Tunnelling and Underground Space Technology最新文献

{"title":"Feasibility analysis of EICP technique for reinforcing backfill layer behind TBM tunnel linings based on model tests","authors":"Ming Huang ,&nbsp;Qiwu Jiang ,&nbsp;Kai Xu ,&nbsp;Chaoshui Xu","doi":"10.1016/j.tust.2024.106172","DOIUrl":"10.1016/j.tust.2024.106172","url":null,"abstract":"<div><div>In tunnelling using tunnel boring machine (TBM), the surrounding rocks are typically supported by precast lining segments, pea-gravel backfilling and grouting. The compactness of the backfill layer is critical for ensuring the safety of the tunnel construction. However, poor fluidity of cement generally leads to uneven grouting effects, resulting in lower density in certain areas of the backfill layer. In contrast, enzyme-induced carbonate precipitation (EICP) is an environmentally friendly and sustainable technique which has superior mobility and diffusivity compared to cement. To investigate the reinforcement effects of EICP technique on backfill layer, a series of bio-cemented sand column tests and model tests were conducted in this study. The optimal working range of pea gravel and sand for effective bio-cementation were determined by comparing the permeability, unconfined compressive strength (<em>UCS</em>), calcium carbonate content (<em>CCC</em>), and wave velocity of bio-cemented sand columns. The effects and homogeneity of reinforcement based on model tests were assessed by point load tests, wave velocity measurements, and calcium carbonate content evaluations. The model tests with different grouting hole layout density were conducted to obtain the optimal hole placement scheme. The column test results demonstrated that the optimal working range of pea gravel to sand ratio for effective bio-cementation is 1.25–1.5. As the number of grouting cycles increases, the point load strength, wave velocity, <em>CCC</em> and <em>UCS</em> of the specimens increase while the permeability of the specimens decreases. The point load strength of bio-cemented specimens could reach up to 16.53 MPa, while the permeability was reduced by three orders of magnitude compared with that of untreated specimens. The EICP has been demonstrated to be an effective technique capable of improving the compactness and strength of the backfill layer, with aggregates effectively cemented by calcium carbonate generated. The model test results demonstrated that the full-coverage arrangement hole scheme achieves uniform cementation, while the space arrangement hole scheme produces concentrated CaCO₃ near grouting holes. Furthermore, a new and improved grouting scheme is proposed based on the model test results. The data obtained in this study offer valuable references for the reinforcement of the backfill layer in TBM tunnelling using the EICP technology.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"155 ","pages":"Article 106172"},"PeriodicalIF":6.7,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on induced flow patterns and inlet velocity in inclined tunnel fire with natural ventilation","authors":"Xiaofeng Chen ,&nbsp;Jiangdong Li ,&nbsp;Yiling Ni ,&nbsp;Zhirong Liang ,&nbsp;Hangqiang Ding ,&nbsp;Lei Liu ,&nbsp;Xin Zhang ,&nbsp;Ke Wu ,&nbsp;Tianhang Zhang","doi":"10.1016/j.tust.2024.106188","DOIUrl":"10.1016/j.tust.2024.106188","url":null,"abstract":"<div><div>Inclined tunnels serve as a vital role in modern urban transportation networks. Nevertheless, the height-induced stack effect caused by the tunnel inclination during tunnel fires, results in smoke movement with multi-directional flow patterns, thus making the smoke flow in a very complicated manner. This study investigates the inlet ventilation velocity with flow field characteristics analysis for inclined tunnel fires under natural ventilation. Three flow patterns (i.e. “bidirectional flow”, “transitional flow”, and “unidirectional flow”) are clearly identified according to different airflow directions and smoke stratification. Moreover, theoretical analysis reveals that the flow patterns are principally governed by the interactive effects of thermal buoyancy (or fire HRR) and inertia forces (or induced velocity) concurrently. Herein, a modified Richardson number <em>Ri</em>', which essentially reflects the ratio of buoyant effect to inertial effect, has been proposed to determine the flow patterns in the inclined tunnel fires. Specifically, when <em>Ri</em>' &lt; 1.91, the airflow inertia force dominates the flow field structure, which causes the fire smoke to be a unidirectional flow with the longitudinal ventilation flow, and thus forms well-mixed gas. As <em>Ri</em>' increases, the buoyant effect becomes more prominent, which triggers the intermittent mixing regime occurred with fire smoke in induces a transitional flow state and partial stratification. When <em>Ri</em>' increases to 17.57, the buoyancy is predominant and leads the fire smoke to be complete stratification. In this case, the fire smoke and entrained air flow in opposite directions, resulting in a bidirectional flow within the tunnel. In addition, it is found that the inlet ventilation velocity increases with the increase of slope or tunnel length, but remains relatively unchanged by their combined influence under a fixed absolute tunnel height difference. Finally, considering the stratification characteristic in three flow patterns, a semi-empirical correlation to estimate the stack effect-induced velocity has been proposed. The proposed framework is validated by comparing with multi-scale experimental and numerical results from previous major studies. The research findings reveal the formation mechanism of the multi-directional flow patterns in inclined tunnel fires, which resolve the smoke transportation characteristics and illustrate the smoke flow dynamics intrinsically.