Flexible plastic pipes are widely deployed in urban drainage networks, yet aging and construction irregularities lead to corrosion, leakage, deformation, and joint failures. Cured-in-Place Pipe (CIPP) rehabilitation installs a resin-cured liner inside the host pipe to form a composite system, whose mechanics for plastic hosts remain insufficiently quantified. This study integrates OFDR-based distributed strain sensing, parallel-plate loading tests, and a validated 3D finite-element model with a cohesive interface to interrogate the effects of the liner-to-pipe thickness ratio beta, pipe diameter D, and modulus ratio eta = Ea/Eb on ring stiffness, bending-moment sharing, and interfacial stresses. Results show that interfacial bonding is the key lever for composite action: ring stiffness was observed to increase monotonically with beta, by approximate to 92 % and approximate to 210 % in the DN315 PE series relative to the beta = 0.15 baseline, whereas non-bonded interfaces yield much lower stiffness. Neutral-axis migration with increasing beta or eta explains the measured strain patterns. At a fixed deformation, D mainly sets demand, while moment partition is governed by beta and bonding. Coaction of interface shear with tensile radial stress at the crown/invert was identified as the primary driver for debonding, consistent with the closed-form and FE stress fields. Two simplified relations are proposed for ring-stiffness enhancement and bonding-induced moment amplification; predictions agree with tests and FE trends within the calibrated ranges beta is an element of[0.15, 0.70], eta is an element of[0.14, 0.47], andD = 250-500 mm. The findings provide design guidance for specifying liner thickness and verifying interfacial bonding in CIPP rehabilitation of plastic pipelines.

Curved pipe jacking is a satisfying technique for laying the buried pipeline in trenchless crossing scenarios. Estimation of frictional resistance in curved pipe jacking exhibits a more complex pipe-soil interaction compared with linear drives. Deflection differential equations for curved pipes embedded on a Pasternak foundation are established, and the finite difference method is used for estimating the foundation reaction force and frictional resistance. As verified, the proposed model exhibits good rationality compared to a practical drive. Parametric analysis indicates that small-radius curvature induces a larger foundation deformation, while the easement curvature restricts the constraints influence of pipe boundaries on frictional resistance along the axial direction. Limited pipe diameter weakens the influence range of the foundation reaction force on the normal pipe-soil interaction. The axial force transfer within the shear layer diminishes as the foundation reaction coefficient enlarges, while the integral value of the foundation reaction follows a decrease-then-increase pattern. Moreover, increased shear stiffness enhances the force transfer performance among the soil springs in the shear layer, but declines the normal contact behavior between the pipe and foundation, contributing to an expanding frictional resistance.

Global cities face mounting challenges in sustaining vast, interdependent infrastructure networks under fiscal and environmental pressures. Conventional optimization methods fail under the dimensional explosion of multi-year maintenance and renewal planning for hundreds of thousands to millions of assets. We present a nested-block optimization framework that decomposes city-wide networks into coordinated sub-blocks, transforming an intractable decision space into a solvable, parallelizable structure while preserving budgetary and temporal constraints. At million-asset scale, the framework achieves rapid convergence and fully feasible plans, far surpassing existing methods in efficiency and scalability. Its architecture unifies diverse assets including roads and pipelines, extends to energy or transit systems, and enables cross-asset, cross-scenario coordination through clustering by district, jurisdiction, or asset class. The framework provides a systematic tool for identifying key evolutionary patterns, evaluating investment pathways, and anticipating system transition conditions, while embedding equity objectives alongside efficiency. These results offer a scientific perspective on urban evolution and practical pathways toward more coordinated, just, and sustainable infrastructure management.

