The addition of basement beneath existing building changes the underpinning pile from fully embedded to partially embedded,and thus influences the mechanical properties of pile.In the past,scholars paid attention to t...The addition of basement beneath existing building changes the underpinning pile from fully embedded to partially embedded,and thus influences the mechanical properties of pile.In the past,scholars paid attention to the change in the bearing capacity of pile but neglected the difference of dynamic characteristics before and after construction,and potential changes in stress history of remaining soil are also ignored.In this work,a calculation model is built to investigate the influence of excavation on dynamic impedance of underpinning pile considering the effect of stress history.The soil is simulated by the dynamic Winkler foundation,which is characterized by springs and dashpots.Properties of remaining soil after excavation are updated to consider the effect of stress history through modifying the initial shear modulus and related parameters.The dynamic impedance of pile after excavation is obtained based on the transfer matrix method.The parameter study is carried out to evaluate the dynamic impedance with various excavation depths,considering or ignoring stress history effect,and various element lengths.The results show that shallow soil plays an important role to dynamic impedance,and overestimated dynamic impedance is obtained if not considering the stress history effect.展开更多
Adequate regional groundwater assessment studies are essential for the correct groundwater management by policy/decision makers; increased use of groundwater resources and drought have led to concern about the future ...Adequate regional groundwater assessment studies are essential for the correct groundwater management by policy/decision makers; increased use of groundwater resources and drought have led to concern about the future availability of groundwater to meet domestic, agricultural, industrial, and environmental needs. Deep understanding of spatial and temporal water table dynamics together with transport processes is required. This paper gathers historical geological, hidrological and chemical information for quantitative and qualitative as well as spatial and temporal evolution of groundwater for Aguanaval and Chupaderos aquifers, both surrounding Calera aquifer in Mexico. Historical databases were employed to determine temporal trends of water levels and values were projected for years 2010, 2030 and 2050. Potential recharge sites were also identified through water level-topography correlation. The water quality analysis was completed by obtaining, through geostatistics, spatial distributions for bicarbonate, chloride, sulfate, total dissolved solids, temperature, and sodium, employing databases generated in recent sampling campaigns. This analysis provided additional elements to help understand the functioning of groundwater in studied aquifers. Finally, results were compared with permissible values established in the Mexican norm.展开更多
基金Projects(51878487,41672266)supported by the National Natural Science Foundation of China。
文摘The addition of basement beneath existing building changes the underpinning pile from fully embedded to partially embedded,and thus influences the mechanical properties of pile.In the past,scholars paid attention to the change in the bearing capacity of pile but neglected the difference of dynamic characteristics before and after construction,and potential changes in stress history of remaining soil are also ignored.In this work,a calculation model is built to investigate the influence of excavation on dynamic impedance of underpinning pile considering the effect of stress history.The soil is simulated by the dynamic Winkler foundation,which is characterized by springs and dashpots.Properties of remaining soil after excavation are updated to consider the effect of stress history through modifying the initial shear modulus and related parameters.The dynamic impedance of pile after excavation is obtained based on the transfer matrix method.The parameter study is carried out to evaluate the dynamic impedance with various excavation depths,considering or ignoring stress history effect,and various element lengths.The results show that shallow soil plays an important role to dynamic impedance,and overestimated dynamic impedance is obtained if not considering the stress history effect.
文摘Adequate regional groundwater assessment studies are essential for the correct groundwater management by policy/decision makers; increased use of groundwater resources and drought have led to concern about the future availability of groundwater to meet domestic, agricultural, industrial, and environmental needs. Deep understanding of spatial and temporal water table dynamics together with transport processes is required. This paper gathers historical geological, hidrological and chemical information for quantitative and qualitative as well as spatial and temporal evolution of groundwater for Aguanaval and Chupaderos aquifers, both surrounding Calera aquifer in Mexico. Historical databases were employed to determine temporal trends of water levels and values were projected for years 2010, 2030 and 2050. Potential recharge sites were also identified through water level-topography correlation. The water quality analysis was completed by obtaining, through geostatistics, spatial distributions for bicarbonate, chloride, sulfate, total dissolved solids, temperature, and sodium, employing databases generated in recent sampling campaigns. This analysis provided additional elements to help understand the functioning of groundwater in studied aquifers. Finally, results were compared with permissible values established in the Mexican norm.
