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Cured-in-place pipe (CIPP) lining is a widely adopted method for pipeline renewal, offering advantages such as rapid installation and cost-effectiveness. However, concerns regarding the environmental impacts of volatile organic compound (VOC) emissions during the installation process have raised issues regarding the CIPP method. The literature review conducted in this paper indicated the need for stringent monitoring and management practices to mitigate adverse effects, emphasizing the importance of safe installation protocols. This paper presents the initial results of a case study focusing on VOC emissions, specifically investigating non-styrene vinyl ester resins and water curing. To capture emissions from CIPP activities, the methodology involved air sampling using various equipment, including photoionization detectors (PID), summa canisters, passive worker sampler sorbent tubes, and method 13 cartridges. The preliminary findings indicate that non-styrene vinyl ester resins resulted in VOC emissions well below the exposure limits set by OSHA and USEPA, with the highest measured concentration being 2.54 ppm. This demonstrates that non-styrene resins can significantly reduce environmental and health risks. The future phases of this project will explore different resins and curing methods to further validate these findings and develop comprehensive guidelines for safe CIPP installations. [ABSTRACT FROM AUTHOR]

Abstract Corrosion is one of the most common forms of damage to pressure pipes. CIPP liner can improve the mechanical properties of the pipe with corrosion. It is very important to study the mechanical response of corrosion pipes rehabilitated by CIPP liner. In this study, a three-dimensional finite element model of a pressure pipe rehabilitated with CIPP liner under the condition of circular corrosion is established, and the model is evaluated by using the experimental and analytical results. Afterward, the influence of each parameter on the stress and displacement of the liner is analyzed. Finally, the liner stress calculation equation is obtained based on 870 sets of data. The results show that the finite element results are in good agreement with the experimental and analytical results. The maximum stress of the liner first occurs at the center of the corroded circle, and as the corrosion diameter increases, the maximum stress gradually shifts to the edge. The maximum stress of the liner increases first and then tends to be stable with the increase of the corrosion diameter, and the friction coefficient has little effect on the liner stress.

Super-large-diameter caissons, serving as working wells for trenchless pipe jacking technology, are being extensively constructed alongside the increasing adoption of trenchless technology in urban areas. However, being regarded merely as ancillary structures, the structural stability of a caisson during both construction and operation phases are often neglected. This study, centered on the super-large-diameter caissons within the Jinshui River flood control project in Zhengzhou, China, systematically monitored the mechanical behavior of caisson structures and surface settlement during construction and operational phases. Utilizing a validated FE method, the influence of groundwater fluctuations on the structural stability of caissons during operational phases was examined. Furthermore, potential occurrences of loose soil, voids, and caisson tilting were considered. Subsequently, the applicability of permeable polymer, foam polymer, and anchor rod reinforcement techniques were evaluated, followed by an analysis of the structural stability of the caissons post reinforcement during long-term operations. The findings demonstrate the minimal horizontal displacement of and stress variation in caissons under seasonal groundwater fluctuations, without significant structural alterations. Nevertheless, the presence of loose soil, voids, and caisson inclinations may decline the caisson's support force and bearing capacity. With the increase in non-compactness, void size, and inclination, the structural stability of caissons notably diminishes. Reinforcing loose soil with permeable polymers, filling voids with foam polymers, and utilizing anchor rods are all effective methods for strengthening caisson structures and enhancing their stability. [ABSTRACT FROM AUTHOR]

The spraying method offers the advantages of environmental protection, convenient construction, and cost-effectiveness, making it widely used in pipeline structure repair. Given the complex service environment of pipelines, there is an urgent demand for high-strength and durable spraying materials. To achieve this goal, a PVA fiber reinforced cement mortar material (PFCM) with high early strength, excellent impermeability and stable acid corrosion resistance was developed through orthogonal test design. The optimal material was obtained through factors such as setting time, fluidity, compressive strength and flexural strength. The effects of the contents of fly ash, redispersible polymer powder and PVA fiber on the working and mechanical properties of the material were investigated, and further research was conducted on its tensile strength, impermeability, acid corrosion resistance. In addition, Thermogravimetric-differential Thermal Analysis (TG-DTA) was utilized to analyze the thermal stability of PFCM. X-ray diffraction (XRD) was utilized to analyze the composition of PFCM. Mercury intrusion porosimetry (MIP) was utilized to analyze the pore structure of PFCM, and the feasibility of the PFCM was verified. The results indicate that the contents of fly ash, redispersible polymer powder and PVA fiber have significant effects on the working and mechanical properties. The optimum initial setting time is 60–80 min, and the optimum fluidity is between 170 and 180 mm. The compressive strength and flexural strength of the mortar prepared with the optimum parameters are 102.5 MPa and 20 MPa, respectively. The material has an excellent spraying effect with no sagging, and exhibits high early strength, outstanding corrosion resistance, low porosity, and exceptional impermeability. This study lays the foundation for achieving high-quality spray repairs of underground drainage pipelines.

