Trenchless Methods Research Articles

Experimental Study on Quick‐Locking Reinforcement Model for Local Defects in Pipelines in the Rich Water Area

ABSTRACTThe management of local defects in municipal pipelines in water‐rich areas remains a significant challenge, particularly under high‐pressure conditions. This study investigates the performance of quick‐lock steel sleeves as a trenchless repair method through full‐scale experiments on five different pipeline diameters. The experiments focus on the failure modes and critical buckling pressure of the sleeves under external pressure. A novel design model based on structural reliability theory was developed and validated against experimental results. The results show a close match between the calculated and experimental buckling pressures, with a ratio ranging from 0.87 to 1.15. These findings provide valuable insights for the design and application of quick‐lock sleeves in high‐pressure municipal networks. This study contributes to improving the reliability and effectiveness of pipeline repair technologies, offering practical solutions for addressing pipeline leakage and instability in challenging environments.

Pushing boundaries in slurry microtunneling: Innovations in microtunnel boring machine design for hard rock conditions

AbstractFor microtunneling in hard rock, as it is encountered very often in alpine tunneling, the continuous further development of technologies plays a key role to overcome the limitations in drive length and to improve performance. During the last decades, the application range of slurry microtunneling has been considerably extended and more demanding projects have been designed for underground utilities installations worldwide, including many sewage tunnels and hydropower plants. The prevailing ground conditions still play a key role and determine the limits for alignment design and the possible use of trenchless construction methods. In hard rock conditions with high rock strength and/or abrasivity, the applicability of slurry microtunneling has been especially limited in the non‐accessible diameter range in the past. With the new AVN 800 HR for hard rock microtunneling, Herrenknecht has developed a machine concept, enabling drives of up to 200 m, with precise steering of the MTBM. Longer drives, even through hard rock, make microtunneling a more economic, flexible, and more environmentally friendly construction method. New opportunities for clients and consultants in the planning of tunnel routes in alpine environments for different infrastructure installations can be considered, making trenchless installations even more cost‐effective, while improving public acceptance.

Development of die drawing design factor prediction models for trenchless rehabilitation of water pipes: a case study

ABSTRACT Maintenance and replacement of aging water pipes are critical for urban development. To this end, trenchless rehabilitation methods that do not require excavation offer an efficient replacement for aging water pipes. Thus, this study developed a trenchless method using die drawing, which continuously inserts polyethylene (PE) liners into the reach point while maintaining traction in the host aging pipe. If the traction is removed after a certain period, the initially contracted liner pipe undergoes expansion under natural restoration and tightly adheres to the inner wall of the host pipe to achieve structural regeneration of the aging pipe. This study aimed to determine the factors influencing the die drawing process using a rehabilitation design. Accordingly, we experimented with the die drawing method to achieve structural reinforcement using high elasticity PE liners. Thereafter, based on the experimental data, we developed prediction models to estimate traction, pipe restoration rate after traction release, and pipe restoration period. The developed models estimated the minimum required restoration period and provided deeper insights into the restoration behavior of the die drawing method employed in pre-equipment maintenance before on-site construction.

Large rectangular cross-section tunnel undercrossing urban road by micro pipe jacking and joint assembly structure (MPJ & JAS) method in soft soils

With the continuous construction of urban traffic roads, more and more new roads are cut off by existing roads to form “dead end roads”. There is an urgent need for a trenchless method suitable for urban ultra-shallow overburden to build the undercrossing tunnel. To solve this problem, this paper proposed the micro pipe jacking and joint assembly structure (MPJ & JAS) method, which has the characteristics of shallow burial depth, low cost, short construction time, flexible cross-section setting and high space utilization. The MPJ & JAS method construct a large cross-section tunnel through assembling small cross-section elements, quite different from traditional methods. Therefore, this paper designed a CT-shaped integrated joint, the mechanical performance of which was verified and clarified by tensile test. The bending test and finite element (FE) analysis proved the reliability of MPJ & JAS tunnel structure, and confirmed the structure performances such as the failure models, crack behaviors, load–deflection response and stress–strain distribution. Moreover, the influences of the steel plate thickness, concrete strength and shear connector spacing were determined by the FE analysis. On the basis of test results and reasonable assumptions, a theoretical design method considering the influence of the CT-shaped integrated joint was proposed, which can effectively predict the bending strength of the MPJ & JAS tunnel structure with an error of less than 10%. Finally, in view of the characteristics of the MPJ & JAS method, the suitable micro pipe jacking machine, soil reinforcement measure, hydraulic traction construction technology, high-precision guidance system and concrete construction quality detection method based on the phased array ultrasonic imaging technology were developed, supporting the accurate and efficient construction of the MPJ & JAS tunnel.

