{"id":{"repo_id":"ghent","oai_identifier":"oai:archive.ugent.be:8563084"},"canonical_url":"https://search.dev.ndltd.org/etd/ghent/oai:archive.ugent.be:8563084","repository":{"repo_id":"ghent","name":"Ghent University","base_url":"https://biblio.ugent.be/oai"},"display":{"title":"Experimental assessment of the mechanical behavior of immersion joints and a seismic mitigation method in immersed tunnels","abstract":"With the rapid progress of urbanization, an increasing number of infrastructure works have been constructed by engineers around the world since the past two centuries, among which many tunnels. Due to the advantages compared to other tunnel types, immersed tunnel techniques are widely adopted and nowadays there are more than 200 immersed tunnels worldwide. The immersion joints, which are between the adjacent tunnel elements, are normally regarded as the weakest parts in the tunnel due to their smaller stiffness than that of the elements. Moreover, the immersion joint is the key component in the water proof system. When an immersed tunnel experiences various loadings, i.e. earthquakes, differential settlement, sinking ships or anchorage impact, deformations occur in the joint and excessive deformations could cause possible damage to the joint, resulting in water leakage which jeopardizes the safety of the immersed tunnel. As known, the configuration of an immersion joint is complicated, mainly involving the primary rubber seal, the secondary rubber seal, the shear keys, the steel shell and the pre-stressing cables. Such a complex configuration leads to difficulties to investigate the behavior of the joint. To have a comprehensive understanding of that, an experimental investigation on the joint subjected to combined loadings is reported in the present thesis. In particular, the behavior of the joint subjected to excessive shear deformation is investigated and subsequently, the failure behavior is also included. It is widely recognized that the shear keys have an important contribution to the shear behavior of the joint. However, the failure behavior of the joint with both the shear keys and the rubber seal is largely unknown due to the lack of experimental investigations. Moreover, it is proved that the flexible immersion joint has a contribution in the seismic response reduction but the application of seismic mitigation devices in the joint has never been considered though such concept has been accepted for buildings for decades. Therefore, the main part of the thesis was divided into two parts, more specifically the mechanical behavior of the joint and the seismic mitigation for immersion joint respectively. Based on an extensive literature review, an experimental program has been elaborated in order to investigate the mechanical behavior of the joint subjected to axial, bending and shear loadings. A geometric scale of 1:10 was selected for technical reasons, such as manufacturing, testing and measurements. Based on that, two tunnel elements, between which an immersion joint was positioned, were designed as well as the rubber seal and the shear keys. The dimensions of a single element are 3800mm x 1150mm x 1250mm with the walls and slabs having a thickness of 150mm. The cross-sectional dimensions of the rubber seal are 37.5mm x 70mm (flange including) with a total length of 9.67m. Two types of shear keys have been investigated, namely steel shear keys and concrete shear keys and each type of the shear keys was divided into two groups depending on their position in the joint and the loading situation. The steel shear keys were connected to the element by bolts while the concrete shear keys were casted together with the element to increase the shear strength. For the model specimens, a unique test set-up has been developed allowing that one element is movable while the other one is fixed, resulting in an axial, bending and shear deformations in the joint respectively. Only horizontal loading was applied in this experiment. The axial load and the bending moment were provided by a set of four hydraulic jacks which are controlled independently while the shear force was applied by an additional jack. Further, a testing procedure was elaborated, consisting of three loading protocols, namely axial compression, compression-bending moment and compression-shear loading cases. For the axial loading case, the hydraulic jacks first provided the gradually increasing axial force then the jacks were unloaded. For the compression-bending case the axial force was applied to an specific value to simulate the initial water pressure in the joint and then a bending moment was imposed. The immersion joint was allowed to rotate, resulting in the occurrence of an opening of the joint. For the shear loading cases, an axial force was also applied at the beginning followed by a reciprocating shear force with increasing amplitude. The shear force was increased until all the shear keys failed. During the experiments, measurements were executed after each successive increase of the load or displacement, comprising axial and shear deformations. Regarding the axial and flexural performance of the joint, the compression-release curve