This paper investigated the stress evolution,displacement field,local deformation and its overall distribution,and failure characteristics of the anchorage structure of surrounding rock with different rockbolt spacing...This paper investigated the stress evolution,displacement field,local deformation and its overall distribution,and failure characteristics of the anchorage structure of surrounding rock with different rockbolt spacing through the model experiments.The influences of the pre-tightening force and spacing of rockbolt on the support strength of the anchorage structure of surrounding rock were analyzed by the simulation using FLAC3D numerical software.The support scheme of the excavated roadway was then designed,and the effectiveness of this support scheme was further verified by the displacement measurement of the roadway.The results showed that the maximum displacement between the roof and floor of the west wing track roadway in Kouzidong coal mine,China is about 42 mm,and the maximum displacement between its both sides is about 72 mm,indicating that the support scheme proposed in this study can ensure the stability and safety of the excavated roadway.展开更多
In order to study the failure process of an anchorage structure and the evolution law of the body＇s defor- mation field, anchor push-out tests were carried out based on digital speckle correlation methods （DSCM）. T...In order to study the failure process of an anchorage structure and the evolution law of the body＇s defor- mation field, anchor push-out tests were carried out based on digital speckle correlation methods （DSCM）. The stress distribution of the anchorage interface was investigated using the particle flow numerical simulation method. The results indicate that there are three stages in the deformation and fail- ure process of an anchorage structure： elastic bonding stage, a de-bonding stage and a failure stage. The stress distribution in the interface controls the stability of the structure. In the elastic bonding stage, the shear stress peak point of the interface is close to the loading end, and the displacement field gradually develops into a ＂V＂ shape, in the de-bonding stage, there is a shear stress plateau in the center of the anchorage section, and shear strain localization begins to form in the deformation field. In the failure stage, the bonding of the interface fails rapidly and the shear stress peak point moves to the anchorage free end. The anchorage structure moves integrally along the macro-cracl~ The de-bonding stage is a research focus in the deformation and failure process of an anchorage structure, and plays an important guiding role in roadway support design and prediction of the stability of the surrounding rock.展开更多
To thoroughly investigate the damage evolution of anchorage structures under corrosive conditions,laboratory simulations of corrosive environments were conducted,including corrosion tests and mechanical performance ev...To thoroughly investigate the damage evolution of anchorage structures under corrosive conditions,laboratory simulations of corrosive environments were conducted,including corrosion tests and mechanical performance evaluations on anchorage systems.Based on experimental results,relationships were analyzed between factors(prestress,pH value,and anti-corrosion methods)and the corrosion degree,macro-micro characteristics,and mechanical performance degradation patterns of specimens.The results of the test indicated that:(1)the corrosion of coal bodies increases over time,and lower pH environments correspond to lower uniaxial compressive strength of coal bodies;(2)the corrosion of the rock bolts increases over time,the maximum mechanical performance in the rock bolts loss occurs at pH=5.0,and higher prestress of the rock bolts leads to greater mechanical degradation,and galvanization effectively reduces corrosion in functional rock bolts;(3)the degree of corrosion in the anchorage bodies has increases over time,pH=5.0 causes maximum bond strength of the anchorage bodies property loss and increases the prestress in the anchorage bodies exacerbates bond strength degradation,and double anti-protected anchorage bodies show less bond strength loss than ordinary ones.The corrosion-induced structural deterioration of underground anchorage systems leads to significant mechanical performance degradation,potentially causing support failure,surrounding rock instability,and roof fall disasters.Greater attention therefore needs to be paid to this area.展开更多
