Pipe Jacking Project Research Articles

Prediction of Jacking Force for Construction of Long-Distance Rectangular Utility Tunnel Using Differential Evolution–Bidirectional Gated Re-Current Unit–Attention Model

Most of the current machine learning algorithms are applied to predict the jacking force required in micro-tunneling; in contrast, few studies about long-distance, large-section jacking projects have been reported in the literature. In this study, an intelligent framework, consisting of a differential evolution (DE), a bidirectional gated re-current unit (BiGRU), and attention mechanisms was developed to automatically identify the optimal hyperparameters and assign weights to the information features, as well as capture the bidirectional temporal features of sequential data. Based on field data from a pipe jacking project crossing underneath a canal, the model’s performance was compared with those of four conventional models (RNN, GRU, BiGRU, and DE–BiGRU). The results indicated that the DE–BiGRU–attention model performed best among these models. Then, the generalization performance of the proposed model in predicting jacking forces was evaluated with the aid of a similar case at the site. It was found that fine-tuning parameters for specific projects is essential for improving the model’s generalization performance. More generally, the proposed prediction model was found to be practically useful to professionals and engineers in making real-time adjustments to jacking parameters, predicting jacking force, and carrying out performance evaluations.

Numerical Simulation Study on Evolution Process of Carrying-Soil Effect of Rectangular Pipe Jacking

The carrying-soil effect is an important factor affecting the success or failure of rectangular pipe jacking construction. Because it is difficult to explore the dynamic evolution process of the carrying-soil effect in the field test, this paper relies on the pipe jacking project of a comprehensive pipe gallery in Suzhou City, and uses ABAQUS 2021 finite element software to simulate the jacking process of rectangular pipe jacking. Based on the theory of plastic mechanics of rock and soil and the related research and application status, the equivalent plastic strain index is introduced as the basis for judging the failure boundary of soil in the numerical simulation results, and the boundary between the carrying-soil area and the surrounding soil is determined, that is, the shear fracture surface. According to the principle of plastic potential energy, the development direction of the fracture surface is consistent with the direction of plastic flow, so as to predict the development direction of the boundary of the carrying-soil area. According to the change in the equivalent plastic strain cloud map with the jacking mileage, the evolution process of the carrying-soil effect is clarified, and the dynamic evolution law of the carrying-soil area is revealed, which is of great significance for predicting the disturbance of the surrounding soil during the construction of rectangular pipe jacking and accurately evaluating the environmental effect of the construction.

A Method for calculating jacking force of parallel pipes considering Soil Arching Effect and Pipe-Slurry-Soil Interaction

For multiple parallel pipe jacking projects, the calculation of the jacking force is crucial for design and construction. This paper presented a method for the calculation method of the jacking force required by each pipe, which includes the jacking resistance of the excavation face and the side friction around pipe. Firstly, the improved composite arch model in front of the excavation face was established under the limit support state, and jacking resistance of the excavation face was obtained by calculating the limit support pressure according to the model. Then, based on four typical pipe-slurry-soil contact modes, an improved calculation method for side friction was proposed and then corrected for multiple pipes under mutual disturbance. The reliability of the calculation method was subsequently proven by comparison with the model test results and engineering case data available in the literature. The mutual disturbance level among pipes decreases with increasing Poisson’s ratio of surrounding soil. Compared with a single pipe under the same conditions, pipe under the influence of mutual disturbance usually requires a larger force for jacking, so that the required jacking force of the following pipes in multiple parallel pipe jacking projects is usually larger than that of the initial pipe.

Research on construction and environmental impacts of a large-diameter pipe jacked along curve underwater

The pipe jacking method is widely used in water supply and drainage, power tunnels, vehicle tunnel construction, and other fields. The main challenges include friction resistance, axis deviation, and environmental disturbance, especially when large-diameter pipes are jacked along the curve underwater. Based on a large-diameter pipe jacking project under Jinshan Lake, this paper records the settlement of surrounding structures, the jacking force, and the deviation in the axis and elevation during the jacking process. Furthermore, the factors affecting the monitoring data under different working conditions are studied, and the key points are concluded. The outcomes of the study will provide a reference and serve as a guidance for future related projects.

