Abstract This technical article presents the influence of sample quality on the compressibility parameters and undrained shear strength ( c u ) of soft soils from the Vistula Marshlands. The analysis covers: (1) quality of soft soil according to three criteria: void ratio (Δ e / e 0 index), volumetric strain (Δ ɛ v ) and C r / C c ratio; (2) influence of storage time on quality; (3) influence of sample quality on undrained shear strength ( c u ), and (4) reliability of compression and undrained shear strength parameters estimation. The sample quality of three different soft soils (peat, organic clays, and organic silts) was investigated using dataset of geotechnical investigations from the Vistula Marshlands. The reliability of oedometer tests and compressibility parameters determination was shown. Different undrained shear strength estimates (from lab and field tests) were juxtaposed with sample quality. In situ estimates of undrained shear strength were compared with results of triaxial tests and direct simple shear test on reconstituted samples as well as SHANSEP estimates. The results of research are grouped in seven lessons. The most important outcomes are: (1) the quality of samples is at best moderate or poor and there is no significant influence of storage time on sample quality, (2) regardless of testing method, the undrained shear strength natural variability of the Vistula Marshlands soft soils is between 20% and 50% depending on deposit depth and soil type, (3) the most accurate estimation of undrained shear strength can be obtained from field vane test (FVT) while unconsolidated, undrained compression (UUC) triaxial tests should be avoided, (4) SHANSEP approach can be considered as a valuable estimate of c u (next to the FVTs), which additionally allows in relatively easy way to establish lower and upper bounds of c u .
摘要本文研究了不同试样质量对维斯瓦湿地软土压缩性参数和不排水抗剪强度(cu)的影响。分析内容包括:(1)软土质量按孔隙比(Δ e / e 0指数)、体积应变(Δ e / e 0指数)和C r / C C比三个标准进行分析;(2)贮存时间对品质的影响;(3)试样质量对不排水抗剪强度的影响(c u);(4)抗压和不排水抗剪强度参数估计的可靠性。利用维斯瓦沼泽的岩土工程调查数据，研究了三种不同软土(泥炭、有机粘土和有机粉砂)的样品质量。证明了测径仪试验和压缩系数测定的可靠性。不同的不排水剪切强度估计(从实验室和现场试验)与样品质量并列。对比了三轴试验、直接单剪试验和SHANSEP估算的原位不排水抗剪强度。研究结果分为七课。最重要的结果是:(1)样品质量最多为中等或较差，存放时间对样品质量没有显著影响;(2)无论采用何种测试方法，湿地软土的不排水抗剪强度自然变异性在20% ~ 50%之间，具体取决于沉积深度和土壤类型;(3)松散状态下，不排水抗剪强度最准确的估算方法是现场叶片试验(FVT);应避免不排水压缩(UUC)三轴试验，(4)SHANSEP方法可以被认为是一个有价值的cu估计(仅次于fvt)，它还允许以相对容易的方式建立cu的下界和上界。
{"title":"Influence of Soft Soil Samples Quality on the Compressibility and Undrained Shear Strength – Seven Lessons Learned From the Vistula Marshlands","authors":"Jakub Konkol","doi":"10.2478/sgem-2023-0012","DOIUrl":"https://doi.org/10.2478/sgem-2023-0012","url":null,"abstract":"Abstract This technical article presents the influence of sample quality on the compressibility parameters and undrained shear strength ( c u ) of soft soils from the Vistula Marshlands. The analysis covers: (1) quality of soft soil according to three criteria: void ratio (Δ e / e 0 index), volumetric strain (Δ ɛ v ) and C r / C c ratio; (2) influence of storage time on quality; (3) influence of sample quality on undrained shear strength ( c u ), and (4) reliability of compression and undrained shear strength parameters estimation. The sample quality of three different soft soils (peat, organic clays, and organic silts) was investigated using dataset of geotechnical investigations from the Vistula Marshlands. The reliability of oedometer tests and compressibility parameters determination was shown. Different undrained shear strength estimates (from lab and field tests) were juxtaposed with sample quality. In situ estimates of undrained shear strength were compared with results of triaxial tests and direct simple shear test on reconstituted samples as well as SHANSEP estimates. The results of research are grouped in seven lessons. The most important outcomes are: (1) the quality of samples is at best moderate or poor and there is no significant influence of storage time on sample quality, (2) regardless of testing method, the undrained shear strength natural variability of the Vistula Marshlands soft soils is between 20% and 50% depending on deposit depth and soil type, (3) the most accurate estimation of undrained shear strength can be obtained from field vane test (FVT) while unconsolidated, undrained compression (UUC) triaxial tests should be avoided, (4) SHANSEP approach can be considered as a valuable estimate of c u (next to the FVTs), which additionally allows in relatively easy way to establish lower and upper bounds of c u .","PeriodicalId":44626,"journal":{"name":"Studia Geotechnica et Mechanica","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136280609","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}
