In order to explore the durability of microbially induced calcite precipitation(MICP) technology to improve the durability of aeolian sandy soil materials, 0.08% polymer absorbent resin (MICP+A) and 0.37% xanthan gum (MICP+B) were used to improve the traditional MICP materials. The microstructure of different cycles of high and low temperature cycle and ultraviolet irradiation was studied by nuclear magnetic resonance technology, and the durability of mineralized sandy soil materials was investigated. The results show that the porosity of both MICP+A and MICP+B materials increases with the increase of cycling cycles. In 20 cycles of high and low temperature cycling tests and 15 cycles of ultraviolet irradiation tests, the MICP+A material shows good stability, and the porosity increment decreases by about 1.8 times and 1.1 times, respectively, compared with the conventional MICP material. Under high and low temperature cycling and ultraviolet irradiation, the crystal structure of calcium carbonate is altered and the percentage of medium-sized pores in the soil increases, causing the 2nd peak of the T₂ spectra of all three materials to be higher than the pre-test peak. The test shows that the polymer water-absorbing resin can improve the stability performance of the traditional MICP specimens, and this study provides a basic experimental basis for the engineering application of microbial mineralized geotechnical materials in the treatment of desert areas.

The low-load one-time construction method of PVC micro-pipe jacking was applied in China and is in its infancy. The small stiffness of the flexible PVC pipe ring leads to the redistribution of soil pressure and the generation of elastic resistance during the jacking process. The jacking force can not be accurately calculated by the existing specifications. The principle and construction method of the PVC micro-pipe jacking method were used to investigate. At the same time, the influence of vertical deformation of PVC pipe on soil arching effect and the additional frictional resistance caused by horizontal deformation were considered based on Terzaghi soil pressure. The corresponding jacking force calculation formula was derived on this basis. Furthermore, the factors that influence the jacking force of PVC pipes were analyzed through finite element numerical simulation. The results indicate that the pressure around the PVC pipe will increase due to the deformation of the pipe. The maximum error between the predicted lower limit and the measured value of the jacking force calculation model proposed is 15%. The measured value is between the predicted upper limit and the lower limit, which proves its applicability. The parametric analysis indicates that the jacking force increases by 1.6 times as the pipe diameter increases by 100 mm and the jacking force increases by about 3 times when the buried depth of the pipeline increases from 4.5 m to 6 m.

In the condition of engineering surcharge near the existing pipeline, the pipeline produce subsidence deformation and further threaten the normal operation of the existing pipeline. Most of the research in this area stays in the finite element and indoor tests, and few theoretical solutions are used to analyze the stress and deformation response of existing pipelines under adjacent engineering surcharge. Based on this, the pipeline-soil interaction under this working condition was investigated by using theoretical analysis. Firstly, the Boussinesq solution was used to analyze the additional stress at the axis of the existing pipeline. Then, the pipeline was simplified as an infinite beam rest on the Pasternak model to further obtain the total energy of the system during the deformation of the pipeline. Finally, the stress and deformation response of the pipeline can be obtained according to the energy variation theory. By comparing with the existing experimental data, the correctness of the proposed method was verified. Compared with the degradation analysis of the proposed method, the proposed method is closer to the measurements. The parameter study shows that the stress deformation of the pipeline wills decrease nonlinearly with the increase of the buried depth of the pipeline. Increasing the diameter of the pipeline would increase the deformation response of the pipeline, the deformation of the pipeline is not sensitive to the angle between the pipeline and the loading area. Increasing the horizontal distance between the pipeline and the loading area can effectively reduce the stress and deformation response of the pipeline, and the deceleration increases first and then decreases. A series of analysis results can be used to analyze the influence of engineering surcharge on the stress and deformation of existing pipelines in practical engineering.

