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The portal section of mountain tunnels usually suffers severe damage during earthquakes. The purpose of this paper is to investigate the seismic performance of the combined system of anchor rod and isolation layer in the portal section of the mountain tunnel. The numerical model was established based on the actual terrain of the engineering site and included the tunnel pillar portal structure, horizontal seismic wave input, and absorbing boundary conditions. Four cases were considered: without measures, anchor rod, isolation layer, and combination of anchor rod and isolation layer. Comparative analysis of the dynamic response and seismic performance of the structure under seismic action for each case. The results show that: (1) The combination measures reducing the maximum peak acceleration of the tunnel pillar portal and lining to 0.33g and 0.36g, respectively, achieving acceleration reduction rates of 30% and 36.8%; (2) The combination measures increases frictional resistance through anchor rod, providing restraint and support to the surrounding rock, and the isolation layer further mitigates the interaction between the surrounding rock and the lining, reducing the stress on the lining. This synergy reduces the maximum relative displacement of the tunnel portal pillar by 43.7% to 9.4mm, and the lining by 58% to 7.8mm; (3) The combination measures reduce the maximum peak principal stress of the lining to 1.48MPa, achieving a stress reduction rate of 68.23%. Effectively enhancing the seismic performance of the tunnel and reducing damage and failure. [ABSTRACT FROM AUTHOR]

Semi‐rebonded periclase‐chromite refractories are commonly utilized in the working lining section of the molten pool in oxygen‐enriched top‐blowing furnaces for nickel production. Its resistance to nickel slag corrosion determines the safety and service life of the melting furnace. The composition of nickel slag influences the corrosion resistance of semi‐rebonded periclase‐chromite refractories. By comparing and analyzing specimens corroded by primary and modified nickel slag, the influence mechanism of w(CaO)/w(SiO2) variations on corrosion resistance of semi‐rebonded periclase‐chromite refractories was clarified. The results show that a spinel isolation layer is preferred to form at a lower w(CaO)/w(SiO2) ratio (< 0.576) and enhance the corrosion resistance of semi‐rebonded periclase‐chromite refractories. As the ratio increases, the slag viscosity falls and the corrosion products contain larger levels of Ca3Cr2Si3O12 and Ca3MgSi2O8, which prevent the creation of the isolation layer and establish a conduit for Ca2+ and Si4+ transport and reaction into the interior of the refractory. [ABSTRACT FROM AUTHOR]

The corrosion behavior and mechanism of nickel slag on semi‐rebonded magnesia‐chrome brick are investigated. The variations in the specimens before and after corrosion were studied using microstructure, phase composition, and thermodynamic simulations. The results reveal that at high temperatures, the metal oxides in nickel slag easily react with Cr2O3 to generate Cr‐spinel, and the isolation layer forms a continuous phase on the surface of the refractory. The appearance of the isolation layer causes the nickel slag corrosion process on semi‐rebonded magnesia‐chrome brick to shift from direct to indirect corrosion controlled by ion diffusion, effectively blocking the continuous penetration of Ca2+ and Si4+ in the slag inside the refractories. As a result, the semi‐rebonded magnesia‐chrome brick resists nickel slag corrosion extremely well. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Masonry structures are frequently constructed in developing countries because of their affordability and ease of construction, even though they are vulnerable and perform poorly during earthquakes. Experimental and numerical studies were carried out to determine the optimum thickness of the isolation layer for a recently developed, low-cost seismic isolation system known as the Reinforced-Cut-Wall (RCW). The parameters of the isolation layer were optimized during the experimental and numerical investigations using hollow concrete blocks. Quasi-static cyclic tests were performed on a 1:3 reduced-scale brick masonry wall incorporating the RCW isolation scheme, validating the better performance of the proposed isolation technique. [ABSTRACT FROM AUTHOR]