The rehabilitation of aging municipal pipeline increasingly relies on thermoplastic Formed-in-Place Pipe (FIPP) liners; however, predicting their service life remains a critical scientific challenge due to the complex, non-linear coupling of thermal and mechanical creep over decades of service. This study presents a unified, multi-scale method that establishes a cross-scale correlation between molecular viscoelasticity and structural performance. A dual-path accelerated testing strategy is introduced to populate a sparse dataset, which is then synthesized using a Physics-Informed Neural Network (PINN) embedded with Burgers constitutive constraints. The proposed approach successfully constructs a probabilistic creep master curve spanning 100 years (R2 = 0.91). When applied structurally, this framework predicts liner deformation with a relative deviation of only 3.3% compared to experiments conducted at full scale. Finite element models based on these parameters highlight a counter-intuitive trend. Confined FIPP liners experience major stress relaxation, with internal stress dropping by 74% over 100 years. This phenomenon shifts the dominant failure mode from material rupture to geometric instability. Furthermore, it is demonstrated that the system's longevity is governed primarily by the soil-structure interaction rather than the liner's intrinsic stiffness. These findings challenge conventional modulus-based design factors and provide a validated, physics-grounded assessment system for the lifecycle management of underground composite infrastructure.

Accurate prediction of water hammer pressure is vital for the safety of pressurized pipe networks. Conventional calculation methods often fail to account for the nonlinear coupling of multiple defects, such as erosion, scaling, and leakage, that develop during long-term service. This work presents a unified framework integrating experimental modeling, a physics-based numerical solver, and a gradient boosting decision tree (GBDT) algorithm to address this challenge. Applied to acrylate polymer blended with poly(vinyl chloride) resin pipes, the framework incorporates complex parameters encompassing pipe dimensions, defect geometries, and operational conditions. Experimental validation confirms that the baseline numerical model accurately captures transient responses. Extensive coupled simulations reveal that water hammer pressure amplification is highly scenario dependent, ranging from approximately 1.25 to 2.2 times the initial steady-state pressure depending on the specific combination of scaling severity and erosion levels. A pivotal finding is the dual role of erosion; while its direct effect on peak pressure is modest, the resultant increase in the diameter-to-thickness ratio profoundly intensifies fluid-structure interaction, shifting the failure risk from pure overpressure to coupled pressure-structure instability. In contrast, leakage primarily serves as an energy dissipation mechanism, attenuating wave amplitude. The developed GBDT model demonstrates exceptional capability in learning the complex mappings from multi-defect parameters to extreme pressures, achieving an R-2 of 0.99 on a comprehensive high-fidelity numerical dataset. This unified framework bridges hydraulic transient analysis with defect mechanics and data-driven intelligence, providing a robust tool for risk assessment in aging pipe infrastructure.

Aging pipeline infrastructure presents a significant global challenge, particularly within urban water management systems. Fiber-reinforced composite liners have emerged as a trenchless and economical solution for pipeline rehabilitation. However, the mechanical reliability and long-term structural integrity of these liners, especially when cured at ambient temperature, remain insufficiently understood across multiple scales. This knowledge gap currently hinders their widespread adoption in engineering practice. This study presents a comprehensive multiscale investigation into ambient-cured composite liners, employing material characterization, mesoscale damage analysis, and full-scale structural modeling. Microscale analyses highlight that the quality of interfacial bonding between the resin and fibers critically influences damage initiation mechanisms. At the mesoscale, simulations reveal the efficacy of felt-reinforced configurations in dispersing loads and delaying crack propagation. Macroscale finite element analysis further identifies the optimal fiber orientation, weaving angle, and felt thickness to maximize mechanical stiffness and minimize structural deformation. Compared to conventional heat-cured systems, ambient-cured liners demonstrate comparable stiffness and load-bearing performance when interfacial bonding is optimized. These results provide a mechanistic explanation for the variability in previous experimental findings and delineate an engineering design envelope for reliable liner deployment. The findings offer a physics-informed framework for the performance-based design of sustainable rehabilitation technologies in aging pipeline networks.

