CN101041961A - Vacuum infiltration adsorption reinforcing method for soft soil foundation - Google Patents
Vacuum infiltration adsorption reinforcing method for soft soil foundation Download PDFInfo
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- CN101041961A CN101041961A CN 200710021492 CN200710021492A CN101041961A CN 101041961 A CN101041961 A CN 101041961A CN 200710021492 CN200710021492 CN 200710021492 CN 200710021492 A CN200710021492 A CN 200710021492A CN 101041961 A CN101041961 A CN 101041961A
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- draining
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- soft foundation
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Abstract
The invention discloses a vacuum penetrate adsorption strengthen method on soft foundation, belonging to construction technique, which arranges vertical discharge and exhaust tubes in the foundation, and lays communicated network horizontal discharge and exhaust tubes on the surface of the foundation, and connects the two kinds of tubes, arranges injection vacuum device at the ends of the horizontal tubes, lays geotechnical fabric and 2-3 layers of geotechnical films at the upper part of the horizontal tubes, while the circumference of geotechnical film is pressed 50cmm into waterproof foundation, and uses injection vacuum device to vacuum the discharge and exhaust systems of solid network, to discharge the free water and gas in soil, when the ground sink speed is 2mm/d in continuous five days, stops the injection vacuum device, to complete the strengthening on the soft foundation. The invention has deeper vacuum transmission, short construction period, saved sand resource and reduced cost on unit area than traditional vacuum pre-press method.
Description
One, technical field
The invention belongs to the engineering construction field, be specifically related to vacuum infiltration adsorption reinforcing method a kind of at soft foundation, especially coastal, riverine sludge soil base.
Two, background technology
Soft foundation is a lot of to the accident of bringing on the engineering, defective, reduce the harm of soft foundation, and engineers and technicians must be familiar with the characteristic of local weak soil.So-called weak soil is at hydrostatic or deposits in the flowing water environment slowly, through the saturated weak cohesive soil of biological chemistry action formation.China Construction Industry Press publish " the engineering geology handbook claim weak soil be " weak soil be meant that natural moisture content is big, compressibilty is high, supporting capacity is low a kind of softly mould the cohesive soil that stream is moulded state, as mud, mucky soil and the saturated cohesive soil of other high-compressibilities etc. ".Characteristic index has also been done following statement: when natural void ratio e greater than 1.5 the time, be called mud; Natural void ratio greater than 1.0 o'clock, is called mucky soil less than 1.5.
At present, the method for soft soil foundation is divided into dynamic consolidation method, displacement method, consolidation and compound foundation method four classes on the engineering, and wherein a kind of vacuum method in the consolidation is most widely used.
Traditional vacuum preloading technology is:
1, lays the 40cm sand cushion;
2, set plastic draining board, set up vertically to draining, exhaust passage;
3, the plastic draining board end is embedded in the sand cushion, arranges the PVC plastics person in charge and arm among sand cushion, constitutes horizontal drainage, exhaust system;
4, the jetting stream vacuum device is responsible for the PVC plastics and is linked to each other;
5, lay 2～3 layers of geotechnological film thereon, be pressed into below the relative impervious stratum 50cm around the geotechnological film;
6, by the jetting stream vacuum device, extract the vacuum that the PVC plastics are responsible for, make that the vacuum under the film reaches more than 80～90kPa;
7, in jetting stream vacuum device extracting vacuum process, according to the condition difference of former foundation soil, the time of extraction is more than 90 days, and is the longest for 1 year; The condition that stops to vacuumize was as the criterion less than 2mm/d with surface settlement speed in continuous 5 days;
8, surface settlement is more than or equal to the desired calculating sedimentation of national technical specification index;
9,, air-permeable layer permeable for underground part carried out the sealing of clay wall or cement soil wall;
10, reach the Soft Ground purpose.
