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MODERN TUNNELLING TECHNOLOGY
 
2025 Vol.62 Issue.5
Published 2025-10-30
1 Review of Research Progress on Machine Vision-based Joint and Fracture Detection for Mountain Tunnel Faces
CHEN Zhixin1 XIAO Yongzhuo2 CAI Yongchang3 ZHANG Yunbo2
Abstract：Machine vision technology has significant advantages in joint and fracture detection on tunnel faces due to its simplicity and efficiency. This paper reviews the research progress of two mainstream methods: digital image processing and deep learning. First, the specific algorithms applied in each stage of the “image preprocessing-joint and fracture segmentation-skeleton extraction” workflow using digital image processing methods are elaborated, and their limitations in complex tunnel environments are summarized. Second, the application scenarios of commonly used classification and semantic segmentation models in deep learning-based methods are analyzed. Then, the calculation method of real joint size on tunnel faces is discussed, together with the computation of joint occurrence parameters, trace length, spacing, and grouping. Finally, future development directions are proposed, including the adoption of semantic segmentation models as the core framework, integration of skeletonization techniques from digital image processing, enhancement of 3D reconstruction theory, and improvement of the efficiency and accuracy of 3D joint feature extraction, so as to better support tunnel construction.
2025 Vol. 62 (5): 1-12 [Abstract] ( 26 ) [HTML 1KB] [ PDF 3927KB] ( 111 )
13 ime-dependent Evolution and Transfer Mechanisms of Loads in Composite Lining Systems of High In-situ Stress Soft Rock Tunnels
ZHAN Hongxiang CHEN Ziquan WANG Bo ZHOU Zihan
To investigate the temporal evolution of surrounding rock pressure and its transfer pathways within composite lining systems in high in-situ stress soft rock tunnels, a theoretical analytical framework is proposed that incorporates surrounding rock damage evolution and performance degradation of support structures. Based on the Maoxian Tunnel of the Chengdu-Lanzhou Railway, field monitoring data are integrated to analyze the load evolution under single-layer and double-layer initial support configurations. The coupled mechanisms between rock mass rheological damage and support deterioration are revealed, and the time-dependent load evolution from the surrounding rock to support components is quantitatively characterized. The results show that the combined effects of rock mass rheological damage and time-dependent degradation of support elements drive the gradual transfer of extrusion loads from the initial support to the secondary lining, resulting in an increasing load-sharing ratio of the secondary lining. Theoretical calculations indicate that the load-sharing ratios of the secondary lining reach 69% and 49% for the single-layer and double-layer initial support schemes, respectively, demonstrating the effectiveness of multi-layer initial support in mitigating load evolution to the secondary lining. Enhancing the stiffness of the primary support, reducing the stiffness of the secondary lining, and introducing a reasonable lag in secondary lining installation can effectively reduce the load carried by the secondary lining, thereby suppressing long-term load evolution within composite lining systems of deep-buried soft rock tunnels.
2025 Vol. 62 (5): 13-24 [Abstract] ( 21 ) [HTML 1KB] [ PDF 6770KB] ( 114 )
25 Seismic Resilience Analysis of Deep-buried Tunnels Based on Fragility Curves
HUANG Zhongkai1 WU Yiqun1 ZHANG Dongmei1 WANG Qingzhi2
Seismic performance of deep-buried tunnels directly affects the resilience of cities and their post-disaster recovery capability. Traditional seismic analyses mainly focus on structural strength failure, whereas resilience-based evaluation using fragility curves enables quantitative assessment of the damage probability and functional loss of tunnels under different seismic intensities, thereby supporting resilience-oriented design throughout the tunnel life cycle. In this study, a deep-buried shield tunnel in soft ground is adopted as the research object. The concrete damage constitutive model is used to represent the tunnel lining, and a two-dimensional dynamic numerical model considering soil-structure interaction is established using finite element software, incorporating different seismic characteristics. Through incremental dynamic analysis, the dynamic response of tunnel internal forces and deformations under varying seismic intensities is investigated. Based on the peak ground acceleration as the intensity measure and deformation ratio and bending moment ratio as engineering demand parameters, the seismic probabilistic demand model of the deep-buried tunnel is constructed. Subsequently, fragility curves corresponding to different seismic intensities are developed to obtain the failure probabilities under various damage states. Furthermore, by incorporating the functional recovery function of the tunnel, the seismic resilience index is quantified for different seismic hazard levels, enabling the seismic resilience assessment of deep-buried tunnels. Results indicate that the resilience index decreases with increasing seismic intensity; however, the deep-buried tunnel can still maintain a Level II or above resilience rating, demonstrating favorable seismic resilience.
2025 Vol. 62 (5): 25-35 [Abstract] ( 21 ) [HTML 1KB] [ PDF 5323KB] ( 115 )
36 Calculation Method for the Ultimate Face Support Pressure of Shield Tunnels in Highly Permeable Sandy Soils
LONG Haiping1 LU Qingbi2 KUANG Yan2 ZHU Zhiliang2 XIONG Guangyi2 WU Shiliu2 HU Ziwei3
To address the face stability issue of shield tunnels constructed in highly permeable sandy soils, a calculation method for the ultimate support pressure at the tunnel face is developed based on the upper bound theorem of limit analysis. A three-dimensional rotational failure mechanism is constructed using a spatial discretization technique. By comparing the proposed method with existing analytical solutions and further validating it through numerical modeling, a sensitivity analysis of key parameters is conducted. The results indicate that: (1) the discrepancy between the proposed method and the existing analytical solutions is within 7%, while achieving significantly higher computational efficiency; (2) although the difference from numerical simulation results is approximately 20%, the proposed method provides a reference for effectively controlling seepage at the tunnel face; (3) groundwater level exerts the most pronounced influence on the ultimate support pressure, followed by internal friction angle, while soil unit weight has the least effect. A case study from an actual metro shield tunnel project further verifies the reliability of the proposed calculation method.