Jacking prestressed concrete cylinder pipe (JPCCP) has bell-spigot joints and a multilayer composite structure, making jacking force transfer at the pipe end mechanically complex. In particular, local stress redistribution and damage evolution under non-full section loading and pipe deflection remain insufficiently understood. To address this issue, this study combined in-situ monitoring tests with three-dimensional finite element simulations based on the largest-diameter JPCCP project in China. The results show that jacking force transfer across adjacent pipe ends within the launch shaft was generally continuous, although the pipe end response exhibited overall continuity but local non-uniformity owing to the partial-contact loading of the U-shaped loading ring. During the normal jacking stage, pipe deflection and alignment correction further intensified the non-uniformity of axial load transfer in the joint region. The inverted jacking force and local axial strain ratio derived from axial strain effectively characterized the jacking force transfer level and eccentric loading characteristics. Numerical analysis further showed that the loading range of the loading ring significantly affected the initial load-introduction mode at the pipe end, whereas its influence gradually weakened with increasing transfer distance. Under deflection, increasing jacking force and deflection angle aggravated local stress concentration and stress non-uniformity at the pipe end, while increasing the thickness of the wooden pressure ring produced only limited improvement. Circumferential cracking induced by tensile stress in the inner concrete was identified as the dominant damage manifestation at the spigot end, and jacking force transfer non-uniformity was found to be the primary mechanism governing its evolution. These findings provide a theoretical basis for structural design and bell-spigot joint safety assessment in JPCCP projects.

In deep-buried, large-section pipe jacking construction, the pronounced nonlinearity and time-varying nature of the pipe-soil-slurry contact relations make the pipe's stress evolution mechanism highly complex. For the more complex structure of jacking prestressed concrete cylinder pipe (JPCCP), the coupling between external contact pressure and structural response is even more pronounced; however, research in this area remains notably scarce. Based on China's largest-section JPCCP project, this study investigates the dynamic coupling mechanisms between surrounding pressure and structural deformation of pipe through integrated field test and threedimensional numerical simulation. Field monitoring reveals that slurry pressure is one of the critical factors influencing the stress state of the pipe, with contact pressure exhibiting marked spatial and temporal heterogeneity. During the high-pressure grouting phase, the hoop strain of the pipe exhibits a strong negative correlation with contact pressure, whereas the slurry dissipation phase demonstrates a general trend toward tensile drift. Numerical simulations further elucidate the boundary transformation mechanism of slurry as a 'flexible load': adequate slurry pressure can induce a hydraulic sleeve effect, effectively mitigating tensile stress at the pipe springline and transitioning the pipe hoop stress from localized tension to global compressive. However, the partial contact due to pipe flotation causes the peak contact pressure at the pipe crown to increase by about 27.3%. Regression analysis confirms the stable linear negative correlation between contact pressure and hoop stress (R2 approximate to 0.71, response rate is about 0.116 MPa/100 kPa), which serves as a critical strategy for actively controlling the structural safety margin of deep-buried pipe. These findings offer a theoretical foundation for structural safety management and the optimization of grouting parameters in large-section pipe jacking operations.

With the increasing construction of ultra-long tunnels, complex and highly variable geological conditions along tunnel alignments pose major challenges to geological investigation, design, and construction. Conventional vertical drilling mainly provides discrete vertical geological profiles and is limited in its ability to continuously characterize lithological variations, fracture zones, and groundwater conditions along the tunnel axis. To overcome this limitation, this study proposes an integrated investigation approach based on horizontal directional drilling (HDD) for continuous along-axis geological exploration. Using the Tianshan Shengli Tunnel as the geological setting, the technical advantages of HDD for tunnel investigation—including ultra-long reach, ultra-high accuracy, high penetration rate, and strong adaptability—are first summarized. An integrated investigation method is then developed by combining HDD with targeted borehole coring, hydraulic fracturing, comprehensive borehole logging, and borehole TV imaging. A 2271 m long investigation borehole was drilled along the tunnel axis from the portal section. As a result, precise directional control limited the maximum deviation between the HDD borehole trajectory and the tunnel axis to only 6.32 m. Meanwhile, the lag distance between cuttings was determined through theoretical calculations to reconstruct the true borehole positions corresponding to the collected cuttings. Based on XRD mineralogical analysis, macroscopic observations, and preliminary investigation results, the lithology of the tunnel surrounding rock was delineated with high resolution. In addition, daily borehole inflow was monitored, and tunnel inflow during construction was predicted using the groundwater dynamics method and an empirical railway relationship, yielding an expected normal inflow of 4016.6 m3/d and a maximum inflow of 12,049.8 m3/d; furthermore, borehole TV footage was used to accurately locate inflow points and intervals with well-developed joints and fractures within the surrounding rock. Highlights This study proposes an HDD–downhole geophysics method for tunnel investigation, classifies surrounding-rock lithology from cuttings and cores, and predicts tunnel construction inflow from HDD borehole inflow monitoring data.

