Tunnelling and Underground Space Technology最新文献

{"title":"Collision causal discovery and real-time prediction of freeway tunnels: A novel dual-task approach","authors":"Jieling Jin ,&nbsp;Helai Huang ,&nbsp;Ye Li ,&nbsp;Jianjun Dai","doi":"10.1016/j.tust.2024.106216","DOIUrl":"10.1016/j.tust.2024.106216","url":null,"abstract":"<div><div>Although tunnels are critical traffic nodes in freeway networks, academic research addressing their real-time traffic safety is noticeably lacking. This study proposes a novel dual-task approach to analyze causal precursors and predict real-time collision risks in freeway tunnels. Unlike traditional models, which often trade off between predictive accuracy and causal depth, the proposed approach achieves both high causal interpretability and predictive performance. The approach utilizes a structural agnostic model (SAM) to discover causal precursors of freeway tunnel collisions using observational data. The collision causal graph data is then constructed based on the causal relationships identified by SAM. Additionally, the Causal Directed Graph Convolutional Networks (CDGCN) model is developed to capture causal relationships in the graph for real-time collision prediction. Utilizing freeway tunnel collision analysis data collected from the Caltrans Performance Measurement System, the approach performs dual tasks: identifying causal precursors of collisions and predicting future collisions in real time. The SAM results reveal five critical causal precursors influencing the likelihood of collisions. Comparative analyses with existing interpretable machine learning models show similarities between the causal precursors of tunnel collision risk revealed by SAM and the important correlation precursors identified by the comparative models. However, correlation is not the same as causation. When tested against current state-of-the-art real-time collision predictive models, the proposed CDGCN model demonstrates superior accuracy, especially on datasets containing causally relevant precursors, highlighting the potential of this approach for feature selection and risk prediction. This advancement not only provides a practical framework for mitigating collision risks in freeway tunnels but also makes a significant contribution to traffic safety research.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"155 ","pages":"Article 106216"},"PeriodicalIF":6.7,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654141","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":"Numerical analysis and field experiments of a new drainage system with pressure valves for single shield TBM","authors":"Yuan-Chi Zeng ,&nbsp;Lu-Ling Ji ,&nbsp;Yu-Chuan Liu ,&nbsp;S. Feng","doi":"10.1016/j.tust.2024.106175","DOIUrl":"10.1016/j.tust.2024.106175","url":null,"abstract":"<div><div>Single shell segmental lining can withstand a maximum water head of about 50 m. If the water pressure exceeds this value, it is necessary to partially reduce groundwater pressure acting behind the tunnel lining.This paper presents a novel TBM tunnel drainage technology that employs adjustable pressure valves to regulate the volume of incoming water. This method not only reduces the impact of tunnel drainage on the surrounding groundwater environment but also effectively decreases the water pressure behind the lining, lowering the risk of structural damage and enhancing the load-bearing capacity of the lining. This represents an integration of prevention and drainage in the engineering concept of groundwater control.The study commenced with field experiments in the Daxiang Mountain Tunnel of the Fuzhou Intercity Railway, focusing on the effects of different drainage hole spacings and pressure valve settings on tunnel water inflow, pressure behind segmental linings, and strain on the linings’ inner surfaces. A numerical model was subsequently constructed to compare and validate these field monitoring results, which demonstrated a high level of agreement. Finally, a parametric analysis was conducted, and the results indicate:<ul><li><span>(1)</span><span><div>Although increasing the spacing between drainage holes effectively controls groundwater discharge, the resulting higher water gradient near these holes significantly increases bending moments at the foot of the side wall and invert of the lining, thus elevating the risk of structural disorders in the lining.</div></span></li><li><span>(2)</span><span><div>At segmental linings with drainage holes spaced at 3.6 m, the installation of pressure valves set to 400 kPa reduced the drainage volume from 2.18 m³/(D·m) to 1.56 m³/(D·m) compared to the full drainage scenario. This reduction satisfies the groundwater conservation requirements of the Daxiang Mountain area and significantly lowers the risk of structural damage to the lining caused by high water gradients near the drainage holes. Consequently, the load-bearing capacity of the segmental tunnel structure is effectively utilized.</div></span></li></ul>The research outcomes of this paper can offer guidance for the drainage countermeasure design in similar TBM tunnel projects.