Search Results (94)

This paper presents results of numerical modeling of tunneling using mechanized tunnel boring machines (TBMs) based on a methodology for determining the volume loss cohesionless (loose) soils, denoted as V_L,LSR, for shallow tunnels in dispersive soils to estimate surface and foundation on settlement natural ground. Existing methods for estimating ground surface and structural settlements have significant drawbacks, caused by several factors, including the complexity of determining volume loss using the proposed methodologies, a limited number of empirical parameters describing the technological features of TBM operations, the absence of methods in Russian regulatory documentation for determining volume loss in tunnels with diameters of 6 m or more, among other issues. The study aims to validate a previously developed method for estimating V_L,LSR and an empirical equation for predicting surface settlements, S_max, to assess additional settlements induced by tunneling. The proposed volume loss methodology and the modified S_max expression from Peck R.B. (1969), derived from monitoring data, are used in empirical calculations and numerical modeling of surface and building settlements during TBM tunneling. Validation results include back-analysis of geotechnical “tunnel–ground–structure” interaction models, comparisons of additional settlements from design calculations and field monitoring data, as well as comparisons with existing empirical relationships and relevant regulatory documents, followed by recommendations for their integrated application. The validated methods demonstrate good agreement with observed monitoring data, while providing sufficient engineering safety margins, confirming the applicability of the V_L,LSR and the modified S_max expression by Peck R.B. (1969) for predicting settlements of tunneling and identifying directions for further research. Full article

Farmland shelterbelts are vital ecological infrastructure for sustaining agriculture in arid regions, where high winds, soil erosion, and water scarcity severely constrain productivity. While their protective functions—reducing wind speed, controlling erosion, moderating microclimates, and enhancing yields—are well documented, previous studies have largely examined individual structural elements in isolation, leaving their interactive effects and trade-offs poorly understood. This review synthesizes current research on the structural optimization of shelterbelts, emphasizing the critical relationship between their physical and biological attributes and their protective functions. Key structural parameters—such as optical porosity, height, width, orientation, and species composition—are examined for their individual and interactive impacts on shelterbelt performance. Empirical and modeling studies indicate that moderate porosity maximizes wind reduction efficiency and extends the leeward protection zone, while multi-row, multi-species configurations effectively suppress soil erosion and improve microclimate conditions. Sheltered areas experience reduced evapotranspiration, increased humidity, and moderated temperatures, collectively enhancing crop water use efficiency and yielding significant improvements in crop production. Advanced methodologies, including field monitoring, wind tunnel testing, computational fluid dynamics, and remote sensing, are employed to quantify benefits and refine designs. A multi-objective optimization framework is essential to balance competing goals: maximizing wind reduction, minimizing water consumption, enhancing biodiversity, and ensuring economic viability. Future challenges involve adapting designs to climate change, integrating water-efficient and native species, leveraging artificial intelligence for predictive modeling, and addressing socio-economic barriers to implementation. Building on this evidence, we propose a multi-objective optimization framework to balance competing goals: maximizing wind protection, minimizing water use, enhancing biodiversity, and ensuring economic viability. We identify key research gaps including unresolved porosity thresholds, the climate resilience of alternative species compositions, and the limited application of optimization algorithms and outline future priorities such as region-specific design guidelines, AI-driven predictive models, and policy incentives. This review offers a novel, trade-off–aware synthesis to guide next-generation shelterbelt design in arid agriculture. Full article