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"155 ","pages":"Article 106188"},"PeriodicalIF":6.7,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new type of rockbolt model in 3D FDEM and its application to tunnel excavation","authors":"Chenglei Du ,&nbsp;Yong Cheng ,&nbsp;Quansheng Liu ,&nbsp;Zitao Cheng ,&nbsp;Yiwei Liu ,&nbsp;You Lu ,&nbsp;Haitao Jiang","doi":"10.1016/j.tust.2024.106210","DOIUrl":"10.1016/j.tust.2024.106210","url":null,"abstract":"<div><div>Rockbolt is a common support method in underground tunnel engineering, used to enhance the strength of rock mass and improve the stability of surrounding rock. In this paper, the three-dimensional (3D) FDEM method is employed to study the influence of rockbolts on the deformation and crack evolution of surrounding rock in tunnel engineering. Firstly, the CUDA-based GPU parallel 3D FDEM algorithm is briefly described, and its calculation process is summarized. At the same time, the contact search grid partitioning algorithm is optimized to address the problem of program crashes caused by grid memory overflow. Subsequently, a new rockbolt characterization method suitable for 3D FDEM algorithm is proposed, and the calculation process and constitutive equation of the new rockbolt algorithm are described in detail. The accuracy and feasibility of the new rockbolt algorithm are successfully verified by the pull-out test model and the three-point test model. Next, the numerical simulation of TBM tunnel project is carried out to study the deformation behavior and crack evolution path of surrounding rock after tunnel excavation. The results show that the vertical displacement of surrounding rock at the top of rockbolt tunnel model is greatly reduced, the crack development process is slowed down and the number of cracks is reduced. Finally, the influence of rockbolt row spacing and length on the deformation and crack propagation of surrounding rock is discussed. It is found that as the spacing decreases or the rockbolt length increases, the number of cracks in the surrounding rock gradually decreases, and the vertical displacement at the top of the surrounding rock gradually reduces. This study is helpful to understand the influence of rockbolts on the stability of surrounding rock, especially in tunnel engineering, it is of great significance for adjusting the rockbolt scheme under adverse geological conditions.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"155 ","pages":"Article 106210"},"PeriodicalIF":6.7,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Recognition of formation characteristics based on vibration signals in shield tunneling","authors":"Weimin Yang ,&nbsp;Zhongdong Fang ,&nbsp;Meixia Wang ,&nbsp;Jing Wang ,&nbsp;Jianjun Bai","doi":"10.1016/j.tust.2024.106199","DOIUrl":"10.1016/j.tust.2024.106199","url":null,"abstract":"<div><div>Shield machines are widely used in the construction of urban subway tunnels. Clear geological conditions are the prerequisite for safe and efficient shield tunneling. The vibration signal generated by the disc cutter cutting the rock contains rich information during the shield tunneling process. This paper analyzes the basic characteristics of vibration generated by the interaction between the disc cutter and the rock through theoretical calculation and numerical simulation. By measuring the shield vibration data under different surrounding rock strength on site and extracting the main characteristic indicators, a method is established relying on the BP neural network model for identifying the surrounding rock strength of the excavation face, which is characterized by the time domain-frequency domain of the vibration signal and successfully applied in the Jinan Metro Line 6 project. The research results show that the vibration frequency of the disc cutter force is concentrated at 0–25 Hz and 40–60 Hz, and the rock strength mainly affects the vibration amplitude of the disc cutter. The vibration signal characteristics generated during shield tunneling are highly sensitive to the surrounding rock strength, which is manifested as the greater the surrounding rock strength, the more obvious the time domain characteristic response of the vibration signal, and the more concentrated the main frequency of the IMF component. The accuracy of the model established in this paper for identifying the surrounding rock strength of excavation face is 98.88 %, and good application effects have been achieved in engineering.