In box jacking, injecting lubricant around the box is an essential method to reduce excessive friction forces caused by the interaction between the box and soil. This method introduces complexity to factors controlling the friction forces, such as the pipe-soil contact state, earth pressure, and friction coefficient. In particular, during long-distance construction, different lubricant conditions come into play. These intricate scenarios hinder the accurate estimation and control of friction force throughout the entire construction period. This study analyzed the variation patterns of frictional resistance based on monitoring data from two actual cases. The lubricant condition changes during the long-distance jacking process were categorized, the effect of lubricant actions on factors controlling friction force in each segment was discussed, and a new method for calculating friction forces by partitioning the long-distance box jacking was proposed. This approach aims to enhance the prediction accuracy and was compared with the results obtained from existing models. The rationality of the new model was further validated by combining numerical simulation results with field data. The results indicate that the proposed segmented calculation model demonstrates better prediction accuracy when facing variations in actual construction conditions. It can serve as a reference for the process design and construction control of long-distance box jacking. [ABSTRACT FROM AUTHOR]

Cured-in-place pipe (CIPP) lining is a widely adopted method for pipeline renewal, offering advantages such as rapid installation and cost-effectiveness. However, concerns regarding the environmental impacts of volatile organic compound (VOC) emissions during the installation process have raised issues regarding the CIPP method. The literature review conducted in this paper indicated the need for stringent monitoring and management practices to mitigate adverse effects, emphasizing the importance of safe installation protocols. This paper presents the initial results of a case study focusing on VOC emissions, specifically investigating non-styrene vinyl ester resins and water curing. To capture emissions from CIPP activities, the methodology involved air sampling using various equipment, including photoionization detectors (PID), summa canisters, passive worker sampler sorbent tubes, and method 13 cartridges. The preliminary findings indicate that non-styrene vinyl ester resins resulted in VOC emissions well below the exposure limits set by OSHA and USEPA, with the highest measured concentration being 2.54 ppm. This demonstrates that non-styrene resins can significantly reduce environmental and health risks. The future phases of this project will explore different resins and curing methods to further validate these findings and develop comprehensive guidelines for safe CIPP installations.

The rapid growth of population and increasing complexity of urban infrastructure have led to even greater consideration of new methods of installing and commissioning underground facilities. These facilities and vital artery lines are implemented in various ways, the most important of which is the traditional open-trench and new trenchless technology. Many factors affect the selection of the best method of implementation, and the method and technology of implementation should be determined based on the conditions of the project and area of construction. In the present study, the factors affecting the acceptance and application of trenchless technology and open-trench method in Iran are evaluated using two techniques: analytic hierarchy process (AHP) and analytic network process (ANP), and the results are compared with each other. The statistical population for this research consisted of middle managers, contractors, and engineers from Iran's supervision and design body. For this purpose, factors such as technology, economic, environmental, project productivity, organizational, executive management, individual, and demographic are identified as effective factors in the evaluation of excavation technology using library studies and consulting with experts. The relevant decision-making model was then prepared via interviews with experts. Eventually, components and criteria affecting excavation technology were prioritized through pairwise comparisons and model solving. The results showed that, in the AHP technique, the principal components, i.e., economic, technology, and executive management factors, and the criteria section, direct cost, social costs, and competitive business environment factors, are ranked first to third. In the ANP technique, the principal components, i.e., economic, technology, project productivity factors, and in the criteria section, the factors of the competitive business environment, environment, and social costs, are ranked first to third. This comparison shows that the existence of dependencies between the principal components is effective in prioritizing the elements. [ABSTRACT FROM AUTHOR]

Super-large-diameter caissons, serving as working wells for trenchless pipe jacking technology, are being extensively constructed alongside the increasing adoption of trenchless technology in urban areas. However, being regarded merely as ancillary structures, the structural stability of a caisson during both construction and operation phases are often neglected. This study, centered on the super-large-diameter caissons within the Jinshui River flood control project in Zhengzhou, China, systematically monitored the mechanical behavior of caisson structures and surface settlement during construction and operational phases. Utilizing a validated FE method, the influence of groundwater fluctuations on the structural stability of caissons during operational phases was examined. Furthermore, potential occurrences of loose soil, voids, and caisson tilting were considered. Subsequently, the applicability of permeable polymer, foam polymer, and anchor rod reinforcement techniques were evaluated, followed by an analysis of the structural stability of the caissons post reinforcement during long-term operations. The findings demonstrate the minimal horizontal displacement of and stress variation in caissons under seasonal groundwater fluctuations, without significant structural alterations. Nevertheless, the presence of loose soil, voids, and caisson inclinations may decline the caisson’s support force and bearing capacity. With the increase in non-compactness, void size, and inclination, the structural stability of caissons notably diminishes. Reinforcing loose soil with permeable polymers, filling voids with foam polymers, and utilizing anchor rods are all effective methods for strengthening caisson structures and enhancing their stability.

The cured-in-place pipe (CIPP) is a pipe rehabilitation technique that is becoming increasingly popular due to its cost advantages, reduced environmental impact, and decreased time requirements compared to traditional pipe replacement. However, some CIPP rehabilitation projects have revealed deficiencies in predicted liner performance. This paper proposes and validates the Inner Balloon Pressure Test, a new test procedure for the quality control of CIPP rehabilitation liners. The test is intended to replicate the working stress conditions of an installed CIPP liner, and is proposed as an alternative to the curved specimen bending test recommended by the current CIPP standard and which has been shown to overestimate the ultimate stresses of cured CIPP liner specimens by more than 200%. Consequently, in a liner of DN 385 and 6 mm of thickness, a burst pressure of 138.2 bar was predicted through the bending test, whereas 62.8 bar was deducted from tensile tests. The experimental evidence provided in this study can significantly impact the design of CIPP pressure pipe liners. Inadequate sizing of the structural reinforcement can compromise the liner functionality and the rehabilitation of the pipeline. Therefore, this study provides a novel test that reduces uncertainties related to the strength analysis of CIPP liners. Furthermore, it contributes to optimizing and advancing existing design and quality control techniques.