The establishment of an isolation layer in submarine mining has been a persistent challenge. In the context of this research, we conducted a similarity simulation test to preliminarily assess the interaction between the thickness and extent of the isolation layer. Subsequently, we introduce an innovative approach that integrates fractal theory and the Bonded Block Model (BBM) to simulate undersea isolation layer mining. The validation of this method relies on on-site borehole scanning and displacement monitoring, which depict the intricate fractal evolution of fractures and predict the optimal thickness of the isolation layer. Our findings affirm the robustness and validity of this method. Evaluation of the fractal dimensions of fractures reveals that a critical threshold of 1.7 is essential to prevent structural failure of the isolation layer, while a limit of 1.5 is necessary to avoid significant water ingress. Remarkably, the correlation dimension of the settlement time series closely aligns with the fractal dimension of the fractures, underscoring the feasibility of ensuring the safety of isolation layer mining through real-time settlement monitoring. [ABSTRACT FROM AUTHOR]

The paper presented a novel analytical solution to evaluate the seismic‐induced stresses and displacements of tunnels covered by an isolation coating layer subjected to SH waves. The solution is derived based on the assumptions that the ground, isolation coating layer, and liner are linear elastic and in steady‐state motion. The analytical solution is obtained using the Bessel‐Fourier series. Comparisons are made between the seismic responses of tunnels obtained using the proposed analytical solution and those of the simulation results from the FEM software ABAQUS. Additionally, the proposed solution is also compared with the known degraded solution from the literature to validate its accuracy. The influence of various key factors, such as the Young's modulus ratio between the coating layer and the ground, the thickness of the coating layer, and the relative stiffness between the ground and the liner, on the seismic response of tunnels are investigated using the proposed analytical solution. [ABSTRACT FROM AUTHOR]

The use of isolation layer structures has been a proven and effective method in reducing the seismic dynamic response of tunnels. It is considered a crucial measure in enhancing the seismic capacity of tunnels. This paper focused on the Xianglushan Tunnel Project and investigated the key factors affecting the glass fiber reinforced concrete (GFRC) isolation layer through shaking table tests. The research analyzed the seismic dynamic response characteristics of the lining under varying fiber content, isolation layer thickness, and seismic intensity. According to the test results, the GFRC isolation layer is more effective in reducing the acceleration and strain response of the lining compared to the rubber isolation layer, indicating a superior isolation effect. The shock absorption effect of the GFRC isolation layer is affected by its fiber content. The best effect is achieved when the isolation layer thickness and lining thickness are in the ratio of 1:1 and the GFRC isolation layer contains 0.9 % glass fiber. The thickness of the GFRC isolation layer has an optimal interval, which is directly related to the glass fiber content. The effectiveness of the GFRC isolation layer in reducing seismic impact decreases as the intensity of the earthquake increases. While the GFRC isolation layer cannot alter the way in which the lining deforms or fails during an earthquake, it can help reduce the seismic dynamic response of critical parts of the lining.

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Quick water seepage in sandy soils results in a serious restriction for ecological restoration, becoming a worldwide urgent research issue in arid areas. Search for practical solutions are focused on reserving the limited rainfall into topsoil layer to meet plant water demand. Based on fieldwork, this study evaluates the blocking effects of Pisha sandstone on soil water leakage, by inserting sandstone layers in the different soil depths (10–15 cm, 20–25 cm, 30–35 cm), which act as isolation layers within the sandy soil. Results showed that the inserted Pisha sandstone layers significantly decreased the soil water infiltration rates at the different stages and cumulative infiltration. The inserted sandstone layer at the depth of 10–15 cm presented the highest permeability resistance, and its initial infiltration rate, stable infiltration rate and average infiltration rate decreased by 102.42 mm h−1, 144.30 mm h−1 and 132.79 mm h−1, respectively. Meanwhile, the soil water content in the 5–10, 20–25, and 30–35 cm soil layers increased by 2.17%, 2.20%, and 1.37%, respectively, due to the inserted Pisha sandstones. This experimental study proves that the insertion of Pisha sandstones effectively hinders the downward penetration of soil water in sandy soil. These findings provide a new alternative for an effective solution of the fast water leakage problem of sandy land.

