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The purpose of the study is to quickly identify significant heterogeneity of surrounding rock of tunnel face that generally occurs during the construction of large-section rock tunnels of high-speed railways.

Relying on the support vector machine (SVM)-based classification model, the nominal classification of blastholes and nominal zoning and classification terms were used to demonstrate the heterogeneity identification method for the surrounding rock of tunnel face, and the identification calculation was carried out for the five test tunnels. Then, the suggestions for local optimization of the support structures of large-section rock tunnels were put forward.

The results show that compared with the two classification models based on neural networks, the SVM-based classification model has a higher classification accuracy when the sample size is small, and the average accuracy can reach 87.9%. After the samples are replaced, the SVM-based classification model can still reach the same accuracy, whose generalization ability is stronger.

By applying the identification method described in this paper, the significant heterogeneity characteristics of the surrounding rock in the process of two times of blasting were identified, and the identification results are basically consistent with the actual situation of the tunnel face at the end of blasting, and can provide a basis for local optimization of support parameters.

This paper aims to investigate the responses of single piles and pile groups due to tunneling-induced ground movements in a two-layered soil system. The analyses mainly focus on the additional single pile responses in terms of bending moment, lateral deflection, axial force, shaft resistance and pile settlement. Subsequently, a series of parametric studies were carried out to better understand the responses of single piles induced by tunneling. To give further understanding regarding the pile groups, a 2 × 2 pile group with two different pile head conditions, namely, free and capped, was considered.

Using the PLAXIS three-dimensional (3D) software, a full 3D numerical modeling is performed to investigate the effects of ground movements caused by tunneling on adjacent pile foundations. The numerical model was validated using centrifuge test data found in the literature. The relevance of the 3D model is also judged by comparison with the 2D plane strain model using the PLAXIS 2D code.

The numerical test results reveal that tunneling induces significant displacements and internal forces in nearby piles. The magnitude and distribution of internal forces depend mainly on the position of the pile toe relative to the tunnel depth and the distance between the pile and the vertical axis of the tunnel. As the volume loss increases from 1% to 3%, the apparent loss of pile capacity increases from 11% to 20%. By increasing the pile length from 0.5 to 1.5 times, the tunnel depth, the maximum pile settlement and lateral deflection decrease by about 63% and 18%, respectively. On the other hand, the maximum bending moment and axial load increase by about 7 and 13 times, respectively. When the pile is located at a distance of 2.5 times the tunnel diameter (Dt), the additional pile responses become insignificant. It was found that an increase in tunnel depth from 1.5Dt to 2.5Dt (with a pile length of 3Dt) increases the maximum lateral deflection by about 420%. Regarding the interaction between tunneling and group of piles, a positive group effect was observed with a significant reduction of the internal forces in rear piles. The maximum bending moment of the front piles was found to be higher than that of the rear piles by about 47%.

Soil is a complex material that shows differently in primary loading, unloading and reloading with stress-dependent stiffness. This general behavior was not possibly being accounted for in simple elastic perfectly plastic Mohr–Coulomb model which is often used to predict the behavior of soils. Thus, in the present study, the more advanced hardening soil model with small-strain stiffness (HSsmall) is used to model the non-linear stress–strain soil behavior. Moreover, unlike previous studies THAT are usually based on the assumption that the soil is homogeneous and using numerical methods by decoupled loadings under plane strain conditions; in this study, the pile responses have been exhaustively investigated in a two-layered soil system using a fully coupled 3D numerical analysis that takes into account the real interactions between tunneling and pile foundations. The paper presents a distinctive set of findings and insights that provide valuable guidance for the design and construction of shield tunnels passing through pile foundations.

The microseismic monitoring technique has great advantages on identifying the location, extent and the mechanism of damage process occurring in rock mass. This study aims to analyze distribution characteristics and the evolution law of excavation damage zone of surrounding rock based on microseismic monitoring data.

In situ test using microseismic monitoring technique is carried out in the large-span transition tunnel of Badaling Great Wall Station of Beijing-Zhangjiakou high-speed railway. An intelligent microseismic monitoring system is built with symmetry monitoring point layout both on the mountain surface and inside the tunnel to achieve three-dimensional and all-round monitoring results.

Microseismic events can be divided into high density area, medium density area and low density area according to the density distribution of microseismic events. The positions where the cumulative distribution frequencies of microseismic events are 60 and 80% are identified as the boundaries between high and medium density areas and between medium and low density areas, respectively. The high density area of microseismic events is regarded as the high excavation damage zone of surrounding rock, which is affected by the grade of surrounding rock and the span of tunnel. The prediction formulas for the depth of high excavation damage zone of surrounding rock at different tunnel positions are given considering these two parameters. The scale of the average moment magnitude parameters of microseismic events is adopted to describe the damage degree of surrounding rock. The strong positive correlation and multistage characteristics between the depth of excavation damage zone and deformation of surrounding rock are revealed. Based on the depth of high excavation damage zone of surrounding rock, the prestressed anchor cable (rod) is designed, and the safety of anchor cable (rod) design parameters is verified by the deformation results of surrounding rock.