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.

The shear behavior of the pipe-soil interface determines the frictional resistance of pipe jacking. In the interfacial direct shear tests of well-graded dense sand against steel pipe under both unlubricated and lubricated scenarios, the shear stress initially exhibits hardening followed by softening. The shear band forms in the hardening stage, and significant morphology of the shear band varies in the softening stage. Eventually, the shear band exhibits a bell-shaped distribution in the pattern of horizontal displacement influenced by boundary conditions and fabric anisotropy. Coarse particles exhibit greater displacement and more intense softening due to larger initial void ratios and rotational radius, while specimens with more fine particles possess smaller maximum vertical displacement away from the interface and larger critical interface friction angle. Increased normal stress restricts particle displacement, resulting in larger shear displacement at peak state, more severe particle breakage, reduced shear band thickness, and increased peak interface friction angle. The shear stress reaches the critical stage earlier with bentonite slurry (omega = 6 %) due to reduced dilatancy and particle breakage. When the slurry concentration exceeds 14 %, overall sliding of particle displacement occurs instead of the layered distribution with increased vertical particle movement and noticeable stress softening. Continuous accumulation of irreversible dilation might induce forward movement of overlying soil. Moreover, excessive slurry concentration increases hardening and interfacial friction coefficient.

Schmidt hammer rebound method, a rapid technique for predicting uniaxial compressive strength (UCS), is extensively utilized in rock engineering. However, initially designed for concrete testing, this method encounters limitations when adapted for rock testing due to pronounced differences in density, mineral matrix strength, and anisotropy between concrete and rocks. Consequently, this paper introduces an innovative integrated optimization design approach that combines a Kriging surrogate model with a hybrid particle swarm optimization and gray wolf optimization (PSO-GWO) algorithm. The optimization objectives focus on minimizing damage to samples post-testing, enhancing sensitivity to different lithologies, and strengthening the correlation between rebound height (RH) and UCS. After identifying the relevant design parameters, the proposed method obtains responses and deviations within the range of design parameters, even with limited experimental data. Recognizing that rock is a damaged material, this study establishes a method to quantify the initial damage (Di) of rock samples. The sensitivity analysis elucidates the actual impact of Di on the objective functions and the interplay among design factors. Finally, accounting for the trade-offs between optimization objectives and practical applications, a set of Pareto optimal solutions and uncertainty predictions are generated for laboratory and in-situ testing conditions, respectively. This enables decision-makers to select solutions that align best with their specific research requirements and priorities. This research not only offers innovative perspectives on the application of the Schmidt hammer in rock mechanics but also presents a feasible solution for optimizing measurement equipment for damaged materials, such as rocks.

Reinforced concrete (RC) drainage box culverts are critical to urban infrastructure; however, prolonged service exposure increases their vulnerability to cracking and deterioration, compromising structural safety. This study combines laboratory three-edge bearing tests (TEBT) and finite element analysis (FEA) to evaluate the mechanical properties. It systematically investigates the pipe structural behavior of RC box culverts before and after rehabilitation with GRP liner. The load-bearing performance, failure mechanisms, and deformation responses were comprehensively analyzed. Experimental and numerical results indicate that the GRP liners markedly enhance the load capacity, stiffness, and ductility of the culvert. Compared to the unreinforced culvert, the GRPrehabilitated specimen achieved a 67 % increase in ultimate load (53.6 kN versus 32.1 kN), and 3.6 times increase for the initial stiffness. The unreinforced culverts primarily exhibited bending and shear-induced cracking failures, while the reinforced specimens predominantly showed interface debonding and cracking. FEA predictions agreed within 5 % of experimental results. Based on the FEA results, the effects of GRP elastic modulus, wall thickness, mortar strength, interface bonding condition, and liner placement were further evaluated. Sensitivity analysis showed that interfacial bonding strength had the greatest influence on structural performance with a sensitivity index of 74.7 %, followed by liner position and thickness. This study provides theoretical insight and engineering recommendations for the repair design and material selection optimization of RC box culverts.