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"155 ","pages":"Article 106175"},"PeriodicalIF":6.7,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142656082","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":"Innovative cut blasting method for rock excavation at depth based on numerical simulation and field tests","authors":"Junjie Zhao ,&nbsp;Diyuan Li ,&nbsp;P.G. Ranjith ,&nbsp;Xiaoli Su ,&nbsp;Yanliang Li ,&nbsp;XinXin Lyu","doi":"10.1016/j.tust.2024.106211","DOIUrl":"10.1016/j.tust.2024.106211","url":null,"abstract":"<div><div>Drilling and blasting (D&amp;B) has long been an essential technique in rock excavation, particularly in drift mining, where it is frequently employed due to its high efficiency. As mining depths increase, maintaining the efficiency of D&amp;B under high ground stress has become a significant challenge. Cut blasting, the initial stage of D&amp;B in drift mining, plays a critical role in the overall blasting effectiveness. This paper presents an innovative cut blasting method that effectively balances rock fragmentation and cavity excavation. Numerical simulations were performed using LS-DYNA to analyze the cutting performance of the original and the proposed method under various ground stress conditions. The results show that the new method exhibits significant advantages in rock fragmentation, cavity excavation, and energy utilization even under high ground stress conditions. Subsequently, several numerical models were developed to investigate the effect of hole spacing on the cut performance of the proposed method. The findings reveal that although increasing the hole spacing can enlarge the cavity size and provide more free surface space for subsequent blasting, too large spacings lead to a marked decline in cut efficiency. Furthermore, this study explored the impact of blasthole depth on cutting performance of the proposed method. When the hole depth increased from 2.0 m to 2.4 m, the cut efficiency improved significantly, however, further increases in depth do not result in a noticeable gain in cavity volume due to the strong clamping effect, indicating that more explosive would be required for deeper blasting. Based on these findings, recommended values for hole spacing and hole depth are provided. Finally, field tests demonstrate the success and superiority of the proposed method, which can serve as a valuable reference for drift mining at depth.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"155 ","pages":"Article 106211"},"PeriodicalIF":6.7,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142656138","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":"Forced-exhaust-air curtain dust removal measures of tunnel blasting dust based on CFD and orthogonal experiments","authors":"Zheng Chen ,&nbsp;Shulei Zhao ,&nbsp;Shuaishuai Wang ,&nbsp;Yabin Guo ,&nbsp;Bing Sun ,&nbsp;Wengan Chen ,&nbsp;Chun Guo","doi":"10.1016/j.tust.2024.106223","DOIUrl":"10.1016/j.tust.2024.106223","url":null,"abstract":"<div><div>To minimize the dust removal duration associated with tunnel blasting excavation, this study employs on-site measurements and numerical simulations within a railway tunnel to investigate the dynamics of blasting dust during construction. On-site, a dust meter is utilized to monitor the blasting dust in real-time. Utilizing one-dimensional uniform turbulent diffusion theory and numerical simulation, we obtained the total mass of dust present on the surface during tunnel blasting excavation. Building upon the observed diffusion patterns of on-site dust, numerical simulations were conducted to evaluate the efficacy of dust removal in the tunnel using forced, exhaust, and air curtain ventilation methods. Forty-nine sets of orthogonal experiments were established, and, in conjunction with numerical simulation calculations, it was determined that the total amount of blasting dust in the tunnel amounted to 178.1 kg. The orthogonal experimental range analysis revealed that the hierarchy of factors influencing dust removal time was as follows: forced ventilator flow &gt; air curtain flow &gt; exhaust ventilator flow &gt; exhaust ventilator length. From the orthogonal experimental results, the optimal parameters for the forced-exhaust-air curtain dust removal method were identified as follows: the exhaust ventilator length was 4 m, the forced ventilator flow was 26 m³/s, the exhaust ventilator flow was 40 m³/s, and the air curtain flow was 28 m³/s. Under these parameters, the majority of dust in the tunnel was reduced to a safe level within 900 s of initiating blasting ventilation. This investigation into dust removal techniques during tunnel blasting presents a methodology for rapid dust mitigation and serves as a reference for the implementation of on-site dust removal strategies.