In box jacking, injecting lubricant around the box is an essential method to reduce excessive friction forces caused by the interaction between the box and soil. This method introduces complexity to factors controlling the friction forces, such as the pipe-soil contact state, earth pressure, and friction coefficient. In particular, during long-distance construction, different lubricant conditions come into play. These intricate scenarios hinder the accurate estimation and control of friction force throughout the entire construction period. This study analyzed the variation patterns of frictional resistance based on monitoring data from two actual cases. The lubricant condition changes during the long-distance jacking process were categorized, the effect of lubricant actions on factors controlling friction force in each segment was discussed, and a new method for calculating friction forces by partitioning the long-distance box jacking was proposed. This approach aims to enhance the prediction accuracy and was compared with the results obtained from existing models. The rationality of the new model was further validated by combining numerical simulation results with field data. The results indicate that the proposed segmented calculation model demonstrates better prediction accuracy when facing variations in actual construction conditions. It can serve as a reference for the process design and construction control of long-distance box jacking.

IntroductionClosed-circuit video (CCTV) inspection has been the most popular technique for visually evaluating the interior status of pipelines in recent decades. Certified inspectors prepare the pipe repair document based on the CCTV inspection. The traditional manual method of assessing structural wastewater conditions from pipe repair documents takes a long time and is prone to human mistakes. The automatic identification of necessary texts has received little attention. Computer Vision based Machine Learning models failed to estimate structural damage because they are not entirely understood and have difficulty providing high data needs. Hence, they have problems providing physically consistent findings due to their high data needs. Currently, a very small curated annotated image and video data set with well-defined, precisely labeled categories to test Computer Vision based Machine Learning models.MethodsThis study provides a valuable method to determine the pipe defect rating of the pipe repair documents by developing an automated framework using Natural Language Processing (NLP) on very small, curated annotated images, video data, and more text data. The text used in this study is broken into grammatical units using NLP technologies. The next step in the analysis entails using words to find the frequency of pipe defects and then classify them into respective defect ratings for pipe maintenance.Results and discussionsThe proposed model achieved 95.0% accuracy, 94.9% recall, 95% specificity, 95.9% precision score, and 95.7% F1 score, showing the potential of the proposed model to be used in large-scale pipe repair documents for accurate and efficient pipeline failure detection to improve the quality of the pipeline.

Reinforced concrete pipes (RCPs) were commonly used in older underground pipelines in Taiwan, China. However, their joints are prone to damage, including fracture and separation, from problems such as overloading, poor backfilling, and liquefaction. For the rehabilitation of such aged pipelines, trenchless methods are preferred to minimize the impact on transportation. The cured-in-place-pipe (CIPP) rehabilitation could be one of the most popular trenchless methods suitable for the cases with angular alignment and changing cross-section. However, according to the existing standards, no details are available on the performance of the rehabilitated parts of the damaged pipeline, including the effect of separated joint. This study designed and conducted laboratory testing on the composite pipe joint (the CIPP rehabilitated RCPs with a separated joint) with different scenarios, including radial and longitudinal loading tests. The radial test results indicated that, for a small separation distance, CIPP rehabilitation can restore the original function of a pipeline and improve its hoop strength. The longitudinal test revealed that the damage due to bending was controlled by the tensile strength of the liner material. The ultimate flexural strength decreased as the separation distance increased. However, pipelines may be subjected to additional loads due to flotation or subsidence, for which the longitudinal loading capacity is often the limiting parameter. For such conditions, it is necessary to confirm, by more research, whether the wall thickness is sufficient.

The design of various components of underground trenchless constructions requires geotechnical parameters as inputs. Currently, determination of geotechnical parameters for application in the design of trenchless constructions relies heavily on the standard penetration test (SPT) and corresponding N-value. However, N-values are often misinterpreted in practices, resulting extracted geotechnical parameters poorly representing the true soil conditions. Especially among the numerous empirical methods available related to N-value, it is challenging for practitioners to find an appropriate empirical correlation for their projects. This paper summarizes ten geotechnical parameters that are often required for trenchless design, including internal friction angle, modulus of elasticity, shear modulus, undrained shear strength, modulus of soil reaction, constrained soil modulus, preconsolidation stress, overconsolidation ratio, relative density, and porosity. Empirical methods based on SPT for determining the geotechnical parameters required in trenchless design are reviewed with ninety-eight correlations between the geotechnical parameters and N-value. Furthermore, comparisons between the SPT correlations are made to provide insight on determining the geotechnical parameters. Four laboratory examples from literature sources related to the design of horizontal directional drilling (HDD) are studied to demonstrate the usefulness of the systematic determination of geotechnical parameters using SPT correlations. Compared to geotechnical parameters provided by researchers that conducted the laboratory experiments, geotechnical parameters determined using SPT correlations resulted improvement in precision by 17% for the estimation of maximum allowable annular pressure in HDD. With application of a correction factor that is commonly used among practitioners, the maximum allowable annular pressure estimated using SPT correlations are found nearly equal to the measurements of annular pressure at hydraulic fracture, confirming that SPT-based empirical methods reviewed herein are reasonably reliable for trenchless design. [ABSTRACT FROM AUTHOR]