Large-scale field test on the shear behavior of concrete pipe-silty soil interfaces in pipe jacking: A case study

With the rapid advancement of urbanization, research on the shear behavior of concrete pipe-silty soil interfaces in pipe jacking has a high engineering application value. In this study, a large-scale field direct shear test apparatus and the corresponding test method were designed and proposed to investigate the shear properties of the concrete-silty soil interfaces in pipe jacking. A series of in-situ direct shear tests were conducted at five normal stress levels under four interface contact conditions. The results show that the shear stress-displacement relationships of the interfaces conform to the typical elastic-plastic constitutive relations, the shear strength-normal stress relationships of the interfaces can be well fitted by the Mohr-Coulomb failure criterion, and the interface shear properties are influenced by soil properties, normal stress, lubrication conditions and stagnation time. Without lubrication, the concrete-silty soil interfaces have a shear stress-displacement curve shape similar to that of the test results obtained from indoor direct shear tests, but their ductility and shear strengths are lower. Under lubrication conditions, the paraffin wax and thixotropic slurry can both effectively diminish the interface friction angle, thereby reducing the concrete-silty clay interface friction coefficient by 62.8% and 72.2% and reducing the concrete-silty sand interface friction coefficient by 60.8% and 59.2%, respectively. Based on the macroscopic and microscopic images observed in the tests, the lubrication mechanisms of the lubricants were analysed. The research results can provide a reference for the prediction of jacking force and construction disturbance in adjacent pipe jacking projects.

Ground Settlement Law, Jacking Force Prediction, and Control Countermeasures for Large-Section Rectangular Pipe Jacking of National Highway Underpass

The rectangular pipe jacking method is an efficient, green, trenchless technology for constructing urban underground space. However, some problems, including the high jacking resistance, the instability of the tunneling face, and excessive ground settlement during the large-section rectangular pipe jacking for the underpass of national highways, seriously affect construction safety and traffic. Based on the engineering background of the large-section rectangular pipe jacking in constructing the subway entrance tunnel of Guangzhou Metro Line 7, this work adopts the methods of theoretical calculation, numerical simulation, and engineering application. Five kinds of mechanical models for pipe soil slurry interactions in rectangular pipe jacking are analyzed. An evaluation of the applicability of the jacking force prediction of the different models is conducted. Moreover, the ground settlement law for the large-section rectangular pipe jacking for the underpass of national highways under different influencing factors, including slurry sleeve thickness, grouting pressure, and earth chamber pressure, is revealed. The control countermeasures of the ground settlements, such as installing a waterproof rubber curtain for the tunnel portal, pipe jacking machine receiving techniques, thixotropic slurry for reducing friction resistance, and soil stability at the tunneling face, are carried out. The results show that there is no need to install an intermediate jacking station in the large-section rectangular pipe jacking project with a jacking distance of 63 m. The most reasonable thickness of the thixotropic slurry sleeve is about 150 mm. The most reasonable grouting pressure range is 600–700 kPa. An earth chamber pressure of about 153 kPa is more reasonable to control the soil stability of the tunneling face. The engineering practice shows that the maximum ground settlement of the national highway during jacking is 10 mm. The maintenance effect is excellent, and the traffic operates normally.

Study on the Division of the Affected Zone under Construction Unloading and Its Construction Sequence of the Multiline Parallel River-Crossing Pipe Jacking

There are many advantages of reasonably determining the affected zone and its construction sequence for the multiline parallel pipe-jacking construction, such as convenient to reasonably arrange the pipeline section distribution mode, reducing the construction safety risk, and construction difficulty. Combined with the engineering construction practice of the multiline parallel pipe-jacking project for the north city drainage and flood control project through Chu River in Hefei, the strength reduction method has been utilized to study the surrounding stratum FOS for the pipe-jacking construction unloading under different overburden thickness Hs, different clear distance D, and different river water depth H w in this paper. The formula of the minimum critical overburden thickness Hsmin and the minimum critical clear distance Dmin of the surrounding stratum self-stability during pipe-jacking construction unloading have been derived. The division method of the affected zone for the multiline parallel river-crossing pipe-jacking construction which behaves as the mutual influence nonself-stability zone, the mutual influence self-stability zone, and the no mutual influence self-stability zone has been proposed. For further discussion, the construction sequence of the multiline parallel river-crossing pipe jacking has been studied.

