Through the monitoring of mcs-400 mine intrinsically safe anchor cable dynamometer, it is found that after the anchor cable is stretched in place, and the actual displayed data of the dynamometer deviates greatly from...Through the monitoring of mcs-400 mine intrinsically safe anchor cable dynamometer, it is found that after the anchor cable is stretched in place, and the actual displayed data of the dynamometer deviates greatly from the theoretical value, and large prestress loss is caused by factors such as anchor cable relaxation, coal and rock compression creep, water and temperature, dynamic load influence, tunnel friction, group anchor effect and construction quality. The prestress plays a decisive role in the ability of anchor bolt support to control the deformation of surrounding rock. Through detailed cause analysis and test and measurement, the quality of locks and the matching of locks and jacks are determined, which has a serious impact on the prestress loss of anchor cable. And put forward the patent double circuit secondary tension jack of the utility model to further release the mechanical connection between the top anchor pipe (inner ring) of the tension jack and the top presser body (outer ring), and expand the lock ring and lock core of the anchor cable lock twice, which can further eliminate the influence of the matching problem between the lock and the jack top, improve the effective prestress, and ensure the safety and quality of the roof support.展开更多
The load compensation equipment for anchor cable named low retraction prestressed anchorage system with twice-tension(referred to as twice-tension anchorage system) is proposed in the paper. Calculation results of loo...The load compensation equipment for anchor cable named low retraction prestressed anchorage system with twice-tension(referred to as twice-tension anchorage system) is proposed in the paper. Calculation results of loop anchorage prestressing loss(PL) values of inner lining(IL)in Yellow River-crossing tunnel under two anchorage systems,including twice- tension anchorage system and HM(Chinese transliteration is huanmao)anchorage system,are introduced. The software ANSYS is selected to realize the three-dimensional(3D) finite element modeling to accomplish simulation and calculation works under the two anchorage systems,respectively. Stress processes of IL under the two working conditions,of which one is completed cable tensioning(CCT) and the other is water in the tunnel with the designed water pressure(DWP),are contrasted and analyzed. Impacts of prestressing forces of anchor cables on structural safety under the two anchorage systems are contrasted. The calculation results show that the twice-tension anchorage system can reduce PL effectively and then increase prestresses of wall concrete(WC). Meanwhile,the anchorage system has the advantages of improving security and stability of tunnel structure,reducing project costs and saving steel consumption. The research work is available to related design and construction of anchor cable,and is worthy of promotion and application.展开更多
The "Anti-floating Technical Standard for Construction Engineering" (JGJ476-2019) issued by the Ministry of Housing and Urban-rural Development on March 1, 2020 contains specific regulations and requirements...The "Anti-floating Technical Standard for Construction Engineering" (JGJ476-2019) issued by the Ministry of Housing and Urban-rural Development on March 1, 2020 contains specific regulations and requirements for crack control design of anti-floating anchor bolts. Among them, the anti-floating design grade is Grade A, which is designed according to the principle of no cracks, and the anchoring slurry should not generate tensile stress under the standard combination of load effect. The anti-floating design grade is Class B, which is designed according to crack control. The tensile stress in the anchoring slurry should not be greater than the axial tensile strength of the anchoring slurry under the standard combination of load effect. In order to ensure the safety of the design, while achieving the principles of clear and definite theoretical concepts and taking into account of economy, this paper analyzes and discusses the basic concepts, stress process, design principles and methods of the prestressed anti-floating anchor rod, and at the same time gives the matters needing attention and relevant suggestions in the design process.展开更多
Corrosion can significantly impact the safety and stability of the entire structure by reducing the service life and load-bearing capacity of anchors.This study provides an in-depth examination of the effects of corro...Corrosion can significantly impact the safety and stability of the entire structure by reducing the service life and load-bearing capacity of anchors.This study provides an in-depth examination of the effects of corrosion on prestressed anchor cables,covering the effects on the anchor cables themselves and the bond interface.The force characteristics and load transfer mechanisms within the anchorage structure were explored through a detailed analysis of the three key components:the anchor cable,the grout,and the surrounding rock.The distribution functions of axial force and interfacial shear stress considering the debonding of the anchor-grout interface were derived,and the prestressed corrosion damage model was further developed.Taking the anchoring project on the slopes in Nagasaki as an example,the stress distribution of anchor cables under different surrounding rock conditions was analyzed in depth.The results showed that the relative deformation of the grout and the surrounding rock decreases when the elasticity modulus of the surrounding rock increases,resulting in a reduced axial force in anchor cables and an increased interface shear stress.Thresholds exist for the effect of the total anchor length and radius on prestressing stability.When designing anchor structures in corrosive environments,there is no need to choose excessive anchor length or anchor radius to achieve better cost-effectiveness.In practical underground engineering,the force in anchor cables is transferred to the surrounding rock through the anchoring section,where the length of the anchorage section has a more direct impact on prestress transfer and stability.展开更多
文摘Through the monitoring of mcs-400 mine intrinsically safe anchor cable dynamometer, it is found that after the anchor cable is stretched in place, and the actual displayed data of the dynamometer deviates greatly from the theoretical value, and large prestress loss is caused by factors such as anchor cable relaxation, coal and rock compression creep, water and temperature, dynamic load influence, tunnel friction, group anchor effect and construction quality. The prestress plays a decisive role in the ability of anchor bolt support to control the deformation of surrounding rock. Through detailed cause analysis and test and measurement, the quality of locks and the matching of locks and jacks are determined, which has a serious impact on the prestress loss of anchor cable. And put forward the patent double circuit secondary tension jack of the utility model to further release the mechanical connection between the top anchor pipe (inner ring) of the tension jack and the top presser body (outer ring), and expand the lock ring and lock core of the anchor cable lock twice, which can further eliminate the influence of the matching problem between the lock and the jack top, improve the effective prestress, and ensure the safety and quality of the roof support.
