CN1126264A

CN1126264A - Making method for non-annular borehole cast-in-place pile

Info

Publication number: CN1126264A
Application number: CN 94112980
Authority: CN
Inventors: 石寅生
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-12-26
Filing date: 1994-12-26
Publication date: 1996-07-10
Anticipated expiration: 2014-12-26
Also published as: CN1111230C

Abstract

The pile construction method features that special drilling machine is used to drill quincunx hole or other non-circular holes and concrete is poured to compolete pile. For the soil strata slumping not easily, reinforced cage is put down after drilling and concrete is then poured. For the soil strata slumping easily, cement slurry is poured via core hole of drill rod under action of high pressure after drilling to predetermined depth and then reinforced cage and aggregate are loaded down. Its advantages include high construction speed, saving raw materials and high load bearing power of pile.

Description

Making method for non-annular borehole cast-in-place pile

One, circular stake and quincunx comparison

All pump-grouting concretes all are columniform at present.For friction pile or based on friction one end bearing pile of frictional force, it is long to improve the bearing capacity of single pile stake that can only extend, and adds the timber pile footpath.Stake is long to be determined by the bearing stratum buried depth; When adding the timber pile footpath, the side surface area of stake increases with the first power in stake footpath, and meanwhile Zhuan volume but increases with the quadratic power in stake footpath.Obviously, adding the resulting frictional resistance in timber pile footpath and compare with the material usage of input, is very non-remunerative.If we can get out the quincuncial hole of non-circular such as many lobes, and can keep this hole not collapse finishing up to system stake, we just can save lot of materials when increasing bearing capacity of single pile, our employing of this quincunx (or other is non-circular) castinplace pile is its sign with S.P..

Our examination will be commonly used the circle stake quincunx S.P. close with it of diameter 800mm with side surface area compare:

The stake type	Long side surface area (the m of every 1m ²)	Long volume (the m of every 1m stake ³)	The side surface area ratio	Volume ratio
The stake type	Long side surface area (the m of every 1m ²)	Long volume (the m of every 1m stake ³)	The side surface area ratio	Volume ratio	Ф
800 circle stakes	???2.513	????0.563	???0.89	??2.40	Ф
800 circle stakes	???2.513	????0.563	???0.89	??2.40	Quincunx S.P. Ф 400 and 3 * Ф, 300 combinations	???2.827	????0.236	???1.00	??1.00

As can be known: identical stake is long, and Ф 800 a circle side surface area only are 89% of S.P., and volume (being the concrete consumption) but is 2.4 times of S.P..Moreover, S.P. adopts the high-pressure slip-casting infiltration, and side-friction force is all much bigger with the end load.Typical S.P. stake section configuration such as Fig. 1.Two, S.P. drill configuration principle

S.P. rig can be installed on the pile frame that any sufficiently high (long by stake) has slideway.Lean on hoist engine keyhole feed speed during boring and carry the drilling speed degree.Referring to Fig. 2.Among Fig. 2: 1. drill bit, 2. descend casing, 3. drilling rod, 4. in casing, 5. reductor and gear-box, 6. motor, 7. high-pressure hose, 8. cable, 9. 10. high pressure slurry pump of power supply (generator or switchbox), 11. pulpers, 12. portable drilling cramps.

Simplified structure such as Fig. 3.Among Fig. 3: 1. motor, 2. reducer, 3. air deflector (referring to Fig. 4), 4. gear-box, 5. central gear, 6. side gear, 7. limit drilling rod (dextrorotation), 8. center drilling rod (left-handed), 9. in casing (referring to Fig. 6), 10. end casing, 11. limit drill bits, 12. center bits

1. motor drives center drilling rod gear by planetary reduction gear (or hydraulic motor), drive 3 peripheral drilling rod gears, the number of teeth of all gears, modulus are all identical, therefore the identical and switched in opposite of the rotating speed of center drilling rod (screw thread is left-handed) and peripheral drilling rod (screw thread dextrorotation), the pitch of all drilling rods all is identical.

Each drill pipe diameter can have various combination selective: as Ф 400-n Ф 300, and Ф 500-n Ф 375, Ф 600-n Ф 450 etc., n=2 wherein, 3,4.(during n=2, drilling rod is grown up and is arranged the shape arrangement, but center drilling rod and outer drilling rod equal diameter) when selecting Ф 400-3 Ф 300 combinations for use, gas-distributing motor power 110KW, 980 rev/mins of rotating speeds, 28 rev/mins of rod rotation speeds are selected the high pile frame of 35m for use, can bore the dark boring of 30m.

2. dress air deflector (see figure 4) on each peripheral drilling rod connects the slip casting high-pressure hose, feeds to hole base pressure slurry.Periphery adorns that steel ball compresses the plasma discharge mouth automatically when boring under the detachable ball valve (see figure 5) under the drill bit, carries that steel ball falls to opening automatically when boring slip casting, when needing high-pressure rotary-spray, pulls down ball valve and changes special nozzle (nozzle diameter 3.5～4mm).In the air deflector shown in Figure 4: 1. inlet attack, 2. adjust pressure ring, 3. hollow shaft, 4. sealing ring, 5. ball bearing, 6. thrust bearing, 7. loam cake, 8. gear shaft, 9. gear-box.In the drill bit shown in Figure 5: 1. bit drills tooth, 2. carbide bit, 3. ball valve.

