CN1068083C

CN1068083C - Method for strengthening soft soil foundation by vacuum water-reducing combined with loading precompression

Info

Publication number: CN1068083C
Application number: CN 98105035
Authority: CN
Inventors: 苏锦文; 许镇鸿; 丘湘泉; 曾克耀; 魏汉坤
Original assignee: Shantou Niutianyang Economic Development Corp; Shantou Bureau Of Water Conservancy & Power
Current assignee: Shantou Niutianyang Economic Development Corp; Shantou Bureau Of Water Conservancy & Power
Priority date: 1998-01-23
Filing date: 1998-01-23
Publication date: 2001-07-04
Anticipated expiration: 2018-01-23
Also published as: CN1191256A

Abstract

The present invention relates to a prepressing method for consolidating soft soil foundations. The method is mainly characterized in that the inner parts of a pipe and a hose are pumped into vacuum, the inner part of a soil layer can generate negative pressure which is combined with pressure generated by stacking operation to prepress soft soil foundations, and larger prepressing load and better consolidating effect can be obtained; as a sealing film is not used for forming vacuum, the problem of disassembling the film does not exist; in addition, as the cost of the plastic draining hose is low, the plastic draining hose can be covered after the foundations are consolidated, which is favorable to accelerating the construction operation, and thereby, the present invention is an available ideal prepressing method for consolidating the soft soil foundations.

Description

A kind of method for strengthening soft soil foundation by vacuum water-reducing combined with loading precompression

The present invention is a kind of method with the preloading reinforcing soft ground.Be applicable to the road, stockyard of low-lying land and carry out fill in situations such as tidewater fluctuation areas and build lock.

What the preloading reinforcing soft ground had at home and abroad used on the engineering has three types, and these three types exist complex procedures, consolidation time is long, cost is high shortcoming separately to the found a capital reinforcing soft foundation under water of lock of the road of reinforcing low-lying land, stockyard etc. and tidewater fluctuation area fill.As the first kind is to load preloading, on soft base, set sand drain or draining band and spread sand cushion, on bedding plane, apply piling prepressing, it is self filler deadweight that dykes and dams are loaded, when the height that fills its requirement and when fixed, precompressed is finished, its shortcoming be weak soil drainage speed slowly and have lateral displacement to extrude, the rate of loading on controll day, consolidation time is quite long, and to the reinforcing soft foundation of building, after requiring the degree of consolidation when reaching, row building again after also need unloading, complex procedures, time is long, the cost height; Second class is the precipitating, pre-pressing method, setting dark about 6～8 meters lower end on soft base has the metal well casing of chimney filter and will manage to push up and be linked to be pipeline, borrow the suction of vacuum pump to make groundwater table decreasing, the effective weight that reduces the buoyancy increase soil layer in the soil reaches the precompressed purpose, shortcoming is will take out the high metal tube of cost to reach because the less chimney filter of oblique infiltration area, to reinforcing poor permeability and the darker muck foundation of fixed soil layer, consolidation time is longer, generally is applicable to the ground stabilization preferably of land permeability; The 3rd class is vacuum preloading or vacuum combined loading preloading, and this method is a kind of cost-effective reinforcing soft foundation method, but has following shortcoming for reinforcing soft base under water: the one, the ancillary works measure be arranged for the ditching press mold, and could form vacuum; The 2nd, tear film open because of the unloading of antiskid stability requirement, could continue construction, its complex procedures, the processing time increases relatively, and cost is also higher.

This reinforcing soft ground method provides a kind of vacuum extractor with centrifugal pump, in the seal section of pipe and band edge, form vacuum, make the method that produces the 80kpa negative pressure in the soil layer, this method can be converted into effective stress with interstitial hydraulic pressure in the soil layer, to replace a part of piling prepressing loading.

This reinforcing soft ground method also provides a kind of method, it makes the stabilization zone soil body be contraction to the center owing to the negative pressure of vacuum effect in vacuum, can carry out preloading immediately, and rate of loading can accelerate also, apply the soil body after the preloading and also do not produce and outwards extrude displacement.

This reinforcing soft ground method also has an advantage, need not form vacuum by diaphragm seal exactly, and the problem that it does not exist unloading to tear film open is convenient to enter immediately the construction working of next step.

Therefore, specific purposes of the present invention are to provide a kind of higher prefabricating load, operation is simple, the duration is short, cost is low reinforcement of soft soil method of obtaining.

Purpose of the present invention is realized by following scheme:

In fill on the weak soil aspect of tidewater fluctuation or on low-lying weak soil aspect, build the road and the ground stabilization of building such as stockyard, at first must back-up sand soil (land just not must this link), it is surfaced or to calculated height; Plug the plastic drain of band edge sealing in soft foundation, make the plastic drain lower end insert sludge blanket, its upper end seal section partly exposes bedding plane; Be communicated with the PVC hard plastic tube with the seal section of three-way connector plastic drain; On the PVC hard plastic tube, load onto vacuum pump and vacuumize; When vacuumizing stable reaching more than the 80kpa; to the PVC hard plastic tube covering protection that bankets; and press the design height one or many directly with the construction of mechanical back-up sand soil, and perhaps suspend and treat back-up sand soil after other areas are handled well equally, continue to be evacuated to the design fate and finish.

