CN115217133A

CN115217133A - Construction process of foundation pit drainage system in coastal region

Info

Publication number: CN115217133A
Application number: CN202210907591.5A
Authority: CN
Inventors: 杨璠; 周霞菊
Original assignee: Shanghai Baoye Group Corp Ltd
Current assignee: Shanghai Baoye Group Corp Ltd
Priority date: 2022-07-29
Filing date: 2022-07-29
Publication date: 2022-10-21

Abstract

The invention discloses a construction process of a coastal region foundation pit drainage system, which comprises the following steps: selecting a pipeline: the buried pressure sewage pipe adopts a steel wire mesh skeleton polyethylene composite pipe; various drainage structures are all of reinforced concrete structures; then measuring and paying off, excavating a foundation trench, installing a pressure sewage pipeline, installing a reinforced concrete rabbet pipe, installing an HDPE winding reinforced B-shaped pipe, performing interface leakage-proof treatment, and performing a tightness test after the pipeline is installed; backfilling the groove after the test is qualified, then installing a submersible sewage pump, and installing rainwater pump room equipment; constructing a concrete structure, finally removing a mold, maintaining, and backfilling and tamping after the strength of the concrete structure reaches the designed strength; the invention has scientific method, low cost, good drainage effect, no water leakage, stable structure and long service life.

Description

Construction process of foundation pit drainage system in coastal region

Technical Field

The invention belongs to the technical field of drainage, and particularly relates to a construction process of a foundation pit drainage system in a coastal region.

Background

With the release of 'water pollution control action plans' (namely ten water programs) by the country, one of the very important ones is the treatment of water environment and sewage in the coastal harbor area, and the drainage system of the whole coastal area comprises: rainwater, sewage pipe systems; rain sewage inspection wells, ditch pipe connecting wells, sewage lifting wells, pressure sewage inspection wells, rainwater box culverts and other underground drainage small structures. Mainly aims at dock ballast water, clean rainwater in storage yard, machine maintenance oil sewage, tank washing water and domestic sewage generated by buildings.

The drainage system adopts a split system, and the main mode of rainwater drainage adopts a rainwater pipeline; clean rainwater in a storage yard is collected by an open ditch and a closed pipe and then is discharged into a rainwater pump room, and is discharged by gravity flow in the low tide of the Yangtze river and is discharged by a submersible axial flow pump in the high tide. Domestic sewage is collected through the concealed conduit, and is connected to a municipal sewage pipe network after being lifted by a sewage lifting pump, so that the system is not economical.

Traditional drainage system causes ponding more easily when the yard ground is uneven subsides, and the drainage effect is relatively poor, and drainage facility cost is high, and later maintenance management is inconvenient, has not accorded with the requirement of new standard, needs the improvement.

Disclosure of Invention

In order to solve the problems, the invention discloses a construction process of a foundation pit drainage system in a coastal region, which has the advantages of scientific method, low manufacturing cost, good drainage effect, no water leakage, stable structure and long service life.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a construction process of a foundation pit drainage system in a coastal region comprises the following steps:

(1) Selecting materials: the diameter of the buried drain pipe is less than 1500mm, and a B-shaped pipe is wound and enhanced by adopting HDPE; the pipe diameter is more than or equal to 1500mm, and a reinforced concrete rabbet pipe is adopted; the buried pressure sewage pipe adopts a steel wire mesh skeleton polyethylene composite pipe; various drainage structures are all of reinforced concrete structures;

(2) And (3) measurement and paying-off: before the pipeline trench is excavated, measuring a horizontal point and a pipeline axis of the pipeline according to the reference point, and arranging a control pile which is convenient to observe and firm;

(3) Excavating a foundation trench: the depth of the groove is determined according to the elevation of the bottom of the pipeline designed by the construction drawing and the actually measured elevation of the ground of the original soil; the excavation depth is 2-4.8 m; longitudinally arranging drainage ditches at two sides in the base groove, wherein the width of each drainage ditch is 20cm, the depth of each drainage ditch is 20-30cm, water collecting wells with the size of 1m × 1m are arranged at intervals of 20-30m, the longitudinal gradient of each drainage ditch is the same as that of each groove, the water collecting wells are lower than the bottoms of the drainage ditches by 50cm, all the submersible pumps are submerged in water, and the water is pumped to adjacent rainwater wells through the water pumps;

(4) Installing a pressure sewage pipeline;

(5) Installing a reinforced concrete rabbet pipe; the pipeline foundation comprises a gravel cushion layer, a concrete cushion layer and a concrete foundation;

paving a broken stone cushion layer at the bottom of the groove, tamping the broken stone cushion layer by using a flat plate vibration tamper, measuring a central line after tamping and leveling, and reserving a sedimentation amount; c15 concrete is adopted as a pipeline concrete cushion layer and is paved above the gravel cushion layer, and C20 concrete is adopted as a pipeline concrete foundation and is poured on the pipeline;

the pipeline hoisting adopts a sectional type pipe lowering, namely, the reinforced concrete rabbet pipes are respectively hoisted one by one and then are lowered into the grooves for assembly; adopting a rubber sealing ring for connection; finally, when the connector is installed in a jacking mode, a portal frame is adopted, a steel wire rope is tied on the stably installed pipeline during matching, a back beam is erected at the position of a pipeline socket to be pulled in, the steel wire rope and the chain blocks are connected to be tightened and aligned, the chain blocks are synchronously pulled on two sides, and the socket with the rubber ring sleeved is pulled into the rabbet after being hit;