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"155 ","pages":"Article 106223"},"PeriodicalIF":6.7,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637889","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 granular anisotropic model of underground rockburst considering the effect of radial stresses","authors":"Yuhan Wang ,&nbsp;Guotao Ma ,&nbsp;Mohammad Rezania","doi":"10.1016/j.tust.2024.106202","DOIUrl":"10.1016/j.tust.2024.106202","url":null,"abstract":"<div><div>Rockbursts pose significant concerns in underground construction, and understanding their mechanisms is crucial for enhancing safety in tunneling and underground mining operations. This study innovates an inherently anisotropic rock model using the discrete element method to investigate the effect of local strength degradation on rockburst behavior. Unlike the existing rockburst models in which the anisotropy is either not accounted for or simulated by creating transversely weak planes, the inherent anisotropy is achieved in the contacts between rock grains. Following model calibration, the accuracy of the proposed model is demonstrated by simulating the behavior of rock samples subjected to triaxial rockburst tests. The findings highlight the influence of loading conditions on rockburst behavior in inherently anisotropic rocks and compare micro-crack patterns after rockbursts under different triaxial loading stresses and mesoscale failure types. Notably, this study is the first attempt to combine an inherently anisotropic rock model with rockburst analysis, providing new insights into the mesoscale mechanisms underlying rockburst failure. Notably, it reveals a significant variation in rockburst strength, by about a third, when the anisotropy angle shifts from 0 to 90 degrees. The proposed inherently anisotropic rock model offers an alternative for evaluating the impact of grain-scale strength degradation on rockburst behavior.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"155 ","pages":"Article 106202"},"PeriodicalIF":6.7,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142655999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of interfacial characteristics on dynamic splitting behavior of quasi rock-concrete composite layer: Towards resilient tunnel support against rock burst","authors":"Tong Zhang ,&nbsp;Haiyang Wang ,&nbsp;Meng Chen ,&nbsp;Leilei Niu ,&nbsp;Wancheng Zhu","doi":"10.1016/j.tust.2024.106134","DOIUrl":"10.1016/j.tust.2024.106134","url":null,"abstract":"<div><div>Using shotcrete as lining supports can effectively prevent tunnels from the rock burst of the surrounding rock, while rock-concrete interfaces play key roles in determining the supporting effect. In the present study, both experimental and numerical efforts are made to quantify the effect of joint roughness coefficient (i.e., JRC ranging from 4 to 20) and interface shape (i.e., wave, triangle and ladder-shape) on the dynamic splitting properties of rock-concrete composites. The results show that the dynamic tensile increase factor of the quasi rock-concrete interface increases with the increase of JRC, but the variation of interface shape has a minor effect over the stress rate ranges of 21.95 and 88.14 GPa/s. Specifically, the dynamic tensile strength and dissipated energy of the rock-concrete composites increase by up to 79.25 % and 42.59 %, respectively, with the increase of JRC from 4 to 20, as more concrete hydration products can fill the interface cavities and result in a better bonding effect. In addition, the numerical results reveal that the composite interface exhibits confined tension failure when exposed to dynamic splitting tension, and the enhanced confining effect at higher JRC increases the shear strength of the interface. Overall, the findings can give a basis for optimizing the interfacial characteristics between rock and shotcrete against rock burst.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"155 ","pages":"Article 106134"},"PeriodicalIF":6.7,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637474","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":"Theoretical analysis and experiments on the effect of fire source location on maximum ceiling excess smoke temperature in Z-shaped passage fires with natural ventilation","authors":"Zekun Li ,&nbsp;Miaocheng Weng ,&nbsp;Fang Liu ,&nbsp;Yong Cheng","doi":"10.1016/j.tust.2024.106192","DOIUrl":"10.1016/j.tust.2024.106192","url":null,"abstract":"<div><div>The maximum ceiling excess smoke temperature is a critical parameter for assessing fire safety in Z-shaped passages. These passages are long and narrow spaces formed by two horizontal segments connected by an inclined passage. Smoke movement in such passages significantly differs from traditional confined spaces due to the stack effect and the presence of corners where the horizontal and inclined segments meet. Previous empirical formulas for evaluating the maximum ceiling smoke temperature rise are not applicable to Z-shaped passages. Therefore, this study experimentally explored the impact of fire location, both longitudinally and vertically, on the flame shape and ceiling excess smoke temperature profile of the Z-shaped passage. The results revealed a strong correlation between the stack effect and smoke plume impinging position. By considering the smoke plume deflection angle and fire location, the position of the maximum ceiling smoke temperature rise was determined. Moreover, a new variable, the effective height (<span><math><mrow><msub><mi>h</mi><mi>e</mi></msub></mrow></math></span>) was introduced to replace the passage height. Various heat release rates (HRRs) and fire locations were taken into account in the development of a modified model to determine the maximum ceiling smoke temperatures rise in Z-shaped passages. Experimental data from this work and others were used to verify the model’s accuracy; the results showed greater accuracy in the absence of smoke backflow in the passage.