2025 Vol. 62 (5): 36- [Abstract] ( 24 ) [HTML 1KB] [ PDF 3267KB] ( 58 )
43 Study on Non-limit Active Earth Pressure Distribution of Deep Large Circular Excavations Considering Groundwater and Spatial Soil Arching Effects
LIANG Yu1,2,3 FAN Xiaofeng3 HUANG Linchong2,3 ZHOU Zhonghai4 MENG Tao5
With the increasing application of deep and large circular excavations, developing an earth pressure evaluation method that comprehensively accounts for complex influencing factors is of significant engineering value for enhancing design accuracy and scientific reliability. In this study, a non-limit active earth pressure calculation method for circular excavations is proposed, which incorporates groundwater effects, spatial arching effects, and wall displacement patterns. The applicability and effectiveness of the method are validated through an engineering case study. Furthermore, the influences of soil parameters, wall displacement patterns, surface surcharge, and groundwater level on earth pressure distribution are investigated. The results show that the earth pressure in circular excavations first increases and then decreases with depth, and due to spatial arching effects, it is significantly lower than the traditional Rankine earth pressure estimation. The earth pressure is negatively correlated with soil cohesion and internal friction angle. Surface surcharge generates additional earth pressure on the upper portion of the wall, which decreases with depth. A lower groundwater level, larger wall displacement magnitude, and wider displacement zone result in a more significant reduction in active earth pressure.
2025 Vol. 62 (5): 43- [Abstract] ( 18 ) [HTML 1KB] [ PDF 3525KB] ( 80 )
52 Stability Analysis of Slurry Trench Excavation in Weak Soil Layers Using an Adaptive Upper-bound Finite Element Method#br#
ZHANG Kai1 CAI Haibing1 SUN Rui1 WANG Bing1,2 PENG Jianyong2
To address the stability problem of slurry trench excavation for diaphragm walls in heterogeneous composite soil layers, a stability analysis approach based on the adaptive upper-bound finite element method is adopted. An adaptive numerical model incorporating second-order cone programming and high-order finite elements is developed, and a system of dimensionless parameters is established to systematically investigate the influence of weak soil layer distribution on the critical slurry coefficient C and the evolution of critical failure surfaces. The results indicate that in an upper-soft-lower-hard stratigraphy, C exhibits a nonlinear increase with the thickness ratio k of the weak layer, where the failure mode combines localized shear and toe-type failure characteristics, while in an upper-hard-lower-soft stratigraphy, the failure surface becomes significantly constricted. The slope of the critical failure surface is positively correlated with the internal friction angle of the corresponding soil layer, and the predicted failure morphology shows strong agreement with previously published results. This study provides an efficient and reliable analytical method for evaluating trench stability in weak soil environments.
2025 Vol. 62 (5): 52- [Abstract] ( 22 ) [HTML 1KB] [ PDF 10336KB] ( 85 )
65 Stability Assessment and Reinforcement Study of the Tunnel Portal Slope in Water-bearing Miscellaneous Fill during Tunnel Construction
To investigate the influence of water-bearing miscellaneous fill layers on the stability of tunnel portal slopes after heavy rainfall, the landslide event at the Tangshan Road Tunnel portal was selected as a case study. First, a dedicated geological investigation was conducted to characterize the soil layers within the landslide zone and to determine the extent and depth of the water-enriched area on the portal slope. Then, the stability of the original reinforcement scheme was evaluated using the strength reduction method. Following the principle of water-first slope stabilization, an improved reinforcement scheme combining dewatering and pumping, two-fluid grouting with small pipes, and gentle slope forming was proposed. Subsequently, the shear strength parameters of the grouted soil were determined through laboratory testing and the yield function of the two-fluid composite material. The safety stability coefficients of the portal slope under different groundwater levels were then compared and analyzed. The results show that the fill layer in the landslide area exhibits strong heterogeneity, low bearing capacity, and high permeability. Under heavy rainfall conditions, the safety factor of the original reinforcement scheme fell below the design requirements, consistent with the observed field collapse. When the groundwater level was reduced to 74.5 m under heavy rainfall conditions, the proposed scheme reduced the maximum displacement and shear stress of the portal slope by 64.2% and 20.3%, respectively, compared to the original scheme (with groundwater level at 88 m), while the safety factor increased by 49.5%. Field monitoring confirmed that, after applying the improved reinforcement measures, the surface settlement of the portal slope remained within the specified design limits.