Abstract This article presents an engineering, empirical method of estimating the bearing capacity and settlement characteristics Q-s of screw displacement piles and columns, based on soil resistance encountered during the drilling to form piles/columns in the ground. The method was developed on the basis of correlation analyses of the test results of 24 piles made during the “DPDT-Auger” research project (Krasiński et al., 2022a). In the proposed method, the load capacity of a screw displacement pile is estimated using two main parameters of auger screwing resistance: torque M T and the number of auger rotations per depth unit n R . The method applies to piles and columns made with a standard screw displacement pile (SDP) auger and with the proprietary, prototype DPDT ( displacement pile drilling tool ) aguer, patented in Poland (2020). Based on the estimated ultimate capacities of the pile shaft and base, an approximate method of predicting the pile settlement characteristics Q-s was also proposed, using the transfer function method. This article describes a correlation procedure of field test results together with their statistical analysis and presents a method of estimating the pile-bearing capacity based on correlation results. A calculation example is also provided. The conclusion looks at the useful practical applications that could be found for the proposed method.
摘要本文提出了一种基于钻孔成桩/柱过程中遇到的土阻力估算螺旋位移桩/柱承载力及沉降特性Q-s的工程经验方法。该方法是在“DPDT-Auger”研究项目(Krasiński et al.， 2022a)中对24桩试验结果进行相关性分析的基础上发展起来的。该方法利用螺旋钻旋入阻力的两个主要参数:扭矩M T和螺旋钻每深度单位旋转数n R来估计螺旋位移桩的承载能力。该方法适用于使用标准螺杆位移桩(SDP)螺旋钻机和专利的原型DPDT(位移桩钻孔工具)aguer(在波兰获得专利(2020年))制成的桩和柱。在估计桩身和桩底极限承载力的基础上，提出了一种用传递函数法近似预测桩沉降特性Q-s的方法。本文介绍了现场试验结果的关联过程及其统计分析，提出了一种基于关联结果估算桩承载力的方法。并给出了计算实例。结论部分探讨了所提方法的实际应用。
{"title":"Estimation of Screw Displacement Pile-Bearing Capacity Based on Drilling Resistances","authors":"Adam Krasiński","doi":"10.2478/sgem-2023-0014","DOIUrl":"https://doi.org/10.2478/sgem-2023-0014","url":null,"abstract":"Abstract This article presents an engineering, empirical method of estimating the bearing capacity and settlement characteristics Q-s of screw displacement piles and columns, based on soil resistance encountered during the drilling to form piles/columns in the ground. The method was developed on the basis of correlation analyses of the test results of 24 piles made during the “DPDT-Auger” research project (Krasiński et al., 2022a). In the proposed method, the load capacity of a screw displacement pile is estimated using two main parameters of auger screwing resistance: torque M T and the number of auger rotations per depth unit n R . The method applies to piles and columns made with a standard screw displacement pile (SDP) auger and with the proprietary, prototype DPDT ( displacement pile drilling tool ) aguer, patented in Poland (2020). Based on the estimated ultimate capacities of the pile shaft and base, an approximate method of predicting the pile settlement characteristics Q-s was also proposed, using the transfer function method. This article describes a correlation procedure of field test results together with their statistical analysis and presents a method of estimating the pile-bearing capacity based on correlation results. A calculation example is also provided. The conclusion looks at the useful practical applications that could be found for the proposed method.","PeriodicalId":44626,"journal":{"name":"Studia Geotechnica et Mechanica","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136280295","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}
Abstract The effect of the degree of consolidation and the stress path on the behaviour of remoulded Fujinomori clay for drained triaxial compression and extension was analysed using the Frictional State Concept. It is shown that the stress–dilatancy behaviour can be approximated by a linear general dilatancy equation given by the critical frictional state angle and two soil parameters. The newly formulated dilatant failure state is represented on the stress ratio plastic dilatancy plane by points lying on the friction state line defined by the friction state angle and the Friction State Concept parameters α =0 and β =1. It has been shown that the stress ratio–plastic dilatancy relationship, which is very rarely used in the interpretation of test results, is important for a complete description of the behaviour of soils during shearing.