In order to investigate the failure mechanism of the reinforced muddy soft rock under the influence of the hydration reaction when ground water is present,a series of confined compressive tests and Acoustic Emission(A...In order to investigate the failure mechanism of the reinforced muddy soft rock under the influence of the hydration reaction when ground water is present,a series of confined compressive tests and Acoustic Emission(AE)recordings were conducted subject to various moisture content levels and lateral confining stresses.It was found that the failure modes of the reinforced rock specimen were affected by the moisture content level and the lateral stress σ_(2) in a way that the load bearing capacity of the reinforced rock would increase with the lateral stress σ_(2) but decrease as the moisture content increased.An increase in the moisture content would reduce the extent of the influence of the lateral stress on the load bearing capacity of the reinforced rock.In addition,much less AE counts were recorded when the moisture content increased indicating that the crack initiation and propagation in this case was easier due to the reduction of the required external input energy.With increasing moisture content,the failure mode of the specimen gradually changes from sudden and brittle to progressive and ductile.Moreover,the hydration reaction became more significant leading to a complete debonding between the grout and the rock.Consequently,the reinforcement provided by the rock bolt to the rock became negligible.展开更多
Concrete structure is commonly used in the anchorages of a large cable-suspended pipeline crossing construction.With the increase of span and load,the stress on the concrete anchorages may rise rapidly.In case of trad...Concrete structure is commonly used in the anchorages of a large cable-suspended pipeline crossing construction.With the increase of span and load,the stress on the concrete anchorages may rise rapidly.In case of traditional anchoring structurefixed by anchor rods,concrete cracking will occur,thereby reducing the anchorage life.To solve this problem,the pre-stressed structure was designed to effectively improve the ef-ficiency of anchoring and reduce engineering cost.In the crossing construction of ChinaeMyanmar Gas Pipeline,the pre-stressed technology was used to establish an effective pre-stressed anchoring system,which integrates the pre-stressed structures(e.g.tunnel anchorages in the anchors)and the optimization measures(e.g.positioning mode,anchorage structure,concrete placement,pre-stressed,and medium injection),in line with the crossing structure and load features of this project.The system can delay the occurrence of concrete cracking and enhance the stress durability of the structure and anchoring efficiency.This technology has been successfully applied in the crossing construction of Chi-naeMyanmar Gas Pipeline,with good economic and social benefits,indicating that this technology is a new effective solution to the opti-mization of suspended pipeline anchorage structures,providing technical support for the development of pipeline crossing structure.展开更多
基金supported by the National Natural Science Foundation of China(51734009)National Key Basic Research and Development Program of China(2017YFC0603001).
文摘This paper investigated the stress evolution,displacement field,local deformation and its overall distribution,and failure characteristics of the anchorage structure of surrounding rock with different rockbolt spacing through the model experiments.The influences of the pre-tightening force and spacing of rockbolt on the support strength of the anchorage structure of surrounding rock were analyzed by the simulation using FLAC3D numerical software.The support scheme of the excavated roadway was then designed,and the effectiveness of this support scheme was further verified by the displacement measurement of the roadway.The results showed that the maximum displacement between the roof and floor of the west wing track roadway in Kouzidong coal mine,China is about 42 mm,and the maximum displacement between its both sides is about 72 mm,indicating that the support scheme proposed in this study can ensure the stability and safety of the excavated roadway.
基金financially supported by the National Key Basic Research Program of China (No.2010CB226805)the National Natural Science Foundation of China (Nos.51474136 and 51474013)+1 种基金the Opening Project Fund of State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology (No.MDPC2013KF06)the Research Award Fund for the Excellent Youth of Shandong University of Science and Technology (No.2011KYJQ106)
文摘In order to study the failure process of an anchorage structure and the evolution law of the body＇s defor- mation field, anchor push-out tests were carried out based on digital speckle correlation methods （DSCM）. The stress distribution of the anchorage interface was investigated using the particle flow numerical simulation method. The results indicate that there are three stages in the deformation and fail- ure process of an anchorage structure： elastic bonding stage, a de-bonding stage and a failure stage. The stress distribution in the interface controls the stability of the structure. In the elastic bonding stage, the shear stress peak point of the interface is close to the loading end, and the displacement field gradually develops into a ＂V＂ shape, in the de-bonding stage, there is a shear stress plateau in the center of the anchorage section, and shear strain localization begins to form in the deformation field. In the failure stage, the bonding of the interface fails rapidly and the shear stress peak point moves to the anchorage free end. The anchorage structure moves integrally along the macro-cracl~ The de-bonding stage is a research focus in the deformation and failure process of an anchorage structure, and plays an important guiding role in roadway support design and prediction of the stability of the surrounding rock.
