The characteristics of the reinforced soil interface are the basis of the design of the reinforced structure. The method of stitching transverse rib geotextile reinforcement is a new reinforcement technology for the improvement of traditional geotextiles. It improves the interaction of the reinforced soil interface through three-dimensional reinforcement and gives full play to the advantages of high strength of geotextiles. In order to study the influence of the number and height of transverse ribs on the characteristics of the reinforced soil interface, the discrete element numerical simulation of the direct shear test was carried out according to the indoor test results, and the mechanical response of the reinforced soil interface under different number and height of transverse ribs was analyzed from the macroscopic and mesoscopic parameters. The results show that the shear strength of the reinforced soil interface can be significantly improved by stitching the transverse rib geotextile. The shear stress-displacement curve is mainly divided into two parts: linear growth stage and stable stage. With the increase of the number and height of the transverse ribs, the overall shear strength of the geotextile increases. When the ratio of the height of the transverse ribs to the thickness of the soil layer is 0.5, the shear strength of the interface is significantly improved and the strain value on each transverse rib is more uniform. Therefore, it is recommended that the height of the transverse ribs is 0.5 times the reinforcement spacing in practical application. With the increase of the number of transverse ribs, the quasi-cohesive force increases obviously and the quasi-friction angle changes little. With the increase of the height of transverse ribs, the quasi-friction angle increases obviously and the quasi-cohesive force changes little. In the process of direct shear test, the strain of the paving part of the geotextile and the strain on the transverse rib increase with the increase of the number and height of the transverse ribs. The maximum strain is at the joint of the two. The strain of the first transverse rib is the largest and the fastest increase, which makes the joint of the transverse rib become the key of the whole system. Therefore, the height, setting position and stitching strength of the first transverse rib should be paid attention to in practical application. This study can provide a reference for the engineering application and further research of geotextiles as reinforcement materials.

To study the effect of anchor length on anchorage effect of weak rock masses in a deep tunnel, the indoor similar model tests were carried out on failure test of rock masses during the excavation opening. The variation characteristic on the failure, displacements and stress of the rock mass after excavation were analyzed comparatively under three conditions (without anchors, with short anchors and long anchors).In the loading test, the failure process of rock mass around the opening shows that the failure process of surrounding rock occurs first at the side wall, then the arch waist and the arch collapse. The surrounding rock in the arch roof after reinforcing rock bolts forms the effect of strengthening beam because of the reinforcement of rock bolts, which leads to the significant increase in the maximum settlement and failure load of the arch roof. The length of rock bolts need to pass through the plastic loosening zone of the arch roof. If the length of anchor rod is not enough to anchor the whole plastic loosening zone, there will be stratification between the anchored surrounding rock and the unanchored surrounding rock. Based on the theory of homogenization strength of rock mass, the short bolt mainly increases the effective support force of surrounding rock at shallow tunnel wall, thus improving the strength of surrounding rock, and the long bolt (cable) can regulate the stress in the elastic zone of deep surrounding rock. Therefore, the combination of the long bolt (cable) effectively regulates the stress state of surrounding rock.

Bonding with existing concrete is one of the important application situations of self-compacting concrete. With the aim of investigating the bonding characteristics between DSSC (desert sand self-compacting concrete) and other existing concrete, the bond-casting test, bonding interface splitting tensile strength and sand-filling method was used to determinate the failure mode and analyze the influence of concrete type and interface treatment method on the bonding characteristics between old and new concrete. Scanning electron microscope was used to photograph the micro-morphological characteristics of the bonding interface and determinate the distribution of gap width. The results show that the bonding performance is stronger when the linear grooving is consistent with the loading direction. Compared with linear groove cutting, the drilling interface is more efficient in interface efficiency and bonding strength. Low water-to-cement ratio reduces the bond interface gap. The effect of desert sand on the reduction of the bond interface gap is more significant with low water-to-cement ratio.

