Contamination of soils and groundwater resources has become one of the most serious global environmental problems in recent years. The use of natural and inexpensive adsorbents such as zeolite is one of the appropriate methods to prevent the spread of contaminants and increase the adsorption capacity of the soil. Therefore, in the present study, zeolite is used as an option to improve the soil environmental condition. In this research, the behavior of the mixture of sand with 15% kaolinite clay is investigated at first, in both conditions of non-contaminated and contaminated with lead nitrate. Due to the limited adsorption capacity of the sand containing kaolinite, different percentages of zeolite adsorbent (as 5, 10, and 15 percent of soil weight) were added to this mixture to investigate the adsorption capacity and changes in strength parameters of the soil and adsorbent mixture. These parameters were also compared between zeolite and bentonite adsorbents. According to the results of the atomic adsorption test, zeolite has a favorable effect on increasing the adsorption capacity of heavy metals in soils such that by adding 5% zeolite, the amount of lead adsorption capacity increases by about 70%. Followed by investigating the static behavior and adsorption capacity of different compounds of soil containing adsorbent and without adsorbent, the dynamic behavior of these compounds in both conditions of non-contaminated and contaminated with lead nitrate was studied. The results show that in both contaminated and uncontaminated conditions, the initial shear modulus decreases with increasing zeolite content adsorbent. Also, dynamic behavior shows that in the combination of soil with both types of adsorbents, by increasing the concentration of heavy metal, the cycles corresponding to Ru decreases.
{"title":"Investigating the zeolite and bentonite adsorbent effect on the static, dynamic, and environmental parameters of soil","authors":"M. H. Zade, Mahmuod Hassanlourad, S. .. Naeini","doi":"10.1680/jgrim.21.00061","DOIUrl":"https://doi.org/10.1680/jgrim.21.00061","url":null,"abstract":"Contamination of soils and groundwater resources has become one of the most serious global environmental problems in recent years. The use of natural and inexpensive adsorbents such as zeolite is one of the appropriate methods to prevent the spread of contaminants and increase the adsorption capacity of the soil. Therefore, in the present study, zeolite is used as an option to improve the soil environmental condition. In this research, the behavior of the mixture of sand with 15% kaolinite clay is investigated at first, in both conditions of non-contaminated and contaminated with lead nitrate. Due to the limited adsorption capacity of the sand containing kaolinite, different percentages of zeolite adsorbent (as 5, 10, and 15 percent of soil weight) were added to this mixture to investigate the adsorption capacity and changes in strength parameters of the soil and adsorbent mixture. These parameters were also compared between zeolite and bentonite adsorbents. According to the results of the atomic adsorption test, zeolite has a favorable effect on increasing the adsorption capacity of heavy metals in soils such that by adding 5% zeolite, the amount of lead adsorption capacity increases by about 70%. Followed by investigating the static behavior and adsorption capacity of different compounds of soil containing adsorbent and without adsorbent, the dynamic behavior of these compounds in both conditions of non-contaminated and contaminated with lead nitrate was studied. The results show that in both contaminated and uncontaminated conditions, the initial shear modulus decreases with increasing zeolite content adsorbent. Also, dynamic behavior shows that in the combination of soil with both types of adsorbents, by increasing the concentration of heavy metal, the cycles corresponding to Ru decreases.","PeriodicalId":51705,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Ground Improvement","volume":"126 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75823921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Sakr, Wasiem R. Azzam, M. Meguid, Asaad F. Hassan, Hebatalla Ghoneim
Expansive soils are generally characterized by their volume change when subjected to variation in water content. This may result in significant damage to supported and nearby structures. In this study, the swelling properties of bentonite material as an expansive soil are first determined. The expansive soil is then improved using two different approaches, namely, micro-metakaolin and ferric chloride solution. The optimum percentage for both additives are determined using laboratory experiments. These percentages are found to be 25% and 1% for the micro-metakaolin and the ferric chloride solution, respectively. The free swell index of the bentonite after being treated with micro-metakaolin and ferric chloride solution at the optimum percentages are found to decrease by about 54% and 62%, respectively. Meanwhile, the swelling pressure for the expansive soil decreased by 33% and 43% when mixed with the same optimum values of micro-metakaolin and ferric chloride solution, respectively. Based on the results obtained in this study, the addition of ferric chloride solution achieved better results compared to micro-metakaolin. This improvement technique may be used to enhance the properties of expansive soils that support different construction engineering projects.
