An Equivalent Radial Stiffness Method of Laboratory SEPT on Anchorage Performance Prediction of Rockbolts under Different Field Geoconditions
The short encapsulation pull-out test (SEPT) is extensively used in rockbolting research or engineering. The field SEPT is time-consuming and labor-intensive, and its result is only applicable to the tested in situ. The laboratory SEPT is usually employed in theoretical rockbolting research due to i...
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2021-08-01
|
| Series: | Applied Sciences |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2076-3417/11/17/8041 |
| _version_ | 1797521658451329024 |
|---|---|
| author | Ming Zhang Jun Han Zuoqing Bi Chen Cao Tao Wu Shuangwen Ma |
| author_facet | Ming Zhang Jun Han Zuoqing Bi Chen Cao Tao Wu Shuangwen Ma |
| author_sort | Ming Zhang |
| collection | DOAJ |
| description | The short encapsulation pull-out test (SEPT) is extensively used in rockbolting research or engineering. The field SEPT is time-consuming and labor-intensive, and its result is only applicable to the tested in situ. The laboratory SEPT is usually employed in theoretical rockbolting research due to its easily controlled variables. However, the design of laboratory SEPT is quite different, as there is no standard testing method, resulting in the applicability and limitations of each study not being clear. Accordingly, the aim of this paper is to bridge the gap between laboratory SEPT research and field application. On the basis of thick-walled cylinder theory, a mechanical model of a rock bolt subjected to axial load was established under consideration of the deformational behavior of confining materials around the bolt. Plane stress analysis was introduced to derive the analytical relationship between the axial force of the bolt and the deformation of the confining materials. A new approach of laboratory SEPT sample design was established, namely, equivalent radial stiffness theory, to simulate anchorage performance in a specific in-situ geocondition. Consequently, the field SETP could be replaced by laboratory testing using properly designed bolting samples with a certain level of accuracy. In addition, the application scope of previous laboratory SEPT research could be accurately defined. Laboratory SEPT was carried out to study the anchoring performance of right spiral rebar bolts under different confining materials. Poly Vinyl Chloride (PVC) tubes with a thickness of 31 mm, #60 aluminum (Al) tubes with a thickness of 5.8 mm, and #20 steel tubes with a thickness of 5.5, 7.0 mm were used in sample preparation to simulate soft, medium, and hard surrounding rocks in the field. The anchorage performance of the bolt under different geoconditions was systematically proposed, which provides a technical approach for similar research using different anchoring materials. A negative exponential expression formulating the axial load capacity of the right spiral bolts for the full spectrum of the surrounding rocks’ strength was derived on the basis of theoretical analysis and data regression. It can be used for preliminary reinforcement design, as well as the accurate key parameter setting in the numerical calculation of roadway deformation using right spiral bolts. The theoretical prediction is highly consistent with the testing results in the literature, which confirms the validity and reliability of this research. This study contributes to the establishment of a laboratory SEPT standard in rock mechanics. |
| first_indexed | 2024-03-10T08:15:40Z |
| format | Article |
| id | doaj.art-761b2ac676724c078714bd8202fbe8e3 |
| institution | Directory Open Access Journal |
| issn | 2076-3417 |
| language | English |
| last_indexed | 2024-03-10T08:15:40Z |
| publishDate | 2021-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Applied Sciences |
| spelling | doaj.art-761b2ac676724c078714bd8202fbe8e32023-11-22T10:20:40ZengMDPI AGApplied Sciences2076-34172021-08-011117804110.3390/app11178041An Equivalent Radial Stiffness Method of Laboratory SEPT on Anchorage Performance Prediction of Rockbolts under Different Field GeoconditionsMing Zhang0Jun Han1Zuoqing Bi2Chen Cao3Tao Wu4Shuangwen Ma5College of Mining, Liaoning Technical University, Fuxin 123000, ChinaCollege of Mining, Liaoning Technical University, Fuxin 123000, ChinaCollege of Mining, Liaoning Technical University, Fuxin 123000, ChinaCollege of Mining, Liaoning Technical University, Fuxin 123000, ChinaShenfu Economic Development Zone Haiwan Coal Mine Co., Ltd., Yulin 719300, ChinaCollege of Mining, Liaoning Technical University, Fuxin 123000, ChinaThe short encapsulation pull-out test (SEPT) is extensively used in rockbolting research or engineering. The field SEPT is time-consuming and labor-intensive, and its result is only applicable to the tested in situ. The laboratory SEPT is usually employed in theoretical rockbolting research due to its easily controlled variables. However, the design of laboratory SEPT is quite different, as there is no standard testing method, resulting in the applicability and limitations of each study not being clear. Accordingly, the aim of this paper is to bridge the gap between laboratory SEPT research and field