基金National Natural Science Foundation of China(No.51079107)Fundamental Research Funds for the Central Universities(No.5082022)
文摘The load compensation equipment for anchor cable named low retraction prestressed anchorage system with twice-tension(referred to as twice-tension anchorage system) is proposed in the paper. Calculation results of loop anchorage prestressing loss(PL) values of inner lining(IL)in Yellow River-crossing tunnel under two anchorage systems,including twice- tension anchorage system and HM(Chinese transliteration is huanmao)anchorage system,are introduced. The software ANSYS is selected to realize the three-dimensional(3D) finite element modeling to accomplish simulation and calculation works under the two anchorage systems,respectively. Stress processes of IL under the two working conditions,of which one is completed cable tensioning(CCT) and the other is water in the tunnel with the designed water pressure(DWP),are contrasted and analyzed. Impacts of prestressing forces of anchor cables on structural safety under the two anchorage systems are contrasted. The calculation results show that the twice-tension anchorage system can reduce PL effectively and then increase prestresses of wall concrete(WC). Meanwhile,the anchorage system has the advantages of improving security and stability of tunnel structure,reducing project costs and saving steel consumption. The research work is available to related design and construction of anchor cable,and is worthy of promotion and application.
文摘The "Anti-floating Technical Standard for Construction Engineering" (JGJ476-2019) issued by the Ministry of Housing and Urban-rural Development on March 1, 2020 contains specific regulations and requirements for crack control design of anti-floating anchor bolts. Among them, the anti-floating design grade is Grade A, which is designed according to the principle of no cracks, and the anchoring slurry should not generate tensile stress under the standard combination of load effect. The anti-floating design grade is Class B, which is designed according to crack control. The tensile stress in the anchoring slurry should not be greater than the axial tensile strength of the anchoring slurry under the standard combination of load effect. In order to ensure the safety of the design, while achieving the principles of clear and definite theoretical concepts and taking into account of economy, this paper analyzes and discusses the basic concepts, stress process, design principles and methods of the prestressed anti-floating anchor rod, and at the same time gives the matters needing attention and relevant suggestions in the design process.
基金funded by the National Key Research and Development Program Young Scientist Project(2024YFC2911000)State Scholarship Fund of China(No.202306650001).
文摘Corrosion can significantly impact the safety and stability of the entire structure by reducing the service life and load-bearing capacity of anchors.This study provides an in-depth examination of the effects of corrosion on prestressed anchor cables,covering the effects on the anchor cables themselves and the bond interface.The force characteristics and load transfer mechanisms within the anchorage structure were explored through a detailed analysis of the three key components:the anchor cable,the grout,and the surrounding rock.The distribution functions of axial force and interfacial shear stress considering the debonding of the anchor-grout interface were derived,and the prestressed corrosion damage model was further developed.Taking the anchoring project on the slopes in Nagasaki as an example,the stress distribution of anchor cables under different surrounding rock conditions was analyzed in depth.The results showed that the relative deformation of the grout and the surrounding rock decreases when the elasticity modulus of the surrounding rock increases,resulting in a reduced axial force in anchor cables and an increased interface shear stress.Thresholds exist for the effect of the total anchor length and radius on prestressing stability.When designing anchor structures in corrosive environments,there is no need to choose excessive anchor length or anchor radius to achieve better cost-effectiveness.In practical underground engineering,the force in anchor cables is transferred to the surrounding rock through the anchoring section,where the length of the anchorage section has a more direct impact on prestress transfer and stability.
