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14 pages, 2942 KiB

Open AccessArticle

Upper Bound Limit Analysis of Deep Tunnel Face Support Pressure with Nonlinear Failure Criterion under Pore Water Conditions

by Zihan Yang, Yongxin Li and Jingshu Xu

Buildings 2024, 14(9), 2677; https://doi.org/10.3390/buildings14092677 - 28 Aug 2024

Cited by 1 | Viewed by 586

Abstract

Based on the nonlinear failure criterion and modified tangential technique, the upper bound solutions of the critical supporting pressure on the deep tunnel face were obtained under pore water pressure conditions. The influence of parameters on the critical supporting pressure and collapse range [...] Read more.

Based on the nonlinear failure criterion and modified tangential technique, the upper bound solutions of the critical supporting pressure on the deep tunnel face were obtained under pore water pressure conditions. The influence of parameters on the critical supporting pressure and collapse range was investigated according to the unlimited block failure mechanism. It was found that the upper bound solutions of the critical supporting pressure increase with the growth of the nonlinear coefficient and pore water pressure coefficient. The collapse range of the tunnel face scales out with the increase in the nonlinear coefficient and shrinks with an increasing pore water pressure coefficient. Moreover, with the increase in the nonlinear coefficient, the impact strength on critical supporting pressure and collapse range declines gradually. According to the calculated results, both the pore water pressure and nonlinear criterion factors have negative impacts on the stability of the tunnel face. Thus, more attention should be paid to these parameters to ensure face stability in deep tunnel construction. Full article

(This article belongs to the Special Issue Intelligent Risk Identification and Management in Urban Built Environment)

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14 pages, 5449 KiB

Open AccessArticle

Critical Face Pressure of a Tunnel Driven by a Shield Machine Considering Seismic Forces and Tunnel Shape Influence

by Yunfu Jia, Chengyuan Pei, Feng Liang and Tianzheng Li

Buildings 2024, 14(6), 1760; https://doi.org/10.3390/buildings14061760 - 11 Jun 2024

Cited by 1 | Viewed by 902

Abstract

Evaluating critical face pressure with high accuracy is an important topic for shield tunneling. The existing research focuses more on the influence of complex geological conditions or environmental factors, and there are few reports on the influence of tunnel shape on critical face [...] Read more.

Evaluating critical face pressure with high accuracy is an important topic for shield tunneling. The existing research focuses more on the influence of complex geological conditions or environmental factors, and there are few reports on the influence of tunnel shape on critical face pressure. In reality, the tunnel shape has a significant impact on the deformation zone in front of the tunnel face, which may lead to non-negligible differences in shield pressure. To fill this gap, an efficient analytical approach is proposed to estimate the critical face pressure considering different tunnel shapes in the framework of limit analysis. As earthquakes are potential threats to the tunnel face stability in seismically active regions, the seismic effect is also taken into account with the help of the pseudo-static method. Several cases with the same area but different tunnel shapes are investigated using the limit analysis method. A comparison with static analysis is given to highlight the influence of seismic forces on the tunnel face stability. The results show that the critical face pressures increase by 15.3% when the tunnel face shape changes from rectangular to circular, and by 23.5% when the horizontal seismic coefficient varies from 0 to 0.1. A further validation with a 3D finite difference method is performed with respect to four typical tunnel shapes considered in this study. Lastly, several stability charts are provided for a quick estimation of the critical tunnel face pressure subjected to seismic forces. It is concluded that the proposed method can be applied to a tunnel stability assessment of various cross-sections and is highly efficient compared with numerical simulations. Full article

(This article belongs to the Special Issue Intelligent Risk Identification and Management in Urban Built Environment)

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18 pages, 5164 KiB

Open AccessArticle

Research on Prediction of EPB Shield Tunneling Parameters Based on LGBM

by Wei Wang, Huanhuan Feng, Yanzong Li, Quanwei You and Xu Zhou

Buildings 2024, 14(3), 820; https://doi.org/10.3390/buildings14030820 - 18 Mar 2024

Cited by 1 | Viewed by 1584

Abstract

At present, the determination of tunnel parameters mainly rely on engineering experience and human judgment, which leads to the subjective decision of parameters and an increased construction risk. Machine learning algorithms could provide an objective theoretical basis for tunnel parameter decision making. However, [...] Read more.

