(3) Organize personnel to conduct technical disclosure.
Part I open ditch plus water collecting well dewatering I.
key quality control points and inspection standards 1.
Key quality control points (1) clear water or mud drilling and high-pressure water casing impact technology (drilling method, punching method or water jet method) can be selected for the drilling process of vacuum well points and jet well points, and long screw drilling machine can also be selected for the formation that is not easy to collapse and shrink holes; The hole forming depth should be 0.5m ~ 1.0m greater than the design depth of dewatering well..
(6) The strength of the filter pipe shall meet the requirements, and the winding filter screen shall be tight to prevent the sand content of the outlet water from exceeding the standard.
In case of failure of well pipe, measures shall be taken to restore it to normal.
The particle size of filter material shall not be too large, and the filler thickness shall not be less than the design requirements.
process flow IV.
It is strictly prohibited to forcibly insert the well pipe into the bottom of the precipitated hole.
Foundation pit dewatering and drainage construction foundation pit dewatering and drainage refers to the dewatering work done to ensure that the foundation pit can be constructed under dry conditions and prevent slope instability, foundation quicksand, pit bottom uplift, pit bottom piping and foundation bearing capacity decline when the groundwater level is higher than the excavation bottom when excavating the foundation pit.
(4) When the dewatering well needs to be cut off and tested with the excavation depth of the foundation pit, the filter material layer 1m below the ground around the well pipe shall be removed for the dewatering well that continues to operate, and the well shall be sealed with clay before operation.
(7) The sediment volume after well flushing shall be controlled within 10%.
（2） Material preparation well pipe, fine gravel, gravel, clay and drainage pipe.
(3) Organize personnel to conduct technical disclosure.
Construction preparation (I) technical preparation (1) be familiar with the construction drawings, engineering survey data and geological conditions, and understand the groundwater level and soil permeability coefficient; The well point dewatering design shall be carried out according to the foundation pit form, excavation support design, dewatering depth, dewatering range, dewatering time, engineering environmental impact, etc.
(3) Organize personnel to conduct technical disclosure.
When running the pipe, the well pipe shall be vertical in the center and firmly connected.
The filter material can be put into operation only when the specific gravity of the mud is not greater than 1.05; In case of hole collapse, the well pipe shall not be placed, and the filling volume of filter material shall not be less than 95% of the calculated amount; (3) After the filter material is filled, the well shall be washed in time.
(2) According to the actual situation of the site, draw the plan layout of well points, the structural drawing of dewatering facilities, the plan and profile of dewatering water level prediction curve, prepare the special construction scheme for dewatering and drainage, and carry out the construction after review and demonstration according to the procedure.
The removal and connection of power cables during construction must be undertaken by professionals.
If it is impossible to recover, it shall be scrapped and a new well pipe shall be set; The pumping control time for commissioning is 1D, and the water quality and water output shall be checked.
preparation basis II.
(3) Check the water level in the observation well at any time during precipitation, and adjust the pumping speed and amount.
preparation basis II.
The well shall be washed fully until the filter and filter material filter water are unblocked, and water shall be pumped to test the water filtering effect of the dewatering well.
Key points of quality control (1) the hole forming construction process of pipe well shall be suitable for the formation characteristics, and clear water drilling shall be adopted for the formation that is not easy to collapse and shrink; The drilling depth should be 0.3m ~ 0.5m greater than the design depth of dewatering well; (2) When mud is used for wall protection, the sediment at the bottom of the hole shall be removed after drilling to the bottom of the hole, and the well pipe shall be placed immediately and clean water shall be injected.
（3） Preparation of machines and tools III.
（2） Material preparation: coarse sand and filter screen.
key points of construction v.
The comparison of various dewatering methods is shown in the table below: open ditch plus collecting well dewatering, pipe well point dewatering, light well point dewatering and drainage of drainage well commonly used in engineering construction.
Common precipitation methods include: open ditch plus collecting well precipitation, light well point precipitation, jet well point precipitation, electroosmosis well point precipitation, tube well point precipitation, etc.
key points of quality control and inspection standards 1.
(2) Formal pumping should be carried out 3 days after trial pumping; The dewatering well should be operated 20 days before the foundation pit excavation.
key points of construction v.
(2) According to the actual situation of the site, draw the plan layout of well points, the structural drawing of dewatering facilities, the plan and profile of dewatering water level prediction curve, prepare the special construction scheme for dewatering and drainage, and carry out the construction after review and demonstration according to the procedure.
2.
See the following table for the acceptance criteria for the construction quality of pipe well dewatering: Part III light well point dewatering I.
preparation basis II.
（3） Preparation of machines and tools III.
（3） Prepare other equipment and materials for machines and tools: casing, air compressor and vacuum gauge.
Construction preparation (I) technical preparation (1) be familiar with construction drawings, engineering survey data and geological conditions, and understand groundwater level and soil permeability coefficient; The well point dewatering design shall be carried out according to the foundation pit form, excavation support design, dewatering depth, dewatering range, dewatering time, engineering environmental impact, etc.
Construction preparation (I) technical preparation (1) be familiar with construction drawings, engineering survey data and geological conditions, and understand groundwater level and soil permeability coefficient; The well point dewatering design shall be carried out according to the foundation pit form, excavation support design, dewatering depth, dewatering range, dewatering time, engineering environmental impact, etc.
(2) The well location of each dewatering well shall form a closed shape at a certain distance along the periphery of the foundation pit.
Key points for operation of dewatering system (1) the dewatering system shall be subject to trial operation.
(5) The logging depth of well tool shall be used for each well drilled to ensure that the deviation of well depth is ≤ 20cm.
(4) Before laying the pipe, check whether there are sundries and clay inside and outside the pipe to prevent affecting the water permeability.
key points of quality control (1) open drainage in foundation pit shall be provided with drainage ditch and collecting well, and the longitudinal slope of drainage ditch shall be controlled at 1 ‰ ~ 2 ‰.
(2) According to the actual situation of the site, draw the plan layout of well points, the structural drawing of dewatering facilities, the plan and profile of dewatering water level prediction curve, prepare the dewatering and drainage construction scheme, and carry out the construction after review and demonstration according to the procedure.
key construction points v.
(3) During foundation pit dewatering, generator sets shall be equipped according to the construction organization design, and corresponding power supply switching drills shall be carried out.
process flow diagram of dewatering with open ditch and collecting well IV.
Part II pipe well dewatering I.
（2） Material preparation: lime sand brick, mortar, gravel and drainage pipe.
3、 Process flow IV.