Machine learning (ML) methods for predicting the uniaxial compressive strength (UCS) of rocks, while established, face challenges in integrating diverse geological data and dataset imbalances. This study introduces a novel Hybrid Bayesian-Group-based Machine Learning (HB-GML) method that combines Bayesian ridge regression for imputing missing data with a dynamic grouping strategy for data clustering. Utilizing a dataset of 487 samples from various lithologies, the Bayesian ridge regression was used to impute missing values, ensuring the reliability and uncertainty of the estimates were analyzed. Furthermore, the K-Nearest Neighbor-Density-based Spatial Clustering of Applications with Noise (KNN-DBSCAN) algorithm effectively clustered data into distinct groups, each reflecting its underlying data distribution and identifying noise points, without manual intervention. For each cluster, the HB-GML method identified the most optimal ML model by comparing evaluation indices across various techniques, ensuring model reliability and accuracy. The final model, integrating optimal models from all clusters, is expected to enhance predictive performance and model interpretability. Comparative analysis shows that the HB-GML method effectively clusters data based on intrinsic characteristics, offering a robust and adaptable framework for enhancing data processing, as well as significantly enhances predictive accuracy. The method's adaptive clustering strategy not only avoids data imbalances but also adapts dynamically to new data, providing a reliable solution for the practical application of ML methods in geotechnical engineering.

Jacking prestressed concrete cylindrical pipe (JPCCP) is an innovative pipe that combines the benefits of prestressed concrete cylinder pipe (PCCP) and the pipe jacking method, playing a crucial role in water conservancy projects across China. Due to its structural characteristics and manufacturing process, the JPCCP joints are prone to circumferential cracks during jacking, and the harmful cracks can damage the inner concrete core over time, posing significant safety risks to the pipeline's structural integrity. To investigate the influence of jacking factors on cracking behavior at the JPCCP joints, this study examines the failure modes of concrete at the bell-spigot ends of the pipes. The analysis combines field experiments and numerical simulations, using data from China's largest diameter JPCCP project. The study finds that local tensile stress at the spigot end is the primary cause of cracking and potential fracture, and micro-cracks initially form on the inner surface of the damaged region, progressing circumferentially. Both the jacking force and deflection angle significantly affect the distribution and magnitude of the maximum principal stress in the concrete. The ultimate jacking forces for deflection angles of 0.1 degrees and 0.5 degrees are 3842 T and 1134 T, respectively. Controlling concrete cracking can be achieved in the construction process by reducing the relative deflection between adjacent pipes. This study introduces novel approaches for improving JPCCP construction techniques and optimizing joint design, providing valuable insights for future projects.

The implementation of large-diameter flood diversion pipelines in urban areas serves as an effective strategy to address urban waterlogging issues, which can enhance the resilience of cities to a certain extent against extreme precipitation events. This case study delineates the Zhengzhou Jinshui River flood diversion project, which employs the ultra-large-buried jacking prestressed concrete cylinder pipe (JPCCP), offering a summary and analysis of the pipe design and construction technologies employed in the JPCCP project within collapsible loess stratum, and the study also analyzes the pull-back scheme of the incident involving the front-end sinking of the machine head. Through on-site monitoring experiments, the variation patterns of contact pressure and slurry pressure of large-diameter JPCCPs were analyzed. The results demonstrate that the trends in contact pressure and slurry pressure exhibit a general consistency. During the jacking process, the pressure around the pipe can be categorized into three distinct phases based on grouting frequency or pressure, with notable variations in the pipe–soil–slurry contact state. The difference between the contact pressure and slurry pressure (termed as effective soil pressure) serves as a more accurate method for determining the pipe’s operational state. Moreover, the effective earth pressure at the pipe top demonstrates a higher degree of consistency with the calculation results prescribed by the standards ATV A161 and ASCE 27.

