Tunnel Construction Process Research Articles

The application of GATEM in tunnel geologic risk survey based on complex terrain

Geologic risk assessment and prediction are vital processes preceding the design and construction of tunnels, offering crucial insights for ensuring the safe and efficient execution of tunnel projects. The geologic challenges posed by water inrush and mud bursts in tunnel engineering are often associated with low-resistance karst fracture zones and karst fissures controlled by structural and stratigraphic trends, providing a robust geophysical foundation for the application of electromagnetic methods. In recent years, the rise of numerous deep, lengthy, and challenging tunnel projects in mountainous regions with intricate terrains has significantly heightened the complexity of tunnel exploration. Traditional geophysical detection methods and geologic survey techniques are constrained by site limitations and complex terrains, falling short in effectively detecting geologic disasters within operational tunnels. The flexibility and convenience of the ground-airborne transient electromagnetic method (GATEM) make it particularly suitable for operations in complex terrain areas. Taking the application of GATEM in the Daji Tunnel in Guangxi, China as an example, a background investigation of the topography and lithology of the tunnel area was conducted. A series of data preprocessing, full-field apparent resistivity definition, terrain correction, depth definition, and terrain offset processes were applied to the GATEM field data to obtain the electrical distribution in the tunnel area. By analyzing the electrical variations on the elevation surface above and below the tunnel, we inferred the potential water inflow paths, and the karst positions above the tunnel were mapped. Also, suggestions are made for the complex situations that may occur during the tunnel construction process. Ultimately, the findings are highly congruent with the actual excavation outcomes of the construction unit, which ensured the safe and efficient construction of the tunnel. Thus, the reliability and superiority of the GATEM in the geologic risk investigation of complex terrain tunnel engineering are validated.

Research on Vault Settlement during Three-Step Tunnel Construction Process Based on Sandstone Rheological Experiment.

Tunnel stability is influenced by the rheological properties of the surrounding rock. This study, based on the Ganshen high-speed railway tunnel project, examines the rheological characteristics of siltstone and sandstone through laboratory tests and theoretical analysis. Rheological curves and parameters are derived, revealing the time-dependent deformation mechanisms of the surrounding rocks. A numerical simulation model is created using these parameters to analyze deformation and stress characteristics based on different rock levels and inverted arch closure distances. Results indicate that sandstone follows the Cvisc model, with the Maxwell elastic modulus increasing under higher loads while the viscous coefficient decreases. The vault displacement is mainly affected by the surrounding rock strength; lower strength leads to greater displacement, which also increases with the closure distance of the inverted arch. These findings are crucial for determining the optimal closure distance of inverted arches in sandstone conditions.

Study of the influence of spatial effects on the ground surface and buildings in a two-lane tunnel boring

There are a series of engineering risks, such as ground subsidence, building tilt and cracking, in the process of shield tunnel driving through buildings, which have many adverse effects on urban residents and engineers. In particular, the differences in the effects of the interaction of two-lane tunnels on the building structure and ground deformation field are less often considered under different spatial effects such as construction sequences and tunnel spacings. As well as the problem of analyzing the building as a whole out of reality. To solve these problems, the spatial effect of the shield tunnel underpassing the shallow foundation building is simulated by Plaxis3D software to study the sensitivity analysis of surface settlement and the internal forces and deformation law of the building above in the process of tunneling underpassing with different depths of burial H and horizontal distance D of the double line tunnel. The engineering impact zoning method can investigate the safety of tunnels and buildings under different spatial effects when tunnels pass through buildings. The splitting of the building into plates and columns can reveal the forces and deformation laws of different structural parts. The results show that during the construction process of the double-line tunnel, the tunnel constructed first has a “blocking effect” on the tunnel constructed later, which affects the distribution of the disturbance area to a certain extent and changes the curve shape of the settlement trough. When the “blocking effect” occurs, the surface settlement and building deformation will be significantly reduced. In the internal forces of the building, the plate structure is mainly subjected to changes in axial forces, while the column structure is mainly affected by shear forces and bending moments. The factor of safety of tunnels decreases as the tunnel spacing decreases and as the building loads above increase.

