CN102561372B

CN102561372B - Plugging method for downcomer for well-point dewatering of deep foundation pit

Info

Publication number: CN102561372B
Application number: CN201110436183.8A
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: 2014-04-09
Anticipated expiration: 2031-12-23
Also published as: CN102561372A

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 work 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 to 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 remove well-points dewatering equipment, due to the effect of underground water hydraulic pressure, can cause downcomer shutoff difficulty, generally, in downcomer, fill rubble, then build high-grade concrete until below concrete roof 50mm, adopt again steel plate that 10mm is thick by downcomer sealing, but because of ground water pressure larger, stop after precipitation, underground water gushes on still can be in a large number, downcomer shutoff position easy to leak, not only cause difficulty of construction large, construction quality is difficult to control, and after construction, hidden danger is many, concrete of basement base plate infiltration in the future, leak stopping is difficulty very.

Summary of the invention

The downcomer method for blocking that the object of this invention is to provide a kind of Deep Foundation Pit Well-Point Dewatering, solves the difficult problem that 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 object of the present invention is achieved 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, plug cotton layer, four, pouring water glass cement sand bed, five, smear and apply leak stopping king layer, six, build slightly expanded concrete layer, seven, the stifled steel plate of sealing;

Wherein:

One, the disposal of filtration beds:

After draining water pump being enhanced in downcomer, the filtration beds arranging in former downcomer inner chamber bottom maintains the original state constant, at the buried set strainer of task performance for impurity effect water pump in preventing dewatering well in the bottom of downcomer, maintain the original state constant, this strainer adopts finished product filter screen, and void content is not less than 20%.

[0005]two, fill layer of sand:

Above downcomer inner filtration layer, fill layer of sand, fine sand in employing, in this, 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 object sieves, 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%, and layer of sand is filled and wanted layering filling, layering puddling reality, and take and fill middle fine sand that 50cm is thick tamping as good at every turn.

Three, plug cotton layer:

Fill after layer of sand, immediately the cotton-wool volume of wrapping is filled in to the top of layer of sand in downcomer, the diameter of this cotton-wool volume is than the large 15-30mm of downcomer internal diameter, and the diameter of this cotton-wool volume is good than the large 20mm of downcomer internal diameter, the height of this cotton layer is 0.7-1.0m, the height of this cotton layer be take 0.8m especially as good, playing water proof, prevent the object of gushing on underground water.

Four, pouring water glass cement sand bed:

In downcomer after jam-pack cotton layer, water glass cement sand bed is watered on top at cotton layer immediately, this water glass cement mortar bed thickness is 50mm-80mm, and this water glass cement mortar bed thickness be take 60mm as good, with filling with solidifying, 1), water glass water glass cement main material:: commercially available, modulus n=2.2,40 ° of Be of density, 2), cement: No. 32.5 Portland cements, 3), sand: river sand, fineness modulus uf=2.4; The proportioning of this water glass cement mortar is: cement: sand: water: water glass=565Kg:1380Kg:360Kg:113L: 1kg:2.44kg:1.57kg:200ml, water glass elder generation and water mix, be poured into again cement and become mortar with mixing in sand, while avoiding water glass directly to pour into, make partial water cement mortar produce rapid hardening, prevent from stirring inhomogeneous.

Five, smear and apply leak stopping king layer:

On the water glass cement sand bed condensing, smear and apply leak stopping king layer, the thickness of this leak stopping king layer is 40mm-60mm, and the thickness of this leak stopping king layer be take 50mm as good.

Six, build slightly expanded concrete layer:

After leak stopping king layer solidifies, on leak stopping king layer top, build slightly expanded concrete layer, 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, maintenance routinely, till this slightly expanded concrete layer is poured into the downcomer upper end mouth of pipe always, after building, concrete expansion and downcomer strong bonded, prevent that concrete is loosening, guarantees shutoff quality.

Seven, the stifled steel plate of sealing:

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

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

The downcomer method for blocking of a kind of Deep Foundation Pit Well-Point Dewatering now in conjunction with the accompanying drawings and embodiments the present invention being proposed is described further.

Accompanying drawing explanation

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

In 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

[0015]at lotus flower village, the Nanjing B project 8# building downcomer of forming a team, adopt the downcomer method for blocking of this Deep Foundation Pit Well-Point Dewatering, its construction sequence is: the filtration beds 1 of burying underground while retaining draining dewatering construction, fill layer of sand 2, middle fine sand is filled to downward 1.5m depths, downcomer top, then with thick be tight cotton layer 3 shutoff of 0.8m, then with thick, for the water glass cement paste layer 4(of 50mm seal, coagulate successively) and the thickness leak stopping king layer 5 that is 50mm, leak stopping king layer 5 top adopt C35 slightly expanded concrete layer 6 to be poured into the downcomer upper end mouth of pipe, last on micro-expansion cement layer 6, use again round plate 7 that 10mm is thick by downcomer full weld sealing, the top concreting of round plate 7 is also built concordant for 40mm pea gravel concreten with concrete floor with thick, through the careful conscientious inspection repeatedly of correlation engineering technician, do not find downcomer Seepage, successful, in follow-up 12#, 13# building downcomer shut-in well, continue to construct by this method, the step of going forward side by side has been demonstrate,proved the effect of its antiseep, effectively solved the technical barrier of downcomer shutoff moisture-proof and seepage-proof, and guaranteeing under the prerequisite of workmanship, make constructing operation easy, accelerate construction speed, reduced cost.

Claims

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

Wherein:

One, the disposal of filtration beds:

After draining water pump being enhanced in downcomer, the filtration beds arranging in former downcomer inner chamber bottom maintains the original state constant, at the buried set strainer of task performance for impurity effect water pump in preventing dewatering well in the bottom of downcomer, maintain the original state constant, this strainer adopts 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 employing, in this, fine sand granularity is 0.25mm to 0.35mm, and in this, fine sand, through 20 orders and the screening of 40 object sieves, must not contain impurity, 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:

Fill after layer of sand, immediately the cotton-wool volume of wrapping is filled in to the top of layer of sand in downcomer, the diameter of this cotton-wool volume is than the large 15-30mm of downcomer internal diameter, and the height of this cotton layer is 0.7-1.0m, playing water proof, prevent the object of gushing on underground water;

Four, pouring water glass cement sand bed:

In downcomer after jam-pack cotton layer, water glass cement sand bed is watered on top at cotton layer immediately, this water glass cement mortar bed thickness is 50mm-80mm, with filling with solidifying, 1), water glass water glass cement main material:: commercially available, modulus n=2.2,40 ° of Be of density, 2), cement: No. 32.5 Portland cements, 3), sand: 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: 1kg:2.44kg:1.57kg:200ml, water glass elder generation and water mix, be poured into again cement and become mortar with mixing in sand, while avoiding water glass directly to pour into, make partial water cement mortar produce rapid hardening, prevent from stirring inhomogeneous;

Five, smear and apply leak stopping king layer:

On the water glass cement sand bed condensing, smear and apply leak stopping king layer, the thickness of this leak stopping king layer is 40mm-60mm;

Six, build slightly expanded concrete layer:

After leak stopping king layer solidifies, on leak stopping king layer top, build slightly expanded concrete layer, 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, maintenance routinely, till this slightly expanded concrete layer is poured into the downcomer upper end mouth of pipe always, after building, concrete expansion and downcomer strong bonded, prevent that concrete is loosening, guarantees shutoff quality;

Seven, the stifled steel plate of sealing:

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

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 than the large 20mm of downcomer internal diameter, be highly 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 the thickness of this leak stopping king layer is 50mm.

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