Pub Date : 2021-01-01DOI: 10.12989/GAE.2021.27.1.013
Tong Yu, H. Souli, Y. Péchaud, J. Fleureau
Microbial induced calcium carbonate precipitation (MICP), a sustainable and effective soil improvement method, has experienced a burgeoning development in recent years. It is a bio-mediated method that uses the metabolic process of bacteria to cause CaCO3 precipitation in the pore space of the soil. This technique has a large potential in the geotechnical engineering field to enhance soil properties, including mitigation of liquefaction, control of suffusion, etc. Multi-scale studies, from microstructure investigations (microscopic imaging and related rising techniques at micron-scale), to macroscopic tests (lab-based physical, chemical and mechanical tests from centimeter to meter), to in-situ trials (kilometers), have been done to study the mechanisms and efficiency of MICP. In this article, results obtained in recent years from various testing methods (conventional tests including unconfined compression tests, triaxial and oedometric tests, centrifuge tests, shear wave velocity and permeability measurements, as well as microscopic imaging) were selected, presented, analyzed and summarized, in order to be used as reference for future studies. Though results obtained in various studies are rather scattered, owning to the different experimental conditions, general conclusions can be given: when the CaCO3 content (CCC) increases, the unconfined compression strength increases (up to 1.4 MPa for CCC=5%) as well as the shear wave velocity (more than 1-fold increase in V_s for each 1% CaCO3 precipitated), and the permeability decreases (with a drop limited to less than 3 orders of magnitude). Concerning the mechanical behavior of MICP treated soil, an increase in the peak properties, an indefinite increase in friction angle and a large increase in cohesion were obtained. When the soil was subjected to cyclic/dynamic loadings, lower pore pressure generation, reduced strains, and increasing number of cycles to reach liquefaction were concluded. It is important to note that the formation of CaCO3 results in an increase in the dry density of the samples, which adds to the bonding of particles and may play a major part in the improvement of the mechanical properties of soil, such as peak maximum deviator, resistance to liquefaction, etc.
{"title":"Review on engineering properties of MICP-treated soils","authors":"Tong Yu, H. Souli, Y. Péchaud, J. Fleureau","doi":"10.12989/GAE.2021.27.1.013","DOIUrl":"https://doi.org/10.12989/GAE.2021.27.1.013","url":null,"abstract":"Microbial induced calcium carbonate precipitation (MICP), a sustainable and effective soil improvement method, has experienced a burgeoning development in recent years. It is a bio-mediated method that uses the metabolic process of bacteria to cause CaCO3 precipitation in the pore space of the soil. This technique has a large potential in the geotechnical engineering field to enhance soil properties, including mitigation of liquefaction, control of suffusion, etc. Multi-scale studies, from microstructure investigations (microscopic imaging and related rising techniques at micron-scale), to macroscopic tests (lab-based physical, chemical and mechanical tests from centimeter to meter), to in-situ trials (kilometers), have been done to study the mechanisms and efficiency of MICP. In this article, results obtained in recent years from various testing methods (conventional tests including unconfined compression tests, triaxial and oedometric tests, centrifuge tests, shear wave velocity and permeability measurements, as well as microscopic imaging) were selected, presented, analyzed and summarized, in order to be used as reference for future studies. Though results obtained in various studies are rather scattered, owning to the different experimental conditions, general conclusions can be given: when the CaCO3 content (CCC) increases, the unconfined compression strength increases (up to 1.4 MPa for CCC=5%) as well as the shear wave velocity (more than 1-fold increase in V_s for each 1% CaCO3 precipitated), and the permeability decreases (with a drop limited to less than 3 orders of magnitude). Concerning the mechanical behavior of MICP treated soil, an increase in the peak properties, an indefinite increase in friction angle and a large increase in cohesion were obtained. When the soil was subjected to cyclic/dynamic loadings, lower pore pressure generation, reduced strains, and increasing number of cycles to reach liquefaction were concluded. It is important to note that the formation of CaCO3 results in an increase in the dry density of the samples, which adds to the bonding of particles and may play a major part in the improvement of the mechanical properties of soil, such as peak maximum deviator, resistance to liquefaction, etc.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":"152 7 1","pages":"13-30"},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66480980","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.2021.26.4.323
