Pub Date : 2021-01-01DOI: 10.12989/GAE.2021.24.3.227
V. Mirsalimov
A criterion and a method for solving a problem on the prevention of mine working fracture under the action of tectonic and gravitational forces are offered. Based on minimal criterion, theoretical analysis of the definition of the optimal shape of working in the rock mass weakened by arbitrarily located rectilinear cracks was carried out. A closed system of algebraic equations allowing to minimize the stress state and stress intensity factors depending on mechanical and geometrical characteristics of the rock, is constructed. The relation between the shape of the working and the stress intensity factors and also location and sizes of the cracks is obtained. The found optimal shape of working increases load-bearing capacity of the rock.
{"title":"Optimal design of shape of a working in cracked rock mass","authors":"V. Mirsalimov","doi":"10.12989/GAE.2021.24.3.227","DOIUrl":"https://doi.org/10.12989/GAE.2021.24.3.227","url":null,"abstract":"A criterion and a method for solving a problem on the prevention of mine working fracture under the action of tectonic and gravitational forces are offered. Based on minimal criterion, theoretical analysis of the definition of the optimal shape of working in the rock mass weakened by arbitrarily located rectilinear cracks was carried out. A closed system of algebraic equations allowing to minimize the stress state and stress intensity factors depending on mechanical and geometrical characteristics of the rock, is constructed. The relation between the shape of the working and the stress intensity factors and also location and sizes of the cracks is obtained. The found optimal shape of working increases load-bearing capacity of the rock.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":"24 1","pages":"227-235"},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66472396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/GAE.2021.24.4.371
Worathep Sae-Long, S. Limkatanyu, C. Hansapinyo, Woraphot Prachasaree, J. Rungamornrat, M. Kwon
A novel flexibility-based beam-foundation model for inelastic analyses of beams resting on foundation is presented in this paper. To model the deformability of supporting foundation media, the Winkler-Pasternak foundation model is adopted. Following the derivation of basic equations of the problem (strong form), the flexibility-based finite beam-foundation element (weak form) is formulated within the framework of the matrix virtual force principle. Through equilibrated force shape functions, the internal force fields are related to the element force degrees of freedom. Tonti's diagrams are adopted to present both strong and weak forms of the problem. Three numerical simulations are employed to assess validity and to show effectiveness of the proposed flexibility-based beam-foundation model. The first two simulations focus on elastic beam-foundation systems while the last simulation emphasizes on an inelastic beam-foundation system. The influences of the adopted foundation model to represent the underlying foundation medium are also discussed.
{"title":"Nonlinear flexibility-based beam element on Winkler-Pasternak foundation","authors":"Worathep Sae-Long, S. Limkatanyu, C. Hansapinyo, Woraphot Prachasaree, J. Rungamornrat, M. Kwon","doi":"10.12989/GAE.2021.24.4.371","DOIUrl":"https://doi.org/10.12989/GAE.2021.24.4.371","url":null,"abstract":"A novel flexibility-based beam-foundation model for inelastic analyses of beams resting on foundation is presented in this paper. To model the deformability of supporting foundation media, the Winkler-Pasternak foundation model is adopted. Following the derivation of basic equations of the problem (strong form), the flexibility-based finite beam-foundation element (weak form) is formulated within the framework of the matrix virtual force principle. Through equilibrated force shape functions, the internal force fields are related to the element force degrees of freedom. Tonti's diagrams are adopted to present both strong and weak forms of the problem. Three numerical simulations are employed to assess validity and to show effectiveness of the proposed flexibility-based beam-foundation model. The first two simulations focus on elastic beam-foundation systems while the last simulation emphasizes on an inelastic beam-foundation system. The influences of the adopted foundation model to represent the underlying foundation medium are also discussed.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":"24 1","pages":"371"},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66472537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/GAE.2021.24.4.349
Jiong Wei, Jingren Zhou, Jae-Joon Song, Yulong Chen, P. Kulatilake
