CN102561372A

CN102561372A - Plugging method for downcomer for well-point dewatering of deep foundation pit

Info

Publication number: CN102561372A
Application number: CN2011104361838A
Authority: CN
Inventors: 刘宝堂
Original assignee: China MCC17 Group Co Ltd
Current assignee: China MCC17 Group Co Ltd
Priority date: 2011-12-23
Filing date: 2011-12-23
Publication date: 2012-07-11
Anticipated expiration: 2031-12-23
Also published as: CN102561372B

Abstract

The invention provides a plugging method for a downcomer for the well-point dewatering of a deep foundation pit, and belongs to a falling water plugging method of civil engineering. The plugging method comprises the construction steps as follows: firstly, a filtering layer is disposed; secondly, a sand layer is filled; thirdly, a cotton batting layer is stuffed; fourthly, a soluble glass cement sand bed is poured; fifthly, a leaking stoppage agent layer is smeared; sixthly, a micro-expansive concrete layer is poured; and seventhly, a plugging steel plate is welded, wherein the filtering layer arranged at the lower part of an inner chamber of a conventional downcomer remains the same, and the sand layer is filled until the height of the sand layer reaches 1.5 meters below the top of the downcomer; the height of the cotton batting layer ranges from 0.7 to 1.0 m; the thickness of the soluble glass cement sand bed ranges from 50 to 80 mm, and the soluble glass cement sand bed is curdled when poured; the thickness of the leaking stoppage agent layer ranges from 40 to 60 mm; the micro-expansive concrete layer is poured until the height reaches the upper pipe orifice of the downcomer; and the round steel plate is utilized to plug an upper opening of the downcomer above the micro-expansive concrete layer in a full-length welding manner, wherein the thickness of the round steel plate ranges from 8 to 15 mm. The plugging method effectively solves the difficult problem that leakage is caused when the downcomer is plugged, is simple and convenient to operate, and has the advantages of quick construction progress, high construction quality and low cost.

Description

The downcomer method for blocking of Deep Foundation Pit Well-Point Dewatering

Technical field

The invention belongs to worker China Democratic National Construction Association precipitation method for blocking, especially relate to a kind of method for blocking of Deep Foundation Pit Well-Point Dewatering.

Background technology

When high-building construction, because groundwater table is higher, excavation of foundation pit is darker, generally all need adopt the construction of well-points dewatering method to carry out precipitation; So that the construction on excavation of foundation pit and basis, but when foundation construction finishes and removes well-points dewatering equipment, because the underground water hydraulic action can cause downcomer shutoff difficulty; Generally speaking, in downcomer, fill rubble, build high-grade concrete then below concrete roof 50mm, adopt the thick steel plate of 10mm again the downcomer sealing; But because of ground water pressure is bigger, stop precipitation after, underground water gushes on still can be in a large number; Downcomer shutoff position easy to leak not only causes difficulty of construction big, and construction quality is difficult to control; And construction back hidden danger is many, concrete of basement base plate infiltration in the future, and leak stopping is difficulty very.

Summary of the invention

The downcomer method for blocking that the purpose of this invention is to provide a kind of Deep Foundation Pit Well-Point Dewatering solves the difficult problem that the downcomer shutoff produces seepage effectively, and not only easy and simple to handle, construction speed is fast, and improves construction quality, reduces construction cost.

The objective of the invention is to realize like this: a kind of downcomer method for blocking of Deep Foundation Pit Well-Point Dewatering, its construction sequence is:

One, the disposal of filtration beds, two, fill layer of sand, three, the plug cotton layer, four, pouring water glass cement sand bed, five, smear and apply leak stopping king layer, six, build the slightly expanded concrete layer, seven, the stifled steel plate of sealing;

Wherein:

One, the disposal of filtration beds:

After in downcomer, the draining water pump lifting being come out; The filtration beds that is provided with in former downcomer inner chamber bottom maintains the original state constant; Promptly buried for to prevent that the set strainer of task performance of impurity effect water pump in the precipitation well from maintaining the original state constant in the bottom of downcomer; This strainer adopts the finished product filter screen, and void content is not less than 20%.

