In order to investigate the impact of pore and fracture structure on the nonlinear deformation characteristics of rocks during the entire stress-strain process, considering the differences in deformation between pores and the matrix, porous rocks are deconstructed into two components: hard springs and soft springs. The Two-part Hooke's Model (TPHM) and statistical damage theory are introduced. Based on the TPHM, the complete stress-strain relationship of rocks is established, and the porosity evolution equation for the entire stress-strain process of rocks is derived. This model overcomes the limitation of the traditional Two-part Hooke's Model, which is unable to represent the plastic deformation of rocks after yielding. It not only accurately characterizes the nonlinear deformation during the pore compaction stage, plastic yielding, stress drop after peak, and residual stress characteristics in the rock compression process, but also effectively represents the porosity variation during the entire stress-strain process of rocks. Extensive experimental data validation has demonstrated that the theoretical curves of this constitutive model align well with the experimental results, with correlation coefficients consistently exceeding 0.9.

Urban underground logistics system is a complex technology and engineering system developed by the cross integration of modern logistics, transportation, vehicle and underground engineering. Based on the concept of the underground logistics system-pipeline-vehicle collaborative design, a set of cargo vehicle design methods for urban underground pipeline logistics is established. Vehicle technology research and design include vehicle scheme research, vehicle structure and new energy function design, vehicle autonomous driving technology design. This paper designs a special cargo vehicle for pipeline logistics, which is a pipe with inner diameter of 3 800 mm and van with exterior dimension length of 5 000 mm, width of 1 500 mm and height of 2 200 mm. The vehicle has automatic driving, high power, long-distance automatic transportation of goods and wireless charging function when the vehicle is driving in the pipeline. The vehicle design adopts the design concept of green, low-carbon, energy saving and integrated application of more new technological innovations. The technical research and design of cargo vehicle conducted in this paper provides a design scheme of cargo vehicle test sample vehicle and a new vehicle design method of underground pipeline logistics for the implementation of commercial urban underground logistics project.

Underground Logistics System (ULS), as a subterranean urban infrastructure with public utility attributes, can effectively meet urban emergency demands through highly resilient freight networks. However, the operational mechanisms and performance assessment methods for ULS in complex emergency logistics scenarios remain underdeveloped. This study examines ULS emergency service capacity, focusing on the impacts of the operational environment, network structure, and scheduling. A model measuring efficiency, effectiveness, and fairness is developed. Simulations based on freight demand and surface road damage, using the Xianlin case in Nanjing, compare ULS and surface truck delivery. Results show that: ULS exhibits significant advantages in emergency freight performance, particularly under conditions of surface traffic congestion and narrow emergency response time windows. Furthermore, increasing node logistics redundancy, optimizing end-point delivery modes, and ensuring local freight fairness are identified as key factors in enhancing ULS emergency service capacity. This research advances ULS planning theory and offers new insights for urban emergency management.

Subways, as a primary component of urban public transportation, harbor particulate matter within their microenvironments that pose health risks to commuters. To enhance the health of individuals during their subway commutes, a study was conducted to analyze the spatiotemporal heterogeneity of fine particulate matter (PM_2.5) concentrations in the subway microenvironment. The results show that: The PM_2.5 concentration in underground train carriages on weekdays (113.67 μg/m³) is higher than on non-working days (47.62 μg/m³), and the PM_2.5 concentration in underground train carriages is significantly higher than in above-ground and elevated sections (seven times higher) ; lines constructed earlier have higher PM_2.5 concentrations than newly built lines; the PM_2.5 concentration on platforms exhibit a cyclical trend with the arrival and departure of trains; fully enclosed screen doors are more effective than full-height security doors in controlling the accumulation of particles; the PM_2.5 concentration during off-peak hours (75 μg/m³) is lower than during peak hours (102 μg/m³). Furthermore, the study analyzed the potential impact of off-peak travel strategies on the PM_2.5 exposure levels of commuters, the results suggests that off-peak travel could reduce exposure by 25.58% during a single commute. The results of the study provide data support for the prevention.

