I. Process characteristics of undisturbed earth taking and pressing grouting pile
1, strong adaptability:This TYPE OF PILE IS SUITABLE FOR CLAY SOIL, silt soil, fill soil and other soil, and can be pile in the soft soil with reduced diameter, shifting sand layer, sand pebble layer, groundwater and other complex geological conditions.
2Pile quality is good:Because the concrete is pressed into the hole from the center of the drill pipe, the concrete has the characteristics of compactness, no broken pile, no shrinkage neck and so on, and the soil around the pile hole has the effect of penetration and compaction.
3High bearing capacity of single pile:Because OF THE continuous pressure irrigation superfluid concrete wall protection hole, the soil around the pile hole has penetration and compaction effect, improve the lateral friction resistance of the soil around the pile, so that the pile foundation has a strong bearing capacity, pull force, horizontal force resistance, small deformation, good stability.
Second, the main points of the construction technology of the original earth taking and pressing grouting pile
1, when the need to pass through old clay, thick sand, gravel soil and plasticity index is greater than25The clay should be tested.
2After positioning the drill, it shall be rechecked, and the deviation between the drill bit and the pile site shall not be greater than20, drilling speed should be slow when opening holes; Do not reverse or lift the drill pipe while drilling.
3In the process of drilling, when encountering stuck drilling, drilling rig shaking, deflection or abnormal sound, drilling should be stopped immediately, find out the reason, and take corresponding measures before continuing the operation.
4 ,According to the design strength grade of pile concrete, the concrete mix ratio should be determined by test. The concrete slump should be180～220 ; Coarse aggregate can be used pebble or gravel, particle size should not be greater than 30; Fly ash or admixture can be added.
5Concrete pump should be based on pile diameter selection, concrete transport pump pipe layout should reduce the bend, the distance between the concrete pump and the drill should not exceed60m.
6The pumping and pressure irrigation of pile concrete shall be carried out continuously. When the drill is shifted, the concrete in the concrete pump hopper shall be continuously stirred, and the height of the concrete in the hopper shall not be lower than that when the concrete is pumped400.
7, the concrete conveying pump pipe should be kept level, when long distance pumping, the pump pipe should be solid.
8, when the temperature is higher than30℃When, it is appropriate to cover the heat insulation material on the conveying pump pipe, and every other period of time should be sprayed to cool down.
9After drilling to design elevation, concrete should be pumped in and stopped10～20sAnd then slowly lift the drill pipe. The lifting speed should be determined according to the soil layer, and should be matched with the concrete pumping quantity to ensure that there is a certain height of concrete in the pipe.
10When drilling in the sand layer below the water table, the valve at the bottom of the drill pipe should be taken to prevent water intake, and the concrete should be continuously pressed.
11, the filling coefficient of the pressure grouting pile should be1.0～1.2. The overpouring height of concrete at pile top should not be less than0.3～0.5m.
12After piling, the residual concrete in the drill pipe and pump (soft) pipe should be removed in time. When stopping for a long time, clean water should be used to clean the drill pipe, pump pipe and concrete pump.
13After the concrete pressure irrigation, the reinforcement cage should be inserted to the design depth immediately. The special inserting device should be used for reinforcing cage insertion.
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