In geotechnical engineering,rock bolts are commonly used for reinforcement,while the surrounding rock mass bears varying degrees of shear loads.The shear rate affects the stability of bolted rock joints,especially in ...In geotechnical engineering,rock bolts are commonly used for reinforcement,while the surrounding rock mass bears varying degrees of shear loads.The shear rate affects the stability of bolted rock joints,especially in projects susceptible to dynamic shear loads.In laboratory experiments,fully-grouted bolts and energy-absorbing bolts were used as research objects,and artificial rock specimens with rough joints were fabricated to analyze the shear characteristics and damage mechanisms of bolted rock joints under cyclic shear conditions and different shear velocities.The results showed that as the shear rate increased,the shear strength of bolted rock joint specimens decreased.Degradation of asperities resulted in no obvious peak shear stress in the specimens.Energy-absorbing bolts exhibited greater deformation capacity,with significant necking phenomena and the ability to withstand larger shear displacements.In contrast,fully-grouted bolts,which have threaded surfaces that provide higher bonding performance,exhibited a reduced capacity for plastic deformation and were prone to breaking under smaller shear displacements.Although the shear stiffness of specimens reinforced by energy-absorbing bolts was slightly lower than that of fully-grouted bolt specimens,they demonstrated greater stability under various shear rates.The absorbed shear energy showed that energy-absorbing bolts had superior coordinated deformation capabilities,thus exhibiting greater absorbed shear energy than fully-grouted bolts.Overall,fully-grouted bolts are more suitable for projects requiring higher rock shear strength and overall stiffness.In contrast,energy-absorbing bolts are more suitable for coping with dynamic or fluctuating load conditions to maintain the relative stability of jointed rock masses.展开更多
High stress in surrounding rock will lead to serious problems,e.g.,rock burst in hard rock and large deformation in soft rock.The applied support system under high in-situ stress conditions should be able to carry hig...High stress in surrounding rock will lead to serious problems,e.g.,rock burst in hard rock and large deformation in soft rock.The applied support system under high in-situ stress conditions should be able to carry high load and also accommodate large deformation without experiencing severe damage.In this paper,a specially designed energy-absorbing component for rock bolt and cable that can solve the above problems was proposed.The energy-absorbing component can provide support resistance by plastic deformation of the metal including constraint annulus and compression pipe.For practical engineering,two forms were proposed.One was installed in the surrounding rock by reaming,and the other was installed directly outside the surrounding rock.During the dilation of the surrounding rock,the relative displacement of constraint annulus and compression pipe occurs,resulting in deformation resistance.Deformation resistance is transmitted to the rock bolt or cable,providing support resistance.The lab test and numerical simulation showed that the energy-absorbing component can perfectly achieve the large deformation effect,the deformation amount is as high as 694 mm,and the bearing capacity is stable at 367 kN.The field application tests were carried out in the mining roadway of Xinjulong coal mine,and the results showed that the new type of cable can ensure itself not to break under the condition of large deformation of the surrounding rock.The energy-absorbing component has the superiorities of performing large constant resistance and controllable deformation to effectively control the unpredictable disasters such as large deformation in soft rock and rock burst in hard rock encountered in deep strata.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
基金partially funded by the National Natural Science Foundation of China(Grant Nos.52179098 and 41907251)the State Scholarship Fund of China(Grant No.202306650001).
文摘In geotechnical engineering,rock bolts are commonly used for reinforcement,while the surrounding rock mass bears varying degrees of shear loads.The shear rate affects the stability of bolted rock joints,especially in projects susceptible to dynamic shear loads.In laboratory experiments,fully-grouted bolts and energy-absorbing bolts were used as research objects,and artificial rock specimens with rough joints were fabricated to analyze the shear characteristics and damage mechanisms of bolted rock joints under cyclic shear conditions and different shear velocities.The results showed that as the shear rate increased,the shear strength of bolted rock joint specimens decreased.Degradation of asperities resulted in no obvious peak shear stress in the specimens.Energy-absorbing bolts exhibited greater deformation capacity,with significant necking phenomena and the ability to withstand larger shear displacements.In contrast,fully-grouted bolts,which have threaded surfaces that provide higher bonding performance,exhibited a reduced capacity for plastic deformation and were prone to breaking under smaller shear displacements.Although the shear stiffness of specimens reinforced by energy-absorbing bolts was slightly lower than that of fully-grouted bolt specimens,they demonstrated greater stability under various shear rates.The absorbed shear energy showed that energy-absorbing bolts had superior coordinated deformation capabilities,thus exhibiting greater absorbed shear energy than fully-grouted bolts.Overall,fully-grouted bolts are more suitable for projects requiring higher rock shear strength and overall stiffness.In contrast,energy-absorbing bolts are more suitable for coping with dynamic or fluctuating load conditions to maintain the relative stability of jointed rock masses.
基金partially funded by National Natural Science Foundation of China(Nos.52179098 and 41907251).
文摘High stress in surrounding rock will lead to serious problems,e.g.,rock burst in hard rock and large deformation in soft rock.The applied support system under high in-situ stress conditions should be able to carry high load and also accommodate large deformation without experiencing severe damage.In this paper,a specially designed energy-absorbing component for rock bolt and cable that can solve the above problems was proposed.The energy-absorbing component can provide support resistance by plastic deformation of the metal including constraint annulus and compression pipe.For practical engineering,two forms were proposed.One was installed in the surrounding rock by reaming,and the other was installed directly outside the surrounding rock.During the dilation of the surrounding rock,the relative displacement of constraint annulus and compression pipe occurs,resulting in deformation resistance.Deformation resistance is transmitted to the rock bolt or cable,providing support resistance.The lab test and numerical simulation showed that the energy-absorbing component can perfectly achieve the large deformation effect,the deformation amount is as high as 694 mm,and the bearing capacity is stable at 367 kN.The field application tests were carried out in the mining roadway of Xinjulong coal mine,and the results showed that the new type of cable can ensure itself not to break under the condition of large deformation of the surrounding rock.The energy-absorbing component has the superiorities of performing large constant resistance and controllable deformation to effectively control the unpredictable disasters such as large deformation in soft rock and rock burst in hard rock encountered in deep strata.
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.
