Steel pipe locking anchor rod construction method
Technical field
The present invention relates to the prestressed anchor technical field of construction, relate in particular to steel pipe locking anchor rod construction method.
Background technology
[0002] along with development and national economy, highrise building is more and more, and deep foundation ditch is also more and more.The national regulation regulation, all deep foundation ditchs all must be done pattern foundation pit supporting structure.The conventionally form of pattern foundation pit supporting structure has: various ways such as soldier pile, soil nailing wall.The horizontal thrust on the foundation ditch limit that soil nailing wall, soldier pile receive will be resisted by the horizontal pull of prestressed anchor, so support systems such as soldier pile, soil nailing wall all will be established prestressed anchor, makes anchor pole become as a whole drawknot body with the soil body, accomplishes economical rationality.
But having following difficult point: ⑴ pore-forming on soft foundation, saturated soil, grains of sand soil, silty clay in the prestressed anchor construction is a difficult problem, and this is the key in the construction technology; ⑵ in the construction work, because construction is basic earlier, so in case commencement of works requires foundation pit dewatering fast, excavation is fast, so the duration is short; ⑶ though adopted dewatering measure, near more in the precipitation from the foundation ditch limit, easy more the oozing down of water in the soil body, water is difficult to ooze down in the soil body on more than 10 meter on foundation ditch limit, because excavation speed is fast, the time does not allow, so water can't be penetrated in the gutter fully; ⑷ general soil body upper strata major part is miscellaneous fill, grains of sand soil, silty clay; So a little less than the permeability of water; Just as sponge, can keep the moisture causes water here and can not in time be penetrated into the gutter, so the soil body that exists is saturated soil mostly; And saturated soil often can't pore-forming, manual pore-forming and the machine drilling hole that is prone to collapse; ⑸ prestressed anchor design generally all more than 10m, penetrates the soil body slipping face, anchors in the stable soil layer, could produce the effective prestress pulling force like this.Ill-conditioned, the hole depth of the soil body when therefore, having brought up the pore-forming of prestressed anchor, be prone to cave in, easy-formation not.Do not have qualified hole, carry out next procedure with regard to it doesn't matter---insert bolt grouting.
Hole forming method commonly used at present is luoyang spade manual pore-forming method and machine drilling sleeve pipe follow-up hole forming method.The shortcoming of luoyang spade manual pore-forming method is that efficient is extremely low, the grains of sand are native shapeless, at all can't pore-forming; Machine drilling sleeve pipe follow-up hole forming method is that the termination of drilling rod and sleeve pipe is equiped with alloy tool steel bit, has revolution and impacts the double-acting function of creeping into, and sleeve pipe and drilling rod creep into simultaneously, realize sleeve pipe follow-up retaining wall, needn't adopt mud off; Water under high pressure pumps in drilling rod, flows out from cavity between drilling rod and sleeve pipe, and drilling cuttings earth is taken out of, forms bolthole, and being suitable for the pore-forming aperture is foundation ditch hole wall prestress anchorage cable or the prestressed anchor supporting construction of 150 mm.This hole forming method complex process, require high, long in time limit and noise is big, cost is high to work plane, only the 1m cost of holing is just between 280 ~ 300 yuan.
Summary of the invention
Technical problem to be solved by this invention provides the steel pipe locking anchor rod construction method that a kind of technology is simple, cost is low.
For addressing the above problem, steel pipe locking anchor rod construction method of the present invention may further comprise the steps:
⑴ adopt conventional method to layout;
⑵ roof-bolter is in place;
⑶ guiding steel pipe, twisted steel anchor rod that said roof-bolter will lead in the steel pipe locking prestressed anchor are squeezed into the said soil body to the design length of layouting;
⑷ mix the system cement grout: in 425 grades of Portland cements, mix the accelerating admixture of its weight 5%, and to make the water/binder ratio of cement grout be 0.45 ~ 0.5, proportion is 1.7 ~ 1.8;
⑸ be under the condition of 0.5 ~ 3MPa at pressure, injects said cement grout through grouting pump to said guiding steel pipe, in the hole that said guiding steel pipe locking prestressed anchor forms in the said soil body, has cement grout to flow out and can stop slip casting;
⑹ behind the soil solidifying 7 days, and intensity reaches 75% and draws the power of dialling to detect to said guiding steel pipe locking prestressed anchor when above, and amount detection is no less than 3%, draws to dial the power value and get final product greater than design load.
Guiding steel pipe locking prestressed anchor among the said step ⑶ comprises two butt welding guiding steel pipe, twisted steel anchor rod and reaming reinforcing bar together; Said each guiding steel pipe is equipped with the said reaming reinforcing bar that is the tip of falling the Eight characters, and the front end of said two guiding in the steel pipes is provided with three and arranges and equidistantly be quincuncial several injected holes; Said twisted steel anchor rod and said two guiding steel pipes weld together at forward terminal.
