Steerable surface-launched equipment for the installation of pipes, conduits and cables. Applied to intermediate sized drilling rigs used as either a small directional drilling machine or a large guided boring machine. Tracking of the drill string may be achieved be either a downhole survey tool or a locator.
US customary unit for flow measurement. One MGD equals 43.81 liters per second.
A term sometimes applied to Guided BoringMethod for the installation of pipes, conduits and cables using a surface-launched drilling rig. A pilot bore is drilled using a rotating drill string and is then enlarged by a back reamer to the size required for the product pipe. The necessary deviation during the pilot boring is provided by a slanted face to the drill head, an asymmetric drill....
An interface within the excavated tunnel zone between two geological units that have a significant contrast in engineering properties (e.g., rock overlain by soft ground, or very soft, low-strength soil overlain or underlain by a very stiff, high-strength soil).
The excavated tunnel zone, without a defined interface, that contains soil and coarse fractions of gravels, cobbles, and boulders (i.e., silt with boulders). This term is not currently defined by ASTMAmerican Society of Testing and Materials; technical organization formed for the development of standards on characteristics and performance of materials, products, systems and services, and the promotion of related knowledge. or USCS.