{"title":"Stress–dilatancy behaviour of remoulded Fujinomori clay","authors":"Zenon Szypcio, Katarzyna Dołżyk-Szypcio","doi":"10.2478/sgem-2023-0010","DOIUrl":"https://doi.org/10.2478/sgem-2023-0010","url":null,"abstract":"Abstract The effect of the degree of consolidation and the stress path on the behaviour of remoulded Fujinomori clay for drained triaxial compression and extension was analysed using the Frictional State Concept. It is shown that the stress–dilatancy behaviour can be approximated by a linear general dilatancy equation given by the critical frictional state angle and two soil parameters. The newly formulated dilatant failure state is represented on the stress ratio plastic dilatancy plane by points lying on the friction state line defined by the friction state angle and the Friction State Concept parameters α =0 and β =1. It has been shown that the stress ratio–plastic dilatancy relationship, which is very rarely used in the interpretation of test results, is important for a complete description of the behaviour of soils during shearing.","PeriodicalId":44626,"journal":{"name":"Studia Geotechnica et Mechanica","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135734364","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. Roustaei, Mahdi Sabetraftar, E. Taherabadi, M. Bayat
Abstract Improvement of the mechanical properties of clayey soils by additional elements to enhance the strength under numerous freezing and thawing cycles has been considered as a serious concern for engineering applications in cold regions. The objective of the current study is to investigate the effect of nano-clay as a stabiliser on the mechanical properties of clay. To this end, the clay specimens were prepared by adding various percentages of nano-clay ranging from 0.5% to 3% by dry weight of soil and were experimentally tested under the uniaxial compression and tensile splitting tests under different curing times (0, 7 and 28 days) after experiencing various freeze–thaw cycles ranging from 0 to 11. It can be concluded from the results that nano-clay particles may be used as a stabiliser in geotechnical applications to improve soil property. The results indicate that the optimum moisture content (OMC) of specimens increases and the maximum dry density (MDD) decreases with the increasing nano-clay content. The specimens containing about 1% nano-clay recorded maximum values of unconfined compressive strength (UCS) as well as tensile strength. For example, the addition 1% nano-clay increased the UCS and tensile values of clay specimens under the curing time of 28 days by 34% and 247%, respectively. In addition, the long-term durability of specimens against freeze–thaw cycles increases further with the addition of nano-clay content ranging from 2% to 3%.
