Tunnel Construction Method Research Articles

Characteristic analysis of tunnel collapse arch in weak rock mass

The stress of surrounding rock and supporting structure is very complicated during the construction of a loose rock tunnel. The characteristics analysis of collapse arch is very important for the construction safety. This paper compares and analyzes the applicability of the full section method and the three-step method under shallow buried loose surrounding rock, reveals the influence law of tunnel excavation height span ratio on the stability of a pseudo-collapse arch of surrounding rock under shallow buried loose surrounding rock, and rationally chooses the three-step method as the dominant construction method of tunnel construction under this geological condition. For the three-step construction method, the optimization study of the excavation height of the upper step is carried out, the relationship between the excavation height of the tunnel and the stress concentration area under the condition of shallow buried loose surrounding rock is revealed, the influence of surrounding rock stress release on the stability of the tunnel surrounding rock is explored, and the damage of tunnel rock mass caused by the stress concentration phenomenon is analyzed. It is determined that the optimal excavation height of the upper step is 0.4H under the geological conditions of the DS project in Sichuan province, China, under construction. This paper analyzes the influence of structural plane spacing on the stability of a tunnel collapse arch under shallow buried loose conditions and reveals the law that the smaller the structural plane spacing, the worse the self-bearing capacity of the collapse arch, and the higher the risk of engineering accidents such as rock collapse or even collapse in the tunnel, which effectively guides the safe construction of the tunnel under shallow buried loose geological conditions.

OPTIONS SELECTION AND IMPACT STUDY OF INTERCITY RAILWAY TUNNEL CONSTRUCTION UNDER AIRPORT INTERZONE

The selection of tunnel construction program for intercity railroad tunnel under the airport must consider the limitations of environmental conditions and the scale of tunnel construction, and the impact of construction on the airport must be controlled within safe limits. Combined with the intercity rail transit tunnel project through the airport area surrounding environment and engineering geological conditions, the use of theoretical analysis, numerical simulation and other methods, comprehensive navigation, technology, construction period, cost, construction impacts and other aspects of the comparative analysis of the tunnel construction method of open excavation method and shield method, the results show that: (1) Due to the soft soil and groundwater in the tunnel excavation area, the risk of open excavation is greater, while the shield method is more suitable for longer silty soil tunnels without affecting the navigation, accordingly, the shield tunnel construction is more suitable for the tunnel construction under the airport. (2) Open excavation method has the shortest construction period to meet the requirements of rail transit, the unit cost is between 1 and 2 shield machines, and the total cost is close to 2 shield machines; for lower total cost, choose 1 shield machine, for shortening the construction period, choose 2 shield machines. (3) The maximum ground settlement caused by shield tunneling construction is 20mm, the maximum vertical differential settlement perpendicular to the tunnel is 2.8cm, and the maximum differential settlement is 0.93 ‰. On the one hand, it meets the requirements of airport settlement control, and on the other hand, it has little impact on the vertical connecting road and west station apron, and will not affect the opening of the airport runway and the operation of the terminal.

Optimization of Blasting Parameters Considering Both Vibration Reduction and Profile Control: A Case Study in a Mountain Hard Rock Tunnel

The number of excavated tunnels is increasing day by day, and the corresponding engineering scale is also getting increasing. Safe, efficient, and economically beneficial tunnel construction methods are indispensable in the process of crossing mountains and steep ridges in the southwest region. However, behind the improvement of transportation infrastructure in Southwest China is the support provided by the rapid development of blasting industry engineering technology in China. In the process of tunnel construction using the drilling and blasting method, in addition to blasting vibration disasters the phenomenon of overbreak and underbreak caused by blasting construction is a prominent problem. This phenomenon not only affects the safety and stability of the tunnel excavation but also seriously increases the construction cost. Based on a short mountain hard rock tunnel project in southwest China, this paper studies the effect of blasting construction on the blasting vibration of adjacent structures and the influence of tunnel contour forming quality. Through the monitoring and analysis of in situ blasting vibration, the Sadowski formula is used to study the attenuation law of blasting vibration velocity in different tunnel sites, which provides a theoretical basis for tunnel blasting vibration control. This article compares the use of overbreak and underbreak value with the traditional method to determine the degree of overbreak and underbreak. It introduces the analysis of contour section fractal dimension value and uses fractal theory in the Python image processing module to accurately and quantitatively describe the problems of tunnel overbreak and underbreak. The feasibility and accuracy of this method have been verified, by combining the total station and 3D laser scanner results of overbreak and underbreak measurements of the Brenner Base Tunnel and a short hard rock tunnel in a mountainous area of southwestern China. The blasting scheme was optimized from the aspects of cut hole form, detonator interval time, and peripheral hole charge structure, and the rationality of the optimized scheme was verified according to the on-site blasting experiments. It has a profound influence on strengthening the protection of adjacent tunnel structures and improving the economic benefit of mountain highway projects.