In recent years, there has been growing interest in trenchless technology, particularly in using centrifugal spraying technology to rehabilitate drainage pipelines. In this study, we evaluated the effectiveness of fiber-reinforced cement mortar spraying materials on pipes using the three-edge bearing test (TEBT) as per ASTM C497 standards. Six conditions of corroded and rehabilitated pipelines were tested: (1) corrosion depths, (2) corrosion widths, (3) corrosion positions, (4) pipe diameters, (5) loading rates, and (6) repair thicknesses. Through the TEBT, the structural bearing capacity and failure form of the pipe before and after repair were compared, and the bearing capacity difference of the pipe under different conditions was studied. Finally, a sensitivity analysis was conducted on the six variables. Among the many factors that affect the reliability of pipe structures, the influence degree of each factor is quite different. Through the parameter sensitivity analysis, the influence degree of each factor on the reliability of the structure can be clarified. The results show that the bearing capacity of the rehabilitated pipes is sufficient to meet the normal pipe bearing capacity requirements. The mortar lining and existing pipes can bear stress jointly, significantly increasing the maximum load of the rehabilitated pipes by up to 55.6 % and correspondingly reducing the circumferential strain. This indicates that the application of the mortar spraying lining layer effectively achieves the purpose of pipeline repair. This study provides valuable guidance for structural design optimization and safe operation. • The bearing capacity of spraying rehabilitation pipelines under three-edge bearing tests. • Normal, corroded and rehabilitative pipes set at TEBT condition. • Considering different corrosion depths, widths, positions, pipe diameters, loading rates, and repair thicknesses. [ABSTRACT FROM AUTHOR]

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• Introduces a novel Genetic Algorithm-optimized BP Neural Network for accurate polymer fracture grouting predictions. • Designs a precise test device to explore fracture and grouting parameters systematically. • The GA algorithm significantly improves the accuracy and robustness of the grouting effect prediction when compared with multiple prediction models. Polymer grouting can effectively improve the stability of surrounding rock fractures. However, in practical construction, it is difficult to judge the degree of coupling between the slurry and the rock, and the effective grouting range after grouting. Therefore, early prediction of the effect of grouting on the surrounding rock is crucial. In this paper, a new artificial intelligence method is proposed to predict the polymer fracture grouting effect. The genetic algorithm optimized back propagation neural network (GA-BP) is employed to construct an intelligent prediction model. To acquire a substantial dataset for constructing the model, an easily assembled/disassembled test apparatus for polymer fracture grouting is designed. The maximum coupling degree of the fractures and slurry diffusion distance are chosen as the evaluation metrics for the grouting effectiveness. The influences of the fracture characteristic parameters and grouting volume on the grouting effect are investigated. Furthermore, a comprehensive analysis is conducted on the spatiotemporal diffusion characteristics and slurry-rock coupling mechanism of polymer grouting. Compared to traditional BP neural networks, and three other machine learning algorithms (decision trees, random forests and gradient boosting decision trees), the GA-BP model outperforms them in terms of R2 (coefficient of determination), MSE (mean squared error), MBE (mean bias error), MAE (mean absolute error) and RMSE (root mean squared error) in both the test and training sets. The GA algorithm significantly improves the accuracy and robustness of the prediction model. The optimized model demonstrates significant accuracy in predicting grouting results and assessing efficiency, providing a practical reference for grouting construction. [ABSTRACT FROM AUTHOR]

• Developed pipe-swallowing technique for pipe replacement in sand. • Evaluated it by monitoring stress, pulling force, and vertical displacement. • Established an equation to predict vertical displacement. Pipe bursting, a trenchless technique for replacing underground pipes, may induce ground movements that potentially harm nearby structures. To address this issue, the innovative pipe-swallowing method has been developed. Compared to pipe bursting, this method reduces surface disturbances and offers better protection for the newly installed pipes. In this study, a uniaxial test machine was employed in preliminary tests to enhance the structural design of the pipe-swallowing device. Follow-up experiments conducted in a 3.0 m × 1.8 m × 1.5 m test box measured the pulling forces and three-dimensional surface displacements involved in replacing a buried HDPE pipe, 315 mm in diameter, with another of the same size. The most effective pipe splitting force, determined as 32 kN, was achieved using three blades with 30° V-edges and 120° intersection angles, leading to the lowest observed peak pulling force. This force predominantly offsets the friction between the new pipe and the soil, the interaction of the swallower with the soil, and the force required for pipe splitting. The pipe-swallowing process leads to persistent alterations in the pressure distribution around the pipe, causing ground disturbances extending roughly ± 650 mm. The maximum vertical displacement measured was 21 mm, aligning with the modified Gaussian distribution model. These findings affirm the practicality of the pipe-swallowing method and pave the way for future improvements in finite element models for this application. Furthermore, expanded research exploring a range of soil types and pipe materials, including both flexible and brittle varieties, is crucial for advancing the efficiency of this technology. [ABSTRACT FROM AUTHOR]

Pipe jacking is a trenchless method for laying pipes, widely employed in micro tunneling and underground pipeline construction. Guiding the pipes during jacking is essential to ensure the pipes and tunnels are laying along the designed trajectory. In light of the challenge posed by the unsuitability and manual operation of current pipe jacking automatic guidance methods for complex pipe jacking, a pipe jacking guidance method based on a fiber optic gyroscope (FOG)/odometer (ODO)/static leveling (SLL) integrated navigation system was proposed in this study. First, a 15-dimensional Kalman filtering model was established to fuse the multi-sensors measurement information according to laying characteristics and motion mode of pipe jacking construction. Secondly, based on the Kalman filter model, the error in the integrated measurement system was minimized by fused measurement information from different working states. When the pipe jacking machine was working, the Kalman filtering model fused the measurement information of ODO and SLL. When the pipe jacking machine was static, zero velocity and zero angular velocity were used. Subsequently, the feasibility of the proposed algorithm was validated through simulating the pipe jacking construction process with PA-GS300 fiber optic inertial navigation system, SD76-C ODO, and PTH-SZY102 SLL. The static experiment results show that the error of the inclination and toolface angles is approximately 0.002°, and the error of the azimuth angle is approximately 0.005°. The horizontal and vertical axis deviations are less than 0.01 mm and 0.16 mm, respectively. In the straight experiment, the inclination angle error is less than 0.07°, the toolface angle error is less than 0.05°, and the azimuth angle error is less than 0.62°. The horizontal and vertical axis deviations are less than 5 mm and 4 mm, respectively. In the curved experiment, the maximum error of the azimuth angle is 1.087°, the average horizontal axial deviation is 31 mm, and the average height deviation is 17 mm. In conclusion, the proposed method could enhance the applicability of the guidance system to complex pipe jacking and obtain measurements with high precision during complex pipe jacking operations. [ABSTRACT FROM AUTHOR]

