Drained Triaxial Compressive Shear Response of Cemented Paste Backfill (CPB)

Jafari, Mousa; Shahsavari, Mohammad; Grabinsky, Murray

doi:10.1007/s00603-021-02464-5

Cited by 29 publications

(7 citation statements)

References 49 publications

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“…This effect is quantified using consolidated drained triaxial test data in [23] where increasing the confining stress from 50 to 200 kPa increased the CPB's E t from about 25% for 5% binder content at 28-day cure time, to 100% for 2% binder content at 3-day cure time. Similar effects are shown in the consolidated drained triaxial test results for Williams CPB in [24].…”

Section: Obtaining Quality Test Datasupporting

confidence: 81%

“…Even if the effects of confinement on the elastic modulus and mobilized strength are accounted for, such strains must drive the CPB into its post-peak response. For example, drained triaxial tests were conducted by [23] with confinement 50-200 kPa on Shandong CPB, and by [24] with confinement 25-350 kPa on Williams CPB, and for the strongest materials tested by each, the axial strains to failure ranged from about 4% at the lowest confinement levels to 12% at the highest. Similarly, the authors of [40] interpreted 1-dimensional consolidation results in the context of ground reaction curves between CPB and the host rock during stope closure and concluded that the strains can essentially be ignored until the induced stress in the CPB reaches 2UCS, beyond which the stiffness increases exponentially and so too does the reaction.…”

Section: Implications For Mine Backfill Design Using Mitchell's Sill ...mentioning

confidence: 99%

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Cemented Paste Backfill (CPB) Material Properties for Undercut Analysis

Grabinsky

Jafari

Pan

2022

Mining

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A longstanding mine backfill design challenge is determining the strength required if the (partially) cured backfill is subsequently undercut. Mitchell (1991) called the undercut backfill a sill mat and proposed an analytical solution that is still often used, at least for preliminary design, and has motivated subsequent empirical design methods. However, fully employing the Mitchell sill mat solution requires knowledge of the backfill material’s Unconfined Compressive Strength (UCS), tangent Young’s modulus (Et), tensile strength (σt), as well as estimates of stope wall closure. Conducting a high-quality UCS test poses challenges but relating the test result to the remaining material parameters is more difficult. Some new material testing data is presented and compared to available published results. Using the parameter mi=UCS/σt the range of available testing data is found to be mi= 3 to 22, however, the most compelling data is obtained when the Mohr’s failure circle in tension is tangential to the corresponding Mohr–Coulomb failure envelope determined from other strength tests. In these cases, the value mi= 4 is found for the materials tested, which is much lower than the value mi= 10 commonly assumed and implies a limiting UCS 60% lower compared to the conventional assumption. It is also found that the relationship between Et and UCS is described by a power function that is close to linear, but the values for the constant and exponent in the power function depend on the material tested. However, for given tailings the power function is found to be independent of void ratio, binder type or concentration, curing time, and water salinity, within the ranges these parameters were investigated. Therefore, when Et is used in the Mitchell sill mat solution it should be correlated with the UCS using the appropriate power function. These correlations are then used with the Mitchell sill mat solution and published measurements of backfill closure strains to estimate the Mitchell solution’s range of applicability based on its underlying assumptions, and a similar analysis is extended to an “empirical design method” motivated by the Mitchell sill mat solution. It is demonstrated that these existing approaches have limited applicability, and more generally a full analysis in support of rational design will require numerical modeling that incorporates the effect of confining stress on the material’s stiffness and mobilized strength.