Framework for determining the safety distance of karst caves adjacent to tunnels

Karst caves pose safety issues for tunnels in karst areas. Karst caves at a certain distance from the tunnel must be treated fully to mitigate risks. A threshold of 3 m is typically adopted; caves within this threshold are fully treated, while those beyond are left untreated, regardless of the geological environment, cave features, tunnel design, operating conditions, etc. This poses risks to tunnel safety during construction and operation. This paper proposes a novel framework based on the aforementioned aspects to determine the treatment distance for caves from the perspective of uncertainty and risk. Geological conditions include the soil and rock type, weathering degree, underground water system, and pH. Karst caves primarily include the size, shape, distance, spatial distribution, density, and filling condition; the tunnel aspect refers to the tunnel diameter, construction method, design life, importance, lining, and tolerable criterion; and operation conditions refer to the vehicle speed, operation time, vehicle load, and maintenance. Herein, the parameters/indices for these aspects and methods to quantify their values are described. A decision-making process is illustrated to revive the mindset of risks in tunnel engineering. The proposed framework is effective for optimizing decision-making in karst cave treatment for tunnels in karst areas.

Damage and reliability analysis of double-arch tunnel without a middle pilot tunnel under blast load

In this study, a new type of multi-arch tunnel construction method is proposed. This effort is undertaken due to the many disadvantages of the traditional multi-arch tunnel construction method. Furthermore, this method omits the construction of a middle pilot tunnel, and it has the advantages of safety, high efficiency, and being economical. When using the method of continuous arch tunneling without a middle pilot tunnel, the blasting of the first tunnel and the following tunnel has a greater impact on the surrounding rock damage, as well as on the supporting structure of the same cross-section. Therefore, this study uses LS-DYNA finite element software to construct a three-dimensional numerical model. In addition, the perimeter rock damage law and mechanical response characteristics of the supporting structure in the same cross-section of the first tunnel, as well as the following tunnel after blasting without a middle pilot tunnel, are analyzed. At the same time, the results of the study are based on optimizing the blasting program, and these are then applied to the field. Through the results, it is found that, after blasting a continuous arch tunnel without a medial pilot tunnel, the surrounding rock damage in the arch cross-region of the double-arch tunnel (where the arch top and the arch shoulder are more significant) and the effective stress of the supporting structure exceed the strength design value. In addition, the maximum adequate pressure is distributed in the medial diaphragm wall. With the optimized blasting scheme, the range of the peripheral rock damage is reduced by a maximum of 67%, and the effective stress in the supporting structure is reduced by 25.9–64.8%. The research results are of great significance in terms of improving construction safety, economic efficiency, and project quality, as well as in promoting the research and development of new work methods for double-arch tunnels.

Assessment for shallow and large tunnel construction in weak ground conditions: Application of tunnel boring machines

AbstractWith recent technological advancements, tunnel boring machines (TBM) have developed and exhibited high performance in large diameters and weak ground conditions. Tunnels are crucial structures that significantly influence the timelines of highway and railway projects. Therefore, the construction of tunnels with TBMs becomes a preferred option. In this study, a comparative analysis between TBM and the New Austrian Tunneling Method (NATM) for tunnel construction is performed in the construction of the T1 tunnel with a diameter of 13 m, which is the longest tunnel in the Eşme‐Salihli section of Ankara‐İzmir High‐Speed Railway Project (Türkiye). The selection of TBM type, measures taken in problematic sections, and application issues of TBM are discussed. The impact of correct description of geological and geotechnical conditions on both selection and performance of TBM is presented. An earth pressure balanced type TBM is chosen for the construction of the T1 tunnel. Because of the additional engineering measures taken before excavation in problematic areas, the tunnel was completed with great success within the initially planned timeframe. From this point of view, this study is an important case and may contribute to worldwide tunneling literature.