In order to enhance the prediction accuracy of surrounding rock deformation, enable real-time monitoring of deformation status, prevent deformation failure, and ensure construction safety, a novel underground cavern surrounding rock deformation temporal prediction method based on GRU neural network is proposed to tackle the low training efficiency, slow convergence, and poor generalization of traditional methods, along with the establishment of a corresponding prediction framework. Utilizing monitoring data of surrounding rock deformation from the underground powerhouse on the right bank of the Baihetan Dam, predictions are made and subsequently compared and analyzed with the forecasting results generated by the Long Short-Term Memory (LSTM) neural network algorithm. The results indicate that the GRU neural network model effectively addresses the prediction challenges associated with underground cavern surrounding rock deformation, offering advantages such as simplified structure, relatively fewer parameters, rapid training and convergence rates, and high prediction accuracy. Compared to the predictions derived from the LSTM neural network algorithm, the GRU model demonstrates a reduction in training duration by over 70%, with a corresponding decrease in prediction error of more than 50%. The relative error for cumulative maximum deformation is less than 0.3%, the probability of absolute error less than 0.9 mm is as high as 95%, and the maximum absolute error is only 2.05 mm.

With the excavation of tunnels, the surrounding rock is disturbed and damaged, resulting in changes in its geotechnical parameters. To obtain dynamic variation laws of geotechnical parameters accurately, an inversion method for mechanical parameters of tunnel surrounding rock based on updated boundaries particle swarm optimization (UBPSO) algorithm is proposed. Due to the large fluctuation of optimization results with the particle swarm algorithm, an updated boundaries particle swarm algorithm is proposed. By updating the upper and lower limits of search boundaries dynamically, performing reversal and mutation operations on individual historical optimal values, and updating inertia weights adaptively, the updated boundaries particle swarm algorithm achieves high-precision and fast optimization. The stability test of the Ackley function indicates that compared to the particle swarm optimization algorithm, the updated boundaries particle swarm algorithm has the following advantages, fast optimization speed, high accuracy of results, small fluctuation of outcomes, and less sensitivity to getting stuck in local optima. Based on the updated boundaries particle swarm optimization algorithm, a reverse analysis model for mechanical parameters of tunnel surrounding rock using MATLAB-PYTHON-ABAQUS and on-site monitoring data is established. Taking the YK76+470 to YK76+502.5 section of the Tongluoshan tunnel as an example, the model was used to analyze the on-site monitoring data of the tunnel arch settlement. It was found that the elastic modulus of the colluvial soil layer decreased from 0.200 GPa to 0.106 GPa, the internal friction angle dropped from 14° to 12.072°, and the cohesion value fell from 22 kPa to 19.373 kPa.

In order to investigate the plastic yielding mode of surrounding rock caused by the excavation of shallow twin tunnels, the displacement and additional surface force joint controlling the Schwarz alternation method and complex function method are adopted to solve the elastic stress function of surrounding rock of shallow twin circular tunnels through iterative cycles as an example. The expression of plastic stress components of surrounding rock is obtained based on Mohr-Coulomb failure criterion. The elastoplastic solution of the radius of the plastic zone is determined preferentially by using the stress continuity condition at the interface of the elastic-plastic zones around the shallow twin circular tunnels. The analytical solution for the distribution range of the plastic zones around the shallow twin circular tunnels is established, according to the interconversion relationship between polar coordinates and right-angle coordinates. The rationality and applicability of the analytical solution are verified by numerical simulation results and field measurement results of engineering application. The influence of the center spacing of the twin tunnels on the plastic zones around shallow twin circular tunnels are also analyzed. The results show that the analytical solution in this study can be used to solve the problem of predicting the distribution range of the plastic zones around shallow twin tunnels in actual engineering, and meets the requirement of 20% engineering accuracy, fits well with the numerical simulation results, and has a high calculation accuracy. The distribution range of the plastic zones around shallow twin circular tunnels are positively correlated with the center spacing s of the twin tunnels. Based on the distribution pattern of the plastic zone around shallow twin circular tunnels under the influence of this factor, when the plastic zone reaches the critical state of penetration, the reasonableness of the calculation results of the distribution range of the plastic zones is preliminarily judged. It provides theoretical guidance for similar tunnel engineering design calculation and deformation control of surrounding rock.

