CN209798792U - open cut foundation pit deep silt layer vacuum dewatering system - Google Patents

Abstract

the utility model discloses an open cut basement deep silt layer vacuum dewatering system and construction method, including the precipitation well, the precipitation well degree of depth is 26 ~ 34m, and the well in-process meets cubic efflorescence or during the unable footage of apoplexy, can make the well in advance the final hole, and the mud aperture is 550mm, adopts diameter 273mm, wall thickness 3mm steel pipe, and the chimney filter is the bridge type strainer, outsourcing 80 mesh polyamide fibre filter screen, has set 1m sedimentation tube, and the filter material is above backfilling the chimney filter, adopts to bore sediment or original place soil to backfill the well cementation on it. The utility model relates to an open cut foundation ditch deep silt layer vacuum dewatering system and construction method, under the thick geological conditions in sea-filling mud flat silt layer, adopt the effectual safety and the efficiency that have guaranteed foundation ditch excavation of having improved dewatering effect of vacuum dewatering. Compared with the conventional precipitation, the precipitation period is shortened by adopting vacuum precipitation, the influence of transition precipitation on the peripheral earth surface and buildings can be prevented, the risk caused by foundation pit excavation precipitation is reduced, and meanwhile, the construction cost is also saved.

Description

Open cut foundation pit deep silt layer vacuum dewatering system

Technical Field

the utility model relates to a construction technical field, concretely relates to open cut basement is silt layer vacuum dewatering system deeply.

Background

In the excavation construction of the underground deep foundation pit with higher underground water level and confined water, in order to ensure the safety of the excavation of the foundation pit, particularly in the areas with large water content and large pressure bearing, the deep foundation pit needs to be subjected to precipitation design and construction. According to the scheme, the construction design and construction of deep foundation pit dewatering are carried out under the condition that most of geology of the sea-filling area of the open excavation section between the Shenzhen international convention and exhibition center is a silt layer, and related experiences are summarized so as to guide the dewatering construction under the similar conditions and improve the technical level of the dewatering construction of companies.

SUMMERY OF THE UTILITY MODEL

the utility model aims at providing a deep silt layer vacuum precipitation system of open cut foundation pit that displacement is big, the precipitation degree of depth is big, the precipitation scope is big.

In order to achieve the above object, the present invention provides the following technical solutions:

the utility model discloses an open cut basement dark silt layer vacuum precipitation system, include:

dewatering wells;

the number of dewatering wells is calculated according to the following formula:

In the formula: q is total water inflow (m3/d), Q is single well water output capacity (m3/d), and 20% of standby observation wells;

the depth of the dewatering well is 26-34 m, when the well is subjected to massive strong weathering or stroke weathering in the well forming process and cannot be drilled, the well can be formed in a final hole in advance, the aperture of mud is 550mm, a steel pipe with the diameter of 273mm and the wall thickness of 3mm is adopted, a bridge type water filtering pipe is adopted as a filtering pipe, an 80-mesh nylon filter screen is wrapped outside the filtering pipe, a 1m settling pipe is arranged below the filtering pipe, the filtering material is filled above a backfill filtering pipe, and drilling slag or original stratum soil is adopted for backfill well cementation.

Further, the water yield of a single well of the dewatering well is calculated according to the following formula:

in the formula: q-single well water output capacity (m 3/d); r-radius of filter tube (0.1365 m); l-effective filter tube length, 6 m; k-permeability coefficient of the aquifer (0.2 m/d).

in the technical scheme, the utility model relates to an open cut foundation ditch deep silt layer vacuum precipitation system and construction method under the thick geological conditions in sea-filling mud flat silt layer, adopts the effectual safety and the efficiency that have guaranteed the foundation ditch excavation of having improved precipitation effect of vacuum precipitation. Compared with the conventional precipitation, the precipitation period is shortened by adopting vacuum precipitation, the influence of transition precipitation on the peripheral earth surface and buildings can be prevented, the risk caused by foundation pit excavation precipitation is reduced, and meanwhile, the construction cost is also saved.

drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the present invention, and other drawings can be obtained by those skilled in the art according to these drawings.

fig. 1 is a schematic structural diagram of a first vacuum dewatering system for a deep silt layer of an open trench foundation pit according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a vacuum dewatering system for a deep silt layer of an open trench provided in an embodiment of the present invention;

fig. 3 is a third schematic structural view of a vacuum dewatering system for a deep silt layer of an open trench provided in an embodiment of the present invention;

Fig. 4 is a process flow chart of the vacuum dewatering system for the deep silt layer of the open excavation foundation pit provided by the embodiment of the utility model.

