Hybrid Failure of Cemented Paste Backfill

The hybrid failure is a coupled failure mechanism under the action of tensile and shear stresses. The failure is critical in cemented paste backfill (CPB) since there are no visible signs prior to the failure. Few studies have been conducted on the coupled stress response of CPB. This is most likely due to a lack of suitable laboratory equipment and test procedures. This paper presents a new punching shear apparatus to evaluate the hybrid failure of CPB. We harness two-dimensional finite element analysis (FEA) for supplementing experimental study in providing stress transformation, deformation, and possible failure mechanisms. Our study suggests that the coupled stress is a combination of tensile and shear strength in function of the angle of the frustum. The strengths measured by the coupled stress are comparable to those measured by direct shear and tensile strength tests, in which the strength properties of CPB are curing time and binder content dependent. The FEA results substantiate the effectiveness of proposed model for predicting the hybrid failure of CPB.

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Short Note: Finite-Element Stress Analysis of Avalanche Snowpacks

Journal of Glaciology ◽

10.1017/s0022143000022103 ◽

1971 ◽

Vol 10 (60) ◽

pp. 401-405 ◽

Cited By ~ 7

Author(s):

F. W. Smith ◽

R. A. Sommerfeld ◽

R. O. Bailey

Keyword(s):

Finite Element ◽

Short Note ◽

Single Layer ◽

Shear Stresses ◽

Snow Layer ◽

Element Analysis ◽

Elastic Stresses ◽

State Of Stress ◽

Analysis Calculation ◽

Dimensional Finite Element

Abstract The elastic stresses have been determined, in a single-layer homogeneous snowpack on a realistic avalanche slope, by a two-dimensional finite-element analysis. Calculation of the state of stress throughout the 0.96 m snow layer on a slope approximately that of the Lift Gully at Berthoud Pass, Colorado, resulted in reasonable stress values. In particular, both field experience and the calculated shear stresses predict avalanching in the lower-density snows. Also, tensile stresses were present only in the area of the observed fracture line.

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Case Study of the Effect of Generator Retaining Ring Shrink Fit on Rotor Tooth Top Cracking

ASME 2011 Power Conference, Volume 1 ◽

10.1115/power2011-55302 ◽

2011 ◽

Author(s):

Daniel T. Peters ◽

Kevin M. Haley

Keyword(s):

Three Dimensional ◽

Cyclic Fatigue ◽

Shear Stresses ◽

Element Analysis ◽

Dimensional Finite Element ◽

Retaining Ring ◽

Rotor Tooth ◽

Three Dimensional Finite Element ◽

Shrink Fit

A significant concern in generator operation is cracking in the tops of the rotor teeth due to cyclic fatigue. The shrink fit of a retaining ring over the rotor end induces compressive stresses in the rotor to contain the entire assembly and reduce shear stresses in the rotor teeth during operation. This paper is a case study of the effect of this shrink fit on fatigue life using three dimensional finite element analysis with nonlinear contact to simulate the interaction between the rotor, wedges and retaining ring. For the analysis, consideration was made for both operational and shut down loading to determine the stress state in both conditions for application in fatigue analysis. Overspeed conditions were not considered for this analysis.

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Fiber-Reinforced Cemented Paste Backfill: The Effect of Fiber on Strength Properties and Estimation of Strength Using Nonlinear Models

Materials ◽

10.3390/ma13030718 ◽

2020 ◽

Vol 13 (3) ◽

pp. 718 ◽

Cited By ~ 7

Author(s):

Xin Chen ◽

Xiuzhi Shi ◽

Shu Zhang ◽

Hui Chen ◽

Jian Zhou ◽

...