The Brazilian test has been widely used to determine the indirect tensile strength of rock, concrete and other brittle materials. The basic assumption for the calculation formula of Brazilian tensile strength is that the elastic moduli of rock are the same both in tension and compression. However, the fact is that the elastic moduli in tension and compression of most rocks are different. Thus, the formula of Brazilian tensile strength under the assumption of isotropy is unreasonable. In the present study, we conducted Brazilian tests on flat disk-shaped rock specimens and attached strain gauges at the center of the disc to measure the strains of rock. A tension-compression bi-modular model is proposed to interpret the data of the Brazilian test. The relations between the principal strains, principal stresses and the ratio of the compressive modulus to tensile modulus at the disc center are established. Thus, the tensile and compressive moduli as well as the correct tensile strength can be estimated simultaneously by the new formulas. It is found that the tensile and compressive moduli obtained using these formulas were in well agreement with the values obtained from the direct tension and compression tests. The formulas deduced from the Brazilian test based on the assumption of isotropy overestimated the tensile strength and tensile modulus and underestimated the compressive modulus. This work provides a new methodology to estimate tensile strength and moduli of rock simultaneously considering tension-compression bi-modularity.
{"title":"Estimation of tensile strength and moduli of a tension-compression bi-modular rock","authors":"Jiong Wei, Jingren Zhou, Jae-Joon Song, Yulong Chen, P. Kulatilake","doi":"10.12989/GAE.2021.24.4.349","DOIUrl":"https://doi.org/10.12989/GAE.2021.24.4.349","url":null,"abstract":"The Brazilian test has been widely used to determine the indirect tensile strength of rock, concrete and other brittle materials. The basic assumption for the calculation formula of Brazilian tensile strength is that the elastic moduli of rock are the same both in tension and compression. However, the fact is that the elastic moduli in tension and compression of most rocks are different. Thus, the formula of Brazilian tensile strength under the assumption of isotropy is unreasonable. In the present study, we conducted Brazilian tests on flat disk-shaped rock specimens and attached strain gauges at the center of the disc to measure the strains of rock. A tension-compression bi-modular model is proposed to interpret the data of the Brazilian test. The relations between the principal strains, principal stresses and the ratio of the compressive modulus to tensile modulus at the disc center are established. Thus, the tensile and compressive moduli as well as the correct tensile strength can be estimated simultaneously by the new formulas. It is found that the tensile and compressive moduli obtained using these formulas were in well agreement with the values obtained from the direct tension and compression tests. The formulas deduced from the Brazilian test based on the assumption of isotropy overestimated the tensile strength and tensile modulus and underestimated the compressive modulus. This work provides a new methodology to estimate tensile strength and moduli of rock simultaneously considering tension-compression bi-modularity.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":"24 1","pages":"349"},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66472870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/GAE.2021.24.6.519
W. Kai, Guo Yangyang, Hao Xu, Dong Huzi, Feng-Lei Du, Qiming Huang
{"title":"Deformation and permeability evolution of coal during axial stress cyclic loading and unloading: An experimental study","authors":"W. Kai, Guo Yangyang, Hao Xu, Dong Huzi, Feng-Lei Du, Qiming Huang","doi":"10.12989/GAE.2021.24.6.519","DOIUrl":"https://doi.org/10.12989/GAE.2021.24.6.519","url":null,"abstract":"","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":"129 1","pages":"519"},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66475405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/GAE.2021.25.6.521
Biao Zhang, Jinquan Jiang, Dao-bing Zhang, Ze Liu
This work presents seismic stability analysis of tunnel faces under three-dimensional (3D) conditions. To consider the temporal and spatial features of seismic force, the pseudo-dynamic approach was employed and incorporated into the 'horn-like' mechanism. According to the limit analysis method and the Hoek-Brown strength criterion, analytical solution of collapse pressure on tunnel faces was derived. The permanent displacement of tunnel face was then calculated by virtue of the Newmark method. The effects of the parameters of seismic force and Hoek-Brown strength criterion on collapse pressure and failure range of tunnel faces were analyzed. The relationship between the Hoek-Brown strength criterion parameters, the supporting force, and the yield acceleration was discussed. Moreover, the permanent displacements at the top, center, and bottom of tunnel faces under seismic effect were examined. This paper proposes a new idea for seismic stability analysis of tunnel faces.