3. the center drilling rod is longer than about peripheral drilling rod 300mm, and this can prevent that peripheral drilling rod is to boring partially all around.(cylinder of middle casing and end casing is only advised drill rod axis position on the positive ground, referring to Fig. 6.Among Fig. 6: 1 is casing, and 2 is cylinder, and 3 are the guiding slips)

4. every pair of mutually PO long screw drill rod, its pitch identical (although the spiral shell footpath is different) thread rotary orientation is opposite, turns to also on the contrary when creeping into, so the direction of the movement of soil particles between drilling rod is same direction, successfully delivery port.Referring to Fig. 7.Three, the pile operation is followed successively by as shown in Figure 8 in proper order:

(1) bore down, (2) mud jacking, carry brill, (c is that the effect of mud jacking high-pressure osmosis forms and expands the bottom among the figure, and d is the cement paste that is pressed into) (3) descending reinforcing cage, (4) lapidation material, (5) mend slurry (a is for mending the slurry pipe among the figure), (6) vibrate (b is a vibrator among the figure).Through the S.P. that above operation is finished, pile strength can reach 23～30MPa, and bearing capacity of single pile is more than 4 times of general castinplace pile.Can not produce broken pile, necking.Four, outstanding advantage 1. pile-forming speeds of S.P. are fast.

The advantage that has kept long screw auger to work continuously, penetration rate are higher than the various rigs of mud off far away.Pile and pore-forming are once finished, and shorten the system stake cycle greatly.2. bearing capacity height.

With the pile body shape of quincunx (or other are non-circular), increased the stake side surface area, (way of 5～70MPa) slip castings has strengthened the stake side-friction force and the end load at an end to adopt high pressure simultaneously.The general castinplace pile of bearing capacity ratio improves more than 4 times, and not be used in perfusion concrete under the mud, so broken pile, necking can not take place.3.S.P. the length of reinforcing cage of method can be selected arbitrarily.

At the bottom of can the straight cutting hole in cement paste, (U.S. nineteen sixty patent US-2920455, auger boring grouting pile can only be put the bar dowel cage on the top of stake), thereby S.P. not only can do foundation pile, can also make the bending resistance slope protection pile, uplift pile, anchor pile.Long row shape S.P. (referring to Fig. 9) can be than circular stake arrangement of reinforcement more reasonably, and water sealing effect might as well.Among Fig. 9: 1. be steel bar concrete soil blocking pile (S.P. Ф 500-2 Ф 500), 2. spray water-seal pile (Ф 400) surely for the plain concrete of no-reinforcing-bar.The another example that Fig. 9 uses for S.P..4.S.P. rig can have multiple use.

Can be with just boring (as overstriking drilling rod steel pipe, reduce the helical blade width, then most of regolith only pushes that the fraction earth boring auger goes out) in Collapsible Loess District, counter-rotating is pressed into dirt or pulverized limestone, makes " lime-soil compaction pile " to eliminate collapsibility of loess.

In layer of sand that may earthquake liquefaction, get into desired depth after, counter-rotating is also injected solid sand cement slurry or other slurries simultaneously, makes it become the cement mortar stake, prevents layer of sand liquefaction.This method is more reliable than dark basic slip casting, because the position that it can be controlled the consumption of cement paste and admix layer of sand, does not fall flat and can not allow solid particle loaded fluid such as cement paste concentrate to be pressed into soft layer.

Claims

1. the present invention has adopted the unique special drilling machine design of design: long screw drill rod is combined into quincunx, long row's shape, dihedral etc. by the difformity requirement, drive simultaneously by special gear box, the drilling rod rotation direction and the thread rotary orientation of adjacent engagement are contrary, but rotating speed, pitch are all identical.This special drilling machine is placed in the piling pile frame and can gets out quincunx and other various non-circular holes.

2. second characteristic of the present invention are that boring, pile are once finished.The method of Cai Yonging is for this reason: be drilled into after the desired depth that high pressure injects cement paste at the bottom of the hole, this cement paste at the bottom of the hole and around soil layer infiltration retaining wall, reach until the slurries face and easily to collapse more than the hole site, carry and bore the back descending reinforcing cage and drop into the aggregate pile.For preventing that cement grout runs off, can insert that mending the slurry pipe repeatedly mends slurry.Grouting pressure is selected to adjust as required between 5～70MPa.Then select high pressure as making expanded bore pile with high-pressure osmosis soil layer or churning method.(changing drill bit bottom globe valve into the churning nozzle during churning).Stake top makes its concrete strength be not less than 20MPa through vibrating, and (general 20～25MPa) cement paste water/binder ratio are 0.5～0.55.

3. special drilling machine described in the right 1 also can be used for the campshed construction (gear-box that adopts this moment the long row of drilling rod shape to arrange) of pattern foundation pit supporting structure.Also can be used for ground stabilization: be unearthed with boring just in loess formation, counter-rotating is pressed into lime and earth mixtures is carried brill to the desired depth, makes lime-soil compaction pile and eliminates collapsibility of loess.During the process liquefaction layer of sand, can inject cement paste and other solid particle loaded fluids in counter-rotating, make " mortar pile ", the solid sand of mortar pile is more reliable than simple deep layer slip casting.Select the drilling rod of thick steel pipe narrow blades during as ground stabilization for use.