S. Chaiyaput, J. Ayawanna
The effect of ladle furnace slag or LFS on the mechanical properties of the lateritic soil mixes for use as a subbase course material in the pavement structure was investigated. The lateritic soil grade E with the lowest mechanical properties was studied by mixing the LFS in the ratios of 5 to 12 wt%. The pavement material criterion of the Thailand Department of Highways was used to qualify the liquid limit, plasticity index, the California bearing ratio, and the swelling index of the mixed lateritic soil with the LFS. An increase in the California bearing ratio of the lateritic soil under the soaked condition was found to be positively correlated with the increasing LFS. Meanwhile, the liquid limit and the plasticity index decreased, leading to a decrease in the swelling index of the lateritic soil containing LFS. Using LFS reduced the total fine-particle ratio in the soil mixture but effectively enhanced the degree of compaction and swelling tolerance in the lateritic soil mixture. 10 wt% LFS is strongly recommended as a minimum admixture in the lateritic soil due to the highly improved plasticity and the mechanical properties of the lateritic soil for a subbase course material selection under the standard specifications.
{"title":"Stabilization of lateritic soil by ladle furnace slag for pavement subbase material","authors":"S. Chaiyaput, J. Ayawanna","doi":"10.12989/GAE.2021.26.4.323","DOIUrl":"https://doi.org/10.12989/GAE.2021.26.4.323","url":null,"abstract":"The effect of ladle furnace slag or LFS on the mechanical properties of the lateritic soil mixes for use as a subbase course material in the pavement structure was investigated. The lateritic soil grade E with the lowest mechanical properties was studied by mixing the LFS in the ratios of 5 to 12 wt%. The pavement material criterion of the Thailand Department of Highways was used to qualify the liquid limit, plasticity index, the California bearing ratio, and the swelling index of the mixed lateritic soil with the LFS. An increase in the California bearing ratio of the lateritic soil under the soaked condition was found to be positively correlated with the increasing LFS. Meanwhile, the liquid limit and the plasticity index decreased, leading to a decrease in the swelling index of the lateritic soil containing LFS. Using LFS reduced the total fine-particle ratio in the soil mixture but effectively enhanced the degree of compaction and swelling tolerance in the lateritic soil mixture. 10 wt% LFS is strongly recommended as a minimum admixture in the lateritic soil due to the highly improved plasticity and the mechanical properties of the lateritic soil for a subbase course material selection under the standard specifications.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":"26 1","pages":"323"},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66478958","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.2021.24.2.143
Xuan Ding, Li-ming Qu, Jin-chuan Yang, Chenglong Wang
Rail transit lines usually pass through many complicated topographies in mountain areas. The influence of inclined bedrock on the train-induced soil vibration response was investigated. Model tests were conducted to comparatively analyze the vibration attenuation under inclined bedrock and horizontal bedrock conditions. A three-dimension numerical model was built to make parameter analysis. The results show that under the horizontal bedrock condition, the peak velocity in different directions was almost the same, while it obviously changed under the inclined bedrock condition. Further, the peak velocity under inclined bedrock condition had a larger value. The peak velocity first increased and then decreased with depth, and the trend of the curve of vibration attenuation with depth presented as a quadratic parabola. The terrain conditions had a significant influence on the vibration responses, and the inclined soil surface mainly affected the shallow soil. The influence of the dip angle of bedrock on the peak velocity and vibration attenuation was related to the directions of the ground surface. As the soil thickness increased, the peak velocity decreased, and as it reached 173% of the embedded pile length, the influence of the inclined bedrock could be neglected.