CASE STUDY ON THE LARGE DIAMETER PIPE JACKING FOR UTILITY TUNNEL

Pipe jacking have been widely used in utility tunnel constructions as an environment-friendly method in China. This study is focus on the critical technologies used in the pipe jacking for the utility tunnel in Huanggang Mingzhu road. The inner and outer diameter of this utility tunnel are 4m and 4.8m respectively, which is the largest circular pipe jacking project in China at present. This utility tunnel is designed under the urban main road with a heavy traffic, so the control accuracy of pipe jacking construction is required to be high. According to the characteristics of the project and actual construction technical measures, the key construction technologies including pipe jacking equipment, launching of small spacing, slurry circulating, the drag reduction technology, and the control of surface settlement are discussed in this paper. Meanwhile, the jacking force and ground settlement during pipe jacking construction are monitored. The results show that the selected pipe jacking machine has good adaptability to the geological conditions of the project. The actual jacking force is much smaller than the theoretical value, and the two intermediate jacking stations are not activated. In addition, the road surface deformation is -8–5mm during the whole process of pipe jacking construction, which has no impact on surface traffic.

Small‐diameter tunneling in difficult ground – Analysis of TBM performance in hard rock

AbstractSmall‐diameter tunneling in hard rock is increasingly widespread due to the need for new and longer utility tunnels comprising sewer, stormwater, freshwater, or hydropower as well as cable tunnels and casings for pipelines transporting gas or hydrogen. Utility tunnels have to deal with a wide range of geological settings, like small overburden, weathered rock, rock–soil transitions, as well as fractured or intact hard rock with high strength and abrasivity. A database has been created including 35 hard rock projects with diameters between 1 and 5 m as well as more than 70,000 m of tunnel alignments, with a median drive length of less than 500 m. Challenges in creating it and some early interpretations based on the contents of the database are presented. Details about an exemplary pipe jacking project in basement rocks in Brittany, France, are given. The large variety in this small‐diameter range in hard rock includes different TBM types, cutterhead designs, cutter types, and geotechnical conditions. Potential pitfalls in small‐diameter TBM data analysis are shown and general drive parameter trends and penetration prediction approaches are presented and set in relation to the geotechnical conditions. Our analysis shows that difficult ground conditions do not only incorporate rocks with very high strength, but also generally weak rocks like schist or limestone could be responsible for low penetration rates and high thrust forces.

Construction technologies and mechanical effects of the pipe-jacking crossing anchor-cable group in soft stratum

In this study, an open-cut approach using steel-sheet piles and jet grouting piles for waterproofing was proposed to resolve the problem that ordinary pipe-jacking equipment cannot cross areas with existing anchor cables in soft stratum. The case history of a pipe-jacking project of a sewage treatment plant in the Jinan East Railway Station area was investigated. The mechanical properties of steel-sheet piles, horizontal displacement of piles, and ground surface settlement in the anchor-cable crossing area were investigated based on in situ observations. Numerical investigations were performed using the finite element method (FEM). The effects of existing anchor cables on the mechanical behaviors of retaining structures, deformation variation of the ground, and stability of the excavation were studied. The results indicate that the composite supporting structures of steel-sheet piles and jet grouting piles have a positive effect on waterproofing and deformation control in areas with existing anchor cables. When the steel-sheet pile touched the anchor cable during pile jacking, the compressive stress at the pile cap increased rapidly until it reached 62.8 MPa (the maximum pressure provided by the pile-pressing machine), which is twice the pressure under ordinary conditions. The maximum horizontal displacement of the retaining pile, δv, increased linearly with the excavation depth He. Existing anchor structures behind the excavation can restrain the deformation of the ground and retain the structure to a certain extent. The δv value of the pile with existing anchor structures behind is 6.5 mm or approximately 0.01% of the He value, which is 70% of that of the retaining pile without existing anchor structures. “Groove type” ground surface settlements are found on both sides of the excavation. The maximum ground settlements δh are 0.29% He and 0.05% He, respectively. The plastic zone at both sides of the excavation bottom extends to the ground surface with an angle of about 45°. When an excavation fails, the plastic zone range in the ground with existing anchor cables is significantly larger than it is in the ground without anchor cables. The key contribution of this research is to provide an effective and low-budget treatment for pipe-jacking crossing through an anchor-cable group region. The findings from this study also provide industry practitioners with a comprehensive guide regarding the specific applications and mechanical performance of the crossing excavation for obstacle treatment.

