To investigate the seismic performance of the double-row pre-stressed anchor piles （DRPAPs） on the Yuxi-Mengzi railway, FLAC3D was used to construct a three-dimensional model. Using Koyna earthquake records as input...To investigate the seismic performance of the double-row pre-stressed anchor piles （DRPAPs） on the Yuxi-Mengzi railway, FLAC3D was used to construct a three-dimensional model. Using Koyna earthquake records as input motions, dynamic time-history analyses were carried out. In the analyses, we compared earth pressure on the front and back of the piles and deformation of the piles under different seismic forces with or without anchor cables. With the anchor cable present, the earth pressure on the back of the pile＇s free section increases, but that on the back of the pile＇s anchorage section decreases. Also, with anchor cables, the earth pressure on the front of the upper pile decreases, and that on the back of the lower pile decreases.展开更多
With resource exploitation and engineering construction gradually going deeper,the surrounding rock dynamic disaster becomes frequent and violent.The anchorage support is a common control method of surrounding rock in...With resource exploitation and engineering construction gradually going deeper,the surrounding rock dynamic disaster becomes frequent and violent.The anchorage support is a common control method of surrounding rock in underground engineering.To study the dynamic damage characteristics of anchored rock and the energy absorption control mechanism of dynamic disasters,a new type of constant resistance and energy absorption(CREA)material with high strength,high elongation and high energy absorption characteristics is developed.A contrast test of rockbursts in anchored rock with different support materials is conducted.The test results show that the surface damage rates and energy release degree of anchored rock with common bolt(CB)and CREA are lower than those of unanchored rock,respectively.The total energy,average energy and maximum energy released by CREA anchored rock are 30.9%,94.3%and 84.4%lower than those of CB anchored rock.Compared with unanchored rock,the rockburst peak stress in the CREA anchored rock is increased by 39.9%,and the rockburst time is delayed by 53.2%.Based on the rockburst energy calculation model,the evolution law of rockburst peak stress and energy release is investigated.The control mechanism of CREA support units on rock dynamic failure is clarified.展开更多
The anchoring capacity of the anchor cable is closely related to the bonding length and radial pressure conditions.Through field pull-out tests,theoretical analysis,numerical simulation,and industrial tests,this study...The anchoring capacity of the anchor cable is closely related to the bonding length and radial pressure conditions.Through field pull-out tests,theoretical analysis,numerical simulation,and industrial tests,this study clarifies the relationship between radial pressure and bonding length for the ultimate pullout force and reveals the microscopic failure process of the resin-rock interface in the anchoring system.The results show that the ultimate load increases with the increase of bonding length in three different stages:rapid,slow,and uniform growth.The new mechanical model developed considering radial pressure describes the inverse relationship between radial pressure and the plastic zone on the bonding section,and quantifies the reinforcing effect of confining pressure on the anchoring force.During the pull-out process of the anchor cable,the generation of failure cracks is in the order of orifice,bottom,and middle of the hole.Radial pressure can effectively enhance the ultimate pull-out force,alleviate the oscillation increase of pull-out force,and inhibit resin cracking,but will produce an external crushing zone.It also reveals the synergistic effect between bonding length and radial pressure,and successfully carries out industrial tests of anchor cable support,which ensures the stability of the stope roof and provides an important reference for the design of anchor cable support in deep high-stress mines.展开更多
To elucidate the yielding performance of compact yielding anchor cables in working state,a yielding mechanical model incorporating extrusion friction and fastening rotation under confining pressure is constructed.The ...To elucidate the yielding performance of compact yielding anchor cables in working state,a yielding mechanical model incorporating extrusion friction and fastening rotation under confining pressure is constructed.The yielding resistance enhancement effect(ω)caused by working environment constraints is evaluated through multi-layer composite sleeve hole expansion analysis,forming a theoretical framework for calculating the working yielding force.Laboratory and in-situ pull-out tests are conducted to determine the yielding performance and validate the analytical theory.The main conclusions are:(1)Yielding force and energy-release capacity increase withω,significantly outperforming the unconfined state.(2)In-situ tests under varying rockmass and geostress conditions(F1–F3)determine the yielding force increases to 183.4–290.1,204.0–290.8,and 235.0–327.1 kN.(3)The slight deviation(–12.5%to 6.2%)between the theoretical and measured yielding force confirms that the analytical theory effectively describes the working yielding performance.(4)ωincreases with higher geostress and improved rock mechanical properties,with initial geostress(σ_(0))and elastic modulus of surrounding rock(E_(3))identified as critical parameters.展开更多