The research provides a new method to predict the surrounding rock damage zone of large-span tunnel and also provides a reference basis for design parameters of prestressed anchor cable (rod).

Since 1960, many public–private partnership (PPP) projects have been implemented in Hong Kong. Some projects have been considered as very successful, whereas others are seen as less successful. Unfortunately, these success outcomes have remained abstract because they are not in quantifiable terms. This paper aims to develop a model that can quantify the success outcome of PPP projects in Hong Kong.

Both quantitative and qualitative research approaches were adopted for the study. First, a questionnaire survey was conducted with PPP practitioners in Hong Kong, and thereafter, the fuzzy synthetic evaluation technique was used to develop a project success index for PPP projects in Hong Kong. The Hong Kong Cross-Harbour Tunnel project was used as a case study to demonstrate the applicability of the pragmatic model.

The success index model developed consists of four unrelated success criteria groupings: cost effectiveness, quality of services and technical specification, environmental impact and long-term partnership. Further, the computed success index for the Cross-Harbour Tunnel project is 4.06, which indicates that the tunnel project has been highly successful.

The outputs of this study will enable PPP practitioners in Hong Kong to reliably evaluate the success levels of their projects. In addition, local practitioners can now compare the success levels of two or more PPP projects on the same basis.

Large displacement misalignment under the action of active faults can cause complex three-dimensional deformation in subway tunnels, resulting in severe damage, distortion and misalignment. There is no developed system of fortification and related codes to follow. There are scientific problems and technical challenges in this field that have never been encountered in past research and practices.

This paper adopted a self-designed large-scale active fault dislocation simulation loading system to conduct a similar model test of the tunnel under active fault dislocation based on the open-cut tunnel project of the Urumqi Rail Transit Line 2, which passes through the Jiujiawan normal fault. The test simulated the subway tunnel passing through the normal fault, which is inclined at 60°. This research compared and analyzed the differences in mechanical behavior between two types of lining section: the open-cut double-line box tunnel and the modified double-line box arch tunnel. The structural response and failure characteristics of the open-cut segmented lining of the tunnel under the stick-slip part of the normal fault were studied.

The results indicated that the double-line box arch tunnel improved the shear and longitudinal bending performance. Longitudinal cracks were mainly distributed in the baseplate, wall foot and arch foot, and the crack position was basically consistent with the longitudinal distribution of surrounding rock pressure. This indicated that the longitudinal cracks were due to the large local load of the cross-section of the structure, leading to an excessive local bending moment of the structure, which resulted in large eccentric failure of the lining and formation of longitudinal cracks. Compared with the ordinary box section tunnel, the improved double-line box arch tunnel significantly reduced the destroyed and damage areas of the hanging wall and footwall. The damage area and crack length were reduced by 39 and 59.3%, respectively. This indicates that the improved double-line box arch tunnel had good anti-sliding performance.

This paper adopted a self-designed large-scale active fault dislocation simulation loading system to conduct a similar model test of the tunnel under active fault dislocation. This system increased the similarity ratio of the test model, improved the dislocation loading rate and optimized the simulation scheme of the segmented flexible lining and other key factors affecting the test. It is of great scientific significance and engineering value to investigate the structure of subway tunnels under active fault misalignment, to study its force characteristics and damage modes, and to provide a technical reserve for the design and construction of subway tunnels through active faults.

Uncertainty, a state of unknowing linked to threats and opportunities, is a key characteristic of megaprojects, making it challenging for government officials and politicians to decide on their initiation. For them, implementation by the private sector adds an extra layer of complexity and uncertainty to megaproject planning. In this context, only a few studies have focussed on governing and the mobilization of uncertainty arguments in communication between government actors and private developers either in favour of or against megaprojects. The purpose of this article is to shed light on how private megaproject proposals progress towards political acceptance or rejection in public decision-making.

This process of public decision-making on private megaproject proposals is examined in the case of the Helsinki–Tallinn undersea rail tunnel. In line with the interpretive research tradition, the authors’ study draws on a qualitative methodology underpinned by social constructionism. The research process can be characterized as abductive.

The authors’ findings suggest that while public decision-making on megaprojects is a conflictual and dynamic process, some types of uncertainty are relatively more important in affecting the perceived feasibility of the projects in the eyes of public sector decision-makers.

This study contributes to the debate on uncertainty management in megaprojects, proposing a new type of uncertainty – uncertainty about privateness – which has not been explicitly visible thus far.

The purpose of this paper is to develop a life cycle risk management framework for public private partnership (PPP) infrastructure projects that lead to the realization of value for money and balance of interests between different partners including the public and end users.

This paper draws on extensive theoretical research and literature reviews, coupled with case study methodologies. A comprehensive review of current literature in the field was first carried out. Then three PPP infrastructure projects, two from Australia and one from China, are studied to scrutinize reasons leading to their dilemma and articulate the valuable lessons learnt in relation to risk analysis and mitigation.