(6) Installing an HDPE winding reinforced B-shaped pipe, laying pipes in the groove, connecting the pipes by adopting socket electrothermal welding, and preheating the pipes with DN900 and above for 2min before welding; the pipeline is connected with the inspection well by a short pipe, a pipeline socket is arranged in the water inlet direction of the inspection well, and a pipeline socket is arranged in the water outlet direction of the inspection well;

(7) Interface leak-proof treatment:

to the interface processing of concrete pipe, except rubber seal, additionally increase wire net cement mortar daubing area and geotechnological cloth parcel twice safeguard measure again, concrete measure is:

asbestos cement is used for sealing the inside and the outside of the reinforced concrete pipe joint; the outer wall is plastered with 1;

before backfilling the pipeline, the use amount is more than or equal to 250g/m ² Nonwoven geotextile bagWrapping a pipeline interface; the circumferential direction lap length is 500mm;

the HDPE winding reinforced B-shaped pipe is connected by electric hot melting and is used for being more than or equal to 250g/m ² Wrapping the pipeline connector with the non-woven geotextile;

the joint of the pipeline and the well is filled with oil-immersed hemp threads, the inner opening is filled with 1:2 cement mortar, the outer opening is filled with asbestos cement, and corners are plastered by 1:2 cement mortar; then a layer of more than or equal to 250g/m is wrapped ² Non-woven geotextile;

(8) Performing a tightness test after the pipeline is installed;

(9) Backfilling the groove after the test is qualified

Tamping the reinforced concrete pipeline in a range from the pipe bottom foundation to 0.8m above the pipe top and tamping the HDPE reinforced winding B-shaped pipeline in a range from the pipe bottom foundation to 1m above the pipe top by using a frog tamper or a plate tamper, wherein the backfill soil is undisturbed soil;

(10) The submersible sewage pump is fixedly installed, an automatic coupling device, a control cabinet and a water level controller are matched with the water pump, and the submersible sewage pump is automatically started and stopped according to the water level;

(11) Mounting rainwater pump room equipment;

(12) Construction of a concrete structure: the concrete structure comprises a rainwater inspection well, a sewage inspection well, a trench pipe connecting well and a pressure sewage inspection well, wherein the detailed position, gradient and depth of the inspection well are measured by measuring personnel, a foundation pit is dug, one layer of well point dewatering is arranged within 3m of the excavation depth, and two layers of well point dewatering are arranged within 3-5m of the excavation depth;

the slope of foundation ditch excavation is decided according to engineering actual conditions, adopts 1 within 3 m: 0.75,3-5m adopts 1:1, and can adopt temporary support measures of steel pipes, wood plates, and bamboo fence;

and then binding steel bars, supporting templates, pouring concrete, vibrating, removing the templates, maintaining, and beginning to backfill and tamp after the strength of the concrete structure reaches the designed strength.

Step (3), adopting one-time slope-releasing excavation within 3m of the depth of the groove, wherein the gradient is 1.0 or the gradient is properly reduced according to the soil property; the depth of the groove is larger than 3m, a grading transition platform is arranged, the width of the platform is the operation width of the excavator, and the grading excavation gradient is 1.0, and the grading transition platform can also be properly adjusted.

And (3) corresponding drainage measures are required in the trench excavation process, so that the concrete is not soaked in water before reaching the designed strength, the excavation surface is properly expanded during construction, and the excavation length is shortened as much as possible, wherein each 30m is one section. And for the part with small excavation depth and low underground water level, arranging a drainage open trench and a water collecting pit in the trench, if underground water seeps out, enabling the underground water to flow to the drainage open trench and then to be collected to the water collecting pit, and then pumping away by using a centrifugal water pump.

Adopting C20 concrete for the pipeline concrete foundation, pouring for 2 times, pouring for the first time to the pipe bottom elevation, and then installing a pipeline; after the pipeline is installed, pouring the rest part;

in the step (5), all impurities in the bell and spigot are firstly removed and cleaned, and then non-oily lubricant is uniformly smeared in the tongue and groove; uniformly coating a non-oily lubricant on the surface of the rubber sealing ring; bending the rubber sealing ring into a heart shape or a flower shape, loading the rubber sealing ring into the groove, and pressing the rubber sealing ring once along the whole rubber sealing ring by hand to ensure that all parts of the rubber sealing ring are not warped and twisted and are uniformly and uniformly clamped in the groove; the rubber ring is positioned on the tongue-and-groove working surface after being positioned.

And (5) connecting the HDPE pipes in the step (6) by socket-and-spigot electrothermal welding, wherein the connection is guided by professional personnel of a manufacturer to operate. The pipeline with the diameter less than DN400mm is characterized in that firstly, one person uses a hemp rope to hang a socket of the pipe B, the other person uses a long prying bar to insert the pipe B into the foundation in an inclined mode and supports against a transverse baffle plate at the center of the end part of the pipeline, and then the pipe B is forcibly and slowly inserted into a socket of the pipe A to a preset position; the pipeline with the DN being 400mm can be pulled to be in place by 2 0.50-ton chain blocks, and when the connector is closed, the chain blocks on the two sides of the pipeline section are pulled synchronously; in order to prevent the axial line position of the pipeline arranged firstly from moving when the connector is closed, a pipe stabilizing measure is required, and the specific method can fill yellow sand in the woven bag, seal the woven bag and press the top of the pipeline arranged firstly.

