Semi-closed mud pressure maintaining and circulation technique in confined water stratum drilling construction

Abstract

The invention discloses a semi-closed mud pressure maintaining and circulation technique in confined water stratum drilling construction. (A) A drilling machine, a mud pit, a mud pump, an orifice sealing device and a solid-liquid separation device are separately installed; (B) a mud outlet of the mud pit is communicated with a mud inlet of the mud pump and a mud outlet of the mud pump is communicated with a mud inlet of the drilling machine; (C) a mud inlet of the solid-liquid separation device is communicated with a mud outlet of the orifice sealing device and a mud outlet of the solid-liquid separation device is communicated with a mud inlet of the mud pit; (D) according to pressure of the confined water in the drilling position and a pressure threshold value in the solid-liquid separation device with a stratum depth set, a pressure balance between mud in the drilling and water and soil on the stratum is formed; (E) a drill stem of the drilling machine performs drilling construction through the orifice sealing device. The semi-closed mud pressure maintaining and circulation technique in confined water stratum drilling construction does not only cause water and soil loss but also affect the normal propelling of drilling under the protection of the mud.

Description

Technical field [0001] The invention relates to equipment in the technical field of borehole construction in confined water stratum, in particular to a semi-closed mud pressure-maintaining circulation process for borehole construction in confined water stratum. Background technique [0002] In the construction of municipal tunnels, deep foundation pits and subways, part of the working face of the drilling construction is located below the groundwater level or the hole location is located in the confined water layer. When no measures are taken, accidents such as water inrush and sand inrush often occur. Causes serious soil erosion in the stratum, even the ground collapses, and damages surrounding structures. Therefore, in the process of horizontal drilling in confined water formations, the balance of water and soil pressure between the mud and the formation can slow down or avoid the disturbing impact of drilling construction on the original formation and reduce soil erosion. For...

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Problems solved by technology

Construction under this drilling device has the following disadvantages: 1) The mud pressure in the hole is unstable, and it is difficult to form a balance of water and soil pressure between the mud and the formation; 2) The drilling slag can only rely on the opening of the orifice pipe bypass valve, It is easy to cause water gushing and sand gushing

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