{"title":"Upper bound solution of collapse pressure and permanent displacement of 3D tunnel faces using the pseudo-dynamic method and the kinematic approach","authors":"Biao Zhang, Jinquan Jiang, Dao-bing Zhang, Ze Liu","doi":"10.12989/GAE.2021.25.6.521","DOIUrl":"https://doi.org/10.12989/GAE.2021.25.6.521","url":null,"abstract":"This work presents seismic stability analysis of tunnel faces under three-dimensional (3D) conditions. To consider the temporal and spatial features of seismic force, the pseudo-dynamic approach was employed and incorporated into the 'horn-like' mechanism. According to the limit analysis method and the Hoek-Brown strength criterion, analytical solution of collapse pressure on tunnel faces was derived. The permanent displacement of tunnel face was then calculated by virtue of the Newmark method. The effects of the parameters of seismic force and Hoek-Brown strength criterion on collapse pressure and failure range of tunnel faces were analyzed. The relationship between the Hoek-Brown strength criterion parameters, the supporting force, and the yield acceleration was discussed. Moreover, the permanent displacements at the top, center, and bottom of tunnel faces under seismic effect were examined. This paper proposes a new idea for seismic stability analysis of tunnel faces.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":"6 1","pages":"521"},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66477394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/GAE.2021.26.1.013
Aysan Poorjafar, M. Esmaeili‐Falak, H. Katebi
This paper summarizes the results of small-scale laboratory modelling of pile behavior under lateral loading, considering the parameters such as short or long, single or group, spacing and rigidity or flexibility of piles. The head of piles was fixedly connected to the cap. In addition, the PIV method has been used to examine the effect of the mentioned parameters on the failure mechanism and pile-soil interaction more accurately. The results show that the short piles have a rigid movement, the displacement of the surrounding soil has occurred along the total length of the pile and the piles rotate around a point but the long piles have a flexible movement at the part of the pile length. It seems that the group effect be more obvious for long piles than short piles. Also, the effective depth of total soil displacement vectors around the trail pile is more than the lead one in long pile group, while this depth for trail pile is less than the lead pile in short pile group. Due to the sharper angles of total displacement vectors around the trail pile, the intensity of soil shear strains around the trail pile is greater than the lead pile.
{"title":"Pile-soil interaction determined by laterally loaded fixed head pile group","authors":"Aysan Poorjafar, M. Esmaeili‐Falak, H. Katebi","doi":"10.12989/GAE.2021.26.1.013","DOIUrl":"https://doi.org/10.12989/GAE.2021.26.1.013","url":null,"abstract":"This paper summarizes the results of small-scale laboratory modelling of pile behavior under lateral loading, considering the parameters such as short or long, single or group, spacing and rigidity or flexibility of piles. The head of piles was fixedly connected to the cap. In addition, the PIV method has been used to examine the effect of the mentioned parameters on the failure mechanism and pile-soil interaction more accurately. The results show that the short piles have a rigid movement, the displacement of the surrounding soil has occurred along the total length of the pile and the piles rotate around a point but the long piles have a flexible movement at the part of the pile length. It seems that the group effect be more obvious for long piles than short piles. Also, the effective depth of total soil displacement vectors around the trail pile is more than the lead one in long pile group, while this depth for trail pile is less than the lead pile in short pile group. Due to the sharper angles of total displacement vectors around the trail pile, the intensity of soil shear strains around the trail pile is greater than the lead pile.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":"26 1","pages":"13"},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66477521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/GAE.2021.26.2.205