Keyword(s):

Failure Modes ◽

Nonlinear Models ◽

Fiber Reinforcement ◽

Strength Properties ◽

Sem Analysis ◽

Cemented Paste Backfill ◽

Fiber Reinforced ◽

Shear Cracks ◽

Pull Out ◽

Paste Backfill

This experimental investigation was conducted to research the properties of polypropylene (PP) fiber-reinforced cemented paste backfill (CPB). The unconfined compressive strength (UCS) of the fiber-reinforced CPB showed a significant improvement with average UCS increase ratios of 141.07%, 57.62% and 63.17% at 3, 7 and 28 days, respectively. The macroscopic failure mode and SEM analysis indicated that fibers prevented the formation of large tensile and shear cracks during the pull-out and pull-off failure modes. A linear fitting function for the UCS at a curing time of 3 days and two polynomial fitting functions for the UCS at curing times of 7 and 28 days were established to characterize the relationship between the UCS of the fiber-reinforced and unreinforced CPB. Moreover, based on composite mechanics, nonlinear models related to the UCS and fiber reinforcement index were obtained. The estimated functions containing the fiber reinforcement index λ, which consists of the fiber content and aspect ratio of fiber, could evaluate the UCS. Furthermore, the fiber reinforcement index λ quantifies the enhancement by the fibers. Both estimation results indicated that the UCS values were estimated accurately at curing times of 3, 7 and 28 days in this study. Additionally, the estimation models could be used to guide the strength design of fiber-reinforced CPB. Besides this, the results showed that fiber-reinforced CPB can be used more widely in mine backfills and meets the requirements of controlled low-strength material (CLSM) for broader applications.

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Development of an Ensemble Intelligent Model for Assessing the Strength of Cemented Paste Backfill

Advances in Civil Engineering ◽

10.1155/2020/1643529 ◽

2020 ◽

Vol 2020 ◽

pp. 1-6 ◽

Cited By ~ 2

Author(s):

Yuantian Sun ◽

Guichen Li ◽

Junfei Zhang ◽

Junbo Sun ◽

Jiahui Xu

Keyword(s):

Mine Waste ◽

Construction Materials ◽

Sensitivity Study ◽

Support Vector ◽

Cemented Paste Backfill ◽

Proposed Model ◽

Highly Nonlinear ◽

Paste Backfill ◽

High Prediction ◽

The Stability

Cemented paste backfill (CPB) is an eco-friendly composite containing mine waste or tailings and has been widely used as construction materials in underground stopes. In the field, the uniaxial compressive strength (UCS) of CPB is critical as it is closely related to the stability of stopes. Predicting the UCS of CPB using traditional mathematical models is far from being satisfactory due to the highly nonlinear relationships between the UCS and a large number of influencing variables. To solve this problem, this study uses a support vector machine (SVM) to predict the UCS of CPB. The hyperparameters of the SVM model are tuned using the beetle antennae search (BAS) algorithm; then, the model is called BSVM. The BSVM is then trained on a dataset collected from the experimental results. To explain the importance of each input variable on the UCS of CPB, the variable importance is obtained using a sensitivity study with the BSVM as the objective function. The results show that the proposed BSVM has high prediction accuracy on the test set with a high correlation coefficient (0.97) and low root-mean-square error (0.27 MPa). The proposed model can guide the design of CPB during mining.

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Ultrasonic evaluation of strength properties of cemented paste backfill: Effects of mineral admixture and curing temperature

Ultrasonics ◽

10.1016/j.ultras.2019.105983 ◽

2020 ◽

Vol 100 ◽

pp. 105983 ◽

Cited By ~ 23

Author(s):

Haiqiang Jiang ◽

Hongshun Yi ◽

Erol Yilmaz ◽

Shiwei Liu ◽

Jingping Qiu

Keyword(s):

Strength Properties ◽

Mineral Admixture ◽

Curing Temperature ◽

Cemented Paste Backfill ◽

Ultrasonic Evaluation ◽

Paste Backfill

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INFLUENCE OF TEST CONDITIONS ON STRENGTH PROPERTIES OF THIN-WALL RUBBER PRODUCTS

Bulletin of Belgorod State Technological University named after V G Shukhov ◽

10.34031/2071-7318-2020-5-1-78-84 ◽

2020 ◽

pp. 78-84

Author(s):