The compaction process for backfilling the reinforced concrete pipeline groove in the step (9) comprises the following steps:

1. backfilling and compacting are carried out layer by layer, and the layering thickness is 200mm;

2. in the real-time segmented backfill, the connecting stubbles of adjacent segments are in a step shape;

3. tamping by adopting a frog rammer or a plate rammer light compaction device;

4. the trench backfilling is carried out symmetrically from two sides at the same time;

the compaction process for backfilling the groove of the HDPE reinforced winding B-shaped pipe comprises the following steps:

1. the inner diameter of the pipe is larger than 800mm, and a vertical support is arranged in the pipe during backfilling construction;

2. when backfilling below the radius of the pipeline, measures for preventing the pipeline from floating and displacing are taken;

3. and backfilling the pipeline from two sides of the pipeline simultaneously and tamping the pipeline simultaneously.

In the tamping process in the step (9), if the soil is sandy soil, a watertight method is adopted for auxiliary compaction: firstly, backfilling 200mm sandy soil, leveling, and then uniformly injecting water into a backfill soil layer, wherein the water injection amount is based on no open water on the surface layer, so that the backfill soil reaches the saturated water content; and after standing for 5-20min, tamping the backfill soil by small compaction equipment of a frog rammer or a plate rammer.

Step (10), a submersible sewage pump installation step:

1. installing a guide rod and a pump seat: lifting the pump base, descending to the foundation, enabling the bolt holes in the pump base to be over against foundation bolts embedded in the foundation, leveling the pump base by using a horizontal ruler, and then screwing down the foundation bolts; the bottom of guide arm is connected with the pump mount, and the top is connected with the support frame.

2. Mounting the pump body: and hoisting the pump body, placing the coupling device into the guide rod, and enabling the pump body to descend along the guide rod until the coupling device is connected with the water outlet bent pipe on the pump seat.

The invention has the beneficial effects that:

the construction process of the coastal region foundation pit drainage system is scientific, low in manufacturing cost, good in drainage effect, watertight, stable in structure and long in service life.

Drawings

FIG. 1 is a process flow diagram of the present invention;

FIG. 2 is a sectional view of the excavation of the foundation trench according to the present invention;

FIG. 3 is a schematic view of the open trench and sump drainage of the foundation trench according to the present invention;

FIG. 4 is a schematic view of a concrete pipe installed by a chain block pull-in method according to the present invention;

FIG. 5 is a schematic view of a concrete pipe joint process according to the present invention;

FIG. 6 is a schematic view of a pipe according to the present invention connected to a well;

FIG. 7 is a schematic view of the operation of the watertight method according to the present invention;

FIG. 8 is a schematic view of a submersible sewage pump according to the present invention;

FIG. 9 is a process flow diagram of the rainwater pump house according to the present invention;

fig. 10 is a sectional view of a foundation pit excavation of a concrete structure of various wells according to the present invention.

Detailed Description

The present invention will be further illustrated with reference to the accompanying drawings and specific embodiments, which are to be understood as merely illustrative of the invention and not as limiting the scope of the invention.

Taking XX coastal area stage X project as an example, the construction content of the project drainage system comprises: rainwater, sewage pipe systems; rain sewage inspection shaft, ditch union coupling well, sewage lifting shaft, pressure sewage inspection shaft, rainwater box culvert etc. underground drainage small-size structures.

The drainage system adopts a split system, and mainly comprises wharf ballast water, yard clean rainwater, machine maintenance oily sewage, tank washing water and domestic sewage generated by buildings.

The main mode of rainwater drainage of the invention adopts a rainwater pipeline. Clean rainwater in a storage yard is collected by an open ditch and a concealed pipe and then discharged into a rainwater pump room, is discharged by gravity flow in the low tide of the Yangtze river, is discharged by a submerged axial-flow pump in the high tide, and is lifted by a sewage lifting pump and then is connected into a municipal sewage pipe network after being collected by a concealed pipe.

The construction process comprises the following steps:

1. pipe selection

The buried drain pipe has a pipe diameter less than 1500, and is formed by winding and reinforcing a B-shaped pipe by using HDPE (high-density polyethylene) and connecting a spigot-and-socket rubber sealing ring; the pipe diameter is more than or equal to 1500, and is connected by a reinforced concrete (II) pipe (a tongue-and-groove pipe) and a rubber sealing ring. The buried pressure sewage pipe is a steel wire mesh skeleton polyethylene composite pipe (the pressure grade is 1.6 MPa) and is connected by electric melting. (various drainage structures adopt reinforced concrete structures).

The selected pipe material must meet the requirements of the national current product industry standard and technical standard. The ring stiffness of HDPE drainpipes must be equal to or greater than 10KN/m2.

2. Measuring pay-off

The pipeline is installed in a storage yard and begins to be constructed after the road rolling is finished. Before the pipeline trench is excavated, a horizontal point and a pipeline axis of the pipeline are measured according to the reference point, and a control pile which is convenient to observe and firm is arranged.

3. Excavation of foundation trench

Groove type

The project is a new project, the peripheral ground is wide, no building exists nearby, the soil quality is mainly the filling soil after foundation treatment according to the geological report, a small amount of sticky silt is good, and the excavation depth is 4.8m deepest. Therefore, a construction scheme of slope enlarging and excavation is adopted.

Cross section of groove

According to GB50268-2008 'construction and acceptance criteria for water supply and drainage pipeline engineering', the excavation width of the bottom of the groove is required to meet the design requirement; when the design is not required, the design can be calculated and determined according to the following formula;

B=D ₀ +2(b ₁ +b ₂ +b ₃ )

b in the formula is the excavation width (mm) of the bottom of the pipeline groove;

D ₀ -tube outside diameter (mm);

b ₁ -the width of the working surface on one side of the pipe (mm);

b ₂ -when support is required, the support thickness of one side of the duct may be 150-200 mm;

b ₃ -casting a side template of a concrete or reinforced concrete pipe duct in situ to form a thickness (mm).

