Yaolin Yi

Fluidic Drag Estimation in Horizontal Directional Drilling Based on Flow Equations

AbstractHorizontal directional drilling (HDD) is a trenchless technology used to install underground utilities. The force required to pull a pipe through the borehole during installation is crucial to design engineers. Various methods have been proposed to estimate the pullback load, each dealing with fluidic drag in a different way. Limitations in fluidic drag estimation by current design procedures have revealed the significance of having a reliable method for calculation. This paper proposes a new method to calculate fluidic drag based on annular flow equations. This method is used to calculate viscous drag for two HDD case studies, and the results are compared to the estimations by current methods, such as PRCI and ASTM F1962. Pullback load estimation based on the new method agrees well with the actual installation loads. This paper also investigates the impact of design factors on fluidic drag by presenting a sensitivity analysis over a practical range of related parameters. The ratio of pipe radius ...

Clogging potential of tunnel boring machine (TBM): a review

Tunnel boring machines excavating through soft soils face different challenges, one of which occurs when the soil sticks to the cutter face or the conveyor band and obstructs the machine. This phenomenon, commonly referred to as clogging, leads to wearing of the cutting wheel and transportation system, delays in the time schedule and economic loss. Although several laboratory devices can evaluate the adhesion mechanism of soil to metal, the method to measure adhesion has not been standardised. As clogging is also directly related to the construction phase, engineers are more concerned with methods to avoid this problem during construction. In this regard, the application of soil conditioners has become useful, the benefits of which include torque reduction, easier soil manageability and clogging reduction. However, the effectiveness of the soil conditioners is difficult to evaluate. To provide some insight into the topic, this paper describes the basic mechanism of clogging, the key parameters for its evaluation, the laboratory tests conducted up to date, the classification diagrams developed to assess clogging risk and mitigation of this risk in underground tunnelling. This paper also describes some of the additives and their functions, the ratios used for measurement and application, and the current tests to evaluate their performance. Finally, the conclusions summarise the current findings in the issue of clogging, pointing to the advantages and shortcomings of previous research, as well as some lines of investigation to improve identification and mitigation of this problem.

Mechanical properties of clayey soil relevant for clogging potential

Due to its advantages, including reduced operation time and cost, tunnelling with boring machines in urban areas has become a popular technique over hand-tunnelling or open-trench excavations. However, tunnelling in clayey soil poses a great challenge since the mechanical and physical properties of clays cause different issues, one of which is clogging. To solve this problem, engineers have treated the soils with different soil conditioners in order to change their rheological properties, improve their manageability and eliminate undesirable characteristics. However, the root of this problem is the lack of understanding the phenomenon and characterising it on the framework of soil mechanics. By considering the use of polymers, this paper aims to provide information regarding the theory involved in this mechanism and the factors influencing clogging potential. The authors present a systematic study of the physical and mechanical properties of plain soil and conditioned soil, which includes a direct shear test, vane shear test and Atterberg limits test. Results show that the initial water content, roughness of shear plate and percentage of additive have a significant effect on the clogging potential. Additionally, the results are plotted on an empirical diagram to understand the clogging potential by relating the clogging potential to soil properties.

General Method for Pullback Force Estimation for Polyethylene Pipes in Horizontal Directional Drilling

AbstractThis paper proposes a general method for estimating pullback force applied on polyethylene (PE) pipes during horizontal directional drilling (HDD) installations based on adapting the Capstan equation to a PE pipe negotiating a curved bore. Compared to current standards, this method can be implemented in any installation regardless of the bore geometry, such as ground surface grade or number of segments composing the bore path. To verify the proposed method, pullback data collected from an HDD installation project is compared to forces estimated by the proposed method as well as standard methods. This paper demonstrates the proposed method’s ability in estimating a more-accurate pullback load.