and the bending moment-rotation curves with different levels of axial forces were obtained. Through the obtained load-deformation curves, both the axial stiffness and the flexural stiffness of the joint were derived for use in practice. During this testing cases, a hysteretic loop was observed in both axial and flexural behavior of the joint, indicating that the rubber seal is not perfectly hyper-elastic material as assumed and energy-dissipation did occur. Moreover, an asymmetric bending behavior was observed as the axial force increased. The static and dynamic behavior of the joint were investigated by imposing static and dynamic shear loading respectively. The static and dynamic load-displacement curves of the joint with different loading scenarios were obtained. Accordingly, the static and dynamic shear stiffness of the joint were derived as well. A comparison was made between the static and dynamic shear performance of the joint. The failure behavior of the joint with the steel shear keys and concrete shear keys were investigated by applying reciprocating shear loads with increasing amplitude under a constant axial force. The failure mode of the joint with these two types of shear keys as well as the shear capacity of the joint were obtained. Both series of test results show that the shear keys were not activated at the same time, resulting in a difference between the design shear capacity and experimental one. Finally, a significant contribution of the rubber seal in the shear direction was found, indicating that the shear behavior of the rubber seal should be taken into account in the design procedure. A general literature study with respect to seismic mitigation methods was performed serving as a starting point for the application to immersion joints. To achieve this, a buckling energydissipation device (BEDD) on the basis of the Buckling Restrained Brace (BRB) was introduced and a detailed design procedure for the seismic mitigation device in the joint was provided supposing that the device can work in coordination with the joint in such a way that the maximum energy dissipation is reached. In order to validate the design procedure, a largescale experiment was conducted on an immersion joint subjected to compression-bending moment cases. The bending moment-rotation curves of the joint with seismic mitigation devices as well as the hysteretic performance of the device itself were obtained through axial transducers and strain gauges on the device. It was experimentally proved that the hysteretic performance of the joint was enhanced by using the seismic mitigation device though the performance of the device itself did not meet the expectation. However, it indicated that such application of the seismic mitigation method has a high potential in energy dissipation in immersion joints. In the presented PhD thesis, the mechanical behavior of the joint subjected to axial, flexural and shear loadings and the seismic mitigation method for immersion joints have been studied comprehensively in an experimental way. As the first attempt ever on such issue, the results gained from these investigation give clear insights on the behavior of joint under different loading scenarios. The obtained stiffnesses can be used in further numerical analyses. The proposed seismic mitigation method for immersion joints is shown to be feasible not only to enhance the seismic performance of the joint but also to provide an additional way for energy dissipation of immersed tunnels. The material characteristics of the rubber seal are found to play a much more important role than what is expected from conventional design.","abstract_html":"With the rapid progress of urbanization, an increasing number of infrastructure works have been constructed by engineers around the world since the past two centuries, among which many tunnels. Due to the advantages compared to other tunnel types, immersed tunnel techniques are widely adopted and nowadays there are more than 200 immersed tunnels worldwide. The immersion joints, which are between the adjacent tunnel elements, are normally regarded as the weakest parts in the tunnel due to their smaller stiffness than that of the elements. Moreover, the immersion joint is the key component in the water proof system. When an immersed tunnel experiences various loadings, i.e. earthquakes, differential settlement, sinking ships or anchorage impact, deformations occur in the joint and excessive deformations could cause possible damage to the joint, resulting in water leakage which jeopardizes the safety of the immersed tunnel. As known, the configuration of an immersion joint is complicated, mainly involving the primary rubber seal, the secondary rubber seal, the shear keys, the steel shell and the pre-stressing cables. Such a complex configuration leads to difficulties to investigate the behavior of the joint. To have a comprehensive understanding of that, an experimental investigation on the joint subjected to combined loadings is reported in the present thesis. In particular, the behavior of the joint subjected to excessive shear deformation is investigated and subsequently, the failure behavior is also