In order to reduce the panalkalisation of alkali-inspired materials for repair, the inhibition of panalkalisation of alkali-inspired materials for repair was investigated by means of surface spraying of admixtures, doping of glass powder, and doping of red mud. The inhibition mechanism was also analysed by scanning electron microscopy, nitrogen adsorption analysis and super depth of field image analysis. The results show as follows. After brushing PNC401 waterproof coating or organosilicon waterproofing agent on the surface of mortar specimen, the amount of alkali flooding is reduced by 61.3% and 26.7%, respectively. The dosage of glass powder and red mud within 15% meets the requirements of the performance of the repair mortar. The amount of alkali flooding was reduced by 60.7% and 52.0% after doping of 15% glass powder and red mud, respectively, and the number of pore spaces inside the mortar was less, no obvious cracks were produced, which reduced the dissolution of alkaline ions. The number of pores inside the mortar is less, and there is no obvious crack, which reduces the dissolution channel of alkaline ions, and it has a good inhibition effect on the alkaline flooding of alkaline stimulating materials for repairing.

Utilizing phase change materials and carrier materials to prepare phase change particles, replacing concrete aggregates for the production of phase change concrete, represents a novel technique for enhancing the durability of concrete in cold regions. In order to investigate the correlation between the compressive strength of PCC and its pore characteristics, a novel type of phase change particles with cement-encapsulated, named EPC₁₄, was prepared by using n-tetradecane (C₁₄) and EP (expanded perlite) as raw materials. Subsequently, phase change concrete (PCC-EPC₁₄) was prepared by replacing fine aggregates at an equal volume. The PCC-EPC₁₄s underwent 50, 100, 150, and 200 freeze-thaw cycles. Then, uniaxial compression tests and nuclear magnetic resonance tests were uesd to test the compressive strength and pore characteristics of the PCC-EPC₁₄s. Finally, the fractal dimension of the PCC-EPC₁₄ was calculated using fractal theory, and the relationship between compressive strength and fractal dimension was analyzed. The results show that the optimal volume replacement ratio of phase change particles to fine aggregates is 20%. At this ratio, the PCC-EPC₁₄(20%) exhibites the maximum NMR (nuclear magnetic resonance) fractal dimension, minimum porosity, and maximum compressive strength after 200 freeze-thaw cycles. Additionally, a proportional relationship is observed between compressive strength and NMR fractal dimension, while an inverse relationship is found with relaxation time signal area.

In order to study the influence of overlying load on the internal deformation of soil outside the foundation pit, a transparent soil test chamber with controllable deformation mode of retaining structure was designed and combined with particle image velocimetry technology to analyze the influence of different deformation modes of retaining structure and overlying load on the internal deformation of soil. The reliability of the test results was verified by comparing the data obtained from the transparent soil test with the prediction curve and the engineering example. The results show that the overlying load has a significant effect on the displacement field of the soil outside the pit. Increasing the overlying load or reducing the distance between the overlying load and the retaining structure will make the influence area of soil displacement outside the pit expand to the deep soil layer, and the maximum vertical settlement and horizontal displacement will also increase. The soil depth of the soil outside the cantilever type and the convex type is significantly affected by the overlying load pressure and distance. The displacement of the upper soil is significantly affected by changing the pressure and distance of the overlying load in the cantilever deformation mode, but the displacement of the middle and lower soil is more significantly affected by changing the pressure and distance of the overlying load in the convex deformation mode. Compared with reducing the distance of the overlying load in the same proportion, increasing the overlying load has a greater impact on the displacement. It can be seen that in the actual project, it is necessary to combine the local building distribution with the underground engineering environment, and take appropriate measures to avoid the most unfavorable deformation mode of the retaining structure.

With the gradual formation of “trunk-branch” linkage multi-level air cargo transportation system, the problem of low turnover efficiency of airport cargo is becoming more and more prominent, and the “trunk-branch” linkage efficient cargo allocation methods have become one of the key technologies to solve the above problems. An integer programming linkage allocation model was established with the maximum loading rate under “trunk-branch” linkage as the optimization objective while simultaneously satisfying constraints such as cabin position, cabin size, center of gravity, and weight for both trunk and branch aircraft. This model was applied based on genetic algorithms to optimize the cargo allocation between the B757-200 trunk aircraft and the ARJ21-700F branch aircraft. It was found that the average loading rate of “trunk-branch” linkage allocation was increased by 5.45% to 72.05% compared with sequential allocation.By demonstrating that the proposed “trunk-branch” linkage allocation method in this study can significantly increase the overall cargo loading capacity, and thus effectively improving the efficiency of cargo turnover at airports, laying a theoretical foundation and providing technical support for the safe and efficient development of the “trunk-branch” linkage multi-level air cargo transportation system.