Experimental Study on Infiltration of Seawater Bentonite Slurry

A bentonite slurry mixed with seawater is prone to sedimentation, which will reduce the quality of the filter cake and lower the stability of the excavation surface in undersea tunnels. It is necessary to study the performance and influencing factors of the bentonite slurry mixed with seawater. This article simulates the process of undersea slurry shield tunnel construction, where the pressurized slurry penetrates into the sand layer and forms a filter cake when the shield stops pressurizing. We investigated the effects of bentonite, additives (CMC), fine sand, pressure, and formation permeability on the performance of the seawater slurry and filter cake. The sedimentation of mud caused by seawater interfered with the experiment, which manifested as the increase in bentonite, and delayed the formation of the filter cake. Fine sand with a particle size close to the average value of the formation can improve the speed and quality of filter cake formation. By conducting a sensitivity analysis on experimental data, the degree of influence of various factors on the formation rate, thickness, and porosity of the filter cake was determined. Fine sand and bentonite are the factors that have the greatest impact on the formation rate, thickness, and porosity of the filter cake.

Impact analysis of dust evolution pattern and determination of key ventilation parameters in highland highway construction tunnels

In order to study the influence of ventilation parameters on the ventilation of plateau highway construction tunnels, a highway tunnel construction section in Yunnan is taken as the research background, and Fluent software is used for simulation. The results of the study show that: under the conditions of press-in ventilation, the wind speed in the center of the vortex area in the wind flow field is smaller than the wind speed in the surrounding area, and with the diffusion of the flow field, the average wind speed in the tunnel section gradually decreases, and ultimately stabilizes at the level of 0.5 m/s. After blasting, the dust mass concentration on the return side of the tunnel is higher than that on the duct side. Dust with a particle size of 30 μm or more settled rapidly within 100 m from the boring face, while dust with a particle size of 30 μm or less gradually diffused outward under the action of the wind flow. In the vicinity of the tunnel boring face, reducing the distance from the air outlet to the boring face and increasing the air velocity can improve the dust removal effect. This conclusion can provide theoretical basis and certain guidance for the evolution of dust and dust prevention in the tunnel construction process in plateau area.

Railway track settlement patterns and control measures for multi-tunnel construction underneath a station track group: a case study

This paper is based on the proximity engineering project of the Baishiyi tunnel group passing under the Chongqing West Station track group. Considering the train load and the spatial relationship of the tunnel and track groups, the settlement patterns, horizontal displacement, and differential settlement of the tunnel–strata–tracks system during the excavation process are studied through theoretical calculations and numerical simulation methods. The results indicate that the tunnel vault, strata, and track settlement deformation patterns are similar. Throughout the tunnel construction process, the tracks underwent uplift, settlement, and eventually stabilized. The settlement trough formed by the excavation of the three tunnels below the track group has an impact range of 25–145 m. Between 35 and 75 m, the differential settlement of the double track gradually increases with excavation. As the tunnel face reaches 75 m, the track differential settlement gradually converges and tends to stabilize. To minimize the impact of underpass tunnel construction on track groups, it is recommended to use a combination of full-section hole grouting and surface reinforcement grouting for ground reinforcement. Additionally, optimizing the construction parameters, including the step length and primary support closure time, and strengthening the locking anchor can further reduce the impact.

Theoretical semi-quantitative risk assessment methodology for tunnel design and construction processes

Theoretical semi-quantitative risk assessment methodology for tunnel design and construction processes

Enhancing Urban Tunnelling Efficiency Through Real-Time Geotechnical Parameter Analysis, A Case Study at Kolkata East West Metro Project, KMRCL-1674