Due to its insufficient cover thickness, the excavation face of shallow-shield tunnels is susceptible to passive instability. Tunnel longitudinal slope lead to sudden changes in cover thickness, making the passive failure mechanism of tunnel faces more complicated. There is an urgent need to explore analytical methods for excavation face stability in shallow-buried longitudinal slope shield tunnels. Based on upper bound analysis, a two-dimensional rotation-translation mechanism is proposed that simultaneously considers tunnel longitudinal slope and local instability at the excavation face. The mechanism is comprised of two rigid translation blocks and one rigid rotation block. The ultimate support pressure and failure mode of passive instability at the excavation face are obtained. Finally, the effects of longitudinal slope δ and partial failure ratio η on ultimate support pressure and failure mode of tunnel faces are analyzed, and the reasonableness of proposed models is verified by combining with engineering cases. The results indicate that: Partial failure range of excavation faces gradually increases with the increase of longitudinal inclination angle δ. As the cover depth ratio C/D increases, partial failure of the excavation face evolves into global failure. The rotation angle θ of the rigid rotating block decreases with the increase of the longitudinal inclination δ, and the longitudinal inclination δ has a significant effect on the rotation angle θ.

In order to explore the optimization of air environment and ventilation design parameters in China's extra-long tunnels, this study first analyzed the statistical data of pollutant emission from motor vehicles in China, combined with literature research, and found that the concentration of NO_x in China's tunnels was relatively high, and gradually became the most concerned pollutants in tunnel ventilation. In this study, a field study was carried out in the Yanglin extra-long tunnel in Yunnan. The results show that the peak NO₂ concentration exceeds the ventilation design limit by 2.1 times during the test period, and the emission factors of CO, NO₂ and PM of gasoline vehicles are 0.79 g/(km·veh), 0.04 g/(km·veh) and 10.0 mg/(km·veh), respectively. diesel vehicles are 2.18 g/(km·veh), 1.27 g/(km·veh) and 149 mg/(km·veh), respectively. Compared with the pollutant emission values of domestic and foreign tunnel ventilation design standards, it is found that the current standard values in China are too large. According to the measured emission factors, the required air volume is calculated, and the result is more than 50% lower than the required air volume in Guidelines for Design of Ventilation of Highway Tunnel, which is similar to the required air volume in Standard for the Design of Road Tunnels, and the control item of the required air volume is NO₂ concentration. The results of this study can provide reference for the calculation of pollutant emission and air demand in tunnel ventilation design in China.

To investigate the impact of changes in end-bearing conditions, resulting from shield tunneling, on the bearing capacity of an upper cement-soil pile composite foundation, this study is conducted based on a specific section of the Zhengzhou Metro Line 5 where shield machines cut through cement-soil piles. According to the principle of similarity, a reduced-scale model test of a single cement-soil pile within a composite foundation was designed for laboratory testing. Based on this, a corresponding finite element analysis model was established. By comparing the results from the reduced-scale model test and numerical simulations, the variation patterns of side resistance and end-bearing resistance of the cement-soil pile composite foundation were analyzed as the pile characteristics changed. Studies indicate after the lower part of the cement-soil pile composite foundation undergoes shield tunneling while maintaining a constant vertical load above, there is primarily a redistribution of stress within individual piles, characterized by a transformation between side resistance and end-bearing resistance to balance the upper load. Simultaneously, the neutral point of the side resistance of the cement-soil pile composite foundation moves downward, and its position relative to the pile length is less than that observed in the case where only the pile length is shortened. The change in the length of the cut pile significantly influences the development of side and end-bearing resistances; the contribution of side resistance decreases with an increase in the cut length, whereas the extent to which end-bearing resistance is mobilized slightly increases as the cut length grows.