{"title":"Compressive and Tensile Strength of Nano-clay Stabilised Soil Subjected to Repeated Freeze–Thaw Cycles","authors":"M. Roustaei, Mahdi Sabetraftar, E. Taherabadi, M. Bayat","doi":"10.2478/sgem-2023-0009","DOIUrl":"https://doi.org/10.2478/sgem-2023-0009","url":null,"abstract":"Abstract Improvement of the mechanical properties of clayey soils by additional elements to enhance the strength under numerous freezing and thawing cycles has been considered as a serious concern for engineering applications in cold regions. The objective of the current study is to investigate the effect of nano-clay as a stabiliser on the mechanical properties of clay. To this end, the clay specimens were prepared by adding various percentages of nano-clay ranging from 0.5% to 3% by dry weight of soil and were experimentally tested under the uniaxial compression and tensile splitting tests under different curing times (0, 7 and 28 days) after experiencing various freeze–thaw cycles ranging from 0 to 11. It can be concluded from the results that nano-clay particles may be used as a stabiliser in geotechnical applications to improve soil property. The results indicate that the optimum moisture content (OMC) of specimens increases and the maximum dry density (MDD) decreases with the increasing nano-clay content. The specimens containing about 1% nano-clay recorded maximum values of unconfined compressive strength (UCS) as well as tensile strength. For example, the addition 1% nano-clay increased the UCS and tensile values of clay specimens under the curing time of 28 days by 34% and 247%, respectively. In addition, the long-term durability of specimens against freeze–thaw cycles increases further with the addition of nano-clay content ranging from 2% to 3%.","PeriodicalId":44626,"journal":{"name":"Studia Geotechnica et Mechanica","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42793595","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}
Abstract The algorithm presented in this paper concerns the processing of data in the form of coordinates of measurement points located around the structure periphery, obtained from the geodetic measurements. The geometric parameter used here to study the deformation of the steel shell is the change of curvature. It is used to estimate the bending moment and hence the normal stress in the corrugated steel shell. The results given in the examples of calculations of the analyzed structure show the possibility of determining places with extreme values. For this purpose, a dense layout of measuring points and use the precision geodesy technique is necessary. Of significant importance in stress estimation is the correction of the geodetic measurement base. This is due to the fact that the points in the initial measurement do not lie on a section of the circle as a reference curve, used to determine the deformation of the shell.
{"title":"Shell Deformation During the Construction of Record Span Soil-steel Buried Structure in Ras-Al-Khaimah (UAE)","authors":"Czesław Machelski, Piotr Tomala","doi":"10.2478/sgem-2023-0007","DOIUrl":"https://doi.org/10.2478/sgem-2023-0007","url":null,"abstract":"Abstract The algorithm presented in this paper concerns the processing of data in the form of coordinates of measurement points located around the structure periphery, obtained from the geodetic measurements. The geometric parameter used here to study the deformation of the steel shell is the change of curvature. It is used to estimate the bending moment and hence the normal stress in the corrugated steel shell. The results given in the examples of calculations of the analyzed structure show the possibility of determining places with extreme values. For this purpose, a dense layout of measuring points and use the precision geodesy technique is necessary. Of significant importance in stress estimation is the correction of the geodetic measurement base. This is due to the fact that the points in the initial measurement do not lie on a section of the circle as a reference curve, used to determine the deformation of the shell.","PeriodicalId":44626,"journal":{"name":"Studia Geotechnica et Mechanica","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135639025","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}
Abstract Ground movements induced by deep excavations may cause damages on neighboring existing buildings. Finite element simulations generally give acceptable estimates of the horizontal displacements of the retaining wall, but results are less satisfactory for the vertical displacements of the ground surface behind the structure. A possible explanation is that most constitutive models describe volumetric strains in a simplified way. This paper proposes an elastoplastic constitutive model aimed at improving the prediction of vertical displacements behind retaining walls. The model comprises a single plastic mechanism with isotropic strain hardening, but has a specific flow rule that allows to generate contractive plastic strains. Identification of the parameters based on triaxial tests is explained and illustrated by an example of calibration. A numerical analysis of a well-documented sheet pile wall in sand in Hochstetten (Germany) is presented. The results given by the model are compared with the measurements and with those obtained using the Hardening Soil Model. The potential advantages of the proposed model are then discussed.
