Vertical-inclined alternating composite steel pipe pile(VIACP) is a new green foundation pit support technology. A numerical experimental study on the mechanical properties of vertical-inclined combination piles with different pile inclination angles and lengths was carried out with a foundation pit in Longli County, Guizhou Province, as the research object. Results demonstrate that the VIACP reduces maximum deformation by 57.8% (20.07 mm) compared to traditional cantilever piles (47.57 mm), aligning closely with field monitoring data (16.94 mm). The parametric study shows that the maximum horizontal displacement of the pile decreases and then increases as the inclination angle (5 degrees-30 degrees) increases, with the minimum displacement (20.07 mm) at 20 degrees, which is the optimum angle. Increasing pile lengths lead to progressively reduced displacements followed by stabilization while alternating long-short pile configurations exhibit synergistic effects. Mechanically, axial forces and lateral friction resistance show negative correlations with inclination angles, while bending moments adopt an S-shaped distribution along pile depth with minimal sensitivity to angle variations. Mechanism analysis highlights that the inclined piles in the structure have a pull-anchor effect, the soil between the piles together has a gravity effect, and the alternating arrangement of piles has a spatial structure effect. The three major effects increase the stiffness and stability of the support structure, which is conducive to the deformation control of the foundation pit. The research results will provide a theoretical basis for the popularization and application of the structure.

This study proposed a novel experimental platform to conduct dynamic loading tests of a truncated model steel catenary riser (SCR) within the touchdown zone (TDZ). The facilities of the platform, including a soil tank, a loading system, and a soil stirring system, are introduced in detail. A steel pipe with the same diameter as the in situ SCR has been used in the laboratory tests to investigate the vertical motion of the pipe and the effect of the trench on the lateral motion. As the amplitude of the vertical motion increases, the depth of the trench deepens, the bending moment range increases, and the excess pore water pressure at the bottom of the pipeline first accumulates and then dissipates during loading. The development trend of the trench depth and the influence of the soil strength on the SCR bending moment are also studied. During the test, a seabed trench develops, and its shape is similar to that of the in situ trench.

Wind energy offers significant advantages over fossil fuels, including extensive energy storage and environmental sustainability. Offshore wind turbines serve as the primary technology for harnessing offshore wind power. However, the corrosive effects of the marine environment pose serious threats to their safety and stability. This paper provides a comprehensive overview of corrosion issues affecting steel pipe pile infrastructure, focusing on the following key aspects: (1) Differentiating corrosion mechanisms under various environmental conditions, (2) analyzing the comprehensive corrosion response, particularly the changes in mechanical properties of the pile-soil interface and the bearing capacity of steel pile foundations, (3) summarizing the patterns and trends in corrosion processes to offer theoretical insights for engineering design, and (4) reviewing commonly employed corrosion prevention methods and their respective applicability in relation to specific corrosion mechanisms and responses.

The structural integrity of buried pipelines is threatened by the effects of Permanent Ground Deformation (PGD), resulting from seismic-induced landslides and lateral spreading due to liquefaction, requiring accurate analysis of the system performance. Analytical fragility functions allow us to estimate the likelihood of seismic damage along the pipeline, supporting design engineers and network operators in prioritizing resource allocation for mitigative or remedial measures in spatially distributed lifeline systems. To efficiently and accurately evaluate the seismic fragility of a buried operating steel pipeline under longitudinal PGD, this study develops a new analytical model, accounting for the asymmetric pipeline behavior in tension and compression under varying operational loads. This validated model is further implemented within a fragility function calculation framework based on the Monte Carlo Simulation (MCS), allowing us to efficiently assess the probability of the pipeline exceeding the performance limit states, conditioned to the PGD demand. The evaluated fragility surfaces showed that the probability of the pipeline exceeding the performance criteria increases for larger soil displacements and lengths, as well as cover depths, because of the greater mobilized soil reaction counteracting the pipeline deformation. The performed Global Sensitivity Analysis (GSA) highlighted the influence of the PGD and soil-pipeline interaction parameters, as well as the effect of the service loads on structural performance, requiring proper consideration in pipeline system modeling and design. Overall, the proposed analytical fragility function calculation framework provides a useful methodology for effectively assessing the performance of operating pipelines under longitudinal PGD, quantifying the effect of the uncertain parameters impacting system response.