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"155 ","pages":"Article 106192"},"PeriodicalIF":6.7,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637561","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":"Thermal pressure ventilation analysis in a sloping high-temperature tunnel: A case study in China","authors":"Jigang Che ,&nbsp;Angui Li ,&nbsp;Yuanqing Ma ,&nbsp;Jinnan Guo ,&nbsp;Jiaxing Li ,&nbsp;Changqing Yang ,&nbsp;Lunfei Che","doi":"10.1016/j.tust.2024.106183","DOIUrl":"10.1016/j.tust.2024.106183","url":null,"abstract":"<div><div>Heat damage in tunnels is an increasingly prevalent issue, particularly in deeply buried tunnels. Thermal pressure ventilation cannot be ignored in high-temperature inclined tunnels. Implementing appropriate thermal pressure ventilation can lead to substantial energy savings. To achieve this outcome, this study proposes a novel calculation model that integrates analytical solutions for the surrounding rock temperature with discrete solutions for the airflow temperature. The maximum relative prediction error is only 6.9 %. By employing this proposed calculation model, this study analyzes the impact of the ventilation time, environmental temperature, tunnel slope, and tunnel surface roughness on the thermal pressure ventilation dynamics while also analyzing the energy savings potential. This research revealed a negative correlation between ventilation time and environmental temperature with thermal pressure ventilation, while a positive correlation was observed with tunnel slope. Tunnel roughness has a marginal influence on thermal pressure ventilation. For the Nige Tunnel (a high-temperature tunnel with a 2 % slope), the airflow temperature within the tunnel can be effectively lowered to meet the cooling requirements of 28 °C after 407 days of thermal pressure ventilation. The energy-saving analysis demonstrated that thermal pressure ventilation could yield savings of 275 MW·h in the first year, reducing carbon emissions by 23.0 tons. This study provides theoretical guidance for the thermal pressure ventilation of high-temperature inclined tunnels and offers a novel model for thermal pressure ventilation calculations.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"155 ","pages":"Article 106183"},"PeriodicalIF":6.7,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637748","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":"Rayleigh wave-based monitoring of mortar coating and concrete core cracking on prestressed concrete cylinder pipe under external pressure using piezoelectric lead zirconate titanate","authors":"Xu Wang ,&nbsp;Shaowei Hu ,&nbsp;Wenhao Li ,&nbsp;Yuquan Hu","doi":"10.1016/j.tust.2024.106220","DOIUrl":"10.1016/j.tust.2024.106220","url":null,"abstract":"<div><div>Prestressed concrete cylinder pipe (PCCP) is a critical type of pressure pipe widely used in major water conveyance projects worldwide. As essential components of a PCCP, the mortar coating and concrete core are directly linked to its operational safety. This study employed piezoelectric lead zirconate titanate (PZT) devices as transducers to generate excitation vibrations and measure the resulting Rayleigh waves, thereby providing a means to detect cracking in and monitor the health of the mortar coating and concrete core of a prototype 1400 mm inner-diameter PCCP under external pressure. First, a theoretical analysis was conducted to define the propagation laws of Rayleigh waves. Next, a finite element analysis was undertaken to identify the tensile regions of the PCCP mortar coating and concrete core when under external pressure applied along the length of the PCCP and thereby establish the locations for the PZT devices. Experiments were subsequently conducted by incrementally increasing the external pressure load from 0 to 700 kN while monitoring the cracking in the mortar coating and concrete core using sinusoidal excitation signals with frequencies of 5, 10, and 20 kHz. The voltage amplitudes measured at each external pressure load were analysed, confirming the Rayleigh wave propagation laws and revealing that the change in the measured voltage amplitude curve aligned with the experimental observations, thereby validating the proposed measurement method. Finally, the relative percentage deviation of amplitude (RPDA) and relative percentage deviation of energy (RPDE) damage indices were established based on the voltage measurements to further evaluate the damage state of the mortar coating and concrete core. The RPDA measured at an excitation frequency of 20 kHz was best for detecting cracks in the PCCP mortar coating, whereas the RPDA and RPDE measured at excitation frequencies of 20 and 10 kHz, respectively, were best for monitoring concrete core cracking.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"155 ","pages":"Article 106220"},"PeriodicalIF":6.7,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637477","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 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}