The structure and materials used in bridge deck pavement layers significantly impact their road performance. To design a pavement layer more suitable for cold regions, the layered modification of pavement materials was optimized based on the principle of layer function design. Firstly, materials for the surface functional layer and overall functional layer were selected using the layer function division, with lignocellulose and polyester fibers as modifiers, respectively. Secondly, the appropriate content of polyester fibers was determined through road performance tests. Finally, the choice of layered materials and appropriate modification methods were established. The results indicate that both the surface functional layer and the overall functional layer should use the same high-viscosity, high-elasticity modified asphalt, with lignocellulose and polyester fibers as modifiers, respectively. This approach avoids differences in thermal contraction coefficients of the layered materials, ensuring coordinated thermal deformation between the pavement layer and the bridge structure, thereby effectively improving the road performance of the asphalt bridge deck pavement. Furthermore, under engineering economic requirements, when the polyester fiber content is 1% of the total mixture mass, the prepared asphalt mixture's high-temperature performance increases by 7%, low-temperature performance by 23%, and water stability by 5%.

To ensure the safety of formwork engineering, and to accurately calculate the lateral pressure of fresh concrete on formwork, the problems of the formulas for lateral pressure of fresh concrete on formwork, provided by the national current standards, were analyzed firstly. Subsequently, based on the basic physical quantities of the international system of units, five key factors affecting the lateral pressure of fresh concrete on formwork were identified, the range of concrete slump was emphatically analyzed. By taking concrete slump as an important factor, it was directly introduced into the derivation. According to the relation between the depth of the concrete from the top of the placement to the point of consideration in the formwork, and the product of the rate of placing concrete in forms and initial setting time, formula for calculating the lateral pressure of fresh concrete on formwork was derived. Finally, the accuracy of the proposed formula was verified by using the experimental data in the literature. The results show that the proposed formula accords with the results of dimensional analysis, and the formula is more accurate in the application range of the formula provided by the national current standards. Moreover, beyond the applicable range of the formula provided by the national current standards, the proposed formula is of high accuracy and is generally safe.

To analyze the main influencing factors and pathways of low altitude travel intention, a structural equation model was constructed based on travel intention model and value risk analysis. The interaction mechanism between travel preference, travel characteristics, perceived value, and perceived risk on low altitude aircraft travel intention was quantified. The path coefficients were solved using unweighted least squares method, and the mediating effects of perceived value, perceived risk, and other factors on travel preference were analyzed. Additionally, a multi group model invariance analysis of individual information such as gender and age on travelers was conducted.Finally, the fuzzy set qualitative comparative analysis (fsQCA) method was used to analyze the configuration of the antecedent variables of travel intention. The results showed that the chi square degree of freedom ratio, RMSEA (root mean square error of approximation)value, and CFI(comparative fit index) value of the structural model were 3.803, 0.063, and 0.938, respectively, which passed the model validation. Perceived value (0.38) is the most important factor affecting travel intention. Travel characteristics (0.08) have a positive direct impact on travel intention, while perceived risk (-0.22) has a negative direct impact. However, travel preferences have no significant impact on travel intention; Travel preferences have a negative effect on travel willingness, but travel characteristics and perceived value have a masking effect on travel preferences, while perceived risk has a mediating effect on them; The pre tax annual income in the individual information of travelers has a moderating effect on the model. As the travel distance increases, the high-income group is more willing to use low altitude aircraft than the low-income group. At the same time, the high-income group is more sensitive to the perceived risks of low altitude aircraft in terms of technological maturity and accident severity. fsQCA analysis shows that there are three configurations that can form travel intention, among which configuration 3 ( type of travel characteristics&perceived value) has the highest sample coverage, explaining 48.9% of the sample cases. When travelers are necessary to travel during peak hours and have a positive understanding of low altitude travel comfort, privacy, etc., they will develop a low altitude travel tendency. The research findings can provide data support for the promotion and policy formulation of low altitude aircraft.

The operational efficiency of aircraft and maximization of aviation transportation benefits have consistantly been pursued by CAAC. It has been indicated by research that the Established on RNP AR (EoR) approach plays an irreplaceable role in improving efficiency, especially for short-distance parallel runway operations, thus, it has received widespread attention in the industry. The integration of EoR approach with sorting strategies was undertaken, with the aim of minimizing flight delay time serving as the objective function, leading to the establishment of a sorting model based on EoR. The impact of EoR-based independent operation versus correlated operation on flight delay time had been compared and analyzed. Addressing the large solution space and the time-sensitive nature of large-scale flight sequencing calculations, The S-shaped function based adaptive particle swarm optimization (SA-PSO) algorithm was proposed to solve the model. Taking the Kunming Changshui International Airport terminal area as an example for case verification, the RECAT-CN operational standard was adopted for wake turbulence safety separation. The results show that, compared to correlated operations, independent EoR operations result in an approximately 38% reduction in total delays. Additionally, the algorithm proposed in the study, when operated independently under the EoR mode results in a reduction of total delays by approximately 15.3%, compared to the first come first served (FCFS) algorithm.