Therefore, the width of the base groove of the drainage pipeline with each specification in the project can be calculated as follows (the base width of the concrete pipeline is taken as D0):

table 1 pipeline foundation trench excavation width meter

The depth of the groove is determined according to the elevation of the bottom of the pipeline designed by the construction drawing and the actually measured elevation of the ground of the original soil. The excavation depth is 2-4.8 m.

According to GB50268-2008 'construction and acceptance criteria for water supply and drainage pipeline engineering', once slope excavation is adopted within 3m of the depth of a groove, the slope is 1.0, or the slope is properly reduced according to soil texture; the depth of the groove is larger than 3m, a grading transition platform is arranged, the width of the platform is the operation width of the excavator, the grading excavation gradient is 1.0, and the grading transition platform can also be properly adjusted, as shown in fig. 2.

Excavation of foundation trench

The engineering adopts a step (layer) excavation method of 2 excavators, one excavator excavates a foundation trench, the other excavator loads earthwork excavated by the first excavator, and the earthwork is refueled to a safe position of the foundation trench. And well drainage and well point dewatering are well carried out before the excavation.

The excavator for the engineering excavates to the height of 300mm above the ground surface, and the surplus soil with the thickness of 300mm is excavated manually.

Drainage ditches are longitudinally arranged on two sides in the base groove, the width of each drainage open ditch is 20cm, the depth of each drainage open ditch is 20-30cm, water collecting wells with the size of 1m × 1m are arranged every 20-30m, the longitudinal gradient of each drainage ditch is the same as that of each drainage ditch, and the water collecting wells are lower than the bottoms of the drainage ditches by 50cm so as to ensure that the submersible pumps can be completely submerged into water, and the water is pumped to adjacent rainwater wells through the water pumps. During the rain-free period, the water level in the water collecting well exceeds the water level of the drainage ditch, the submersible pump is started immediately to pump out the accumulated water in the well until the water level in the water collecting well is lower than the bottom of the drainage ditch, and the water pumping can be stopped. During raining, water should be pumped uninterruptedly, and the water level in the well is guaranteed to be lower than the water level in the drainage ditch all the time.

Considering that the underground water level of a storage yard is high, corresponding drainage measures are required for trench excavation, the concrete is not soaked in water before the designed strength is achieved, the excavation surface can be properly expanded during construction, the excavation length is shortened as much as possible, and each 30m section is a section. For the part with small excavation depth and low underground water level, a drainage open ditch and a water collecting pit are arranged in the groove, if underground water seeps out, the underground water flows to the drainage open ditch and then is collected to the water collecting pit, and then the part is pumped by using a centrifugal water pump, as shown in figure 3.

4. Pressure sewer piping installation

The pressure sewage pipeline adopts a steel wire mesh framework polyethylene composite pipe, and the construction process is basically the same as that of a water supply pipeline and a fire fighting pipeline;

5. concrete pipe installation

Pipeline foundation

The pipeline foundation comprises a gravel cushion layer, a concrete cushion layer and a concrete foundation.

And paving a gravel cushion layer with a specified thickness at the bottom of the tank, and tamping by using a flat plate vibration tamper. And after the materials are tamped and leveled, measuring the central line, and reserving the settling volume. The width of the mat must be tightly controlled to ensure the angle of the pipe wrap.

The pipeline concrete cushion layer is made of C15 concrete after paving of the gravel cushion layer is completed, and the width and the thickness of the cushion layer must be strictly controlled.

The pipeline concrete foundation adopts C20 concrete, is poured for 2 times, is poured to the pipe bottom elevation for the first time, and then is installed with a pipeline. And after the pipeline is installed, pouring the rest part.

Pipeline hoist and mount

The engineering crane adopts a sectional type pipe laying process, namely, a pipe is respectively hoisted one section by one section and then is laid into the groove to be assembled.

After the pipeline is laid in the ditch, the axis of the pipeline is coincided with the central line of the pipe ditch, a total station is adopted to control the coordinate of each section of pipeline, the transverse deviation of the pipeline is in accordance with the standard requirement, otherwise, the pipeline is adjusted until the transverse deviation is in accordance with the standard requirement. After the pipeline is laid in the ditch, the phenomenon that the bottom of the pipeline is suspended cannot occur. The pipeline cannot be emptied and the baffle falls. The pipe should be prevented from colliding with the trench wall to prevent collapse of the trench wall and damage to the pipe.

Pipeline butt joint

1. Cleaning a tube chamber and a tube opening: and cleaning all impurities in the socket and spigot, and then uniformly smearing a non-oily lubricant in the rabbet.

2. Cleaning a rubber ring: cleaning the adhesive on the rubber sealing rubber ring, and uniformly coating a non-oily lubricant.

3. Sleeving a rubber ring on the insertion opening: the sealing rubber ring should be smooth and have no distortion. When the rubber ring is installed, the rubber ring is rolled in place uniformly, after external force is released, the resilience is not larger than l0mm, the rubber ring is bent into a heart shape or a flower shape (large caliber) and is arranged in the rabbet groove, and the rubber ring is pressed once along the whole rubber ring by hand, so that all parts of the rubber ring are ensured not to warp and twist and are clamped in the groove uniformly and uniformly. The rubber ring is positioned on the tongue-and-groove working surface after being positioned.