Exploration of Advanced Geological Prediction for the Double-arch Highway Tunnel in Karst Area

Combined with the construction method of a highway double-arch tunnel in the karst area, a comprehensive advanced geological prediction method combining geological radar and advanced horizontal drilling is proposed, and the comprehensive advanced geological pre- diction method is successfully applied to the construction of a highway double-arch tunnel in a karst area of Guangxi. The result of site con- struction proves that the method has a satisfactory forecasting effect.

Stochastic Simulation of Construction Methods for Multi-purpose Utility Tunnels

The traditional method of installing underground utilities (e.g., water, sewer, gas pipes, electrical cables) by burying them under roads has been used for decades. However, the repeated excavations related to this method cause problems, such as traffic congestion and business disruption, which can significantly increase financial and social costs. Multi-purpose Utility Tunnels (MUTs) are a good alternative for buried utilities. Although the initial cost of MUTs is higher than that of the traditional method, social cost savings make them more feasible, especially in dense urban areas. Different factors, such as the specifications of utilities, the location of the MUTs, and the construction method, should be investigated to determine if MUTs can be an economical and practical alternative. The construction method is one of the most important factors to assess to have a successful MUT project and reduce its impact on the surrounding area. Simulation can be used to investigate the different construction methods of MUTs. In this paper, two Stochastic Discrete Event Simulation models depicting two MUT construction methods (i.e., microtunneling and cut-and-cover) are developed to analyze the duration and cost of the MUT projects. Also, 4D simulation models of these methods are developed for constructability assessment of these projects.

Performance of the suspension method in large cross-section shallow-buried tunnels

Large cross-section tunnel construction induces ground surface settlements, potentially endangering both subterranean projects and nearby above-ground structures. A novel tunnel construction method, known as the suspension method, is introduced in this paper to mitigate surface settlement. The suspension method employs vertical tie rods to establish a structural connection between the initial tunnel support system and the surface steel beam, thereby exerting effective control settlements. To analyze the performance of the proposed method, systematic numerical simulations were conducted based on the practical engineering of Harbin Subway Line 3. The surface settlement and vault settlement characteristics during construction are investigated. The results show a gradual increment in both surface and vault settlement throughout the construction process, culminating in a stabilized state upon the completion of construction. In addition, compared to the double-side drift method and the Cross Diaphragm Method (CRD) method, the suspension method can obviously reduce the surface settlement and vault settlement. Moreover, the surface settlements and the axial force of tie rods were continuously monitored during the construction process at the trial tunnel block. These specific monitoring measurements are illustrated in comparison to numerical analysis results. The monitored results show great agreement with the numerical predictions, confirming the success of the project. This research can serve as a valuable practical reference for similar projects, offering insights and guidance for addressing ground surface settlements and enhancing construction safety in the domain of large cross-section tunneling.

Simulation of bench stepping and optimization of bolt parameters based on multiple geological information fusion

In the stability analysis and design of rock support for tunnels, the establishment of a refined numerical model relies on reliable and accurate geometrical information of structural planes. To better analyze and optimize the tunnel construction method and support mode, it is crucial to establish a refined numerical model for the tunnel. Based on the developed geotechnical intelligent analysis and multi-interpretation system, the feature extraction and interpretation of the rock mass structural surface are achieved. Meanwhile, coupled with multiple geological information, the comprehensive analysis and judgment of rock mass structural surface information are achieved through continuous dynamic tracking. According to this method, based on grade IV fractured rock data collected from the construction site of Dapuling tunnel, the safe distance of step in bench excavation method has been optimized based on the numerical modelling, and the corresponding bolt support design. The optimized tunnel excavation process is more stable and safer, providing a scientific basis for predicting, identifying, controlling, and preventing rockfall disasters during the excavation process of tunnels and underground caverns in fractured rock masses.