Comparative research on the pipe-soil frictional resistances of circular and rectangular pipe sections during trenchless pipe jacking.

Pipe jacking is a trenchless construction method to achieve forward tunneling and efficient construction of underground structure simultaneously without extensive surface excavation. In the process of pipe jacking construction, the jacking force provided by the hydraulic jacking equipment must overcome the frontal resistance of the cutter head and the frictional resistance between the pipe sections and formation at the same time. In particular, the pipe-soil frictional resistance increases with the increases of jacking distance, buried depth, pipe diameter and the complexity of jacking trajectory. Therefore, it is very important to correctly estimate jacking force in trenchless jacking engineering practice for the smooth implementation of pipe jacking, operation risk and comprehensive cost control. Firstly, the stress states of jacking circular and rectangular pipe sections in the soil are analyzed, and the key influencing factors of their pipe-soil frictional resistance are obtained respectively. Then, the pipe-soil frictional resistance of jacking the circular and rectangular pipe sections with the same external surface area in the dry sandy soil and coal granular layer are tested separately by using the self-developed multifunctional experimental apparatus during trenchless pipe jacking. The results show that the pipe-soil frictional resistances of jacking circular and rectangular pipe sections in the coal granular layer are always smaller than that in the sandy soil under the same experimental conditions, and the corresponding fitting calculation equation of pipe-soil frictional resistances are obtained respectively. Meanwhile, the modified calculation methods of the above pipe-soil frictional resistances are proposed respectively based on the relationship between the lateral pressure coefficient K and the buried depth of pipe section H. Moreover, the disturbed area of soil in the upper part of jacking circular pipe section presents an arc distribution, while the disturbed area of soil in the upper part of jacking rectangular pipe section presents a slightly concave distribution. Due to the different disturbance conditions of soil around the pipe section, the lateral pressure coefficient K should be corrected in the calculation equations of pipe-soil frictional resistance of jacking circular and rectangular pipe sections based on the discrete element numerical simulation analysis by EDEM software. Finally, the pipe-soil frictional resistances obtained by different methods in the sandy soil are compared and analyzed. The calculated values of the modified theoretical calculation method are very close to the experimental test values, while the other methods are smaller than the experimental test values, which makes the rationality of the modified theoretical calculation method of pipe-soil frictional resistance is verified, and some suggestions are also put forward for the value of some coefficients in the relevant empirical estimation equations. The above research achievements systematically compared the states of pipe-soil frictional resistances of jacking circular and rectangular pipe sections based on different research methods, especially for the correct evaluation of jacking force during trenchless pipe jacking, they could provide some valuable references and effective guidance for the subsequent research, engineering practice and further development of trenchless pipe jacking technology.

Low-carbon effects of constructing a prefabricated subway station using a trenchless method: A case study in Shenzhen, China