The establishment of an isolation layer in submarine mining has been a persistent challenge. In the context of this research, we conducted a similarity simulation test to preliminarily assess the interaction between the thickness and extent of the isolation layer. Subsequently, we introduce an innovative approach that integrates fractal theory and the Bonded Block Model (BBM) to simulate undersea isolation layer mining. The validation of this method relies on on-site borehole scanning and displacement monitoring, which depict the intricate fractal evolution of fractures and predict the optimal thickness of the isolation layer. Our findings affirm the robustness and validity of this method. Evaluation of the fractal dimensions of fractures reveals that a critical threshold of 1.7 is essential to prevent structural failure of the isolation layer, while a limit of 1.5 is necessary to avoid significant water ingress. Remarkably, the correlation dimension of the settlement time series closely aligns with the fractal dimension of the fractures, underscoring the feasibility of ensuring the safety of isolation layer mining through real-time settlement monitoring.

Microfracture treatment that is basically relied on stem cells and growth factors in bone marrow has achieved a certain progress for cartilage repair in clinic. Nevertheless, the neocartilage generated from the microfracture strategy is limited endogenous regeneration and prone to fibrosis due to the influences of cell inflammation and vascular infiltration. To explore the crucial factor for articular cartilage remodeling, here we design a trilaminar osteochondral scaffold with a selective permeable film in middle isolation layer which can prevent stem cells, immune cells, and blood vessels in the bone marrow from invading into the cartilage layer, but allow the nutrients and cytokines to penetrate. Our findings show that the trilaminar scaffold exhibits a good biocompatibility and inflammatory regulation, but the osteochondral repair is far less effective than the control of double-layer scaffold without isolation layer. These results demonstrate that it is not adequate to rely only on nutrients and cytokines to promote reconstruction of articular cartilage, and the various cells in bone marrow are indispensable. Consequently, the current study illustrates that cell infiltration involving stem cells, immune cells and other cells from bone marrow plays a crucial role in articular cartilage remodeling based on the integrated scaffold strategy. Clinical microfracture treatment plays a certain role on the restoration of injured cartilage, but the regenerative cartilage is prone to be fibrocartilage due to the modulation of bone marrow cells. Herein, we design a trilaminar osteochondral scaffold with a selective permeable film in middle isolation layer. This specific film made of dense electrospun nanofiber can prevent bone marrow cells from invading into the cartilage layer, but allow the nutrients and cytokines to penetrate. Our conclusion is that the cartilage remodeling will be extremely inhibited when the bone marrow cells are blocking. Owing to the diverse cells in bone marrow, we will further explore the influence of each cell type on cartilage repair in our continuous future work. [Display omitted] [ABSTRACT FROM AUTHOR]

In order to explore the effect of ZrO2 isolation layer on phase composition and microstructure of lanthanum aluminate high emissivity coating, Ca2+ and Fe3+ doped lanthanum aluminate (LaAIO3) powders were prepared using La2O3, AI2O3, CaCO3 and Fe2O3 (all 99% purity) as raw materials via solid phase sintering method according to the stoichiometric ratio of La0.8Ca0.2AI0.8Fe0.2O3. The LaAIO3 and ZrO2 composite coating (LCAFO/ZrO2) were prepared using LaAIO3 powder as the high emissivity infrared ceramic powder radiation agent and ZrO2 coatings with different particle sizes as the isolation layer. The developed coating and the LCAFO (LaAIO3) coating were spread on the surface of bubble AI2O3 bricks for the lining of industrial furnaces, respectively. The coatings were analyzed using XRD and SEM. The results show that LCAFO coating does not react with bubble AI2O3 bricks at 1 200 °C, but they react at 1 400 °C forming LaAl11O18, and the reaction is more sufficient at 1 600 °C. The thickness of the LaAl11O18 layer increases with the temperature rising. When the ZrO2 isolation layer is coated between the LCAFO layer and the bubble AI2O3 bricks, no LaAl11O18 phase exists and no reaction layer appears at 1 400 °C. [ABSTRACT FROM AUTHOR]

Currently, punchout distress in continuously reinforced concrete pavement (CRCP) frequently occurs even if the reinforcement design strictly adheres to specifications. In this study, a new concept called reinforced concrete pavement with large spacing joints (RCPS) is proposed, and a new isolation layer is applied to the RCPS on the basis of laboratory results. Finally, a test road is constructed to verify the rationality of the structure of RCPS. The results show that reducing the friction and bonding strength between the isolation layer and pavement is the key to implement RCPS. The design method of RCPS not only retains the good bearing capacity of CRCP but also overcomes the problem in which the dry shrinkage and temperature stresses of CRCP cannot be released, which leads to punchouts. [ABSTRACT FROM AUTHOR]