Considering the complex loading environment of the floating offshore wind turbine(FOWT), especially the fatigue damage risks brought by continuous and periodic wave actions, the fatigue performance of FOWT under wave coupling excitation was studied and a long-term fatigue damage assessment method for FOWT was proposed. Taking the Spar FOWT as an example, a nonlinear model under the wave coupling excitation of 8-DOF (dgree of freedom) was established based on the Lagrange equation, and the accuracy of the model was verified. Subsequently, on the basis of the established nonlinear model, the fatigue performance of the example FOWT was discussed according to the proposed method. The results indicate that the fatigue damage of FOWT is closely related to the wave load characteristics, and different damage performance is exhibited under different working conditions. Due to the randomness of sea conditions, only short-term fatigue estimation of the wind turbine is not enough to accurately understand its fatigue performance, and long-term fatigue analysis is needed. Moreover, the peak of short-term fatigue damage at the root of the wind turbine tower occurs near the tower's natural vibration period, while the peak of long-term fatigue damage occurs within the range of high probability sea state periods in the sea. Therefore, efforts should be made to avoid the natural vibration period of the FOWT coinciding with the peak period to prevent high-level damage accumulation and reduce fatigue damage. The analysis also demonstrates the effectiveness of the proposed Monte Carlo based long-term fatigue calculation method for FOWT, which not only has high accuracy but also less time consumption. The proposed improvement method can reduce output fluctuations, enhance stability, and provide more precise results.

In order to enhance the understanding of the characteristics and potential of geothermal resources in the Dunhuang Basin to support exploration and development initiatives, through the application of geothermal exploration techniques and hydrogeochemical analysis, the methods including hydrogen and oxygen isotope testing, Piper diagram analysis, the K-Mg geothermometer, and thermal storage estimation was used to investigate the chemical properties of geothermal water, the recharge source and age, as well as to calculate the thermal storage temperature and geothermal water circulation depth. Furthermore, the potential of geothermal resources in the basin was comprehensively evaluated. The results indicate that the thermal reservoir is primarily composed of argillaceous sandstone, pebbly fine sandstone, and glutenite located in the lower member of the Neogene Shulehe Formation, with the caprock consisting of Quaternary loose rock as well as mudstone and sandy mudstone in the upper member of the same formation. The primary heat source is heat conduction from the upper mantle and deep crust. The geothermal waters are dominated by Cl·SO₄-Na hydrochemical components, with temperatures ranging between 28.7 ℃ and 38.0 ℃ and total dissolved solids (TDS) values varying from 1 146 mg/L to 3 250 mg/L. Isotopic analysis, including δD, δ¹⁸O,³H, and¹⁴C, reveals that the geothermal water represents a mixture of deep groundwater and modern precipitation. The estimated reservoir temperatures range from 39.49 ℃ to 42.75 ℃, and the calculated circulation depths are between 1 020.65 m and 1 268.34 m. These findings suggest that the geothermal resources in the Dunhuang Basin are derived from deep groundwater circulation, replenished by atmospheric precipitation from the southern mountainous regions. The calculated thermal potential modulus of the geothermal fluid is 1.78 × 10⁹ kJ/(km²·a), indicating significant resource potential for future utilization.

In order to explore the problem of fracturing fluid filtration in the process of open hole fracturing, based on the classical filtration model, combined with the two-dimensional model of hydraulic fracturing, ABAQUS finite element software was used for simulation calculation. It is found that in the initial stage of fracture propagation, the pore pressure increases rapidly and increased linearly, and the filtration loss of fracturing fluid also increase rapidly, which is the initial stage of fracture propagation. With the continuous injection of fracturing fluid, the increasing trend of pore pressure becomes slower, and the filtration loss of fracturing fluid also increases slowly. As the crack width gradually widens, it is the crack propagation stage. In the later stage of fracture propagation, when the fracture length reaches a certain length, the change of pore pressure is gradually stable, and the filtration loss of fracturing fluid is slightly reduced compared with the pressure holding state and the fracture propagation stage. In the whole process, the calculation of filtration loss takes into account the dynamic expansion of cracks, which is of certain significance for the actual engineering filtration situation.