The traditional open-cut construction method for subway stations poses significant social and environmental challenges, and a trenchless method represents a promising alternative. This study uses the construction of a subway station in Shenzhen using a trenchless pipe-jacking method, as a case study. The design concept and construction scheme of the station are presented in detail, and the technical benefits of the technology are analysed. To assess the low-carbon effects of the method, this study uses life cycle assessment (LCA) theory. The findings indicate that the greenhouse gas (GHG) emissions of the station constructed this way are 10.5% less than those of the open-cut cast-in-situ (CIS) method. This decrease is attributable to reduced GHG emissions of 9.39% and 20.14% from building materials and related to energy consumption, respectively, achieved by reducing material consumption and improving electrification. Soil reinforcement engineering at the launching and receiving shafts is a significant factor affecting 34.17 % of the GHG emissions of the trenchless method, primarily owing to the significant cement consumption. The trenchless construction method used for the middle part of the station, which is beneath a large box culvert section, can decrease GHG emissions by 52.66% compared with open-cut CIS schemes. This is due mainly to the avoidance of additional GHG emissions resulting from the relocation of large box culverts required before open-cut construction of the station. Trenchless method, therefore, offers many advantages in reducing emissions and generating social benefits in complex urban environments compared with open-cut method, making it an essential approach to assist sustainable underground space development.

Non-Destructive Characterization of Cured-in-Place Pipe Defects.

Sewage and water networks are crucial infrastructures of modern urban society. The uninterrupted functionality of these networks is paramount, necessitating regular maintenance and rehabilitation. In densely populated urban areas, trenchless methods, particularly those employing cured-in-place pipe technology, have emerged as the most cost-efficient approach for network rehabilitation. Common diagnostic methods for assessing pipe conditions, whether original or retrofitted with-cured-in-place pipes, typically include camera examination or laser scans, and are limited in material characterization. This study introduces three innovative methods for characterizing critical aspects of pipe conditions. The impact-echo method, ground-penetrating radar, and impedance spectroscopy address the challenges posed by polymer liners and offer enhanced accuracy in defect detection. These methods enable the characterization of delamination, identification of caverns behind cured-in-place pipes, and evaluation of overall pipe health. A machine learning algorithm using deep learning on images acquired from impact-echo signals using continuous wavelet transformation is presented to characterize defects. The aim is to compare traditional machine learning and deep learning methods to characterize selected pipe defects. The measurement conducted with ground-penetrating radar is depicted, employing a heuristic algorithm to estimate caverns behind the tested polymer composites. This study also presents results obtained through impedance spectroscopy, employed to characterize the delamination of polymer liners caused by uneven curing. A comparative analysis of these methods is conducted, assessing the accuracy by comparing the known positions of defects with their predicted characteristics based on laboratory measurements.

Energy efficiency of “hot” oil pipelines under partial load conditions

The article discusses trenchless methods of pipeline repair, which can be used in the repair of oil pipelines in conditions of incomplete loading. Trenchless pipeline reconstruction technologies are widely used due to certain advantages that ensure environmental safety and economic efficiency. Such technologies can be used in conditions where it is impossible to use open methods of repair, with minimal volumes of earthworks, without damage to existing underground communications, as well as when working in unstable soil conditions. The main attention is paid to the repair according to the “pipe in a pipe without destruction” scheme. The article is devoted to solving the optimization problem of choosing the diameter and wall thickness of the internal pipeline, which runs in the repaired one, according to the criteria of minimal heat loss at maximum throughput, in which energy costs for transporting the product will be minimal, which will allow obtaining maximum energy efficiency. The authors use analytical methods and conduct a study of the influence of changes in pipeline characteristics on product pumping parameters. The results of the study show that the methods of trenchless repair of “hot” oil pipelines are effective from an economic and energy point of view. The work established that during the repair of long “hot” oil pipelines with intermediate heating points, the selection of the diameter of the internal pipeline requires taking into account the energy consumption at these intermediate heating points. The work contains an algorithm for choosing the optimal diameter and wall thickness of the pipeline, which can be useful for oil transportation enterprises and energy companies to optimize work and reduce energy costs for transporting the product

DGM-MDS: Dynamic grouting monitoring with a novel multi-channel distributed system