{"title":"Comparative Evaluation of Micro-Metakaolin and Ferric Chloride Solution in Stabilizing Expansive Soils","authors":"M. Sakr, Wasiem R. Azzam, M. Meguid, Asaad F. Hassan, Hebatalla Ghoneim","doi":"10.1680/jgrim.21.00015","DOIUrl":"https://doi.org/10.1680/jgrim.21.00015","url":null,"abstract":"Expansive soils are generally characterized by their volume change when subjected to variation in water content. This may result in significant damage to supported and nearby structures. In this study, the swelling properties of bentonite material as an expansive soil are first determined. The expansive soil is then improved using two different approaches, namely, micro-metakaolin and ferric chloride solution. The optimum percentage for both additives are determined using laboratory experiments. These percentages are found to be 25% and 1% for the micro-metakaolin and the ferric chloride solution, respectively. The free swell index of the bentonite after being treated with micro-metakaolin and ferric chloride solution at the optimum percentages are found to decrease by about 54% and 62%, respectively. Meanwhile, the swelling pressure for the expansive soil decreased by 33% and 43% when mixed with the same optimum values of micro-metakaolin and ferric chloride solution, respectively. Based on the results obtained in this study, the addition of ferric chloride solution achieved better results compared to micro-metakaolin. This improvement technique may be used to enhance the properties of expansive soils that support different construction engineering projects.","PeriodicalId":51705,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Ground Improvement","volume":"36 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82184753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Roth, J. DeJong, Jordan Greer, L. Caslake, Doug Nelson, R. Parales
The controlled production of microbial growth has the potential to reduce groundwater flow in seepage and dewatering systems. Stimulating the growth of indigenous bacteria could clog the pore space and result in a substantial permeability reduction. This study investigated the spatial distribution of permeability reduction under different nutrient stimulation treatments of indigenous bacteria across 16 cm columns of Ottawa 50-70 sand. Spatially uniform permeability reductions of up to an order of magnitude were achieved using both a high glucose (50 mg L−1) and a low glucose (10 mg L−1) nutrient formulation. The overall permeability began to drop by day 2 and generally reached a minimum permeability by day 14. There was no noticeable difference in the final permeability nor the rate of permeability reduction between high and low glucose formulations. Upscaling of experiments is highly recommended for future studies on the spatial uniformity of microbial growth and biologically induced permeability reductions.
微生物生长的控制生产有可能减少渗漏和脱水系统中的地下水流量。刺激原生细菌的生长会堵塞孔隙空间，导致渗透率大幅降低。研究了不同营养刺激处理下土生细菌在渥太华50-70砂16 cm柱上渗透率降低的空间分布。使用高葡萄糖(50 mg L - 1)和低葡萄糖(10 mg L - 1)营养物配方，可实现空间均匀的渗透率降低，最高可达一个数量级。总体渗透率在第2天开始下降，一般在第14天达到最小渗透率。在高糖和低糖制剂之间，最终通透性和通透性降低率没有显著差异。对于微生物生长的空间均匀性和生物诱导的渗透率降低的未来研究，强烈建议扩大实验规模。
{"title":"Stimulated Microbial Growth for Permeability Reductions in Granular Soils","authors":"M. Roth, J. DeJong, Jordan Greer, L. Caslake, Doug Nelson, R. Parales","doi":"10.1680/jgrim.21.00011","DOIUrl":"https://doi.org/10.1680/jgrim.21.00011","url":null,"abstract":"The controlled production of microbial growth has the potential to reduce groundwater flow in seepage and dewatering systems. Stimulating the growth of indigenous bacteria could clog the pore space and result in a substantial permeability reduction. This study investigated the spatial distribution of permeability reduction under different nutrient stimulation treatments of indigenous bacteria across 16 cm columns of Ottawa 50-70 sand. Spatially uniform permeability reductions of up to an order of magnitude were achieved using both a high glucose (50 mg L−1) and a low glucose (10 mg L−1) nutrient formulation. The overall permeability began to drop by day 2 and generally reached a minimum permeability by day 14. There was no noticeable difference in the final permeability nor the rate of permeability reduction between high and low glucose formulations. Upscaling of experiments is highly recommended for future studies on the spatial uniformity of microbial growth and biologically induced permeability reductions.","PeriodicalId":51705,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Ground Improvement","volume":"26 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84893224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The adjusted porosity/cement index η/(Civ)a has been showing its usefulness in modelling the strength and stiffness of a variety of artificially cemented soils as it encompasses into a single parameter both the influences of the compactness and of the cement content. That being so, it is theoretically possible to obtain the same mechanical response by establishing a specific η/(Civ)a value, which could be attained by several combinations of porosities and cement contents. Yet, this has not been verified over a wide spectrum of different dosages molded at the same η/(Civ)a value, especially for stiffness data. As a reason, present study addresses this issue by assessing the initial shear modulus and the unconfined compression of different dosages of an artificially cemented soil considering seven η/(Civ)avalues. A minimum of three mix designs were molded within each η/(Civ)a and five specimens were tested for each dosage. Both the stiffness and the strength results were evaluated through Tukey's multiple comparisons tests aiming to check for statistical equivalence of the obtained results within the same η/(Civ)a value. The tests results have revealed statistical differences amongst some dosages assembled with the same adjusted porosity/cement index value. Yet, both the stiffness and the strength outcomes were properly correlated to the η/(Civ)a index, yielding power-type relationships presenting great coefficients of determination.