The shortcoming of this method is:
1) vacuum must be by sand cushion, and transmits to the deep by band drain, and its efficient is low, and energy loss is big;
2) must lay sand cushion, the natural resource of waste sand because the sand cushion material is more expensive, has improved construction cost simultaneously;
3) be responsible for and arm adopts the PVC plastic pipe further to increase cost, and lead, branch diameter differs has increased the construction burden;
4) the construction processing time long, delay construction speed.
5), single reinforcing area is subjected to the restriction of construction technology, can't adapt to large area region and (reinforce area greater than 2.8 ten thousand m
2) needs.
Three, summary of the invention
The objective of the invention is in order to improve the vacuum pre-press reinforcing effect, shorten the construction period, to reduce the engineering construction cost and a kind of vacuum infiltration adsorption reinforcing method of soft foundation is provided, and can realize secondary development this method.
The vacuum infiltration adsorption reinforcing method of a kind of soft foundation of the present invention, it comprises following step:
1), at first in soft foundation, be provided with many in length and breadth vertically to draining, exhaust passage, each vertically to the level interval of draining, exhaust passage between 0.8～1.5m;
2), lay on soft foundation surface many be interconnected and the level of network-like structure to draining, exhaust passage, it has certain resistance to compression and tensile strength, and has good non-deformability, and at the saturating simultaneously soil particle of draining, exhaust.Horizontal spacing 0.8～1.8m, longitudinal pitch 3～15m.
3), will vertically directly be connected to draining, exhaust passage with level to the unearthed position of draining, exhaust passage, thereby constitute cubic network draining, exhaust system in the soft foundation aspect;
4), to draining, end, exhaust passage the jetting stream vacuum device is set in level, described jetting stream vacuum device is by 600～1000m
2The vacuum pressure that the balanced configuration of/l platform cover, jetting stream vacuum device and level are connected to draining, exhaust passage is greater than 96kPa;
5), lay the geotextile that prevents to destroy geotechnological film to draining, top, exhaust passage in level;
6), on geotextile, lay 2～3 layers of geotechnological film, be pressed into the following sealing area that forms of fluid-tight relatively stratum 50cm around the geotechnological film;
7), extract the cubic network draining by the jetting stream vacuum device, the vacuum of exhaust system, make level to draining, vacuum in the exhaust passage reaches more than 80～90kPa, and directly along vertically to draining, the exhaust passage is efficient transmits toward the deep, in the soil body and the vertical hydraulic gradient that between drainage channel, forms, impel the interior Free water of the soil body to permeate to drainage channel to vertical with gas, these water are gentle to capillary, under siphon and the pressure reduction acting in conjunction, along vertically to draining, the exhaust passage is drawn onto level to draining, the exhaust passage is extracted out outside the stabilization zone by the vacuum jet system again;
8), local surface sedimentation rate stopped the work of jetting stream vacuum device less than 2mm/d in continuous 5 days, finished the reinforcing to soft foundation.
In the step 1) can be the plastic draining board that sets, permeable corrugated flexible hose, sand drain or sand wick etc. to draining, exhaust passage vertically, what adopted is the seepy material that can form drainage channel in the soil body, this material also has certain flexibility, intensity and permeable, airing function, requires to have certain capillary or siphonage.
Step 2) level in is to have certain resistance to compression and tensile strength to draining, exhaust passage, and has good non-deformability, and draining, exhaust simultaneously not saturating soil particle function be plastic film capicitor or permeable corrugated flexible hose, each manages horizontal spacing 0.8～1.8m, longitudinal pitch 3～15m.
Vertically adopt colligation connection, joint to connect or the embeddability connection in the step 3) to being connected to draining, exhaust passage with level.
Geotextile in the step 5) is colour bar cloth or spins geotextiles.
Geotechnological film in the step 6) is materials such as polyethylene film or polychloroethylene film, and this material must have certain tensile strength and elongation per unit length.
Extract in the vacuum process of cubic network draining, exhaust system in step 7), when local permeable, the air-permeable layer of underground appearances, employing clay wall or cement soil wall seal.