The paper found that properly assessing risks (financial, government's political and public's acceptance/rejection risks), ensuring value for money and protecting the public (and end users') interests are essential in PPP infrastructure projects and this can only be achieved through optimal risk identification, assessment, allocation and management from a life cycle perspective and balanced interests between the Government/public and private partners as well as product end users.

The paper was limited to proposing the framework; therefore the next step should be testing the framework.

The framework proposed in this paper should be practical and useful for professionals in managing the risks associated with the procurement of PPP infrastructure projects.

The PPP method has been increasingly used to procure large‐scale infrastructures such as freeways, railways, tunnels and bridges worldwide. While there have been many successful PPP projects, unsuccessful cases abound and studying them can help people better manage the risks in future PPP infrastructure projects. To ensure the success of PPP infrastructure projects, it is important for all partners to manage the risks from a project life cycle perspective, in which risks are identified and assessed in the earliest possible project stage and are allocated to the parties who are in the best position to control them. Furthermore, it is also important to continuous monitor the risks and develop proactive risk respond strategies throughout the project life cycle. To this end, this paper provides a life‐cycle risk management framework for PPP infrastructure projects.

This study aims to research the large cross-section tunnel stability evaluation method corrected after considering the thickness-span ratio.

First, taking the Liuyuan Tunnel of Huanggang-Huangmei High-Speed Railway as an example and taking deflection of the third principal stress of the surrounding rock at a vault after tunnel excavation as the criterion, the critical buried depth of the large section tunnel was determined. Then, the strength reduction method was employed to calculate the tunnel safety factor under different rock classes and thickness-span ratios, and mathematical statistics was conducted to identify the relationships of the tunnel safety factor with the thickness-span ratio and the basic quality (BQ) index of the rock for different rock classes. Finally, the influences of thickness-span ratio, groundwater, initial stress of rock and structural attitude factors were considered to obtain the corrected BQ, based on which the stability of a large cross-section tunnel with a depth of more than 100 m during mechanized operation was analyzed. This evaluation method was then applied to Liuyuan Tunnel and Cimushan No. 2 Tunnel of Chongqing Urban Expressway for verification.

This study shows that under different rock classes, the tunnel safety factor is a strict power function of the thickness-span ratio, while a linear function of the BQ to some extent. It is more suitable to use the corrected BQ as a quantitative index to evaluate tunnel stability according to the actual conditions of the site.

The existing industry standards do not consider the influence of buried depth and span in the evaluation of tunnel stability. The stability evaluation method of large section tunnel considering the correction of overburden span ratio proposed in this paper achieves higher accuracy for the stability evaluation of surrounding rock in a full or large-section mechanized excavation of double line high-speed railway tunnels.

The purpose of this paper is to apply the theory of sociomateriality to exhibit how the social and material are entangled and (re)configured over time and in practice in a particular organization of study.

The authors conduct an ethnographic case study of the North-South metro line project in Amsterdam and use the methods of participant-observation, in-depth interviewing and a desk study.

The authors showcase the process of sociomaterial entanglement by focussing on the history and context of the project, the agency and performativity of the material and sociomaterial (re)configuration via ritual performance. The authors found the notion of performativity not only concern the enactment of boundaries between the social and material, but also the blurring of such boundaries.

Sociomateriality theory remains difficult to grasp. The implication is the need to provide new lenses to engage this theory empirically.

The authors provide a multi-layered lens for organization researchers to engage sociomateriality theory at a contextual, organizational and practice level.

Insights from a historical and contextual perspective can help practitioners to become aware of the diverse and dynamic ways in which social and material entities are entangled and (re)configured over time and in practice.

The authors provide a unique empirical account to exhibit the entanglement and (re)configuration between the social and material in a particular organization of study. This paper studies a tangible organizational setting whereas prior research in sociomateriality mainly focussed on routines in IT and IS. Finally, the authors suggest the ethnographic method to study sociomaterial entanglement from a historical and contextual perspective.

This paper aims at the problem of surrounding rock excavation damage zone of tunneling in the rich water region, this paper aims to propose a new seepage-stress-damage coupling model and studied the numerical algorithm. This reflects the characteristics of rock damage evolution, accompanied by plastic flow deformation and multi-field interaction.

First of all, rock elastoplastic damage constitutive model based on the Drucker–Prager criterion is established, the fully implicit return mapping algorithm is adopted to realize the numerical solution. Second, based on the relation between damage variation and permeability coefficient, the rock stress-seepage-damage model and multi-field coupling solving iterative method are presented. Finally, using the C++ language compiled the corresponding programs and simulated tunnel engineering in the rich water region.

Results show that difference evolution-based back analysis inversed damage parameters well, at the same time the established coupling model and calculating program have more advantages than general conventional methods. Multiple field coupling effects should be more considered for the design of tunnel support.

The proposed method provides an effective numerical simulation method for the construction of the tunnel and other geotechnical engineering involved underground water problems.