Feasibility of using pre-stressed carbon fiber plates to strengthen reinforced concrete beams was studied. Based on the characteristics of carbon fiber plates, we developed a pre-stress clamp and a device for applying...Feasibility of using pre-stressed carbon fiber plates to strengthen reinforced concrete beams was studied. Based on the characteristics of carbon fiber plates, we developed a pre-stress clamp and a device for applying the pre-stress. Contrast tests were conducted between ordinary carbon fiber plates and a pre-stressed carbon fiber plate and between secondary loaded carbon fiber plates and a concrete beam strengthened with a secondary loaded carbon fiber plate. On this basis, we analyzed the failure pattern, the width of cracks and their distribution, the cracking load, the yield load, the limit load and the relation between load and deflec- tion. The results indicate that using pre-stressed carbon fiber plates to strengthen concrete beams is feasible and effective.展开更多
The application of ductile rock bolts has been a crucial method for solving the problems of large deformations,energy absorption and stability control issues in deep rock masses.To study the anchoring mechanism of the...The application of ductile rock bolts has been a crucial method for solving the problems of large deformations,energy absorption and stability control issues in deep rock masses.To study the anchoring mechanism of the key expansive structure,this paper proposes a novel type of bolt—the Ductile-Expansion bolt,and conducts research on anchoring mechanics,energy absorption characteristics,and failure modes of the bolt.In addition,this paper defines the concept of load-volume ratio of metal rock bolts and proves the Ductile-Expansion bolt is capable of better improving the unit volume bearing capacity of the bolt material.Furthermore,laboratory and field tests verify the Ductile-Expansion bolt had better anchoring effect than the traditional rebar bolt,with the expansion structure favorably enhancing the ductility and energy absorption performance of the bolt.Finally,this paper microscopically analyzes the crack propagation and distribution morphology of the bolts by establishing a 3D coupled numerical model based on FDM-DEM.Numerical results illustrate the interface at the variable diameter of the Ductile-Expansion bolt serves as the transition zone between high and low stress levels.The expansion structure can impose radial compression on the medium around the bolt,which can improve the bolt anchorage performance.展开更多
Cyclic impact induces ongoing fatigue damage and performance degradation in anchoring structures,ser-ving as a critical factor leading to the instability of deep roadways.This paper takes the intrinsic spatio-temporal...Cyclic impact induces ongoing fatigue damage and performance degradation in anchoring structures,ser-ving as a critical factor leading to the instability of deep roadways.This paper takes the intrinsic spatio-temporal relationship of macro-microscopic cumulative damage in anchoring structures as the main thread,revealing the mechanism of bearing capacity degradation and progressive instability of anchoring structure under cyclic impact.Firstly,a set of impact test devices and methods for the prestressed solid anchor bolt anchoring structure were developed,effectively replicating the cyclic impact stress paths in situ.Secondly,cyclic impact anchoring structure tests and simulations were conducted,which clarifies the damage evolution mechanism of the anchoring structure.Prestress loss follows a cubic decay func-tion as the number of impacts increases.Under the same impact energy and pretension force,the impact resistance cycles of extended anchoring and full-length anchoring were increased by 186.7%and 280%,respectively,compared to end anchoring.The rate of internal damage accumulation is positively corre-lated with impact energy and negatively correlated with anchorage length.Internal tensile cracks account for approximately 85%.Stress transmission follows a fluctuating pattern.Compared to the extended anchoring,the maximum vibration velocity of the exposed end particles in the full-length anchoring was reduced by 59.31%.Damage evolution exhibits a pronounced cumulative mutation effect.Then,a three-media,two-interface mechanical model of the anchoring structure was constructed.It has been clarified that the compressive stress,tensile stress,and oscillation effect arising from rapid transi-tions between compression and tension are the primary internal factors responsible for the degradation of the anchoring structure’s bearing capacity.Finally,the progressive instability mechanism of the anchoring structure under cyclic impact was elucidated.The mutual feedback and superposition of media rupture,interface debonding,and bearing capacity degradation result in overall failure.The failure pro-cess involves stages dominated by oscillation-compression,tensile stress,and compression failure.A tar-geted control strategy was further proposed.This provides a reference for maintaining the long-term stability of deep roadways under dynamic impact loads.展开更多