included. It is widely recognized that the shear keys have an important contribution to the shear behavior of the joint. However, the failure behavior of the joint with both the shear keys and the rubber seal is largely unknown due to the lack of experimental investigations. Moreover, it is proved that the flexible immersion joint has a contribution in the seismic response reduction but the application of seismic mitigation devices in the joint has never been considered though such concept has been accepted for buildings for decades. Therefore, the main part of the thesis was divided into two parts, more specifically the mechanical behavior of the joint and the seismic mitigation for immersion joint respectively. Based on an extensive literature review, an experimental program has been elaborated in order to investigate the mechanical behavior of the joint subjected to axial, bending and shear loadings. A geometric scale of 1:10 was selected for technical reasons, such as manufacturing, testing and measurements. Based on that, two tunnel elements, between which an immersion joint was positioned, were designed as well as the rubber seal and the shear keys. The dimensions of a single element are 3800mm x 1150mm x 1250mm with the walls and slabs having a thickness of 150mm. The cross-sectional dimensions of the rubber seal are 37.5mm x 70mm (flange including) with a total length of 9.67m. Two types of shear keys have been investigated, namely steel shear keys and concrete shear keys and each type of the shear keys was divided into two groups depending on their position in the joint and the loading situation. The steel shear keys were connected to the element by bolts while the concrete shear keys were casted together with the element to increase the shear strength. For the model specimens, a unique test set-up has been developed allowing that one element is movable while the other one is fixed, resulting in an axial, bending and shear deformations in the joint respectively. Only horizontal loading was applied in this experiment. The axial load and the bending moment were provided by a set of four hydraulic jacks which are controlled independently while the shear force was applied by an additional jack. Further, a testing procedure was elaborated, consisting of three loading protocols, namely axial compression, compression-bending moment and compression-shear loading cases. For the axial loading case, the hydraulic jacks first provided the gradually increasing axial force then the jacks were unloaded. For the compression-bending case the axial force was applied to an specific value to simulate the initial water pressure in the joint and then a bending moment was imposed. The immersion joint was allowed to rotate, resulting in the occurrence of an opening of the joint. For the shear loading cases, an axial force was also applied at the beginning followed by a reciprocating shear force with increasing amplitude. The shear force was increased until all the shear keys failed. During the experiments, measurements were executed after each successive increase of the load or displacement, comprising axial and shear deformations. Regarding the axial and flexural performance of the joint, the compression-release curve and the bending moment-rotation curves with different levels of axial forces were obtained. Through the obtained load-deformation curves, both the axial stiffness and the flexural stiffness of the joint were derived for use in practice. During this testing cases, a hysteretic loop was observed in both axial and flexural behavior of the joint, indicating that the rubber seal is not perfectly hyper-elastic material as assumed and energy-dissipation did occur. Moreover, an asymmetric bending behavior was observed as the axial force increased. The static and dynamic behavior of the joint were investigated by imposing static and dynamic shear loading respectively. The static and dynamic load-displacement curves of the joint with different loading scenarios were obtained. Accordingly, the static and dynamic shear stiffness of the joint were derived as well. A comparison was made between the static and dynamic shear performance of the joint. The failure behavior of the joint with the steel shear keys and concrete shear keys were investigated by applying reciprocating shear loads with increasing amplitude under a constant axial force. The failure mode of the joint with these two types of shear keys as well as the shear capacity of the joint were obtained. Both series of test results show that the shear keys were not activated at the same time, resulting in a difference between the design shear capacity and experimental one. Finally, a significant contribution of the rubber seal in the shear direction was found, indicating that the shear behavior of the rubber seal should be taken into account in the design procedure. A general literature study with respect to seismic mitigation methods was performed serving as a starting point for the application to immersion joints. To achieve this, a buckling energydissipation device (BEDD) on the basis of the Buckling Restrained Brace (BRB) was introduced and a detailed design