C. Silvani, J. Guedes, Jucimara Silva, Eduardo Tenório, Renan Nascimento
This research shows that brackish water increases the unconfined compressive strength of swelling soil/sugarcane bagasse ash (SCBA)/lime blends. Therefore, brackish water may substitute tap water in soil stabilization. Sodium chloride (NaCl) has been used in lime-ashes-soil treatments. In northeast Brazil, swelling soils are usual and artesian wells sometimes provide brackish water containing NaCl. Northeast Brazil also has a strong sugar and ethanol industry producing sugarcane bagasse ash (SCBA) as a byproduct. Therefore, brackish water can be used in soil-SCBA-lime stabilization. Hence, this work aims to evaluate the use of brackish water as a substitute for tap water in swelling soil- SCBA-lime blends stabilization. Two series of unconfined compression tests were carried out: one with tap water and the other with brackish water. In each group, the lime content varied from 4% to 8%, and the dry density from 13 kN/m3 to 15 kN/m3. All tests were carried out with a swelling soil-SCBA proportion of 75/25 and a water content of 22%. Results have shown that increasing lime content or dry density or using brackish water allowed to increase unconfined compression strength of swelling soil-SCBA-lime blends. The porosity/volumetric content of lime index (η/Liv) was suitable to predict the unconfined compressive strength of swelling soil-SCBA-lime blends, no matter if tap or brackish water was used in the molding process. Thus, brackish can be a feasible substitute for tap water in swelling soil-SCBA-lime stabilization, increasing blends unconfined compression strength, and preserving tap water, a scarce asset in Northeast Brazil.
{"title":"Brackish water in swelling soil stabilization with lime and sugarcane bagasse ash (SCBA)","authors":"C. Silvani, J. Guedes, Jucimara Silva, Eduardo Tenório, Renan Nascimento","doi":"10.28927/sr.2023.010022","DOIUrl":"https://doi.org/10.28927/sr.2023.010022","url":null,"abstract":"This research shows that brackish water increases the unconfined compressive strength of swelling soil/sugarcane bagasse ash (SCBA)/lime blends. Therefore, brackish water may substitute tap water in soil stabilization. Sodium chloride (NaCl) has been used in lime-ashes-soil treatments. In northeast Brazil, swelling soils are usual and artesian wells sometimes provide brackish water containing NaCl. Northeast Brazil also has a strong sugar and ethanol industry producing sugarcane bagasse ash (SCBA) as a byproduct. Therefore, brackish water can be used in soil-SCBA-lime stabilization. Hence, this work aims to evaluate the use of brackish water as a substitute for tap water in swelling soil- SCBA-lime blends stabilization. Two series of unconfined compression tests were carried out: one with tap water and the other with brackish water. In each group, the lime content varied from 4% to 8%, and the dry density from 13 kN/m3 to 15 kN/m3. All tests were carried out with a swelling soil-SCBA proportion of 75/25 and a water content of 22%. Results have shown that increasing lime content or dry density or using brackish water allowed to increase unconfined compression strength of swelling soil-SCBA-lime blends. The porosity/volumetric content of lime index (η/Liv) was suitable to predict the unconfined compressive strength of swelling soil-SCBA-lime blends, no matter if tap or brackish water was used in the molding process. Thus, brackish can be a feasible substitute for tap water in swelling soil-SCBA-lime stabilization, increasing blends unconfined compression strength, and preserving tap water, a scarce asset in Northeast Brazil.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47732587","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 work presents the validation of the Morgenstern-Price method implemented in the Risk Assessment applied to Slope Stability (RASS) computational program to carry out deterministic and probabilistic analyses of slope stability. Deterministic analyses, based on the factor of safety approach, are performed using limit equilibrium methods. The probabilistic ones, on the other hand, are carried out through the direct coupling of these methods to the First Order Reliability Method (FORM). Initially, two benchmark cases are presented for validation of the computational routine related to the Morgenstern-Price method. Next, two illustrative examples are presented, with the investigation of the critical surfaces defined by deterministic and probabilistic criteria, which correspond to the minimum factor of safety, the maximum probability of failure, and the maximum quantitative risk. In the set of stability analyses, it was verified that both the numerical responses and the geometry of the critical surfaces can vary depending on the choice of the limit equilibrium method and the criterion for identifying the critical surface. The different possibilities presented by the methodology used in this study define not only a critical surface, but a set of critical surfaces that can help in the engineering decision-making process and slope risk management, complementing the widely used purely deterministic analyses in geotechnics.