application. On the basis of thick-walled cylinder theory, a mechanical model of a rock bolt subjected to axial load was established under consideration of the deformational behavior of confining materials around the bolt. Plane stress analysis was introduced to derive the analytical relationship between the axial force of the bolt and the deformation of the confining materials. A new approach of laboratory SEPT sample design was established, namely, equivalent radial stiffness theory, to simulate anchorage performance in a specific in-situ geocondition. Consequently, the field SETP could be replaced by laboratory testing using properly designed bolting samples with a certain level of accuracy. In addition, the application scope of previous laboratory SEPT research could be accurately defined. Laboratory SEPT was carried out to study the anchoring performance of right spiral rebar bolts under different confining materials. Poly Vinyl Chloride (PVC) tubes with a thickness of 31 mm, #60 aluminum (Al) tubes with a thickness of 5.8 mm, and #20 steel tubes with a thickness of 5.5, 7.0 mm were used in sample preparation to simulate soft, medium, and hard surrounding rocks in the field. The anchorage performance of the bolt under different geoconditions was systematically proposed, which provides a technical approach for similar research using different anchoring materials. A negative exponential expression formulating the axial load capacity of the right spiral bolts for the full spectrum of the surrounding rocks’ strength was derived on the basis of theoretical analysis and data regression. It can be used for preliminary reinforcement design, as well as the accurate key parameter setting in the numerical calculation of roadway deformation using right spiral bolts. The theoretical prediction is highly consistent with the testing results in the literature, which confirms the validity and reliability of this research. This study contributes to the establishment of a laboratory SEPT standard in rock mechanics.https://www.mdpi.com/2076-3417/11/17/8041SEPTequivalent radial stiffnesspeak anchorage forceconfinementright spiral bolt |
| spellingShingle | Ming Zhang Jun Han Zuoqing Bi Chen Cao Tao Wu Shuangwen Ma An Equivalent Radial Stiffness Method of Laboratory SEPT on Anchorage Performance Prediction of Rockbolts under Different Field Geoconditions Applied Sciences SEPT equivalent radial stiffness peak anchorage force confinement right spiral bolt |
| title | An Equivalent Radial Stiffness Method of Laboratory SEPT on Anchorage Performance Prediction of Rockbolts under Different Field Geoconditions |
| title_full | An Equivalent Radial Stiffness Method of Laboratory SEPT on Anchorage Performance Prediction of Rockbolts under Different Field Geoconditions |
| title_fullStr | An Equivalent Radial Stiffness Method of Laboratory SEPT on Anchorage Performance Prediction of Rockbolts under Different Field Geoconditions |
| title_full_unstemmed | An Equivalent Radial Stiffness Method of Laboratory SEPT on Anchorage Performance Prediction of Rockbolts under Different Field Geoconditions |
| title_short | An Equivalent Radial Stiffness Method of Laboratory SEPT on Anchorage Performance Prediction of Rockbolts under Different Field Geoconditions |
| title_sort | equivalent radial stiffness method of laboratory sept on anchorage performance prediction of rockbolts under different field geoconditions |
| topic | SEPT equivalent radial stiffness peak anchorage force confinement right spiral bolt |
| url | https://www.mdpi.com/2076-3417/11/17/8041 |
| work_keys_str_mv | AT mingzhang anequivalentradialstiffnessmethodoflaboratoryseptonanchorageperformancepredictionofrockboltsunderdifferentfieldgeoconditions AT junhan anequivalentradialstiffnessmethodoflaboratoryseptonanchorageperformancepredictionofrockboltsunderdifferentfieldgeoconditions AT zuoqingbi anequivalentradialstiffnessmethodoflaboratoryseptonanchorageperformancepredictionofrockboltsunderdifferentfieldgeoconditions AT chencao anequivalentradialstiffnessmethodoflaboratoryseptonanchorageperformancepredictionofrockboltsunderdifferentfieldgeoconditions AT taowu anequivalentradialstiffnessmethodoflaboratoryseptonanchorageperformancepredictionofrockboltsunderdifferentfieldgeoconditions AT shuangwenma anequivalentradialstiffnessmethodoflaboratoryseptonanchorageperformancepredictionofrockboltsunderdifferentfieldgeoconditions AT mingzhang equivalentradialstiffnessmethodoflaboratoryseptonanchorageperformancepredictionofrockboltsunderdifferentfieldgeoconditions AT junhan equivalentradialstiffnessmethodoflaboratoryseptonanchorageperformancepredictionofrockboltsunderdifferentfieldgeoconditions AT zuoqingbi equivalentradialstiffnessmethodoflaboratoryseptonanchorageperformancepredictionofrockboltsunderdifferentfieldgeoconditions AT chencao equivalentradialstiffnessmethodoflaboratoryseptonanchorageperformancepredictionofrockboltsunderdifferentfieldgeoconditions AT taowu equivalentradialstiffnessmethodoflaboratoryseptonanchorageperformancepredictionofrockboltsunderdifferentfieldgeoconditions AT shuangwenma equivalentradialstiffnessmethodoflaboratoryseptonanchorageperformancepredictionofrockboltsunderdifferentfieldgeoconditions |