{"title":"An elastoplastic constitutive model for assessing ground settlements induced by deep excavations","authors":"Hiba El-Arja, Sébastien Burlon, Emmanuel Bourgeois","doi":"10.2478/sgem-2023-0011","DOIUrl":"https://doi.org/10.2478/sgem-2023-0011","url":null,"abstract":"Abstract Ground movements induced by deep excavations may cause damages on neighboring existing buildings. Finite element simulations generally give acceptable estimates of the horizontal displacements of the retaining wall, but results are less satisfactory for the vertical displacements of the ground surface behind the structure. A possible explanation is that most constitutive models describe volumetric strains in a simplified way. This paper proposes an elastoplastic constitutive model aimed at improving the prediction of vertical displacements behind retaining walls. The model comprises a single plastic mechanism with isotropic strain hardening, but has a specific flow rule that allows to generate contractive plastic strains. Identification of the parameters based on triaxial tests is explained and illustrated by an example of calibration. A numerical analysis of a well-documented sheet pile wall in sand in Hochstetten (Germany) is presented. The results given by the model are compared with the measurements and with those obtained using the Hardening Soil Model. The potential advantages of the proposed model are then discussed.","PeriodicalId":44626,"journal":{"name":"Studia Geotechnica et Mechanica","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135484322","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}
A. Herbut, A. Jakubczyk-Gałczyńska, M. Wyjadłowski
Abstract The paper concerns the wide range of strategies used to protect structures against man-made dynamic excitation. The most popular approaches applied worldwide are compared, and the main differences and similarities are summarized. The literature studies are supported by the results of the measurements performed on different types of real structures, which are sensitive and insensitive to the dynamic load. To make the conclusions more general, various types of excitation forces are examined (long-term and short-term excitations, traffic load, and loads resulting from geotechnical works). The main issue raised in the paper is the problem of unequivocal and accurate assessment of the potential structure damage, based on the different legislations. It can be seen that the application of different codes can even result in opposite conclusions about the safety of the structure.
{"title":"Vibration monitoring of structures in the light of the Polish and international requirements","authors":"A. Herbut, A. Jakubczyk-Gałczyńska, M. Wyjadłowski","doi":"10.2478/sgem-2023-0008","DOIUrl":"https://doi.org/10.2478/sgem-2023-0008","url":null,"abstract":"Abstract The paper concerns the wide range of strategies used to protect structures against man-made dynamic excitation. The most popular approaches applied worldwide are compared, and the main differences and similarities are summarized. The literature studies are supported by the results of the measurements performed on different types of real structures, which are sensitive and insensitive to the dynamic load. To make the conclusions more general, various types of excitation forces are examined (long-term and short-term excitations, traffic load, and loads resulting from geotechnical works). The main issue raised in the paper is the problem of unequivocal and accurate assessment of the potential structure damage, based on the different legislations. It can be seen that the application of different codes can even result in opposite conclusions about the safety of the structure.","PeriodicalId":44626,"journal":{"name":"Studia Geotechnica et Mechanica","volume":"0 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41432504","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}
Abstract In this study, a novel method is proposed to optimize the reinforced parameters influencing the bearing capacity of a shallow square foundation resting on sandy soil reinforced with geosynthetic. The parameters to be optimized are reinforcement length (L), the number of reinforcement layers (N), the depth of the topmost layer of geosynthetic (U), and the vertical distance between two reinforcement layers (X). To achieve this objective, 25 laboratory small-scale model tests were conducted on reinforced sand. This laboratory-scale model has used two geosynthetics as reinforcement materials and one sandy soil. Firstly, the effect of reinforcement parameters on the bearing load was investigated using the analysis of variance (ANOVA). Both response surface methodology (RSM) and artificial neural networks (ANN) tools were applied and compared to model bearing capacity. Finally, the multiobjective genetic algorithm (MOGA) coupled with RSM and ANN models was used to solve multi objective optimization problems. The design of bearing capacity is considered a multi-objective optimization problem. In this regard, the two conflicting objectives are the need to maximize bearing capacity and minimize the cost. According to the obtained results, an informed decision regarding the design of the bearing capacity of reinforced sand is reached.