{"title":"Mechanical Response of a Cemented Soil over a Wide Range of Porosities and Cement Contents","authors":"Hugo Carlos Scheuermann Filho, N. Consoli","doi":"10.1680/jgrim.22.00028","DOIUrl":"https://doi.org/10.1680/jgrim.22.00028","url":null,"abstract":"The adjusted porosity/cement index η/(Civ)a has been showing its usefulness in modelling the strength and stiffness of a variety of artificially cemented soils as it encompasses into a single parameter both the influences of the compactness and of the cement content. That being so, it is theoretically possible to obtain the same mechanical response by establishing a specific η/(Civ)a value, which could be attained by several combinations of porosities and cement contents. Yet, this has not been verified over a wide spectrum of different dosages molded at the same η/(Civ)a value, especially for stiffness data. As a reason, present study addresses this issue by assessing the initial shear modulus and the unconfined compression of different dosages of an artificially cemented soil considering seven η/(Civ)avalues. A minimum of three mix designs were molded within each η/(Civ)a and five specimens were tested for each dosage. Both the stiffness and the strength results were evaluated through Tukey's multiple comparisons tests aiming to check for statistical equivalence of the obtained results within the same η/(Civ)a value. The tests results have revealed statistical differences amongst some dosages assembled with the same adjusted porosity/cement index value. Yet, both the stiffness and the strength outcomes were properly correlated to the η/(Civ)a index, yielding power-type relationships presenting great coefficients of determination.","PeriodicalId":51705,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Ground Improvement","volume":"17 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74961087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The paper investigates the effect of hydrated lime on shear strength properties and behaviour of London clay, a soil extensively encountered in construction in the London area and the South Eastern England. Unconsolidated Undrained (UU) tests were performed to identify the effect of lime dosage, compaction water content and curing time on the shear strength and stress-strain behaviour of the treated soil. The mineralogical and physicochemical transformations occurring during the curing stage of the soil were also monitored to support the interpretation of the triaxial testing results and verify hypotheses made on the evolution of the chemical reactions and the development of cementation bonds. The results showed that strengths gain was strongly influenced by lime content and the curing period, whereas the compaction water content was less influential. An interesting finding of practical relevance is that the strength evolution is likely to continue over long periods of time and result in very considerable strength gains upon the hardening of pozzolanic reaction products. At the same time, adequate early strength gains and adequate soil treatment can be obtained with reduced use of material consumption, thus further increasing the sustainability of the treatment processes. The paper has also highlighted the importance for engineering design of considering the brittle stress-strain response of the lime treated soil, and the benefit of using lower amounts of lime to alleviate this undesirable effect. The implications of various aspects of soil brittleness in different situations merit further attention and should be explored via modelling in future work.
