.…”

Section: Introductionmentioning

confidence: 99%

Predictions of Overbreak Blocks in Tunnels Based on the Wavelet Neural Network Method and the Geological Statistics Theory

Sun

Liu

Wei

2013

Mathematical Problems in Engineering

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Predicting overbreak blocks is a valid way to protect constructors, safeties in the process of tunnel excavation. In this paper, a prediction method of the overbreak blocks in tunnels is developed in the frame of the wavelet neural network of geological statistics models. Geometrical parameters of structural plane are first obtained by field survey. Then, a statistical model can be deduced from the measured geometrical parameters on the basis of the geological statistics theory. Furthermore, the volumes and distribution of the overbreak blocks are calculated by the theory of wavelet neural network. Finally, the valid support measurements can be designed according to the prediction results for all overbreak blocks appeared in tunnel excavation, and the amount of overbreak blocks can also be predicted. The code with respect to the method has been developed by the fortran language. The method proposed in this paper has been used in a tunnel construction. The results show that there exists an approximate 10%~30% difference between the prediction and the real volume of overbreak blocks. Therefore, the method can be well used to predict the volumes distribution and the overbreak blocks, and the accordingly support measurements can be also given according to the prediction results.

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“…Soc. Malaysia, Bulletin 46 3) can be grouped into two categories (Ibarra et al, 1996); i.e. 1) the geological factors or the make up character of the ground and 2) the nature of the excavation (blasting) operation.…”

Section: Discontinuities In Blasting Excavations Introductory Remarksmentioning

confidence: 99%

“…The relationship between blasting, geological conditions and overbreak and underbreak has been long discussed (e.g. Hoek and Bray, 1981;Ibarra et al, 1996 and many others), but there has been no systematic and quantitative investigation of them. The geological factors influencing overbreak and underbreak are mainly structural discontinuity planes.…”

Section: Discontinuities In Blasting Excavations Introductory Remarksmentioning

confidence: 99%

“…A study by Ibarra et al (1996) shows that as the rock quality (measured by Q-system of Barton et aI., 1974) improves, the amount of overbreak tends to decrease while that of underbreak tends to increase. They also showed evidence that rock quality may be slightly more influential in causing overbreak, and that explosive energy might be slightly more influential in causing underbreak.…”

Section: Discontinuities In Blasting Excavations Introductory Remarksmentioning

confidence: 99%

See 1 more Smart Citation

Influence of discontinuity on overbreaks and underbreaks in rock excavation - case study from Beris Dam, Kedah, Malaysia

Jamaluddin¹,

Yusoff²

2003

BGSM

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Rock blasting excavation is largely controlled by discontinuities and the strength of the rock materials. although blasting factors are also equally important. This paper presents a case study from the Beris Dam project in Kedah, where a geologist was called upon to clarify a dispute between the contractor and engineers that excessive overbreaks at the Spillway and along the toe slab ofthe Main Dam were largely attributed to geological factors. To verify this issue, detailed mapping on the geological structures was carried out on the resulting exposures. Focus of the mapping was mainly on observing the nature of the rock failures (overbreaks) and collection of discontinuity data (joints, bedding, shear zones, fault). The discontinuity data were analysed kinematically by using stereographic projection to verify the mode of rock breakage. Results of the analyses indicated and conformed with the field evidences, that the overbreaks were clearly controlled by the unfavourable intersections of the bedding planes, joints, faults and shear zones with respect to the blasting lines. Overbreaks in the Spillway and the Main Dam usually occurred in wedge and planar mode of failures.Abstrak: Kerja-kerja penggalian batuan sangat dipengaruhi oleh ketakselanjaran dan kekuatan bahan batuan, walaupun diakui bahawa dan faktor-faktor peletupan juga berperanan penting. Kertas kerja ini cuba menyajikan suatu contoh kajian kes daripada projek Empangan Sg. Beris, Kedah. Di dalam projek ini geologis profesional telah diundang untuk mengesahkan bahawa kejadian terlebih korek yang berlaku di tapak alur limpah dan kaki empangan utama disebabkan oleh faktor-faktor geologi. Untuk mengesahkan punca kepada masalah ini, pemetaan terperinci telah dijalankan di tapak" tapak berkenaan. Pemetaan geologi tersebut tertumpu kepada pencerapan keadaan kegagalan bantuan dan pengumpulan data-data ketakselanjaran (kekar, perlapisan, sesar dan zon ricih). Data-data orientasi ketakselanjaran telah dianalisis secara kinematik dengan menggunakan unjuran stereografi untuk melihat potensi ragam kegagalannya. Hasil analisis jelas menunjukkan bahawa kejadian terlebih korek memang dikawal oleh ketakselanjaran kerana orientasi garis letupan batuan yang dipilih mendedahkan potongan cerun batuan kepada kegagalan baji dan satah.

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Overbreak and underbreak in underground openings Part 2: causes and implications

Cited by 64 publications

References 5 publications

A study on the establishment of Tunnel Contour Quality Index considering construction cost

A study on the establishment of Tunnel Contour Quality Index considering construction cost

Predictions of Overbreak Blocks in Tunnels Based on the Wavelet Neural Network Method and the Geological Statistics Theory

Influence of discontinuity on overbreaks and underbreaks in rock excavation - case study from Beris Dam, Kedah, Malaysia

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