The exponential increase in urbanization has heightened the demand for a systematic and rapid mass transportation system in developing countries. One efficient solution has been the construction of underground networks of tunnels using Tunnel Boring Machines (TBMs). Urban tunnels, however, require careful attention to minimizing ground disturbances to avoid adverse impacts on existing infrastructure. The current study focuses on a parametric investigation based on observed trends from the Kolkata East West Metro UG1 project. It undertakes numerical regression to establish correlations, aiming to investigate geotechnical parameters derived from observed operational parameters during tunnel advancement. This correlation allows for the determination and validation of considered geotechnical parameters in real-time, thereby facilitating the optimization of operational parameters. By establishing correlations, the study examines and validates the effect of geotechnical parameters on observed settlement. In conclusion, the consideration of tunnel operational parameters and subsequent establishment of geotechnical parameters can potentially automate the functioning of mechanized tunnelling, leading to more efficient and effective tunnel construction processes.

A dynamic modeling approach to predict water inflow during tunnel excavation in relatively uniform rock masses

Karst landforms are widely distributed all over the world. With the continuous improvement of infrastructure construction, tunnelling in mountainous karst areas is inevitable. Due to the complex hydrogeological conditions in karst areas, groundwater inflow during tunnelling is usually difficult to predict and can cause huge economic losses and casualties. Therefore, finding better ways to improve the prediction of tunnel water inflow is of great significance to ensure the safety of tunnelling. In this study, three commonly used modules (CHD, DRAIN and CFPM1) in MODFLOW are selected and compared to predict the water inflow of tunnels. We find that the CFPM1 module performs better in terms of considering both tunnel size and actual water inflow dynamics during tunnel excavation, which is a continuous process rather than an instantaneous process. Secondly, we build a hypothetical case and predict the tunnel water inflows using above three different modules. We find that the CHD module yields the largest initial and stable water inflow, followed by the DRAIN module, and the CFPM1 yields the least. Besides, as the most sensitive factor in the CFPM1 module, the influence of tunnel diameter on water inflow is discussed. Finally, taking the Shizishan Tunnel as an actual field example, we compare the simulation results of different modules with the measured tunnel inflow. In general, the prediction of the CFPM1 module is the closest to the measured value, and the prediction accuracy is the highest during the conventional tunnel construction process. However, when water-saturated karst features such as underground rivers, caves or faults are exposed during tunnelling, the water level may change instantaneously, which is more consistent with the principle of CHD module. In summary, this study provides theoretical and numerical support for the safe construction of relatively uniform rock mass tunnels in karst areas.

Carbon Footprint Evaluation in Tunnels Excavated in Rock Using Tunnel Boring Machine (TBM)

The generation of CO2 is an important element in assessing the environmental impact generated in a tunnel construction project, making this knowledge very useful for evaluating different alternatives. In this study, an analysis of the carbon footprint has been carried out, including the main elements during the construction phase of a tunnel employing a tunnel boring machine (TBM). The research proposes several options for an easy and quick calculation of CO2 generation in a design phase. Its determination can be crucial for decision-making before and during the execution of any tunnel in the near future. The estimation models have been validated based on real case studies, defining the carbon footprint of each construction element. The proposed procedure can apply to any tunnel. However, it should be noted that it is an approximate analysis, and the limitations described in each section should be considered. The main CO2 generator found in the construction process is the lining element; the percentage varies between 50% in tunnels with smaller diameters (4–5 m) and 75% for tunnels with larger diameters (9–10 m), followed by the auxiliary elements, 16%, and the operation of the tunnel boring machine itself, 11.2%, while the other parts remain in a range between 1.3 and 5.7%. This knowledge makes it possible to define the aspects on which efforts should be focussed to reduce the carbon footprint of the tunnel construction process.