Top-mounted interface

When the interface is installed in a top mode, a portal frame is adopted, a steel wire rope is tied on a firmly installed pipe during matching, a back beam is erected at the position of a pipe socket to be pulled in, the steel wire rope and a chain block are connected to be tightened and aligned, the chain block is pulled synchronously at two sides, and a socket sleeved with a rubber ring is pulled into a rabbet after being collided; the position and the condition of the rubber ring are corrected at any time; and checking whether the position of the rubber ring is correct or not in the gap of the secondary bell and spigot of the trial rod. As shown in FIG. 4, for a large-diameter pipeline, the pipeline is difficult to align by using a chain block, and at the moment, the pipeline can be aligned by using a loader and other machines to push the rear part of the pipeline. When mechanical opening alignment is adopted, the operation needs to be slow and soft, and a protective measure needs to be arranged at the rear part of the pipeline so as to prevent the pipeline from being damaged.

After each pipe joint is installed, the axis position and the elevation of the pipe body are corrected, and after the design requirements are met, axial locking and two-side fixing of the pipe body can be carried out.

6. HDPE winding reinforced B-shaped pipe installation

Tube laying: is carried out manually or by a crane. The pipe with the nominal diameter DN less than 500 is manually lowered, and during manual pipe lowering, ground personnel can transfer the pipe to groove bottom constructors. And for the large-excavated groove with the depth larger than 3m, the two ends of the pipe body can be tied by using non-metal ropes, the pipe is kept to be evenly and smoothly put into the groove, and the pipe is strictly prevented from rolling into the groove from the edge of the groove. The pipe with the nominal diameter DN being more than or equal to 500 is put down by the crane, and when the pipe is put down by the crane, the pipe is buckled by a nonmetal rope system, and the core-crossing hoisting is strictly forbidden.

Adjusting the length of the pipe: cutting with an electric saw, wherein the end face is vertically flat and should not be damaged.

Pipe connection

HDPE pipes are connected by socket electrothermal welding, a pipeline with the diameter less than DN400mm is formed by firstly using a hemp rope to hang a socket of a pipe B by one person, obliquely inserting a long prying bar into a foundation by the other person, abutting against a transverse baffle plate at the central position of the end part of the pipeline, and then forcibly and slowly inserting the pipe B into a bell mouth of the pipe A to a preset position; the pipeline with the diameter of more than DN400mm can be pulled to be in place by 2 hand-plate hoists with the weight of 0.50 ton, and when the interface is closed, the hand-plate hoists on the two sides of the pipeline section are pulled synchronously. In order to prevent the axial line position of the pipeline arranged firstly from moving when the connector is closed, a pipe stabilizing measure is required, yellow sand can be filled into the woven bag, the woven bag is sealed, the top of the pipeline arranged firstly is pressed, the specific quantity is different according to the pipe diameter, and after the connector of the pipeline, the height and the axial line of the pipeline are checked again to meet the requirements.

The pipeline is connected with the inspection well by adopting short pipes, the pipe socket is arranged in the water inlet direction of the inspection well, and the pipe socket is arranged in the water outlet direction of the inspection well.

Pipe welding

The pipeline welding adopts a special welding machine for the B-shaped pipe and other auxiliary welding tools. For pipelines of DN900 and above, the welding current is preheated for about 2min before welding, so that the welding quality is improved.

The welding process flow comprises the following steps:

checking and cleaning a pipe socket → socket butting → setting parameters → welding → heating the pipe and observing the melting degree → pipe welding, clasping → cooling to the specified time → taking out the tool.

In the welding process, the welding process should be properly adjusted according to changes of weather, environmental temperature, actual conditions and the like when necessary.

TABLE 2B type winding pipe welding process table

Description of the drawings: 1) The welding tool is a special welding machine for the B-shaped pipe.

2) According to the difference of welding machine, weather, environment temperature, etc., the welding process can be properly regulated, and the deviation is not more than 10%.

7. Interface processing

1) Pipe joint processing

In the sand blowing and filling area where the engineering is located, if the drainage pipeline leaks, sand and soil loss can be caused, the foundation soil is loose, even a cavity is formed, and great hidden danger is caused to the upper structure. Therefore, it is important that the drainpipe prevents leakage. For the interface treatment of the concrete pipeline, besides the rubber sealing ring, two protective measures of steel wire mesh cement mortar smearing belt and geotextile wrapping are additionally added.

Asbestos cement is used for filling joints between the interior and the exterior of the reinforced concrete pipe joint. The outer wall was taped with 1.

In order to prevent sand from losing with water under the condition of slight leakage of pipeline, before backfilling pipeline, it uses more than or equal to 250g/m ² The non-woven geotextile wraps the pipeline interface and the connector of the pipeline and the inspection well. The circumferential overlapping length is 500mm.

The HDPE pipelines are connected by adopting electric hot melting, and the interfaces do not need special treatment except for wrapping the geotextile.

2) Connection process of pipeline and well

The joint of the pipeline and the well is filled with oil-immersed hemp thread, the inner opening is filled with 1:2 cement mortar, the outer opening is filled with asbestos cement, and the corner is plastered by 1:2 cement mortar. And then wrapped with a layer of geotextile as shown in figure 6.

8. Testing of pipe systems

And performing a tightness test after the gravity flow drainage pipeline is installed. The tightness test can adopt a water-closing test or a gas-closing test, and the project is supposed to adopt the mode of the water-closing test.

The sewage pipeline can be put into operation after being qualified through a tightness test. When the inner diameter of the rainwater pipeline is larger than 700mm, 1/3 of the inner diameter of the rainwater pipeline can be sampled and selected according to the number of well sections of the pipeline for testing; when the test is unqualified, the number of the sampling well sections is doubled on the basis of the original sampling to carry out the test.

The water-stop test should be carried out after the pipeline is filled with water for 24 hours.