{"title":"Comparative study of deterministic and probabilistic critical slip surfaces applied to slope stability using limit equilibrium methods and the First-Order Reliability Method","authors":"H. Assis, C. Nogueira","doi":"10.28927/sr.2023.013522","DOIUrl":"https://doi.org/10.28927/sr.2023.013522","url":null,"abstract":"This work presents the validation of the Morgenstern-Price method implemented in the Risk Assessment applied to Slope Stability (RASS) computational program to carry out deterministic and probabilistic analyses of slope stability. Deterministic analyses, based on the factor of safety approach, are performed using limit equilibrium methods. The probabilistic ones, on the other hand, are carried out through the direct coupling of these methods to the First Order Reliability Method (FORM). Initially, two benchmark cases are presented for validation of the computational routine related to the Morgenstern-Price method. Next, two illustrative examples are presented, with the investigation of the critical surfaces defined by deterministic and probabilistic criteria, which correspond to the minimum factor of safety, the maximum probability of failure, and the maximum quantitative risk. In the set of stability analyses, it was verified that both the numerical responses and the geometry of the critical surfaces can vary depending on the choice of the limit equilibrium method and the criterion for identifying the critical surface. The different possibilities presented by the methodology used in this study define not only a critical surface, but a set of critical surfaces that can help in the engineering decision-making process and slope risk management, complementing the widely used purely deterministic analyses in geotechnics.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43109729","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 maximum shear modulus (G0) and the modulus degradation curve (G/G0 versus γ) are important information in the evaluation of the soil mechanical behavior, both for dynamic and static loads. Dynamic tests (resonant column and cyclic triaxial tests) are not routinely performed in geotechnical practice in Brazil, and the geotechnical literature on the dynamic behavior of unsaturated tropical soils is limited. This paper presents and discusses seismic dilatometer (SDMT), resonant column, and triaxial test with bender elements and internal instrumentation to determine G0 and the modulus degradation curve in an unsaturated tropical sandy soil profile. It was observed that G0 tends to increase non-linearly with soil suction and net stress (σ - ua). It was also observed that the in situ G0 values determined with the SDMT were higher than those from laboratory tests (bender elements and resonant column). The modulus degradation curves determined with resonant column were used to define the reference curve via SDMT for the studied site. Soil suction influence in shear modulus degradation curves determined with unsaturated triaxial compression tests with local instrumentation is also presented and discussed.
{"title":"Maximum shear modulus and modulus degradation curves of an unsaturated tropical soil","authors":"Jeferson Fernandes, B. Rocha, H. Giacheti","doi":"10.28927/sr.2023.013122","DOIUrl":"https://doi.org/10.28927/sr.2023.013122","url":null,"abstract":"The maximum shear modulus (G0) and the modulus degradation curve (G/G0 versus γ) are important information in the evaluation of the soil mechanical behavior, both for dynamic and static loads. Dynamic tests (resonant column and cyclic triaxial tests) are not routinely performed in geotechnical practice in Brazil, and the geotechnical literature on the dynamic behavior of unsaturated tropical soils is limited. This paper presents and discusses seismic dilatometer (SDMT), resonant column, and triaxial test with bender elements and internal instrumentation to determine G0 and the modulus degradation curve in an unsaturated tropical sandy soil profile. It was observed that G0 tends to increase non-linearly with soil suction and net stress (σ - ua). It was also observed that the in situ G0 values determined with the SDMT were higher than those from laboratory tests (bender elements and resonant column). The modulus degradation curves determined with resonant column were used to define the reference curve via SDMT for the studied site. Soil suction influence in shear modulus degradation curves determined with unsaturated triaxial compression tests with local instrumentation is also presented and discussed.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43720960","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}
Predicting the pile’s load capacity is one of the first steps of foundation engineering design. In geotechnical engineering, there are different ways of predicting soil resistance, which is one of the main parameters. The pile load test is the most accurate method to predict bearing capacity in foundations, as it is the most accurate due to the nature of the experiment. On the other hand, it is an expensive test, and time-consuming. Over the years, semi-empirical methods have played an important role in this matter. Initially, many proposed methods were based on linear regressions. Those are still mainly used, but recently the use of a new method has gained popularity in Geotechnics: Artificial Neural Network. Over the past few decades, Machine Learning has proven to be a very promising technique in the field, due to the complexity and variability of material and properties of soils. Considering that, this work has reviewed and mapped the literature of the main papers published in journals over the last decades. The aim of this paper was to determine the main methods used and lacks that can be fulfilled in future research. Among the results, the bibliometric and protocol aiming questions such as types of piles, tests, statistic methods, and characteristics inherent to the data, indicated a lack of works in helical piles and instrumented pile load tests results, dividing point and shaft resistance.