In order to study the influence of slurry shield tunneling parameters on surface settlement, based on the slurry shield tunneling and monitoring data of the left line of the Hesong-Heshan stacked section of Harbin Metro Line 3 project, based on the BP neural network optimized by genetic algorithm, the different settlement output forms were studied. The tunnel distance label was introduced to optimize the neural network fitting effect, and the parameter sensitivity analysis was carried out according to this network model. Three most sensitive parameters were obtained, and exhaustive tests were carried out to further analyze the specific influence of parameters on surface settlement. The research shows that the surface settlement performance of slurry shield tunneling is not closely related to the tunneling parameters after passing through a certain ring for two days, and the surface settlement analysis can focus on the monitoring value of the day. Before, during and after the shield machine passes through a certain ring, it will have different effects on the surface settlement above the ring. Subsequent research on surface settlement based on neural network can be considered to include this index. Among the parameters of slurry shield tunneling, reducing slurry viscosity and increasing slurry specific gravity can control surface subsidence, and increasing propulsion speed can reduce the impact of construction on surface subsidence.

The construction of the shield tunnel for the high-speed railway will impact the settlement of railway tracks, roadbeds, and other structures, potentially affecting the railway’s operation. In order to study the influence of shield tunnel underneath the high-speed railroad in Guiyang area on the settlement pattern of frame box culvert, roadbed and high-speed railway track and the shield construction parameters suitable for Guiyang area, relying on Guiyang Rail Transit Line 3, the model of soil layer-frame culvert-roadbed-track was established to analyze the settlement law of shield construction in limestone on frame culvert, existing high-speed railroad track and roadbed, and to optimize the parameters of shield construction. The results indicate that the settlement of the frame culvert exhibits a “W” shaped transverse and longitudinal settlement pattern, with a peak settlement value of 1.805 mm during the tunneling process. The shield machine’s crossing causes a sudden change in subgrade settlement, with the peak value reaching 1.753 mm. High-speed rail track settlement shows a single peak with excavation, with a peak value of 1.41 mm. Analysis of eight types of shield tunneling pressure and grouting pressure reveals that grouting pressure has a better control effect on settlement than excavation pressure. Increasing grouting pressure leads to a decrease in the peak value of subgrade surface settlement, with the peak value reaching 1.355 mm at 800 kPa grouting pressure. The maximum deformation rate is 20.7%, with grouting pressure set at 800 kPa and tunneling pressure at 100 kPa for the shield machine.

Rockburst is an extremely destructive geological disaster in deep underground engineering. In order to accurately predict the intensity level of rockburst, a method for rockburst intensity level prediction based on parallel fusion graph Transformer (PFGT) was proposed. Firstly, the similarity structure relationship of rockburst data in Euclidean space was utilized to construct graph-structured data. Besides, another kind of graph-structured data was constructed by utilizing multiple rockburst criteria to constrain the structural distortion of rockburst data in European space. Single-scale features of rockburst data was obtained through parallel training. Secondly, a feature fusion graph Transformer strategy was designed, which obtains multi-scale features of rockburst data by fusing two types of graph-structured data features based on Euclidean space and based on rockburst criteria. The method improves the data representation capability by simultaneously utilizing single-scale features and multi-scale features. During the training process, using Transformer for feature fusion enables the model to more comprehensively capture the optimized features of rockburst data, thus improving model performance. Compared with traditional neural networks and other machine learning algorithms, the prediction accuracy of the PFGT model is 94.87%, which is superior to other algorithms, proving the effectiveness of this algorithm and providing a new method for rockburst level prediction.