The water level of the water closing test is 2m below the inner top of the upstream pipeline of the test section, and if the height from the inner top of the upstream pipeline to the inspection port is less than 2m, the water level of the water closing test can reach the wellhead.

The determination time of the water seepage amount is not less than 30min.

TABLE 3 allowable water seepage amount in non-pressure pipeline water-closing test

When the inner diameter of the pipeline is larger than the specification of the upper table, the actually measured water seepage amount is smaller than or equal to the allowable water seepage amount calculated according to the following formula;

q＝1.25√Di

the measured water permeability of the HDPE pipe should be less than or equal to the allowable water permeability calculated according to the following formula.

q＝0.0046Di

Wherein q represents the allowable water seepage amount (m 3/24 h.km); di-inner diameter (mm) of the pipe.

9. Trench backfill

Cleaning up sundries such as bricks, stones, wood blocks and the like in the groove; the filling of miscellaneous filling soil, humus soil and construction waste can not be carried out. The backfill soil does not contain stones, bricks and other hard objects; no water is accumulated in the groove; backfilling around the well chamber is carried out simultaneously with backfilling of the pipeline groove; when the operation is inconvenient, step-shaped connecting stubbles are required to be left; backfilling around the well chamber is carried out symmetrically along the center of the well chamber in real time, and no ramming leakage is required; the backfill material is tightly attached to the well wall after being compacted;

the compaction operation of the reinforced concrete pipeline groove backfill meets the following regulations:

1. backfilling and compacting are carried out layer by layer without damaging the pipeline, and the layered thickness of each layer of backfilled soil is controlled to be 200mm;

2. in the real-time segmented backfill, the connecting stubbles of adjacent segments are in a step shape, and no ramming leakage is needed;

3. when light compaction equipment is adopted, the tamping is needed to be connected;

4. trench backfill should be symmetrical from both sides simultaneously.

The groove backfill operation of the HDPE reinforced winding B-shaped pipe meets the following regulations:

1. before backfilling, the pipeline is checked to have no damage or deformation, and the damaged pipeline is required to be repaired or replaced;

2. the inner diameter of the flexible pipeline is larger than 800mm, and a vertical support is arranged in the flexible pipeline during backfilling construction;

3. measures for preventing the pipeline from floating upwards and displacing are adopted when the pipeline is backfilled below the radius;

4. and backfilling the pipeline from two sides of the pipeline simultaneously and tamping the pipeline simultaneously.

Backfill process

In order to avoid damaging the pipeline, according to design and specification requirements, artificial backfilling is needed within a range from the bottom of the pipe to 0.5m above the top of the pipe, the reinforced concrete pipeline is within a range from the bottom of the pipe to 0.8m above the top of the pipe, the HDPE reinforced winding B-shaped pipeline is within a range from the bottom of the pipe to 1m above the top of the pipe, heavy machinery is not needed to be adopted for tamping, and the engineering is supposed to adopt small-sized compaction equipment such as frog rammers, plate rammers, small-sized impact rammers and the like for tamping.

The backfilled soil is undisturbed soil, but the soil cannot contain humus, construction waste, stones, bricks and other hard objects.

The soil quality of the project is sandy soil, and the auxiliary compaction can be carried out by adopting a watertight method according to the characteristics of the sandy soil. The watertight method is to inject water into the sand backfilled by layers to make the sand vibrate or compact the surface layer under the condition of saturated water. The water sealing method has certain compactness and stability.

The specific operation is as follows: firstly, filling sandy soil with a certain thickness, leveling, and then uniformly injecting water into the backfill soil layer, wherein the water injection rate is based on that no clear water exists on the surface layer, so that the backfill soil reaches the saturated water content. After standing for a period of time, tamping the backfill soil with a small compaction device, as shown in fig. 7; in the backfilling and compacting process, normal operation of the precipitation equipment is always kept to form sufficient osmotic pressure so that the injected water can smoothly permeate.

The trench backfill is accepted according to JTS257-2008 "quality inspection Standard for Water transportation engineering".

TABLE 4 base slot backfill allowable deviation, number of tests and method

10. Submersible sewage pump installation

The submersible sewage pump is fixedly installed, the water pump is matched with the automatic coupling device, the control cabinet and the water level controller, and the submersible sewage pump is automatically started and stopped according to the water level.

A submersible sewage pump installation step:

1) Installing a guide rod and a pump seat: the pump base is lifted and slowly lowered to the foundation, the bolt holes in the pump base are right opposite to the foundation embedded foundation bolts, the foundation bolts are screwed after the pump base is leveled by the horizontal ruler, the bottom of the guide rod is firmly connected with the pump base, and the top of the guide rod is connected with the support frame.

2) And (3) mounting a pump body: the pump body is lifted, the coupling device (the coupling device, the water pump and the motor are generally made into an integral device) is placed in the guide rod, the pump body is slowly descended along the guide rod until the coupling device is connected with the water outlet bent pipe on the pump base, and the central line of the water outlet pipe of the water pump is coincided with the central line of the inlet of the water outlet bent pipe, as shown in fig. 8.

11. Rainwater pump house equipment installation

The pump house installation process flow is shown in fig. 9.

12. Construction works

The drainage structure of the engineering comprises a rainwater inspection well, a sewage inspection well, a ditch pipe connecting well, a pressure sewage inspection well and the like. Are all of reinforced concrete structure.

Excavation of foundation pit

Before excavation construction, measuring the detailed position, gradient and excavation depth of the inspection well by a measurer; soil about 20cm is reserved at the bottom of the pit during mechanical excavation, the soil is manually cleaned according to the designed bottom standard, the foundation soil is prevented from being disturbed, and meanwhile, a water accumulation pit is arranged to keep a working surface free of accumulated water.

