A semantic segmentation-based method for defect segmentation on thin strip cast and rolled steel plates was proposed to accurately and quickly identify surface defects. Firstly, defect images from the production line were annotated using Labeling software to create a defect segmentation dataset. Secondly, a TransUNet network model was established to recognize and segment surface defects, integrating an optimized DANet dual-attention fusion network to enhance model segmentation performance. Finally, comparative experiments between the improved model and other segmentation models were designed. The feasibility and effectiveness of the proposed method are verified through analysis of experimental results and evaluation metrics. The experiments demonstrate that the improved network achieves a segmentation accuracy of 96.85%, an average intersection over union of 96.99%, and a similarity coefficient of 92.98% for foreign object defects on thin strip cast and rolled steel plates, respectively increasing by 1.19%, 0.61%, and 0.63% compared to the TransUNet network. Additionally, the improved network achieves a segmentation accuracy of 92.86% on the publicly available hot-rolled strip steel defect dataset, indicating its versatility and providing technical guidance for intelligent detection of surface defects on steel plates.

Aiming at the poor performance of existing algorithms in solving large-scale ship path planning problems and the lack of consideration of marine environmental factors such as eddies, a ship path planning method based on punishment pheromone ant colony optimization was proposed. Firstly, three evaluation functions were designed for the planned path: length, risk and heading. Secondly, ACO(ant colony optimization) algorithm inspired by reinforcement learning was designed to search the optimal path, which adds punishment pheromone to the traditional guidance pheromone, which can prevent ants from conducting ineffective searches. Finally, the simulation experiments of the improved algorithm under static environments demonstrate that the proposed algorithm is superior to traditional ACO, jump point search algorithm, and bi-directional search improved ACO in terms of path length, risk value and turn accumulation angle. Compared to the best metrics among these three algorithms, proposed algorithm still achieves a significant improvement in path length reduction of 6.1%, risk value reduction of 5.6%, heading accumulation angle reduction of 78.6%, and iteration number reduction of 53.3%. Especially when the mesoscale eddies and water flow are introduced, the proposed algorithm can still plan a more suitable path for ship navigation, which has positive application significance.

The evaluation of grouting defects in precast beam grouting sleeves has long been a focal point of scholarly research, with the impact of horizontal defects on performance surpassing that of end and vertical defects. Aiming at the problem of horizontal grouting defect evaluation, the active excitation signal of AST (auto sensor test) and PLB (pencil-lead breakage) function built in acoustic emission instrument was studied, combined with horizontal sleeve grouting fullness test.Through parameter analysis and fast Fourier transform, changes in acoustic emission wave velocity, energy, count and waveform parameters are examined at filling degrees of 50%, 60%, 70%, 80%, 90% and 100%. Furthermore, the correlation between acoustic emission energy, count parameters and main frequency amplitude with grouting fullness was established. The results show that when the excitation source is AST, the acoustic emission energy, count and the main frequency amplitude of its waveform show a good negative exponential correlation with the increase of grouting sleeve fullness, and the combination of the relational equations allows for quantitative acoustic emission analysis and evaluation of grouting fullness of horizontal grouting sleeves.

In order to improve the efficiency of finite element analysis and reduce memory consumption, the storage algorithm of the overall matrix was studied. The constraints were uniformly processed as matrix partitions at the element level. Subsequently, taking the stiffness matrix as an example, the distribution pattern of non-zero elements under the constrained condition was determined. A calculation method and corresponding formulas suitable for the number of non-zero elements in the stiffness matrix of two-dimensional and three-dimensional finite elements were proposed, and the correctness was verified. The correspondence between one-dimensional equal bandwidth storage and the original square matrix address was deduced, and it was applied as an auxiliary array in the process of integrating the overall matrix in CSC format, which has improved the efficiency of the overall matrix assembly and avoided the difficulty of node numbering optimization. Finally, the correctness and practicability of the proposed algorithm were verified by using thefour-span single-line girder bridge in the Changdao section of the Fangshan Line in Beijing. The results show that the overall matrix assembly time is reduced by 30%, the storage space is saved by more than 68%, and the calculation efficiency of linear equations is improved by more than 71% while ensuring the calculation accuracy.