A three-dimensional (3D) numerical model for polymer grouting in rock mass fractures based on reaction kinetics theory is established in this article. The model integrates polymer reaction kinetics, compressible Newtonian fluid control, the energy balance accounting for foaming agent evaporation, and slurry density and viscosity models. A 3D rock fracture model simulates grouting in complex fractures and is validated by conventional viscosity simulations. In this study, the impact of fracture medium parameters on polymer diffusion is assessed, and slurry flow, pressure, viscosity, and density distributions during grouting are predicted. The research results indicated that (1) wider fractures reduce the overall slurry viscosity, rough fractures yield an uneven viscosity distribution, and smooth fractures (Joint Roughness Coefficient, JRC = 0) exhibit symmetrical viscosity. An increased fracture inclination boosts the slurry viscosity and reduces the reaction time. (2) Compared with viscosity, slurry density inversely trends with distance. (3) Larger fractures exhibit lower overall slurry diffusion pressures, which decrease with distance. Rough fractures experience higher pressure and fluctuations. A greater fracture inclination increases the overall diffusion pressure, with a monotonic increase at 60° and a parabolic distribution at 0°, peaking at the grouting port. [ABSTRACT FROM AUTHOR]

Horizontal Directional Drilling (HDD) is a very complex technology. Although the installation of pipelines by means of this technology is often successful, examples of unsuccessful projects are also known. Due to the complexity of the technology, with the interaction of multiple processes, risks related to uncertainties in these processes play important role. These risks are related to the variability of underground strata, changing natural environment, changes in economic environment, as well as limitations of the equipment, technical disruptions and human factors. This paper describes the risk evaluation results of the FMEA and a Pareto– Lorenz analysis for 14 external risk factors (8 natural or environmental risk factors as well as 6 economic risk factors) in HDD technology. In the proposed approach not only the probability of the external risk factor occurrence was considered, but also its consequences and the ability to detect faults, which were not plainly separated and taken into account in the literature so far. Such an approach has shown the relationship between occurrence, severity and detection for the analysed external failures. Moreover, 40 detection possibilities for the external risks in HDD technology were identified. The calculated risk priority numbers enabled ranking HDD external failures and identified the most critical risks for which the suggested detection options were unsatisfactory and insufficient, and therefore other types of risk response actions need to be explored. [ABSTRACT FROM AUTHOR]

Recent research by Matthews et al. at the Louisiana Tech University Trenchless Technology Center (TTC) regarding styrene emissions produced during steam-cured, styrene-based cured-in-place pipe (CIPP) installation was compared to data from six relevant, independent studies. As part of this analysis, data in the reviewed studies were compared to exposure guidelines published by the Environmental Protection Agency (EPA), National Institute of Occupational Safety and Health (NIOSH), and Occupational Health and Safety Administration (OSHA). Measurement methodology and goals were considered and briefly described in the analysis. Finally, this paper highlights differences and similarities in the conclusions and measurements of the reviewed studies while searching for and identifying conclusions and trends that are common across the reviewed studies. [ABSTRACT FROM AUTHOR]

The construction method of horizontal directional drilling (HDD), by virtue of its high pipe-laying precision, short construction period, strong stratum adaptability, long crossing distance, low construction cost, and other significant advantages, has become the fastest-growing trenchless technology. However, this technology still faces great difficulties in drilling crossing of complicated strata. In particular, crossing failure often occurs when crossing rivers; thus, in the drilling process, it is necessary to accurately predict and calculate the frictional drag and torque before construction. According to surveys, the numerical codes used for drill string strength calculation and frictional drag analysis are mainly developed by North American or European commercial companies, while the development of domestic HDD numerical codes is rarely reported in the literature. Considering that in practical HDD engineering, the actual crossing tracks are spatially tortuous and complicated, this study adopts a dual-model (stiff-string model and ABIS model) for the drill string mechanics calculation, develops a HDD numerical code, and compares the calculation results to on-site measurements. The results indicate that the direct thrust force and torque calculated by the stiff-string model and the ABIS model are within ± 20% of the actual on-site data, while the accuracy of the ABIS model is higher than that of the stiff-string model. The ABIS model is sensitive to well track variations, and thus, it can better reflect their effect on frictional drag in actual drilling. According to the numerical results, the adopted bottom hole assembly (BHA) is ultimately restricted by buckling stability, and the calculated distance is consistent with the actual crossing length. According to the calculated stress results, the BHA adopted in practical engineering can meet the strength and safety conditions, which are consistent with the drill string strength state met in practical crossing. The results suggest that this software can satisfactorily simulate HDD mechanics and perform strength calculations, providing a relatively high accuracy. [ABSTRACT FROM AUTHOR]

Many utility owners in the United States are actively searching for new and innovative rehabilitation techniques to help them regain control and repair large tracts of their networks; moreover, traditional open cut replacement is too costly and slow to keep up with demand. Many trenchless techniques such as Spray-In-Place Pipe (SIPP) lining have been adopted by municipalities to renew their aging pipeline systems. The further development of SIPP linings could benefit the water community in the United States and around the world. SIPP lining could play a key role in controlling the future expected burden caused by the aging distribution networks. This study aimed to investigate the mechanical properties of a newly proposed reinforced spray in place pipe (SIPP) lining material that boasts structural characteristics. This material is a spray applied two component polyurethane high build coating. Three forms of sample were investigated during these tests: (1) No Fiber-Baseline (2) Rigid-with one layer of carbon fiber (3) Rigid—with two layers of carbon fiber. Three types of tests are performed: tensile, flexural, and hardness tests. This study included both experimental and Finite Element Analysis (FEA). Target mechanical properties of proposed material can be improved by using carbon fiber (CF) as reinforcement and based on the results of this study, the SIPP lining material with two layers of CF reinforcement has the highest value of 8,067 psi and 16,534 psi during the tensile and flexural test, respectively.