procedure for the seismic mitigation device in the joint was provided supposing that the device can work in coordination with the joint in such a way that the maximum energy dissipation is reached. In order to validate the design procedure, a largescale experiment was conducted on an immersion joint subjected to compression-bending moment cases. The bending moment-rotation curves of the joint with seismic mitigation devices as well as the hysteretic performance of the device itself were obtained through axial transducers and strain gauges on the device. It was experimentally proved that the hysteretic performance of the joint was enhanced by using the seismic mitigation device though the performance of the device itself did not meet the expectation. However, it indicated that such application of the seismic mitigation method has a high potential in energy dissipation in immersion joints. In the presented PhD thesis, the mechanical behavior of the joint subjected to axial, flexural and shear loadings and the seismic mitigation method for immersion joints have been studied comprehensively in an experimental way. As the first attempt ever on such issue, the results gained from these investigation give clear insights on the behavior of joint under different loading scenarios. The obtained stiffnesses can be used in further numerical analyses. The proposed seismic mitigation method for immersion joints is shown to be feasible not only to enhance the seismic performance of the joint but also to provide an additional way for energy dissipation of immersed tunnels. The material characteristics of the rubber seal are found to play a much more important role than what is expected from conventional design.","abstract_has_math":false,"creators":["Xiao, Wenhao"],"institution":"Ghent University. Faculty of Engineering and Architecture","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["Taerwe, Luc","Yuan, Yong"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2018,"date_issued":"2018","date_published":"2018","updated_at":"2026-07-24T02:23:03Z","subjects":["Technology and Engineering"],"languages":["eng"],"rights":["info:eu-repo/semantics/openAccess"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["https://biblio.ugent.be/publication/8563084","urn:isbn:9789463550949","https://biblio.ugent.be/publication/8563084/file/8563093"],"render_values":[{"text":"https://biblio.ugent.be/publication/8563084","href":"https://biblio.ugent.be/publication/8563084","code":true},{"text":"urn:isbn:9789463550949","href":null,"code":true},{"text":"https://biblio.ugent.be/publication/8563084/file/8563093","href":"https://biblio.ugent.be/publication/8563084/file/8563093","code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/1854/LU-8563084","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Taerwe, Luc","Yuan, Yong"]},{"key":"dc:creator","label":"Author","values":["Xiao, Wenhao"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2018"]},{"key":"dc:publisher","label":"Institution","values":["Ghent University. 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Due to the advantages compared to other tunnel types, immersed tunnel techniques are widely adopted and nowadays there are more than 200 immersed tunnels worldwide. The immersion joints, which are between the adjacent tunnel elements, are normally regarded as the weakest parts in the tunnel due to their smaller stiffness than that of the elements. Moreover, the immersion joint is the key component in the water proof system. When an immersed tunnel experiences various loadings, i.e. earthquakes, differential settlement, sinking ships or anchorage impact, deformations occur in the joint and excessive deformations could cause possible damage to the joint, resulting in water leakage which jeopardizes the safety of the immersed tunnel. As known, the configuration of an immersion joint is complicated, mainly involving the primary rubber seal, the secondary rubber seal, the shear keys, the steel shell and the pre-stressing cables. Such a complex configuration leads to difficulties to investigate the behavior of the joint. To have a comprehensive understanding of that, an experimental investigation on the joint subjected to combined loadings is reported in the present thesis. In particular, the behavior of the joint subjected to excessive shear deformation is investigated and subsequently, the failure behavior is also included. It is widely recognized that the shear keys have an important contribution to the shear behavior of the joint. However, the failure behavior of the joint with both the shear keys and the rubber seal is largely unknown due to the lack of experimental investigations. Moreover, it is proved that the flexible immersion joint has a contribution in the seismic response reduction but the application of seismic mitigation devices in the joint has never been considered though such concept has been accepted for buildings for decades. Therefore, the main part of the thesis was divided into two parts, more specifically the mechanical behavior of the joint and the seismic mitigation for immersion joint respectively. Based on an extensive literature review, an experimental