Back-analysis of sprayed concrete lined (SCL) tunnel junctions at Liverpool Street Crossrail station

Sprayed concrete linings (SCL) offer a versatile method of tunnel construction, particularly in regard to forming junctions since the lining acts as a shell structure which can redistribute the stresses around the opening efficiently. This process is easy to understand conceptually but it is much more difficult to illustrate in calculations. Conventional calculation methods make a number of far-reaching simplifications such as the assumption of linear elastic behaviour in the lining. This often leads to overly conservative designs and a residual concern over the loads in the lining. This study compares detailed measurements of strains recorded by distributed fibre optic sensors at a pair of junctions on the Crossrail project in London with a sophisticated numerical model of these tunnels. Having demonstrated that the results of the numerical model are broadly consistent with this unique set of field data, a variety of influences on the model have been examined. This includes the excavation sequence, the constitutive model for the lining and adjacent structures. The results indicate significant scope for the improvement of SCL junction design. Future papers will present the more results from other parts of this study along with their implications for the design of tunnel junctions.

Substantiation of the Escalator Tunnel Construction Technology Based on the Results of Field Research

Purpose. The authors aim to substantiate a new technology for the construction of an escalator tunnel in Ukraine based on the results of field studies performed as part of surveying measurements during the construction of the inclined run of the Dnipro metro. Methodology. The article analyzes the main technology of the escalator tunnel construction, which was based on the development of an inclined working from top to bottom with preliminary preparation of the massif by means of artificial soil freezing. Several cases of application of the bottom-up escalator tunnel construction method using the New Austrian Tunneling Method (NATM), which is successfully used in metro of other countries, are considered. The main principle of the method is that a shotcrete system is used as a temporary (primary) support, and a reinforcement system with monolithic concrete is used as a permanent support. Findings. The authors analyzed the peculiarities of the escalator tunnel excavation of the Dnipro metro by the Turkish company «Limak» in 2017–2018. It was noted that the excavation was carried out from the bottom up in conditions of strong rock (plagiogranite) using drilling and blasting operations. The characteristic results of field studies during drilling and blasting operations in the process of developing the calotte are analyzed. On the basis of these data, it is possible to trace the tendency to the appearance of minor overburden during sinking. The value of the deformed state (displacement of the contour of the designed casing) is within the normative limits, which indicates the effective use of these works within the framework of NATM. It is proved that in the conditions of military operations, the technology of building an escalator tunnel from the bottom up is a guarantee of the safety of workers and equipment. Originality. The results of the scientific work presented in the article make it possible to determine the level of deformed state during the excavation of the escalator tunnel of the Dnipro metro in hard rocks. During the field studies, the dependences of deformation of plagiogranite in the inclined bore were obtained. Practical value. An alternative technology for the construction of a bottom-up escalator tunnel based on NATM with the provision of normative deformation of the surrounding rock mass is substantiated.

Experimental and Numerical Investigation into Full-Scale Model of New Type Assembled Integral Utility Tunnel

This article summarizes the current construction methods of prefabricated utility tunnels. (1) The proposed cast-in-place utility tunnel project was used as a background for this study. (2) The original cast-in-place structure was divided into components, and the connection methods of prefabricated composite slabs and mortise and tenon joints were used to propose a new type of prefabricated concrete utility tunnel construction method. After completing the design of the new prefabricated utility tunnel, a numerical simulation analysis of the actual stress situation of the utility tunnel was carried out using ABAQUS finite element software to verify the overall structural performance of the assembled utility tunnel. In addition, after completing the construction of the full-size model of the dual chamber, static load tests were carried out. (3) The test used the method of monotonic static bidirectional loading with a central hydraulic jack and tensioned steel strands, analyzed the cracks, deformation curves, and stress-strain of steel bars and concrete of the overall structure of the utility tunnel, and (4) verified the feasibility of the new assembled integral utility tunnel.