{"title":"Systematic literature review and mapping of the prediction of pile capacities","authors":"Sofia Carvalho, M. Sales, André Cavalcante","doi":"10.28927/sr.2023.011922","DOIUrl":"https://doi.org/10.28927/sr.2023.011922","url":null,"abstract":"Predicting the pile’s load capacity is one of the first steps of foundation engineering design. In geotechnical engineering, there are different ways of predicting soil resistance, which is one of the main parameters. The pile load test is the most accurate method to predict bearing capacity in foundations, as it is the most accurate due to the nature of the experiment. On the other hand, it is an expensive test, and time-consuming. Over the years, semi-empirical methods have played an important role in this matter. Initially, many proposed methods were based on linear regressions. Those are still mainly used, but recently the use of a new method has gained popularity in Geotechnics: Artificial Neural Network. Over the past few decades, Machine Learning has proven to be a very promising technique in the field, due to the complexity and variability of material and properties of soils. Considering that, this work has reviewed and mapped the literature of the main papers published in journals over the last decades. The aim of this paper was to determine the main methods used and lacks that can be fulfilled in future research. Among the results, the bibliometric and protocol aiming questions such as types of piles, tests, statistic methods, and characteristics inherent to the data, indicated a lack of works in helical piles and instrumented pile load tests results, dividing point and shaft resistance.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44625217","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}
Limited availability of simple yet adequately validated tools for estimating the deformation potential of municipal solid waste (MSW) material poses difficulty in planning and managing landfill operations. Estimation of settlement of MSW landfills has remained a challenge because of heterogeneity and time-varying mechanical behavior of MSW materials and difficulty of extracting representative samples and reconstituting them for laboratory testing. An empirical correlation is proposed here for estimating the short-term settlement of landfill materials. The relationship was developed by calibrating laboratory data from axial (1D) compression and consolidated drained triaxial tests against field-measured shear wave velocities from five landfill sites with varied waste compositions. The correlation was validated against three full scale load tests; one obtained in this research and two reported by others, and a field compaction study from a fourth landfill. Although the proposed correlation was more accurate than an alternative developed earlier, overall it underestimated settlements by about 12%. The proposed relationship could therefore provide a conservative guidance in MSW landfill design and operation.
{"title":"Estimation of short-term settlements of MSW landfill materials using shear wave velocity","authors":"","doi":"10.28927/sr.2023.078521","DOIUrl":"https://doi.org/10.28927/sr.2023.078521","url":null,"abstract":"Limited availability of simple yet adequately validated tools for estimating the deformation potential of municipal solid waste (MSW) material poses difficulty in planning and managing landfill operations. Estimation of settlement of MSW landfills has remained a challenge because of heterogeneity and time-varying mechanical behavior of MSW materials and difficulty of extracting representative samples and reconstituting them for laboratory testing. An empirical correlation is proposed here for estimating the short-term settlement of landfill materials. The relationship was developed by calibrating laboratory data from axial (1D) compression and consolidated drained triaxial tests against field-measured shear wave velocities from five landfill sites with varied waste compositions. The correlation was validated against three full scale load tests; one obtained in this research and two reported by others, and a field compaction study from a fourth landfill. Although the proposed correlation was more accurate than an alternative developed earlier, overall it underestimated settlements by about 12%. The proposed relationship could therefore provide a conservative guidance in MSW landfill design and operation.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43409947","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}
Raphael Carneiro, K. Guerra, C. Romanel, D. Gerscovich, B. Danziger
In engineering practice, loading varies with time. However, the classical one-dimensional theory of consolidation assumes the stress increase is instantaneously applied. Many approaches to the problem of time-dependent loading have been proposed over the years, from approximate methods to full developments of differential equations. The paper presents a simple method for finding a closed-form consolidation solution for time-dependent loading without the need for differential equations. Two sets of general equations were derived for both excess pore pressure and average degree of consolidation. Equations were solved for linear, parabolic, sinusoidal, and exponential load functions. Stepped and cyclic loads were also addressed and a numerical solution was developed to verify the obtained result. The method proved to be easy to apply and provides solutions with great simplicity. A case study of non-instantaneous loading on soft clay was also analyzed, and settlement prediction showed good results when compared to readings of the settlement plates.