Restricted by topographic conditions and surrounding environment, the design spacing of double-hole tunnels in western China is often close. Therefore, the special structural form of multi-arch or small close tunnels is often used in the tunnel design. However, in the western region of China, high-intensity seismic zones are widely distributed, and the middle rock wall between the close tunnels is more susceptible under the strong earthquakes, especially the near-field ground motions, which results in large plastic deformation of local surrounding rock, and the safety operation of the tunnel was affected. Therefore, in order to study the distribution of plastic zone of surrounding rock of small close-distance tunnel under near-fault ground motion, reasonable near-fault ground motions were selected, and 3D finite element numerical models considering different tunnel close-distance and surrounding rock conditions were established. The dynamic response characteristics of small close-distance tunnel and the distribution law of plastic zone of surrounding rock were revealed. Thus, through the grouting reinforcement of the middle rock wall, the seismic effectiveness of the reinforcement measures on the plastic zone was verified. The results show that the acceleration response of the arch foot near the middle rock wall tunnel is more significant under the influence of near-field ground motion. Under transverse seismic excitation, the maximum principal stress value of the left spandrel and the right arch foot of the right line tunnel are more significant, while the minimum principal stress of the side walls and the inverted arch of the tunnel is larger. The plastic zone of surrounding rock of small-close-distance tunnel under strong earthquake is greatly affected by rock mass grade. When the tunnel spacing is 0.50 times of the tunnel span, the development of plastic zone in grade Ⅳ and grade Ⅴ surrounding rock is the most serious, and the phenomenon of plastic zone penetration of surrounding rock at the haunch of tunnel near the middle rock wall appears. Taking the plastic zone of surrounding rock as the discriminant index, the grouting reinforcement of middle rock wall is beneficial to the seismic performance of small close distance tunnel. The research results can provide a reference for the seismic safety of small close-distance tunnels in high-intensity earthquake areas.

Accurately predicting bike-sharing flow is essential for optimizing the supply-demand balance of shared bikes and enhancing urban residents’ travel convenience. To address the issues of low prediction accuracy and insufficient capture of spatiotemporal characteristics in bike-sharing flow prediction, a hybrid convolutional-recurrent neural network (Conv3D-GRU) model was proposed. Using Chicago’s 2022 full-year bike-sharing data, experiments were conducted, and the results were compared with those of the 3D convolutional neural network (3D-CNN) model and the convolutional long short-term memory (ConvLSTM) model. The model performance was evaluated using root mean squared error (RMSE), mean absolute error (MAE), and the coefficient of determination (R²). Experimental results show that compared with the 3D-CNN and ConvLSTM models, Conv3D-GRU is improved by 3.25%, 4.90%, 1.14% and 11.94%, 13.70% and 2.46% on RMSE, MAE and R², respectively. This demonstrates that the Conv3D-GRU model has lower prediction errors and higher prediction accuracy, making it an effective and reliable approach for forecasting bike-sharing inflow and outflow.

In the absence of accurate transit demand information, a demand responsive transit(DRT) route planning method based on taxi trajectory data was proposed to predict the “potential demand” of demand responsive transit and provide a feasible plan for route planning before transit operation. Firstly, taxi trajectory data in the study area was obtained through data mining, representing the “potential demand” for passenger travel in the area, and candidate station were determined using the K-means clustering algorithm. Secondly, a benchmark station network was established using these candidate station, with edge benchmark stations designated as the starting and ending points of routes. Utilizing the K-shortest pathes(KSP) algorithm constrained by route length, benchmark chains were generated. Finally, after determining the sub-chain set of the benchmark chains, demand response stations within each sub-chain were searched based on circumferential critical value constraints. Using this algorithm, alternative routes were generated repeatedly within specific time periods, and an initial optimal route was selected based on comprehensive evaluation indices for each alternative route.

A numerical calculation model for airfoil dynamic stall numerical simulation was established by computational fluid dynamics method, and the influence of plunging motion on airfoil unsteady aerodynamic force was analyzed. The simulation results were compared to the pitching motion wind tunnel experimental data of NACA0012 airfoil, and the results of the model under mild stall and deep stall conditions were in good agreement with the experimental values, which verified the accuracy and feasibility of the numerical calculation model. The plunging motion of NACA23012 airfoil was equivalent to the pitching motion, the lift characteristics of airfoil under the two motion modes are very close, but the moment characteristics are obviously different. With the increase of amplitude of plunging motion and inflow Mach number, the difference of moment characteristics is further expanded. With the increase of amplitude of plunging motion, the damping effect of aerodynamic moment of pitching and plunging motions is obviously enhanced, with the increase of inflow Mach number, the damping effect is reduced, and the moment divergence occurs when the Mach number is 0.85.