program has been elaborated in order to investigate the mechanical behavior of the joint subjected to axial, bending and shear loadings. A geometric scale of 1:10 was selected for technical reasons, such as manufacturing, testing and measurements. Based on that, two tunnel elements, between which an immersion joint was positioned, were designed as well as the rubber seal and the shear keys. The dimensions of a single element are 3800mm x 1150mm x 1250mm with the walls and slabs having a thickness of 150mm. The cross-sectional dimensions of the rubber seal are 37.5mm x 70mm (flange including) with a total length of 9.67m. Two types of shear keys have been investigated, namely steel shear keys and concrete shear keys and each type of the shear keys was divided into two groups depending on their position in the joint and the loading situation. The steel shear keys were connected to the element by bolts while the concrete shear keys were casted together with the element to increase the shear strength. For the model specimens, a unique test set-up has been developed allowing that one element is movable while the other one is fixed, resulting in an axial, bending and shear deformations in the joint respectively. Only horizontal loading was applied in this experiment. The axial load and the bending moment were provided by a set of four hydraulic jacks which are controlled independently while the shear force was applied by an additional jack. Further, a testing procedure was elaborated, consisting of three loading protocols, namely axial compression, compression-bending moment and compression-shear loading cases. For the axial loading case, the hydraulic jacks first provided the gradually increasing axial force then the jacks were unloaded. For the compression-bending case the axial force was applied to an specific value to simulate the initial water pressure in the joint and then a bending moment was imposed. The immersion joint was allowed to rotate, resulting in the occurrence of an opening of the joint. For the shear loading cases, an axial force was also applied at the beginning followed by a reciprocating shear force with increasing amplitude. The shear force was increased until all the shear keys failed. During the experiments, measurements were executed after each successive increase of the load or displacement, comprising axial and shear deformations. Regarding the axial and flexural performance of the joint, the compression-release curve and the bending moment-rotation curves with different levels of axial forces were obtained. Through the obtained load-deformation curves, both the axial stiffness and the flexural stiffness of the joint were derived for use in practice. During this testing cases, a hysteretic loop was observed in both axial and flexural behavior of the joint, indicating that the rubber seal is not perfectly hyper-elastic material as assumed and energy-dissipation did occur. Moreover, an asymmetric bending behavior was observed as the axial force increased. The static and dynamic behavior of the joint were investigated by imposing static and dynamic shear loading respectively. The static and dynamic load-displacement curves of the joint with different loading scenarios were obtained. Accordingly, the static and dynamic shear stiffness of the joint were derived as well. A comparison was made between the static and dynamic shear performance of the joint. The failure behavior of the joint with the steel shear keys and concrete shear keys were investigated by applying reciprocating shear loads with increasing amplitude under a constant axial force. The failure mode of the joint with these two types of shear keys as well as the shear capacity of the joint were obtained. Both series of test results show that the shear keys were not activated at the same time, resulting in a difference between the design shear capacity and experimental one. Finally, a significant contribution of the rubber seal in the shear direction was found, indicating that the shear behavior of the rubber seal should be taken into account in the design procedure. A general literature study with respect to seismic mitigation methods was performed serving as a starting point for the application to immersion joints. To achieve this, a buckling energydissipation device (BEDD) on the basis of the Buckling Restrained Brace (BRB) was introduced and a detailed design procedure for the seismic mitigation device in the joint was provided supposing that the device can work in coordination with the joint in such a way that the maximum energy dissipation is reached. In order to validate the design procedure, a largescale experiment was conducted on an immersion joint subjected to compression-bending moment cases. The bending moment-rotation curves of the joint with seismic mitigation devices as well as the hysteretic performance of the device itself were obtained through axial transducers and strain gauges on the device. It was experimentally proved that the hysteretic performance of the joint was enhanced by using the seismic mitigation device though the performance of the device itself did not meet the expectation. However, it indicated