To create a route for a new pipe, horizontal directional drilling uses drilling mud to stabilize the borehole, remove the soil cuttings, cool the drilling bit, and lubricate the new pipe as it is pulled back into the borehole. However, if the pressure of the drilling mud becomes too large, it can cause tensile fracture in the soil or unconfined plastic flow, which leads to mud movement through the soil out to the ground surface.
Consultants use an equation developed considering cavity expansion of the borehole to prevent blowout of the soil during the drilling process. However, there has been no test data for use in assessing the available methods for estimating maximum mud pressure.
David designed and conducted both small scale and large scale laboratory tests to develop seminal data for assessment of the mud pressure models.
David and Hongwei Xia presented a poster at the 2007 No-Dig conference in San Diego. The work described their tests of hydrofracture in sand. The poster was voted runner up in the NASTT student poster competition.
Download Complete Research Summary (PDF 220KB)