The construction of urban underground space develops very fast, and tunnel intersection construction has become a common practice, attracting significant attention due to the associated deformation responses and risk control challenges. To systematically review the research landscape and cutting-edge developments in this field, this study conducts a comprehensive analysis based on 744 publications (1994–2025) from the Web of Science Core Collection using bibliometric methods. Firstly, through visual analyses of annual publication trends, journal distributions, and keyword co-occurrences, the study reveals the evolution and research hotspots of the past three decades. Subsequently, three core dimensions are explored in depth: deformation mechanisms and patterns, deformation analysis methods for ground and existing structures, and ground control and reinforcement techniques. The review highlights the following: (1) Research focus has shifted from single construction scenarios to the complex interactions among multiple tunnels, yet the cumulative deformation effects caused by repeated soil disturbances during sequential excavation remain inadequately understood. (2) The bidirectional coupling between existing tunnels and surrounding soil has become a major research focus and challenge. Particularly in the presence of high-stiffness structures, the “free-field” assumption in the commonly used two-stage method is being questioned, necessitating the development of more refined computational theories. (3) Optimization of construction schemes under complex conditions is key to disturbance control, but current research still lacks systematic multi-objective optimization approaches. In addition, this paper analyzes the current research status and future directions to enhance the deformation perception capability and control technologies in tunnel construction influence zones, thereby further improving the safety and intelligence level of tunnel construction. Full article

With the increasing demand for urban rail transit capacity, shield tunneling has become the predominant method for constructing underground metro systems in densely populated cities. However, the spatial interaction between shield tunnels and adjacent retaining structures poses significant engineering challenges, potentially leading to excessive ground settlement, structural deformation, and even stability failure. This study systematically investigates the deformation behavior and associated risks of retaining systems during adjacent shield tunnel construction. An orthogonal multi-factor analysis was conducted to evaluate the effects of grouting pressure, grout stiffness, and overlying soil properties on maximum surface settlement. Results show that soil cohesion and grouting pressure are the most influential parameters, jointly accounting for over 72% of the variance in settlement response. Based on the numerical findings, a Bayesian network model was developed to assess construction risk, integrating expert judgment and field monitoring data to quantify the conditional probability of deformation-induced failure. The model identifies key risk sources such as geological variability, groundwater instability, shield steering correction, segmental lining quality, and site construction management. Furthermore, the effectiveness and cost-efficiency of various grouting reinforcement strategies were evaluated. The results show that top grouting increases the reinforcement efficiency to 34.7%, offering the best performance in terms of both settlement control and economic benefit. Sidewall grouting yields an efficiency of approximately 30.2%, while invert grouting shows limited effectiveness, with an efficiency of only 11.6%, making it the least favorable option in terms of both technical and economic considerations. This research provides both practical guidance and theoretical insight for risk-informed shield tunneling design and management in complex urban environments. Full article

In recent years, the increasing complexity of shield tunneling environments has made it critical to control the deformation of adjacent excavation structures and surrounding soils. This study employs numerical simulation using MIDAS GTS/NX to comprehensively analyze the spatial interaction factors between shield tunnels and wall-pile-anchor-supported foundation pits. Structural parameters of the retaining system and tunneling conditions are also evaluated to identify the key factors influencing construction-induced deformation. The results show that the maximum settlement of the adjacent retaining wall occurs when the tunnel burial depth reaches 1.4L, where L is the height of the diaphragm wall. In addition, when the horizontal distance between the tunnel and the excavation is less than 0.75D (D being the tunnel diameter), significant settlement deformation is observed in the nearby support structures. A linear correlation is also identified between the variation in tunnel crown settlement and the excavation depth of the overlying pit during tunnel undercrossing. Furthermore, sensitivity analysis indicates that increasing the embedment depth of the diaphragm wall effectively reduces horizontal displacement at the wall base. Increasing the wall thickness decreases displacement in the upper section of the wall. Similarly, increasing pile diameter and anchor length and diameter, while reducing the inclination angle of anchors, are all effective in minimizing the lateral displacement of the support structure. Full article

