Utilize threaded stirring shaft to reduce the job practices of foundation deformation on every side
Technical field
What the present invention relates to is a kind of job practices of construction engineering technical field, specifically is that a kind of threaded stirring shaft that utilizes reduces the job practices of foundation deformation on every side.
Background technology
The bury deep mixing method is to utilize cement (or lime) as curing compound, adopt a kind of special deep mixer tool, in the ground deep cement (or lime) and bury are forced to mix, the column, wall shape or the bulk that bury are hardened become to have certain intensity add solid.These add solid and have globality, water stability and enough intensity preferably, form composite foundation with natural ground, bear upper load jointly.The deep layer stirring technique formally is applied to engineering practice from nineteen seventies, has been widely used at present in the construction of industry and civilian construction, subway, highway, municipal administration, water conservancy, harbor approach and Offshore Units etc.
Stir in the construction in deep layer, adopt deep mixer that cement paste is mixed with bury.Shaft is arranged on the mixer, and its head has stirring vane.In mixer when rotation, by shaft end shotcrete pipe ejection cement paste, mix with being rotated the soil body that blade stirs pine, forms the cement stabilization body.Stir in the construction in deep layer, the injection that distinct issues are cement pastes can cause the expansion of the soil body, produces bigger lateral deformation around in the ground.Can cause bigger influence to the adjacent structure basis like this, especially, be easy to cause serious environmental problem in the intensive area of City Building.
Through existing technical literature retrieval is found, Chai JC, Miura N, Koga H is at " Journal ofGeotechnical and Geoenvironmental Engineering ", ASCE, 131 (5): 623-632, " the Lateral Displacement of Ground Caused by Soil-cementColumn Installation " that May 2005 delivers (" cement-soil mixes the lateral deformation of stirring the stratum that causes in the construction " that " geotechnical engineering and rock environment journal " 2005.5 that American Society of Civil Engineers sponsors delivered), this article is mentioned the deep layer stirring can cause soil expansion, produce bigger lateral deformation around in the ground, and provided the method that stirs prediction soil lateral in the construction in deep layer, but this article does not solve the problem of the lateral deformation that how to reduce the soil body.
Summary of the invention
The present invention is directed to the deficiencies in the prior art and defective, provide a kind of threaded stirring shaft that utilizes to reduce the job practices of foundation deformation on every side, to the influence of surrounding environment, job practices is simple and reliable, and is economical and practical when making it can effectively reduce deep layer stirring construction.
The present invention is achieved by the following technical solutions, may further comprise the steps:
(1) leveling place.
(2) fixedly stirring-head is also located.Stirring-head is fixed on the shaft that has spiral thread, and crane suspention mixer is to specifying stake position and centering.
(3) stir.When shaft sinks, make the rotation direction of shaft consistent with the spiral thread direction, upper and lower two-layer stirring vane is rotated down cutting soil under the drive of shaft, and a part of simultaneously soil body that is stirred pine is taken out of by the rotation of screw thread on the shaft.By the casting amount that the subsidence velocity and the velocity of rotation of shaft are controlled screw thread, the casting amount is advisable to be no more than the cement slurry volume that will inject.
(4) stirring sinking stops to sink until the following 5cm of projected depth.
(5) at above-mentioned absolute altitude place, upper and lower shotcrete pipe is whitewashed simultaneously, and whitewashing is stirred simultaneously, continues 5 minutes.
(6) upwards promote shaft and spray cement paste, require the rotation direction of shaft opposite this moment with the spiral thread direction, and the cement paste that prevents to spray into is with moving on the spiral thread.Shaft hoisting depth upper and lower shotcrete pipe in 30cm is whitewashed simultaneously, and the shaft hoisting depth is closed down shotcrete pipe after surpassing 30cm, and last shotcrete pipe continues whitewashing.
(7) stirring is promoted to design elevation, stops to stir promoting, and the soil body that the cleaning shaft is taken out of is finished the construction of an agitation pile.
The outer diameter D of spiral thread is 2 times of inner diameter d, and the upper and lower spacing of spiral thread is provided with top stirring vane and bottom stirring vane on the shaft about 100mm, and two blade pitghs are 300mm, and top stirring vane and bottom stirring vane are 90 ° of settings.