{"title":"Soil vibration induced by railway traffic around a pile under the inclined bedrock condition","authors":"Xuan Ding, Li-ming Qu, Jin-chuan Yang, Chenglong Wang","doi":"10.12989/GAE.2021.24.2.143","DOIUrl":"https://doi.org/10.12989/GAE.2021.24.2.143","url":null,"abstract":"Rail transit lines usually pass through many complicated topographies in mountain areas. The influence of inclined bedrock on the train-induced soil vibration response was investigated. Model tests were conducted to comparatively analyze the vibration attenuation under inclined bedrock and horizontal bedrock conditions. A three-dimension numerical model was built to make parameter analysis. The results show that under the horizontal bedrock condition, the peak velocity in different directions was almost the same, while it obviously changed under the inclined bedrock condition. Further, the peak velocity under inclined bedrock condition had a larger value. The peak velocity first increased and then decreased with depth, and the trend of the curve of vibration attenuation with depth presented as a quadratic parabola. The terrain conditions had a significant influence on the vibration responses, and the inclined soil surface mainly affected the shallow soil. The influence of the dip angle of bedrock on the peak velocity and vibration attenuation was related to the directions of the ground surface. As the soil thickness increased, the peak velocity decreased, and as it reached 173% of the embedded pile length, the influence of the inclined bedrock could be neglected.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":"24 1","pages":"143"},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66472075","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.2021.24.2.193
Saif Alzabeebee
The time-history finite element analysis is usually used to evaluate the seismic response of shallow foundations. However, the literature lacks studies on the influence of the soil constitutive model complexity on the seismic response of shallow foundations. This study, thus, aims to fill this gap by investigating the seismic response of shallow foundation resting on dry silica sand using the linear elastic (LE) model, elastic-perfectly-plastic (EPP) model, and hardening soil with small strain stiffness (HS small) model. These models have been used because it is intended to compare the results of a soil constitutive model that accurately captures the seismic response of the soil-structure interaction problems (which is the HS small model) with simpler models (the LE and EPP models) that are routinely used by practitioners in geotechnical designs. The results showed that the LE model produces a very small seismic settlement value which is approximately equal to zero. The EPP model predicts a seismic settlement higher than that produced using the HS small model for earthquakes with a peak ground acceleration (PGA) lower than 0.25 g for a relative density of 45% and 0.40 g for a relative density of 70%. However, the HS small model predicts a seismic settlement higher than the EPP model beyond the aforementioned PGA values with the difference between both models increases as the PGA rises. The results also showed that the LE and EPP models predict similar trend and magnitude of the acceleration-time relationship directly below the foundation, which was different than that predicted using the HS small model. The results reported in this paper provide a useful benchmark for future numerical studies on the response of shallow foundations subjected to seismic shake.
{"title":"Influence of soil model complexity on the seismic response of shallow foundations","authors":"Saif Alzabeebee","doi":"10.12989/GAE.2021.24.2.193","DOIUrl":"https://doi.org/10.12989/GAE.2021.24.2.193","url":null,"abstract":"The time-history finite element analysis is usually used to evaluate the seismic response of shallow foundations. However, the literature lacks studies on the influence of the soil constitutive model complexity on the seismic response of shallow foundations. This study, thus, aims to fill this gap by investigating the seismic response of shallow foundation resting on dry silica sand using the linear elastic (LE) model, elastic-perfectly-plastic (EPP) model, and hardening soil with small strain stiffness (HS small) model. These models have been used because it is intended to compare the results of a soil constitutive model that accurately captures the seismic response of the soil-structure interaction problems (which is the HS small model) with simpler models (the LE and EPP models) that are routinely used by practitioners in geotechnical designs. The results showed that the LE model produces a very small seismic settlement value which is approximately equal to zero. The EPP model predicts a seismic settlement higher than that produced using the HS small model for earthquakes with a peak ground acceleration (PGA) lower than 0.25 g for a relative density of 45% and 0.40 g for a relative density of 70%. However, the HS small model predicts a seismic settlement higher than the EPP model beyond the aforementioned PGA values with the difference between both models increases as the PGA rises. The results also showed that the LE and EPP models predict similar trend and magnitude of the acceleration-time relationship directly below the foundation, which was different than that predicted using the HS small model. The results reported in this paper provide a useful benchmark for future numerical studies on the response of shallow foundations subjected to seismic shake.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":"24 1","pages":"193"},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66472198","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.2021.25.1.031