Gravity flow wastewater collection systems are comprised of sewer pipes and manholes. Failure of a manhole may have catastrophic consequences such as developing a sinkhole in the street and roadway, and at a minimum, wastewater flow will be blocked, and stream of the manhole will backup causing a sanitary sewer overflow (SSO). Improving structural conditions of a manhole is critical to minimize these types of failures. This paper considers the impact of several lining materials including cement mortar, epoxy, polyurethane, cured-in-place composites, and a multi-layer structure material on increasing the structural capabilities of deteriorated manholes. The tasks included in this research consist literature search and, preliminary laboratory and main testing of select manhole rehabilitation materials. A finite element analysis is included to complement the experiments. Several preliminary tests according to ASTM C-39 on coated concrete cylinders, and ASTM C-293 on lined concrete beams, were performed at UT Arlington's Center for Underground Infrastructure Research and Education (CUIRE) Laboratory. The test results showed significant increase in the performance of concrete samples under compression and flexure. A second round of testing was performed on 4-ft long, 24-in. diameter concrete pipe sections with 3-in. wall thickness manufactured according to ASTM C-76. These pipe sections were lined internally with the same materials as the preliminary tests, and tested according to ASTM C-497 under Three-Edge-Bearing testing. Using computer data acquisition system, strain gages and displacement extensometers, stress/strain data were measured. The results showed that tested No-Dig manhole rehabilitation materials can significantly improve structural performance of deteriorated manholes.

Horizontal Directional Drilling (HDD) technology is a highly complex process connected with high risk and uncertainty due the high variability underground strata, often limited access to specialised equipment, dynamic natural environment, technical disruptions, human factor and changes in economic environment that further complicate the gathering of reliable information and data. This work presents a new risk evaluation model tailored for HDD technology, in which failure mode and effect analysis (FMEA) modelling were applied. This paper focuses on 15 human risk factors and 9 equipment risk factors in HDD technology. The proposed approach takes into account not only the probability of the risk factor occurrence, but also its severity and the possibility of detecting faults, which were not clearly separated and analyzed in the previous works. Application of the proposed model shows the relationship between occurrence, severity and detection for the analyzed failures. Moreover, many detection possibilities for the identified failures were presented. The calculated risk priority numbers allowed to rank HDD failures and identify the most critical risks for which one should look for risk treatment possibilities beyond risk cause reduction, such as risk effect reduction, risk transfer, risk elimination or active risk retention. [ABSTRACT FROM AUTHOR]

Currently, we can observe an intensive development of underground infrastructure in cities around the world. This paper discusses the principles of risk management in underground construction of urban infrastructure. The author also presents own risk management methodology for trenchless constructions of pipelines applying various technologies. The risk management process in underground construction of urban utilities has been divided into five stages: risk assessment, selection of the risk treatment, risk register, risk monitoring and financing. Three selected, representative cases of the application of various risk management strategies in underground constructions have also been analysed. The analysis has shown that the introduction of the risk management strategy proposed by the author significantly increased the probability of completing the investment with a positive result, allowing to avoid emergency situations and to prevent adverse economic and legal consequences. In case of the two analysed investments, in which no consistent and effective risk management methodology was applied, undesirable unwanted events occurred, which resulted in serious economic and legal consequences. [ABSTRACT FROM AUTHOR]

The development of healable polymers is crucial for the maintenance of underground pipeline systems during trenchless rehabilitation. While photocurable resins are commercial materials for this purpose, we introduce an innovative option: azobenzene-containing polymers (azopolymers) with photoinduced reversible solid-to-liquid transitions. The newly developed azopolymer comprises a methacrylate backbone and side chains incorporating hexyl spacers, azobenzene moieties, and dodecyl tails. We compared the thermal stability, efficiency of photoinduced solid-to-liquid transition, and adhesive strength among azopolymers with varying molecular weights. Subsequently, we identified the most suitable azopolymer for PVC pipe lining. The robust trans azopolymer inner layer maintains a solid state at ambient temperatures. Upon pipe damage, UV irradiation triggers trans -to- cis isomerization, leading to the conversion of the solid trans azopolymer into a liquid cis state. This flowing cis azopolymer effectively repairs cracks and can be reverted to its trans isomer via visible light irradiation or thermal relaxation. Unlike commercial photocurable resins, the developed azopolymers offer the advantage of multiple repair cycles. This study highlights the potential of azopolymers with photoinduced reversible solid-to-liquid transitions as innovative healable materials in trenchless rehabilitation technology. [Display omitted] • Introducing azopolymers for trenchless pipeline repair. • Comparing efficiency of photoinduced solid-to-liquid transition in azopolymers. • Azopolymers allow unique, repeated in situ photoinduced repairs. [ABSTRACT FROM AUTHOR]