2025 Vol. 62 (5): 65- [Abstract] ( 30 ) [HTML 1KB] [ PDF 10402KB] ( 129 )
78 Comparative Analysis of Disc Cutter Wear in Straight and Curved Sections during TBM Excavation of the Beishan Spiral Ramp#br#
XIANG Yu1 GONG Qiuming1 XIE Xingfei1 HUANG Liu1 WANG Ju2,3 MA Hongsu2,3
In order to analyze the wear characteristics of disc cutters during TBM construction in spiral tunnels, the cutter replacement and wear data obtained from the TBM excavation of the Beishan spiral ramp were collected, and the surrounding rock data along the ramp were obtained. A comparative analysis was conducted on the number of cutter replacements, cumulative cutter wear, and cutter wear rate under similar surrounding rock conditions in straight and curved sections. The results show that the cutter consumption per unit advance in curved sections is significantly higher than that in straight sections, especially the increase in abnormal failure proportion of center cutters and the increase in wear rate of edge cutters. Combined with the wear mechanism of cutters under the two alignment conditions, it is found that the cutters are subjected to unbalanced forces in curved sections, and the lateral forces on edge cutters increase significantly, resulting in an increase in their wear rate.
2025 Vol. 62 (5): 78- [Abstract] ( 25 ) [HTML 1KB] [ PDF 6571KB] ( 98 )
88
Rapid Improvement of High-altitude Sickness among Tunnel Construction Workers through a Gradual Intermittent Hypobaric Hypoxic Acclimatization Technique
Rapid Improvement of High-altitude Sickness among Tunnel Construction Workers through a Gradual Intermittent Hypobaric Hypoxic Acclimatization Technique[J]. MODERN TUNNELLING TECHNOLOGY, 2025,62(5): 88->')" href="#"> QIU Jiewen1,2 HUANG Cheng3 SU Ke4 ZHAO Shulei1,2 GUO Chun1,2
To reduce the risk of high-altitude sickness in tunnel construction workers operating on plateaus, a gradual and intermittent hypobaric hypoxic acclimatization technique was proposed. In a stratified randomized controlled trial, eight healthy lowland residents were randomly assigned to either a control group or a hypoxic exposure group. A hypobaric hypoxic chamber was used to simulate a gradient altitude environment ranging from 2,500 m to 5,000 m. A 7-day resting exposure protocol was applied with 3 hours of daily training under a stepwise ascending altitude scheme. The results show that this acclimatization approach significantly reduces the incidence rate and severity of acute mountain sickness (AMS) based on Lake Louise Score (LLS). Resting blood oxygen saturation increased by 6.98%, heart rate decreased by 17.24%, and the compensatory elevation in tidal volume (VT) recovered close to the baseline level at sea level. This short-term, 7-day acclimatization protocol overcomes the prolonged duration required by traditional staged acclimatization strategies and effectively satisfies acclimatization demands for high-altitude tunnel construction.
2025 Vol. 62 (5): 88- [Abstract] ( 20 ) [HTML 1KB] [ PDF 4673KB] ( 137 )
97 Multi-objective Intelligent Optimization Framework for Construction Procedures of Large Cross-section Karst Tunnels Excavated Beneath Airports Using Roadheaders
WANG Jie1,2 DING Wenyun3 LUO Wei1,2 YANG Jinjing3 ZHANG Jinrong4 XUE Yadong1,2

For large cross-section tunnels constructed with roadheaders, the coordination of multiple construction procedures often relies heavily on operational experience, leading to low efficiency and difficulties in settlement control. To address these challenges, and based on the Changshui Airport Tunnel project along the Chongqing-Kunming High-Speed Railway, this study proposes an intelligent optimization framework that integrates excavation efficiency prediction, settlement early warning, and multi-procedure parameter optimization. First, multi-source monitoring data were temporally and spatially aligned to develop a LightGBM-based prediction model enhanced with Bayesian optimization for excavation efficiency, and a Multi-LSTM vault settlement prediction model incorporating geological conditions, construction procedure features, and dynamic face advancement. The results show that the two models achieve coefficients of determination of 0.77 and 0.94, respectively, accurately mapping relationships among construction parameters and geotechnical properties. Furthermore, the NSGA-Ⅱ multi-objective optimization algorithm was adopted to conduct coordinated optimization of key construction parameters, including cyclic advance length, support duration, and support strength. The results indicate that under typical karst geological conditions, the optimized strategies improve tunneling efficiency by an average of 34.6% while reducing settlement by an average of 23.1%.
2025 Vol. 62 (5): 97- [Abstract] ( 21 ) [HTML 1KB] [ PDF 9216KB] ( 75 )
109 Intelligent Recognition and Quantification of Rock Fragmentation #br# at the Tunnel Face Using UAV-based Methods for Roadheader Excavation
HUNAG Feipeng1,2 GUO Yongfa3 DING Wenyun3 SHI Yu4 XUE Yadong1,2 ZHENG Zhaohui1,2
To mitigate the interference of construction dust on tunnel face observation during roadheader excavation and eliminate the subjectivity associated with manual rock mass assessment, an intelligent recognition method is proposed for quantifying rock fragmentation at the tunnel face by integrating unmanned aerial vehicle (UAV) autonomous inspection with computer vision techniques. First, the Fast-Planner algorithm is employed to achieve UAV autonomous obstacle avoidance and path planning, enabling continuous acquisition of 412 high-resolution RGB images from 100 excavation cycles at a high-speed railway tunnel construction site in Yunnan Province. Then, a U-Net++ network is used for feature extraction, and kernel density estimation is applied to fit the probability distribution of the fragmentation ratio k, showing that the main density peak is located near 0.11. Finally, a cuttability evaluation table for roadheader excavation is developed based on the value of k. The results show that the proposed method achieves an 83.2% accuracy in extracting rock mass features, significantly outperforming traditional manual assessment and providing a feasible solution for safe, efficient, and intelligent tunnel construction evaluation.