The present invention has changed and has used the method for smooth cylindrical metal tube as shaft in the past, at the spiral thread about processing spacing 100mm on the smooth cylindrical metal tube.Utilize agitation pile that the present invention constructs in the rotation process of shaft, earlier the on-the-spot soil body is discharged a part by spiral helicine screw thread, cement paste reinjects.In the mixing pile construction process, just can not cause foundation deformation on every side like this, reduce influence surrounding environment.And because the discharge of the soil body, shotcrete pipe surrounding soil reaction force attenuation can reduce the stifled slurry that takes place and emit the slurry phenomenon in the deep layer whipping process, can improve quality and efficient that deep layer stirs greatly.
The present invention is easy to process, does not need extra equipment, and job practices is simple and reliable, and is economical and practical.Be applied to deep layer and stir the reinforcing bury, can not cause foundation deformation on every side, reduced influence, reduced stifled slurry simultaneously and emitted the slurry phenomenon, improved quality and efficient that deep layer stirs greatly surrounding environment.Through the engineering practice checking, obtained significant effect.
Description of drawings
Fig. 1 is a construction flow chart of the present invention.
The specific embodiment
The present invention adopts a kind of deep-mixed pile shaft that utilizes to reduce the job practices of foundation deformation on every side.In conjunction with the invention provides following examples:
Embodiment:
The test site is the mixing pile construction in certain express highway roadbed engineering.With 4 of the agitation piles of the deep mixer construction of band helical form shaft.With 4 of the deep-mixed piles of traditional worker's method construction.The long 13.6m that is of stake, stake footpath 1000mm, water/binder ratio 1:0.5.The outer diameter D of spiral thread is 20cm on the shaft that adopts, and inner diameter d is 10cm.The upper and lower spacing of spiral thread is 100mm, and top stirring vane and bottom stirring vane are set on the shaft, and two blade pitghs are 300mm, and top stirring vane and bottom stirring vane are 90 ° of settings.
As shown in Figure 1,1-7 among the work progress of every test pile such as the figure, specific as follows:
1. leveling place.
2. fixedly stirring-head is also located.Stirring-head is fixed on the shaft that has spiral thread, and crane suspention mixer is to specifying stake position and centering.
3. stir.When shaft sinks, make the rotation direction of shaft consistent with the spiral thread direction, upper and lower two-layer stirring vane is rotated down cutting soil under the drive of shaft, and a part of simultaneously soil body that is stirred pine is taken out of by the rotation of screw thread on the shaft.Control shaft velocity of rotation at 40rpm, the about 0.5m/min of subsidence velocity.
4. stir and stop to sink until-13.65m.
5. at-13.65m absolute altitude place, upper and lower shotcrete pipe is whitewashed simultaneously, and whitewashing is stirred simultaneously, continues 5 minutes.
6. upwards promote shaft and spray cement paste, this moment, the rotation direction of shaft was opposite with the spiral thread direction, and the cement paste that prevents to spray into is with moving on the spiral thread.The velocity of rotation of shaft is still kept 30-60rpm, the about 1m/min of hoisting velocity, shaft stirring-head absolute altitude-upper and lower shotcrete pipe was whitewashed simultaneously when 13.35m was following, the stirring-head absolute altitude-close down shotcrete pipe when 13.35m is above, last shotcrete pipe continues to whitewash.
7. stir and be promoted to the face of land, stop to stir lifting, the soil body that the cleaning shaft is taken out of is finished the construction of an agitation pile.
Site test results shows in band spiral thread shaft work progress, almost do not have lateral deformation on every side in the ground, and stifled slurry do not occur and emit the slurry phenomenon, and the pile quality that obtains is good.And adopt the deep-mixed pile of traditional worker's method construction to cause the about 25cm of maximum lateral displacement on stratum on every side, and stifled slurry phenomenon appears when constructing the 3rd pile.The lateral deformation on stratum on every side of adopting the inventive method construction to cause only is about 1/10th of conventional method.
Embodiment shows that the deep-mixed pile shaft that adopts spiral thread can prevent effectively that deep layer from stirring the lateral deformation that produces in the construction, and can reduce the stifled slurry that produces in the construction greatly and emit the slurry phenomenon, effectively improves mixing quality and efficient.