Minhyeong Lee, J. Im, I. Chang, G. Cho
Injection grouting is one of the most common ground improvement practice to increase the strength and reduce the hydraulic conductivity of soils. Owing to the environmental concerns of conventional grout materials, such as cement-based or silicate-based materials, bio-inspired biogeotechnical approaches are considered to be new sustainable and environmentally friendly ground improvement methods. Biopolymers, which are excretory products from living organisms, have been shown to significantly reduce the hydraulic conductivity via pore-clogging and increase the strength of soils. To study the practical application of biopolymers for seepage and ground water control, in this study, we explored the injection capabilities of biopolymer-based grout materials in both linear aperture and particulate media (i.e., sand and glassbeads) considering different injection pressures, biopolymer concentrations, and flow channel geometries. The hydraulic conductivity control of a biopolymer-based grout material was evaluated after injection into sandy soil under confined boundary conditions. The results showed that the performance of xanthan gum injection was mainly affected by the injection pressure and pore geometry (e.g., porosity) inside the soil. Additionally, with an increase in the xanthan gum concentration, the injection efficiency diminished while the hydraulic conductivity reduction efficiency enhanced significantly. The results of this study provide the potential capabilities of injection grouting to be performed with biopolymer-based materials for field application.
{"title":"Evaluation of Injection capabilities of a biopolymer-based grout material","authors":"Minhyeong Lee, J. Im, I. Chang, G. Cho","doi":"10.12989/GAE.2021.25.1.031","DOIUrl":"https://doi.org/10.12989/GAE.2021.25.1.031","url":null,"abstract":"Injection grouting is one of the most common ground improvement practice to increase the strength and reduce the hydraulic conductivity of soils. Owing to the environmental concerns of conventional grout materials, such as cement-based or silicate-based materials, bio-inspired biogeotechnical approaches are considered to be new sustainable and environmentally friendly ground improvement methods. Biopolymers, which are excretory products from living organisms, have been shown to significantly reduce the hydraulic conductivity via pore-clogging and increase the strength of soils. To study the practical application of biopolymers for seepage and ground water control, in this study, we explored the injection capabilities of biopolymer-based grout materials in both linear aperture and particulate media (i.e., sand and glassbeads) considering different injection pressures, biopolymer concentrations, and flow channel geometries. The hydraulic conductivity control of a biopolymer-based grout material was evaluated after injection into sandy soil under confined boundary conditions. The results showed that the performance of xanthan gum injection was mainly affected by the injection pressure and pore geometry (e.g., porosity) inside the soil. Additionally, with an increase in the xanthan gum concentration, the injection efficiency diminished while the hydraulic conductivity reduction efficiency enhanced significantly. The results of this study provide the potential capabilities of injection grouting to be performed with biopolymer-based materials for field application.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":"25 1","pages":"31"},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66475581","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.2021.25.3.221
D. Chang, M. H. Hung, Sangseom Jeong
A two dimensional model of linearly elastic soil spring used for the settlement analysis of the flexible mat foundation is suggested in this study. The spring constants of the soils underneath the foundation were modeled assuming uniformly vertical load applied onto the foundation. The soil spring constants were back calculated using the three-dimensional finite element analysis with Midas GTS NX program. Variation of the soil spring constants was modeled as a two-dimensional polynomial function in terms of the normalized spatial distances between the center of foundation and the analytical points. The Lysmer's analog spring for soils underneath the rigid foundation was adopted and calibrated for the flexible foundation. For validations, the newly proposed soil spring model was incorporated into a two dimensional finite difference analysis for a square mat foundation at the surface of an elastic half-space consisting of soft clays. Comparative study was made for elastic soils where the shear wave velocity is 120~180 m/s and the Poisson's ratio varies at 0.3~0.5. The resulting foundation settlements from the two dimensional finite difference analysis with the proposed soil springs were found in good agreement with those obtained directly from three dimensional finite element analyses. Details of the applications and limitations of the modified Lysmer's analog springs were discussed in this study.