2025 Vol. 62 (5): 109- [Abstract] ( 24 ) [HTML 1KB] [ PDF 4337KB] ( 84 )
116 BM Advance Rate Advance and Interpretability Analysis Using the #br# NRBO-XGBoost Method
ZHAO Neng1 TANG Bin1, 2 CHENG Hua1 YAO Zhishu1 LIU Xiaohu1 HOU Junling3
Advance rate is a key indicator reflecting the interaction between tunnel boring machines (TBMs) and surrounding rock, and its reliable prediction is essential for TBM performance optimization. A hybrid model combining the Newton-Raphson-Based Optimization (NRBO) algorithm with the Extreme Gradient Boosting method (XGBoost), referred to as NRBO-XGBoost, is proposed to predict TBM advance rate. A total of 350 sample data from a TBM construction project in the west wing gas control roadway of a coal mine in Huainan, Anhui Province, were collected to train and validate the model. The capability and applicability of the model were evaluated using the coefficient of determination (R²), root mean square error (RMSE), and mean absolute error (MAE). The results demonstrate that the NRBO algorithm effectively optimizes the hyperparameters of XGBoost, enabling the NRBO-XGBoost model to achieve high stability and generalization performance. In the testing phase, the R², RMSE, and MAE values of the NRBO-XGBoost model reached 0.981, 0.792, and 0.512, respectively, outperforming the standalone XGBoost model. Additionally, stable prediction results were also obtained for new data. Based on the SHapley Additive exPlanations (SHAP) method, the importance of input parameters was analyzed from both global and individual perspectives, showing that the top six influential variables were penetration index, cutterhead rotational speed, rock abrasion value, thrust, torque, and compressive strength of the rock.
2025 Vol. 62 (5): 116- [Abstract] ( 26 ) [HTML 1KB] [ PDF 4674KB] ( 81 )
125 Study on Influencing Factors and Evaluation Method of Mud Quality in #br# Highly Permeable Strata Based on a Transformer Architecture
CHENG Wei1 LIU Peizhong1 Liu Wei1 Ming Yang2,3 Wu Kexiong2,3
To address the mud film quality issues in highly permeable sand-gravel strata, mud penetration simulation tests were conducted under varying formation and mud parameter conditions. A high-precision prediction model was developed based on a Transformer deep learning architecture, and the key factors affecting mud film quality were further analyzed. The results indicate that filtrate volume, mud cake type, and mud cake quality differ markedly among muds in different formations, suggesting that mud formulation should be tailored to formation characteristics. As the formation permeability coefficient increases, the effective particle size of the mud (i.e., particle gradation) becomes the dominant factor influencing filtrate volume, whereas the effect of mud viscosity gradually weakens and eventually becomes negligible. The relationship graphs among filtrate volume, formation permeability coefficient, and mud parameters derived from the model can optimize mud parameter design and provide scientific guidance for mud preparation. Moreover, a mud film quality evaluation method based on the concept of an ideal mud cake is proposed. By introducing the filtrate volume ratio, mud film quality can be effectively assessed, with a reasonable range of 0.4-0.6.
2025 Vol. 62 (5): 125- [Abstract] ( 30 ) [HTML 1KB] [ PDF 7044KB] ( 76 )
135 Study on Mechanical Performance of Large-span and Small-clearance #br# Cut-and-Cover Tunnel with Composite Joint Structure during #br# Construction Stage
XU Zhanglong LIN Zhi GUO Xiande ZHANG Zhiming GOU Xiaoying LIU Lili DING Ming
Taking the Chongqing Xinsen Avenue cut-and-cover large-span prefabricated assembled tunnel project as the research background, a new type of assembled tunnel structure based on composite joints is proposed. A strata-structure numerical model is established, considering the influence of contact relationship, backfill hardening process, and compaction construction process. The mechanical behavior of a three-piece composite joint structure at the vault, a two-piece cast-in-place structure at the vault, and a traditional integral cast-in-place structure during the whole backfilling construction process is simulated and analyzed. The accuracy of the model is verified through comparison with field measurement data. The results show that during the backfilling stage, the composite joint structure exhibits superior deformation control capability, and the distribution of axial force and bending moment is more uniform. Compared with the two-piece structure and the integral cast-in-place structure, the vault settlement of the composite joint structure is reduced by 33% and 46%, respectively, and the peak bending moment is reduced by 82% and 40%, respectively. By optimizing stress distribution and enhancing overall stiffness, the composite joint effectively improves structural safety.