{"title":"Closed-form consolidation solutions for known loading functions","authors":"Raphael Carneiro, K. Guerra, C. Romanel, D. Gerscovich, B. Danziger","doi":"10.28927/sr.2023.077721","DOIUrl":"https://doi.org/10.28927/sr.2023.077721","url":null,"abstract":"In engineering practice, loading varies with time. However, the classical one-dimensional theory of consolidation assumes the stress increase is instantaneously applied. Many approaches to the problem of time-dependent loading have been proposed over the years, from approximate methods to full developments of differential equations. The paper presents a simple method for finding a closed-form consolidation solution for time-dependent loading without the need for differential equations. Two sets of general equations were derived for both excess pore pressure and average degree of consolidation. Equations were solved for linear, parabolic, sinusoidal, and exponential load functions. Stepped and cyclic loads were also addressed and a numerical solution was developed to verify the obtained result. The method proved to be easy to apply and provides solutions with great simplicity. A case study of non-instantaneous loading on soft clay was also analyzed, and settlement prediction showed good results when compared to readings of the settlement plates.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45504264","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 use of deep foundations is a common practice in geotechnical civil engineering designs, in which the bearing capacity of these foundations occurs by side resistance, tip, or through the combination of both. In the case of caisson, the bearing capacity is often obtained by considering only the resistance of the lower end due to its bell-shaped geometry, neglecting the skin friction resistance of the shaft, which may represent an oversizing in some cases. In this context, this paper analyzed the behavior of nine caisson prototypes laid at 10 m, 15 m and 20 m deep. At each depth, three types of caissons were analyzed, with and without an expanded base, and a third type with deformable material at the top of the base. The axisymmetric numerical analyses were conducted by using the finite element method considering an isotropic medium. Thus, it was found that with increasing depth, the skin frictional resistance of the surrounding soil of shaft contributes significantly to the bearing capacity of the caisson suggesting that little load would reach the base of the caisson in situations that would negligible the side resistance of the shaft in the design phase. This may be an important consideration in foundation design using caisson, as it would reduce risks to human life, as well as reduce material consumption and the generation of carbon released into the atmosphere.