Deformation Analysis of the Cable Reinforcement System of Large Section Box Culvert Roof Entry and Downward Penetration

For the underpass railway large-section box culvert jacking and pipe jacking project, the key to ensuring the normal operation of the existing railway is to maintain the smoothness and stability of the track, railway settlement monitoring and line reinforcement, and box culvert and pipe culvert attitude control are the keys to solving this problem. Taking the Beijing-Harbin high-speed railway project under a city road in Beijing as an example, the law of railway track settlement during the implementation of box culvert jacking was analyzed according to real-time monitoring data. The monitoring results show that accelerating the pouring of the bedding and grouting and strengthening the railway subgrade on both sides of the foundation pit can effectively control the settlement of the railway subgrade and reduce the impact of subsequent construction on the railway, and the line renovation and secondary grouting reinforcement can effectively improve the smoothness of the railway. Combined with the comparative analysis of numerical simulation results, the necessity of line refurbishment and rail fastening combination reinforcement in actual construction is verified.

Field mechanical properties of large section concrete pipes during jacking in fractured moderately weathered siltstone

In the construction of pipe jacking, due to the effect of jacking force, slurry pressure, axis deviation, stoppage and geological conditions, the mechanical behaviors of pipe are very complex. Additionally, most of the calculation models of pressure around the pipes in the existing standards only consider water and earth pressure, which is different from the actual situation. Therefore, this work aims to reveal the mechanical properties of concrete pipe during jacking and explore the calculation method of jacking force and frictional resistance. Based on the field monitoring of the pipe jacking project for utility tunnel in Hubei, China, the variation law of the contact pressure, slurry pressure and pipe strain were analyzed, and the jacking force and frictional resistance were calculated through the above parameters. The results show that it is more appropriate to use the rock collapse height instead of Terzaghi theory to calculate the earth pressure at the pipe crown in fractured rock mass. There is a significant negative correlation between the slurry pressure around the pipe and the jacking force. In the stratum with high permeability, choosing an appropriate lubricant injection interval can effectively improve the lubrication efficiency and reduce construction cost. In addition, the axial strain of pipe can reflect the variation of the jacking force, and the frictional resistance calculated by the effective earth pressure is closer to measured value. The calculation methods and related conclusions proposed in this paper can provide a valuable guide for pipe jacking in fractured rock mass.

Formulation optimization and performance analysis of the thixotropic slurry for large-section rectangular pipe jacking in anhydrous sand

When large-section rectangular pipe jacking is performed in anhydrous sand strata, due to the special geological condition and construction specification, there are specific requirements for the performance of thixotropic slurry. In this study, an optimized traditional slurry formula and a nano-modified slurry formula (with 2% nano-SiO2 added) suitable for large-section rectangular pipe jacking in anhydrous sand formations were proposed by conducting an L25 (35) orthogonal test and a two-factor test, respectively. Five indicators were used to select the optimal slurry component proportion and nano-additive and additive concentration, including plastic viscosity (PV), filter loss (FL), water dissociation ratio (WDR), thixotropic value (TV) and yield point (YP). The influence of the component content on the slurry properties was analysed. To preliminarily verify the drag-reducing effect of the slurries prepared according to the formulas, an interface friction test was designed. The interface friction test results show that the optimized traditional slurry can reduce the pipe-soil friction coefficient to 64.7%, whereas the nano-modified slurry is 54.9%. Through scanning electron microscopy (SEM) observations, the micro mechanisms of the slurries were investigated. Furthermore, the formulas were applied in a practical pipe jacking project, and the jacking load and soil settlement were well controlled throughout the application period.