2025 Vol. 62 (5): 135- [Abstract] ( 22 ) [HTML 1KB] [ PDF 8246KB] ( 91 )
146 Analysis of the Jamming Influence Mechanisms of Double-shield TBM #br# Operations in Jointed Rock Masses
WANG Yue1 WANG Qingjiang1,2 WU Fei2 JIN Guangshuo3
Double-shield tunnel boring machines (TBMs) are prone to jamming incidents when tunneling through jointed rock masses. To effectively mitigate such risks, it is therefore essential to investigate the mechanisms underlying TBM jamming in jointed geological conditions. In this study, a numerical model is established using the discrete-element software 3DEC. Combined with an orthogonal experimental design, the influences of geological conditions, joint characteristics, and anti-jamming measures on the contact pressure between the surrounding rock and TBM are comprehensively evaluated. The results indicate that the burial depth and over-excavation clearance exert extremely significant effects on the contact pressure. The angle between the joint strike and tunnel axis, as well as joint spacing, exhibit very significant influences. The soft filling length and lateral pressure coefficient have significant impacts, while other parameters show negligible effects.
2025 Vol. 62 (5): 146- [Abstract] ( 24 ) [HTML 1KB] [ PDF 3119KB] ( 79 )
154 Mechanical Performance of Longitudinal Segmental Joints in Shield Tunnels Reinforced with Corrugated Plates
MA Chang1,2 GUO Yingjie1,2,3 DING Wenqi1,2 ZHANG Qingzhao1,2

To clarify the strengthening mechanism of corrugated plates on the mechanical behavior of longitudinal segmental joints in shield tunnels, a refined three-dimensional finite element model incorporating corrugated plate joints was established. The numerical model was validated using full-scale test results. The enhancement effects of corrugated plate reinforcement on the bending stiffness and ultimate bearing capacity of segmental joints were investigated. Moreover, the influence of axial force, reinforcement timing, and corrugated plate joint configuration on the mechanical performance of reinforced joints was examined. The results indicate that the proposed numerical model can accurately simulate the nonlinear mechanical behavior of corrugated-plate-reinforced longitudinal joints subjected to combined compression and bending, demonstrating good agreement with experimental observations. Under negative bending moments, corrugated plate reinforcement increases the ultimate bending capacity by 29.4%, while the bending stiffness in the elastic-plastic stage and at ultimate failure is enhanced by 101.8% and 40.5%, respectively. When a double-row bolt connection is adopted, the ultimate bending capacity is only 2.6% lower than that of fully welded corrugated plates, and is 31.1% higher than that of a single-row bolt connection. It is therefore recommended to prioritize the double-row bolt configuration to prevent failure at the corrugated plate-segment interface.
2025 Vol. 62 (5): 154- [Abstract] ( 27 ) [HTML 1KB] [ PDF 4094KB] ( 91 )
161 Study on the Evolution of the Temperature Field and Dynamic Regulation of Ventilation Airflow during the Construction of Submarine Shield Tunnels
LIU Sijin1 MA Yuyang1 Zhou Xiaohan2 Yu Xingqiao1 Xu Liang2 Wang Yan2
To reveal the evolution law of the temperature field inside submarine tunnels under the coupled effects of external environmental temperature variations and construction cycles, and to optimize ventilation parameters, both field monitoring and numerical simulations were conducted. First, the non-steady-state evolution characteristics of the tunnel temperature field were analyzed based on field measurements. Then, a three-dimensional ventilation-heat transfer numerical model considering cutterhead frictional heat generation was established to comparatively investigate the dynamic thermal responses of the tunnel during excavation and shutdown conditions. Adaptive optimization of ventilation parameters was subsequently performed for representative construction stages. The results show that: (1) The temperature distribution along the tunnel is not affected by construction stoppages. When the tunnel advances to 6,932 m and the ambient temperature is 24.3 °C, the temperature from the first segment car to the 1,300th ring exhibits a “rapid drop (cutterhead-ring 3,350) followed by a gradual decline (ring 3,350-ring 1,300)” pattern, and becomes stable beyond 3 km behind the tunnel face. (2) During excavation, the airflow around the first segment car forms multiple vortices, leading to heat retention and a relatively higher temperature; after stoppage, the temperature initially rises slowly and then gradually decreases. (3) External temperature fluctuations exert significant influence on the tunnel′s internal temperature, and ventilation airflow should be dynamically adjusted according to different construction phases.
2025 Vol. 62 (5): 161- [Abstract] ( 25 ) [HTML 1KB] [ PDF 6898KB] ( 121 )
172 Study on Stress Response and Deformation Mechanism of Pipe Sections under Complex Deflection Modes
ZHANG Yongjie1 ZHANG Xinyu1 CHEN Jianhua1,2 OU Xuefeng1 LUO Zhimin1 WU Hanghui1
To investigate the influence of deflection on the mechanical behavior of pipe sections, large-scale indoor model tests and numerical simulations were conducted. The stress distribution characteristics between pipe sections under three types of complex contact conditions were systematically analyzed, with a focus on the influence of jacking load levels, deflection modes, and deflection angles on pipe deformation and stress development. The results indicate that under unidirectional deflection, the pipe exhibits a horizontally biased compression state, and the axial stress increases significantly with increasing deflection angle and load, with the strain distribution showing a “horizontal cone” pattern. An increase in deflection angle results in local extrusion deformation, causing abrupt stress variation. Under diagonal deflection, opposite stress concentrations occur at the deflection cross-sections (1-1 and 2-2), and the overall stress level is lower than that under unidirectional deflection. The axial force transfer at the joint reveals that, with increasing load, the contact pressure at the top of the joint increases and the deformation strain shows nonlinear growth. Moreover, a larger deflection angle changes the contact condition at the joint, making the jacking force transfer path more pronounced. In addition, under combined deflection modes, axial stress varies linearly with deflection angle, while reduced contact area significantly affects the load-transfer characteristics.
