CN101135154A

CN101135154A - Blasting pile forming method for two-stage bottom expanding prefabricated pile body

Info

Publication number: CN101135154A
Application number: CNA2007101572991A
Authority: CN
Inventors: 周亚萍; 吴伟林
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-09-29
Filing date: 2007-09-29
Publication date: 2008-03-05

Abstract

The present invention relates to construction of building pile foundation engineering, and is especially blasting piling process of two-stage under-reamed prefabricated pile stem. The piling process includes the following steps: 1. immersing immersed tube with metal pile head into hardpan to design elevation; 2. taking out the metal pile head; 3. forming the lower base space through blasting and pouring the lower base with concrete; 4. setting the prefabricated solid lower pile stem with steel dowels into the immersed tube; 5. drawing upwards the immersed tube to designed distance, forming the upper base space, penetrating the steel dowels through the upper base space and connecting to the lower prefabricated pile stem, setting the prefabricated hollow upper pile stem into the immersed tube, and pouring the upper base; and 6. withdrawing the immersed tube and injecting cement mortar to the gap. The present invention has the advantages of high material strength utilizing rate, etc.

Description

The blasting pile-forming method of the bottom-enlarging prefabricated pile body of two-stage

Technical field

The present invention relates to a kind of construction of building pile foundation engineering, the piling method of the bottom-enlarging prefabricated pile body of particularly a kind of two-stage.

Background technology

According to the national regulation whole body be cast-in-place (be the pile body Cast-in-place concrete, base also is a Cast-in-place concrete) its base diameter ratio maximum value of expanded bore pile is limited in 3-3.5, and pipe sinking prefabricated steel concrete club-footed pile, this stake is the prefabricated concrete of pile body, the base Cast-in-place concrete, obviously this ratio 3-3.5 is broken, generally 3.5-5 can be reached,, requirement of engineering can't be satisfied although bearing capacity is bigger, particularly, the opposite end bearing capacity to give a discount 0.9 when bellout diameter during greater than 1.5 meters.For this reason, immersed tube prefabricated multistage under-reamed pile has appearred again.Existing multiple bearing capacity dish stake technology has two common ground, and first all is to expand the end with positive crossover-circulating type method pore-forming; Second all carries out pile without immersed tube expands the end.This two point-to-points load dish (at the bottom of the multistage expansion) stake is quite unfavorable, in other words, bring two problems, 1), national building code requirement, expand the base end load at the end with positive crossover-circulating type method pile and will take advantage of 0.45 coefficient, because have mud existence and pile bottom sediment to clean out, (Zhejiang Province's standard is 0.24 discount) gives a discount too big, though a plurality of bases are arranged, loss end load is very big; 2); without immersed tube; condition of construction can not get protection; positive in addition crossover-circulating type method is operation under water; expand bottom application worker situation and cannot see, the difficult measurement noted down, when also usually taking place to expand the end under water; top soil body a slice situation that falls down also happens occasionally; also have because the multistage stake of prior art all is the whole body Cast-in-place concrete, and that the intensity of Cast-in-place concrete is done is not high, and difficult quality guarantee; and in water, water concrete; the difficult control of quality adds that the pile capacity of a plurality of bases is all bigger, and its pile body diameter of above factor must be done greatlyyer; and this a plurality of base is afraid of that pile body diameter is big most; development test shows that pile body diameter increases, and its bearing capacity decay is very serious.

Summary of the invention

The problem that the present invention is directed to the prior art existence provides the blasting pile-forming method of the bottom-enlarging prefabricated pile body of a kind of two-stage, purpose is to improve the utilization rate and the reduction coefficient of the strength of materials, pile body and base good concentricity, obviously improve single pile bearing capacity, the reliable degree height, and can reduce the pile foundation engineering cost.

The blasting pile-forming method of the bottom-enlarging prefabricated pile body of two-stage of the present invention comprises following processing step: a, the immersed tube that has metal pile head is sunk to the hardpan design elevation; B, taking-up metal pile head; C, put into oil emulsion or tnt explosive from the immersed tube mouth, every 0.5m ³Consumption is the 1-5 kilogram, seals the immersed tube mouth behind the ignition charge, treat that explosive charge is finished after, open the article of sealing the immersed tube mouth and form lower base space, with inhaling indigenous equipment exhaustion hack, perfusion concrete cast lower bottom base; D, the lower end is had the following prefabricated solid pile body of joint bar, put into immersed tube until putting in place; E, on pull out immersed tube to setpoint distance H, expand end processing upper base space with extrusion equipment, joint bar is passed upper base space links to each other with following precast pile, last precast hollow pile body is put into the mesopore injection concrete of immersed tube from last precast pile, pour into a mould upper bed-plate; F, extract immersed tube, between the slit, inject cement paste.