Design and Analysis of Grouting Pressure in Slurry Pipe Jacking Based on the Surrounding Soil Stability Mechanical Characteristics

In slurry pipe jacking, lubricant slurry is commonly used to sustain against the displacement and pressure of the overcut area and reduce the interface friction of pipelines. Therefore, a reasonable grouting pressure should ensure the stability of surrounding soils, which is raised as a new method in this study. Not only ensure the grouting pressure is not too small to support the stratum effectively and reduce the frictional resistance but also ensure that the grouting pressure will not be too large to produce excessive deformation and affect the surrounding environment. First of all, the influence of grouting pressure on the stability of surrounding soil is analyzed, and the mechanical model of slurry grouting expansion is established. Then, the minimum grouting pressure is designed from the critical balance between radial expansion tension by grouting and loose earth pressure by jacking excavation, and the maximum grouting pressure is designed from the critical expansion pressure caused by grouting splitting. Finally, the rationality of grouting pressure design is proved by the engineering example of a slurry pipe-jacking project near Haikou Meilan Airport and on-site GPR detection test. All these work aims to raise a new theoretical solution of grouting pressure and provide theoretical reference for similar projects.

Performance analysis of utility tunneling data: A case study of pipe jacking in hard rock in Brittany, France

The increasing demand for renewable energy is accompanied with an urgent need for new and improved infrastructures worldwide, which in turn will require a greater number of utility tunneling projects in rock. Mainly due to tighter safety regulations, hard rock pipe jacking is getting increasingly important in the utility tunneling industry. Based on the example of the 530 m long Landivisiau utility tunnel case study, we present the first comprehensive pipe jacking study in high strength metamorphic rocks. The procedures and associated challenges of data analysis of a small-diameter pipe jacking project are presented and discussed. The tunnel has an outer diameter of 2.2 m and was excavated in Variscan basement rocks of Brittany. The geotechnical conditions at Landivisiau were very heterogeneous and stronger than expected, comprising fresh to highly weathered, weak to very strong gneiss, granite and schist with an UCS of up to 185 MPa. The TBM achieved an average advance rate of 17.3 mm/min and an average penetration rate of 3.4 mm/rev. The advance and penetration rates of the TBM are compared with results obtained by recent force estimation and penetration models. This study was conducted to raise awareness about the importance of using geological and technical data, to cope with increasingly strict controls by local authorities and to provide a foundation for further analysis and use of data, especially with respect to future automated tunneling.

Research on Dewatering Characteristics of Waste Slurry from Pipe Jacking Construction.

A large amount of waste slurry is produced during the construction of pipe jacking projects. To avoid the waste slurry occupying too much urban land, it needs to be rapidly reduced. Due to the complex composition of waste slurry, the existing dewatering methods face the problem of low efficiency, and the soil after dewatering is difficult to recycle as soil materials due to high water content and low strength. There is currently a lack of research on dewatering and resource utilization of waste slurry from pipe jacking projects. In response to this problem, this paper studies the flocculation-settling characteristics of waste slurry and the mechanical properties of solidified sediment. It was found that the anionic polyacrylamide (APAM) 7126 obtained the best separation effect if the waste slurry contains bentonite, which increases the zeta potential, resulting in poor separation. Thus, FeCl3·6H2O and APAM 7126 can be used as compound conditioners. The sediment after settling was further added with 20–30% sulphate aluminum cement (SAC), and the unconfined compressive strength of the solidified sediment for 3 days could exceed 30 kPa. After flocculation-settling and solidification treatment, the waste pipe jacking slurry can be quickly dewatered into a soil material with a certain strength, which provides a reference for engineering applications.