Zhen-Hua Xin, Jun-Ho Moon, Kab-Boo Kim, Changrok Kim, Young-Uk Kim
To maintain the stability of built structures, engineers employ various methods to increase ground strength. One such method is to exert mutual physical force upon a structure, thereby stabilizing it without external reinforcement. Typical examples include the stone mastic asphalt method and torsional structured stonework. By simulating a structural phenomenon, it is possible to increase the ground's strength simply by manipulating the distribution and spatial arrangement of soil particles; soil composed of two differently sized particles satisfying a specific ratio does not separate easily. The jamming of soil particles utilizes Plato
{"title":"Effect of underground stress transfer through artificial manipulation of particle size distribution","authors":"Zhen-Hua Xin, Jun-Ho Moon, Kab-Boo Kim, Changrok Kim, Young-Uk Kim","doi":"10.12989/GAE.2021.26.2.205","DOIUrl":"https://doi.org/10.12989/GAE.2021.26.2.205","url":null,"abstract":"To maintain the stability of built structures, engineers employ various methods to increase ground strength. One such method is to exert mutual physical force upon a structure, thereby stabilizing it without external reinforcement. Typical examples include the stone mastic asphalt method and torsional structured stonework. By simulating a structural phenomenon, it is possible to increase the ground's strength simply by manipulating the distribution and spatial arrangement of soil particles; soil composed of two differently sized particles satisfying a specific ratio does not separate easily. The jamming of soil particles utilizes Plato","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":"26 1","pages":"205"},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66478020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/GAE.2021.26.2.147
Byeong-Su Kim
Direct shear test has been widely used to examine the shear strength of geomaterials because of the simplicity of the testing method and apparatus. Three factors significantly affect the accuracy of the experimental results of direct shear tests, namely (1) the type of direct shear apparatus, (2) the specimen size (scale effect), and (3) the opening size between shear boxes. This study focused on the Threshold Line (TL), which is obtained based on experimental tests, as a guideline for setting the opening size between the shear boxes. The validity of the TL was examined using distinct element method (DEM) 3D simulations from the following four perspectives: the first and second perspectives investigated the influence of the mean particle size and particle size distribution for mean particle sizes larger than 0.8 mm. In the third perspective, the scale effect of the specimens for fixed and varying D:H ratios of the shear box to reduce the shear box size was examined. Lastly, in the fourth perspective, the validity of using the TL to determine the appropriate opening size for the samples with a mean particle size smaller than 0.8 mm was also examined based on the Threshold Point (TP). For each case, the results of the TPs obtained from the DEM simulations agreed well with those of the TL. These findings suggest that the TL is valid and the TL relational equation can be used for setting the opening size between the shear boxes in the direct shear test regardless of saturated and unsaturated soils.