At present, the determination of tunnel parameters mainly rely on engineering experience and human judgment, which leads to the subjective decision of parameters and an increased construction risk. Machine learning algorithms could provide an objective theoretical basis for tunnel parameter decision making. However, due to the limitations of a machine learning model’s performance and parameter selection methods, the prediction model had poor prediction results and low reliability for parameter research. To solve the above problems, based on a large number of construction parameters of a composite section subway in Shenzhen, this paper combined dimensionality reduction data with service analysis to optimize the selection process of shield tunneling parameters, and determined the total propulsion force, cutter head torque, cutter head speed, and advance rate as key tunneling parameters. Based on an LGBM algorithm and Bayesian optimization, the prediction model of key tunneling parameters of an earth pressure balance shield was established. The results showed that the average error of the LGBM model on the test set was 8.18%, the average error of the cutter head torque was 13.93%, the average error of the cutter head speed was 3.16%, and the average error of advance rate was 13.35%. Compared with the RF model, the prediction effect and the generalization on the test set were better. Therefore, an LGBM algorithm could be used as an effective prediction method for tunneling parameters in tunnel construction and provide guidance for the setting of tunneling parameters. Full article

(This article belongs to the Special Issue Intelligent Risk Identification and Management in Urban Built Environment)

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17 pages, 6388 KiB

Open AccessArticle

A Multiscale Method to Develop Three-Dimensional Anisotropic Constitutive Model for Soils

by Yu Tian, Hao Chen, Zijun Yao and Yufei Fang

Buildings 2024, 14(2), 307; https://doi.org/10.3390/buildings14020307 - 23 Jan 2024

Cited by 1 | Viewed by 1205

Abstract

A multiscale method is presented to develop a constitutive model for anisotropic soils in a three-dimensional (3D) stress state. A fabric tensor and its evolution, which quantify the particle arrangement at the microscale, are adopted to describe the effects of the inherent and [...] Read more.

A multiscale method is presented to develop a constitutive model for anisotropic soils in a three-dimensional (3D) stress state. A fabric tensor and its evolution, which quantify the particle arrangement at the microscale, are adopted to describe the effects of the inherent and induced anisotropy on the mechanical behaviors at the macroscale. Using two steps of stress mapping, the deformation and failure of anisotropic soil under the 3D stress state are equivalent to those of isotropic soil under the triaxial compression stress state. A series of discrete element method (DEM) simulations are conducted to preliminarily verify this equivalence. Based on the above method, the obtained anisotropic yield surface is continuous and smooth. Then, a fabric evolution law is established according to the DEM simulation results. Compared with the rotational hardening law, the fabric evolution law can also make the yield surface rotate during the loading process, and it can grasp the microscopic mechanism of soil deformation. As an example, an anisotropic modified Cam-clay model is developed, and its performance validates the ability of the proposed method to account for the effect of soil anisotropy. Full article

(This article belongs to the Special Issue Intelligent Risk Identification and Management in Urban Built Environment)

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17 pages, 13357 KiB

Open AccessArticle

Experimental Study on the Evolution Law of the Mechanical and Pore Characteristic Parameters of Set Cement under High- and Ultra-High-Temperature Treatments

by Yan Xi, Junhao Xing, Jiajia Feng, Congming Ma, Xiutian Yang, Yudong Tian and Xin Liu

Buildings 2024, 14(1), 303; https://doi.org/10.3390/buildings14010303 - 22 Jan 2024

Viewed by 1550

Abstract

Cement has been widely used as a structural material in many underground projects, and these projects often face high- or ultra-high-temperature environments, leading to the deterioration of the mechanical, porosity, and permeability properties of set cement, thereby increasing the risk of instability of [...] Read more.

Cement has been widely used as a structural material in many underground projects, and these projects often face high- or ultra-high-temperature environments, leading to the deterioration of the mechanical, porosity, and permeability properties of set cement, thereby increasing the risk of instability of underground structures. In response to this, two new temperature-resistant cement slurry systems were designed. Experiments were conducted on the changes in porosity and permeability of set cement after thermal treatment using low-field nuclear magnetic resonance technology (NMR), visual studies of pore and crack development were carried out using the argon-ion polishing field emission scanning electron microscopy (FE-SEM) and computed tomography (CT) methods. The research results show that as the thermal treatment temperature continued to rise, the compressive strength first increased (25 °C–200 °C) and then decreased (200 °C–600 °C). The porosity of the set cement first decreased (25 °C–115 °C) and then increased (115 °C–600 °C), and the penetration first slowly increased (25 °C–400 °C) and then rapidly increased (400 °C–600 °C). Visualization experiments were conducted on micro-cracks and the pore distribution of the set cement under high- and ultra-high-temperatures, which proved the evolution law of these characteristic parameters. The research results have vital reference significance for the protection of the structural stability of cement components when encountering high-temperature environments. Full article

(This article belongs to the Special Issue Intelligent Risk Identification and Management in Urban Built Environment)

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17 pages, 3495 KiB

Open AccessArticle

Effect of Rock Mass Disturbance on Stability of 3D Hoek–Brown Slope and Charts

by Jingshu Xu, Xinrui Wang, Pengfei Xie, Ruotong Wang and Dianchun Du

Buildings 2024, 14(1), 114; https://doi.org/10.3390/buildings14010114 - 31 Dec 2023

Viewed by 1517

Abstract

The present study performs a stability analysis of a three-dimensional (3D) rock slope in disturbed rock masses following the Generalized Hoek–Brown (GHB) failure criterion. The factor of safety (FoS) of the slope is derived and the optimal solution is captured combining [...] Read more.