With the development of engineering construction, the construction of underground space with complex geological structures is increasing, resulting in more potential engineering problems (e.g., water inrush). Grouting, as a technology for prevention and control, has been widely used in engineering applications such as tunnel construction and pile foundation engineering. To the best of our knowledge, a trenchless visualization method, which can effectively control and evaluate grouting fluid filling of underground space for energy saving, environmental protection and reliable construction quality, is underexplored today. To this end, a novel distributed wireless sensor network-based solution is proposed in this paper. Specifically, metal electrodes are first inserted into the ground in the grouting area to collect data from underground space during the grouting process. Then, by leveraging resistivity inversion imaging software, an effective dynamic monitoring can be achieved so that the grouting effect can be evaluated accurately by observing the grouting diffusion, filling range and evolution process in the underground. Finally, the proposed distributed system can collect multiple profile data in quasi real-time by flexible wireless networking mode, leading to comprehensive and effective monitoring of underground filling for grouting engineering. Experiments on lossy clay area show the effectiveness of our proposed distributed system for engineering monitoring in the field of grouting.

Зависимость гидравлических характеристик самотечных канализационных трубопроводов от способа проведения их бестраншейного ремонта

Purpose: When reconstructing gravity sewer networks laid in urban and rural environments, various technologies can be used. Trenchless repairs, which are actively used in a built-up area, subsequently affect the capacity of networks, while the hydraulic characteristics of the flow depend on the accepted technology of work. Assessment of hydraulic characteristics of gravity sewer pipelines depending on the chosen method of carrying out their trenchless repair is the purpose of the study. Methods: Analytical determination of hydraulic flow characteristics in gravity pipelines after their repair by various trenchless methods and comparison of the results obtained. Results: The analysis of the obtained results shows that after reconstruction in various ways, the hydraulic parameters of the pipelines may change and not meet regulatory requirements. The necessity of carrying out analytical calculations at the stage of choosing a method for trenchless repair of gravity sewer networks is shown. Practical significance: The results of the work are recommended to be taken into account when choosing trenchless technologies for repairing gravity sewer pipelines.

Transition of the pipe jacking technology in Japan and investigation of its application status

Pipe-jacking is one of the trenchless methods being widely used for the construction and maintenance of urban underground pipelines. As an eco-friendly construction method, it has the capacity for the installation of pipelines with diameters from 100 mm (4 in.) to 5000 mm (200 in.) covering the majority needs of municipal pipeline construction and is considered the most widely used trenchless method in Japan. However, there is little English literature that systematically introduces the research and application status of pipe jacking technology in Japan, resulting in a serious underestimation ofJapanese research achievements in this field. This paper briefly reviews the origin, evolutionary stages, and classification system of the pipe jacking method in Japan, and representative technological advances are also introduced through case statistics. Meanwhile, the deficiencies in the current classification system of the International Society of Trenchless Technology (ISTT) are discussed as well. In addition, the application status of this method is investigated based on survey data from the Japan Society for Trenchless Technology (JSTT). According to the survey data from 5232 projects, a systematic analysis is carried out on the selection of pipe jacking equipment, the scale of jacking construction, the profile of curved projects, and the geological adaptability of the pipe jacking method in Japan. The emphasis of this paper is to introduce the current technical situation and analyze the development trends of the pipe-jacking method based on Japan's experience, and to popularize this method in other countries that need this simple,effective, andeconomical construction technique under the background of climate change.

Numerical study on mechanical properties of pipeline installed via horizontal directional drilling under static and dynamic traffic loads

The present study investigates the mechanical behavior of pipes installed via horizontal directional drilling method, a typical trenchless method for highway-crossing pipeline installation, under traffic loads. The effects of both stationary and moving vehicles are considered in the analysis. Results from the static analysis indicate that the pipe experiences maximum stress at its top, with minimum stress at its bottom. Furthermore, the stress change in soil is more significant than that in the pipeline as the vehicle weight increases. When a moving vehicle passes over the pipeline, the stress of the pipeline remains relatively constant. No significant change in pipe stress is observed with changes in vehicle weight and speed. However, when the vehicle speed approaches 100 km/h, the maximum soil stress decreases significantly. Conversely, the pipe stress is higher when the vehicle is stationary compared to when it is moving. A comparison is made between the mechanical behavior of pipes installed via horizontal directional drilling and open-cut methods under traffic loads, with the results revealing that the stress of pipelines installed via horizontal directional drilling method is higher than those installed via open-cut method in both static and dynamic analyses. Nonetheless, the stress variation amplitude of pipelines installed via horizontal directional drilling method is smaller during vehicular passage, thus indicating a lower possibility of fatigue failure caused by traffic loads.

