Analytical Assessment of Internal Stress in Cemented Paste Backfill

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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Influence of Load Path and Effective Stress on One-Dimensional Deformation of Cemented Paste Backfill (CPB) During Deposition and Curing

Geotechnical and Geological Engineering ◽

10.1007/s10706-021-02030-4 ◽

2022 ◽

Author(s):

Mohammad Shahsavari ◽

Mohammadamin Jafari ◽

Murray Grabinsky

Keyword(s):

Effective Stress ◽

Cemented Paste Backfill ◽

Load Path ◽

One Dimensional ◽

Paste Backfill

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Hybrid Failure of Cemented Paste Backfill

Minerals ◽

10.3390/min11101141 ◽

2021 ◽

Vol 11 (10) ◽

pp. 1141

Author(s):

Andrew Pan ◽

Mohammadamin Jafari ◽

Lijie Guo ◽

Murray Grabinsky

Keyword(s):

Strength Properties ◽

Shear Stresses ◽

Cemented Paste Backfill ◽

Test Procedures ◽

Element Analysis ◽

Laboratory Equipment ◽

Proposed Model ◽

Dimensional Finite Element ◽

Paste Backfill ◽

Coupled Stress

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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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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Correlation between the Pore Structure and Water Retention of Cemented Paste Backfill Using Centrifugal and Nuclear Magnetic Resonance Methods

Minerals ◽

10.3390/min10070610 ◽

2020 ◽

Vol 10 (7) ◽

pp. 610

Author(s):

Rugao Gao ◽

Keping Zhou ◽

Wei Liu ◽

Qifan Ren

Keyword(s):

Pore Size Distribution ◽

Pore Size ◽

Size Distribution ◽

Water Retention ◽

Water Retention Capacity ◽

Cemented Paste Backfill ◽

Solid Concentration ◽

Retention Capacity ◽

Cutoff Value ◽

Paste Backfill

This research combines a centrifugal test and nuclear magnetic resonance (NMR) technology to study the water retention capacity of the cemented paste backfill. Backfill samples with cement–tailings ratios of 1:4, 1:8, and 1:12, and solid concentrations of 71%, 74%, 77%, 80%, and 83% respectively, were prepared for the test. The relative centrifugal force ( RCF ) required for accurate testing and the T2 cutoff value that characterizes the water retention capacity were obtained through an NMR test on the backfill samples after centrifugation in saturated conditions. Based on the soil–water characteristic curve (SWCC), the NMR pore water characteristic distribution model was established, and the pore size distribution and effective water retention characteristics were analyzed. This study shows that when the rotating speed is between 1500 and 4000 rpm, the R C F of the backfill ranges from 125.8 to 894.4 g/min , and the T2 cutoff value will vary from 3 to 10 ms. With an increase in solid concentration of the backfill, both the RCF and T2 cutoff value decline. The Scanning Electron Microscope (SEM) analysis confirms that an increase in the solid concentration and cement–tailings ratio will lead to obvious bimodal characteristics of the pore size distribution curve of the backfill. In addition, the porosity will decrease, the critical pore value, which represents a value to distinguish pores with different movable fluid retention capabilities and characterizes the pore size classification, will become smaller, and the pore size distribution will become more diverse. These changes indicate that a high-concentration backfill can effectively reduce the flow of a fine-grained matrix with large pores.

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In-Plane Flexible Ring Tire Model—Part 1: Modeling and Parameter Identification

Tire Science and Technology ◽

10.2346/tire.18.460303 ◽

2018 ◽

Vol 46 (3) ◽

pp. 174-219 ◽

Cited By ~ 2

Author(s):

Bin Li ◽

Xiaobo Yang ◽

James Yang ◽

Yunqing Zhang ◽

Zeyu Ma

Keyword(s):

Static Load ◽

Model Parameters ◽

Tire Model ◽

Test Results ◽

Lumped Mass ◽

Virtual Test ◽

Proposed Model ◽

Particle Swarm Method ◽

Vehicle Dynamic Simulation ◽

Flexible Ring

ABSTRACT The tire model is essential for accurate and efficient vehicle dynamic simulation. In this article, an in-plane flexible ring tire model is proposed, in which the tire is composed of a rigid rim, a number of discretized lumped mass belt points, and numerous massless tread blocks attached on the belt. One set of tire model parameters is identified by approaching the predicted results with ADAMS® FTire virtual test results for one particular cleat test through the particle swarm method using MATLAB®. Based on the identified parameters, the tire model is further validated by comparing the predicted results with FTire for the static load-deflection tests and other cleat tests. Finally, several important aspects regarding the proposed model are discussed.

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EXPONENTIATED HALF-LOGISTIC LOMAX DISTRIBUTION WITH PROPERTIES AND APPLICATION

NED University Journal of Research ◽

10.35453/nedjr-ascn-2018-0033 ◽

2019 ◽

Vol XVI (2) ◽

pp. 1-11

Author(s):

Farrukh Jamal ◽

Hesham Mohammed Reyad ◽

Soha Othman Ahmed ◽

Muhammad Akbar Ali Shah ◽

Emrah Altun

Keyword(s):

Real Data ◽

Continuous Model ◽

Model Parameters ◽

Data Set ◽

Lomax Distribution ◽

Mathematical Properties ◽

Proposed Model ◽

Probability Weighted Moment ◽

Record Statistics ◽

Maximum Likelihood Criterion

A new three-parameter continuous model called the exponentiated half-logistic Lomax distribution is introduced in this paper. Basic mathematical properties for the proposed model were investigated which include raw and incomplete moments, skewness, kurtosis, generating functions, Rényi entropy, Lorenz, Bonferroni and Zenga curves, probability weighted moment, stress strength model, order statistics, and record statistics. The model parameters were estimated by using the maximum likelihood criterion and the behaviours of these estimates were examined by conducting a simulation study. The applicability of the new model is illustrated by applying it on a real data set.

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A General Temperature-Dependent Stress–Strain Constitutive Model for Polymer-Bonded Composite Materials

Polymers ◽

10.3390/polym13091393 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1393

Author(s):

Xiaochang Duan ◽

Hongwei Yuan ◽

Wei Tang ◽

Jingjing He ◽

Xuefei Guan

Keyword(s):

Composite Materials ◽

Constitutive Model ◽

Model Parameters ◽

Temperature Dependent ◽

Stress Strain ◽

Proposed Model ◽

Single Temperature ◽

Testing Data ◽

Bonded Composite ◽

Tension And Compression

This study develops a general temperature-dependent stress–strain constitutive model for polymer-bonded composite materials, allowing for the prediction of deformation behaviors under tension and compression in the testing temperature range. Laboratory testing of the material specimens in uniaxial tension and compression at multiple temperatures ranging from −40 ∘C to 75 ∘C is performed. The testing data reveal that the stress–strain response can be divided into two general regimes, namely, a short elastic part followed by the plastic part; therefore, the Ramberg–Osgood relationship is proposed to build the stress–strain constitutive model at a single temperature. By correlating the model parameters with the corresponding temperature using a response surface, a general temperature-dependent stress–strain constitutive model is established. The effectiveness and accuracy of the proposed model are validated using several independent sets of testing data and third-party data. The performance of the proposed model is compared with an existing reference model. The validation and comparison results show that the proposed model has a lower number of parameters and yields smaller relative errors. The proposed constitutive model is further implemented as a user material routine in a finite element package. A simple structural example using the developed user material is presented and its accuracy is verified.

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