Establishment of a creep model is an important method to analyze the relationship between soil creep deformation and time,and the element model is widely used for studying soil creep.However,the element creep model is...Establishment of a creep model is an important method to analyze the relationship between soil creep deformation and time,and the element model is widely used for studying soil creep.However,the element creep model is employed for fitting saturated soil,and the mechanical element model is generally linear,which cannot well fit the nonlinear deformation of the soil with time in practice.The creep process of the soil is not only time-dependent,but also related to the deviatoric stress level.Therefore,the fractional calculus theory and a parameter n reflecting the effect of deviatoric stress level on the creep properties of the soil were introduced into the element model,and the fractional qBurgers creep model was established by using the fractional Koeller dashpot and Caputo fractional calculus.The proposed model was used to fit the triaxial test data of reticulated red clay under different net confining pressures and matric suctions by unsaturated triaxial apparatus.The proposed model can well describe the nonlinearity of unsaturated reticulated red clay,has memory and global correlation to the creep development process of unsaturated reticulated red clay,and has clear physical meaning.The functional relationships of the model parameters with the matric suction,net confining pressure and deviatoric stress level were deduced,so that the creep curves of unsaturated reticulated red clay can be obtained for any conditions,which is of great value for the study of unsaturated soils.展开更多
Single-layer reticulated dome structure are commonly high-profile building in the public and can be attractive targets for terrorist bombings,so the public can benefit from enhanced safety with a stronger understandin...Single-layer reticulated dome structure are commonly high-profile building in the public and can be attractive targets for terrorist bombings,so the public can benefit from enhanced safety with a stronger understanding of the behavior of single-layer reticulated dome structure under explosion.This paper investigates the fluid-structure interaction process and the dynamic response performance of the singlelayer reticulated dome under external blast load.Both experimental and numerical results shown that structural deformation is remarkably delayed compared with the velocity of blast wave,which advises the dynamic response of large-span reticulated dome structure has a negligible effect on the blast wave propagation under explosion.Four failure modes are identified by comparing the plastic development of each ring and the residual spatial geometric of the structure,i.e.,minor vibration,local depression,severe damage,and overall collapse.The plastic deformation energy and the displacement potential energy of the structure are the main consumers of the blast energy.In addition,the stress performance of the vertex member and the deep plastic ratio of the whole structure can serve as qualitative indicators to distinguish different failure modes.展开更多
Rainwater harvesting?provides an important alternative source of water in household buildings which?increases water security in urban areas. However, high energy cost consumption by the rainwater harvesting systems re...Rainwater harvesting?provides an important alternative source of water in household buildings which?increases water security in urban areas. However, high energy cost consumption by the rainwater harvesting systems results in higher management costs which may derail the investment viability of these systems in households. This prompted this study to establish ways through which the management cost of rainwater harvesting systems can be minimized in household buildings. A survey of 200 households from Greenspan, Komarock, Utawala, Kileleshwa and Runda in Nairobi?County was undertaken as?well?as?data?on?the?type?of?rainwater harvesting?systems, their operation and maintenance cost collected using observation checklists and questionnaires. The findings indicated that rainwater harvesting typologies 1, 2, 4 and 5 had their water pumped from first-level storage to the second-level storage then supplied to usage points by gravity. Whereas, typologies 3 and 6 had their water moved manually and by gravity respectively. On annual operation cost, 100% of households with typology 3 and 6 spent no money whereas, 100%, 75% and 70.6% with typology 4 and 5, 1 and 2 respectively spent Ksh. 1?-?5000. On annual maintenance cost, 100%, 93.7% and 77.8% of households with typology 5 and 6, 3 and 4 respectively spent Ksh. 1?-?5000 while 25% and 22.2% of households with typology 1 and 2 respectively spent Ksh. 5000?-?10,000. Advanced typology 6 with one-level storage point supplies rainwater to all parts of the household by gravity. This eliminates operation costs spent on energy consumption due to pumping of water,?thus minimizing overall management cost spent on rainwater harvesting systems in household buildings.展开更多
基金supported by the National Science Fund for Distinguished Young Scholars (Grant No.52025085)the National Key Research and Development Program of China (Grant No.2021YFB2600900)the Open Fund of Key Laboratory of Special Environment Road Engineering of Hunan Province,China (Changsha University of Science and Technology) (Grant No.kfj230606).