2025 Vol. 62 (5): 172- [Abstract] ( 26 ) [HTML 1KB] [ PDF 8443KB] ( 142 )
183 Research on the Mechanism and Prevention Measures of Water Inrush in Weakly Cemented and Water-rich Red-bed Tunnels#br#
WEI Jia1,2 ZHU Xingyu1,2 ZHANG Zhiqiang1,2 GE Hong1,2 ZHOU Zelin3
Affected by both weakly stratified rock structures and groundwater conditions, water inrush disasters are prone to occur in weakly cemented and water-rich red-bed tunnels. Relying on the Longgang Tunnel of the Kaiyun Expressway, field tests and laboratory experiments are carried out to reveal the disaster-causing structural characteristics of water-bearing sections in the tunnel area, and the failure mechanical mechanism of weakly cemented red-bed rock mass. A three-dimensional discrete element Bonded Block Model (BBM)-fracture flow coupling model is established to analyze the evolution process of water inrush disaster in tunnels, investigate the influence of weakly cemented rock layer thickness and dip angle on the disaster, and evaluate the effectiveness of engineering control measures. The results show that: (1) Permeability failure tests indicate that seepage mainly occurs in rock fractures. (2) Water inrush is accompanied by fracture propagation and an increase in seepage rate in weakly cemented red-bed rock mass, and their interaction leads to the instability of surrounding rock at the tunnel face and a sharp drop in water pressure. (3) Rock layer thickness has a significant influence on surrounding rock instability and water inrush, while the influence of structural plane dip angle is relatively small. Under the condition of 0.3 m layer thickness, when excavation enters 3 m into the fractured zone, the water inflow reaches 954.2 m³/h, and the disturbance failure zone and seepage failure zone in front of the tunnel face reach 5.91 m and 3.14 m, respectively. (4) Drainage and pressure relief can effectively reduce water pressure at the tunnel face and inhibit seepage failure, and grouting reinforcement can improve rock mass strength and block seepage channels. The combined “drainage-grouting” control measure shows significant mitigation effectiveness.
2025 Vol. 62 (5): 183- [Abstract] ( 23 ) [HTML 1KB] [ PDF 18305KB] ( 77 )
198 Investigation on Grouting Diffusion for Seepage Control in Water-rich Sandy Strata of Deep Excavations
LI Chuitian1 ZOU Bo2 LU Qingbi3 PENG Yang3 KUANG Yan3 XIONG Guangyi3 XIAO Fenglong4
To address grouting performance in water-rich sandy strata, a visualized grouting model test system and a discrete element numerical model for slurry diffusion were established. Comparative investigations were conducted to clarify the influence of grouting materials, grouting pressure, and groundwater level on the diffusion behavior of slurry, and to evaluate the water-blocking effectiveness of various grouting materials under seepage conditions. The results show that, under identical seepage conditions, the diffusion extent of the three grouting materials ranks as: two-component slurry > hydrophilic polyurethane > epoxy resin. The diffusion performance is positively correlated with slurry viscosity and fluidity. Grouting pressure is the primary controlling factor for slurry penetration depth, while groundwater level exhibits a negative correlation with grouting diffusion effectiveness. With increasing grouting pressure, the slurry diffusion radius exhibits a decelerating growth trend, with a significant reduction in growth rate when the pressure exceeds 0.3 MPa. Meanwhile, sand compaction increases concurrently, but weakens significantly along the radial direction.
2025 Vol. 62 (5): 198- [Abstract] ( 20 ) [HTML 1KB] [ PDF 4434KB] ( 88 )
206 Study on the Abrasivity and Temperature Influence Mechanism of Frozen Soft Rock in the Cretaceous-Jurassic Strata
RONG Chuanxin1 YANG Fan1,2 WANG Bin1 SUN Shicheng1
To investigate the abrasivity of frozen soft rock in the Cretaceous-Jurassic strata and its temperature-dependent mechanism, soft rock from the No. 2 return air shaft of the Subuerga Mine in Inner Mongolia was selected as the research object. Based on an improved low-temperature Cerchar Abrasive Index (CAI) test system, abrasivity tests were conducted on siltstone, fine sandstone, and mudstone under different subzero temperatures (−5 °C, −10 °C, −15 °C, −20 °C, −25 °C). Meanwhile, an optical microscope and a laser confocal microscope were utilized to scan the morphology of the worn steel needle tip and the three-dimensional morphology of the scratch grooves on the rock surface. The abrasive characteristics of frozen soft rocks were systematically analyzed. The results show that CAI exhibits a negative linear correlation with temperature but a positive linear correlation with uniaxial compressive strength. The variation rate of rock abrasivity is jointly governed by the coupled effects of mineral composition, internal structure, and mechanical behavior. Significant differences in needle wear morphology were observed among different rock types, with wear mechanisms categorized as coarse-particle wear, fine-particle wear, and inclined wear. Essentially, the rock abrasivity test represents a process of extrusion and shear failure of rock induced by the steel needle.