{"title":"An investigation of the strength evolution of lime-treated London clay soil","authors":"Zoheir Kichou, M. Mavroulidou, M. Gunn","doi":"10.1680/jgrim.21.00053","DOIUrl":"https://doi.org/10.1680/jgrim.21.00053","url":null,"abstract":"The paper investigates the effect of hydrated lime on shear strength properties and behaviour of London clay, a soil extensively encountered in construction in the London area and the South Eastern England. Unconsolidated Undrained (UU) tests were performed to identify the effect of lime dosage, compaction water content and curing time on the shear strength and stress-strain behaviour of the treated soil. The mineralogical and physicochemical transformations occurring during the curing stage of the soil were also monitored to support the interpretation of the triaxial testing results and verify hypotheses made on the evolution of the chemical reactions and the development of cementation bonds. The results showed that strengths gain was strongly influenced by lime content and the curing period, whereas the compaction water content was less influential. An interesting finding of practical relevance is that the strength evolution is likely to continue over long periods of time and result in very considerable strength gains upon the hardening of pozzolanic reaction products. At the same time, adequate early strength gains and adequate soil treatment can be obtained with reduced use of material consumption, thus further increasing the sustainability of the treatment processes. The paper has also highlighted the importance for engineering design of considering the brittle stress-strain response of the lime treated soil, and the benefit of using lower amounts of lime to alleviate this undesirable effect. The implications of various aspects of soil brittleness in different situations merit further attention and should be explored via modelling in future work.","PeriodicalId":51705,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Ground Improvement","volume":"5 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82382768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Ritter, P. Paniagua, Caroline Berge Hansen, G. Cornelissen
Carbon-intensive binders such as cement are traditionally employed to stabilise peat. Few studies have investigated alternative materials such as biochar to improve peat stability while simultaneously sequestering carbon dioxide (CO2). This study explored biochar produced through pyrolysis of clean wood and leaves to stabilize peat from Tiller-Flotten, Norway. Unconfined compressive strength (UCS), water content and pH measurements on biochar, Portland composite cement (CEM II) and peat compositions and a sustainability assessment were conducted. It was found that biochar amendment increased strength and stiffness of peat and cement-stabilised peat. Biochar showed the potential to reduce the cement amount when stabilising peat while retaining geotechnical properties. Peat stabilised with 200 kg/m3 of biochar and 100 kg/m3 of cement exhibited comparable strength (63.3±4.2 kPa, n = 3) as samples with 200 kg/m3 of cement (63.2±1.3 kPa, n = 3), but with a negative carbon footprint. Adding biochar quantities greater than 27% of the cement quantities resulted in a climate-neutral stabilisation. At a carbon price of approximately 85 €/tonne, the biochar costs equalled the cement costs. The cement-only samples outperformed the ones with additional biochar in terms of shear strength/€, while future carbon prices increased the competitiveness of biochar amendments.
传统上使用水泥等碳密集型粘合剂来稳定泥炭。很少有研究调查替代材料，如生物炭，以提高泥炭的稳定性，同时隔离二氧化碳(CO2)。本研究探索了通过热解干净的木材和树叶来稳定来自挪威蒂勒-弗洛滕的泥炭而产生的生物炭。对生物炭、波特兰复合水泥(CEM II)和泥炭组分的无侧限抗压强度(UCS)、含水量和pH值进行了测量，并进行了可持续性评估。研究发现，生物炭改性提高了泥炭和水泥稳定泥炭的强度和刚度。在稳定泥炭的同时，生物炭显示出减少水泥用量的潜力，同时保持了土工性能。用200 kg/m3的生物炭和100 kg/m3的水泥稳定泥炭的强度(63.3±4.2 kPa, n = 3)与用200 kg/m3的水泥(63.2±1.3 kPa, n = 3)稳定泥炭的强度相当，但碳足迹为负。添加的生物炭量大于水泥量的27%，可以实现气候中性的稳定。在碳价格约为每吨85欧元的情况下，生物炭的成本与水泥的成本相当。仅水泥的样品在抗剪强度/€方面优于添加生物炭的样品，而未来的碳价格增加了生物炭改性剂的竞争力。
{"title":"Biochar amendment for improved and more sustainable peat stabilisation","authors":"S. Ritter, P. Paniagua, Caroline Berge Hansen, G. Cornelissen","doi":"10.1680/jgrim.22.00023","DOIUrl":"https://doi.org/10.1680/jgrim.22.00023","url":null,"abstract":"Carbon-intensive binders such as cement are traditionally employed to stabilise peat. Few studies have investigated alternative materials such as biochar to improve peat stability while simultaneously sequestering carbon dioxide (CO2). This study explored biochar produced through pyrolysis of clean wood and leaves to stabilize peat from Tiller-Flotten, Norway. Unconfined compressive strength (UCS), water content and pH measurements on biochar, Portland composite cement (CEM II) and peat compositions and a sustainability assessment were conducted. It was found that biochar amendment increased strength and stiffness of peat and cement-stabilised peat. Biochar showed the potential to reduce the cement amount when stabilising peat while retaining geotechnical properties. Peat stabilised with 200 kg/m3 of biochar and 100 kg/m3 of cement exhibited comparable strength (63.3±4.2 kPa, n = 3) as samples