Exact analytical solution for deep tunnels in viscoelastic–plastic rock considering the actual loading path

The rock rheology and time process of tunnel construction make the mechanical responses of rock a function of time and are closely related to the loading path, however, these factors are not properly or correctly considered in analytical studies. The analytical study for deep tunnels in rheological rock is performed in this study, strictly taking into account the viscoelastic‒plastic characteristic of surrounding rocks and the actual loading path during excavation and supporting stages.The plane-strain problem of a circular tunnel in infinite plane under hydraulic far-field stress is simplified, with the time-dependent supporting pressure exerted at a specific time to consider the effect of delay installation of yielding support. The solving procedure as well as the time-dependent analytical solution of displacement, stress, and plastic radius in the excavation and supporting stages are presented in detail when the rocks satisfy the Unified strength theory and perfect plasticity. The analytical solutions agree very well with the numerical results, where the time procedure of tunnel excavation and support is simulated in the numerical model. Furthermore, the proposed solution can predict well the long-term deformation of the Shangxinzhai tunnel, which validates its applicability in real engineering. It is found that the tunnel deformation is underestimated if the unloading stage is not correctly considered. Based on the analytical solution, the influence of the supporting time, start time of the yielding stage and viscosity coefficient on the time dependence of tunnel convergence and stresses is investigated.

Use of GIS and BIM for the integration of tunnel design and construction process in conventional tunneling

This paper presents the development of a framework for the parametric design of tunnels using geographic information system (GIS) mapping and building information modelling (BIM). According to the framework, a parametric representation of each system component (e.g., layers of rock mass, size of excavation, topography, fault geometry, primary lining, secondary lining, rock bolts, etc.) can be incorporated in the GIS model with high levels of detail and used for the automatic generation of numerical models for the design of tunnel construction. This parametric evaluation allows the designer to consider several levels of detail for each component, for the efficient design and process optimization in conventional tunneling. Information between parametric analysis and numerical simulations can be freely exchanged with significantly reduced computational effort while results can be exported into BIM. It is anticipated that the proposed framework could lead to a comprehensive, yet efficient analysis of complex conventional tunneling project using parametric evaluations at the early design stages.

Analysis of Excavation Method on Inlet Tunnel of Controller Construction of Rukoh Dam Pidie District – Aceh Province

The tunnel of controller construction is located in Panton Bunot Village, Tiro Sub District, Pidie District, Aceh Province. The tunnel construction aims to flow the water from Kr. Tiro River to Rukoh inundation for water supply to Rukoh Dam in Keumala Sub District, Pidie District. The research aimed to comprehend engineering geological condition in the study area and determine excavation method at the inlet and proper tunnel support system. The determination of proper excavation method becomes crucial and it is required in maintaining affectivity and efficiency during tunnel construction process. Than excavation method determination is carried out calculation by using empirical method based on output parameter of laboratory test to the rock samples from core drilling in the tunnel track. The outputs are rock conditions as rock mass quality (RQD), discontinuity area density of the rock and rock stress strength. The condition of tunnel track was dominated by silt stone having very poor quality. UCS value was 3 Mpa – 10 Mpa. Joins spacing was less that 60 mm. Empirical analysis of excavation method explained that tunnel opening of Rukoh Controller Construction was highly weathered (HW) and required ripping as excavation type.

Modeling of the accurate application of the Kernel Efficiency Method in the proportioning process of shield tunnel construction

Abstract The existing control strategies for subway construction struggle to address the challenges posed by the impact of large-diameter shield-driven underpass subway tunnels on soil settlement. In this paper, based on the mechanism of ground settlement of the shield tunnel under the KNX method, the influence of the underpass tunnel on the existing tunnel and its surrounding soil stress-strain characteristics is calculated by the Peck superposition method. The KNX method is optimized by optimizing the ratio of KNX slurry and the grouting pressure to control the existing tunnel and the ground settlement. The geotechnical general finite element analysis software is being introduced to conduct numerical simulation and engineering application experiments to verify its effectiveness. The results show that when the bonding force of the grouting material is 350Pa-s, the maximum value of the variation is 3.91mm, and the mobility is more suitable, which can effectively fill the void of the shield machine and reduce the settlement of the foundation. When the grouting pressure is 280kN/m2, the maximum contraction of the tunnel is 6.25mm, which can ensure the safety of the existing tunnel on the basis of the tunnel so that the actual settlement of the soil in the tunnel is minimized. Comprehensively, the optimization of the ratio of the KNP method in the control of the deformation characteristics of the soil and structures under the shield tunnel has effectiveness and can effectively provide theoretical and technical guidance for the construction of subway tunnels under the large-diameter shield under the subway.