Excavating super-large-span tunnels in soft rock masses presents significant challenges.To ensure safety,the sequential excavation method is commonly adopted.It utilizes internal temporary supports to spatially partit...Excavating super-large-span tunnels in soft rock masses presents significant challenges.To ensure safety,the sequential excavation method is commonly adopted.It utilizes internal temporary supports to spatially partition the tunnel face and divide the excavation into multiple stages.However,these internal supports generally impose spatial constraints,limiting the use of large-scale excavation equipment and reducing construction efficiency.To address this constraint,this study adopts the“Shed-frame”principle to explore the feasibility of an innovative support system,which aims to replace internal supports with prestressed anchor cables and thus provide a more spacious working space with fewer internal obstructions.To evaluate its effectiveness,a field case involving the excavation of a 24-m span tunnel in soft rock is presented,and an analysis of extensive field data is conducted to study the deformation characteristics of the surrounding rock and the mechanical behavior of the support system.The results revealed that prestressed anchor cables integrated the initial support with the shed,creating an effective“shed-frame”system,which successively maintained tunnel deformation and frame stress levels within safe regulatory bounds.Moreover,the prestressed anchor cables bolstered the surrounding rock effectively and reduced the excavation-induced disturbance zone significantly.In summary,the proposed support system balances construction efficiency and safety.These field experiences may offer valuable insights into the popularization and further development of prestressed anchor cable support systems.展开更多
文摘To investigate the seismic performance of the double-row pre-stressed anchor piles （DRPAPs） on the Yuxi-Mengzi railway, FLAC3D was used to construct a three-dimensional model. Using Koyna earthquake records as input motions, dynamic time-history analyses were carried out. In the analyses, we compared earth pressure on the front and back of the piles and deformation of the piles under different seismic forces with or without anchor cables. With the anchor cable present, the earth pressure on the back of the pile＇s free section increases, but that on the back of the pile＇s anchorage section decreases. Also, with anchor cables, the earth pressure on the front of the upper pile decreases, and that on the back of the lower pile decreases.
基金supported by the National Key Research and Development Program of China(No.2023YFC2907600)the National Natural Science Foundation of China(Nos.42477166 and 42277174)+2 种基金the Fundamental Research Funds for the Central Universities,China(No.2024JCCXSB01)the Opening Project of State Key Laboratory of Explosion Science and Safety Protection,Beijing Institute of Technology(No.KFJJ24-01M)the Open Foundation of Collaborative Innovation Center of Green Development and Ecological Restoration of Mineral Resources(No.HLCX2024-04)。
文摘With resource exploitation and engineering construction gradually going deeper,the surrounding rock dynamic disaster becomes frequent and violent.The anchorage support is a common control method of surrounding rock in underground engineering.To study the dynamic damage characteristics of anchored rock and the energy absorption control mechanism of dynamic disasters,a new type of constant resistance and energy absorption(CREA)material with high strength,high elongation and high energy absorption characteristics is developed.A contrast test of rockbursts in anchored rock with different support materials is conducted.The test results show that the surface damage rates and energy release degree of anchored rock with common bolt(CB)and CREA are lower than those of unanchored rock,respectively.The total energy,average energy and maximum energy released by CREA anchored rock are 30.9%,94.3%and 84.4%lower than those of CB anchored rock.Compared with unanchored rock,the rockburst peak stress in the CREA anchored rock is increased by 39.9%,and the rockburst time is delayed by 53.2%.Based on the rockburst energy calculation model,the evolution law of rockburst peak stress and energy release is investigated.The control mechanism of CREA support units on rock dynamic failure is clarified.
