Double-layer compound vacuum prepressing blowing filling soft soil foundation treatment method
The present invention relates to coastal blowing filling soft soil foundation treatment technology, more particularly to a kind of double-layer compound vacuum preloading weak soil
The method of basement process, belongs to Geotechnical Engineering field.
With the continuous expansion of Process of Urbanization Construction scale, being skyrocketed through of foreign trade, China coast port city
Enter an all-round developing new period, reclaim fields from the sea on a large scale, the engineering such as polder competitively develops, and becomes coastal opening
Put a beautiful landscape line in city.The ground engineering of making of coastal area all faces a major issue, and that is, such area mostly is height
Moisture content, the silt clay of high-compressibility, need a kind of efficiently, the technological means of energy-conservation and environmental protection to be processing, then from two
From the 80s and 90s in tenth century, technique of soft soil foundation treatment just arises at the historic moment as a kind of new technology processing soft soil foundation, and
Constantly develop and perfect in decades, just have various vacuum preloading treatment technology today；From single vacuum precompressed skill
Art, to vacuum combined stack-load, vacuum combined strong rammer, low position vacuum preloading, depth layer combine vacuum preloading and vacuum combined electricity
The effective engineering method of various synthesis such as ooze, the development course of technique of soft soil foundation treatment has witnessed China and reclaimed fields from the sea the great achievement of engineering
And promoted it rapidly to develop.
Find through engineering practice, although conventional vacuum prestressing technology is a kind of more effective at present blowing filling soft soil foundation
Treatment technology, but there is this larger limitation.For example, it is used coarse sand to provide drainage path and routine as sand bedding course
The simple cluster of longitudinal water-permeable pipe connects drain bar etc., all can cause at the geomembrane soil body toward deep soil internal vacuum
Loss is more serious, and inside soil body discharging consolidation effect is bad.And the saturated dredger soft soil ground for the process larger 15～20m of depth
Base, traditional treatment method is difficult to look after deep soil, causes the firmly interior soft less effective phenomenon of table, such as in low position vacuum preloading
The upper strata soil body be that discharging consolidation is completed by low level horizontal vacuum pipe, do not reach expected consolidation effect, extend simultaneously yet
Reinforcing cycle.It is also desirable to lay sand in " reclaimed ground double-face vacuum precompressed construction technology is studied with consolidation effect " literary composition
Bed course is used as the process of bottom soft soil foundation.Number of patent application is 200810153628 double-layer low-position vacuum preload consolidation dress
Put and soft soil foundation reinforcing method " in vacuum pipe network strictly do not adopt encapsulation process, it is low to there is vacuum energy utilization ratio,
Easily cause vacuum transmission to be obstructed.Patent publication No. is the side of the bidirectional vacuum prepressing blowing filling soft soil foundation of cn101235634a
In method, upper strata soft soil foundation is carried out in vacuum pre-pressed joint reinforcing as preloading to lower floor's Soft Soil Layer, the connection between vacuum tube is all
It is that fragility connects, joint easily causes brittle fracture, so that vacuum preloading interrupts.
Therefore the present invention proposes a kind of new double-layer compound vacuum pre-pressed soft soil foundation treatment technology, not only ensure that true under film
The transmission of reciprocal of duty cycle, has saved original bed course sand, and using manifold and hand-type joint to longitudinal drainage and vacuum tube
Carry out flexible sealing connection, reduce vacuum linear loss, upper strata weak soil is covered water as preloading combination deeper weak soil is carried out
Vacuum preloading is processed has the effect same processing with shallow-layer, accelerates the consolidation of the soil body, shortens the construction period, meets engineering real
The application on border needs.
Content of the invention
The present invention relates to a kind of double-layer compound vacuum prepressing ground foundation treatment method, the double-deck processing soft soil of the method utilization, gram
Take conventional single vacuum prestressing technology and processed depth not and the defect successively decreased with depth of under-membrance vacuum degree, increased true
Reciprocal of duty cycle is along the transmission efficiency of depth, and designs sealed drainage system and decrease the loss of under-membrance vacuum degree so that weak soil ground
Base processes depth and greatly increases, and upper half shallow layer soft soil carries out vacuum preloading processing mode, and lower half deep layer weak soil carries out vacuum simultaneously
With preloading joint preloading processing mode, compensate for deep layer due to the phenomenon of traditional approach draining difficulty consolidation effect difference.
To achieve these goals, double-layer compound processing means and sealed row are employed in the scheme that the present invention adopts
The technical solution of the present invention comprises the following steps:
(1) cofferdam and envelope wall are set around pretreatment place, with under-membrance vacuum degree during ensureing vacuum preloading not
Can be from the loss of soil body side；
(2) banket absolute altitude one half value by design, in the internal saturated dredger soft soil in cofferdam, lay two-layer separation layer on soil body top layer:
One layer of geotextiles of layer of geotextile；According to the lateral separation designed in insulation surface opening, set plastic draining board, will
30cm about long native table drain bar be connected with draining and vacuum tube using hand-type joint, finally in surface covering one to two-layer
(3) starting the vavuum pump initial stage of carrying out first vacuumizes, and discharges because of air in the film that stays during construction, in case upper earthing
Body, in deadweight lower compression geomembrane, stops vacuumizing when geomembrane is close to soil body top layer.