{"title":"Modified lysmer’s analog model for two dimensional mat settlements under vertically uniform load","authors":"D. Chang, M. H. Hung, Sangseom Jeong","doi":"10.12989/GAE.2021.25.3.221","DOIUrl":"https://doi.org/10.12989/GAE.2021.25.3.221","url":null,"abstract":"A two dimensional model of linearly elastic soil spring used for the settlement analysis of the flexible mat foundation is suggested in this study. The spring constants of the soils underneath the foundation were modeled assuming uniformly vertical load applied onto the foundation. The soil spring constants were back calculated using the three-dimensional finite element analysis with Midas GTS NX program. Variation of the soil spring constants was modeled as a two-dimensional polynomial function in terms of the normalized spatial distances between the center of foundation and the analytical points. The Lysmer's analog spring for soils underneath the rigid foundation was adopted and calibrated for the flexible foundation. For validations, the newly proposed soil spring model was incorporated into a two dimensional finite difference analysis for a square mat foundation at the surface of an elastic half-space consisting of soft clays. Comparative study was made for elastic soils where the shear wave velocity is 120~180 m/s and the Poisson's ratio varies at 0.3~0.5. The resulting foundation settlements from the two dimensional finite difference analysis with the proposed soil springs were found in good agreement with those obtained directly from three dimensional finite element analyses. Details of the applications and limitations of the modified Lysmer's analog springs were discussed in this study.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":"25 1","pages":"221-231"},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66476168","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.2021.25.5.373
Mahdy Khari, Ali Dehghanbandaki, D. J. Armaghani
{"title":"Physical modelling of bending moments in single piles under combined loads in layered soil","authors":"Mahdy Khari, Ali Dehghanbandaki, D. J. Armaghani","doi":"10.12989/GAE.2021.25.5.373","DOIUrl":"https://doi.org/10.12989/GAE.2021.25.5.373","url":null,"abstract":"","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":"25 1","pages":"373-381"},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66476615","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.2021.25.6.455
V. Sarfarazi, Kaveh Asgari, M. Nasrollahi
The objective of this study is investigating the effect of loading rates on the interaction between rock bolts and rock bridges using experimental test and numerical simulation. A new test set up was developed experimentally for determination of tensile strength of bridge area. A concrete block with dimensions of 15 x 15 x 10 cm consisting non-persistent notch was prepared and subjected to tensile loading using special loading set up. The configuration of non-persistent joint was different in various samples. A 30-ton hydraulic load cell applied tensile loading to concrete complex with a high-pressure rate of 0.01 mm per second. Simultaneously with experimental test, numerical simulation was performed on the tensile behavior of non-persistent joint adjacent to rock bolt. Two sets of non-persistent joint were prepared. The first sets were similar to experimental one while, in the second sets, two edge joints with lengths of 1.5 cm, 3 cm and 4.5 cm were prepared. The angle of these joint related to horizontal axis were 0, 15, 30, 45, 60, 75, and 90. Also, the rock bolts adjacent to joints were simulated and were subjected to tensile loading with two high and low loading rates i.e. 0.01 mm/sec and 0.0001 mm/sec. The results showed that the crack propagation angle related to tensile load direction was decreased by decreasing the tensile loading rate. The tensile failure stress decreased by presence of pre-existing crack within the model. Tensile failure stress had minimum value whenever the angle of pre-existing crack was 0o. The numerical results were in a good accordance with experimental ones.