Two, fill layer of sand:

Above downcomer inner filtration layer, fill layer of sand; Fine sand in the employing, fine sand granularity is that 0.25mm to 0.35mm is advisable in this, fine sand is through 20 orders and the screening of 40 purpose sieves in this; Must not contain impurity, the height of this layer of sand is filled to downward 1.5m depths, downcomer top; Layer of sand answers puddling real, and compactness is 90% get final product, and layer of sand is filled and wanted layering filling, layering puddling reality, and is good with thick middle fine sand and the tamping of each filling 50cm.

Three, plug cotton layer:

After filling layer of sand; Immediately the cotton-wool volume of wrapping is filled in the top of layer of sand in the downcomer; The diameter of this cotton-wool volume is than the big 15-30mm of downcomer internal diameter, and the diameter of this cotton-wool volume is good than the big 20mm of downcomer internal diameter, and the height of this cotton layer is 0.7-1.0m; The height of this cotton layer is good with 0.8m especially, to play water proof, to prevent the purpose of gushing on the underground water;

Four, pouring water glass cement sand bed:

In the downcomer behind the jam-pack cotton layer; The water glass cement sand bed is watered on top at cotton layer immediately, and this water glass cement mortar bed thickness is 50mm-80mm, and this water glass cement mortar bed thickness is good with 60mm; With irritating with coagulating; 1), water glass sand cement water glass cement main material:: commercially available, modulus n=2.2,40 ° of Be of density, 2): No. 32.5 Portland cements, 3): river sand, fineness modulus u _f=2.4; The proportioning of this water glass cement mortar is: cement: sand: water: water glass=565Kg:1380Kg:360Kg:113L promptly: 1kg:2.44kg:1.57kg:200ml; Water glass elder generation and water mix; Be poured into again to mix in cement and the sand and process mortar; Make local cement mortar produce rapid hardening when avoiding water glass directly to pour into, prevent to stir inhomogeneous.

Five, smear deposited leak stopping king layer:

On the water glass cement sand bed that condenses, smear to apply and stop up king's layer, this stops up king's bed thickness is 40mm-60mm, and this stops up king's bed thickness is good with 50mm;

Six, build the slightly expanded concrete layer:

After obstruction king layer solidifies; Build the slightly expanded concrete layer on obstruction king layer top; The proportioning of this slightly expanded concrete is: (cement+expansion agent): sand: rubble: water: water reducing agent=(348Kg+36Kg): 744Kg:1071Kg:178Kg:3.5Kg; That is: (1Kg+0.10Kg): 2.14Kg:3.08Kg:0.51Kg:0.01Kg, concrete is No. 32.5 Portland cements; The vibration compacting while building, by conventional maintenance, this slightly expanded concrete layer is poured into till the mouth of pipe of downcomer upper end always, and after building, concrete expands and the downcomer strong bonded, prevents that concrete is loosening, guarantees the shutoff quality;

Seven, the stifled steel plate of sealing:

Treat that micro-expansion cement reaches after the design strength 75%, with the thick round plate of 8-15mm downcomer full weld suitable for reading is blocked on the top of micro-expansion cement layer.

The downcomer method for blocking of a kind of Deep Foundation Pit Well-Point Dewatering provided by the present invention, easy to operate, solved the difficult problem that the downcomer shutoff produces seepage effectively, not only construction speed is fast, and improves construction quality, reduces construction cost.

Combine accompanying drawing and embodiment that the downcomer method for blocking of a kind of Deep Foundation Pit Well-Point Dewatering of the present invention's proposition is described further at present.

Description of drawings

Fig. 1 is that the downcomer method for blocking of Deep Foundation Pit Well-Point Dewatering proposed by the invention is implemented sketch map.

Among Fig. 1: 1, filtration beds 2, back-up sand layer 3, cotton layer 4, water glass cement sand bed 5, leak stopping king layer 6, micro-expansion cement layer 7, round plate.