基金supported by the National Natural Science Foundation of China:Damage Mechanism and Stability Precursor Characteristics of Gradient Enclosure Structures in Impact Hazardous Roadways under Dynamic and Static Loads(No.52374201).
文摘To thoroughly investigate the damage evolution of anchorage structures under corrosive conditions,laboratory simulations of corrosive environments were conducted,including corrosion tests and mechanical performance evaluations on anchorage systems.Based on experimental results,relationships were analyzed between factors(prestress,pH value,and anti-corrosion methods)and the corrosion degree,macro-micro characteristics,and mechanical performance degradation patterns of specimens.The results of the test indicated that:(1)the corrosion of coal bodies increases over time,and lower pH environments correspond to lower uniaxial compressive strength of coal bodies;(2)the corrosion of the rock bolts increases over time,the maximum mechanical performance in the rock bolts loss occurs at pH=5.0,and higher prestress of the rock bolts leads to greater mechanical degradation,and galvanization effectively reduces corrosion in functional rock bolts;(3)the degree of corrosion in the anchorage bodies has increases over time,pH=5.0 causes maximum bond strength of the anchorage bodies property loss and increases the prestress in the anchorage bodies exacerbates bond strength degradation,and double anti-protected anchorage bodies show less bond strength loss than ordinary ones.The corrosion-induced structural deterioration of underground anchorage systems leads to significant mechanical performance degradation,potentially causing support failure,surrounding rock instability,and roof fall disasters.Greater attention therefore needs to be paid to this area.
基金financially supported by the National Natural Science Foundation of China(U22A20165,12072102,52174089).
文摘In order to investigate the failure mechanism of the reinforced muddy soft rock under the influence of the hydration reaction when ground water is present,a series of confined compressive tests and Acoustic Emission(AE)recordings were conducted subject to various moisture content levels and lateral confining stresses.It was found that the failure modes of the reinforced rock specimen were affected by the moisture content level and the lateral stress σ_(2) in a way that the load bearing capacity of the reinforced rock would increase with the lateral stress σ_(2) but decrease as the moisture content increased.An increase in the moisture content would reduce the extent of the influence of the lateral stress on the load bearing capacity of the reinforced rock.In addition,much less AE counts were recorded when the moisture content increased indicating that the crack initiation and propagation in this case was easier due to the reduction of the required external input energy.With increasing moisture content,the failure mode of the specimen gradually changes from sudden and brittle to progressive and ductile.Moreover,the hydration reaction became more significant leading to a complete debonding between the grout and the rock.Consequently,the reinforcement provided by the rock bolt to the rock became negligible.
基金2011-2012 S&T project of CNPC Chuanqing Drilling Engineering Co.,“Study on Applicability of crossing construction technology in Chinae-Myanmar pipeline project”。
文摘Concrete structure is commonly used in the anchorages of a large cable-suspended pipeline crossing construction.With the increase of span and load,the stress on the concrete anchorages may rise rapidly.In case of traditional anchoring structurefixed by anchor rods,concrete cracking will occur,thereby reducing the anchorage life.To solve this problem,the pre-stressed structure was designed to effectively improve the ef-ficiency of anchoring and reduce engineering cost.In the crossing construction of ChinaeMyanmar Gas Pipeline,the pre-stressed technology was used to establish an effective pre-stressed anchoring system,which integrates the pre-stressed structures(e.g.tunnel anchorages in the anchors)and the optimization measures(e.g.positioning mode,anchorage structure,concrete placement,pre-stressed,and medium injection),in line with the crossing structure and load features of this project.The system can delay the occurrence of concrete cracking and enhance the stress durability of the structure and anchoring efficiency.This technology has been successfully applied in the crossing construction of Chi-naeMyanmar Gas Pipeline,with good economic and social benefits,indicating that this technology is a new effective solution to the opti-mization of suspended pipeline anchorage structures,providing technical support for the development of pipeline crossing structure.