{"title":"Numerical analysis of the contribution of side resistance to caisson bearing capacity","authors":"Bárbara Pereira, J. Garcia","doi":"10.28927/sr.2023.000123","DOIUrl":"https://doi.org/10.28927/sr.2023.000123","url":null,"abstract":"The use of deep foundations is a common practice in geotechnical civil engineering designs, in which the bearing capacity of these foundations occurs by side resistance, tip, or through the combination of both. In the case of caisson, the bearing capacity is often obtained by considering only the resistance of the lower end due to its bell-shaped geometry, neglecting the skin friction resistance of the shaft, which may represent an oversizing in some cases. In this context, this paper analyzed the behavior of nine caisson prototypes laid at 10 m, 15 m and 20 m deep. At each depth, three types of caissons were analyzed, with and without an expanded base, and a third type with deformable material at the top of the base. The axisymmetric numerical analyses were conducted by using the finite element method considering an isotropic medium. Thus, it was found that with increasing depth, the skin frictional resistance of the surrounding soil of shaft contributes significantly to the bearing capacity of the caisson suggesting that little load would reach the base of the caisson in situations that would negligible the side resistance of the shaft in the design phase. This may be an important consideration in foundation design using caisson, as it would reduce risks to human life, as well as reduce material consumption and the generation of carbon released into the atmosphere.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42781315","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}
Maximum shear modulus (G0) has been used in various geotechnical jobs (e.g., seismic site assessment, machine vibration and pile driven). Laboratory and in situ determination of G0 is not a current practice in Brazil. G0 can be estimated from empirical correlations based on in situ tests like Standard Penetration Test (SPT) and Cone Penetration Test (CPT) in the preliminary design phase. Several empirical correlations to estimate G0 from SPT N value have been developed and are available in the literature. However, most of these correlations were established based on experience with well-behaved soils formed in temperate and glacial zones, which may not always be used for tropical soils. This paper assessed and discussed the applicability of some correlations for G0 estimative from SPT data in lateritic and saprolitic soils. The classical correlations for sedimentary soils underestimated G0 of tropical soils. After updating the database, the tropical soils correlations reasonably estimated G0 for the lateritic ones, which was not the case for the saprolitic soils. It was observed that differentiating the soils only as lateritic or saprolitic was not adequate for a good G0 estimate for the saprolitic sandy soils. It was found that only the lateritic soils correlation can be used with caution as a preliminary attempt to estimate G0 from SPT N value in soils with similar characteristics to the ones presented in this paper.
{"title":"Maximum shear modulus estimative from SPT for some Brazilian tropical soils","authors":"B. Rocha, Bruno Silva, H. Giacheti","doi":"10.28927/sr.2023.005222","DOIUrl":"https://doi.org/10.28927/sr.2023.005222","url":null,"abstract":"Maximum shear modulus (G0) has been used in various geotechnical jobs (e.g., seismic site assessment, machine vibration and pile driven). Laboratory and in situ determination of G0 is not a current practice in Brazil. G0 can be estimated from empirical correlations based on in situ tests like Standard Penetration Test (SPT) and Cone Penetration Test (CPT) in the preliminary design phase. Several empirical correlations to estimate G0 from SPT N value have been developed and are available in the literature. However, most of these correlations were established based on experience with well-behaved soils formed in temperate and glacial zones, which may not always be used for tropical soils. This paper assessed and discussed the applicability of some correlations for G0 estimative from SPT data in lateritic and saprolitic soils. The classical correlations for sedimentary soils underestimated G0 of tropical soils. After updating the database, the tropical soils correlations reasonably estimated G0 for the lateritic ones, which was not the case for the saprolitic soils. It was observed that differentiating the soils only as lateritic or saprolitic was not adequate for a good G0 estimate for the saprolitic sandy soils. It was found that only the lateritic soils correlation can be used with caution as a preliminary attempt to estimate G0 from SPT N value in soils with similar characteristics to the ones presented in this paper.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47409135","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 need to develop and commercialize materials incorporating vegetable fibers has risen over the last 20 years to decrease environmental impact and achieve sustainability. In geotechnical engineering, soil reinforcement with plant-based fibers has gained a lot of interest, especially in temporary earthworks. Soil reinforcement with plant-based fibers is a low-cost, environmentally friendly method with excellent reproducibility and accessibility. In this context, growing appeals for using plant-based fibers such as sisal, coir, curauá, and kenaf for manufacturing new geomaterials have been verified. This paper aims to evaluate the mechanical behavior of soil-fiber composites by insertion of natural coir fibers into a sandy soil matrix with different fiber lengths and contents, where the fibers were randomly distributed in the soil mass. Large-scale direct shear test evaluated the strength-displacement behavior in samples with dimensions of 300 x 300 mm and 200 mm in height. The tests were carried out using fibers with 25 and 50 mm lengths, in 0.50 and 0.75% of fiber contents (in relation to the dry weight of the soil), in a relative density of 50% and 10% moisture content. The overall analysis of the results showed that the coir fibers addition in the well-graded sand increased the shear strength parameters and the ductility, compared with the unreinforced sand.