(4) continue in the internal saturated dredger soft soil in cofferdam to designed elevation, the arrangement and method for construction being previously mentioned in repeat step (2),
Define the setting of drain bar of the double-deck soil body, the connection of pipeline and the laying of separation layer afterwards.
(5) by completed for upper and lower both sides main draining and vacuum pipe pass-out, it is connected on vavuum pump, by the water extracted out in soil
Pour in cofferdam, the quantity of vavuum pump flexibly sets according to the area of disposal field, subsequently ensureing that covering geomembrane is lossless
In the case of start vavuum pump the soil body reach design the degree of consolidation after, that is, terminate construct.
The present invention is to propose on the basis of improved to traditional vacuum precompressed treatment technology, has a significant advantage that (1) increases
The big process depth of vacuum preloading, traditional processing method can only carry out shallow-layer process, the DeGrain of deep level of processing, meeting
The firmly interior soft phenomenon of table occurs.And the double-layer compound vacuum preloading processing method being related in the present invention, shallow soil is passed
System vacuumizes with reference to covering water process, and deep soil is then carried out cover water vacuum preloading preloading joint preloading simultaneously and carry out at ground
Reason, it is to avoid conventional method mid-deep strata soil body treatment effect not good enough consequence.(2) can avoid passing using sealed drainage system
In system technique, the use of bed course medium coarse sand, greatlys save resource, ensure that inside soil body vacuum transmission simultaneously.(3) this
The sealed drainage system of bright use is to be connected horizontal plastic draining board by hand-type joint with longitudinal drainage and vacuum tube, and
Mouth of pipe joint is wound around with plastic sheeting, to guarantee the sealing of pipeline.
Using double-layer compound vacuum preloading treatment technology for depth 15～20m saturated dredger soft soil process have with shallow-layer at
The same effect of reason.Present invention is mainly applied to the hydraulic reclamation of the large-scale key construction project such as coastal port city, railway, airport is soft
Native basement process, meets the actual requirement of engineering.
Fig. 1 double-layer compound of the present invention vacuum prepressing ground foundation treatment method profile.
Fig. 2 double-layer compound of the present invention vacuum prepressing ground foundation treatment method top view.
Fig. 3 sealed pipe used in the present invention 2 joint.
Fig. 4 sealed drain bar used in the present invention and pipe joint.
In conjunction with accompanying drawing 1, the construction procedure of the double-layer compound vacuum preloading process blowing filling soft soil foundation of the present invention is:
(1) before weak soil hydraulic reclamation starts, build cofferdam 1 first around pending place, and set envelope wall 2,
Guarantee in the work progress in later stage that air will not enter place it is ensured that under-membrance vacuum degree around the soil body.
(2) press the half of designed elevation value, carry out the work of weak soil 7 hydraulic reclamation inside cofferdam 1, be subsequently covered each by above
Last layer geotextile and geotextiles 3 as separation layer, to protect drainage system to separate with the soil body；Set by drain bar horizontal spacing
Evaluation, in the separation layer upper shed of laying, carry out plastic draining board 4 sets work.
(3) subsequently enter an important step of construction, 30cm about long native table plastic draining board and steel wire corrugation rows
Water and vacuum tube 5 are connected, and using hand-type tube sheet joint, joint carries out air-tightness guarantee using encapsulant, and prevents crisp
Property fracture.Then lay one to two-layer hdpe geomembrane 6 so that entirely constructing by actual conditions above the pipeline of laying
Journey carries out under air-proof condition it is ensured that construction quality.
(4) treat lower half layer sewerage system and after the completion of sealing system builds, starting vavuum pump 8 initial stage of carrying out vacuumizes, row
Except air in the film producing because of construction, in case the upper strata soil body is in Gravitative Loads lower compression geomembrane；After geomembrane is close to the soil body
Vavuum pump can be stopped.
(5) continue in the internal saturated dredger soft soil in cofferdam to designed elevation, the construction step being previously mentioned in repeat step (2)～(3)
Suddenly, the connection of double-layer compound weak soil drainage system and the work of sealing isolation layer laying are finally completed.
(6) by completed for upper and lower both sides main draining and vacuum pipe pass-out, it is connected on vavuum pump 8, subsequently ensureing to cover
Lid geomembrane is lossless and under-membrance vacuum degree generally should be controlled to reach 80～100kpa, just can start vavuum pump and be taken out
Vacuum, the water extracted out in soil is poured in cofferdam, and after the soil body reaches the design degree of consolidation, construction just completes.
Fig. 2 show the connected mode figure between the transverse drainage plate of the present invention and draining and vacuum tube, and both pass through to set
The hand-type joint of meter is attached the sealing it is ensured that drainage system.
Fig. 3, Fig. 4 show nipple and plastic draining board and pipeline between the draining of the present invention and vacuum pipe
Between hand-type joint, in addition jointing material guarantee air-tightness.
Protection scope of the present invention is not limited only to the description of the present embodiment.