Evaluation of the gradient precision of the horizontal directional drilling technique for the installation of gravity sewers / Avaliação da precisão da declividade da técnica de perfuração direcional horizontal para instalações de redes de esgoto

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The present work is focused on the horizontal directional drilling (HDD) method to install gravity sewers. The results of different techniques are described intending to meet the demands of gradient. Therefore, 4 experimental pilot bores were drilled simulating a section of those structures extending 30 m with HDPE pipelines of 125 mm external diameter. Those installations were engineered in the city of São Carlos, Brazil, in a clayey sand. For each of the 4 installations a distinct constructive process was adopted. Such characteristic was on account of the diameter of the selected reamer, the number of reamer steps and the vertical drills performed to relieve the pressure in the annular space, as well as the direct depth measurements of the pilot hole. After installing the pipes, altimetric measurements were performed inside them, hence enabling to quantitatively assess the obtained results. These results indicate the need to further refine the directional drilling technique for sanitary sewers. Yet it can be seen that the employed variations for each of the holes lead to an improved course of action with the observed results. Such improvement is perceived in the holes where the selected reamer had a smaller diameter, hence allowing for less displacement in the pipes final position. Also emphasized are the resulting benefits of the vertical drills that lead to less pressure in the annular space, as well as enabling altimetric measurements of the pilot hole position. Thus, it is presumed that with further experiments and technological developments the final objective is reached, meaning, putting into effect constant and low level gradient sewer networks. Tests for precision and accuracy assessment of the tracking system were also performed in each tube installed. The tracking system is responsible for providing information related to position and temperature of the drill head during the drilling operation. The steps for the development of a new HDD solution for sewer installation are presented. The idea is based on the application of a tensile force to an element external to the product, aiming at attaining a constant gradient. Equipments and procedures developed for this new technique are described.

ASSUNTO(S)

declividade esgoto gravitacional gradient. horizontal directional drilling (hdd) gravity sewer cálculo de desvios deviation calculations perfuração direcional horizontal (hdd)

ACESSO AO ARTIGO

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