with 200 kg/m3 of cement (63.2±1.3 kPa, n = 3), but with a negative carbon footprint. Adding biochar quantities greater than 27% of the cement quantities resulted in a climate-neutral stabilisation. At a carbon price of approximately 85 €/tonne, the biochar costs equalled the cement costs. The cement-only samples outperformed the ones with additional biochar in terms of shear strength/€, while future carbon prices increased the competitiveness of biochar amendments.","PeriodicalId":51705,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Ground Improvement","volume":"13 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86472962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rubén Alejandro Quiñónez Samaniego, G. Bruschi, H. C. Scheuermann Filho, Mariana Tonini de Araújo, L. Festugato, N. Consoli
Troublesome events are related to the stabilization of sulfate-rich soils with calcium-based materials. To overcome these inconveniences, researches have been conducted applying modified and alternative treatments to soils containing low and high sulfate levels. This paper intends to assess the effects of mellowing period (2 and 4 days), Portland cement content (5%, 7% and 9%), density (15.75kN.m−3, 16.60kN.m−3, and 17.50kN.m−3) and curing time (14 and 28 days) on the performance of a clayey soil from the Paraguayan Chaco region containing high amounts of sulfates. A complete factorial design set was carried out to assess the unconfined compressive strength and the one-dimensional free vertical swelling of compacted soil-cement-lime mixtures. Results showed a positive effect of the mellowing period relative to the swelling of the stabilized soil. In addition, the curing period, the amount of cement and the dry unit weight were the most influential factors regarding the unconfined compressive strength. The stabilization method addressed in this research, i.e., extended mellowing combined with lime and Portland cement, seems to be of great importance for practical purposes on the stabilization of soils containing high amounts of sulfates.
{"title":"Effect of extended mellowing on strength and swelling behavior of a high sulfated soil","authors":"Rubén Alejandro Quiñónez Samaniego, G. Bruschi, H. C. Scheuermann Filho, Mariana Tonini de Araújo, L. Festugato, N. Consoli","doi":"10.1680/jgrim.22.00017","DOIUrl":"https://doi.org/10.1680/jgrim.22.00017","url":null,"abstract":"Troublesome events are related to the stabilization of sulfate-rich soils with calcium-based materials. To overcome these inconveniences, researches have been conducted applying modified and alternative treatments to soils containing low and high sulfate levels. This paper intends to assess the effects of mellowing period (2 and 4 days), Portland cement content (5%, 7% and 9%), density (15.75kN.m−3, 16.60kN.m−3, and 17.50kN.m−3) and curing time (14 and 28 days) on the performance of a clayey soil from the Paraguayan Chaco region containing high amounts of sulfates. A complete factorial design set was carried out to assess the unconfined compressive strength and the one-dimensional free vertical swelling of compacted soil-cement-lime mixtures. Results showed a positive effect of the mellowing period relative to the swelling of the stabilized soil. In addition, the curing period, the amount of cement and the dry unit weight were the most influential factors regarding the unconfined compressive strength. The stabilization method addressed in this research, i.e., extended mellowing combined with lime and Portland cement, seems to be of great importance for practical purposes on the stabilization of soils containing high amounts of sulfates.","PeriodicalId":51705,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Ground Improvement","volume":"60 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76937446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study investigated the effects of three improvement methods, the umbrella arch method (UAM), soil nailing and micropiling, on the performance of a New Austrian Tunneling Method (NATM) tunnel in Tehran, Iran. This tunnel passes under Modares freeway, a major artery in Tehran and is part of the Arash Project. The construction of a tunnel with a large, approximately square cross-section on a disturbed soil stratum and the existence of adjacent embedded canals (qanat) have made Modares tunnel one of the most challenging parts of this project. These challenges required the use of a nearly square two-story tunnel. This uncommon square shape was chosen because of limitations caused by adjacent facilities. All combinations of three supporting systems (forepoling UAM, soil nailing and micropiling) were investigated using the numerical method. The influence of these methods on surface settlement and the adequacy of the initial tunnel lining are discussed. In short, Forepoling was the most effective with a 24% decrease in settlement compared to Initial model. Combining the forepoling and nailing systems decreased settlement 37.5% and was the most effective synchronic system. The best results were for the model incorporating all supporting systems, which was a decrease in settlement of 47.5%.