2025 Vol. 62 (5): 206- [Abstract] ( 20 ) [HTML 1KB] [ PDF 9516KB] ( 73 )
216 Experimental Study on the Evolution Mechanism of Unfrozen Water #br# Distribution in Water-rich Weakly Cemented Sandstone
ZHANG Zihao1, 3 WANG Bin1, 2, 3, 4 HUANG Jinkun4 RONG Chuanxin1, 3 LIANG Xiuling1, 3
With the westward shift of coal resource exploitation in China, water-rich and weakly cemented sandstone strata have emerged as a major geotechnical challenge in deep coal mining. However, systematic investigations remain scarce regarding the dynamic response mechanisms of unfrozen water in such low-strength, water-sensitive rock under deep multi-field coupling conditions. In this study, sandstone samples collected from the Suboergai mining area in the Ordos Basin were examined to elucidate pore structure evolution, unfrozen water distribution behavior, and nuclear magnetic imaging characteristics. The results indicate that: (1) During the freezing stage, pore water in all three sandstone types solidifies sequentially as “free water → capillary water → adsorption water”, whereas thawing follows the reverse order “adsorption water → capillary water → free water”. (2) Nuclear magnetic resonance imaging reveals that pore water in fine-grained sandstone is mainly enriched in the lower-T? region, with no supercooling effect observed, and the final unfrozen water content reaches 3.08%. Pore water in fine-gravel sandstone and siltstone exhibits a central-dominant and a relatively uniform distribution, respectively, both experiencing supercooling (freezing temperature −1.5 to −2 °C), with final unfrozen water contents of 6.69% and 3.37%. The proportion of micro-pores inside the rock is negatively correlated with the freezing point temperature. (3) Freeze-thaw cycling promotes an increase in small- and medium-sized pore throats while reducing large pore throats, thereby accelerating structural deterioration of the rock mass.
2025 Vol. 62 (5): 216- [Abstract] ( 15 ) [HTML 1KB] [ PDF 5691KB] ( 84 )
225 Experimental Study on the Development Law of Suffusion in Shield Tunnels within Gap-graded Sandy Strata
CHEN Sirui1 ZHANG Dongmei1, 2 XIE Xiaochuang1 ZHANG Xueliang1
For shield tunnels constructed in gap-graded sandy soils are subject to a significant risk of segment joint leakage during operation. Seepage flow may transport fine soil particles away from the coarse-grained skeleton into the tunnel interior, resulting in suffusion. However, the developmental mechanism of suffusion and its influence on ground stability and tunnel structure remain unclear. In this study, a self-developed visualized test system for tunnel suffusion was employed, coupled with dynamic monitoring of water and soil pressures and quantitative measurement of soil loss, to investigate the characteristics and impacts of the entire suffusion process. A gap-graded sand with 35% fines content was selected. The leakage hole diameter was set to less than twice the coarse particle size, and a constant hydraulic head of 20 kPa was applied to induce suffusion. Test results show that the soil loss rate reaches a peak at the initial stage and gradually decreases until particle migration ceases, while the seepage discharge continuously increases. The suffusion initiates near the leakage hole and progressively expands to form a U-shaped erosion zone, accompanied by stratum deformation and surface settlement. After suffusion onset, circumferential loads around the tunnel decrease, with approximately 70% reduction observed above the tunnel due to severe fines loss, which may lead to tunnel uplift and lateral convergence deformations.
2025 Vol. 62 (5): 225- [Abstract] ( 21 ) [HTML 1KB] [ PDF 3865KB] ( 72 )
231 Experimental Study on the Blast-resistance Performance of Shield Tunnels Subjected to Internal Explosion Loads
ZHOU Long1 LU Hao2 XIA Mengtao3 ZHANG Wenchao4 SHI Guoqing4 CHEN Danhe 5
To investigate the blast-resistance performance of shield tunnels subjected to internal explosive loads, a field blast test was conducted on a scaled shield tunnel model. The damage patterns and dynamic responses under internal explosion loads were analyzed and compared with the results of similar experimental studies reported in the literature. The results show that the dynamic response of the segmental lining under internal explosions is significantly influenced by structural configuration and overburden conditions. Under central explosion scenarios, the vibration response at the vault is much stronger than that at the springline. Under close-in blast loads, damage in the near-field region mainly includes segmental joint dislocation, concrete spalling at circumferential joints, and concrete crushing at longitudinal joints; while in the far-field region, circumferential and longitudinal joint dislocation and tensile cracking of concrete are dominant. Under contact explosion loads, local blast craters and radial cracking are the main failure modes, and the presence or absence of segmental joints has a significant effect on the crater size and shape. Comparative analysis with published internal blast test results on shield tunnels indicates that the failure mode is strongly correlated with the blast charge weight: with increasing charge weight, the dominant failure mode shifts from tensile cracking along longitudinal joints to shear failure along circumferential joints, and further increase in charge weight may trigger a risk of collapse.