Because the ground water level is higher, the construction needs to set up light well point precipitation according to actual conditions, and the excavation depth sets up one deck well point precipitation within 3m, and 3 ~ 5m sets up two-layer well point precipitation.

The slope of foundation ditch excavation is decided according to engineering actual conditions, adopts 1 within 3 m: 0.75,3-5m adopts 1:1, and can adopt temporary support measures such as steel pipes and wood plates (bamboo fence). The excavation section is shown in fig. 10.

And then processing reinforcing steel bars according to the provisions of Water transport engineering quality inspection Standard (JTS 257-2008), binding the reinforcing steel bars, supporting templates, pouring concrete and vibrating for 20-30 seconds generally, wherein the vibrating time is based on the condition that the concrete surface is horizontal, cement paste appears and bubbles do not appear any more, and the concrete does not sink obviously any more.

When the compressive strength reaches 2.5MPa, the template can be disassembled to ensure that the surface and edges are not damaged due to the template disassembly.

After the template is removed, backfilling the two sides according to the structure layer of the yard, and tamping the layers; the compactness meets the design requirement.

Maintenance of concrete

After the concrete is poured, the concrete is covered by geotextile in time, and after hardening, moisture is preserved and maintained. Watering for curing under the condition of natural temperature (above 5 ℃), wherein the curing time is generally not less than 7 days and nights; the watering frequency is 3-4 times per day within the first three days after concrete pouring under the general air temperature condition (about 15 ℃), at least 2 times per day during the later curing period, the surface of the concrete is kept in a wet state, and the watering frequency is properly increased under the dry weather condition. When the temperature is not lower than +5 ℃ under the natural temperature condition, watering and maintaining are not required.

Well backfill

And after the strength of the cast-in-place concrete reaches the strength specified by the design, backfilling is started, and the backfilled soil is preferably soil dug in the foundation trench but does not contain organic impurities. The grain diameter is not more than 50mm, and the water content is in accordance with the specification. Backfilling around the well chamber should be performed simultaneously with backfilling the pipeline groove, and when backfilling around the well chamber and backfilling of the pipeline groove are inconvenient to perform simultaneously, step-shaped connecting stubbles should be left; and the backfill around the well chamber is symmetrically carried out along the center of the well chamber in real time, and no missing ramming is required.

When the construction of a road structure layer is carried out, besides the rolling by a road roller, a frog rammer or a vertical impact rammer is adopted to perform additional ramming within 60 cm around a well layer by layer so as to remove rolling dead angles.

The technical means disclosed in the invention scheme are not limited to the technical means disclosed in the above embodiments, but also include the technical scheme formed by any combination of the above technical features.

Claims

1. A construction process of a foundation pit drainage system in a coastal region is characterized by comprising the following steps: the method comprises the following steps:

(1) Selecting a pipeline: the diameter of the buried drain pipe is less than 1500mm, and a B-shaped pipe is wound and reinforced by adopting HDPE; the pipe diameter is more than or equal to 1500mm, and a reinforced concrete rabbet pipe is adopted; the buried pressure sewage pipe adopts a steel wire mesh skeleton polyethylene composite pipe; various drainage structures are all of reinforced concrete structures;

(3) Excavating a foundation trench: the depth of the groove is determined jointly according to the elevation of the bottom of the pipeline designed by a construction drawing and the actually measured elevation of the original soil ground; the excavation depth is 2-4.8 m; longitudinally arranging drainage ditches at two sides in the base groove, wherein the width of each drainage ditch is 20cm, the depth of each drainage ditch is 20-30cm, water collecting wells with the size of 1m × 1m are arranged at intervals of 20-30m, the longitudinal gradient of each drainage ditch is the same as that of each groove, the water collecting wells are lower than the bottoms of the drainage ditches by 50cm, all the submersible pumps are submerged in water, and the water is pumped to adjacent rainwater wells through the water pumps;

(4) Installing a pressure sewage pipeline;

(5) Installing a reinforced concrete rabbet pipe;

the pipeline foundation comprises a gravel cushion layer, a concrete cushion layer and a concrete foundation;

the pipeline hoisting adopts a sectional type pipe lowering, namely, reinforced concrete rabbet pipes are respectively hoisted one by one and then are put into the groove for assembly; adopting a rubber sealing ring for connection; finally, when the connector is installed in a jacking mode, a portal frame is adopted, a steel wire rope is tied on the stably installed pipeline during matching, a back beam is erected at the position of a pipeline socket to be pulled in, the steel wire rope and the chain blocks are connected to be tightened and aligned, the chain blocks are synchronously pulled on two sides, and the socket with the rubber ring sleeved is pulled into the rabbet after being hit;

(6) HDPE winding reinforced B-shaped pipe installation

Laying pipes in the groove, connecting the pipes by socket electrothermal welding, and preheating the pipes with DN900 or above for 2min before welding; the pipeline is connected with the inspection well by short pipes, the pipe socket is arranged in the water inlet direction of the inspection well, and the pipe socket is arranged in the water outlet direction of the inspection well;

(7) Interface leak-proof treatment:

asbestos cement is used for filling joints between the interior and the exterior of the reinforced concrete pipe joint; the outer wall is plastered with 1;

before backfilling the pipeline, using the slurry to fill the pipeline with more than or equal to 250g/m ² Wrapping the pipeline connector by the non-woven geotextile; the lap length in the circumferential direction is 500mm;

the HDPE winding reinforced B-shaped pipe is connected by electric hot melting and is used for being more than or equal to 250g/m ² Wrapping the pipeline connector by the non-woven geotextile;