In order to accurately select the Copula function to simulate the mutual correlation between inclination and dip of jointed rock mass structural plane, the Copula function method to simulate the occurrence of jointed rock mass structural plane under different fitting indexes was proposed. The optimal Copula function was determined by using the least square Euclidian, AIC information criterion and BIC information criterion, and the optimal edge distribution type of the observed occurrence data of the structural plane was determined by Matlab software. At the same time, Monte Carlo sampling method was used to automatically generate simulation data, and the data was imported into Dips software for visualization processing, and the erP projection map of occurrence was obtained. The difference between the measured dip and inclination data and the simulated data determined by Copula function under different fitting indexes was compared. Finally, the validity of the method is tested based on engineering cases. The results show that different fitting indicators will produce different Copula functions, and there will be great differences in the effectiveness of simulation occurrence. Improper fitting indicators may lead to the selection of inaccurate Copula functions, so that the model can not accurately capture the relevant structure and features of the data. Inappropriate fitting indexes may lead to large errors between the fitting model and the real data, which will decrease the predictive ability and interpretation ability of the model. In this case, it is shown that the Gaussian Copula function selected under the fitting index of least square Euclidene values has the best fitting effect on the measured data. This research will help to select the appropriate fitting index when using Coupla function.

Deformation law is of significant for ensuring the safety of structures and environment during the large diameter shield tunnelling. Particularly for shallow and large diameter shield tunnelling in soft soil, the mutual coupling of high compressibility and low shear strength of soft soil and low overburden load under shallow burial conditions as well as the unloading effect of large excavation will lead to a more complex construction deformation mechanism. Hence, the characteristics of structure vertical deformation, structure convergence deformation and surface deformation caused by shallow and large diameter shield tunnelling in soft soil and their mechanism were studied, based on the dynamic deformation monitoring of a shallow buried large-diameter shield tunnel of Shanghai Suburban Railway Airport Link Line. The results show that the ephemeral demarcation times for different deformation types were closely related. The vertical deformation of the structure can be divided into 4 stages: prior uplift, fluctuating uplift, continuous uplift, and relative stability. The structure convergence deformation can be divided into 3 stages: fluctuating convergence, continuous convergence, and stable convergence. And there are 3 stages, perturbation settlement, rapid consolidation, and relative stability in the vertical deformation of the axial surface. There are significant differences in the vertical structure deformation caused by uneven distribution of additional pressure on the tunnel structure. The maximum vertical surface deformation in the tunnel axis would exceed the warning value and the final settlement deformation would be approximately 84.3% the maximum deformation. The width of the surface sinkhole and location of the maximum settlement are closely related to the depth-to-diameter ratio, but the “swell ridge” distribution would be evident when the depth-to-diameter ratio is relatively large. In about 21~50 d after the excavation construction, the amplitude of structure vertical deformation, structure convergence deformation and surface vertical deformation is significant, and the deformation trend is relatively explicit, which is the key stage to improve the deformation control and remediation effect. The findings of this study are intended to serve as a significant reference for the control of structure deformation and environmental safety protection of shallow and large diameter shield tunnelling in soft soil.

The construction decision of special geological area is very important and complicated. The uncertainty of geological conditions will directly affect the selection and implementation of construction scheme. In order to solve the non-equilibrium problem among the “five control” objectives (time limit, cost, quality, safety and environmental protection) of the bridge construction scheme in the complex special geological area of Southwest China, the network planning technology and BIM(building information modeling) were combined. BIM visualization technology, fuzzy set theory and GRA(grey correlation analysis) were integrated into the optimization of bridge construction schemes in complex special geological areas. HFMD(hybrid fuzzy multi-attribute decision-making model) based on duration-cost-quality-safety-environmental protection was established, and a visualization system of construction process was constructed by using Python and BIM technology. Assisted managers to make decisions, and the result met the “five control” index comprehensive optimization scheme, and the construction period was advanced by 10 days, and the cost was reduced by 3.1%, which proved the practicability and effectiveness of this model A and method. It provides a reference for the decision of bridge construction scheme in complex special geological area.