Based on a rectangle underground station structure, two-dimensional finite element models are established in this study to explore the effectiveness of different seismic reduction and isolation measures for underground structure, where Davidenkov model is adopted to consider the soil nonlinearity and the underground structure is considered elastic. The performances of the seismic reduction and isolation measures are evaluated by assessing the structure internal force and deformation responses. Depending on the ratio of wave impedance between the isolation layer and the structure, the isolation layers are divided into rigid and flexible types. The effects of the length and elastic modulus of rigid isolation layer as well as that of the thickness and shear modulus of flexible isolation layer are investigated. The results show that the seismic reduction effect of rigid isolation layer is better with the increase of stiffness, and the effect of flexible isolation layer is more obvious with the decrease of stiffness, which are consistent with the classical impedance theory. Furthermore, the middle column of subway station is usually the most vulnerable during seismic shakings, and one viable way to improve its seismic behavior is to reduce the column end constraints. Therefore, different column constraints consisting of swing, hinge, sliding connection and isolation bearing are considered. The numerical results suggest that among the different column end constraints considered, the sliding connection is comparatively more favorable, which can effectively limit the lateral deformation of column while imposing no horizontal reaction force. [ABSTRACT FROM AUTHOR]

Tunnels crossing the soft and hard rock junction suffer severe damages during strong earthquakes. In this paper, elastic-plastic numerical models considering the modified wave, the boundary condition and the monitoring system are established to investigate the seismic performance of the isolation layer in the soft and hard rock junction of the tunnel. The results show that tunnel safety is related to the proportion of soft and hard rocks, where the larger the proportion of soft rock is, the more vulnerable is the tunnel structure to the seismic waves. The maximum principal stress of secondary linings decreases by 50.23%-89.96%, 51.16%-98.95% and 55.98%-97.39%, respectively, when the dip angle of the soft and hard rock interface is 45°, 60° and 75° after the isolation layer is adopted. The seismic effects of the isolation layer with dip angles of 45°, 60° and 75° are 2.45%-121.67%, 13.19%-66.98% and 4.60%-131.83%, respectively. The application of the isolation layer significantly increases the safety of the tunnel crossing the soft and hard rock junction, except for the structure located at the soft-hard rock interface. It is suggested to adopt both isolation measures and structure reinforcements at the structure intersecting the soft and hard rock interface. [ABSTRACT FROM AUTHOR]

This study investigates the effectiveness of the non-smooth semi-active control algorithm on suppressing the vibration performance of a building structure subjected to seismic waves. According to the Lyapunov stability theory, it has bene proven that the non-smooth semi-active control algorithm can achieve a finite-time stability of the vibration relative to the isolation layer of a building structure. Through numerical simulation of two buildings with different parameters subjected to the input of a seismic wave, the vibration conditions of passive control, LQR semi-active control and non-smooth semiactive control are compared and analyzed. The simulation results show that the non-smooth semi-active control algorithm has a better robustness and effectiveness in restraining the impact of earthquakes on the structure. [ABSTRACT FROM AUTHOR]