The weld of said two butt welding guiding steel pipe together is evenly equipped with three said reaming reinforcing bars along the pipe outer wall of said guiding steel pipe.
The bore dia of said injected hole is 6mm ~ 9mm.
Said twisted steel anchor rod is formed by 2 isodiametric screw-thread steel single-selded lap joints, and fusion length equals 10 times of said screw-thread steel diameter.
The present invention compared with prior art has the following advantages:
1, owing to is provided with guiding steel pipe and the twisted steel anchor rod that welds together among the present invention; And be provided with the reaming reinforcing bar that is the tip of falling the Eight characters; Therefore; Surrounding soil strengthens its anchor pole rub cross section so that can make anchor pole fixed with the loosening soil body and slurry when injecting slurries on every side in the loosening anchor pole 150mm diameter when guiding steel pipe and twisted steel anchor rod are hammering into the soil body.
2, be quincunx injected hole owing to being provided with among the present invention, therefore, through the anchoring section of slip casting formation anchor pole, grouting reinforcement produces frictional resistance, generates pulling force in saturated soil and grains of sand soil, reaches pore-forming, prestressed reinforcement placement, the one-time formed purpose of slip casting.
3, the present invention is with in anchor pole, the soil nailing construction technology; Two independent working procedures: pore-forming → insert anchor pole to be integrated; Therefore; Not only technology is simple, and has solved this difficult problem of building anchor pole in the generally acknowledged deep foundation pit support of industry, soil nailing pore-forming difficulty in subgrade soil, saturated soil, grains of sand soil, silty clay.
4, simple, light, the required work plane of present device is little; Noise, pollute little, with low cost; Be applicable to miscellaneous fill (refuse soil), powder fine sand, saturated soil, subgrade soil layer, be specially adapted to the geology (the Northwest's geology generally all is grains of sand soil, silty clay) of the Northwest.
Even 5 groundwater table are high, construction period is tight, and the foundation ditch excavation of will seeking quickness in well digging dewatering, although shipwreck to leak out to deep-well, adopts technology of the present invention also can directly throw into, carries out anchor bolt construction.
6, the present invention builds the auspicious scape 1# of worker building base pit engineering, " Gansu Tumour Hospital's outpatient service " complex building base pit engineering, builds the practical application in the old building transforming base pit engineering of endangering for high-storey business, the cooperation South Road worker of Gansu Province the 8th construction engineering corporation man-hour in solid 116# high-rise residential building deep foundation pit support soldier pile prestressed anchor engineering, Gansu through the orchidization west; Effect is remarkable, has obtained owner's favorable comment.
Description of drawings
Do further detailed explanation below in conjunction with the accompanying drawing specific embodiments of the invention.
Fig. 1 is a structural representation of the present invention.
Among the figure: 1-guiding steel pipe, 2-twisted steel anchor rod, 3-reaming reinforcing bar, 4-injected hole.
The specific embodiment
Steel pipe locking anchor rod construction method may further comprise the steps:
⑴ adopt conventional method to layout.
⑵ roof-bolter is in place.
⑶ guiding steel pipe 1, twisted steel anchor rod 2 that roof-bolter will lead in the steel pipe locking prestressed anchor are squeezed into the soil body to the design length of layouting.
Wherein: guiding steel pipe locking prestressed anchor comprises two butt welding guiding steel pipe 1, twisted steel anchor rod 2 and reaming reinforcing bar 3 (referring to Fig. 1) together.Each guiding steel pipe 1 is equipped with the reaming reinforcing bar 3 that is the tip of falling the Eight characters, and the front end of two guiding in the steel pipe 1 is provided with three and arranges the injected hole 4 that equidistantly to be quincuncial several bore dias be 6mm ~ 9mm; Twisted steel anchor rod 2 and two guiding steel pipe 1 welds together at forward terminal.
The weld of two butt welding guiding steel pipe 1 together is evenly equipped with three reaming reinforcing bars 3 along the pipe outer wall of guiding steel pipe 1.Twisted steel anchor rod 2 is formed by 2 isodiametric screw-thread steel single-selded lap joints, and fusion length equals 10 times of the screw-thread steel diameter.
⑷ mix the system cement grout: in 425 grades of Portland cements, mix the accelerating admixture of its weight 5%, and to make the water/binder ratio of cement grout be 0.45 ~ 0.5, proportion is 1.7 ~ 1.8.
Wherein: the requirement that accelerating admixture satisfies " sprayed mortar is used accelerating admixture " JC477-92 gets final product.
⑸ be under the condition of 0.5 ~ 3MPa at pressure, injects cement grout through grouting pump to guiding steel pipe 1, in the hole that guiding steel pipe locking prestressed anchor forms in the said soil body, has cement grout to flow out and can stop slip casting.
⑹ behind the soil solidifying 7 days, and intensity reaches 75% and draws the power of dialling to detect to guiding steel pipe locking prestressed anchor when above, and amount detection is no less than 3%, draws to dial the power value and get final product greater than design load.