The relative prior art of the present invention has following advantage:
1, owing to adopted the draining of cubic network shape, exhaust passage system, and under geotechnological film covers formed sealing area, the vacuum transmission that the jetting stream vacuum device is extracted is lost little deeply and on the way, has improved its operating efficiency;
2, omit sand cushion, saved the natural resource of a large amount of sand, reduced construction cost;
3, owing to draining, exhaust efficiency significantly promote, obviously shortened the construction period;
4, network draining, exhaust system connect free, can carry out the engineering construction of site assembly formula, avoid the single area finiteness restriction of traditional vacuum precompressed;
5, can the many burdens of the selection of material classification have been reduced with the perforated plastic bellows of single caliber;
6, the unit area construction cost is starkly lower than the cost of traditional vacuum preloading.
Four, description of drawings
Fig. 1 is that cubic network of the present invention is vertically to draining, evacuation network structural representation;
Fig. 2 is that cubic network level of the present invention is to draining, evacuation network structural representation;
Fig. 3 is the foundation load trial curve figure before and after embodiment reinforces.
Five, the specific embodiment
Shown in Figure 2 as Fig. 1, present embodiment adopts step as follows:
1), in soft foundation, is provided with many in length and breadth vertically to draining, exhaust passage 1; Vertically adopt plastic draining board to draining, exhaust passage 1, sectional dimension is (100*4mm), outsourcing non-woven geotextile, specification 〉=90g/cm
2Spacing of prefabricated drain is 1.0m; Blossom type is arranged;
2), lay on soft foundation surface many be interconnected and the level of network-like structure to draining, exhaust passage 2; Level is laid and is of a size of 1.6*15m to the plastic film capicitor with holes of draining, exhaust passage 2 employing φ 60
2
3), will vertically directly be connected to draining, exhaust passage 2 with level to the unearthed position of draining, exhaust passage 1, every plastic draining board needs to twine more than two circles with horizontal bellows, and with rope made of hemp colligation in one;
5), lay one deck colour bar cloth as topping to draining, 2 tops, exhaust passage in level;
6), on topping, lay two layers of geotechnological film and form geomembrane and geotextile topping 4;
4), the film device of going into of vacuum jet system 3 is set, horizontal drainage, exhaust passage 2 outlets are installed with vacuum jet system and device 3, vacuum jet system 3 configuration quantity are by reinforcing area 600～1000m
2/ l platform cover calculates;
7), vacuum jet system 3 operation, ground begins sedimentation;
8), vacuum jet system 3 runs to settlement of foundation and the rate of settling always and satisfies till design, the code requirement;
9), finish reinforcing to soft foundation.
Certain development zone, strand industrial premises (case history)
This project is positioned at the coastal tidal area, is 25000m
2Industrialized standard factory building ground, geological mapping report shows, this ground mud matter silty clay that distributing, thickness of soft soil reaches more than the 12m in the 20m depth bounds, weak soil layer bearing capacity of foundation soil be in 45～60kPa scope, specifically ground index parameter table 1.
1, geological conditions
This project ground parameter index table table 1
| Title | Thickness | Moisture content w | Static sounding p s | Compression coefficient α | Mark passes through and hits several N 63.5 | Characteristic value f k |
| m | ％ | MPa | MPa -1 | Hit number | kPa | |
| Mud matter silty clay | 2.38 | 36.6 | 0.3 | 0.52 | 1.3 | 45～50 |
| Silt | 1.91 | 31.8 | 0.98 | 0.19 | 2 | 85～90 |
| Mud matter silty clay | 9.72 | 45.2 | 0.33 | 1.01 | 1.6 | 60 |
| Silt | 18.4 | 34.2 | 2.02 | 0.27 | 8 | 110 |
| Mud matter silty clay | ＞10 | 47.6 | 0.66 | 0.95 | 95 |
2, adopt the vacuum infiltration absorption method to handle
Because this project duration is tight, it is tighter that investment cost is controlled again, so adopt the vacuum infiltration absorption method to carry out treatment of soft foundation.Compare with the traditional vacuum precompressed, following variation takes place in construction technology: (1), cancellation sand cushion; (2), geomembrane adopts double-deckly, compares for three layers with the routine shop, reduced one deck; (3), increase geotextile overcoat under the skim; (4), the time that vacuumizes is actual has used 40 days.