The present study performs a stability analysis of a three-dimensional (3D) rock slope in disturbed rock masses following the Generalized Hoek–Brown (GHB) failure criterion. The factor of safety (FoS) of the slope is derived and the optimal solution is captured combining the limit analysis method and the strength reduction technique. It is indicated by the parametric analysis that the 3D geometric characteristics have a significant impact on slope stability such that FoS decreases sharply with the increase in the width-to-height ratio

B / H

within

0 < B / H \leq 2.0

and thereafter reaches a constant value asymptotically. The FoS decreases more than 60% linearly when the disturbance factor D increases from 0 to 1.0. Stability charts and slope angle weight factor f_β_{_3D} for 3D slopes are proposed to provide a convenient and straightforward approach to obtain the FoS solutions of 3D slopes. A case study was carried out to apply the stability charts on practical engineering cases, which showed that slope stability under two-dimensional (2D) plane strain will lead to conservative results, and a 3D stability analysis of slope is more appropriate, especially for a slope with a limited width. Full article

(This article belongs to the Special Issue Intelligent Risk Identification and Management in Urban Built Environment)

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18 pages, 6440 KiB

Open AccessArticle

Risk-Informed, Reliability-Driven Decision Support for Building Basement Systems

by Ashan Senel Asmone, Helapura Nuwanshi Yasodara Senarathne and Michael Yit Lin Chew

Buildings 2023, 13(11), 2737; https://doi.org/10.3390/buildings13112737 - 30 Oct 2023

Cited by 2 | Viewed by 1213

Abstract

A lack of consideration for maintainability at the planning/design stage of a construction project often results in inadequate decision-making and selection of design alternatives, which will likely lead to unproductive operational regimes riddled with frequent defects. This paper attempts to anchor the quantitative [...] Read more.

A lack of consideration for maintainability at the planning/design stage of a construction project often results in inadequate decision-making and selection of design alternatives, which will likely lead to unproductive operational regimes riddled with frequent defects. This paper attempts to anchor the quantitative risk analysis technique, Bayesian networks, as apt in predicting future operational defects based on the initial design alternatives by looking at specific case studies in building basement systems. Therefore, this paper aims to develop a comprehensive risk-informed, reliability-driven decision-making system. Central to this process is the implementation of a setup wherein a Bayesian Belief Network (BBN) operates as a powerful reliability engine. Concurrently, a risk matrix serves as a vital tool for facilitating risk-informed decision-making. This approach empowers stakeholders to make informed decisions regarding design choices while keeping maintainability at the forefront. It allows for maintainability to be practically used as an effective tool in buildings to lower the lifecycle cost. Furthermore, it is envisaged that this approach can be adopted in the construction industry globally for the prediction and diagnosis of defects, thereby facilitating risk-informed decision support. This study provides significant contributions to the building industry by providing a novel approach to a basement defect analysis, encouraging interdisciplinary collaboration among construction stakeholders, and assisting facility engineers and managers in properly determining maintenance requirements. Full article

(This article belongs to the Special Issue Intelligent Risk Identification and Management in Urban Built Environment)

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17 pages, 16018 KiB

Open AccessArticle

Buckling Analysis of a New Type of Double-Steering Prestressed Plate Column

by Yanying Li, Bailong Li, Xinsheng Yin and Zhiying Han

Buildings 2023, 13(10), 2574; https://doi.org/10.3390/buildings13102574 - 12 Oct 2023

Cited by 1 | Viewed by 1148

Abstract

A new type of dual-steering prestressed plate column is introduced. Compared to the previous prestressed strut column, this proposed column considers both bending and constraints at ends. The calculation results indicated that the support plate significantly improves the stable bearing capacity and buckling [...] Read more.

A new type of dual-steering prestressed plate column is introduced. Compared to the previous prestressed strut column, this proposed column considers both bending and constraints at ends. The calculation results indicated that the support plate significantly improves the stable bearing capacity and buckling performance of the core steel column. When compared to the proposed column, the bearing capacity of the three-transverse prestressed beam column is 1.51 times smaller, the single-transverse prestressed beam column is 2.43 times lower, and the non-prestressed column is 4.51 times smaller. Moreover, this study examines the influences of effective length, buckling mode, stress nephogram detail, and prestress value. It explores the possibility of implementing this new type of dual-steering prestressed plate column in practical engineering. In addition, the variety and mechanical models of prestressed columns are expanded and refined. Full article

(This article belongs to the Special Issue Intelligent Risk Identification and Management in Urban Built Environment)

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