Hydraulic characteristics of pipelines restored using polymer hoses

Aging water supply and wastewater pipeline systems suffer from corrosion and damage. Trenchless restoration methods extend their lifespan and reduce repairing costs. However, there is no standard method for determining the hydraulic characteristics of restored pipelines, making it challenging to assess the feasibility of using different materials for restoration. This article focuses on changes in hydraulic characteristics after restoring pipelines with glass fiber and synthetic felt hoses. The study uses Bernoulli’s equation and the Chezy formula to estimate changes in the flow capacity of pipelines. Standard values for slopes, flow rates, and filling rates were used to calculate the hydraulic resistance coefficient, Chezy coefficient, and flow rate after laying polymer hoses. The results show that the flow capacity of restored pipelines increases, and there is no need for further hydraulic calculations to confirm the absence of a reduction in pipeline capacity after restoration. Therefore, trenchless restoration methods can be considered as effective means to extend the lifespan of aging pipeline systems and reduce engineering repairs costs.

Design of Municipal Sewer Pipe Jacking under Complex Geological Conditions in Plateau Regions

The drainage and sewage interception project hi Zhaoyang District involved the installation of a DN1000 municipal sewer pipeline with a total length of 1541 m. Considering factors such as geological conditions, pipe diameter, buried depth, groundwater level, as well as the impact of nearby underground and aboveground structures and traffic, the trenchless construction method of pipe jacking was selected for implementation. The pipeline followed the route of Weiba Road, crossed Jinying Avenue, and then proceeded along the Second Ring East Road until it reached the bank of Yaowan River. The project design took into account practical considerations, including the sewer pipe diameter, material selection, pipeline routing, construction of pipe jacking starting shafts, and the design and modification of arriving shafts, in line with the specific engineering requirements.

Approaches to the automated design of restoration work on dilapidated gravity pipeline networks in the presence of foul-smelling gases in them

The article considers the problems of improving the efficiency of design, construction, and reconstruction of gravity-flow pipeline networks based on computer modeling, as well as automation of estimated calculations, considering the use of modern trenchless technologies. The authors present the solution to a problem of a choice of the optimum variant of repair from among alternatives at the reconstruction of a dilapidated pipeline from chrysotile cement of the corresponding diameter and extent in which underlying space there is a foul-smelling and aggressive gas (hydrogen sulfide) in the quantity considerably exceeding its maximum permissible concentration in the atmosphere of cities. Computer modeling considered maximum permissible concentrations of harmful gas emissions and values according to data from organizations operating the network. The results of the work of the automated complex are temporal characteristics of removal of gas components at the organization of artificial air exchange in the under-flowing space of the gravity pipeline at the expense of the selection of productivity of ventilation units. We estimated the cost parameters of preparatory, basic, and finishing construction-technological operations in the complex of works on estimating repair-construction works. For example, mechanical cleaning of the inner surface of the drainage pipeline, organization of dewatering in case of groundwater level above the pipeline, and television inspection of the pipeline after the restoration operation by alternative trenchless methods.

Influence of Physical and Chemical Stress on the Properties of CIPP Pipes Based on Vinyl Ester

Cured-in-place pipe (CIPP) is one of the trenchless sewer rehabilitation methods for repairing sewer pipe using different types of resin, curing technology and reinforced polymer fiber. In the research described in this article, the chemical and temperature resistance of CIPP pipes based on vinyl ester resin, cured with hot water, were tested. The specimens of the CIPP pipes were exposed to a chemically aggressive environment and an elevated temperature, namely 20% sulfuric acid (pH = 1) and a temperature of 50°C. The samples were tested every month for short-term flexural properties as well as hardness. Changes of the flexural properties and hardness were compared with reference samples that were stored under laboratory conditions (23±0,5°C, relative humidity 50% ±10%). It was found out that the applied aggressive environment does not have a negative impact on the mechanical properties of the CIPP pipes based on vinyl ester resin even after long-term exposure. Furthermore, the influence of the aggressive environment on the microstructure of CIPP samples was monitored by digital optical microscopy.