{"title":"Effects of forepoling, soil nailing and micropiling on the behavior of a two-story tunnel","authors":"S. Majidian, B. Alinejad, A. Golshani","doi":"10.1680/jgrim.19.00093","DOIUrl":"https://doi.org/10.1680/jgrim.19.00093","url":null,"abstract":"This study investigated the effects of three improvement methods, the umbrella arch method (UAM), soil nailing and micropiling, on the performance of a New Austrian Tunneling Method (NATM) tunnel in Tehran, Iran. This tunnel passes under Modares freeway, a major artery in Tehran and is part of the Arash Project. The construction of a tunnel with a large, approximately square cross-section on a disturbed soil stratum and the existence of adjacent embedded canals (qanat) have made Modares tunnel one of the most challenging parts of this project. These challenges required the use of a nearly square two-story tunnel. This uncommon square shape was chosen because of limitations caused by adjacent facilities. All combinations of three supporting systems (forepoling UAM, soil nailing and micropiling) were investigated using the numerical method. The influence of these methods on surface settlement and the adequacy of the initial tunnel lining are discussed. In short, Forepoling was the most effective with a 24% decrease in settlement compared to Initial model. Combining the forepoling and nailing systems decreased settlement 37.5% and was the most effective synchronic system. The best results were for the model incorporating all supporting systems, which was a decrease in settlement of 47.5%.","PeriodicalId":51705,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Ground Improvement","volume":"76 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86596943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Luci Queiroz, Lucas Luciano Sousa Batista, Laura Mendonça Ponte Souza, Max Deluan Lima, Sarah Danieli, G. Bruschi, C. Bergmann
This study investigated the utilization of an alkali-activated system to stabilize a granular soil. For the alkali-activated binder, rice husk ash was used as the precursor and carbide lime as the activator. An experimental program was carried out to analyze the strength and stiffness of sand-rice husk ash-carbide lime mixtures. Different binder contents (10 and 20%), dry densities (15.5, 16.5 and 17.5kN/m³), curing periods (7 and 28 days) and Ca/SiO2 ratios (1, 1.5 and 2) were evaluated. In addition, microstructural analyses were conducted on the mixed materials. The increase in binder content, dry density, and curing period led to the improvement of strength and stiffness, while the increase in Ca/SiO2 ratio hindered the mechanical behavior. The statistical analysis revealed that all studied factors influenced the mechanical behavior of soil-binder mixtures. In addition, the condition to obtain the highest strength and stiffness was evidenced in the combination of higher dry unit weight, binder content, curing period, and lower molar ratio. The alkali-activated system was shown to be a promising binder agent for soil stabilization for both strength and stiffness. Finally, two calcium aluminosilicate hydrate structures were identified in the soil-binder mixtures, soulunite and jaffeite, indicating ideal structures for the composition of cement hydrates.
