scholarly journals Research on the Slurry for Long-Distance Large-Diameter Pipe Jacking in Expansive Soil

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Xian Yang ◽  
Yang Liu ◽  
Chao Yang
Keyword(s):  
Large Diameter ◽  
Soil Layer ◽  
Expansive Soil ◽  
Expansion Ratio ◽  
Water Dissociation ◽  
Long Distance ◽  
Calculating Method ◽  
Water Based ◽  
Pipe Jacking ◽  
Jacking Force

When the pipe jacking technology is applied in expansive formation, the soil around the pipe will easily absorb water from the slurry and expand to wrap up the pipe, producing an excessive pipe jacking force. A water-based slurry formula suitable for pipe jacking in expansive soil layer was proposed in this paper. Firstly, the key design points of pipe jacking slurry in expansive soil were put forward. Secondly, plant glue, potassium humate, Na-CMC, and graphite powder were chosen as treating agents to improve the slurry performance. The effect of addition levels of different treating agents on the funnel viscosity, filter loss, expansion ratio, friction coefficient and water dissociation rate of the slurry were tested. Thirdly, based on the results of single-factor tests, a water-based slurry formula suitable for pipe jacking in expansive soil was obtained. Finally, the slurry formula was applied in a practical pipe jacking project in expansive formation, and the jacking force was controlled well in the whole jacking process. The new water-based slurry is cheap and practical and has no pollution to environment. Furthermore, a simple and practical calculating method of the pipe jacking force was presented. The comparison of the calculated and measured pipe jacking force shows that the simple calculating method can estimate the jacking force well. Improving slurry performance to reduce jacking force in pipe jacking and predicting pipe jacking force accurately can help reducing the investment for counterforce wall and jacking system in pipe jacking engineering.

scholarly journals Experimental Study on the Complex Contact Frictional Property of an Ultralong Distance Large-Section Concrete Pipe Jacking and Prediction of Pipe String Stuck

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Ziyong He ◽  
Jiangong Chen
Keyword(s):  
Contact Surface ◽  
Frictional Resistance ◽  
Test Method ◽  
Frictional Property ◽  
Test Results ◽  
Long Distance ◽  
Bentonite Slurry ◽  
Pipe Jacking ◽  
Jacking Force ◽  
Variation Trends

Line 2 of the Guanjingkou Pipe Jacking Project in Chongqing encountered a pipe sticking problem, whose occurrence was inevitably attributed to the higher total frictional resistance of pipe strings rather than the maximum jacking force. Line 1, which is about to start construction, has basically the same construction environment as Line 2 using the same microshield and pipe string sizes. To avoid repeating the pipe sticking problem of Line 2, the mutual friction characteristics between the surrounding rocks and jacked pipe strings are studied for Line 1 by adopting the same test method under seven complex contact conditions (the presence or various combinations of three substances, i.e., extrapipe string field debris, bentonite slurry, and sand-laden waste slurry, on the jacked pipe string-surrounding rock contact surface are mainly considered). The results show that sufficient bentonite slurry can effectively reduce the frictional resistance, and when the amount of bentonite is insufficient, the average friction coefficient (AFC) of the later contact surface increases by 50%∼70%. The comparison of the monitored versus predicted jacking forces indicates that the value predicted by the test is slightly higher than the monitored force and the variation trends of the two match well, thus proving the correctness of the test results. It is possible to continue predicting the variation trends of the jacking force and frictional resistance based on the contact situation outside the pipe string wall, which greatly lowers the probability of re-encountering pipe sticking. The test results not only explain the important role of bentonite slurry in reducing the pipe string wall frictional resistance but also suggest that an increase in the pipe string wall frictional resistance resulting from the complex contact inflow into the overexcavation gap is the root cause of pipe sticking; moreover, the number of jacked pipe strings matching a single IJS is the second cause of pipe string sticking. The methodology of this study can provide a reference for other studies concerning the jacking force of long-distance rock microshield tunnelling.

Development of X80M Line Pipe Steel for Spiral Welded Pipes With Low Temperature Toughness and Excellent Weldability

2014 ◽  
Author(s):  
Nuria Sanchez ◽  
Özlem E. Güngör ◽  
Martin Liebeherr ◽  
Nenad Ilić
Keyword(s):  
Low Temperature ◽  
Life Cycle Cost ◽  
Volume Fraction ◽  
Large Diameter ◽  
Pipe Production ◽  
Strain Accumulation ◽  
Long Distance ◽  
Line Pipe ◽  
Low Temperature Toughness ◽  
Welded Pipe

