A finite-element analysis considering the anisotropy for the undrained shear strength was performed to examine the effects of the total stress-based anisotropic model NGI-ADP(developed by Norwegian Geotechnical Instit...A finite-element analysis considering the anisotropy for the undrained shear strength was performed to examine the effects of the total stress-based anisotropic model NGI-ADP(developed by Norwegian Geotechnical Institute based on the Active-Direct simple shear-Passive concept)parameters on the base stability of deep braced excavations in clays.These parameters included the ratio of the plane strain passive shear strength to the plane strain active shear strength s_(u)^(P)=s_(u)^(A),the ratio of the unloading/reloading shear modulus to the plane strain active shear strength G_(ur)=s_(u)^(A),the plane strain active shear strength s_(u)^(A),the unit weight c,the excavation width B,the wall thickness b,and the wall penetration depth D.According to the numerical results for 1778 hypothetical cases,extreme gradient boosting(XGBoost)and random forest regression(RFR)were adopted to predict the factor of safety(FS)against basal heave for deep braced excavations.The results indicated that the anisotropic characteristics of soil parameters need to be considered when determining the FS against basal heave for braced excavation.XGBoost and RFR can yield a reasonable prediction of the FS.This paper presents a cuttingedge application of ensemble learning methods in geotechnical engineering.展开更多
The effects of excavation unloading, construction reloading and underground water on basal heave of excavation projects were presented and analyzed based on the measurement results of an underground urban complex whic...The effects of excavation unloading, construction reloading and underground water on basal heave of excavation projects were presented and analyzed based on the measurement results of an underground urban complex which was located in Shanghai. The effects on water pressure and building settlements were analyzed as well. The numerical analyses by finite element method (FEM) were conducted. It showed that the soil under the excavation base continued to heave during the following certain construction stage. It also found that the bearing capacity of uplift piles which supported the buildings affected the structure quality significantly. The conclusions can be applied in future projects.展开更多
基金supported by Chongqing Construction Science and Technology Plan Project(2019-0045)Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJZDK201900102)Chongqing Engineering Research Center of Disaster Prevention and Control for Banks and Structures in Three Gorges Reservoir Area(SXAPGC18YB01,SXAPGC18ZD01).
文摘A finite-element analysis considering the anisotropy for the undrained shear strength was performed to examine the effects of the total stress-based anisotropic model NGI-ADP(developed by Norwegian Geotechnical Institute based on the Active-Direct simple shear-Passive concept)parameters on the base stability of deep braced excavations in clays.These parameters included the ratio of the plane strain passive shear strength to the plane strain active shear strength s_(u)^(P)=s_(u)^(A),the ratio of the unloading/reloading shear modulus to the plane strain active shear strength G_(ur)=s_(u)^(A),the plane strain active shear strength s_(u)^(A),the unit weight c,the excavation width B,the wall thickness b,and the wall penetration depth D.According to the numerical results for 1778 hypothetical cases,extreme gradient boosting(XGBoost)and random forest regression(RFR)were adopted to predict the factor of safety(FS)against basal heave for deep braced excavations.The results indicated that the anisotropic characteristics of soil parameters need to be considered when determining the FS against basal heave for braced excavation.XGBoost and RFR can yield a reasonable prediction of the FS.This paper presents a cuttingedge application of ensemble learning methods in geotechnical engineering.
基金the National Natural Science Foundation of China (No. 50679041)
文摘The effects of excavation unloading, construction reloading and underground water on basal heave of excavation projects were presented and analyzed based on the measurement results of an underground urban complex which was located in Shanghai. The effects on water pressure and building settlements were analyzed as well. The numerical analyses by finite element method (FEM) were conducted. It showed that the soil under the excavation base continued to heave during the following certain construction stage. It also found that the bearing capacity of uplift piles which supported the buildings affected the structure quality significantly. The conclusions can be applied in future projects.