{"title":"A Novel Method for Optimizing Parameters influencing the Bearing Capacity of Geosynthetic Reinforced Sand Using RSM, ANN, and Multi-objective Genetic Algorithm","authors":"Brahim Lafifi, A. Rouaiguia, E. Soltani","doi":"10.2478/sgem-2023-0006","DOIUrl":"https://doi.org/10.2478/sgem-2023-0006","url":null,"abstract":"Abstract In this study, a novel method is proposed to optimize the reinforced parameters influencing the bearing capacity of a shallow square foundation resting on sandy soil reinforced with geosynthetic. The parameters to be optimized are reinforcement length (L), the number of reinforcement layers (N), the depth of the topmost layer of geosynthetic (U), and the vertical distance between two reinforcement layers (X). To achieve this objective, 25 laboratory small-scale model tests were conducted on reinforced sand. This laboratory-scale model has used two geosynthetics as reinforcement materials and one sandy soil. Firstly, the effect of reinforcement parameters on the bearing load was investigated using the analysis of variance (ANOVA). Both response surface methodology (RSM) and artificial neural networks (ANN) tools were applied and compared to model bearing capacity. Finally, the multiobjective genetic algorithm (MOGA) coupled with RSM and ANN models was used to solve multi objective optimization problems. The design of bearing capacity is considered a multi-objective optimization problem. In this regard, the two conflicting objectives are the need to maximize bearing capacity and minimize the cost. According to the obtained results, an informed decision regarding the design of the bearing capacity of reinforced sand is reached.","PeriodicalId":44626,"journal":{"name":"Studia Geotechnica et Mechanica","volume":"45 1","pages":"174 - 196"},"PeriodicalIF":0.6,"publicationDate":"2023-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42536197","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}
Abstract Methane and coal dust explosions are among the most common causes of disasters in hard coal mining. Therefore, it is important for occupational safety in hard coal mines operating under methane and coal dust explosion hazards to identify possible ignition sources, whether due to natural or technical factors. One technical source of ignition can be mechanical sparks generated during operation of mechanical equipment and high surface temperatures of equipment components during operation. This paper presents the methodology and results of thermal imaging and strength testing of roadway support elements under dynamic loading. The goal of the tests was to identify the potential explosive atmosphere ignition sources during the operation of the support under the conditions of rock bursts. The scope of testing encompassed the temperature measurements by means of thermal camera of friction prop and yielding support frame sliding joint elements at yield under dynamic impact loading (simulating a burst). Significant joint element heating and mechanical sparking was observed during the testing of arching yielding support frame sliding joints and straight friction prop joints as a result of friction at yield. Some of the aspects defined in standard PN-EN ISO80079-36:2016 include the maximum temperature T max =150°C for a surface that can accumulate a layer of coal dust. Tests of the friction joints have shown that during impact loading, numerous mechanical sparks are produced at the friction joints of sections of the steel prop, with the surface temperature of the sections starting from 169.6°C and reaching up to 234.1°C. During tests it was also to determined emissivites of the tested sliding joints constructed from V29-V32 secrions depending on corrosion products which consist in range 0.842–0.873. Such a high temperature can initiate an explosive mixture consisting of methane, air and coal dust.