文摘Establishment of a creep model is an important method to analyze the relationship between soil creep deformation and time,and the element model is widely used for studying soil creep.However,the element creep model is employed for fitting saturated soil,and the mechanical element model is generally linear,which cannot well fit the nonlinear deformation of the soil with time in practice.The creep process of the soil is not only time-dependent,but also related to the deviatoric stress level.Therefore,the fractional calculus theory and a parameter n reflecting the effect of deviatoric stress level on the creep properties of the soil were introduced into the element model,and the fractional qBurgers creep model was established by using the fractional Koeller dashpot and Caputo fractional calculus.The proposed model was used to fit the triaxial test data of reticulated red clay under different net confining pressures and matric suctions by unsaturated triaxial apparatus.The proposed model can well describe the nonlinearity of unsaturated reticulated red clay,has memory and global correlation to the creep development process of unsaturated reticulated red clay,and has clear physical meaning.The functional relationships of the model parameters with the matric suction,net confining pressure and deviatoric stress level were deduced,so that the creep curves of unsaturated reticulated red clay can be obtained for any conditions,which is of great value for the study of unsaturated soils.
基金financial support from the China Postdoctora Science Foundation(project No.2021M690406)financial supports from the National Natural Science Foundation of China(project No.51708521,51778183)。
文摘Single-layer reticulated dome structure are commonly high-profile building in the public and can be attractive targets for terrorist bombings,so the public can benefit from enhanced safety with a stronger understanding of the behavior of single-layer reticulated dome structure under explosion.This paper investigates the fluid-structure interaction process and the dynamic response performance of the singlelayer reticulated dome under external blast load.Both experimental and numerical results shown that structural deformation is remarkably delayed compared with the velocity of blast wave,which advises the dynamic response of large-span reticulated dome structure has a negligible effect on the blast wave propagation under explosion.Four failure modes are identified by comparing the plastic development of each ring and the residual spatial geometric of the structure,i.e.,minor vibration,local depression,severe damage,and overall collapse.The plastic deformation energy and the displacement potential energy of the structure are the main consumers of the blast energy.In addition,the stress performance of the vertex member and the deep plastic ratio of the whole structure can serve as qualitative indicators to distinguish different failure modes.
文摘Rainwater harvesting?provides an important alternative source of water in household buildings which?increases water security in urban areas. However, high energy cost consumption by the rainwater harvesting systems results in higher management costs which may derail the investment viability of these systems in households. This prompted this study to establish ways through which the management cost of rainwater harvesting systems can be minimized in household buildings. A survey of 200 households from Greenspan, Komarock, Utawala, Kileleshwa and Runda in Nairobi?County was undertaken as?well?as?data?on?the?type?of?rainwater harvesting?systems, their operation and maintenance cost collected using observation checklists and questionnaires. The findings indicated that rainwater harvesting typologies 1, 2, 4 and 5 had their water pumped from first-level storage to the second-level storage then supplied to usage points by gravity. Whereas, typologies 3 and 6 had their water moved manually and by gravity respectively. On annual operation cost, 100% of households with typology 3 and 6 spent no money whereas, 100%, 75% and 70.6% with typology 4 and 5, 1 and 2 respectively spent Ksh. 1?-?5000. On annual maintenance cost, 100%, 93.7% and 77.8% of households with typology 5 and 6, 3 and 4 respectively spent Ksh. 1?-?5000 while 25% and 22.2% of households with typology 1 and 2 respectively spent Ksh. 5000?-?10,000. Advanced typology 6 with one-level storage point supplies rainwater to all parts of the household by gravity. This eliminates operation costs spent on energy consumption due to pumping of water,?thus minimizing overall management cost spent on rainwater harvesting systems in household buildings.
