Professor’s HDD study wins research award
Professor Wu Xiaoming and his research team at the China University of Geosciences developed a series of effective scientific methods to efficiently and safely install underground utilities using horizontal directional drilling (HDD) in a range of complex subsurface conditions.
A number of years of research was collated into the winning entry titled ‘Research on HDD Technology for Pipeline Installation under Complex Underground Conditions’. The team divided complex geological formations into six categories for the purpose of examination:
- silt soil
- weak cemented formation
- water sensitive formation
- water soluble formation
- lost circulation
- hard rock.
The team then developed technical measures for these soil types based on the different unfavourable influences they had on HDD engineering operation indicators such as mechanical, physical and hydrological properties. Six different kinds of mud systems and corresponding formulations were developed to meet the main demands of cutting transportation, borehole support, plugging and lubrication.
The research team developed a theoretical calculation model and 3D visualisation design software for HDD trajectories, along with a 3D geometric algorithm to avoid the original underground pipeline, taking into consideration the bending strength of the pipeline and its construction ability.
An automatic surveying instrument used to assess the borehole condition was also manufactured. This was used to monitor complex data such as torque calculation. Formula during reaming was derived for extrusion, cutting, and roller bits, the optimization design calculation model of reaming diameter, pullback force and mud flow.
The torque calculation formula during reaming analysed extrusion, cutting performance, and roller bits condition. At the same time the optimisation design calculation model of reaming diameter, pull-back force and mud flow was established, and an automatic surveying instrument to assess bore hole condition was developed.
The Matlab numerical calculation platform and analysis software was used to forecast emerging grout, ground uplift, subsidence, and mud materials for leak-proof and subsidence proofing. Corresponding control measures for drilling operation and were also established.
Taking the pipe wall friction resistance, bending resistance and casing end resistance as the main pull-back force into consideration, the HDD pull-back force pre-calculation model and software were established to incorporate 16 factors and five technical measures that were put forward to reduce the pull-back force.
The pipeline 3D trajectory surveying instrument was developed with a maximum surveying distance up to 1,000 m and errors of less than 250 mm. This was applied through manpower, mechanical or wireless operation models. At the same time the regional underground pipeline database was established.
Professor Wu Xiaoming lectures in Investigation Engineering at China University of Geosciences. He and his team’s research results have been successfully applied to a variety of complex projects, solving numerous engineering problems. He has also setup a series of Trenchless Technology training courses in China for 10 consecutive years.
This article was featured in the Winter 2017 edition of Trenchless International. To view the magazine on your PC, Mac, tablet, or mobile device, click here.
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