{"title":"Establishing an opening size criterion in direct shear test using DEM Simulation","authors":"Byeong-Su Kim","doi":"10.12989/GAE.2021.26.2.147","DOIUrl":"https://doi.org/10.12989/GAE.2021.26.2.147","url":null,"abstract":"Direct shear test has been widely used to examine the shear strength of geomaterials because of the simplicity of the testing method and apparatus. Three factors significantly affect the accuracy of the experimental results of direct shear tests, namely (1) the type of direct shear apparatus, (2) the specimen size (scale effect), and (3) the opening size between shear boxes. This study focused on the Threshold Line (TL), which is obtained based on experimental tests, as a guideline for setting the opening size between the shear boxes. The validity of the TL was examined using distinct element method (DEM) 3D simulations from the following four perspectives: the first and second perspectives investigated the influence of the mean particle size and particle size distribution for mean particle sizes larger than 0.8 mm. In the third perspective, the scale effect of the specimens for fixed and varying D:H ratios of the shear box to reduce the shear box size was examined. Lastly, in the fourth perspective, the validity of using the TL to determine the appropriate opening size for the samples with a mean particle size smaller than 0.8 mm was also examined based on the Threshold Point (TP). For each case, the results of the TPs obtained from the DEM simulations agreed well with those of the TL. These findings suggest that the TL is valid and the TL relational equation can be used for setting the opening size between the shear boxes in the direct shear test regardless of saturated and unsaturated soils.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":"26 1","pages":"147"},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66478101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/GAE.2021.26.5.415
Hong-lue Qu, Deng Yuanyuan, Qindi Hu, H. Xue, Wang Chenxu
According to the results of a survey of retaining structures damaged by the Wenchuan earthquake, the damage to gravity retaining walls accounted for 97.1% of the total damage to retaining walls. Among gravity retaining structures, embankment gravity retaining walls with nonuniform slopes are more prone to be disturbed under seismic conditions. However, relatively few studies have been performed to calculate the seismic earth pressure on such structures. In this study, a simplified approach is presented to calculate the seismic earth pressure on embankment gravity retaining walls with nonuniform slopes. In the proposed approach, the equations are derived based on the primary assumptions of the Mononobe–Okabe theory and the limit equilibrium state of the quadrilateral slip soil wedge. To verify the applicability of the proposed approach, a large-scale shaking-table test was conducted to obtain the distribution of the seismic earth pressure, the magnitude of earth pressure resultant force, the resultant force action point, and slip surface of an embankment gravity retaining wall with a nonuniform slope, under various peak ground accelerations. A comparison indicates that the calculated results were in agreement with the experimental results, implying that the proposed approach is valid for calculating the seismic earth pressure on embankment gravity retaining walls with nonuniform slopes.
{"title":"Seismic earth pressure on embankment gravity retaining wall with nonuniform slope","authors":"Hong-lue Qu, Deng Yuanyuan, Qindi Hu, H. Xue, Wang Chenxu","doi":"10.12989/GAE.2021.26.5.415","DOIUrl":"https://doi.org/10.12989/GAE.2021.26.5.415","url":null,"abstract":"According to the results of a survey of retaining structures damaged by the Wenchuan earthquake, the damage to gravity retaining walls accounted for 97.1% of the total damage to retaining walls. Among gravity retaining structures, embankment gravity retaining walls with nonuniform slopes are more prone to be disturbed under seismic conditions. However, relatively few studies have been performed to calculate the seismic earth pressure on such structures. In this study, a simplified approach is presented to calculate the seismic earth pressure on embankment gravity retaining walls with nonuniform slopes. In the proposed approach, the equations are derived based on the primary assumptions of the Mononobe–Okabe theory and the limit equilibrium state of the quadrilateral slip soil wedge. To verify the applicability of the proposed approach, a large-scale shaking-table test was conducted to obtain the distribution of the seismic earth pressure, the magnitude of earth pressure resultant force, the resultant force action point, and slip surface of an embankment gravity retaining wall with a nonuniform slope, under various peak ground accelerations. A comparison indicates that the calculated results were in agreement with the experimental results, implying that the proposed approach is valid for calculating the seismic earth pressure on embankment gravity retaining walls with nonuniform slopes.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":"26 1","pages":"415"},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66479126","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/GAE.2021.26.5.499
El Mustapha Jaouhara, Jian Zheng, Li Li