Numerical Simulation of Mechanical Response of Bridge Foundation and Existing Tunnel Caused by Pipe Jacking Construction

Upward ( phase i ) pipe jacking project of hangzhou water intake is near existing bridge foundation and operating tunnel. In order to investigate the influence of pipe jacking construction process on existing structures, Plaxis 2D finite element software was used to simulate the horizontal and vertical displacement of existing structures caused by pipe jacking construction. The calculation results show that: The horizontal displacement of bridge pile foundation is nonlinear distribution. There is a bending point in the pile foundation. The maximum and minimum horizontal displacement are 0.71 mm and-0.84 mm, respectively. The maximum vertical settlement is only 0.29 mm. The horizontal displacement of the sidewall of the tunnel structure is nonlinear distributed, and the displacement near the pipe jacking is relatively large, but the maximum displacement is only 0.13 mm. The vertical deformation of tunnel structure is mainly uplift deformation, and the uplift near the pipe jacking is obvious, but the extreme value of uplift is only 0.09 mm. Thus, the impact of pipe jacking construction on bridges and tunnels is very limited. The research results are of great significance to the safety evaluation of pipe jacking engineering near construction.

Analysis on Sealing Performance for a New Type of Rubber Olecranon‐Shaped Sealing Ring in Pipe Jacking Joint

To address the easy damage of rubber sealing rings for pipe joints used in China’s first rock pipe jacking project, the launch of research concerning the optimization design of rubber ring structure was decided. However, modification based on the existing production mold was required, to prevent the construction period and cost from exceeding limits. Utilizing the optimization experience, the stress and waterproof property variations of rubber ring before and after optimization during the pipe translation and deflection were initially analyzed via the ADINA software. Meanwhile, the correct orientation of the ring optimization criteria was confirmed through the field test. Next, the effects of key structural parameters on the contact length and maximum contact pressure of rubber ring were quantified, thereby obtaining the sensitivity correlations between five key parameters of ring optimization to further establish the criteria for rubber ring optimization. The findings of this study offer safe construction suggestions for pipe jacking projects.

Differential Analysis and Prediction Optimization of Ground Surface Settlement Induced by Quasi‐Rectangular Shield and Pipe Jacking Tunnelling

The shield method and pipe jacking method will impact the ground surface and surrounding settlement during tunnel construction. Due to their different tunnelling principles and their cross‐section characteristics, the impact on the stratum is often different. To study the differences between the two construction methods on ground surface settlement, numerical simulations, Peck empirical formulas, and field measurement data were used for analysis and comparison in this work. Two correction coefficients α and λ are introduced for correction on the basis of the DOT Peck formula, and the analysis of sensitivity factors for the ground settlement for the two construction methods is carried out. The numerical simulation results show that the ground settlement induced by pipe jacking construction is smaller than that of the shield, and this simulation result is confirmed by the field measurement result. When λ is selected from 0.85 to 0.91 and α from 1 to 1.1 for the shield project, 1.2 to 1.4, and 1.4 to 1.6 for the pipe jacking project, the modified formula can better predict the ground surface settlement. According to the sensitivity factor analysis, grouting pressure and elastic modulus of grout material exert a more significant influence on pipe jacking construction. The retreat of the pipe section caused by the tunnelling pressure difference will lead to 0 mm ∼ 1.93 mm fluctuation on the ground surface.

Estimations of the Jacking Forces of Large-Sized Rectangular Jacking Pipes Based on a Displacement Control Method

In the present study, based on previous research results, a finite element method that considered the grouting pressure and displacement control of the tube-soil side friction coefficients was established for the purpose of estimating the jacking forces of large sections of rectangular pipe jacking. Furthermore, the pipe jacking project of Zhong-Zhou Avenue was taken as an example in this study, in which the rectangular pipe jacking models A1 and B1 under silty clay geological conditions were established. The two estimation models were verified using the pipe jacking cases A2 and B2, respectively. The estimation model can effectively estimate the jacking force, and the rectangular jacking force is distributed as a logarithmic function with the jacking distance. The shallow buried rectangular pipe jacking has some common characteristics in buried depth, grouting pressure, the length-width ratio of outer diameter, construction geological conditions, and so on. The main independent factors that affect the jacking force are the buried depth and the outer perimeter of the jacking pipe. Based on the numerical model of case A1 and case B1, the logarithmic functions of jacking force of case A1 and case B1 with jacking distance were obtained by changing the buried depth. The calculation formula of the jacking force can reflect the variation law of the jacking force to some extent.