基金Financial supports for this work,provided by the National Natural Science Foundation Project of China(No.52374152)the Guangxi Science and Technology Plan Project of China(No.2022AB31023)the National Basic Research Development Program of China(No.2022YFC2904602)are gratefully acknowledged。
文摘The anchoring capacity of the anchor cable is closely related to the bonding length and radial pressure conditions.Through field pull-out tests,theoretical analysis,numerical simulation,and industrial tests,this study clarifies the relationship between radial pressure and bonding length for the ultimate pullout force and reveals the microscopic failure process of the resin-rock interface in the anchoring system.The results show that the ultimate load increases with the increase of bonding length in three different stages:rapid,slow,and uniform growth.The new mechanical model developed considering radial pressure describes the inverse relationship between radial pressure and the plastic zone on the bonding section,and quantifies the reinforcing effect of confining pressure on the anchoring force.During the pull-out process of the anchor cable,the generation of failure cracks is in the order of orifice,bottom,and middle of the hole.Radial pressure can effectively enhance the ultimate pull-out force,alleviate the oscillation increase of pull-out force,and inhibit resin cracking,but will produce an external crushing zone.It also reveals the synergistic effect between bonding length and radial pressure,and successfully carries out industrial tests of anchor cable support,which ensures the stability of the stope roof and provides an important reference for the design of anchor cable support in deep high-stress mines.
基金supported by the National Natural Science Foundation of China(Nos.U2468217,U2034205,and 52308391)。
文摘To elucidate the yielding performance of compact yielding anchor cables in working state,a yielding mechanical model incorporating extrusion friction and fastening rotation under confining pressure is constructed.The yielding resistance enhancement effect(ω)caused by working environment constraints is evaluated through multi-layer composite sleeve hole expansion analysis,forming a theoretical framework for calculating the working yielding force.Laboratory and in-situ pull-out tests are conducted to determine the yielding performance and validate the analytical theory.The main conclusions are:(1)Yielding force and energy-release capacity increase withω,significantly outperforming the unconfined state.(2)In-situ tests under varying rockmass and geostress conditions(F1–F3)determine the yielding force increases to 183.4–290.1,204.0–290.8,and 235.0–327.1 kN.(3)The slight deviation(–12.5%to 6.2%)between the theoretical and measured yielding force confirms that the analytical theory effectively describes the working yielding performance.(4)ωincreases with higher geostress and improved rock mechanical properties,with initial geostress(σ_(0))and elastic modulus of surrounding rock(E_(3))identified as critical parameters.
文摘Feasibility of using pre-stressed carbon fiber plates to strengthen reinforced concrete beams was studied. Based on the characteristics of carbon fiber plates, we developed a pre-stress clamp and a device for applying the pre-stress. Contrast tests were conducted between ordinary carbon fiber plates and a pre-stressed carbon fiber plate and between secondary loaded carbon fiber plates and a concrete beam strengthened with a secondary loaded carbon fiber plate. On this basis, we analyzed the failure pattern, the width of cracks and their distribution, the cracking load, the yield load, the limit load and the relation between load and deflec- tion. The results indicate that using pre-stressed carbon fiber plates to strengthen concrete beams is feasible and effective.
基金supported by the National Natural Science Foundation of China(Nos.52174101,52474169,and 42477202)Guangdong Basic and Applied Basic Research Foundation(Nos.2023A1515011634 and 2023A1515030243)the Department of Science and Technology of Guangdong Province,China(No.2021ZT09G087).
文摘The application of ductile rock bolts has been a crucial method for solving the problems of large deformations,energy absorption and stability control issues in deep rock masses.To study the anchoring mechanism of the key expansive structure,this paper proposes a novel type of bolt—the Ductile-Expansion bolt,and conducts research on anchoring mechanics,energy absorption characteristics,and failure modes of the bolt.In addition,this paper defines the concept of load-volume ratio of metal rock bolts and proves the Ductile-Expansion bolt is capable of better improving the unit volume bearing capacity of the bolt material.Furthermore,laboratory and field tests verify the Ductile-Expansion bolt had better anchoring effect than the traditional rebar bolt,with the expansion structure favorably enhancing the ductility and energy absorption performance of the bolt.Finally,this paper microscopically analyzes the crack propagation and distribution morphology of the bolts by establishing a 3D coupled numerical model based on FDM-DEM.Numerical results illustrate the interface at the variable diameter of the Ductile-Expansion bolt serves as the transition zone between high and low stress levels.The expansion structure can impose radial compression on the medium around the bolt,which can improve the bolt anchorage performance.