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"155 ","pages":"Article 106199"},"PeriodicalIF":6.7,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of bending stiffness and interface roughness on tunnel-embedded wall interaction","authors":"Jingmin Xu ,&nbsp;Luorui Zheng ,&nbsp;Zehui Yu ,&nbsp;Yan Li ,&nbsp;Guojun Cai","doi":"10.1016/j.tust.2024.106209","DOIUrl":"10.1016/j.tust.2024.106209","url":null,"abstract":"<div><div>In urban area tunnelling projects, preventing the adverse effects of tunnel construction on nearby structures often involves the use of embedded walls or piles. Designing the key parameters of these embedded structures is challenging due to the complex interaction between the soil and the structure. This paper presents a numerical investigation into the effects of embedded wall bending stiffness and soil-wall interface roughness on tunnel-wall interaction in sandy ground. Three dimensional numerical models were developed to simulate tunnel construction near an embedded wall with varying parameters, with sand behaviour simulated using a hypoplastic constitutive model calibrated by element tests and centrifuge models. The findings reveal that a decrease in interface roughness enhances the wall’s effectiveness in reducing tunnelling-induced settlements, while a decrease in wall bending stiffness reduces its performance in mitigating surface settlements and increases the wall bending moment. Based on the results, an improved design chart was developed by introducing correction coefficients for wall depth, taking into account the effects of wall stiffness and interface roughness on the wall’s efficiency in reducing tunnelling-induced settlements. This chart aims to assist engineers in quickly determining the preliminary horizontal locations and depths of embedded walls, ensuring both safety and effectiveness in selecting the depth and horizontal position of the embedded wall relative to the tunnel. These findings provide valuable guidance for the practical design and implementation of protective measures in urban excavation projects.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"155 ","pages":"Article 106209"},"PeriodicalIF":6.7,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Feasibility study of an adjustable-power laser cutting head for TBM applications: Focus on rock fragmentation efficiency and energy consumption","authors":"Kui Zhang ,&nbsp;Shangjun Xiao ,&nbsp;Wangwang Liu ,&nbsp;Dinghua Wang ,&nbsp;Gaofeng Zhang","doi":"10.1016/j.tust.2024.106155","DOIUrl":"10.1016/j.tust.2024.106155","url":null,"abstract":"<div><div>Mechanical rock-breaking tools generally perform poorly in cutting. To meet the “double carbon” target, it is important to reduce the consumption of metal materials and the waste of metallurgical energy. These issues are often caused by the frequent failures of rock-breaking tools in extreme geological formations. Such formations are characterized by high ground stress, high rock strength, and high quartz content. To address this, research has been conducted to support efficient rock breaking by full-face tunnel boring machines (TBMs) using disc cutters. This research includes establishing a laser theoretical model, designing a prototype laser cutting head, proposing a laser-assisted rock-breaking mode, and validating its feasibility. Initially, the introduction of a perforated spherical concave lens was proposed without altering the basic components of traditional laser cutting systems. This lens was aimed to improve the beam shaping principle of straight round lasers, thus suggesting a new adjustable power density distributed laser theoretical model. Subsequently, the structure of the prototype distributed laser cutting head was designed, and an integration scheme with the existing TBM cutterhead cutting system was provided. Based on the disc cutter rock-breaking mechanism, a laser pre-cutting groove-assisted adjacent disc cutters rock-breaking mode was proposed. Later, to analyze the rock-breaking effects of distributed lasers, on one hand, an improved plan for the laser cutting head optical assembly was proposed and simulated for verification; on the other hand, a laser rock-breaking experimental platform was further set up, and the rock-breaking effects of straight round/distributed lasers were compared and analyzed to determine the optimal object distance for subsequent experiments. Finally, experiments on disc cutter penetration into rock samples irradiated by straight round/distributed lasers under different distances from the cutter to the groove (<em>DCG</em>) were conducted. By comparing and analyzing the macroscopic rock fragmentation phenomena and the energy consumption of disc cutter penetration into rock, the feasibility of the new rock-breaking mode was preliminarily verified. The research results show that distributed lasers can fundamentally suppress the formation of vitreous glaze by reducing the laser power density in the outer non-core areas. By converting traditional straight round lasers into distributed lasers, the energy consumption during the penetration of tools into rock can be significantly reduced Additionally, the optimal <em>DCG</em> is increased. Compared to the traditional disc cutter rock-breaking mode, the proposed rock-breaking mode offers advantages such as better rock-breaking effects, lower energy consumption, and fewer required laser cutting heads and disc cutters.