Accidental surface surcharge will generate additional load in the stratum, which then leads to unfavorable impacts on the underlying shield tunnel. This paper proposes a probabilistic analysis method to address this problem. In this framework, an improved soil–tunnel interaction model considering the nonlinearity of the subgrade is established at first, and the Newton–Raphson iterative solution algorithm is employed to acquire tunnel responses. Then, the random field models of the initial stiffness and the ultimate reaction of the subgrade are constructed to realize the spatial variability of soil properties. Finally, with the aid of the Monte Carlo Simulation method, the probabilistic analyses on tunnel responses are performed by combining the improved soil–tunnel interaction model and the random field model of subgrade parameters. The applicability and the superiority of the improved soil–tunnel interaction model are validated by a historical case from Shanghai Metro Line 9. The results prove that the traditional linear foundation model will overestimate the bearing capacity of the subgrade, thereby leading to overly optimistic assessments of surcharge-induced tunnel responses. This shortcoming could be addressed by the improved nonlinear soil–tunnel interaction model. The influences of spatial variability of soil properties on tunnel responses are nonnegligible. The stronger the uncertainties of subgrade parameters, in terms of the initial stiffness and the ultimate reaction concerned in this work, the higher the failure risk of the shield tunnel subjected to the surcharge. The failure modes of the tunnel subjected to the surcharge are controlled by the longitudinal curvature radius of the tunnel within the current assessment criteria, which means if this evaluation indicator can be restricted within the allowable value, then the opening of the circumferential joint and the longitudinal settlement can also meet the requirements. Compared with the influences of the uncertainty of the subgrade ultimate reaction, the spatial variability of the subgrade initial stiffness has greater influences on tunnel failure risk under the same conditions. An increase in the range of surcharge will raise the risk of tunnel failure, while the influence of tunnel burial depth is just the opposite. Full article

The behavior response of an existing shield tunnel to under-cross tunneling is fundamentally governed by the tunnel–soil interaction. In this study, the existing tunnel is simplified as a single-variable Timoshenko beam to address the shear locking issue of the conventional Timoshenko beam. An elastic continuum solution, which can be degenerated into the Winkler–Timoshenko model, is established by considering the tunnel–soil interaction to evaluate the existing tunnel’s response to underlying tunneling. Meanwhile, greenfield settlement is described using a modified Gaussian function to fit practical engineering cases. The joint opening and segmental dislocation are also quantified. The applicability of the proposed method is validated by two reported engineering cases, where measured greenfield settlements are used to verify the modified Peck formula. Key parameters, including the ground loss rate, intersection angle, tunnel–soil stiffness factor, and vertical clearance, are discussed. The results show that the proposed method can provide references for predicting the potential diseases of existing tunnels affected by new tunnel excavation. Full article

The existence of fault zones in high-intensity earthquake areas has a serious impact on engineering structures, and the longitudinal response of tunnels crossing faults needs further in-depth research. To analyze the tangential contact effect between the surrounding rock and the tunnel lining, and the axial deformation characteristics of the tunnel structure, tangential foundation springs were introduced and a theoretical model for the longitudinal response of the tunnel under fault dislocation was established. Firstly, the tunnel was simplified as a finite-length beam. The normal and tangential springs were taken to represent the interaction between the soil and the lining. The fault’s free-field displacement was applied at the end of the normal foundation spring to simulate fault dislocation, and the differential equation for the longitudinal response of the tunnel structure was obtained. The analytical solution of the structural response was obtained using the Green’s function method. Then, the three-dimensional finite difference method was used to verify the effectiveness of the analytical model in this paper. The results show that the tangential contact effect between the surrounding rock and the lining has a significant impact on the longitudinal response of the tunnel structure. Ignoring this effect leads to an error of up to 35.33% in the peak value of the structural bending moment. Finally, the influences of the width of the fault zone, the soil stiffness of the fault zone, and the stiffness of the tunnel lining on the longitudinal response of the tunnel were explored. As the fault width increases, the internal force of the tunnel structure decreases. Increasing the lining concrete grade leads to an increase in the internal force of the structure. The increase in the elastic modulus of the surrounding rock in the fault area reduces the bending moment and shear force of the structure and increases the axial force. The research results can provide a theoretical basis for the anti-dislocation design of tunnels crossing faults. Full article