Extrusion equipment among the described operation e is that hydraulic pressure props up disc shaping machine.

Setpoint distance H among the described operation e is 2-10 a times of base diameter.

The present invention is compared with prior art owing to do protection and rely on immersed tube, prefabricated in addition pile body up and down, and a series of technical measures such as upper bed-plate under the cast-in-place notes steel concrete, and have following advantage and good effect through evidence:

1, the ratio of base diameter and pile body diameter can reach 3.5-5, surpasses state-set standard;

2, the obvious raising of reduction coefficient can reach 0.9-1.0, improves strength of materials utilization rate;

3, do protection and rely on accurate positioning with immersed tube, make the Up/down base and the good concentricity of pile body up and down;

4, improve single pile bearing capacity, reliable degree height;

5, reduce the construction cost of building pile foundation engineering;

6, overcome the existing in prior technology defective.

Description of drawings

Fig. 1 a-Fig. 1 c is each operation status of processes schematic diagram of the present invention.

Among the figure 1, lower base space; 2, immersed tube; 3, following prefabricated solid pile body; 4, upper base space; 5, joint bar; 6, go up the precast hollow pile body.

The specific embodiment

Embodiments of the invention 1a-1c in conjunction with the accompanying drawings are described in detail.

The blasting pile-forming method of the bottom-enlarging prefabricated pile body of two-stage of the present invention comprises following processing step:

A, the immersed tube 2 that has metal pile head is sunk to the hardpan design elevation; B, taking-up metal pile head; C, put into oil emulsion or tnt explosive from the immersed tube mouth, every 0.5m ³Consumption is the 1-5 kilogram, seals the immersed tube mouth behind the ignition charge, treat that explosive charge is finished after, open the article of sealing the immersed tube mouth and form lower base space 1, with inhaling indigenous equipment exhaustion hack, perfusion concrete cast lower bottom base; D, the lower end is had the following prefabricated solid pile body 3 of joint bar, put into immersed tube until putting in place; E, on pull out immersed tube 2 to setpoint distance H, setpoint distance H is 2-10 a times of base diameter, propping up disc shaping machine with extrusion equipment hydraulic pressure expands the end and processes upper base space 4, joint bar 5 is passed upper base space 4 to link to each other with following prefabricated solid pile body 3 epimeres, then will go up precast hollow pile body 6 and put into the mesopore injection concrete cast upper bed-plate of immersed tube 2, as shown in Figure 1a from last precast pile; F, extract immersed tube, between the slit, inject cement paste.

The concrete steps of exhaustion hack are as follows among the above-mentioned operation c: inhale indigenous equipment with air and fetch earth, when only surplus a small amount of loosing during soil in the base, from immersed tube mouth pouring, pouring limit, limit sops up, and is clean up to fetching earth.

Claims

1. the blasting pile-forming method of the bottom-enlarging prefabricated pile body of two-stage is characterized in that it comprises following processing step: a, the immersed tube that has metal pile head is sunk to the hardpan design elevation; B, taking-up metal pile head; C, put into oil emulsion or tnt explosive from the immersed tube mouth, every 0.5m ³Consumption is the 1-5 kilogram, seals the immersed tube mouth behind the ignition charge, treat that explosive charge is finished after, open the article of sealing the immersed tube mouth and form lower base space, with inhaling indigenous equipment exhaustion hack, perfusion concrete cast lower bottom base; D, the lower end is had the following prefabricated solid pile body of joint bar, put into immersed tube until putting in place; E, on pull out immersed tube to setpoint distance H, expand end processing upper base space with extrusion equipment, joint bar is passed upper base space links to each other with following precast pile, last precast hollow pile body is put into the mesopore injection concrete of immersed tube from last precast pile, pour into a mould upper bed-plate; F, extract immersed tube, between the slit, inject cement paste.

2. the blasting pile-forming method of the bottom-enlarging prefabricated pile body of two-stage according to claim 1 is characterized in that the extrusion equipment among the described operation e is that hydraulic pressure props up disc shaping machine.

3. the blasting pile-forming method of the bottom-enlarging prefabricated pile body of two-stage according to claim 1, it is characterized in that setpoint distance H among the described operation e be base diameter 2-10 doubly.

4. the blasting pile-forming method of the bottom-enlarging prefabricated pile body of two-stage according to claim 1, the concrete steps that it is characterized in that exhaustion hack among the described operation c are as follows: inhale indigenous equipment with air and fetch earth, when only surplus a small amount of loosing during soil in the base, from immersed tube mouth pouring, pouring limit, limit sops up, and is clean up to fetching earth.