Vote-Based Feature Selection Method for Stratigraphic Recognition in Tunnelling Process of Shield Machine

Shield machines are currently the main tool for underground tunnel construction. Due to the complexity and variability of the underground construction environment, it is necessary to accurately identify the ground in real-time during the tunnel construction process to match and adjust the tunnel parameters according to the geological conditions to ensure construction safety. Compared with the traditional method of stratum identification based on staged drilling sampling, the real-time stratum identification method based on construction data has the advantages of low cost and high precision. Due to the huge amount of sensor data of the ultra-large diameter mud-water balance shield machine, in order to balance the identification time and recognition accuracy of the formation, it is necessary to screen the multivariate data features collected by hundreds of sensors. In response to this problem, this paper proposes a voting-based feature extraction method (VFS), which integrates multiple feature extraction algorithms FSM, and the frequency of each feature in all feature extraction algorithms is the basis for voting. At the same time, in order to verify the wide applicability of the method, several commonly used classification models are used to train and test the obtained effective feature data, and the model accuracy and recognition time are used as evaluation indicators, and the classification with the best combination with VFS is obtained. The experimental results of shield machine data of 6 different geological structures show that the average accuracy of 13 features obtained by VFS combined with different classification algorithms is 91%; among them, the random forest model takes less time and has the highest recognition accuracy, reaching 93%, showing best compatibility with VFS. Therefore, the VFS algorithm proposed in this paper has high reliability and wide applicability for stratum identification in the process of tunnel construction, and can be matched with a variety of classifier algorithms. By combining 13 features selected from shield machine data features with random forest, the identification of the construction stratum environment of shield tunnels can be well realized, and further theoretical guidance for underground engineering construction can be provided.

Evaluation of segmental lining response during shield tunnel construction based on field measurements and 3D FEM simulation

Lining safety can be threatened more severely at the construction stage than at the service stage, because the loads at the construction stage are larger. This study presents an in-situ experiment for measuring the loads acting on the lining and the internal forces of the lining to investigate the lining response during both the construction and service stages. A three-dimensional (3D) finite element method (FEM) model that could simulate the main relevant components of the shield tunnel construction process was employed to gain further insight into the mechanisms of the lining response. The influences of the key segment position and assembly sequence on the lining behavior were examined through a comprehensive parametric analysis. The results showed that during the assembly stage, the insertion of a key segment resulted in the most significant increase in the axial force, followed by the assembly of an adjacent segment. The lining responses were significantly influenced by the key segment, particularly during the construction stage, whereas the assembly sequence had a limited effect on the lining responses. During the construction stage, the closer the key segment to the tunnel invert, the greater was the axial force and the smaller was the bending moment of the lining. During the construction stage, the closer the key segment to the tunnel invert, the smaller was the axial force of the tunnel lining and the greater was the bending moment. The circumferential compressive stress reached its maximum value at the joint interfaces. Finally, the jack thrust force was the greatest at the tunnel invert. The key segment should not be placed at this location.

Dynamic parametric modeling of shield tunnel: A WebGL-based framework for assisting shield segment assembly point selection

Recently, there has been widespread attention focusing on the informatization and digitalization of shield tunnel projects. The parametric model of shield tunnels has emerged as a valuable tool for managing engineering information in this context. Several studies have proposed parametric modeling approaches to automate the typesetting of shield lining segments prior to construction. However, the assembly of shield lining segments is a dynamic process that requires the optimization of assembly points based on multiple construction data factors. Existing parametric modeling methods for shield tunnels do not adequately consider the influence of construction factors, limiting their applicability in tunnel construction process. To address these limitations, this study presents a novel framework called the Dynamic Shield Segments Assembly (DSSA) framework, which first develops a new shield segment assembly algorithm using WebGL technology, and then provides a multi-objective optimization method for selecting the shield lining segment assembly points by comprehensively considering construction data. This study also proposes a parametric tunnel segment library, which realizes the information management and space constraints of shield lining segments. Through case studies, it is demonstrated that the proposed framework achieves a modeling efficiency that is more than 35 % higher than that of previous studies.