Combined with the research results of shaking table test, through the deformation performance of steel pipe pile foundation, the seismic damage and seismic performance of steel pipe high pile wharf are evaluated, and the appropriate evaluation method is given. By setting the numerical analytical model of multi working condition steel pipe high pile wharf with different water depth, different pile types and different pile diameters, the limit displacement of the pile in the soil under different ground motions is calculated. The calculated results show that, the plasticity ratio (defined as mu = delta u/delta y) of the structural system of steel pipe high pile wharf ranges from 1.5 to 3.0; and the fitting relationship between plasticity ratio mu and the diameter thickness ratio D/t was obtained. The fitting relationship is tested by the existing experimental research results. The results show that the given fitting relationship can be in good agreement with the experimental results in the range of +/- 15%. On the basis of this fitting relationship, taking the diameter thickness ratio as the basic parameter, a seismic damage evaluation method of steel pipe high pile wharf structure based on deformation performance is proposed.

This paper introduces a novel framework for developing reliable probabilistic predictive corrosion growth models for buried steel pipelines using pipeline inspection data. The framework adopts a power -law function of time model formulation, accounting for nonconstant damage growth rates, and considers the correlation between defect depth and length growth models. The proposed framework explicitly incorporates local influential soil properties in the model formulation; thus, it requires no segmentation and homogenous defect growth assumption and provides defect -specific growth models. The framework is applicable regardless of the availability of matched or non -matched defect data. For corrosion initiation time estimation, two different approaches are proposed: one is to use a Poisson process to account for defect occurrence, which can also predict newly generated defects since the last inspection, and the other is to use multivariate linear regression of soil and pipe properties. The statistics of unknown model parameters are assessed using a Bayesian updating framework in which the model error can be incorporated. The proposed framework is applied using two different sets of data: one set of inline inspection (ILI) data and one set of field excavation data. A case study is conducted, where timedependent system reliability of an in-service pipeline is assessed considering small leak and burst failure modes using the developed defect growth models. The impact of the growth model accuracy on the probability of failure is investigated, and the importance analysis is performed to identify the most influential random variables to the probability of failure.

Gas-buried steel pipes are exposed to various types of corrosion during their service life, and as a result, their initial resistance is significantly reduced. In most previous studies, the seismic vulnerability analysis of these pipes has been done without considering corrosion. The present study evaluates the seismic vulnerability of gas-buried steel pipes and extracts fragility curves considering pipe corrosion. Due to the impossibility of objectively observing the corrosion rate of pipes, a probabilistic model is presented considering the random effect in pipeline corrosion, and for different percentages of corrosion, the critical corrosion range is calculated. Then by modeling the corroded pipe in the soil and applying earthquake acceleration to it, incremental dynamic analysis (IDA) is performed in ABAQUS software and IDA curves are obtained. In the following, the probability of exceedance curves for strain are extracted, and the probability of vulnerability for different pipe corrosion conditions is determined. Finally, the seismic fragility curves of the pipeline showing the probability of failure (POF) as a function of peak ground acceleration (PGA) are obtained. The results show that corrosion percentage, variety of corrosion points, and PGA, strongly affect the uncertainty of strain data and subsequently the probability of failure of the pipeline system. For PGA = 0.4 g, in the case of a healthy pipe, the probability of exceeding the failure criterion strain is close to zero, while this probability is close to 80% for a pipe with average corrosion of 60%.

In recent years, there has been an increasing necessity for monitoring facilities like gas or water pipelines to ensure high security and adequate infrastructure maintenance. The pipeline network is very large, and the main problem is its continuous monitoring. In particular, there is the necessity to monitor the cathodic protection (CP) voltage, which ensures maintaining the pipeline under a state of protection from corrosion and avoids considerable damage to the infrastructure. A communication channel is necessary to monitor the pipeline network continuously. Most of the pipeline monitoring systems make use of wireless communication, like global system for mobile communications (GSM) or general packet radio service (GPRS) technology and even Wi-Fi, to transmit the measurements. By their nature, the implementation of these systems is often expensive and furthermore, not all the pipeline is covered by the signals of the mobile operators. In this article, the communication approach is presented, and, in particular, the pipeline is used as a communication channel. Due to the challenges of pipelined transmission, an identification of the characteristic impedance of the medium must be conducted to obtain the best possible performance. This value is used to design a circuit that can match the function generator output to the impedance of the communication channel. The circuit to be made must allow bidirectional communication of the half-duplex type. Given the low frequencies that can be used for communication on the pipe, a low-frequency circulator must be created. Given the frequencies involved, the bidirectional circuit will be composed of operational amplifiers. The presented circulator allows matching the signal generator output impedance with the pipeline input impedance, to obtain an improvement in the transmission distance achievable using the pipeline as a communication channel.