To study the surface deformation law of insufficient mining goaf with thick loose layers after grouting, and evaluate the effectiveness of grouting and filling method in treating strip goaf areas, taking a thick loose layer strip goaf of Daizhuang Coal Mine in Jining as an example, theoretical analysis, numerical calculation, surface deformation observation, and deep rock optical fiber monitoring methods were used to compare and analyze the surface deformation laws of the goaf before and after grouting treatment. The results show these as follows. Under the influence of superposition of strip type insufficient mining in the goaf of thick loose layer, the subsidence of goaf decreases during the active period of surface movement, while the residual deformation increases in the later period, the maximum total subsidence of goaf is 611.8 mm and the residual subsidence is 157.8~288.1 mm by using probability integral method and numerical calculation, the surface residual deformation of goaf has great influence on the proposed high-rise buildings. The cumulative subsidence of the surface in the goaf treated by grouting filling method during observation period after grouting is -5.6~-1.5 mm. The comprehensive analysis of deep distributed optical fiber monitoring and surface leveling observation shows that the subsidence of the overlying rock in the goaf after grouting is less than 1 mm/a, and the analysis shows that the surface deformation after grouting is mainly caused by the settlement of the upper thick loose layer. The adoption of grouting filling method can significantly shorten the movement time of overlying strata in the goaf and effectively reduce the deformation of deep strata in the goaf, calculate and analyze the surface deformation value after grouting tends to be stable, the goaf site is in a stable state, and the grouting treatment effect is good, meeting the needs of high-strength engineering construction. The research results can provide guidance for surface deformation prediction, site stability evaluation and treatment effect detection after grouting in goaf under similar conditions.

In order to reveal the influence of strain rates on the macroscopic failure characteristics and microscopic crack propagation laws of rock, sandstone was taken as the research object, and the uniaxial compression tests and real-time monitoring of acoustic emission information were carried out under different loading rates. The influence of loading rates on the macroscopic mechanical response and microscopic fracture morphology of sandstone specimens, such as strength and deformation characteristics, failure mode and fracture characteristics, was analyzed. Based on the evolution of acoustic emission b value with the loading process, the internal crack propagation laws of sandstone specimens under different loading rates were explored. The research results show that within the loading rate range of 1×10^-5~1×10^-2 s^-1, the uniaxial compressive strength and elastic modulus of sandstone samples were positively correlated with loading rates. For every 10 times increase in loading rate, the uniaxial compressive strength and elastic modulus increased by 2.66 MPa and 0.087 GPa, respectively, while the peak strain decreases by 0.213‰. As the loading rate increased, the failure characteristics showed a trend of gradually transitioning from a single inclined through fracture surface to a cross distribution of multiple fracture surfaces, and the average size of the fragments decreased, indicating an increase in the failure of the sandstone sample. At low loading rates, the microstructure of the fracture surface was mainly characterized by intergranular cracks, while as the loading rate increased, transgranular cracks and intergranular cracks alternated, and the fracture characteristics at the intersection of the cracks were obvious, resulting in large-scale grain peeling. As the loading rate increased, the ratio of stress to peak stress corresponding to the turning point where the acoustic emission b value changes from increasing to decreasing decreased. This indicated that the higher the loading rate, the more likely cracks were to propagate inside the specimen and form more obvious large cracks, leading to more severe damage characteristics and complex crack propagation patterns in the specimen. The research results have important guiding significance for understanding the failure characteristics of engineering surrounding rock under complex stress conditions, as well as predicting the damage deterioration law of the internal structure of surrounding rock based on acoustic emission monitoring information.

In order to explore the deformation and failure mechanisms, as well as degradation characteristics of silt slopes under rainfall conditions, a large-scale slope model test apparatus was designed with silt slopes as the research subject. Multi-sensor internal monitoring and 3D laser scanning technology were applied. During slope instability under a rainfall intensity of 30 mm/h, data on moisture content, pore water pressure, soil pressure, and deformation and failure characteristics at various slope locations were collected. Results indicate that sensors at the slope toe have the fastest response, showing the highest rate of change. Rainwater accumulates at the slope toe, causing horizontal seepage, which leads to rapid increases in moisture content at the toe and lower middle sections of the slope, along with a reduction in soil shear strength. Under rainfall intensity conditions, the deformation and failure of silty slopes initiate at the slope toe, where small-scale collapses first occur. These progressively develop into transverse through-cracks, accompanied by minor-scale failures that extend upslope. Ultimately, these processes lead to overall slope failure. The findings offer theoretical insights to support engineering construction and protection in silty slope regions.