(8) Performing a tightness test after the pipeline is installed;

(9) Backfilling the groove after the test is qualified

(10) The submersible sewage pump is fixedly installed, the water pump is matched with an automatic coupling device, a control cabinet and a water level controller, and the submersible sewage pump is automatically started and stopped according to the water level;

(11) Installing rainwater pump room equipment;

the slope of foundation ditch excavation is decided according to engineering actual conditions, adopts 1 within 3 m: 0.75,3-5m using a 1:1, temporary support measures of steel pipes, wood plates and bamboo fences can be adopted;

and then binding steel bars, supporting templates, pouring concrete, vibrating, removing the templates, maintaining, and beginning backfilling and tamping after the strength of the concrete structure reaches the designed strength.

2. The process for constructing the foundation pit drainage system in the coastal region according to claim 1, wherein the process comprises the following steps: step (3) the adoption within 3m of foundation trench depth is once only put the slope and is excavated, and the slope is 1.0, and the slot degree of depth is greater than 3m and sets up hierarchical excessive platform, and the platform width is excavator operation width, and hierarchical excavation slope is 1.0.

3. The process for constructing the foundation pit drainage system in the coastal region according to claim 1, wherein the process comprises the following steps: corresponding drainage and drainage measures are required in the foundation trench excavation process in the step (3), the concrete is guaranteed not to be soaked in water before the concrete reaches the design strength, the excavation surface is expanded during construction, and meanwhile, the excavation length is shortened, and every 30m is one section; and for the part with small excavation depth and low underground water level, arranging a drainage open trench and a water collecting pit in the trench, if underground water seeps out, enabling the underground water to flow to the drainage open trench and then to be collected to the water collecting pit, and then pumping away by using a centrifugal water pump.

4. The process for constructing the foundation pit drainage system in the coastal region according to claim 1, wherein the process comprises the following steps: adopting C20 concrete for the pipeline concrete foundation, pouring for 2 times, pouring for the first time to the pipe bottom elevation, and then installing a pipeline; and after the pipeline is installed, pouring the rest part.

5. The process for constructing the foundation pit drainage system in the coastal region according to claim 1, wherein the process comprises the following steps: in the step (5), all impurities in the bell and spigot are firstly removed and cleaned, and then non-oily lubricant is uniformly smeared in the tongue and groove; uniformly coating a non-oily lubricant on the surface of the rubber sealing ring; bending the rubber sealing ring into a heart shape or a flower shape, loading the rubber sealing ring into the groove, and pressing the rubber sealing ring once along the whole rubber sealing ring by hand to ensure that all parts of the rubber sealing ring are not warped and twisted and are uniformly and uniformly clamped in the groove; the rubber ring is positioned on the tongue-and-groove working surface after being positioned.

6. The construction process of the coastal region foundation pit drainage system according to claim 1, wherein: the HDPE winding reinforced B-shaped pipes in the step (6) are connected by socket electrothermal welding, a pipeline with the diameter less than DN400mm is hung on a socket of the B-shaped pipe by one person, the other person uses a long prying bar to insert the base in an inclined mode and abut against a transverse baffle plate in the center of the end part of the pipeline, and then the B-shaped pipe is inserted into a socket of the A-shaped pipe to a preset position; the pipeline with the diameter of more than DN400mm is pulled to be in place by 2 hand-plate hoists with the weight of 0.50 ton, and when the interface is closed, the hand-plate hoists on the two sides of the pipeline are pulled synchronously; in order to prevent the axial line position of the pipeline arranged firstly from moving when the connector is closed, a pipe stabilizing measure is required, and the specific method can fill yellow sand in the woven bag, seal the woven bag and press the top of the pipeline arranged firstly.

7. The process for constructing the foundation pit drainage system in the coastal region according to claim 1, wherein the process comprises the following steps: the compaction process for backfilling the reinforced concrete pipeline groove in the step (9) comprises the following steps:

3. tamping by adopting a frog rammer or a plate rammer light compaction device;

4. the groove backfilling is carried out symmetrically from two sides at the same time;

1. the inner diameter of the flexible pipeline is larger than 800mm, and a vertical support is arranged in the flexible pipeline during backfilling construction;

2. when backfilling is carried out below the radius of the pipeline, measures for preventing the pipeline from floating upwards and displacing are taken;

8. The construction process of the coastal region foundation pit drainage system according to claim 1, wherein: in the tamping process in the step (9), if the soil is sandy soil, a watertight method is adopted for auxiliary compaction: firstly, backfilling 200mm sandy soil, leveling, and then uniformly injecting water into a backfill soil layer, wherein the water injection amount is based on no open water on the surface layer, so that the backfill soil reaches the saturated water content; and after standing for 5-20min, tamping the backfill soil by small compaction equipment of a frog rammer or a plate rammer.

9. The process for constructing the foundation pit drainage system in the coastal region according to claim 1, wherein the process comprises the following steps: step (10) the submersible sewage pump installation step:

1. installing a guide rod and a pump seat: lifting the pump base, descending to the foundation, enabling the bolt holes in the pump base to be over against foundation bolts embedded in the foundation, leveling the pump base by using a horizontal ruler, and then screwing down the foundation bolts; the bottom of the guide rod is connected with the pump base, and the top of the guide rod is connected with the support frame;

2. and (3) mounting a pump body: and hoisting the pump body, placing the coupling device into the guide rod, and enabling the pump body to descend along the guide rod until the coupling device is connected with the water outlet bent pipe on the pump seat.