• Blocking effects of Pisha sandstone on water leakage in sandy land were examined. • Inserted Pisha sandstone in sandy land changed the vertical distribution of soil water. • Inserted Pisha sandstone at 10–15 cm depth caused high permeability resistance. • Inserted Pisha sandstone effectively hindered the downward leakage of sandy soil water. Quick water seepage in sandy soils results in a serious restriction for ecological restoration, becoming a worldwide urgent research issue in arid areas. Search for practical solutions are focused on reserving the limited rainfall into topsoil layer to meet plant water demand. Based on fieldwork, this study evaluates the blocking effects of Pisha sandstone on soil water leakage, by inserting sandstone layers in the different soil depths (10–15 cm, 20–25 cm, 30–35 cm), which act as isolation layers within the sandy soil. Results showed that the inserted Pisha sandstone layers significantly decreased the soil water infiltration rates at the different stages and cumulative infiltration. The inserted sandstone layer at the depth of 10–15 cm presented the highest permeability resistance, and its initial infiltration rate, stable infiltration rate and average infiltration rate decreased by 102.42 mm h−1, 144.30 mm h−1 and 132.79 mm h−1, respectively. Meanwhile, the soil water content in the 5–10, 20–25, and 30–35 cm soil layers increased by 2.17%, 2.20%, and 1.37%, respectively, due to the inserted Pisha sandstones. This experimental study proves that the insertion of Pisha sandstones effectively hinders the downward penetration of soil water in sandy soil. These findings provide a new alternative for an effective solution of the fast water leakage problem of sandy land. [ABSTRACT FROM AUTHOR]

The differential cubature solution to the problem of a Mindlin plate lying on the Winkler foundation with two simply supported edges and two clamped edges was derived. Discrete numerical technology and shape functions were used to ensure that the solution is suitable to irregular shaped plates. Then, the mechanical model and the solution were employed to model the protection layer that isolates the mining stopes from sea water in Sanshandao gold mine, which is the first subsea mine of China. Furthermore, thickness optimizations for the protection layers above each stope were conducted based on the maximum principle stress criterion, and the linear relations between the best protection layer thickness and the stope area under different safety factors were regressed to guide the isolation design. The method presented in this work provides a practical way to quickly design the isolation layer thickness in subsea mining. [ABSTRACT FROM AUTHOR]

Highlights: [•] Dynamic centrifuge tests on square tunnel model with isolation layer. [•] Effectiveness of isolation layer on seismic response reduction is proved. [•] The mechanism of seismic reduction of isolation layer is clarified. [•] Relation between excitation frequency and isolation layer efficiency is revealed. [ABSTRACT FROM AUTHOR]

Spontaneous combustion occurs easily in open-air stacking coal gangue dumps, which leads to serious geological disasters and environmental pollution. To improve the traditional direct soil cover methods of coal gangue dump treatments, a new isolation layer with fly ash and clay soil for preventing spontaneous combustion of a coal gangue dump was developed, which was placed as a cover on the surface of the coal gangue dump and before the topsoil covers. The study area of this research was a slope in the east part of the coal gangue dump of NO.3 Colliery, Yangquan Group. The area was divided to four plots. Each plot was more than 200 m2. Different kinds of isolation layers were applied in each plot. The isolation layers were designed as fly ash (FF), clay (NN), layered fly ash, and clay (FNC) and a mixture of fly ash and clay (FNH). FNC was composed of fly ash first and then clay, and its thickness was 10cm and 20cm respectively. FNH was designed with the proportion of fly ash: clay =1:2, and its thickness was 30cm after being ground twice by 4t rolling. One year after the isolation layers were constructed, the samples were taken from the study area at regular intervals. The result of a dynamic test on the permeability of the samples showed that the utilization of a isolation layer of fly ash and clay before the soil covering could block the air effectively. The permeability of the FF or NN layer was lower than the critical value (0.2×10-9 m2) of the spontaneous combustion at the beginning, however, as time went by, the value of permeability increased, and finally could not effectively block the air. The effect of the mixture of the two materials was better than only one material. The experiment showed that the mixture with the fly ash: clay =1:2 (volume ratio) proportion had the best blocking effect, and its permeability was below 50×10-12 m2. By testing the surface temperature and compaction after one year of revegetation, the result showed that the temperature of the FNC and FNH applied area was more stable with increasing depth which was between 10-15°in the depth of 10~30cm, indicating the good effect of blocking oxygen. The values of compaction of the different layers were increasing sharply with increasing depth, which formed an ideal profile for the vegetation. FF had the highest compaction value. FNC was the second, and the top value of its compaction was about 2 800 kPa in the depth of 30.48-38.12 cm. The compaction value of FNH was changed slightly due to the different depth. This research provides reference data and a method for the configuration of isolation layers for preventing spontaneous combustion of coal gangue dumps. [ABSTRACT FROM AUTHOR]