Detailed Description

in order to make the technical solution of the present invention better understood by those skilled in the art, the present invention will be further described in detail with reference to the accompanying drawings.

the first embodiment is as follows:

referring to fig. 1 to 3, an embodiment of the present invention provides a deep silt layer vacuum precipitation system for an open trench foundation pit, including:

Dewatering wells;

the number of dewatering wells is calculated according to the following formula:

in the formula: q is total water inflow (m3/d), Q is single well water output capacity (m3/d), and 20% of standby observation wells;

The depth of the dewatering well is 26-34 m, when the well is subjected to massive strong weathering or stroke weathering in the well forming process and cannot be drilled, the well can be formed in a final hole in advance, the aperture of mud is 550mm, a steel pipe with the diameter of 273mm and the wall thickness of 3mm is adopted, a filter pipe is a bridge type water filter pipe, an 80-mesh nylon filter screen is wrapped outside, a 1m settling pipe is arranged below the filter pipe, the filter material is filled to a position above a backfill filter pipe, and drilling slag or original stratum soil is used for backfilling and well cementation.

Preferably, the single-well water yield of the dewatering well is calculated according to the following formula:

In the formula: q-single well water output capacity (m 3/d); r-radius of filter tube (0.1365 m); l-effective filter tube length, 6 m; k-permeability coefficient of the aquifer (0.2 m/d).

example two:

the utility model discloses a construction method of open cut foundation pit deep silt layer vacuum dewatering system, including following step:

s1, preparing;

s2, entering a drilling rig;

s3, positioning and mounting;

S4, opening holes;

s5, a lower mouth guard pipe;

S6, drilling to form a hole;

S7, punching and replacing the slurry;

S8, a well descending pipe;

S9, diluting the slurry;

S10, filling sand;

S11, sealing water and holes;

s12, washing the well;

and S13, taking down the pump for trial pumping.

preferably, in step S1 above:

(1) preparing materials and implementing personnel, providing 'tee joint and level' for the final package, and entering a drilling machine;

(2) Measuring the well placement: and marking the general packet according to a dewatering well plane arrangement diagram and the field condition well logging position. If there is a surface obstruction at the deployed well site, it should be attempted to clear the obstruction to facilitate drilling. If the ground obstacles are not easy to clear or are influenced by other construction conditions, and the construction cannot be carried out at the original distributed well position, the ground obstacles should be communicated with a technician in time and take other measures, and the well position can be properly adjusted if necessary;

(3) Digging a well hole and burying a mouth protecting pipe: when the mouth protecting pipe is buried, the bottom mouth of the mouth protecting pipe is inserted into an undisturbed soil layer, cohesive soil or a straw braid is applied outside the pipe for sealing, the slurry return outside the pipe during construction is prevented, and the upper part of the mouth protecting pipe is 0.10-0.30 m higher than the ground;

(4) Installing a drilling machine: when a drilling machine is installed, in order to ensure the verticality of a hole, a machine table is installed stably and horizontally, a large hook is aligned with the center of the hole, the large hook, a rotary table and the center of the hole form a line, an opening is tightly closed, two drill collars are arranged at the joint of a drill bit and a drill rod, and the bent drill rod cannot be put into the hole;

(5) and (3) dredging a slurry pool: the size of the mud pit is comprehensively determined according to the well-digging quantity and the slag discharge quantity which are planned to be shared by the mud pit. Generally, 2-3 wells share one mud pit, and a mud tank can be adopted when necessary.

preferably, the construction mechanical equipment adopts a GF200 type engineering drilling machine and matched equipment thereof, and a reverse circulation rotary drilling hole forming process is adopted during hole forming;