Plastic draining board degree of depth 12m, spacing 1.0m mixes plastic draining board and the direct bundle of Water penetrative flexible pipe together, is built into cubic network draining, exhaust system.
3, validity check
Reinforce preceding two groups of loading tests: wherein table 2 is loading test data before reinforcing, and table 3 is to reinforce the back loading test;
Loading test table 2 before reinforcing
| Load | P(kPa) | 0 | 25 | 38 | 50 | 63 | 75 |
| Before the reinforcing | Accumulative | 0 | 10.98 | 20.25 | 30.94 | 48.52 | 70.1 |
| Accumulative | 0 | 15.62 | 28.27 | 41.22 | 66.12 | 118 |
Reinforce the two groups of loading tests in back:
Reinforce back loading test table 3
| Load | P(kPa) | 0 | 60 | 90 | 120 | 150 | 180 | 210 | 240 |
| After the reinforcing | Accumulative | 0 | 4.83 | 10.25 | 16.86 | 23.71 | 31.18 | 39.47 | 49.28 |
| Accumulative | 0 | 5.75 | 10.37 | 17.78 | 24.45 | 34.12 | 43.21 | 53.65 |
Above-mentioned data plotting is gone out loading test curve map (Fig. 3):
The loading test data shows that bearing capacity has improved nearly about 3 times, and effect is very obvious.Duration reduces significantly, and the processing method cost reduces significantly, and economy is very obvious.
The accumulative total maximum settlement reached 580mm in 40 days, and effect is obvious.Examining report shows that bearing capacity of foundation soil reaches 110kPa.
4 conclusions
(1), by the practical application of vacuum infiltration absorption method, find that there are some differences in its reinforcement effect and conventional vacuum preloading, as vacuum vertically in drainage channel the precompressed of attenuation ratio traditional vacuum many slowly.
(2), the construction period shortens significantly, compares with the traditional vacuum preloading, the construction period obviously shortens.
(3), vacuum infiltration absorption method reinforcing soft ground, its cost reduces by 10～15 yuan/m than the traditional vacuum preloading
2
Claims (7)
1, a kind of vacuum infiltration adsorption reinforcing method of soft foundation is characterized in that may further comprise the steps:
1), at first in soft foundation, is provided with many in length and breadth vertically to draining, exhaust passage;
2), lay on soft foundation surface many be interconnected and the level of network-like structure to draining, exhaust passage;
3), will vertically directly be connected to draining, exhaust passage with level to the unearthed position of draining, exhaust passage, thereby constitute cubic network draining, exhaust system in the soft foundation aspect;
4), to draining, end, exhaust passage the jetting stream vacuum device is set in level, described jetting stream vacuum device is by 600～1000m
2The vacuum pressure that/1 balanced configuration of cover, jetting stream vacuum device and level are connected to draining, exhaust passage is greater than 96kPa;
5), lay the geotextile that prevents to destroy geotechnological film to draining, top, exhaust passage in level;
6), on geotextile, lay 2～3 layers of geotechnological film, be pressed into the following sealing area that forms of fluid-tight relatively stratum 50cm around the geotechnological film;
7), extract the cubic network draining by the jetting stream vacuum device, the vacuum of exhaust system, make level to draining, vacuum in the exhaust passage reaches more than 80～90kPa, and directly along vertically to draining, the exhaust passage is efficient transmits toward the deep, in the soil body and the vertical hydraulic gradient that between drainage channel, forms, impel the interior Free water of the soil body to permeate to drainage channel to vertical with gas, these water are gentle to be inhaled at hair, under siphon and the pressure reduction acting in conjunction, along vertically to draining, the exhaust passage is drawn onto level to draining, the exhaust passage is extracted out outside the stabilization zone by the vacuum jet system again;
8), local surface sedimentation rate stopped the work of jetting stream vacuum device less than 2mm/d in continuous 5 days, finished the reinforcing to soft foundation.