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"155 ","pages":"Article 106155"},"PeriodicalIF":6.7,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637882","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental study on the structural performance of RCP rehabilitation by spraying method under preloading","authors":"Chunliang He ,&nbsp;Shun Dong ,&nbsp;Jieyao Li ,&nbsp;Jiajie Liao ,&nbsp;Yingjie Wei ,&nbsp;Baosong Ma ,&nbsp;Sheng Huang","doi":"10.1016/j.tust.2024.106218","DOIUrl":"10.1016/j.tust.2024.106218","url":null,"abstract":"<div><div>In this study, an investigation was conducted on the rehabilitation of longitudinally cracked reinforced concrete pipes (RCPs) under preloaded conditions using the spraying method, based on TEB tests. The effects of sustaining preload and not sustaining preload on the performance of the rehabilitated pipes were examined, alongside the relationship between external loads and pipe displacement, strain, and cracks. The results revealed that the bearing capacity of the rehabilitated pipe increased by 5.6% in Specimen B, which was unloaded after preload, and by 22.7% in Specimen C, which maintained preload, compared to the pre-rehabilitation pipe. Compared with Specimen B, the ultimate bearing capacity of the repaired pipe in Specimen C increased by 12.8%, although the displacement at failure was significantly reduced. The failure of the repaired pipe-lining structure primarily occurred through longitudinal cracking and interfacial detachment of the lining. The application of spray lining improves the structural performance of damaged pipe, especially for specimens that maintain preloading.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"155 ","pages":"Article 106218"},"PeriodicalIF":6.7,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Longitudinal and circumferential bending moment responses of dislocated concrete pipes rehabilitated with CIPP liners under traffic loads","authors":"Hongyuan Fang ,&nbsp;Jiayang Sun ,&nbsp;Bin Li ,&nbsp;Xueming Du ,&nbsp;Niannian Wang ,&nbsp;Danyang Di ,&nbsp;Kejie Zhai","doi":"10.1016/j.tust.2024.106222","DOIUrl":"10.1016/j.tust.2024.106222","url":null,"abstract":"<div><div>The dislocation of concrete pipe joints, caused by factors such as uneven settlement and surface loads, can lead to structural deterioration and even failure of the pipeline. Addressing how to repair such pipelines to enhance their disaster resistance and resilience is a critical issue. This study focuses on Bell &amp; Spigot dislocated concrete pipes, conducting a full-scale model box experiment on the bending moment responses of dislocated pipes before and after Cured-In-Place Pipe (CIPP) rehabilitation under various burial depths. Additionally, a 3D finite element model was constructed to analyze the interaction between the dislocated concrete pipes and the surrounding soil, considering burial depth, load position, dislocated forms, flexural modulus of CIPP liner, and the liner thickness. A comparison of finite element (FE) model predictions and experimental measurements was made for CIPP liners at different burial depths, validating the reliability of the simulation results. Building on this, the study explores the influence of various factors on the longitudinal and circumferential bending moment responses of the dislocated concrete pipes before and after CIPP rehabilitation. Key findings indicate that at a burial depth of 0.5 m, the pipe experiences a deformation tendency with tension on the upper side and compression on the lower side. At burial depths of 1.0 m and 1.5 m, the pipe exhibits a deformation tendency with compression on the upper side and tension on the lower side. When the traffic load is positioned directly above the dislocated joint, the peak values of the longitudinal bending moments for the left pipe (P2) and right pipe (P3) adjacent to the dislocated joint increase by approximately 64 % and 137 %, and 74 % and 234 %, respectively, compared to when the traffic load is applied at the spigot and bell. The longitudinal bending moment of the pipe is significantly affected by both burial depth and dislocated forms, while the circumferential bending moment is primarily influenced by burial depth. At a burial depth of 0.5 m, the repair rates of the circumferential bending moments for the spigot and bell are higher than those at a depth of 1.0 m. When the dislocated form is BL, the circumferential bending moment repair rate for the spigot is the highest, approximately 0.52. When the flexural modulus of CIPP increases from 7000 MPa to 9000 MPa, the peak longitudinal bending moments in the midsections of P2 and P3 pipes decrease by about 15 %, while the longitudinal bending moment at the spigot of P2 pipe increases by approximately 22 %. Additionally, when the CIPP liner thickness is increased from 6.0 mm to 18 mm, the peak longitudinal bending moments in the midsections of P2 and P3 pipes decrease by 48 %, and the peak circumferential moments at the spigot and bell decrease by approximately 46 % and 17 %, respectively.