(1) drilling to form a hole: in the drilling process, the specific gravity of the slurry is preferably controlled to be 1.10-1.15, and the formation is adopted to make slurry naturally as much as possible;

(2) cleaning holes and replacing slurry: after drilling to the designed depth, cleaning the hole and changing slurry, and adjusting the slurry to about 1.05;

(3) a well pipe is lowered: for the steel pipe well, a suspension pipe descending method is preferably adopted, the bottom of the well pipe is firmly blocked by welding a steel plate, the well pipe and the well pipe are firmly welded, the welding seam is ensured to be uniform and free of sand holes, and the pipe is immediately descended after the pore-forming is finished;

(4) feeding filter materials and cementing wells: after the well pipe is well lowered, the filter material is immediately backfilled according to the design requirement, the filter material is uniformly filled along the periphery of the well wall, and the height of the top surface of the filter material layer is measured along with the filling;

(5) Well washing and trying pumping: after the filter material is backfilled, the well should be washed by a submersible pump within 8 hours until the well water washing reaches the specification requirement. If the well water contains filter materials during well washing, the well washing is stopped, reasons are checked, the well washing is processed, the well washing is discarded if necessary, and the well is sealed according to the well sealing requirement.

according to the technical scheme, the blank of the construction technology of the company in the aspect is filled by summarizing the vacuum dewatering technology of the deep silt layer of the open excavation foundation pit of the sea-filling area, and a technical guidance direction is provided for similar projects of the company later, so that corresponding manpower and material resources are reduced.

the design of the precipitation construction scheme is comprehensively beneficial to reducing potential risks, improving construction efficiency, showing the technical level of technicians of the company to other persons and units in the industry and reducing the remediation cost of possible problems in the follow-up process, thereby reducing production cost.

due to the fact that a refined management mode is adopted in the dewatering well construction project, the method is beneficial to enhancing the utilization of resources, reducing the waste of the resources, further improving the management level and responsibility consciousness of managers, and establishing specialized teams which belong to the managers, so that the enterprise competitiveness of the managers is further improved.

The sea-filling area has rich water content, natural water content is generally greater than liquid limit, geology is mostly soft foundation, once stratum water level changes greatly, ground settlement is easily caused, and therefore the use performance of the building is affected, and therefore the research on the vacuum precipitation technology of the sea-filling area is necessary. Through the research on the vacuum precipitation technology of the deep silt layer of the open-cut foundation pit of the sea-filling area, the influence of earthwork construction on the surrounding environment, particularly the ground settlement of the surrounding area, can be reduced, so that the compensation cost of surrounding buildings is reduced, and the project benefit is maximized.

while certain exemplary embodiments of the present invention have been described above by way of illustration only, it will be apparent to those of ordinary skill in the art that the described embodiments may be modified in various different ways without departing from the spirit and scope of the present invention. Accordingly, the drawings and description are illustrative in nature and should not be construed as limiting the scope of the invention.

Claims (2)

1. The utility model provides an open cut foundation ditch deep silt layer vacuum precipitation system which characterized in that includes:

dewatering wells;

the number of dewatering wells is calculated according to the following formula:

in the formula: q is total water inflow (m3/d), Q is single well water output capacity (m3/d), and 20% of standby observation wells;

the depth of the dewatering well is 26-34 m, when the well is subjected to massive strong weathering or stroke weathering in the well forming process and cannot be drilled, the well can be formed in a final hole in advance, the aperture of mud is 550mm, a steel pipe with the diameter of 273mm and the wall thickness of 3mm is adopted, a bridge type water filtering pipe is adopted as a filtering pipe, an 80-mesh nylon filter screen is wrapped outside the filtering pipe, a 1m settling pipe is arranged below the filtering pipe, the filtering material is filled above a backfill filtering pipe, and drilling slag or original stratum soil is adopted for backfill well cementation.

2. The open cut foundation pit deep sludge layer vacuum dewatering system of claim 1, wherein the water yield of the dewatering well is calculated according to the following formula:

In the formula: q-single well water output capacity (m 3/d); r-radius of filter tube (0.1365 m); l-effective filter tube length, 6 m; k-permeability coefficient of the aquifer (0.2 m/d).