Yellow shoulder disorder (YSD) is characterized by discolored regions beneath the fruit’s epidermis, impacting the ripening process and rendering tomatoes unsuitable for marketing. YSD poses a significant challenge in high-tunnel (HT) tomato production, a system that has gained prominence for its ability to extend growing seasons and enhance crop quality. This review delves into the various factors influencing YSD occurrence, including soil nutritional status, weather, plant variety, and the interactions between these factors, contributing to the occurrence of YSD in HT microclimate. The severity of YSD symptoms, ranging from minor to significant discoloration, highlights the complexity of this disorder. This review highlights research gaps on the effects of temperature, relative humidity, nutrient imbalance, soil water management, clay minerals, and how their interactions influence YSD in HT microclimates, emphasizing the need for comprehensive studies to understand the complex relationships between soil health, nutrient management, and tomato quality in HT microclimates and the need for further research to sustain high-quality tomato production in HTs. Full article

With the rapid development of urban rail transit, the impact of shield tunneling on existing pipelines is increasing. To protect pipeline safety, this research focuses on the complex pipelines in the Shaluo shield tunneling section, utilizing FLAC3D numerical simulation software to investigate the deformation characteristics of cast iron pipelines during shield construction. Additionally, it quantifies the influence of pipeline materials on deformation and establishes the pipeline safety risk grading system. Safety assessment of pipelines based on the research. The research indicates that (1) The deformation difference between the tops of the pressure and pressureless pipeline is less than 1 mm, suggesting that pipeline deformation is minimally influenced by pressure. The deformation is the largest at the entrance and gradually decreases along the direction of excavation, indicating that the deformation has an obvious hysteresis effect. (2) The threefold variation in maximum deformation among pipelines of different materials during shield tunneling indicates the high sensitivity of pipeline material properties to shield construction processes. (3) By analyzing and discussing the literature and local norms, the deformation value of the pipeline is taken as the evaluation index. And the pipeline assessment system is established. (4) Cast iron pipelines at the start of the shield have the highest safety, and concrete pipelines at the beginning of the shield are the lowest. Full article

The seismic design of underground or aboveground structures is commonly based on the free-field assumption, which neglects the interaction between underground structures–soil–aboveground structures (USSI). This simplification may lead to unsafe or overly conservative, cost-intensive designs. To address this limitation, a series of shaking table tests were conducted on a coupled USSI system, in which the underground component consisted of a subway station connected to tunnels through structural joints to investigate the “city effect” on-site seismic response, particularly under long-period horizontal seismic excitations. Five test configurations were developed, including combinations of one or two aboveground structures, with or without a subway station. These were compared to a free-field case to evaluate differences in dynamic characteristics, acceleration amplification factors (AMFs), frequency content, and response spectra. The results confirm that boundary effects were negligible in the experimental setup. Notably, long-period seismic inputs had a detrimental impact on the field response when structures were present, with the interaction effects significantly altering surface motion characteristics. The findings demonstrate that the presence of a subway station and/or aboveground structure alters the seismic response of the soil domain, with clear dependence on the input motion characteristics and relative structural positioning. Specifically, structural systems lead to de-amplification under high-frequency excitations, while under long-period inputs, they suppress short-period responses and amplify long-period components. These insights emphasize the need to account for USSI effects in seismic design and retrofitting strategies, particularly in urban environments, to achieve safer and more cost-effective solutions. Full article

Due to the complexity of planning and constructing underground lines, construction challenges—such as close proximity and multi-line interactions—are increasingly being recognized, along with their associated safety hazards. The visual observation of tunnel deformation and changes in the surrounding strata is difficult. In this study, laboratory model experiments were conducted using a mixture of liquid paraffin, n-tridecane, and silica gel powder, combined in specific proportions to create a transparent material that simulates natural soft rock. The new tunnel was designed to simultaneously cross over and under two existing tunnels. The impact of the new tunnel on the existing tunnels was examined, with excavation length and soil layer thickness considered as the primary influencing factors. The results indicate that excavating the new tunnel causes settlement deformation in the tunnels above and heave deformation in the tunnels below. The magnitude of deformation increases as excavation progresses but decreases with the greater thickness of the soil interlayer. For an existing tunnel, variations in the thickness of the soil interlayer not only affect its own deformation but also disturb the tunnel on the opposite side. Therefore, to ensure safer and orderly urban tunnel construction and to address the “black box” effect, it is essential to study the deformation characteristics of existing tunnels and their surrounding rock during the construction of new tunnels. Full article