本研究的目的是通过试验试验和数值模拟来研究加载速率对岩石锚杆与岩石桥梁相互作用的影响。研制了一种新型的桥梁区域抗拉强度试验装置。制备了尺寸为15 x 15 x 10 cm的混凝土块，其中包含非持久缺口，并使用特殊加载装置进行拉伸加载。不同试样的非持久接头形态不同。一个30吨的液压测压元件以每秒0.01毫米的高压速率对混凝土复合体施加拉伸载荷。在进行试验试验的同时，对锚杆相邻非持久节理的抗拉特性进行了数值模拟。制备两组非持续性关节。第一组与实验组相似，第二组分别制备长度为1.5 cm、3 cm和4.5 cm的两个边缘接头。这些关节与水平轴的夹角分别为0、15、30、45、60、75和90。模拟节理附近的锚杆，分别以0.01 mm/sec和0.0001 mm/sec两种高、低加载速率进行拉伸加载。结果表明:随着拉伸加载速率的降低，与拉伸加载方向相关的裂纹扩展角减小;由于模型中存在预先存在的裂纹，拉伸破坏应力减小。当预存裂纹角度为0时，拉伸破坏应力最小。数值计算结果与实验结果吻合较好。
{"title":"Interaction between rock bolt and rock bridge under tensile loading","authors":"V. Sarfarazi, Kaveh Asgari, M. Nasrollahi","doi":"10.12989/GAE.2021.25.6.455","DOIUrl":"https://doi.org/10.12989/GAE.2021.25.6.455","url":null,"abstract":"The objective of this study is investigating the effect of loading rates on the interaction between rock bolts and rock bridges using experimental test and numerical simulation. A new test set up was developed experimentally for determination of tensile strength of bridge area. A concrete block with dimensions of 15 x 15 x 10 cm consisting non-persistent notch was prepared and subjected to tensile loading using special loading set up. The configuration of non-persistent joint was different in various samples. A 30-ton hydraulic load cell applied tensile loading to concrete complex with a high-pressure rate of 0.01 mm per second. Simultaneously with experimental test, numerical simulation was performed on the tensile behavior of non-persistent joint adjacent to rock bolt. Two sets of non-persistent joint were prepared. The first sets were similar to experimental one while, in the second sets, two edge joints with lengths of 1.5 cm, 3 cm and 4.5 cm were prepared. The angle of these joint related to horizontal axis were 0, 15, 30, 45, 60, 75, and 90. Also, the rock bolts adjacent to joints were simulated and were subjected to tensile loading with two high and low loading rates i.e. 0.01 mm/sec and 0.0001 mm/sec. The results showed that the crack propagation angle related to tensile load direction was decreased by decreasing the tensile loading rate. The tensile failure stress decreased by presence of pre-existing crack within the model. Tensile failure stress had minimum value whenever the angle of pre-existing crack was 0o. The numerical results were in a good accordance with experimental ones.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":"25 1","pages":"455"},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66476985","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.2021.26.2.101
Susheel Kumar, E. Sujatha
Soil stabilization is widely used to favourably amend the soil behaviour. The use of biopolymers to treat soil is not only an eco-friendly but is also a sustainable approach. Biopolymers, xanthan gum and guar gum are used to augment the strength of clayey sand. Xanthan gum is anionic while guar gum is non-ionic. Triaxial tests were conducted on treated soil samples to understand the effect of biopolymer treatment on clayey sand at different dosages and curing periods. Shear strength parameters –angle of internal friction and cohesion increases appreciably on treating soil with xanthan and guar gum for all dosages investigated, though angle of internal friction decreases with the curing period in case of xanthan gum treated soil. Xanthan gum performs better in enhancing the strength and deformation behaviour of the soil compared to guar gum. There is a substantial gain in early strength but as the curing period increases further, the rate of increase in strength is marginal. The deformation modulus at failure also increases with the biopolymer content. The reduction in post-peak strength of treated soil is sudden and drastic indicating brittle behavior. The energy absorption capacity of the biopolymer treated soil increases with increase in biopolymer content and curing period. The strength gain in soil can be ascribed to the formation of hydrogels that are cementitious in nature. Strength is also improved through the ionic / hydrogen bonds that are formed by biopolymer addition.