Cone-shaped hollow foundation is a new form of onshore wind power foundation, which has the advantages of low steel and concrete consumption and reduced waste soil generation during excavation of the foundation pit, compared with the traditional gravity foundation. In order to investigate the bearing characteristics of a cone-shaped hollow foundation under combined loads, a numerical simulation was carried out to investigate the influence of the ratio of the diameter of the top plate to the diameter of the bottom plate on the combined bearing capacity and damage mode of the foundation when the volume of the foundation is held constant. The results demonstrate that when the ratio of the diameter of the top plate to the diameter of the base plate is 6, the vertical ultimate bearing capacity of the cone-shaped hollow foundation is 100% higher than that of the same volume gravity circular foundation, and the moment ultimate bearing capacity is 60% higher. The failure envelopes of different diameter ratios of the cone-shaped hollow foundation can be described by a curve under different combination loads, and the expressions of the failure envelopes of different combination loads are proposed. The failure envelopes of gravity circular and cone-shaped hollow foundations under combined horizontal and bending moment loads show obvious asymmetry, with opposite directions of eccentricity. When the horizontal and bending moment loads are in different directions, the circular foundation has higher bearing capacity. When the horizontal and bending moment are in the same direction, the cone-shaped hollow foundation has higher bearing capacity. The cone-shaped hollow foundation shows a better combination of load-bearing capacity, which can be provided for the super-large single installed capacity wind turbine.

In order to improve the engineering quality problems such as pavement cracking caused by excessive subgrade deformation caused by road use of collapsible loess, alkali activated sustainable material industrial solid waste GGBS(ground granulated blastfurnace slag was used to reinforce and improve the collapsible loess. The influence of different dosage of curing agent on the basic physical properties, mechanical characteristics, permeability and collapsibility of the solidified loess was discussed, and the improvement mechanism of the curing agent was expounded from the microstructure. The results show that the liquid plastic limit of solidified soil increases and the plasticity index decreases. The optimum moisture content decreases first and then increases with the increase of the content of curing agent. The corresponding maximum dry density increases first and then decreases. The maximum dry density of 10% of the content is 1.80 g/cm³. The strength of loess is improved by the curing agent. The strength increases linearly with the increase of the content. The content of 20% curing agent can increase to 2.3 MPa, while the C_BR value of 6% curing agent can increase to 8.3%. The permeability coefficient decreases with the increase of the content of the curing agent. When the content of the curing agent is 10%, the permeability coefficient can be reduced to below 10^-7 m/s, and the collapsibility coefficient decreases with the increase of the content of the curing agent. When the content of the curing agent reaches 6%, the solidified soil becomes non collapsible soil. The comprehensive performance shows that 10% of the content is the optimal amount for road use. In terms of microscopic morphology, the curing agent has changed the contact mode of loess particles. The loess particles have changed from point-surface contact to surface-surface contact. The pore size has changed from middle pore and macropore to middle pore, and the number has decreased. Macropores are filled. Compared with remolded loess, the macropores and mesopores in 10% stabilized soil have decreased from 33.0% and 31.5% to 3.9% and 14.8%, respectively, 29.1% and 16.7%, The fractal dimension of pore distribution decreases from 1.12 to 0.96. Through alkali activated GGBS to solidify collapsible loess, the collapsibility of loess is improved, and its performance has a good road use prospect. This study can provide theoretical basis and practical reference for the consolidation of collapsible loess.

In order to study the hydrothermal characteristics of the sand soil replacement subgrade, the method of indoor freeze-thaw cycle test was used to investigate the hydrothermal changes at different depths of the sand samples with different gradations, and to compare and analyze the effects of coarse sand and fine sand on the silty clay in the lower layer. The results show that during the freezing process, the soil close to the cold end will have a “water increase phenomenon”, and the silty clay is more prone to water migration than the sandy soil. Both the replacement of fine sand and the replacement of coarse sand can inhibit the cooling of the lower silty clay and reduce the freezing depth, so as to avoid the frost heave and thawing of the subgrade. Compared with coarse sand, the replacement of fine sand has a better effect on inhibiting the downward transmission of negative temperature at the top, and the replacement of fine sand is more conducive to maintaining temperature stability. The freezing depth of the replacement of fine sand is smaller than that of the replacement of coarse sand, which is more conducive to inhibiting the frost heave of the subgrade soil and maintaining the internal water stability. The freezing characteristic curve of soil and the thawing characteristic curve of soil do not coincide, and the freeze-thaw characteristic curve of replacement fine sand is least affected by temperature at the interface of replacement. It is concluded that the replacement of sand can effectively avoid the occurrence of frost heave phenomenon of subgrade, and the effect of replacing fine sand is better than that of coarse sand.