that such application of the seismic mitigation method has a high potential in energy dissipation in immersion joints. In the presented PhD thesis, the mechanical behavior of the joint subjected to axial, flexural and shear loadings and the seismic mitigation method for immersion joints have been studied comprehensively in an experimental way. As the first attempt ever on such issue, the results gained from these investigation give clear insights on the behavior of joint under different loading scenarios. The obtained stiffnesses can be used in further numerical analyses. The proposed seismic mitigation method for immersion joints is shown to be feasible not only to enhance the seismic performance of the joint but also to provide an additional way for energy dissipation of immersed tunnels. The material characteristics of the rubber seal are found to play a much more important role than what is expected from conventional design."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Experimental assessment of the mechanical behavior of immersion joints and a seismic mitigation method in immersed tunnels"]}]}],"canonical_facts":{"dc:contributor":["Taerwe, Luc","Yuan, Yong"],"dc:creator":["Xiao, Wenhao"],"dc:date":["2018"],"dc:description":["With the rapid progress of urbanization, an increasing number of infrastructure works have been constructed by engineers around the world since the past two centuries, among which many tunnels. Due to the advantages compared to other tunnel types, immersed tunnel techniques are widely adopted and nowadays there are more than 200 immersed tunnels worldwide. The immersion joints, which are between the adjacent tunnel elements, are normally regarded as the weakest parts in the tunnel due to their smaller stiffness than that of the elements. Moreover, the immersion joint is the key component in the water proof system. When an immersed tunnel experiences various loadings, i.e. earthquakes, differential settlement, sinking ships or anchorage impact, deformations occur in the joint and excessive deformations could cause possible damage to the joint, resulting in water leakage which jeopardizes the safety of the immersed tunnel. As known, the configuration of an immersion joint is complicated, mainly involving the primary rubber seal, the secondary rubber seal, the shear keys, the steel shell and the pre-stressing cables. Such a complex configuration leads to difficulties to investigate the behavior of the joint. To have a comprehensive understanding of that, an experimental investigation on the joint subjected to combined loadings is reported in the present thesis. In particular, the behavior of the joint subjected to excessive shear deformation is investigated and subsequently, the failure behavior is also included. It is widely recognized that the shear keys have an important contribution to the shear behavior of the joint. However, the failure behavior of the joint with both the shear keys and the rubber seal is largely unknown due to the lack of experimental investigations. Moreover, it is proved that the flexible immersion joint has a contribution in the seismic response reduction but the application of seismic mitigation devices in the joint has never been considered though such concept has been accepted for buildings for decades. Therefore, the main part of the thesis was divided into two parts, more specifically the mechanical behavior of the joint and the seismic mitigation for immersion joint respectively. Based on an extensive literature review, an experimental program has been elaborated in order to investigate the mechanical behavior of the joint subjected to axial, bending and shear loadings. A geometric scale of 1:10 was selected for technical reasons, such as manufacturing, testing and measurements. Based on that, two tunnel elements, between which an immersion joint was positioned, were designed as well as the rubber seal and the shear keys. The dimensions of a single element are 3800mm x 1150mm x 1250mm with the walls and slabs having a thickness of 150mm. The cross-sectional dimensions of the rubber seal are 37.5mm x 70mm (flange including) with a total length of 9.67m. Two types of shear keys have been investigated, namely steel shear keys and concrete shear keys and each type of the shear keys was divided into two groups depending on their position in the joint and the loading situation. The steel shear keys were connected to the element by bolts while the concrete shear keys were casted together with the element to increase the shear strength. For the model specimens, a unique test set-up has been developed allowing that one element is movable while the other one is fixed, resulting in an axial, bending and shear deformations in the joint respectively. Only horizontal loading was applied in this experiment. The axial load and the bending moment were provided by a set of four hydraulic jacks which are controlled independently while the shear force was applied by an additional jack. Further, a testing procedure was elaborated, consisting of three loading protocols, namely axial compression, compression-bending moment and compression-shear loading cases. For the