Propagation characteristics and control technology of blasting vibration in neighborhood tunnel

During the tunnel construction process using the drilling and blasting method, the induced blasting vibration always poses a great threat to the stability and safety of the adjacent tunnel supporting structure. To improve the efficiency and safety of tunnel blasting construction, the vibration propagation and peak particle velocity (PPV) distribution of the lining of an excavated tunnel were investigated during the blasting of an adjacent tunnel located in Guangxi province. The evolution process and distribution characteristics of the PPV of the lining of adjacent tunnels were monitored and analyzed. The results show that the maximum blasting vibration velocity of the lining of the adjacent tunnel can be shown as: PPVx > PPVz > PPVy; hence, the PPVx plays a significant role in the vibration of the adjacent tunnel. According to the tensile stress failure criterion, the PPV threshold was determined to be 12.7 cm/s in this study. To control the damage of surrounding rock induced by the blasting vibration, compound wedge-shaped cutting technology, stress wave dislocation superposition technology, and pre-splitting blasting technology were employed to reduce the impact of blasting vibration on the excavated tunnel.

3-D NUMERICAL MODEL OF SUBSURFACE SETTLEMENT ABOVE TUNNEL LINING

The construction process of a bored tunnel is a complicated process. During tunnelling, loads were acting on the tunnel, hence to support the excavation process, the tunnel lining was installed. Soil stress was redistributed, the surface and subsurface soil settlement behaviour were hard to predict prior to the tunnel advance. In previous, various method was used to investigate the main parameters that effect the subsurface settlements which later can help to predict the surface settlements. In this paper, a numerical modelling was carried out to analyse the subsurface behaviour for certain soil parameters in exist of tunnel segments, grouting layer and shield layer. The subsurface measurements were conducted above the tunnel crown by 2, 4, and 6 m and it is found that the pattern of sub-surface settlement varied based on the soil properties, respectively to the surface settlement.

The Safety Risk Assessment of Mine Metro Tunnel Construction Based on Fuzzy Bayesian Network

With the acceleration of urbanization, the construction of urban subway tunnel networks is advancing towards deeper, denser, and larger subterranean forms. Currently, there is a lack of systematic identification and dynamic reasoning analysis of factors throughout the entire process of subway tunnel construction using the mining method. To reduce the probability of accidents and improve safety risk management in the whole process of subway tunnel construction using the mining method, we propose a dynamic safety evaluation method based on Fuzzy Set Theory (FST) and Bayesian Network (BN). Firstly, based on the identification of main stages of the construction process using the Work Breakdown Structure, a safety risk evaluation index system for subway tunnel construction using the mining method was constructed according to the Risk Breakdown Structure. Secondly, by combining Fuzzy Set Theory, the Analytic Hierarchy Process, and the Bayesian Network, we established a dynamic safety risk evaluation model for subway tunnel construction using the mining method, based on FBN. Lastly, taking a large-section tunnel project using the mining method as an example, the effectiveness and accuracy of this model were verified. The results showed: (1) Causal reasoning analysis indicated that, under the condition of known prior probability, if the case reasoning result is greater than 5%, there is a significant possibility of a safety risk incident. The evaluation results of the model are basically consistent with the actual situation. (2) Diagnostic reasoning analysis revealed that factors such as the tunnel excavation method, the quality of the main waterproof construction, the quality of the detailed construction waterproofing, the design of the monitoring and measurement plan, and the results of the monitoring and measurements, are the main influences on the safety of subway tunnel construction using the mining method. (3) Secondary diagnostic reasoning demonstrated that repeated diagnostic reasoning for the main influencing factors, leading to an investigation path dominated by critical risk factors, can effectively reduce the overall project risk. This research is expected to provide useful insights for the scientific management of safety risks in the construction of subway tunnels using the mining method.