Mining backfill is increasingly used in underground mines to fill stopes. Its successful application depends on the stability of barricades built to retain the backfill in stopes. The design of barricades requires a good estimation of pore water pressure (PWP) and total stresses during and after the deposition. On this regard, a large number of works have been published on analytical and numerical solutions. There are however very few experimental results with simultaneous measurements of PWP as well as horizontal and vertical total stresses that can be used to validate or calibrate the analytical and numerical solutions. For a specific project, field measurements are interesting in terms of representativeness to field conditions, but the results are very difficult to be correctly interpreted because the treated problem can involve a large number of uncertainties and the obtained results are due to combined effects of several influencing factors. Laboratory tests with simplified and well-controlled conditions are thus preferred. Until now, however, the most previous laboratory tests were conducted with dry backfill or with a tailings slurry instantaneously poured in a confining structure without simultaneous measurements of PWP as well as horizontal and vertical total stresses. Studies on the effects of filling rate and solid content of backfill on the variation of PWP and total stresses during the filling operation are absent. To fill these gaps, a series of column backfilling tests were conducted with simultaneous measurements of PWP as well as vertical and horizontal total stresses during and after the deposition of slurried backfill. When the filling rate is high, the test results showed that the PWP, horizontal and vertical total stresses increase at the same rate and equal to the iso-geostatic overburden pressure during the deposition of backfill slurry. Their peak values appear at the end of deposition. The backfill thus behaves like a liquid with little generation of effective stresses during the deposition. High filling rate and/or high solid content lead to high PWP and horizontal total stresses at the end of deposition. When the filling rate is small, the PWP and total stresses exhibit also peak values at the end of filling operation, but the vertical total stress at the center can continue increasing with time after the end of deposition due to the suspended sensor and occurrence of a phenomenon known as stress shielding effect. The results also showed that the settlement of settled backfill after the end of slurry deposition can generally exhibits a fast evolution rate stage, followed by a slow evolution rate stage. The duration of the fast evolution rate stage and the final settlement of the settled backfill increase as the solid content decreases. The final settlement after the end of slurry deposition is related to the solid content, not to the filling rate.
{"title":"Experimental study of the evolution of pore water pressure and total stresses during and after the deposition of slurried backfill","authors":"El Mustapha Jaouhara, Jian Zheng, Li Li","doi":"10.12989/GAE.2021.26.5.499","DOIUrl":"https://doi.org/10.12989/GAE.2021.26.5.499","url":null,"abstract":"Mining backfill is increasingly used in underground mines to fill stopes. Its successful application depends on the stability of barricades built to retain the backfill in stopes. The design of barricades requires a good estimation of pore water pressure (PWP) and total stresses during and after the deposition. On this regard, a large number of works have been published on analytical and numerical solutions. There are however very few experimental results with simultaneous measurements of PWP as well as horizontal and vertical total stresses that can be used to validate or calibrate the analytical and numerical solutions. For a specific project, field measurements are interesting in terms of representativeness to field conditions, but the results are very difficult to be correctly interpreted because the treated problem can involve a large number of uncertainties and the obtained results are due to combined effects of several influencing factors. Laboratory tests with simplified and well-controlled conditions are thus preferred. Until now, however, the most previous laboratory tests were conducted with dry backfill or with a tailings slurry instantaneously poured in a confining structure without simultaneous measurements of PWP as well as horizontal and vertical total stresses. Studies on the effects of filling rate and solid content of backfill on the variation of PWP and total stresses during the filling operation are absent. To fill these gaps, a series of column backfilling tests were conducted with simultaneous measurements of PWP as well as vertical and horizontal total stresses during and after the deposition of slurried backfill. When the filling rate is high, the test results showed that the PWP, horizontal and vertical total stresses increase at the same rate and equal to the iso-geostatic overburden pressure during the deposition of backfill slurry. Their peak values appear at the end of deposition. The backfill thus behaves like a liquid with little generation of effective stresses during the deposition. High filling rate and/or high solid content lead to high PWP and horizontal total stresses at the end of deposition. When the filling rate is small, the PWP and total stresses exhibit also peak values at the end of filling operation, but the vertical total stress at the center can continue increasing with time after the end of deposition due to the suspended sensor and occurrence of a phenomenon known as stress shielding effect. The results also showed that the settlement of settled backfill after the end of slurry deposition can generally exhibits a fast evolution rate stage, followed by a slow evolution rate stage. The duration of the fast evolution rate stage and the final settlement of the settled backfill increase as the solid content decreases. The final settlement after the end of slurry deposition is related to the solid content, not to the filling rate.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":"80 1","pages":"499"},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66479922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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