D. Kudelin ◽

T. Nesnolovskaya

Keyword(s):

Stress State ◽

Uniaxial Tension ◽

Stress Concentrator ◽

Strength Properties ◽

Complex Stress ◽

Complex Stress State ◽

Complex Stressed State ◽

Shear Stresses ◽

Thin Wall ◽

Element Analysis

A computer simulation of the loading of the rubber membrane by a spherical indenter is performed using a finite element analysis package. It is shown that in the complex stress state rubber based on crystallize rubber IR are significantly inferior in strength properties as in the absence and in the presence of stress concentrator to rubber based on amorphous rubber SBR, while in uniaxial tension they are superior. It is revealed that in the complex stress state, rubbers based on IR rubber filled with 40 parts by weight of carbon black N339 have low resistance to shear stresses, inferior to SBR and BR vulcanizates, which results in low strength properties of rubbers based on it in comparison with strength characteristics determined under uniaxial tension. An analysis of the strength properties of rubbers in the presence of a stress concentrator shows that in a complex stress state, rubbers based on amorphous SBR rubber have the maximum tear resistance, exceeding IR and BR vulcanizates by this indicator, respectively by ~ 4 and 2 times. Under uniaxial tension, the most important factor is the ability of the material to orientation hardening, due to the regularity of the rubber structure and the presence of reinforcing filler, and in the complex-stressed state, the most important factor is a density of the nodes of the fluctuation mesh from the point of view of strength properties.

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THE PROJECTED EFFECT FROM ACCEPTANCE OF CONSTRUCTIVE SOLUTIONS TO ENSURE THE RELIABILITY OF AN INDUSTRIAL FACILITY

Vestnik MGSU ◽

10.22227/1997-0935.2015.11.80-89 ◽

2015 ◽

pp. 80-89

Author(s):

Robert Alekseevich Turusov ◽

Hamed Memarianfard

Keyword(s):

Three Dimensional ◽

Outer Radius ◽

Shear Stresses ◽

Element Analysis ◽

Thermal Residual Stresses ◽

Filament Wound ◽

Inner Radius ◽

Dimensional Finite Element ◽

Interlaminar Shear ◽

Three Dimensional Finite Element

In this paper a three-dimensional finite element analysis employed to predict thermal residual stresses field which arises during the cooling stage at the free edges of a thick walled filament wound cylinder with cross-ply lamination. The inner radius of composite is 50 mm and outer radius is 75 mm and the thickness of steel mandrel is 3 mm. The results showed that the radial stresses near the free ends of the cylinder increased two times compared to radial stresses in the middle of the cylinder and interlaminar shear stresses exceeded 6 MPa close to the free edges.Thus, a two-dimensional stress analysis does not fully reflect the complex state of stress of thick-walled cross-ply filament wound cylinders.

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Analytical Assessment of Internal Stress in Cemented Paste Backfill

Advances in Materials Science and Engineering ◽

10.1155/2020/6666548 ◽

2020 ◽

Vol 2020 ◽

pp. 1-13

Author(s):

Naifei Liu ◽

Liang Cui ◽

Yan Wang

Keyword(s):

Internal Stress ◽

Effective Stress ◽

Water Retention ◽

Operation Time ◽

Model Parameters ◽

Cemented Paste Backfill ◽

Arching Effect ◽

Proposed Model ◽

Paste Backfill ◽

Analytical Assessment

To analytically describe the internal stress in a fill mass made of granular man-made material (cemented paste backfill, CPB), a new 3D effective stress model is developed. The developed model integrates Bishop effective stress principle, water retention relationship, and arching effect. All model parameters are determined from measurable experimental data. The uncertainties of the model parameters are examined by sensitivity analysis. A series of model application is conducted to investigate the effects of field conditions on the internal stress in CPB. The obtained results show that the proposed model is able to capture the influence of operation time, stope geometry, and rock/CPB interface properties on the effective stress in CPB. Hence, the developed model can be used as a useful tool for the optimal design of CPB structure.

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