Reinstallation of mobile jack-up rigs next to existing footprints is a problematic operation because the spudcan located near the footprints is subjected to eccentric and/or inclined loading conditions. Geotech- nical...Reinstallation of mobile jack-up rigs next to existing footprints is a problematic operation because the spudcan located near the footprints is subjected to eccentric and/or inclined loading conditions. Geotech- nical centrifuge studies have measured these loads for combinations of changing footprint geometry, footprint soil properties and the offset of the reinstallation from the footprint centre. These tests have been of full model spudcans in order to accurately measure the combined loads developed. They have not provided information on the mechanisms of failure occurring during this complex installation. Ob- servations from a visualisation test, where a half spudcan is penetrated against a transparent window in a geotechnical centrifuge, are reported in this paper. The mechanisms of failure at different stages during the nenetrntirm are nr^nted展开更多
Geotechnical analyses were carried out to examine the contributions of engineering geological properties of subgrade soils to the failure of the Akure-Ikere Ekiti road,Southwestern Nigeria.Field observations revealed ...Geotechnical analyses were carried out to examine the contributions of engineering geological properties of subgrade soils to the failure of the Akure-Ikere Ekiti road,Southwestern Nigeria.Field observations revealed that the road is in a very poor state of serious deformation and disrepair as most parts of the road alignment have failed.The alignment of the studied road is predominantly underlain by Granite,Charnockites,and Migmatites.Laboratory tests results showed that the natural moisture content ranges from 10.98 to 21.4%,liquid limit from 22.8 to 47.7%,plastic limit from 19.2 to 24.6,plasticity index 3.6 to 26.3%.The grain size analysis revealed that the amount of fines ranges from 15.9 to 49%.Others are linear shrinkage,between 1.4 and 10%,free swell between 25 and 46%,maximum dry density from 1593 to 2016 kg/m,and CBR between 5 and 48%.The specific gravity ranges from 2.64 to 2.74.With reference to AASHTO classification,5% of the samples was classified as A-4,15% classified as A-2-4,40% classified as A-6,while 40% classified as A-7-6.The dominance of fair-to-good California bearing ratio,fair to good maximum dry density,high linear shrinkage and A-7-6,A-6,and A-2-4 soil groups have combined to give fair-to-good geotechnical properties to the studied soils.Generally,the fair to good geotechnical properties of soil of the road under study is an indication that the contribution of subgrade soil to the failure of the highway is negligible.The total breakdown of the road can be traced to substandard engineering specifications which are complemented by a poor drainage system.展开更多
Ultimate bearing capacity(UBC)is a key subject in geotechnical/foundation engineering as it determines the limit of loads imposed on the foundation.The most reliable means of determining UBC is through experiment,but ...Ultimate bearing capacity(UBC)is a key subject in geotechnical/foundation engineering as it determines the limit of loads imposed on the foundation.The most reliable means of determining UBC is through experiment,but it is costly and time-consuming which has led to the development of various models based on the simplified assumptions.The outcomes of the models are usually validated with the experimental results,but a large gap usually exists between them.Therefore,a model that can give a close prediction of the experimental results is imperative.This study proposes a grasshopper optimization algorithm(GOA)and salp swarm algorithm(SSA)to optimize artificial neural networks(ANNs)using the existing UBC experimental database.The performances of the proposed models are evaluated using various statistical indices.The obtained results are compared with the existing models.The proposed models outperformed the existing models.The proposed hybrid GOA-ANN and SSA-ANN models are then transformed into mathematical forms that can be incorporated into geotechnical/foundation engineering design codes for accurate UBC measurements.展开更多
Alpu lignite field is an important coal deposit with nearly 2 billion tons of coal resources located in the middle of Turkey.The mine deposit consists of three main seams.The thickness of two of them vary from 4 to 30...Alpu lignite field is an important coal deposit with nearly 2 billion tons of coal resources located in the middle of Turkey.The mine deposit consists of three main seams.The thickness of two of them vary from 4 to 30 m.The surrounding rock mass is very poor in terms of strength.The high clay content and weak rock mass make mechanized mining difficult.In this research,applicability of the longwall top coal caving method was investigated.The very weak strength behavior of the coal and the surrounding strata increases the importance of research in the mine site in terms of ground control.The aim is to design the mechanized longwall mine based on ground control principles.First of all,classification of the roof,coal,inter-burden,and floor strata were classified based on geotechnical aspects.Then,cavability index,shield,and floor bearing capacity were investigated.Different methods were applied to understand the limitations of a mechanized system that is very critical due to the very low strength strata.According to the main results,roof strata was classified as immediately caving while mining height was calculated as 5-6 m.Finally,the relations among geotechnical characterizations of roof and floor strata,cutting and caving heights,and required shield capacity were presented based on analytical and numerical applications.The proposed approach can be used as a ground control method for the applicability as well as the limitations of mechanized longwall mining design in weak strata conditions.展开更多