Surface settlement induced by horizontal directional drilling

Horizontal directional drilling (HDD) is a widely used trenchless method for underground utility connections. The associated ground settlement triggered by HDD depends on the size, types, and surface texture of pipe, diameter of borehole, and soil conditions. The present study investigates the surface settlement due to the construction of a 1067 mm diameter HDD, which will replace an existing sewer siphon under the SR-60 highway in Chino, California using empirical, and numerical methods. Based on the results obtained from the subsurface investigation, an empirical analysis was conducted first. followed by numerical modeling of the HDD using PLAXIS 2D software. A careful comparison between two different methods indicated closer values of surface settlement between the empirical method (7.3 mm) and the numerical modeling (4.6 mm). In addition, the shape of surface settlement and horizontal settlement curves for the empirical and numerical methods was found to be similar. The minor discrepancy between the two methods resulted as the numerical model can host several soil layers whereas the empirical equation can use only one type of soil. Finally, a parametric study was conducted to evaluate the effect of borehole cover depth, size, and soil parameters on surface settlement. It was observed that soil strength parameters yielded a greater effect on surface movement, whereas modulus of elasticity has a relatively smaller influence with zero contribution from Poisson's ratio.

A Comparative Review of Trenchless Cured-in-Place Pipe (CIPP) With Spray Applied Pipe Lining (SAPL) Renewal Methods for Pipelines

Pipes have been used for thousands of years, the first record of copper piping dates to the Egyptians in 3000 BC. In today's time, pipelines play a dramatic role in our everyday life and is a backbone of our society. Replacing and renewing our vast piping system is extremely important to maintain and grow the infrastructure around us. Trenchless methods (TM) can renew pre-existing piping, replace, and offer installation of new pipe(s). Two very common TMs are cured-in-place piping (CIPP) and spray-applied pipe lining (SAPL). These are great alternatives compared to open cut pipeline installation (OCPI) due to minimizing environmental impact and the total cost associated with renewing or replacing a pipe. Owners and engineers involved in a project which contain pipe renewal and or replacement should consider the time and social cost associated with each method. Cost alone should not be the one and only deciding factor. The objective of this review is to compare and contrast CIPP and SAPL pipeline renewal methods with references found over these renewal methods. This will be demonstrated with the use of a table that will consist of these parameters; environmental, mechanical properties, performance, cost, and methods. The method used for selecting specific articles/papers is intended to locate major factors that play a role in pipeline renewal using publications from the past years. Results show that reviewing, comparing, and understanding current research relating to pipeline renewal will allow for safer applications, increased efficiency, and pipeline longevity.

Major rebuilding and reconstruction of sewer networks in Samara

In Samara, capital rebuilding and reconstruction of sewer networks are carried out using modern trenchless methods of restoration (renovation) and rehabilitation of pipelines, as well as using the traditional method, which consists in replacing pipes in the repaired section of the pipeline network using an open trench mining method. A limited time is allotted to carry out work to eliminate an accident on the sewer network, therefore, the choice of technology for cleaning the pipeline and (or) its restoration (renovation) must be carried out promptly on the basis of pre-developed technological maps, taking into account information and documents from the information model of this section of the sewer network .

Case Study of Trenchless Technology Around The Globe

Abstract: Trenchless technology is the science of installing, repairing and renewing underground constructions, pipes, and cables that minimize the use of open-cut excavation methods. The use of traditional construction techniques, preferably open-cut construction are being used less because of innovation in trenchless methods. These methods reduce the impact on the environment i.e harmful gas and disruption i.e traffic delays, pedestrian problems, noise problems, and surface issues. This research will describe the advantages of trenchless methods over conventional trenching methods. Keywords: Trenchless technology, Open-cut excavation.