• The proposed design model guides the selection of required liner thicknesses. • Bending moments induced by earth loading govern liner design. • Nonlinear response of concrete may influence design. • Numerical models updated with nonlinear concrete and soil response. Buried reinforced concrete pipes (including sewers, stormwater pipes and other gravity flow structures) that experience unsafe levels of deterioration are commonly rehabilitated using trenchless solutions, such as the application of cementitious liners. Cementitious liners are centrifugally cast onto the inner surface of the damaged pipes with a spinning head that travels along the length of the pipe. Once cured, the liner increases the strength of the damaged pipe to resist applied earth and surface loads. A design method previously proposed by the authors provides guidance for selecting the required liner thickness to rehabilitate deteriorated concrete pipes situated at deep burials. However, this design method considers the linear elastic behaviour of the soil and pipe materials. Neglecting the nonlinear effects of crushing concrete within the host pipe may impact the predicted liner thicknesses for repair. Thus, the current study evaluates the impact of incorporating nonlinear compressive material behaviour on the required liner thicknesses to repair damaged concrete pipes. The required liner thicknesses obtained from the nonlinear version of the design method for rehabilitations of several pipes selected from the ASTM C76-11 Standard experiencing varying levels of deterioration are compared to thicknesses obtained using the authors' linear elastic solutions. The comparisons indicated that considering the nonlinear material response of the concrete generates slightly larger estimates of required liner thickness. The discrepancies between the estimated liner thicknesses were observed to be insignificant for pipes experiencing cracking and losses of concrete cover, demonstrating that the linear elastic model is suitable for design purposes. However, for damaged pipes situated at deep burials experiencing losses of tensile reinforcement, the discrepancies between the liner and nonlinear calculations become more significant. It is recommended that the results of the linear elastic model be checked with the nonlinear model for the repair of pipes experiencing loss of tensile reinforcement, or for deeply buried pipes. [ABSTRACT FROM AUTHOR]

Purpose. Building of new railway tracks and facilities, repair and replacement of existent underground utilities and communications is related to the receipt of horizontal cavities in soil by trenchless method. A static soil broaching with a working body with cone tip is the most widespread method in practice of forming a pilot hole at the trenchless laying of distributive communications. However, in the process of implementation of project calculations, receipt of pilot hole and subsequent expansion to the necessary sizes, there is a question of workings effort calculation methods. Existent methods are based on empiric dependences and experimental coefficients which diminish exactness of calculations and increase the cost of works. Methodology. The work proposes the dependence for determination of equivalent diameter of cone tip depending on the hole diameter and theoretical method for calculation of optimum parameters of soil broaching head using the well-known parameters: type of soil and its humidity, that determined by the State Construction Regulations (DBN). Findings. The results of the theoretical studies can be used to increase the efficiency of the working equipment for soil broaching by static method during trenchless laying of underground utilities and communications. Originality. The authors establish the dependence of the equivalent diameter of the cone base on the diameter of the cylindrical part of the broaching head, which allows for removal of the frictional force from the static broaching on the lateral cylindrical surface of the tip. Practical value. The obtained theoretical calculations for determining the optimal diameters of the cone tip with soil broaching spurs made it possible to establish that if thediameteroftheconeisgreaterthanthemaximumdiameterofthehole (soilcavity), thenthefrontalresistanceofthecone-cylindertipincreasesmoreintensivelythantheresistanceofthecylindricalpartofthetip. The maximum reduction in the broaching force takes place for a soil cavity whose diameter is 2 times smaller than the maximum limit diameter. When conducting the calculations regarding the choice of the size of working bodies for soil broaching, the source data include the type of soil, and its characteristics by DBN, as well as the moisture content of the soil determined by traditional methods.

C‐factor analysis helps a Canadian water utility target trenchless pipe lining repair for cost‐effective asset renewal. [ABSTRACT FROM AUTHOR]

An environmental impact assessment (EIA) involves the evaluation of information about pipe raw materials, processes, and product manufacturing to obtain the associated emissions and ecological impacts. Open-cut (OC) pipeline replacement involves digging a trench along the length of the proposed pipeline, placing the pipe in the trench on suitable bedding materials, and then embedding and backfilling. The trenchless cured-in-place pipe (CIPP) method involves a liquid thermoset resin saturated material that is inserted into the existing pipeline by hydrostatic or air inversion or by mechanically pulling-in and inflating. The liner material is cured-in-place using hot water or steam or light cured using ultraviolet light, resulting in the CIPP product. The objectives of this paper are: (1) to present a literature review on the progress acquired over the years in understanding the environmental impacts from the OC and CIPP methods, (2) to analyze and compare the environmental impacts for small diameter sanitary sewers (SDSS) using USEPA’s tool for the reduction and assessment of chemical and other environmental impacts (TRACI) methodology from the SimaPro software, and (3) to identify the factors that influence the environment for the OC and CIPP methods. Published papers were identified that reported the environmental impacts from the OC and CIPP methods over a period from 1989 through to 2020. An actual case study based on the City of Pasadena, California, river basin was used to carry out an environmental analysis for small diameter OC and CIPP methods. The literature review suggests that the material production phase consumes a large amount of energy and is a major contributor of environmental impacts. Higher environmental impacts from the OC method are a result of longer project durations and more equipment requirements compared to the CIPP. The assessment results show that, on average, CIPP renewal caused 68% less environmental impact, 75% less impact on human health, and 62% less resource depletion as compared to the OC replacement for SDSS. The liner, felt, and resin influenced the environment the most for CIPP as compared to the OC method, where the power consumption of construction equipment and the pipe material had the greatest environmental impacts. It can be concluded that the comparison of the environmental impacts from pipeline renewal and replacement is an important element when considering a sustainable underground infrastructure development. The pipe material and outside diameter should be considered during the installation phase by OC and CIPP methods to allow a detailed evaluation and comparison of their sustainability impacts. This study can be further developed for analyzing the environmental impacts and associated costs of the OC and CIPP methods for sanitary sewers with different project and site conditions.

