1. Prevention of hole collapse

water well drill pipeBefore construction, drilling measures should be formulated according to the engineering geological characteristics of the formation, and the selection of reasonable mud parameters is an important part of the prevention of hole collapse. CASING USES10mm thick steel plate processing, the inner diameter is 20~40cm larger than the design aperture, and the upper part is provided with 2 overflows. When burying, the top of the pile casing shall be 0.5 m higher than the ground, and the depth of the deep riverbed shall be not less than 3m at the soft soil, silt and sand. When the soft soil and silt layer is thick, it shall go deep into the impermeable layer of clay for 1.5m. Clay mud is used for pore forming to protect the wall. The relative density of the mud is controlled to be 1.2~1.6, the sand content is not more than 4%, the viscosity is 16~28s, the colloid rate is not less than 95%, the water loss rate is not more than 20ml/30min, the mud skin thickness is not more than 3mm/30min, and the PH value is 8~11.water well drill pipeKeep the mud surface of the retaining wall not lower than the top surface of the casing.0.5m. When the formation is poor, increase the mud density to balance the pressure in the hole, and appropriately reduce the drilling speed to effectively prevent hole collapse.

2. Partial hole prevention

Level and compact the stratum at the substructure of the drilling rig, and lay sleepers at the bottom of the drilling rig to prevent uneven settlement of the stratum. The positioning of the drilling machine should be accurate, and the bit alignment error is less2cm, keep the center of the rotary table of the drilling rig, the center of the crane and the center of the casing on the same vertical line to avoid the displacement of the base of the drilling rig. During the construction process, check whether the drilling rig is horizontal and drill to 1/2 of the depth of the hole,water well drill pipeCheck the verticality of the borehole in time after drilling.

3. In case of hole collapse, hole deviation or slurry spurting around the casing during drilling, the following measures can be taken to deal with it.

When the drill hole is inclined, lift the drill bit to the offset hole, and slowly and repeatedly sweep the hole for correction. When the drilling inclination is seriously invalid, backfill the hole to the upper part of the partial hole.0.5 meters shall be re-drilled after settling the chamber.

In the drilling, if the water level in the casing drops sharply and bubbles emerge, the hole may collapse. For slight hole collapse, take measures such as slowing down the drilling speed and increasing the mud density to pass through the collapsed hole; when the hole collapse is serious, stop drilling immediately and fill with clay, and then drill in after the hole wall is stable.

water well drill pipeDuring the construction of bored piles, the construction must be carried out in strict accordance with the pouring of one piece after the hole is formed, so as to prevent the hole from collapsing due to too long drying time after the hole is formed. At the same time, the construction shall be organized in strict accordance with the construction sequence in the construction technical disclosure, and the minimum time interval between two adjacent piles shall not be less24 hours to prevent string holes during construction.

After concrete pouring, the hole hole must be covered with steel mesh or wood to prevent personnel from falling into the hole and causing safety accidents.