基金supported as a primary node of the Australian Research Council Centre of Excellence for Geotechnical Science and Engineering(CE110001009)
文摘Reinstallation of mobile jack-up rigs next to existing footprints is a problematic operation because the spudcan located near the footprints is subjected to eccentric and/or inclined loading conditions. Geotech- nical centrifuge studies have measured these loads for combinations of changing footprint geometry, footprint soil properties and the offset of the reinstallation from the footprint centre. These tests have been of full model spudcans in order to accurately measure the combined loads developed. They have not provided information on the mechanisms of failure occurring during this complex installation. Ob- servations from a visualisation test, where a half spudcan is penetrated against a transparent window in a geotechnical centrifuge, are reported in this paper. The mechanisms of failure at different stages during the nenetrntirm are nr^nted
文摘Geotechnical analyses were carried out to examine the contributions of engineering geological properties of subgrade soils to the failure of the Akure-Ikere Ekiti road,Southwestern Nigeria.Field observations revealed that the road is in a very poor state of serious deformation and disrepair as most parts of the road alignment have failed.The alignment of the studied road is predominantly underlain by Granite,Charnockites,and Migmatites.Laboratory tests results showed that the natural moisture content ranges from 10.98 to 21.4%,liquid limit from 22.8 to 47.7%,plastic limit from 19.2 to 24.6,plasticity index 3.6 to 26.3%.The grain size analysis revealed that the amount of fines ranges from 15.9 to 49%.Others are linear shrinkage,between 1.4 and 10%,free swell between 25 and 46%,maximum dry density from 1593 to 2016 kg/m,and CBR between 5 and 48%.The specific gravity ranges from 2.64 to 2.74.With reference to AASHTO classification,5% of the samples was classified as A-4,15% classified as A-2-4,40% classified as A-6,while 40% classified as A-7-6.The dominance of fair-to-good California bearing ratio,fair to good maximum dry density,high linear shrinkage and A-7-6,A-6,and A-2-4 soil groups have combined to give fair-to-good geotechnical properties to the studied soils.Generally,the fair to good geotechnical properties of soil of the road under study is an indication that the contribution of subgrade soil to the failure of the highway is negligible.The total breakdown of the road can be traced to substandard engineering specifications which are complemented by a poor drainage system.
基金supported by Korea Research Fellowship Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(Grant No.2019H1D3A1A01102993)the Inha University Research Grant(2022).
文摘Ultimate bearing capacity(UBC)is a key subject in geotechnical/foundation engineering as it determines the limit of loads imposed on the foundation.The most reliable means of determining UBC is through experiment,but it is costly and time-consuming which has led to the development of various models based on the simplified assumptions.The outcomes of the models are usually validated with the experimental results,but a large gap usually exists between them.Therefore,a model that can give a close prediction of the experimental results is imperative.This study proposes a grasshopper optimization algorithm(GOA)and salp swarm algorithm(SSA)to optimize artificial neural networks(ANNs)using the existing UBC experimental database.The performances of the proposed models are evaluated using various statistical indices.The obtained results are compared with the existing models.The proposed models outperformed the existing models.The proposed hybrid GOA-ANN and SSA-ANN models are then transformed into mathematical forms that can be incorporated into geotechnical/foundation engineering design codes for accurate UBC measurements.
文摘Alpu lignite field is an important coal deposit with nearly 2 billion tons of coal resources located in the middle of Turkey.The mine deposit consists of three main seams.The thickness of two of them vary from 4 to 30 m.The surrounding rock mass is very poor in terms of strength.The high clay content and weak rock mass make mechanized mining difficult.In this research,applicability of the longwall top coal caving method was investigated.The very weak strength behavior of the coal and the surrounding strata increases the importance of research in the mine site in terms of ground control.The aim is to design the mechanized longwall mine based on ground control principles.First of all,classification of the roof,coal,inter-burden,and floor strata were classified based on geotechnical aspects.Then,cavability index,shield,and floor bearing capacity were investigated.Different methods were applied to understand the limitations of a mechanized system that is very critical due to the very low strength strata.According to the main results,roof strata was classified as immediately caving while mining height was calculated as 5-6 m.Finally,the relations among geotechnical characterizations of roof and floor strata,cutting and caving heights,and required shield capacity were presented based on analytical and numerical applications.The proposed approach can be used as a ground control method for the applicability as well as the limitations of mechanized longwall mining design in weak strata conditions.
