Zonal Disintegration Mechanism of Deep Rock Masses under Coupled High Axial Geostress and Blasting Load

Yuan, Pu; Xu, Ying

doi:10.1155/2018/4957917

Cited by 9 publications

(8 citation statements)

References 25 publications

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“…When first ring fracture occurs around excavated tunnel, it is equivalent to a bigger excavated tunnel in deep rock mass [17]. Due to blasting damage in deep rock mass around excavated tunnel, ring fractures are much easier to happen and fractures near the excavated tunnel are more severe under high axial geostress condition [28]. The final shape and size of excavated tunnel can be obtained by measuring the cut rectangular cemented sand model.…”

Section: Fracture Forms Around Excavated Tunnelmentioning

confidence: 99%

“…Due to the blasting excavation, blasting load effect not only applies a transient load on cemented sand model, but also induces many damages and cracks in cemented sand model and deteriorates its mechanical properties [20]. Moreover, blasting load plays a significant role on the first fracture zone for its rapid attenuation, and it will expand the radius and width of first fractur zone [28]. Therefore, radius scale factor, 1.28, is a little smaller than 1.4 in the research of Chen et al [29].…”

Section: Fracture Forms Around Excavated Tunnelmentioning

confidence: 99%

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Analyses on deformation and fracture evolution of zonal disintegration during axial overloading in 3D geomechanical model tests

Yuan¹,

Xu²

2019

J. vibroeng.

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To investigate the formation of zonal disintegration phenomenon in deep rock mass under high axial geostress, 3D geomechanical model tests for two rock strengths are carried out via capacity of deep rock breakage mechanics and supporting technique model test. Considering the maximum principal stress along the tunnel axis, 3D geomechanical model tests are carried out in a loading procedure of first loading to initial geostress, then excavating the tunnel with blasting construction, and finally overloading the stress along the tunnel. Due to unloading effect, radial strain is tensile and tangential strain is compressive around excavated tunnel after excavation complete, which indicates a radial tension and circumferential compression stress state. With continuous overloading of axial stress, values of both radial tensile strain and tangential compressive strain increase, then ring fracture appears due to large radial tensile strain. After axial overloading, an interval distribution of peaks and troughs is shown in radial tensile strain distribution around excavated tunnel, which indicates a formation of zonal disintegration. By cutting the rectangular cemented sand model, a distinct zonal disintegration phenomenon emerges, and an apparent shrinkage of excavated tunnel is also shown due to radial deformation towards excavated tunnel. The larger the rock strength is, the less the tunnel shrinkage is, the smaller the radius of fracture zone. After statistical analyses of three ring tensile fracture zones, the radius scale factor of fracture zone in zonal disintegration is about 1.28.

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Section: Fracture Forms Around Excavated Tunnelmentioning

confidence: 99%

Section: Fracture Forms Around Excavated Tunnelmentioning

confidence: 99%

Analyses on deformation and fracture evolution of zonal disintegration during axial overloading in 3D geomechanical model tests

Yuan¹,

Xu²

2019

J. vibroeng.

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“…Han et al [20] found that flaw inclination angle and ligament angle remarkably affected dynamic compressive strength and dynamic deformation properties, respectively. Liu et al [21] comparatively analyzed energy consumption properties of vertical bedded and parallel bedded coal-rock and observed that more energy would be needed by vertical bedded coal-rock for the same fractal dimension. Yuan et al [22] investigated the effect of joint angle on zonal disintegration under coupled high in situ axial stress and blasting load and found that the number of cracks after blasting and released strain energy had similar variable tendency.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Behavior and Energy Evolution Characteristic of Deep Roadway Sandstone Containing Weakly Filled Joint at Various Angles

Yuan

2020

Advances in Civil Engineering

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Dynamic impact tests were carried out by implying split-Hopkinson pressure bar (SHPB) apparatus under three-dimensional stress state to investigate the influences of weakly filled joint at seven kinds of angles on dynamic behavior and energy evolution characteristic of deep roadway sandstone (985 m below the surface). The results indicated that rebound strain phenomenon was obvious and the growth rate of stress was in two kinds of phased variations. Dynamic peak strain was inversely proportional to joint angle under three different strain rates. Dynamic compressive strength, elastic deformation modulus, and plastic deformation modulus were in similar variable tendencies with incremental joint angles, showing firstly decrease to minimum value at joint angle of 45° and then increase to maximum value at joint angle of 90°. Moreover, the sensitivity of plastic deformation modulus to joint angle was obviously inferior to that of elastic deformation modulus when joint angle increased from 0° to 45°. Furthermore, both elastic deformation modulus and plastic deformation modulus were independent of strain rate, which was contrary to dynamic compressive strength and dynamic peak strain. Additionally, absorption energy release rate was introduced and defined to describe energy release and conversion characteristics of joint specimens. The changed trend of energy reflection coefficient was completely opposite to that of energy transmission coefficient and absorbed energy release rate. Absorbed energy density was linearly decreased with incremental joint angle and was increased with the increase of strain rate.

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“…However, some scholars believed that rock mass around the excavation was subjected to dynamic loading during the excavation process. Annular zonal fractures were obtained by using the General Particle Dynamics (GPD) method [20,21].…”

Section: Introductionmentioning

confidence: 99%

Numerical Study on Zonal Disintegration of Deep Rock Mass Using Three‐Dimensional Bonded Block Model

Tang

Xie

et al. 2019

Advances in Civil Engineering

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Zonal disintegration, a phenomenon of fractured zones and intact zones distributed alternately in deep rock mass, is different from the excavation-damaged zone of shallow rock mass. In this study, bonded block model of 3DEC was employed to study the fracture mode and origination condition of zonal disintegration. Initiation, propagation, and coalescence progress of fracture around the roadway boundary under different triaxial stress conditions are elaborated. Numerical simulation demonstrated that zonal disintegration may occur when the direction of maximum principal stress is parallel to the roadway axis. It is interesting to find that the fracture around the roadway boundary traced the line of a spiral line, while slip-line fractures distributed apart from the roadway boundary. The extent of the alternate fracture zone decreased as the confining pressure increased, and alternate fracture zone was no longer in existence when the confining pressure reaches a certain value. Effects of roadway shape on zonal disintegration were also studied, and the results indicated that the curvature of the fracture track line tends to be equal to the roadway boundary in shallow surrounding rock of the roadway, while the fractures in deep surrounding rock seems unaffected by the roadway shape. Those findings are of great significance to support design of deep underground openings.

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Zonal Disintegration Mechanism of Deep Rock Masses under Coupled High Axial Geostress and Blasting Load

Cited by 9 publications

References 25 publications

Analyses on deformation and fracture evolution of zonal disintegration during axial overloading in 3D geomechanical model tests

Analyses on deformation and fracture evolution of zonal disintegration during axial overloading in 3D geomechanical model tests

Dynamic Behavior and Energy Evolution Characteristic of Deep Roadway Sandstone Containing Weakly Filled Joint at Various Angles

Numerical Study on Zonal Disintegration of Deep Rock Mass Using Three‐Dimensional Bonded Block Model

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