Manual of XZ320 Horizontal Directional Drill
45
9.6.4 Mud effusion prevention measures
9.6.4.1 Design bore depth shall be added from 6m to 9m and original depth
can be added from 9m to 12m.
9.6.4.2 Improve the drill bit structure to strive to mix mud in the bore into
mud.
9.6.4.3 Add mud viscosity, concentration, flow and floating and debris
removal ability of protective wall properly. A complete channel shall be
formed in the bore so that mud can effuse from the hole freely.
9.7 Continue to pump mud even if drill stops operation.
Drill stops operation due to various reasons during back towing and pipe
layout. Pipes which shall be welded and protective layers which shall be
repaired in the halfway may be disturbed by municipal administration. Mud
can not be pumped if drill bit stops operation if back towing and pipe layout
are required. Mud shall circulate in the hole to prevent from increasing
back towing force of set pipes and avoid burial. Mud pumping can not be
stopped especially for sandy stratum. Stop pumping dense mud before drill
stops operation under emergency conditions then mud shall be pumped for
10 minutes after re-drilling so that mud can exit the hole for back towing
and pipe layout.
9.8 Expanding efficiency
Torque and rotation speed of drill are in direct proportion of expanding
efficiency. Expanding efficiency relates to expanding soil layer, drill bit, mud
quality and mud consumption directly under rated torque and rotation
speed of drill. Clarify soil layer structure and soil quality composition, select
high-efficiency drill bit to cut the soil layer, mix mud and define mud
consumption to increase expanding efficiency.
9.9 Quick sand
Complete holes can not be formed after expanding of quick sand layer.
Quick sand has absorption force to bring resistance to set pipes. Heavy
gum solid mud will be used to slow down expanding speed so that mud
and quick sand can emulsify thoroughly. Quick sand will be floated in the
hole to eliminate absorption force. Quick sand will flow out of the bore with
mud during pipe layout.
9.10 Pipe deformation
Clay will form blocks for residue in the hole in high-viscosity stratum and it
is difficult to mix into mud. Mud blocks will be protruded and pipes will be
protruded with deformation during pipe layout. Pipes shall be set before
layout after multiple borehole cleaning to guarantee little deformation.
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