In long-distance, large-section rectangular pipe jacking operations, machine deviation is an inevitable factor that poses substantial challenges to the accurate prediction of frictional resistance. To address this issue, a novel methodology is proposed to analyze the dynamic interactions at the pipe–soil–slurry interfaces. This approach integrates real-time alignment monitoring with the Winkler elastic foundation theory to enhance predictive accuracy. A comprehensive predictive framework is developed for excavation profiles and pipeline deflection curves under varying thrust distances, enabling the quantification of complex contact states. By applying Newton’s law of friction and the Navier–Stokes fluid mechanics equations, calculation methods for the frictional resistance of pipe–soil contact and pipe–mud contact are systematically derived. Furthermore, a predictive model for the jacking force in long-distance rectangular pipe jacking, accounting for complex contact conditions, is successfully established. The jacking force monitoring data from the 233.6-m utility tunnel pipe jacking project case is utilized to validate the reliability of the proposed theoretical prediction method. Parametric analyses demonstrate that doubling the subgrade reaction coefficient enhances peak resistance by 80%, while deviation amplitude exerts a 70% greater influence on performance compared to cycle parameters. Slurry viscosity emerges as a critical factor governing pipe–slurry interaction resistance, with each doubling of viscosity causing up to a 56% increase in resistance. The developed methodology proves adaptable across five distinct operational phases—machine advancement, initial jacking, stable jacking, deviation accumulation, and final jacking—establishing a robust theoretical framework for the design and precision control of ultra-long pipe jacking projects. Full article

Wind erosion significantly threatens sustainable development in desert regions, causing severe soil degradation. Investigating the influence of roughness elements on wind–sand interactions is vital for devising effective wind erosion control strategies. This study examined the effects of smooth and porous surface roughness elements on wind–sand activity and the wind erosion rate of a sand bed surface. Wind tunnel experiments were conducted with 10% coverage of these elements on the sand bed surface under varying wind speeds. Results showed that porous-surfaced roughness elements were less responsive to wind speed than smooth-surfaced spherical elements, significantly slowing wind erosion and enhancing sand bed stability. The porous-surfaced elements significantly reduced wind erosion rates by 21.8% at low wind speeds (8 m/s) and 18.23% at high wind speeds (14 m/s), compared to smooth-surfaced elements. The porous-surfaced spherical roughness elements effectively reduced the secondary lifting of sand particles by increasing the specific surface area, thereby improving the bed surface’s wind erosion resistance. These findings provide critical insights for optimizing sand control materials and developing more effective wind erosion mitigation strategies, offering a valuable reference for combating desertification. Full article

Based on FLAC3D finite element analysis and field measurements, this paper studies the synchronous excavation of the deep foundation pit and the adjacent underground channel in the 17th section of the Beijing Metro Line 10 Phase II project. Due to the very tight schedule and deadline, an underground channel has been added between the double-arch tunnel and the deep foundation pit and excavated synchronously with the deep foundation pit. The minimum distance between the two excavations is 5 m. It was found that (1) the underground channel excavation destroys the intact structure of the soil around the channel and foundation pit on a larger scale, which affects the formation of soil arch behind the retaining pile and thus increases the lateral pile displacement, and the addition of anchor cables at the north and south sides of the foundation pit is not necessary; (2) if conditions permit, it is the safest to excavate the underground channel first and then the foundation pit; (3) the primary interaction spacing between the two adjacent excavations is the same depth as that of the foundation pit, and when the spacing increases to twice the depth of the foundation pit, there is basically no interaction; (4) compared with the solid and heavy soil, the adjacent existing underground channel is like a “hollow, elastic, light” tube and more sensitive to the foundation pit excavation, whose uplift and deformation rebound could exert a force on the surrounding soil and then enlarge the lateral displacement of the retaining pile. Full article