甲烷和煤尘爆炸是硬煤开采中最常见的灾害原因。因此，无论是自然因素还是技术因素，识别可能的点火源对于在甲烷和煤尘爆炸危害下作业的硬煤矿山的职业安全都具有重要意义。机械设备运行过程中产生的机械火花和设备部件在运行过程中的高表面温度可能是一种技术引燃源。本文介绍了动荷载作用下巷道支护构件热成像和强度测试的方法和结果。试验的目的是确定在岩爆条件下支架运行过程中潜在的爆炸性大气点火源。测试范围包括使用热像仪测量摩擦支柱和屈服支撑框架滑动接头元件在动态冲击载荷(模拟爆炸)下屈服时的温度。在屈服摩擦作用下，拱型屈服支撑架滑动节点和直型摩擦支柱节点均出现了明显的节点发热和机械火花现象。标准PN-EN iso80079 - 36:16中定义的一些方面包括最高温度T max =150°C的表面，可以积累一层煤尘。摩擦接头试验表明，在冲击加载过程中，钢支柱截面摩擦接头处产生大量机械火花，截面表面温度从169.6℃开始，最高可达234.1℃。在测试期间，根据腐蚀产物的范围在0.842-0.873之间，还确定了由V29-V32截面构成的被测试滑动接头的发射率。如此高的温度可以引发由甲烷、空气和煤尘组成的爆炸性混合物。
{"title":"Safety of Steel Arch Support Operation During Rock Bursts Under Explosive Atmosphere Conditions","authors":"A. Pytlik, W. Frąc","doi":"10.2478/sgem-2023-0004","DOIUrl":"https://doi.org/10.2478/sgem-2023-0004","url":null,"abstract":"Abstract Methane and coal dust explosions are among the most common causes of disasters in hard coal mining. Therefore, it is important for occupational safety in hard coal mines operating under methane and coal dust explosion hazards to identify possible ignition sources, whether due to natural or technical factors. One technical source of ignition can be mechanical sparks generated during operation of mechanical equipment and high surface temperatures of equipment components during operation. This paper presents the methodology and results of thermal imaging and strength testing of roadway support elements under dynamic loading. The goal of the tests was to identify the potential explosive atmosphere ignition sources during the operation of the support under the conditions of rock bursts. The scope of testing encompassed the temperature measurements by means of thermal camera of friction prop and yielding support frame sliding joint elements at yield under dynamic impact loading (simulating a burst). Significant joint element heating and mechanical sparking was observed during the testing of arching yielding support frame sliding joints and straight friction prop joints as a result of friction at yield. Some of the aspects defined in standard PN-EN ISO80079-36:2016 include the maximum temperature T max =150°C for a surface that can accumulate a layer of coal dust. Tests of the friction joints have shown that during impact loading, numerous mechanical sparks are produced at the friction joints of sections of the steel prop, with the surface temperature of the sections starting from 169.6°C and reaching up to 234.1°C. During tests it was also to determined emissivites of the tested sliding joints constructed from V29-V32 secrions depending on corrosion products which consist in range 0.842–0.873. Such a high temperature can initiate an explosive mixture consisting of methane, air and coal dust.","PeriodicalId":44626,"journal":{"name":"Studia Geotechnica et Mechanica","volume":"45 1","pages":"144 - 157"},"PeriodicalIF":0.6,"publicationDate":"2023-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43549540","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}
Abstract The article presents a prototype steel–concrete bridge with the results of trial load tests. In the design of the structure, new approaches were used, the so-called concept of a hybrid cross section. The obtained results were interpreted against the background of theoretical analysis performed and the experience of the behavior of the existing standard bridge structures. The obtained results are to be the starting point for the development of methods of calculating this type of structure, with particular emphasis on the degree of cracking of the concrete part of the structure. The paper is intended to be a starting point for demonstrating that it is possible to calculate longitudinal shear in the fatigue limit state (of steel dowels) differently than in the fully cracked section. Similarly, it is supposed to be a point of discussion on how to perform a global analysis of hybrid systems.
{"title":"The new railway hybrid bridge in Dąbrowa Górnicza: innovative concept using new design method and results of load tests","authors":"W. Lorenc, B. Bartoszek","doi":"10.2478/sgem-2023-0002","DOIUrl":"https://doi.org/10.2478/sgem-2023-0002","url":null,"abstract":"Abstract The article presents a prototype steel–concrete bridge with the results of trial load tests. In the design of the structure, new approaches were used, the so-called concept of a hybrid cross section. The obtained results were interpreted against the background of theoretical analysis performed and the experience of the behavior of the existing standard bridge structures. The obtained results are to be the starting point for the development of methods of calculating this type of structure, with particular emphasis on the degree of cracking of the concrete part of the structure. The paper is intended to be a starting point for demonstrating that it is possible to calculate longitudinal shear in the fatigue limit state (of steel dowels) differently than in the fully cracked section. Similarly, it is supposed to be a point of discussion on how to perform a global analysis of hybrid systems.","PeriodicalId":44626,"journal":{"name":"Studia Geotechnica et Mechanica","volume":"45 1","pages":"89 - 111"},"PeriodicalIF":0.6,"publicationDate":"2023-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47129026","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：