2, the vacuum infiltration adsorption reinforcing method of soft foundation according to claim 1, it is characterized in that vertical in the step 1) is the plastic draining board that sets, permeable corrugated flexible hose, sand drain or sand wick to draining, exhaust passage, each vertically to the level interval of draining, exhaust passage between 0.8～1.5m.
3, the vacuum infiltration adsorption reinforcing method of soft foundation according to claim 1 and 2 is characterized in that step 2) in level be plastic film capicitor or permeable corrugated flexible hose to draining, exhaust passage, each manages horizontal spacing 0.8～1.8m, longitudinal pitch 3～15m.
4, the vacuum infiltration adsorption reinforcing method of soft foundation according to claim 1 and 2 is characterized in that vertically adopting colligation connection, joint to connect or the embeddability connection to being connected to draining, exhaust passage with level in the step 3).
5, the vacuum infiltration adsorption reinforcing method of soft foundation according to claim 1 and 2 is characterized in that the geotextile in the step 5) is colour bar cloth or spins geotextiles.
6, the vacuum infiltration adsorption reinforcing method of soft foundation according to claim 1 and 2 is characterized in that the geotechnological film in the step 6) is polyethylene film or polychloroethylene film.
7, the vacuum infiltration adsorption reinforcing method of soft foundation according to claim 1 and 2, it is characterized in that extracting in the vacuum process of cubic network draining, exhaust system in step 7), when local permeable, the air-permeable layer of underground appearance, adopt clay wall or cement soil wall to seal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN 200710021492 CN101041961A (en) | 2007-04-16 | 2007-04-16 | Vacuum infiltration adsorption reinforcing method for soft soil foundation |
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|---|---|---|---|
| CN 200710021492 CN101041961A (en) | 2007-04-16 | 2007-04-16 | Vacuum infiltration adsorption reinforcing method for soft soil foundation |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009070984A1 (en) * | 2007-11-02 | 2009-06-11 | Yonggen Liang | Vacuum preloading method without drain sand cushion layer |
| WO2010028547A1 (en) * | 2008-09-11 | 2010-03-18 | 中国科学院武汉岩土力学研究所 | Stereoscopic network drainage device for accelerating water drainage consolidation velocity of hydraulic mud fill |
| CN102828499A (en) * | 2012-05-04 | 2012-12-19 | 上海港湾基础建设（集团）有限公司 | Improved quick high vacuum densification soft foundation treatment method |
| CN104865371A (en) * | 2015-05-22 | 2015-08-26 | 长沙学院 | Experiment device and method for consolidation of soft foundation under vacuum condition |
-
2007
- 2007-04-16 CN CN 200710021492 patent/CN101041961A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009070984A1 (en) * | 2007-11-02 | 2009-06-11 | Yonggen Liang | Vacuum preloading method without drain sand cushion layer |
| WO2010028547A1 (en) * | 2008-09-11 | 2010-03-18 | 中国科学院武汉岩土力学研究所 | Stereoscopic network drainage device for accelerating water drainage consolidation velocity of hydraulic mud fill |
| CN101357817B (en) * | 2008-09-11 | 2010-06-09 | 中国科学院武汉岩土力学研究所 | Stereoscopic network drainage for accelerating water drainage consolidation velocity of hydraulic mud fill sludge |
| CN102828499A (en) * | 2012-05-04 | 2012-12-19 | 上海港湾基础建设（集团）有限公司 | Improved quick high vacuum densification soft foundation treatment method |
| CN104865371A (en) * | 2015-05-22 | 2015-08-26 | 长沙学院 | Experiment device and method for consolidation of soft foundation under vacuum condition |
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