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"155 ","pages":"Article 106222"},"PeriodicalIF":6.7,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"P-CSF: Polar coordinate cloth simulation filtering algorithm for multi-type tunnel point clouds","authors":"Zhiyang Zhi ,&nbsp;Bingtao Chang ,&nbsp;Yuan Li ,&nbsp;Zhigang Du ,&nbsp;Yipeng Zhao ,&nbsp;Xiaodong Cui ,&nbsp;Jiahuan Ran ,&nbsp;Aiguang Li ,&nbsp;Wuming Zhang","doi":"10.1016/j.tust.2024.106144","DOIUrl":"10.1016/j.tust.2024.106144","url":null,"abstract":"<div><div>Tunnels are a crucial component of national transportation infrastructure, playing a vital role in social development and urban planning. With the widespread application of 3D laser scanning technology in tunnel engineering, accurately extracting information from vast scanning data and filtering out noise points has become particularly important. To address this challenge, we proposed a Polar coordinate Cloth Simulation Filtering algorithm (P-CSF) to separate lining points from non-lining points in tunnel point cloud data, including tunnels of different shapes and different excavation methods. First, the dual projection method is used to obtain the approximate central axis of the tunnel point cloud. Secondly, a polar coordinate system is established with the roughly determined central axis of the tunnel as the pole, and the simulated cloth is constructed on the outermost part of the section. Subsequently, the gravitational model is used to shrink the cloth particles inward until the distance from the cloth particles to the measured point cloud is less than the specified threshold or the maximum number of iterations is reached. Finally, when the particle motion stops, the points that are in contact with the cloth particles are identified as lining points, while the points that are not in contact are considered as non-lining points. This algorithm was verified in a variety of tunnel scenarios, demonstrating its adaptability and effectiveness. Qualitative analysis indicates that the algorithm can adapt to various scenarios and can adjust the size of simulated cloth details to extract regions of interest as need. Quantitative analysis shows that the overall accuracy of the algorithm exceeded 90% in four typical scenarios, and each scenario obtained a kappa coefficient of nearly 80%, demonstrating its effective extraction capability. In the future, we will continue to optimize the algorithm to cope with more challenging scenarios.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"155 ","pages":"Article 106144"},"PeriodicalIF":6.7,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing the influence of geotechnical uncertainty on existing tunnel settlement caused by new tunneling underneath","authors":"Lihang Hu ,&nbsp;Kiyonobu Kasama ,&nbsp;Gang Wang ,&nbsp;Akihiro Takahashi","doi":"10.1016/j.tust.2024.106189","DOIUrl":"10.1016/j.tust.2024.106189","url":null,"abstract":"<div><div>Inherent soil variability, measurement error, statistical uncertainty, and transformation uncertainty constitute the four main sources of geotechnical uncertainties. This paper presents a systematic probabilistic analysis framework, through a case study, to assess the influence of geotechnical uncertainty on the existing shield tunnel settlement due to new tunneling underneath. Within this framework, various sources of geotechnical uncertainties are quantified using available Cone Penetration Test data (cone tip resistance) in the studied area, and three scenarios (i.e., pessimistic, neutral, and optimistic scenarios) are considered to incorporate different magnitudes of measurement errors. Through a random field-based 3D numerical simulation, the existing tunnel settlement by construction of a new tunnel is evaluated under the three scenarios. The errors in the settlement prediction are quantified using the monitored settlement data in a probabilistic manner with the assistance of Monte Carlo simulations. Two types of errors in predicting the existing tunnel settlement are identified (positive error, which occurs when the predicted settlements exceed the monitored settlement; and negative error, which occurs when the predicted settlements are smaller than the monitored settlement), and a conditional random field-based numerical simulation is performed. The results indicate that the conditional random field-based numerical simulation significantly reduces the positive error at the junction of the two tunnels, with the largest accuracy improvement of 48% for the pessimistic scenario.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"155 ","pages":"Article 106189"},"PeriodicalIF":6.7,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}