Development of a PLSR-BRT Model for Predicting the Performance of Tunnel Boring Machines

Scientific prediction of the penetration rate (PR) of tunnel boring machines (TBMs) is of great significance to the selection of tunnel construction methods, the prediction of construction progress, and the evaluation of benefits. In view of the high nonlinearity, fuzziness, and complexity of the TBM excavation process, this paper attempts to present a new algorithm that integrates partial least squares regression (PLSR) with boosted regression trees (BRT) for predicting the PR of TBMs. For this purpose, 150 datasets were obtained from the Lanzhou water conveyance tunnel project in China. Six impact factors were selected as the input layers of the proposed model by single-factor correlation analysis. To develop the PLSR-BRT model, two principal components of the influencing parameters were extracted via the PLSR method, and the BRT algorithm was employed to establish the predictive model. In addition, other models such as PLSR back propagation neural network (BPNN), BRT, PLSR, support vector regression (SVR), and artificial neural network (ANN) were adapted for use in this problem to verify the predictive accuracy of the proposed model. The results demonstrated that the PLSR-BRT model achieved the best predictive performance compared with the other models, with coefficient of determination value (R2) and root mean square error (RMSE) of 0.96 and 1.78, respectively, for the testing set. The PLSR-BRT model can maximally avoid both overfitting and inadequate fitting. In view of engineering applications, the complexity and redundancy of the field dataset can be solved via reducing the dimensionality of input parameters, and the training samples could be expanded by a boosted method so that the discontinuously acquired geological parameters are unable to restrain the model performance. This method serves as an effective approach for TBM PR prediction and has excellent potential for a variety of scientific and engineering applications.

An integrated framework for improving the efficiency and safety of hydraulic tunnel construction

Drilling and blasting is the most flexible tunnel construction method considering the excavation of tunnel size and shape. Schedule and safety are two critical issues for project stakeholders during construction. To evaluate construction quality, various tools such as Building Information Modelling (BIM), schedule simulation, and numerical analysis are commonly employed. However, in current practices, these processes are often independent of each other, requiring data conversion and operation between multiple platforms. In this paper, we present a novel integrated framework for improving the safety and efficiency of hydraulic tunnel construction. To this end, a geometric tunnel model with time attribute is created, which connects the schedule information obtained by construction simulation via secondary development. Then a numerical simulation method coupled with construction schedule is introduced to the integrated framework, which can automatically process the numerical model and perform analysis and calculation combined with the schedule information. In addition, this paper proposes a parameterization method of the rock bolt numerical model to realize the evaluation of different support schemes. The proposed method can avoid tedious manual operations to reduce possible errors. Finally, we propose a multistep prediction model of surrounding rock deformation based on Long Short-Term Memory (LSTM). The framework integrates the above functions via secondary development, scripting, and other technologies, and demonstrates the reliability of the framework with a tunnel project. The proposed integrated framework provides an intuitive and efficient tunnel construction management method hence promoting the information flow of multiple participants and multiple professionals in tunnel construction and providing decision support.

A novel consensus reaching method for MCGDM in social network with intuitionistic grey linguistic numbers

PurposeThe existing consensus reaching mechanisms ignore the influence of social triangle structure on the decision-makers’ (DMs') weights, and the consensus reaching process (CRP) fails to fully reflect the DMs' subjectivity and can be time consuming and costly. To solve these issues, a novel CRP for multi-criteria group decision-making (MCGDM) problems with intuitionistic grey linguistic numbers (IGLNs) is proposed in this paper.Design/methodology/approachFirst, a weight calculation method is proposed by analysing the triangle structure of DMs' social network and scale of adjacent nodes. Then, a consensus degree index based on three-level polygon area is defined and applied to identify the inconsistent DMs. Finally, the feedback mechanism based on particle swarm optimisation (PSO) algorithm under grey linguistic environment is developed, where subjective trust relationships in social network is utilised to determine the adjustment coefficient.FindingsThe advantages of the proposed method are highlighted by two practical applications of the evaluation of tunnel construction method and the selection of a hotel for the centralised isolation. Comparision analysis and numerical simulation are performed to reveal the effectiveness and applicability of the method.Practical implicationsThe proposed model can not only reflect the effect of triangle structure in social network on DMs' weights, but also reduce the time and cost of decision-making.Originality/valueThe main contribution of this paper is to propose a new MCGDM model based on intuitionistic grey linguistic numbers, which can handle the problem of inconsistency of information more effectively.