Exploring the quantitative relationship between drilling parameters and rock strength offers valuable data for enhancing rock engineering safety. This study employed a self-designed horizontal directional drilling (HDD) experimental apparatus, using a controlled variable method to examine the effects of thrust force and rock strength on HDD drilling efficiency. The relationship between the total energy consumption of a tricone bit and rock strength was analyzed from an energy perspective. Introducing the concept of mechanical specific energy (MSE), the study established a quantitative relationship between MSE and uniaxial compressive strength (UCS) through data fitting. Key findings include: In tests on six M15-grade mortar specimens, increasing thrust force led to proportional increases in drilling speed and reaction torque. Fluid flow rate correlated positively with rotational speed, while fluid pressure correlated positively with reaction torque, aligning with the positive displacement motor (PDM) operating principles. In tests involving mortar and rock specimens of varying strengths, drilling speed negatively correlated with thrust force as specimen strength increased. At the same time, reaction torque positively correlated with thrust force. The total energy consumption of the tricone bit increased linearly with drilling depth, with higher-strength rock specimens exhibiting steeper slopes, indicating greater energy demand. Data fitting between MSE and UCS produced a correlation coefficient of R2 = 0.91932, demonstrating a strong linear relationship. These findings provide a reliable theoretical reference for applying HDD in tunnel geological investigations and can guide the optimization of drilling parameters for improved construction efficiency and safety.

The spray-applied pipe lining (SAPL) method, extensively employed in the trenchless rehabilitation of reinforced concrete pipes (RCPs) due to its operational versatility, remains constrained by an incomplete understanding of the failure behavior of rehabilitated pipelines, thereby impeding optimal design strategies. This study proposes an analytical approach to evaluate the structural performance of pipes with fiber-reinforced mortar lining, with a particular focus on interface failure and its consequences. Two RCPs with an inner diameter of 1000 mm, repaired with 34 mm and 45 mm centrifugally sprayed fiber-reinforced mortar liners, were subjected to three-edge-bearing (TEB) tests. The elastic limit loads of the two pipes were 57% and 39% of their pre-rehabilitation conditions, while the ultimate loads were 45% and 69%. A thicker liner exhibits a greater susceptibility to interface failure, leading to wider cracks around the elastic stage during loading. Once the interface failure occurs, load redistribution allows the liner to resist further cracking and sustain higher capacity, demonstrating enhanced bearing performance. Critical factors influencing the failure process were analyzed to inform design optimization, revealing that improving the interface takes precedence, followed by thickness design.

The erosion of cohesive soils is regarded as one of the major threats to the failure of earth structures. The current evaluation of clay erodibility is primarily based on empirical correlations with other physical and mechanical soil properties, which lack a fundamental understanding of multiscale resistance formation under complicated environmental conditions. In this study, the hole erosion test (HET) was conducted using our augmented testing system, which includes sample preparation equipment and a temperature control unit. The kaolinite specimen is prepared following the saturated preconsolidation approach under defined stresses, which significantly improves the test repeatability. In total, 33 specimens are prepared and tested using the enhanced HET system under varying preconsolidation pressures, temperatures, and fines contents with triplicates for each case. The erosion resistance of clay increases with the preconsolidation pressure, and macropores are destructed into micropores, as revealed by the mercury intrusion porosimetry (MIP) test and the specific surface area analyzer. The scanning electron microscopy (SEM) images indicate an anisotropic aggregate structure prepared using the preconsolidation approach, which possesses different erodibility indices in different flow directions. With the increase in temperature from 10 degrees C to 40 degrees C, the critical shear stress decreases from 292 to 131 Pa (or by 55.1%). The addition of quartz sands in the kaolinite clay undermines the soil erosion resistance.