axial loading case, the hydraulic jacks first provided the gradually increasing axial force then the jacks were unloaded. For the compression-bending case the axial force was applied to an specific value to simulate the initial water pressure in the joint and then a bending moment was imposed. The immersion joint was allowed to rotate, resulting in the occurrence of an opening of the joint. For the shear loading cases, an axial force was also applied at the beginning followed by a reciprocating shear force with increasing amplitude. The shear force was increased until all the shear keys failed. During the experiments, measurements were executed after each successive increase of the load or displacement, comprising axial and shear deformations. Regarding the axial and flexural performance of the joint, the compression-release curve and the bending moment-rotation curves with different levels of axial forces were obtained. Through the obtained load-deformation curves, both the axial stiffness and the flexural stiffness of the joint were derived for use in practice. During this testing cases, a hysteretic loop was observed in both axial and flexural behavior of the joint, indicating that the rubber seal is not perfectly hyper-elastic material as assumed and energy-dissipation did occur. Moreover, an asymmetric bending behavior was observed as the axial force increased. The static and dynamic behavior of the joint were investigated by imposing static and dynamic shear loading respectively. The static and dynamic load-displacement curves of the joint with different loading scenarios were obtained. Accordingly, the static and dynamic shear stiffness of the joint were derived as well. A comparison was made between the static and dynamic shear performance of the joint. The failure behavior of the joint with the steel shear keys and concrete shear keys were investigated by applying reciprocating shear loads with increasing amplitude under a constant axial force. The failure mode of the joint with these two types of shear keys as well as the shear capacity of the joint were obtained. Both series of test results show that the shear keys were not activated at the same time, resulting in a difference between the design shear capacity and experimental one. Finally, a significant contribution of the rubber seal in the shear direction was found, indicating that the shear behavior of the rubber seal should be taken into account in the design procedure. A general literature study with respect to seismic mitigation methods was performed serving as a starting point for the application to immersion joints. To achieve this, a buckling energydissipation device (BEDD) on the basis of the Buckling Restrained Brace (BRB) was introduced and a detailed design procedure for the seismic mitigation device in the joint was provided supposing that the device can work in coordination with the joint in such a way that the maximum energy dissipation is reached. In order to validate the design procedure, a largescale experiment was conducted on an immersion joint subjected to compression-bending moment cases. The bending moment-rotation curves of the joint with seismic mitigation devices as well as the hysteretic performance of the device itself were obtained through axial transducers and strain gauges on the device. It was experimentally proved that the hysteretic performance of the joint was enhanced by using the seismic mitigation device though the performance of the device itself did not meet the expectation. However, it indicated that such application of the seismic mitigation method has a high potential in energy dissipation in immersion joints. In the presented PhD thesis, the mechanical behavior of the joint subjected to axial, flexural and shear loadings and the seismic mitigation method for immersion joints have been studied comprehensively in an experimental way. As the first attempt ever on such issue, the results gained from these investigation give clear insights on the behavior of joint under different loading scenarios. The obtained stiffnesses can be used in further numerical analyses. The proposed seismic mitigation method for immersion joints is shown to be feasible not only to enhance the seismic performance of the joint but also to provide an additional way for energy dissipation of immersed tunnels. The material characteristics of the rubber seal are found to play a much more important role than what is expected from conventional design."],"dc:format":["application/pdf"],"dc:identifier":["https://biblio.ugent.be/publication/8563084","http://hdl.handle.net/1854/LU-8563084","urn:isbn:9789463550949","https://biblio.ugent.be/publication/8563084/file/8563093"],"dc:language":["eng"],"dc:publisher":["Ghent University. Faculty of Engineering and Architecture"],"dc:rights":["info:eu-repo/semantics/openAccess"],"dc:subject":["Technology and Engineering"],"dc:title":["Experimental assessment of the mechanical behavior of immersion joints and a seismic mitigation method in immersed tunnels"],"dc:type":["dissertation","info:eu-repo/semantics/doctoralThesis","info:eu-repo/semantics/publishedVersion"]},"updated_at":"2026-07-24T02:23:03Z"}