The anchor stress extent of a prestress anchor cable project has a direct relation with the project safety and performance. Prestressed tensioning method is a kind of nondestructive testing method, by which a reverse ...The anchor stress extent of a prestress anchor cable project has a direct relation with the project safety and performance. Prestressed tensioning method is a kind of nondestructive testing method, by which a reverse stretching load is applied on the external exposure section of anchor cable under construction or in service, and then the elongation variation of stress bars is measured to determine the anchor stress. We elaborated the theory and testing mechanism of prestressed tensioning method, and systematically studied key issues during the prestressed tensioning process of anchor cable by using physical model test, including the composition of tension stress-elongation curve, the variation of anchor stress, the compensation of locked anchor stress, and the judgment of anchor stress, and verified the theory feasibility of prestressed tensioning method. A case study on slope anchor cable of one highway project was conducted to further discuss on the test method, operation procedures and judgment of prestressed tensioning method on obtaining anchor stress, and then the test data of three situations were analyzed. The result provides a theoretical basis and technical base for the application of prestressed tensioning method to the evaluation of construction quality and operation conditions of anchor cable project.展开更多
The load transfer characteristics of a tensile anchor in the rock mass with weak interlayers were investigated,considering the nonuniform stress of the horizontally layered rock mass along anchors.An improved shear-sl...The load transfer characteristics of a tensile anchor in the rock mass with weak interlayers were investigated,considering the nonuniform stress of the horizontally layered rock mass along anchors.An improved shear-slipping model was proposed to describe the stress evolution characteristics of the bolt-rock interface.Based on the improved model,analytical solutions of the axial force,shear stress distribution and load-displacement relationship considering the residual stress stage were established.The effects of the stratigraphic sequence,pulling force and bolt diameter on the stress distribution of the anchorage interface were evaluated by using analytical solutions.The results were verified by applying the finite difference numerical simulation method.The sensitivity of each parameter to the axial force and shear stress of the rock bolt was determined based on calculation of the sensitivity coefficient.The study results show that the axial force and shear stress tend to decrease nonuniformly along the rock bolt towards the anchorage depth.Due to the existence of weak interlayers,the shear stress mutates at the weak and hard rock interface,and the axial force appears to“rebound”at the bottom of the anchored section.Lithology has more significant effects on the axial force and shear stress at the bottom of the anchor than at the top of the anchor.The pulling force is more sensitive to the anchor stress than stratigraphic sequence when the bolt diameter is determined.This study provides a theoretical framework for the fundamental problem of tensile bolts in horizontally or vertically laminated rock masses,providing a theoretical basis for anchor design.展开更多
基金Funded by the Science and Technolog Program of Ministry of Transport of P.R.China(No.2012318352100)
文摘The anchor stress extent of a prestress anchor cable project has a direct relation with the project safety and performance. Prestressed tensioning method is a kind of nondestructive testing method, by which a reverse stretching load is applied on the external exposure section of anchor cable under construction or in service, and then the elongation variation of stress bars is measured to determine the anchor stress. We elaborated the theory and testing mechanism of prestressed tensioning method, and systematically studied key issues during the prestressed tensioning process of anchor cable by using physical model test, including the composition of tension stress-elongation curve, the variation of anchor stress, the compensation of locked anchor stress, and the judgment of anchor stress, and verified the theory feasibility of prestressed tensioning method. A case study on slope anchor cable of one highway project was conducted to further discuss on the test method, operation procedures and judgment of prestressed tensioning method on obtaining anchor stress, and then the test data of three situations were analyzed. The result provides a theoretical basis and technical base for the application of prestressed tensioning method to the evaluation of construction quality and operation conditions of anchor cable project.
基金supported by the National Key R&D Program of China(Nos.2018YFC1505300,2017YFC1501304)National Natural Science Foundation of China(Grout Nos.42090054,41922055 and 41931295)+2 种基金the Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)(No.CUGGC09)Research Project of China Three Gorges Corporation(No.2019073)the Zhejiang Huadong Construction Engineering Co.,Ltd.(No.KY2019-HDJS-07)。
文摘The load transfer characteristics of a tensile anchor in the rock mass with weak interlayers were investigated,considering the nonuniform stress of the horizontally layered rock mass along anchors.An improved shear-slipping model was proposed to describe the stress evolution characteristics of the bolt-rock interface.Based on the improved model,analytical solutions of the axial force,shear stress distribution and load-displacement relationship considering the residual stress stage were established.The effects of the stratigraphic sequence,pulling force and bolt diameter on the stress distribution of the anchorage interface were evaluated by using analytical solutions.The results were verified by applying the finite difference numerical simulation method.The sensitivity of each parameter to the axial force and shear stress of the rock bolt was determined based on calculation of the sensitivity coefficient.The study results show that the axial force and shear stress tend to decrease nonuniformly along the rock bolt towards the anchorage depth.Due to the existence of weak interlayers,the shear stress mutates at the weak and hard rock interface,and the axial force appears to“rebound”at the bottom of the anchored section.Lithology has more significant effects on the axial force and shear stress at the bottom of the anchor than at the top of the anchor.The pulling force is more sensitive to the anchor stress than stratigraphic sequence when the bolt diameter is determined.This study provides a theoretical framework for the fundamental problem of tensile bolts in horizontally or vertically laminated rock masses,providing a theoretical basis for anchor design.