2025 Vol. 62 (5): 231- [Abstract] ( 20 ) [HTML 1KB] [ PDF 10763KB] ( 69 )
243 Experimental Study on Soil Disturbance Effects Induced by Pipe Jacking in Soft and Water-rich Strata
MAO Yufei1 XIAO Zhengwei2 GUO Zenghui2 FU Lin3 XIE Yipeng4
To investigate the disturbance behavior and parameter design of pipe jacking in soft and water-rich strata, a series of physical model tests was conducted using a self-developed testing system. The variations in jacking force, soil pressure, and surface vertical displacement during the jacking process were analyzed. The results show that the evolution of jacking force consists of three stages: the initial stage, the transition stage, and the stable stage. Its variation rate is jointly influenced by jacking velocity and grouting pressure. A higher jacking velocity helps mitigate the decay of jacking force, whereas a moderate increase in grouting pressure can reduce the force magnitude and suppress fluctuations. However, under high jacking velocity, the mitigation of soil disturbance becomes limited. Soil pressure exhibits pronounced fluctuations, with the peak position shifting forward along the jacking direction as the jacking velocity increases. A higher grouting pressure can lower the peak magnitude and reduce the distance to its occurrence. Surface vertical displacement is primarily characterized by uplift near the centerline, with an affected range extending to approximately four times the pipe width on each side. Increasing grouting pressure significantly restrains surface displacement, while excessive jacking velocity exacerbates surface settlement. Moreover, there exists an optimal matching relationship between jacking velocity and grouting pressure that minimizes soil disturbance.
2025 Vol. 62 (5): 243- [Abstract] ( 25 ) [HTML 1KB] [ PDF 3645KB] ( 99 )
251 Application of High-energy Cosmic Ray Muon Imaging Technology in Shield Tunnels
HUANG Liping1 LEI Jiangsong1 SONG Tiantian1 ZHANG Kai2 LV Junpeng2 LOU Zaiming2 LI Kaidi1 ZHANG Jianming3 HAN Ran3
Aiming at the technical challenges of detecting geological anomalies in the overburden strata and early warning of geological hazards during shield tunnel construction, a field test study of muon imaging technology is carried out in a typical shield tunnel project in Shenzhen. By deploying multiple muon detector arrays and applying an improved iterative density reconstruction algorithm, a high-resolution three-dimensional density structure model of the test area is established, enabling accurate localization of density anomalies in the strata. The results show that: (1) this technology can effectively identify density anomalies in geological bodies with a scale of 1-3 m; (2) in the shield-ahead detection mode, the density inversion sensitivity reaches 2%, allowing clear distinction of the physical boundary between moderately weathered and strongly weathered rock; (3) for a tunnel with a burial depth of 18 m, underground cavities with a width of approximately 4 m located 2-4 m above the tunnel crown can be accurately detected (positioning error <2 m), and the enhanced compactness after grouting reinforcement can be verified.
2025 Vol. 62 (5): 251- [Abstract] ( 25 ) [HTML 1KB] [ PDF 5834KB] ( 157 )
259 Experimental Study on the Performance of Synchronous Grouting Materials #br# Using Shield Spoil as Multi-component Substitutions
ZHANG Hongsheng1 ZHU Cheng2 ZHOU Peng3 ZHANG Jian2 WANG Wei1
To address the low utilization efficiency of shield spoil in current tunneling projects, a novel approach is proposed based on a shield tunnel project of Wuxi Metro, in which the retrieved shield spoil is used to replace all of the bentonite and a portion of river sand for the preparation of synchronous grouting slurry. A two-stage component substitution test was conducted, and single-factor analysis was employed to investigate the influence of shield spoil under different substitution schemes on the performance of synchronous grouting materials, thereby verifying the practical feasibility of preparing synchronous grouting slurry using shield spoil. Moreover, an optimized mix proportion meeting engineering requirements was recommended. The results indicate that when only bentonite is completely substituted, the cohesive filling effect of shield spoil enhances the compressive strength progressively, demonstrating its potential for partially replacing sand. It is feasible to replace all bentonite and part of the sand using shield spoil for synchronous grouting in practical applications. The recommended mix proportion is: water-to-binder ratio of 0.96, binder-to-sand ratio of 0.83, powder-to-ash ratio of 2.2, and a mass ratio of shield spoil to water of 0.60. Under this proportion, 42.8% material cost can be saved, and the resource utilization of 1 ton of shield spoil contributes a carbon reduction benefit of 277.66 kg CO2e.
2025 Vol. 62 (5): 259- [Abstract] ( 33 ) [HTML 1KB] [ PDF 5776KB] ( 364 )
269 Experimental Study on Frost-Heave Behavior of Cement-modified Clayey Silt under Different Construction Procedures
GUO Zhijie1 CAO Yi2 REN Meng1 HOU Yingxia1 WANG Yansen2 LIANG Hongzhen1 LI Wei1 ZHANG Ling1
Cement-stabilization technology has been widely applied in ground-freezing construction for municipal  geotechnical engineering due to its effectiveness in mitigating frost heave. However, existing studies have primarily been conducted under standard laboratory conditions, and the influence of construction procedures remains insufficiently understood. In this study, clayey silt from Tianjin was adopted as the research object, and three sample preparation procedures simulating different construction processes (DSC, SC, and SCP) were designed. Frost-heave tests were systematically conducted under varying cement contents and curing ages. The results indicate that cemented soil prepared using the DSC procedure exhibits a “frost-shrinkage-frost-heave-stabilization” evolution pattern, while SC specimens show only slight frost shrinkage at high cement contents, and SCP specimens yield the highest frost-heave ratios overall. Frost heave is negatively correlated with both cement content and curing age, with the former having a more significant impact. The sensitivity of frost heave to cement content follows: SCP > SC > DSC, whereas the sensitivity to curing age follows: SC > DSC > SCP.
2025 Vol. 62 (5): 269- [Abstract] ( 19 ) [HTML 1KB] [ PDF 7752KB] ( 72 )
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