Drilling wells in unstable water-bearing topsoil or fractured rock formations and karst formations with large water content (eg greater than 30 m3/h ), special technical measures or other special measures used to reinforce surrounding rock and isolate groundwater sources to improve construction conditions Scientific methods, collectively referred to as special well-drilling methods.
Common well drilling methods commonly used are concrete curtain method, sinking method, freezing method and grouting method.
Sinking method:
The sinking method is a special well-drilling method that prefabricates a section of the well wall and then digs into the sinking wall and correspondingly connects the long well wall on the ground. In order to reduce the sinking resistance and avoid the deviation and cracking of the borehole wall, in addition to the ordinary caisson method, there is also a submerged mud flooding caisson and a wall post-pressure gas flooding sinking method.
The sinking well consists of a set of wells, a well wall and a cutting edge. The casing is the lock, and its net diameter is larger than the outer diameter of the caisson by about 1.5m . Its function is to protect the wellhead, install the guiding device and store the mud, etc. It is pre-constructed before the sinking. The well wall is generally used as a permanent support in the future. It is a reinforced concrete structure with a thickness of about 1.0 m . It is determined according to the sinking capacity and strength. In addition to the calculation of permanent loads in strength design, construction loads should also be considered. The role of the cutting edge is to cut into the soil layer to overcome the frontal resistance of the sinking well, to close and prevent the back of the wall from flowing sand, mud or pressure into the well. The structure should have sufficient strength, can withstand the reaction force of the soil layer, side pressure, shear force and partial pressure when encountering large pebbles, and impact force when sinking. Usually, steel blade feet or steel shoe feet are used.
Common well drilling methods commonly used are concrete curtain method, sinking method, freezing method and grouting method.
Sinking method:
The sinking method is a special well-drilling method that prefabricates a section of the well wall and then digs into the sinking wall and correspondingly connects the long well wall on the ground. In order to reduce the sinking resistance and avoid the deviation and cracking of the borehole wall, in addition to the ordinary caisson method, there is also a submerged mud flooding caisson and a wall post-pressure gas flooding sinking method.
The sinking well consists of a set of wells, a well wall and a cutting edge. The casing is the lock, and its net diameter is larger than the outer diameter of the caisson by about 1.5m . Its function is to protect the wellhead, install the guiding device and store the mud, etc. It is pre-constructed before the sinking. The well wall is generally used as a permanent support in the future. It is a reinforced concrete structure with a thickness of about 1.0 m . It is determined according to the sinking capacity and strength. In addition to the calculation of permanent loads in strength design, construction loads should also be considered. The role of the cutting edge is to cut into the soil layer to overcome the frontal resistance of the sinking well, to close and prevent the back of the wall from flowing sand, mud or pressure into the well. The structure should have sufficient strength, can withstand the reaction force of the soil layer, side pressure, shear force and partial pressure when encountering large pebbles, and impact force when sinking. Usually, steel blade feet or steel shoe feet are used.
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