Fig. 1 is the generalized section of draining band of the present invention and pipeline;

Fig. 2 is that draining band of the present invention engages schematic diagram with three-way connector;

Fig. 3 is a three-way connector schematic diagram of the present invention;

Fig. 4 is the profile of Fig. 3 A-A;

The invention will be further described below in conjunction with accompanying drawing:

With reference to Fig. 1, the placing sand layer is about 0.4 meter on the mud face of test, for operations such as slotting band machines; End makes the upper part sealing with two-layer pvc film and the staggered sealing label of water-fast gummed paper on the plastic drain, and the length of this upper end seal section can be calculated according to geologic information and obtain, and this example is 2.8 meters; Plugging in length and breadth in soft foundation, spacing is 5 meters 500 * 3mm or the above-mentioned draining band 2 of 500 * 4mm, show according to geologic information, the sludge blanket of this soft foundation is in the about 9 meters depths of distance underground, above-mentioned for this reason draining band 2 its length are got 11.5 meters, make its lower end sludge blanket that can go directly, and seal section 3 parts in upper end are reserved bedding plane 0.7-1 rice; Draining band 2 seal sections are communicated with (referring to Fig. 2) with three-way connector 4, and band edge inserts behind the three-way connector with polychloroethylene film and water-fast gummed paper sealing label; With rubber hose a pair of PVC hard plastic tube 5 is communicated with (referring to Fig. 3) with three-way connector 4; Vacuum pump 6 is communicated with PVC hard plastic tube 5 by cross water inlet 8, loads onto weir 7 and sedimentation stake 9 at last, examination vacuumizes, and repairs gas leakage, when the vacuum pumping pump table is stabilized in more than the 80kpa, one meter high sand is protected and loaded to the pipeline earth backing.Shut down on January 23, in pumpdown time from 96 on October 9, to 97, and totally 106 days, remove middle shutdown maintenance 21 beyond the highest heavens, be 85 days in fact, pump table vacuum all remains between the 85-88kpa, illustrates that sealing performance is fine.Measure: maximum settlement is that 61 centimetres, minimum sedimentation are 40 centimetres (referring to table 1), has obtained better effects.

The present invention compared with prior art has the following advantages:

1, the precompressed loading of this reinforcing soft ground method is to replace a part of piling prepressing loading with the negative pressure that vacuumizes generation, can obtain higher prefabricating load or can reduce the height of preloading under the situation of identical precompressed loading;

2, in reinforcing process because the negative pressure of vacuum effect, make the stabilization zone soil body be contraction to the center, this not only makes rate of loading accelerate, and applies the soil body after the preloading and also be difficult for generation and outwards extrude displacement;

3, owing to forming vacuum by diaphragm seal, needn't be the same with vacuum combined loading precompressed, need ancillary works ditching voltage supply film, and the problem that does not exist unloading to tear film open;

4, this method is owing to adopt plastic drain, and its cost is low, it can be covered after the ground stabilization, needn't be the same with the precipitating, pre-pressing method, and need unloading to take out gutter;

5, this method is that also it can adopt 500 * 3mm or above big width plastic tape, its amount of infiltering is big, therefore, can be used for toppling over and making the setting of ground of built construction thing improve its bearing capacity of correction building, the linking that also can be used for the old and new's levee foundation of old dike heightening and thickening is handled and is reinforced.

The settlement observation record sheet Table 1

Claims

1. method for strengthening soft soil foundation by vacuum water-reducing combined with loading precompression; be used for low-lying land and contain the ground stabilization that to fill the permanent construction of several meters high sands by the designed use difference on the weak soil of absolute altitude below zero; elder generation's back-up sand layer goes out the water surface so that operation; on soft foundation, plug the plastic drain of band edge sealing; make the lower end of plastic drain seal section enter mud; the upper end seal section partly exposes sand cushion; and be communicated with the PVC hard plastic tube with the seal section of three-way connector with plastic drain; dress vacuum pump and vacuumizing on the PVC hard plastic tube; when vacuum pump is stabilized to more than the 80kPa; to the PVC hard plastic tube covering protection that bankets; and press the design height one or many directly with the construction of mechanical back-up sand soil, continue to be evacuated to the design fate and finish

2. according to the method for claim 1, it is characterized in that the plastic drain of above-mentioned band edge sealing is in same direction and by equidistantly plugging in length and breadth.

3. according to the method for claim 1 or 2, it is characterized in that the above-mentioned upper end seal section that exposes layer of sand is used polychloroethylene film and the staggered sealing of water-fast gummed paper after partly inserting three-way connector, is communicated with the PVC hard plastic tube.

4. according to the method for claim 3, it is characterized in that plastic drain adopts 500 * 3mm or above size.