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Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

When pipe laying in a clay or sandy stratum by Horizontal Directional Drilling (HDD), instability issues in the borehole wall are common due to low cohesion. Not only can such instability lead to the collapse of the upper ground and the destruction of the adjacent structures on the ground, but it can also cause drilling fluid overflows. In this paper, the authors proposed another additive using in horizontal directional drilling to prevent ground surface movement and drilling fluid overflowing. Based on the comparable method, the variety tests including bentonite yield, core dispersion test, expansion rate test, shear strength test, microstructures of mud cake, and rheological properties were performed between the ordinary drilling fluid and ENI solutions. The test results indicate that ENI solutions can provide enough positively cations such as Al 3+ to decrease the cation exchange activities and keep surrounding soil stability in the borehole. As a result, comparing to the ordinary drilling fluid, the rate of bentonite yield in ENI aqueous solution is decreased by about 50%. In addition, ENI solutions will product complex materials to fill the space between the soil particles to prevent fluid intrusion in the borehole. The shear strength test indicates that appropriate concentration of ENI can enhance the mechanical strength of the surrounding soil in the borehole. Then it can provide sufficient strength to balance the fluid pressure in horizontal directional drilling. At the same time, ENI can create a modified microstructure in the layers, so that the connecting force between particles is enhanced, and then the surrounding soil stability can also be improved. ENI also can keep the rheological properties of the drilling fluid system constant to meet requirements in the fieldwork. [ABSTRACT FROM AUTHOR]

One of the major challenges faced by water companies around the world is the high level of water losses in distribution networks. This research paper presents a case study on the choice of the best technical solution for the rehabilitation of the water distribution network pipelines of Cluj-Napoca City, Romania. The analytical network process (ANP) method was used as the selection method, and calculations were performed using the Super Decisions 2.6.0 software. In the case study, five alternatives were analyzed based on seven criteria. The criteria taken into account in the decision-making included pipe diameter, pipe length, specific accomplishment duration, lifespan, pressure losses, price, and installation conditions, while the following methods were considered as rehabilitation alternatives: Compact Pipe, Slipline, Subline, Swagelining, and Pilot Pipe. Based on the highest global priority, we recommend choosing the Subline alternative as the method of rehabilitating water distribution pipes from asbestos cement pipes in the case of Cluj-Napoca City, Romania. [ABSTRACT FROM AUTHOR]

There are many tools, models, and algorithms to aid in the selection of appropriate trenchless methods for pipeline installation or rehabilitation. However, one key concern is which method or technique provides optimum solution to the rehabilitation of multiple pipe segments rather than just a single pipe segment. Therefore, the searching criterion for an optimum decision support system is divided into two parts. First, the selection of the optimum method capable of solving the problem properly. Second, a simultaneous analysis of other parameters such as cost, time, and quality to improve the overall benefits of the project. It is observed that most of the real-world cases involves multiple segments in a single project. Therefore, an optimization of the solution must be made for those multiple pipe segments. Although use of different methods for each segment is a preferable solution, it may not be feasible in a wider consideration of project cost, quality, and time. Hence, one way to determine the optimal solution for multiple line segments is to minimize the number of methods and their anticipated total costs which include direct costs and social costs. This paper presents a mathematical approach to expedite the optimum solution by evaluating all of the trenchless technology methods capable of installing, replacing, or rehabilitating each pipe segment (a solution set) and minimizing the number of methods and their total costs. [ABSTRACT FROM AUTHOR]

The substandard condition of wastewater systems in the US, accompanied by the lack of financial resources for renewal are hindering adequate operation and maintenance of deficient sewer systems. Information about current and future pipe condition, as well as information about the impact of possible pipe failures are an integral part of an efficient asset management program and can help stakeholders make the best decisions to prioritize rehabilitation and/or replacement projects. Typically, pipes in the worst structural conditions are prioritized and budgeted within the capital improvement project planning. To be able to predict future pipe conditions, many methods have been developed and successfully implemented that incorporate pipe inspection data to predict the future state of these assets. Additionally, methodologies exist for determining the consequences of pipe failures economically, socially, and environmentally. These methods have been incorporated into decision support systems (DSS) that help utility managers determine when to rehabilitate or replace their assets. DSS for trenchless pipe renewal allow utility managers to determine the most suitable method to renew their assets, given known defects in the pipe. The aim of this paper is to provide a review of risk management methods that allow pipeline managers to estimate likelihood of failure and quantify consequence of failure of sewer pipes. Additionally, an updated review of existing DSS for trenchless pipe rehabilitation is presented and analyzed. Finally, recommendations are made to improve existing methods to make the risk management process for trenchless rehabilitation decision making more efficient and practical. [ABSTRACT FROM AUTHOR]

Microtunneling is a complex trenchless excavation process. Efficient microtunneling methods is necessary to identify risk level problems that often require the integration of supporting equipment and personnel. A clearer understanding of risk level problems will facilitate the enhancement and modeling of risk assessments for future microtunneling projects. This study investigates 12 different factors to assess risk level problems in microtunneling projects. The factors and factors' weight are collected using a questionnaire sent to microtunneling-industry specialists. A risk level prediction model is developed using the clustering analysis technique and the analytical hierarchy process to consider the qualitative factors involved in the microtunneling process. The model is then validated, which shows reasonable results with 89% average validity percent. The main objective of the developed model is to assist contractors in the bidding and operation phases of microtunneling projects by providing reasonably accurate mitigation models. [ABSTRACT FROM AUTHOR]