The specific embodiment

Embodiment

B form a team project 8# building downcomer in lotus flower village adopts the downcomer method for blocking of this Deep Foundation Pit Well-Point Dewatering in Nanjing; Its construction sequence is: the filtration beds of burying underground when keeping the draining dewatering construction 1; Fill layer of sand 2; Middle fine sand is filled to downward 1.5m depths, downcomer top, uses thick tight cotton layer 3 shutoff as 0.8m then, then uses thick water glass cement paste layer 4 as 50mm (promptly envelope is promptly coagulated) and thick leak stopping king layer 5 as 50mm successively; Leak stopping king layer 5 top adopt C35 slightly expanded concrete layer 6 to be poured into the downcomer upper end mouth of pipe; At last on micro-expansion cement layer 6, use the thick round plate of 10mm 7 again with downcomer full weld sealing, the top concreting of round plate 7 and use thick build as 40mm pea gravel concreten and concrete floor concordant, through the careful conscientious inspection repeatedly of correlation engineering technician; Do not find downcomer seepage phenomenon, effect is obvious; In follow-up 12#, 13# building downcomer shut-in well, continue to construct with this method; The step of going forward side by side has been demonstrate,proved the effect of its antiseep; Solved the technical barrier of downcomer shutoff moisture-proof and seepage-proof effectively, and under the prerequisite that guarantees workmanship, made constructing operation easy; Accelerate construction speed, reduced cost.

Claims

1. the downcomer method for blocking of a Deep Foundation Pit Well-Point Dewatering, its construction sequence is:

Wherein:

One, the disposal of filtration beds:

After in downcomer, the draining water pump lifting being come out; The filtration beds that is provided with in former downcomer inner chamber bottom maintains the original state constant; Promptly buried for to prevent that the set strainer of task performance of impurity effect water pump in the precipitation well from maintaining the original state constant in the bottom of downcomer; This strainer adopts the finished product filter screen, and void content is not less than 20%;

Two, fill layer of sand:

Above downcomer inner filtration layer, fill layer of sand, fine sand in the employing, fine sand granularity is 0.25mm to 0.35mm in this, and fine sand must not contain impurity through 20 orders and the screening of 40 purpose sieves in this, and the height of this layer of sand is filled to downward 1.5m depths, downcomer top; Layer of sand answers puddling real, and compactness is 90%, and layer of sand is filled and wanted layering filling, layering puddling in fact;

Three, plug cotton layer:

After filling layer of sand, immediately the cotton-wool volume of wrapping is filled in the top of layer of sand in the downcomer, the diameter of this cotton-wool volume is than the big 15-30mm of downcomer internal diameter, and the height of this cotton layer is 0.7-1.0m, to play water proof, to prevent the purpose of gushing on the underground water;

Four, pouring water glass cement sand bed:

In the downcomer behind the jam-pack cotton layer; The water glass cement sand bed is watered on top at cotton layer immediately; 1), water glass this water glass cement mortar bed thickness is 50mm-80mm, with irritating with coagulating water glass cement main material:: commercially available, modulus n=2.2,40 ° of Be of density; 2) sand, cement: No. 32.5 Portland cements, 3): river sand, fineness modulus u _f=2.4; The proportioning of this water glass cement mortar is: cement: sand: water: water glass=565Kg:1380Kg:360Kg:113L promptly: 1kg:2.44kg:1.57kg:200ml; Water glass elder generation and water mix; Be poured into again to mix in cement and the sand and process mortar; Make local cement mortar produce rapid hardening when avoiding water glass directly to pour into, prevent to stir inhomogeneous;

Five, smear deposited leak stopping king layer:

On the water glass cement sand bed that condenses, smear to apply and stop up king's layer, this stops up king's bed thickness is 40mm-60mm;

Six, build the slightly expanded concrete layer:

Seven, the stifled steel plate of sealing:

Treat that slightly expanded concrete reaches after the design strength 75%, with the thick round plate of 8-15mm downcomer full weld suitable for reading is blocked on the top of micro-expansion cement layer.

2. the downcomer method for blocking of Deep Foundation Pit Well-Point Dewatering according to claim 1, the diameter that it is characterized in that this cotton layer are than the big 20mm of downcomer internal diameter, highly be 0.8m.

3. the downcomer method for blocking of Deep Foundation Pit Well-Point Dewatering according to claim 1 is characterized in that this water glass cement mortar bed thickness is 60mm.

4. the downcomer method for blocking of Deep Foundation Pit Well-Point Dewatering according to claim 1 is characterized in that this this obstruction king bed thickness is 50mm.

5. the downcomer method for blocking of Deep Foundation Pit Well-Point Dewatering according to claim 1 is characterized in that and layer of sand is filled to thick middle fine sand and the tamping of each filling 50cm.