在过去的20年里，开发和商业化含有植物纤维的材料的需求不断增加，以减少对环境的影响并实现可持续性。在岩土工程中，植物纤维加固土壤引起了人们的广泛兴趣，尤其是在临时土方工程中。植物纤维加固土壤是一种低成本、环保的方法，具有良好的再现性和可及性。在这种情况下，越来越多的人呼吁使用剑麻、椰壳、curauá和红麻等植物纤维来制造新的土工材料，这一点已经得到了证实。本文旨在通过将天然椰纤维插入不同纤维长度和含量的沙质土壤基质中，评估土壤纤维复合材料的力学性能，其中纤维随机分布在土体中。大型直剪试验评估了尺寸为300 x 300 mm和200 mm高的样品的强度-位移行为。使用长度分别为25和50 mm的纤维，纤维含量分别为0.50和0.75%（相对于土壤干重），相对密度分别为50%和10%的含水量进行试验。结果的总体分析表明，与未加筋砂相比，在级配良好的砂中加入椰纤维可以提高抗剪强度参数和延性。
{"title":"Large-scale direct shear testing in coir fibers reinforced sand","authors":"Leila Carvalho, F. Monteiro, M. Casagrande","doi":"10.28927/sr.2023.002822","DOIUrl":"https://doi.org/10.28927/sr.2023.002822","url":null,"abstract":"The need to develop and commercialize materials incorporating vegetable fibers has risen over the last 20 years to decrease environmental impact and achieve sustainability. In geotechnical engineering, soil reinforcement with plant-based fibers has gained a lot of interest, especially in temporary earthworks. Soil reinforcement with plant-based fibers is a low-cost, environmentally friendly method with excellent reproducibility and accessibility. In this context, growing appeals for using plant-based fibers such as sisal, coir, curauá, and kenaf for manufacturing new geomaterials have been verified. This paper aims to evaluate the mechanical behavior of soil-fiber composites by insertion of natural coir fibers into a sandy soil matrix with different fiber lengths and contents, where the fibers were randomly distributed in the soil mass. Large-scale direct shear test evaluated the strength-displacement behavior in samples with dimensions of 300 x 300 mm and 200 mm in height. The tests were carried out using fibers with 25 and 50 mm lengths, in 0.50 and 0.75% of fiber contents (in relation to the dry weight of the soil), in a relative density of 50% and 10% moisture content. The overall analysis of the results showed that the coir fibers addition in the well-graded sand increased the shear strength parameters and the ductility, compared with the unreinforced sand.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47367056","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 effect of soil constitutive models, nonlinearity of the barrette material, loading direction as well as the cross-sectional shape and second moment of inertia on the response the barrette foundation under lateral loading is investigated in this research. The numerical analyses were conducted on a well-documented barrette load test using Plaxis 3D. The investigation results revealed that the response of the barrette is significantly affected by the direction of the applied load and nonlinear behavior of the soil and barrette materials. For rectangular, square, and circular piles with different cross-section areas and same second moment of inertia, the square and circular piles exhibit similar behavior but different from that of the rectangular pile. However, when these piles have the same cross-section area and different second moments of inertia, the behavior of rectangular pile is close to that of square pile when the load is applied along the x direction and is close to that of circular pile shape when the load is applied along the y direction.
{"title":"Numerical analysis of laterally loaded barrette foundation","authors":"Djamila Behloul, S. Rafa, B. Moussai","doi":"10.28927/sr.2023.002122","DOIUrl":"https://doi.org/10.28927/sr.2023.002122","url":null,"abstract":"The effect of soil constitutive models, nonlinearity of the barrette material, loading direction as well as the cross-sectional shape and second moment of inertia on the response the barrette foundation under lateral loading is investigated in this research. The numerical analyses were conducted on a well-documented barrette load test using Plaxis 3D. The investigation results revealed that the response of the barrette is significantly affected by the direction of the applied load and nonlinear behavior of the soil and barrette materials. For rectangular, square, and circular piles with different cross-section areas and same second moment of inertia, the square and circular piles exhibit similar behavior but different from that of the rectangular pile. However, when these piles have the same cross-section area and different second moments of inertia, the behavior of rectangular pile is close to that of square pile when the load is applied along the x direction and is close to that of circular pile shape when the load is applied along the y direction.","PeriodicalId":43687,"journal":{"name":"Soils and Rocks","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47887725","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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