The unique combination of high strength and low temperature toughness on heavy wall thickness coils allows higher operating pressures in large diameter spiral welded pipes and could represent a 10% reduction in life cycle cost on long distance gas pipe lines. One of the current processing routes for these high thickness grades is the thermo-mechanical controlled processing (TMCP) route, which critically depends on the austenite conditioning during hot forming at specific temperature in relation to the aimed metallurgical mechanisms (recrystallization, strain accumulation, phase transformation). Detailed mechanical and microstructural characterization on selected coils and pipes corresponding to the X80M grade in 24 mm thickness reveals that effective grain size and distribution together with the through thickness gradient are key parameters to control in order to ensure the adequate toughness of the material. Studies on the softening behavior revealed that the grain coarsening in the mid-thickness is related to a decrease of strain accumulation during hot rolling. It was also observed a toughness detrimental effect with the increment of the volume fraction of M/A (martensite/retained austenite) in the middle thickness of the coils, related to the cooling practice. Finally, submerged arc weldability for spiral welded pipe manufacturing was evaluated on coil skelp in 24 mm thickness. The investigations revealed the suitability of the material for spiral welded pipe production, preserving the tensile properties and maintaining acceptable toughness values in the heat-affected zone. The present study revealed that the adequate chemical alloying selection and processing control provide enhanced low temperature toughness on pipes with excellent weldability formed from hot rolled coils X80 grade in 24 mm thickness produced at ArcelorMittal Bremen.

Pressure Test Planning to Prevent Internal Corrosion by Residual Fluids

2012 ◽  
Author(s):  
Trevor Place ◽  
Greg Sasaki ◽  
Colin Cathrea ◽  
Michael Holm
Keyword(s):  
Structural Integrity ◽  
Large Diameter ◽  
Long Distance ◽  
Internal Corrosion ◽  
Pressure Testing ◽  
Practical Strategy ◽  
Leak Testing ◽  
Pressure Test ◽  
Transmission Pipeline ◽  
Pipeline Project

Strength and leak testing (AKA ‘hydrotesting’, and ‘pressure testing’) of pipeline projects remains a primary method of providing quality assurance on new pipeline construction, and for validating structural integrity of the as-built pipeline [1][2][3]. A myriad of regulations surround these activities to ensure soundness of the pipeline, security of the environment during and after the pressure testing operation, as well as personnel safety during these activities. CAN/CSA Z662-11 now includes important clauses to ensure that the pipeline designer/builder/operator consider the potential corrosive impacts of the pressure test media [4]. This paper briefly discusses some of the standard approaches used in the pipeline industry to address internal corrosion caused by pressure test mediums — which often vary according to the scope of the pipeline project (small versus large diameter, short versus very long pipelines) — as well as the rationale behind these different approaches. Case studies are presented to highlight the importance of considering pressure test medium corrosiveness. A practical strategy addressing the needs of long-distance transmission pipeline operators, involving a post-hydrotest inhibitor rinse, is presented.

Effect of Expansion Ratio and Wall Thickness on Large-Diameter Solid Expandable Tubular after Expansion

2021 ◽  
Author(s):  
Changshuai Shi ◽  
Kailin Chen ◽  
Xiaohua Zhu ◽  
Feilong Cheng ◽  
Yuekui Qi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Internal Pressure ◽  
Wall Thickness ◽  
Performance Test ◽  
Large Diameter ◽  
Expansion Ratio ◽  
Fe Model ◽  
Laboratory Test Results ◽  
Low Efficiency ◽  
Pressure Resistance

Abstract The large-diameter solid expandable tubular with a smaller wall thickness faces the risk of internal pressure burst and external squeeze collapse in repairing damaged casing well. The internal pressure and external squeezing resistance calculation of the tubes using the analytical method require many expansion experiments and post-expansion tensile experiments, resulting in high costs and low efficiency. This paper gives a set of laboratory expansion and post-expansion performance test, which is based on the laboratory experiment and mechanical properties of material expansion. Two materials are studied: 316L and 20G. Then it analyses the error and causes of the error in the traditional analytical algorithm. Besides, it establishes an accurate finite element (FE) model to study the quantitative influence of expansion ratio and wall thickness on the burst strengths and collapse strengths of the tube. The results show that the toughness and hardening ratio of 316L is better than 20G at the same expansion ratio. The numerical simulation results of the model can effectively simulate the expansion process and the mechanical properties of SET in good agreement with the laboratory test results. The expansion ratio and wall thickness affect the mechanical properties after expansion. Thus the quantitative laws of the expansion driving force, internal pressure resistance, and external squeezing resistance under different variables are summarized. To ensure the integrity of the reinforced wellbore, the expansion ratio should not exceed 12.7%. In the current study lays a theoretical basis and technical support for optimizing SET and preventing downhole accidents.

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