Finite-Element Analysis of Highway Embankment Made from Tire-Derived Aggregate

Tire-derived aggregate (TDA) has been used in many civil engineering applications. Despite its successful use in the past, the amount of experimental research available on TDA applications is not sufficient to provide data for the evaluation of an appropriate constitutive model. The majority of TDA constitutive models have been developed from laboratory tests performed on tire chips smaller than those used in field applications. In this study, nonlinear elastic material models, with an elastic modulus that varies as a function of vertical stress, have been developed for TDA produced from passenger and light truck tire (PLTT) and off-the-road (OTR) vehicle tires. The material model for TDA is established based on previous large-scale laboratory constrained compression tests conducted on TDA up to 300 mm in size. The model is used in a finite-element (FE) analysis using geotechnical software to predict the settlement of full-scale test embankment during construction. The results indicate that the settlements obtained from the FE analysis agree with the settlements measured in the field during construction of full-scale test embankment. This paper also provides design charts to compute overbuild required on top of TDA layer(s) to compensate immediate compression under an applied load during the placement of cover on top of TDA.

Estimation of Hydrokinetic Pressure and Fluidic Drag Changes during Pipe Installations via HDD Based on Identifying Slurry-Flow Pattern Change within a Borehole

AbstractThis paper proposes a new method for hydrokinetic pressure and fluidic drag evaluation of non-Newtonian power-law slurries flowing within a borehole during horizontal directional drilling (...

Case Study of Pipeline Installation Using a Modified Guided Boring Method

AbstractThe Guided Boring Method (GBM), also referred to as Pilot Tube Microtunneling (PTMT), is a widely used trenchless technology for pipeline installation with grade precision. However, PTMT is not applicable in nondisplaceable soils, where it is unable to install pilot tubes. In this context, this study introduces a Modified Guided Boring Method (MGBM) for pipeline installation in nondisplaceable soils. The guided boring is performed without the use of pilot tubes and coupled with hollow-center augers for target site path. This study presents the first pipeline installation project performed with the MGBM, and the case study results confirm that this technology can successfully install pipelines with grade precision in hard ground conditions. This study also assesses the MGBM’s economic performance using the project’s productivity and risk measurements, which can be used to facilitate budget and time estimates of future projects.

Annular fluid pressure estimation during pilot boring in horizontal directional drilling using the Bingham plastic flow model

The Bingham plastic flow model is predominantly used to predict the annular pressure in horizontal directional drilling (HDD); however, it estimates conservatively when using a two-speed viscometer with a high shear rate range of 300-600 RPM to determine the Bingham rheological parameters of the fluid. In this study, instead of the two-speed viscometer, a six-speed viscometer (shear rates of 3, 6, 100, 200, 300, and 600 RPM) was used in two HDD cases, and the annular pressure during pilot boring was predicted using the Bingham model with rheological parameters determined based on different shear rate ranges. The predicted pressures were compared to field measurements, and the comparison indicated favourable results for the Bingham model at the low shear rate range of 100-200 RPM. However, at high shear rate ranges of 200-300 and 300-600 RPM, the model overestimated the measurement up to 30% along the drill path and approximately 110% near the exit pit.

Comparison of different methods for normal stress calculation during pipe jacking/microtunneling

Vertical earth load on pipes is an important factor during pipe jacking/microtunneling as it largely affects the jacking force. Although several methods can determine the normal load, the difference among them in calculating vertical normal stress is quite large. Hence, this paper provides an extensive analysis of nine different models/standards and their variations based on experimental data as well as a parametric study. The results show that some models predicted normal stress values close to the measured value, while others give much higher or lower values than the measurement. This discrepancy is due to the variation of assumptions of different methods. To identify the influence of parameters on normal stress, a parametric study is also conducted to reveal the effect of different parameters on arching factor as well as normal earth stress.

Predicting Soil Expansion Force during Static Pipe Bursting Using Cavity Expansion Solutions

AbstractThe prediction of total pull force is critical for static pipe-bursting installation. As a major component of the total pull force, soil expansion prediction is also important; however, there are currently limited methods available for such prediction. In this paper, three cavity expansion solutions were used to predict soil expansion pressure acting upon the expander (bursting head) during static pipe bursting. The determined soil expansion pressure was then used to calculate the expansion force required for pipe bursting with or without consideration of the soil collapse. Calculated results were then compared with those from laboratory pipe-bursting experiments to evaluate the feasibility of the calculation methods. The comparison indicated that the large-strain cavity expansion solution reasonably predicted the soil expansion force. The small-strain solution significantly overestimated the soil expansion force. Additionally, considering soil collapse during pipe bursting resulted in a remarkabl...