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Section: Obtaining Quality Test Datasupporting

confidence: 81%

Section: Implications For Mine Backfill Design Using Mitchell's Sill ...mentioning

confidence: 99%

Cemented Paste Backfill (CPB) Material Properties for Undercut Analysis

Grabinsky

Jafari

Pan

2022

Mining

Self Cite

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“…Mining activities and ore processing are closely linked by the generation of considerable volumes of underground voids and mine tailings, respectively (Benzaazoua et al, 2004;Hajkowicz et al, 2011). If not managed properly, these voids and tailings can bring about severe and long-term operational (e.g., ground or strata instability) (Jafari et al, 2021), environmental (e.g., heavy metal pollution) (Koohestani et al, 2018) and geotechnical risks (e.g., tailings dam failure and subsidence) (Rana et al, 2021). In recent years, technological progresses coupled with environmental regulation changes, including cemented paste backfill (CPB) system, have also triggered the development in tailings and voids management (Benzaazoua et al, 1999;Fall et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Strength Analysis and Optimization of Alkali Activated Slag Backfills Through Response Surface Methodology

Dai

Ren

et al. 2022

Front. Mater.

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The significant difference in water-to-binder ratio, activator type and concentration between alkali-activated slag (AAS) paste/mortar/concrete and AAS-based cemented paste backfill (AAS-CPB) means that previous results related to the properties and mix optimization of AAS materials cannot be directly translated to AAS-CPB. This study statistically identifies the effect of key influential variables such as silicate modulus, slag fineness and activator concentration on 3- and 28 day unconfined compressive strength (UCS) of AAS-CPB by central composite design (CCD) established in response surface methodology (RSM). In this study, the prominence of independent variables and their relations are investigated by using ANOVA (analysis of variance) having a significant level of 0.05. ANOVA results certify that there is a strong link between the level of variable contribution on UCS performance of AAS-CPB and curing age. Obviously, silicate modulus and activator concentration are the most major variables influencing UCS at 3 and 28 days, respectively. Increased fineness of slag and higher pH of pore solution enhance 3 day UCS, but restrain the further hydration of unreacted slag and subsequent the gain in strength at advanced curing ages. The combination of independent variables of silicate modulus (0.295), slag fineness (12630.2), activator concentration (0.45) gives the optimum responses.

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“…The simulation results expressed in stress, displacement and strain explained the influence of different parameters and evaluated the interaction between the filling material and surrounding rock to ensure the safe application of the filling material. The above research on the combined action of surrounding rock and backfill mainly involved their mechanical action mechanism and only studied the failure law, without considering the synergistic effect, and thus the damage constitutive model was established [29][30][31][32]. The surrounding rock and backfill were regarded as independent individuals and studied their roles under different combination structure modes, respectively.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Analytical Investigation into the Synergistic Mechanism and Failure Characteristics of the Backfill-Red Sandstone Combination

et al. 2022

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The stability of underground goaf in filling mining is dominated by the interaction mechanism of the backfill-surrounding rock combination. In order to investigate the interaction mechanism and failure characteristics of the backfill-surrounding rock combination, backfill-red sandstone combinations with three different cement–sand ratios were prepared for uniaxial compression tests. The deformation and failure characteristics of the specimens were analyzed. It was found that at the cement–sand ratio of 1:4, the backfill and red sandstone interacted with and restricted each other, and the through cracks appeared in the whole specimens, which indicated that the backfill and red sandstone can jointly resist external loads and play a role in common bearing. However, with the decrease of the cement–sand ratio, the stress mainly acts on the backfill, and the deformation observed in the backfill is large while there is no obvious rupture in the rock. Based on the failure characteristics and the stress–strain curves of the specimens, the damage constitutive relationship that can describe the failure process and deformation characteristics is proposed. Correlated with the experiment results, the damage constitutive equation is established in three stages including compaction pre-synergy stage, quasi-elastic synergy deformation stage and rupture deformation stage. The failure characteristics observed in each stage are analyzed. The research results are of great significance to accurately understanding the interaction between backfill and surrounding rock, which can be used to design and select the mixture ratio of the filling materials.

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Drained Triaxial Compressive Shear Response of Cemented Paste Backfill (CPB)

Cited by 29 publications

References 49 publications

Cemented Paste Backfill (CPB) Material Properties for Undercut Analysis

Cemented Paste Backfill (CPB) Material Properties for Undercut Analysis

Strength Analysis and Optimization of Alkali Activated Slag Backfills Through Response Surface Methodology

Experimental and Analytical Investigation into the Synergistic Mechanism and Failure Characteristics of the Backfill-Red Sandstone Combination

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