{"title":"Experimental investigation on the shear strength and deformation behaviour of xanthan gum and guar gum treated clayey sand","authors":"Susheel Kumar, E. Sujatha","doi":"10.12989/GAE.2021.26.2.101","DOIUrl":"https://doi.org/10.12989/GAE.2021.26.2.101","url":null,"abstract":"Soil stabilization is widely used to favourably amend the soil behaviour. The use of biopolymers to treat soil is not only an eco-friendly but is also a sustainable approach. Biopolymers, xanthan gum and guar gum are used to augment the strength of clayey sand. Xanthan gum is anionic while guar gum is non-ionic. Triaxial tests were conducted on treated soil samples to understand the effect of biopolymer treatment on clayey sand at different dosages and curing periods. Shear strength parameters –angle of internal friction and cohesion increases appreciably on treating soil with xanthan and guar gum for all dosages investigated, though angle of internal friction decreases with the curing period in case of xanthan gum treated soil. Xanthan gum performs better in enhancing the strength and deformation behaviour of the soil compared to guar gum. There is a substantial gain in early strength but as the curing period increases further, the rate of increase in strength is marginal. The deformation modulus at failure also increases with the biopolymer content. The reduction in post-peak strength of treated soil is sudden and drastic indicating brittle behavior. The energy absorption capacity of the biopolymer treated soil increases with increase in biopolymer content and curing period. The strength gain in soil can be ascribed to the formation of hydrogels that are cementitious in nature. Strength is also improved through the ionic / hydrogen bonds that are formed by biopolymer addition.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":"26 1","pages":"101"},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66477665","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.2021.26.5.465
Omer Faruk Ugurlu, C. Ozturk
In the mining industry, significant progress and increased mineral production cause waste disposal issues which is one of the crucial problems in mining operations. It leads to both environmental and economic issues. Particularly, wastes from the production of metallic sulfide ore cause serious environmental pollution. In the last three decades, waste has been stored in underground openings in a controlled manner as paste-fill. Paste-fill is created by waste, water, and chemical additives. In this paper, two types of wastes were chosen to investigate the usability of tailings as paste-fill material. A lead and zinc underground mine was selected as a research site located in Balikesir, Turkey. First of all, several tests were conducted to analyze the physical, chemical, and mineralogical characteristics of paste-fill materials. Then, one of the design of experiment methods was used to create different mixtures of paste-fill specimens by changing the binder ratio and water content as input variables for four curing times. Finally, the strength properties were obtained as output variables, and an optimum mixture of paste-fill was determined. The results show that the tailings can be used as paste-fill material to achieve environmental and economic benefits and provide a safe working environment.
{"title":"Experimental investigation for the use of tailings as paste-fill material through design of experiment","authors":"Omer Faruk Ugurlu, C. Ozturk","doi":"10.12989/GAE.2021.26.5.465","DOIUrl":"https://doi.org/10.12989/GAE.2021.26.5.465","url":null,"abstract":"In the mining industry, significant progress and increased mineral production cause waste disposal issues which is one of the crucial problems in mining operations. It leads to both environmental and economic issues. Particularly, wastes from the production of metallic sulfide ore cause serious environmental pollution. In the last three decades, waste has been stored in underground openings in a controlled manner as paste-fill. Paste-fill is created by waste, water, and chemical additives. In this paper, two types of wastes were chosen to investigate the usability of tailings as paste-fill material. A lead and zinc underground mine was selected as a research site located in Balikesir, Turkey. First of all, several tests were conducted to analyze the physical, chemical, and mineralogical characteristics of paste-fill materials. Then, one of the design of experiment methods was used to create different mixtures of paste-fill specimens by changing the binder ratio and water content as input variables for four curing times. Finally, the strength properties were obtained as output variables, and an optimum mixture of paste-fill was determined. The results show that the tailings can be used as paste-fill material to achieve environmental and economic benefits and provide a safe working environment.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":"26 1","pages":"465"},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66479583","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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