基金supported by National Key Research and Development Program of China(No.2023YFC2907600)the National Natural Science Foundation of China(Nos.52074263,52274145 and 52034007)+1 种基金the Postdoctoral Fellowship Program(Grade C)of China Postdoctoral Science Foundation(No.GZC20241925)the Fundamental Research Funds for the Central Universities(No.2024QN11002).
文摘Cyclic impact induces ongoing fatigue damage and performance degradation in anchoring structures,ser-ving as a critical factor leading to the instability of deep roadways.This paper takes the intrinsic spatio-temporal relationship of macro-microscopic cumulative damage in anchoring structures as the main thread,revealing the mechanism of bearing capacity degradation and progressive instability of anchoring structure under cyclic impact.Firstly,a set of impact test devices and methods for the prestressed solid anchor bolt anchoring structure were developed,effectively replicating the cyclic impact stress paths in situ.Secondly,cyclic impact anchoring structure tests and simulations were conducted,which clarifies the damage evolution mechanism of the anchoring structure.Prestress loss follows a cubic decay func-tion as the number of impacts increases.Under the same impact energy and pretension force,the impact resistance cycles of extended anchoring and full-length anchoring were increased by 186.7%and 280%,respectively,compared to end anchoring.The rate of internal damage accumulation is positively corre-lated with impact energy and negatively correlated with anchorage length.Internal tensile cracks account for approximately 85%.Stress transmission follows a fluctuating pattern.Compared to the extended anchoring,the maximum vibration velocity of the exposed end particles in the full-length anchoring was reduced by 59.31%.Damage evolution exhibits a pronounced cumulative mutation effect.Then,a three-media,two-interface mechanical model of the anchoring structure was constructed.It has been clarified that the compressive stress,tensile stress,and oscillation effect arising from rapid transi-tions between compression and tension are the primary internal factors responsible for the degradation of the anchoring structure’s bearing capacity.Finally,the progressive instability mechanism of the anchoring structure under cyclic impact was elucidated.The mutual feedback and superposition of media rupture,interface debonding,and bearing capacity degradation result in overall failure.The failure pro-cess involves stages dominated by oscillation-compression,tensile stress,and compression failure.A tar-geted control strategy was further proposed.This provides a reference for maintaining the long-term stability of deep roadways under dynamic impact loads.
基金supported by the National Natural Science Foundation of China through Grant No.51978523.
文摘Excavating super-large-span tunnels in soft rock masses presents significant challenges.To ensure safety,the sequential excavation method is commonly adopted.It utilizes internal temporary supports to spatially partition the tunnel face and divide the excavation into multiple stages.However,these internal supports generally impose spatial constraints,limiting the use of large-scale excavation equipment and reducing construction efficiency.To address this constraint,this study adopts the“Shed-frame”principle to explore the feasibility of an innovative support system,which aims to replace internal supports with prestressed anchor cables and thus provide a more spacious working space with fewer internal obstructions.To evaluate its effectiveness,a field case involving the excavation of a 24-m span tunnel in soft rock is presented,and an analysis of extensive field data is conducted to study the deformation characteristics of the surrounding rock and the mechanical behavior of the support system.The results revealed that prestressed anchor cables integrated the initial support with the shed,creating an effective“shed-frame”system,which successively maintained tunnel deformation and frame stress levels within safe regulatory bounds.Moreover,the prestressed anchor cables bolstered the surrounding rock effectively and reduced the excavation-induced disturbance zone significantly.In summary,the proposed support system balances construction efficiency and safety.These field experiences may offer valuable insights into the popularization and further development of prestressed anchor cable support systems.