Surface control techniques for tunnels in karst areas under airport taxiways

Under the conditions of karst development and soft upper and hard lower strata, ground-settlement control for tunnels under airport taxiways is stricter than for ordinary tunnels. Tunnel construction methods and karst disposal measures are also important. These are engineering problems that need to be solved urgently to ensure the safe passage of tunnels under airport taxiways. Taking the intercity railway tunnel under taxiways T3 and T4 of Guangzhou Baiyun international airport as a case study, theoretical analysis and field tests on karst treatment measures and ground-settlement control measures were conducted. Karst treatment measures and a pile support plate (PSP) structure have been proposed to support the taxiways. The effect of the system was analysed numerically method and on-site surface settlement was monitored. The maximum monitored settlement of T3 and T4 taxiway surfaces was 5.90 mm and the differential settlement was 0.12‰. The numerical results provided a similar value and did not exceed the settlement control standard for airport taxiways. The key technologies for the construction of tunnels under airport taxiways in karst areas and upper soft and lower hard strata are presented, karst disposal measures are summarised and the PSP protection system is described. The results provide reference information for similar projects.

Intelligent Identification and Construction System of Prefabricated Tunnel Structure Based on BIM Technology

In order to make up for the problems of low production efficiency, high labor cost, serious environmental pollution, and low degree of informatization of traditional tunnel construction method, an intelligent identification building system of prefabricated tunnel structure is proposed. Based on BIM Technology and integrating advanced concepts and technologies in the construction industry and management field, an intelligent construction system of prefabricated tunnel structure based on BIM is proposed, the characteristics, functions, and values of each component are introduced, and the overall architecture of the system is established, which can provide technical support for the whole life cycle construction, operation, and maintenance of prefabricated railway tunnel. Only 68% of architectural designers know BIM Technology, while only 4% of designers really use or are using BIM Technology to participate in prefabricated architectural design. Through this research, the use frequency of BIM can be greatly increased and work efficiency can be improved. To meet the requirements of railway tunnel construction for intelligent construction in the new era, the new technology and new ideas also lead the further scientific and technological innovation in tunnel engineering to a certain extent, which meets the actual needs of the development of intelligent railway construction technology and has a practical significance of improving quality and efficiency.

Statistics and construction methods for deep TBM tunnels with high geostress: A case study of Qinling Tunnel in Hanjiang-Weihe River Diversion Project

Rockbursts pose serious threats to the engineering safety. As a typical deep TBM tunnel with high geostress, the Qinling Tunnel of Hanjiang-Weihe River Diversion Project has encountered a large number of rockbursts. Based on this project, a detailed analysis of the rockburst data was used to investigate the size and locations of single rockfalls, and volume of a single blast. Moreover, the relationships between rockbursts and lithology, and between rockbursts and buried depth were established, and the form of rockburst damage was analysed. In addition, specific construction methods under different rockburst levels were summarised, drawing on the successful experience of this project. A method for replacing the cutter head under rockburst risk after long-distance tunnelling was also proposed.

Review on Tunnel Construction Method and Environmental Impact

unnel construction has become more common as the number of road construction projects in Malaysia has increased. The impacts on the environment and the safety of users are significant concerns during tunnel construction. This research aims to determine road tunnel construction technologies, environmental impacts, and best practices in road tunnel construction. This study was carried out by scoping the literature. The study starts with identifying the most relevant search keywords then examines the articles using quantitative and qualitative techniques. The four types of road tunnel construction discovered in the study are cut and cover, bore or mine tunneling, soft surface tunnelling, and hard rock tunnelling. Tunnels construction has significantly impact to the environment through various sources such as generation of construction waste material, sludge generation, wastewater generation, and noise and vibration. As a fundamental matter, one of the most important things to consider in any road tunnel construction project is a comprehensive examination of the suitability of the soil, surface, geology, and hydrology prior project development. Environmental impact assessment should be done to identify the environmental impact and appropriate mitigation measures. This study identifies five recommended practices for tunnel building that can be adopted sustainably. The first is a detailed investigation of soil, rock, and hydrological geology. It is to ensure the best techniques and approach to be implemented. The second, is an environmental impact assessment study need to be done before the project's implementation. The third is to choose the best available option for tunnel construction method by considering environmental impact and cost effective. The fourth is initiating stakeholder consultation to ensure people that will affected are informed. The fifth is continues monitoring to ensure the environmental impact is closely monitor before, during and after the tunnel construction.