{"title":"Alkali-activated system of carbide lime and rice husk for granular soil stabilization","authors":"Luci Queiroz, Lucas Luciano Sousa Batista, Laura Mendonça Ponte Souza, Max Deluan Lima, Sarah Danieli, G. Bruschi, C. Bergmann","doi":"10.1680/jgrim.21.00048","DOIUrl":"https://doi.org/10.1680/jgrim.21.00048","url":null,"abstract":"This study investigated the utilization of an alkali-activated system to stabilize a granular soil. For the alkali-activated binder, rice husk ash was used as the precursor and carbide lime as the activator. An experimental program was carried out to analyze the strength and stiffness of sand-rice husk ash-carbide lime mixtures. Different binder contents (10 and 20%), dry densities (15.5, 16.5 and 17.5kN/m³), curing periods (7 and 28 days) and Ca/SiO2 ratios (1, 1.5 and 2) were evaluated. In addition, microstructural analyses were conducted on the mixed materials. The increase in binder content, dry density, and curing period led to the improvement of strength and stiffness, while the increase in Ca/SiO2 ratio hindered the mechanical behavior. The statistical analysis revealed that all studied factors influenced the mechanical behavior of soil-binder mixtures. In addition, the condition to obtain the highest strength and stiffness was evidenced in the combination of higher dry unit weight, binder content, curing period, and lower molar ratio. The alkali-activated system was shown to be a promising binder agent for soil stabilization for both strength and stiffness. Finally, two calcium aluminosilicate hydrate structures were identified in the soil-binder mixtures, soulunite and jaffeite, indicating ideal structures for the composition of cement hydrates.","PeriodicalId":51705,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Ground Improvement","volume":"47 12","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72443327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Chowdepalli, B. K. Karnamprabhakara, B. Umashankar
Different waste materials, such as fly ash and bottom ash, slag waste, and construction & demolition waste, have been extensively studied to replace depleting natural granular materials for fill applications. Waste foundry sand (WFS), a by-product from the aluminum metal casting industry, is one such waste material that can be a viable fill material. In the present study, extensive large-scale model experimental studies were performed on geogrid-reinforced WFS beds to understand their load-settlement behavior. Basic characterization studies on WFS included gradation, specific gravity, morphology, chemical composition, and compaction testing. During large-scale model experimental (LSME) testing, the geogrid reinforcement was placed at the optimum placement depth, and the maximum improvement in the load-carrying capacity of the footing resting on the reinforced WFS layer was quantified in terms of bearing capacity ratio. The bearing capacity ratio of reinforced WFS beds was found to range between 1.3 and 2.0 based on the test conditions considered in the study. The reduction in settlement of footing on reinforced WFS bed was also quantified. Additionally, the environmental impact of using WFS in reinforced foundation beds was assessed through leachate tests. The dissolved metal concentrations from leachate studies were found to be within permissible limits.
不同的废物，如粉煤灰和底灰、矿渣废物、建筑和拆除垃圾，已经被广泛研究，以取代耗尽的天然颗粒材料的填充应用。废铸造砂(WFS)是铝金属铸造工业的副产品，是一种可以作为可行填充材料的废料。在本研究中，对土工格栅加筋WFS床进行了广泛的大尺度模型试验研究，以了解其荷载沉降行为。WFS的基本表征研究包括级配、比重、形貌、化学成分和压实测试。在大尺度模型试验(large- model experimental, LSME)试验中，将土工格栅加固置于最佳布设深度，以承载力比量化加固后WFS层基础承载能力的最大提升。根据本研究考虑的试验条件，发现加固WFS床的承载力比在1.3 ~ 2.0之间。此外，还量化了加固WFS地基基础沉降的减少。此外，通过渗滤液试验评估了在加固基础床中使用WFS的环境影响。研究发现，渗滤液中溶解的金属浓度在允许范围内。
{"title":"Mechanical and environmental characteristics of geogrid-reinforced waste foundry sand beds","authors":"B. Chowdepalli, B. K. Karnamprabhakara, B. Umashankar","doi":"10.1680/jgrim.21.00022","DOIUrl":"https://doi.org/10.1680/jgrim.21.00022","url":null,"abstract":"Different waste materials, such as fly ash and bottom ash, slag waste, and construction & demolition waste, have been extensively studied to replace depleting natural granular materials for fill applications. Waste foundry sand (WFS), a by-product from the aluminum metal casting industry, is one such waste material that can be a viable fill material. In the present study, extensive large-scale model experimental studies were performed on geogrid-reinforced WFS beds to understand their load-settlement behavior. Basic characterization studies on WFS included gradation, specific gravity, morphology, chemical composition, and compaction testing. During large-scale model experimental (LSME) testing, the geogrid reinforcement was placed at the optimum placement depth, and the maximum improvement in the load-carrying capacity of the footing resting on the reinforced WFS layer was quantified in terms of bearing capacity ratio. The bearing capacity ratio of reinforced WFS beds was found to range between 1.3 and 2.0 based on the test conditions considered in the study. The reduction in settlement of footing on reinforced WFS bed was also quantified. Additionally, the environmental impact of using WFS in reinforced foundation beds was assessed through leachate tests. The dissolved metal concentrations from leachate studies were found to be within permissible limits.","PeriodicalId":51705,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Ground Improvement","volume":"51 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90735890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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