The anti-corrosion maintenance workload of railway fasteners and bolts in China is large, and the cost of manual lubrication operation is high, the efficiency is low, and the labor intensity is high, and there are problems such as operation safety risks and ballast pollution. In order to solve this series of problems, an automatic lubrication device based on PLC(programmable logic controller)control that can automatically lubricate fasteners and bolts on railway tracks was developed to realize the efficiency, intelligence and automation of the construction process. Optimize the design of the equipment’s traveling mechanism, lubrication system, fastener bolt identification and sensing device, control system, etc. The adjustable spraying structure was innovatively designed to realize the oil coating operation of different types of tracks, and the sensor device that can adapt to the change of the height and position of the rail fastener bolts was innovatively designed, so as to realize the accurate identification of the track fastener bolts with different height distribution. According to the characteristics of anti-rust grease, the quantitative atomization technology of the device was analyzed and optimized. Delta’s DVP ES2-24MR PLC is connected to an external actuator, which processes data through the PLC to control the corresponding sensors in real time, and uses compensation algorithms to achieve accurate control of the equipment oil coating operation. The experiment shows that the automatic lubrication device shortens a large number of construction periods, solves the pollution phenomena such as inaccurate lubrication, oil dripping and wire pulling of the existing mechanical lubricating machine, and the device can effectively guarantee the quality and safety of the lubrication operation, effectively improve the construction efficiency and reduce the construction cost.

In order to solve the problem of real-time monitoring and accurate prediction of structural deformation of platform doors on high-speed railway lines, an artificial intelligence-based neural network method was used. Structural deformation data of platform doors, involving 210 different conditions of train length, blocking ratio, installation distance, and speed, were selected as training samples for the network model. Two neural network models, CNN(convolutional neural network) and K-Fold(K-Fold cross-validation) optimized GRNN(general regression neural network), were used to establish predictive models for platform door structural deformation under different working conditions of high-speed railways. These models were compared and verified with the remaining sample data. The research shows that both models effectively predict the operation and maintenance data of railway platform door structures. The K-Fold optimized GRNN model is superior to the CNN model in prediction accuracy. The Mean Square Error of the K-Fold optimized GRNN model is maintained within 0.22, and theRoot Mean Square Error is within 0.27, which is at the leading level in the field. The K-Fold optimized GRNN model better predicts the structural deformation of platform doors when trains pass, providing data references for the design and maintenance of high-speed railway platform doors.

In response to the common problem of secondary lining cracking in double-arch tunnel without middle drift, how to improve its mechanical characteristics to ensure the safety of tunnel construction and operation is the focus of this study. Based on the arch section of Yijin Expressway Huangjiaoping Tunnel Project, numerical simulation method was adopted, the influence of support parameters such as the thickness of the initial support, the spacing of the steel frame, and the thickness of the secondary lining of the advanced tunnel on the displacement of surrounding rock, the mechanics characteristics of the initial support and the secondary lining of the advanced tunnel were deeply studied, and reasonable and optimized support parameters were proposed. The results show that as the thickness of the initial support increases or the spacing of the steel frame decreases, the displacement of the surrounding rock of the advanced tunnel and the principal stress of the secondary lining continue to decrease, and the principal stress of the initial support continues to increase. Among them, the maximum tensile stress of the secondary lining decreases significantly. When the thickness of the initial support is 0.28 m or the spacing of the steel frame is 0.5 m, the maximum tensile stress decreases by about 15% compared with the most unfavorable condition. As the thickness of the secondary lining increases, the displacement of surrounding rock, the principal stress of the initial support and the secondary lining of the advanced tunnel decrease significantly. Compared with the thickness of the secondary lining of 0.7 m and the thickness of the secondary lining of 0.5 m, the maximum tensile stress of the secondary lining is reduced by 23.8%. Therefore, moderately increasing the thickness of the initial support or decreasing the spacing of the steel frame or increasing the thickness of the secondary lining can effectively improve the stress of the secondary lining. It is suggested that the thickness of the initial support of the advanced tunnel should be 0.28 m, the spacing of the steel frame should be 0.5 m, the corresponding steel frame type is I22b, and the thickness of the secondary lining should be 0.7 m under the shallow buried state of V-class surrounding rock.