CN102660957A - Foundation pit supporting construction method for soft soil zone - Google Patents

Abstract

The invention relates to a foundation pit supporting method in building construction, in particular to a foundation pit supporting construction method for a soft soil zone. A rectangular section supporting pile is used, and construction is realized by a pile jumping method. The construction method includes the specific steps: vibrating, pressing and sinking a pile tube into a soil layer under the action of a vibration hammer by the aid of a vibration sinking-tube piling machine; starting a pumping device when reaching designed elevation, pumping pile materials into a pile material delivery pipe; starting vibration and up-pull when the pressure of the pump reaches 7MPa; controlling the up-pull speed of the pile tube to range from 0.8m/min to 1m/min; continuing to pull up the pile tube; timely filling the pile materials in a space reserved after pulling up the pile tube; pulling the bottom end of the pile tube out of the ground to form a pile; lifting a reinforcement cage by a lifter; planting the reinforcement cage into a plain concrete pile under the action of a vibration device to form a reinforced concrete supporting pile; and performing soil excavation and top beam construction after concrete reaches 75% of designed strength. Reinforcements can be saved, mud discharge is avoided, environmental pollution is decreased, and construction is safe and fast.

Description

The soft clay area base pit stand construction

Technical field

The present invention relates to foundation pit supporting method in the building operations, specifically is a kind of soft clay area base pit stand construction.

Background technology

At present, high level and super large space structure building thing are increasing, and the excavation of foundation pit degree of depth and area are increasing.In order to strengthen foundation ditch periphery intensity, prevent local or large-area landslide, need make supporting and protection structure to its periphery.In soft clay area, when the excavation of foundation pit degree of depth is 8 ~ 12m, the drill-pouring soldier pile supporter system that traditional pattern foundation pit supporting structure is commonly used, exist expensive, the cycle long and problem such as environment pollution.

Summary of the invention

The present invention is intended to solve the problems referred to above that the soft clay area cutting depth is the foundation pit support construction existence of 8 ~ 12m; And provide under the premise that security is guaranteed a kind of; Can effectively reduce pattern foundation pit supporting structure cost and cost; Accelerate speed of application, solve the soft clay area base pit stand construction of problem of environmental pollution.

The technical scheme that the present invention solves said problem employing is:

A kind of soft clay area base pit stand construction, it adopts the square-section soldier pile, carries out the soldier pile construction by jumping pile construction method, and concrete steps are:

A. pile-forming machine perching in the embedded bar concrete shoe of design stake position, utilizes the vibrator sunk pile machine; Under the effect of vibrating hammer, the stake pipe shaken to press and sink to soil layer, when arriving design elevation, start pumping equipment earlier; Flapper-type stake point is opened automatically, makes material of body of a pile get into the material of body of a pile carrier pipe, makes the pressure of pump reach 7MPa and begins to pull out in the vibration; Material of body of a pile flows out, and pulls out rate controlled at 0.8～1m/min on the stake pipe, pulls out on the stake pipe continues; The space that stays after pulling out on the timely filling pile pipe of material of body of a pile, treat that a stake pipe bottom goes out ground after, pile body forms;

B. utilize the crane gear install reinforcing cage, under the vibratory equipment effect, reinforcing cage implanted in the plain concrete pile, form the steel concrete soldier pile, treat concrete reach design strength 75% after carry out soil excavation Guan Liang construction.

Compared with prior art, outstanding effect of the present invention is:

1. substitute present traditional circular cross-section soldier pile with the rectangle stake and can save reinforcing bar.Concrete calculating as follows (referring to Fig. 1, Fig. 2):

Generally press steel concrete normal section flexural member during the bored pile Reinforcement Calculation and calculate, when the cross section was circle, this computation schema considered that any direction all will have identical bending resistance, and design formulas is selected for use:

, M is the moment of flexure that pile receives, Be coefficient,

Be characteristic value of concrete compressive strength, A is the cast-in-place concrete pile cross-sectional area, and r is the radius of circular cross-section, f _yBe reinforcing bar tensile strength design load, A _SBe whole tensile reinforcement sectional areas, r _sThe radius of longitudinal reinforcement place circumference, For corresponding to long-pending central angle of pressure zone concrete section and the ratio of 2 π,

Be the ratio of longitudinal tensile area of reinforcement with whole longitudinal reinforcement section area, when

＞0.625 o'clock, get

=0, but the tension side of retaining earth concrete castinplace pile is certain, wherein there is 40% reinforcing bar not drawn.If simple for practicing thrift reinforcing bar, can with drawn main muscle 1 centralized configuration in the retaining soil face tensile region of stake 2 edges, and dispose an amount of distributing bar 3, but this kind reinforcement manner hangs the increase great difficulty to reinforcing cage, and reinforcing cage is forbidden dislocation or reverse.

For the rectangle stake, when only considering to be furnished with the longitudinal tensile reinforcing bar, design formulas is selected for use

, M is the moment of flexure that pile receives, f _yBe reinforcing bar tensile strength design load, A _SBe whole tensile reinforcement sectional areas, γ _sBe coefficient, h _OBe effective depth of section, promptly the tensile reinforcement centre of form is exactly the meaning of the arm of force to the distance in concrete compression district.Circular stake is along the circumference uniform reinforcement, changes along the reinforcing bar arm of force length of circumference, varies, and centroidal line is near more apart from the concrete compression district, and action of steel bars can not be brought into play more, has just wasted; And the rectangle stake arm of force all is the same; Reinforcing bar can play one's part to the full, and main muscle about 50% is saved in the circular stake of comparable peripheral uniform reinforcement, considers suitably to dispose the appropriate structuring reinforcing bar at non-tension side; Total longitudinal stress reinforcing bar amount still can save 30%～40%, and the numerical value of this saving is appreciable.

2. utilize the vibrator sunk pile machine, under the effect of vibrating hammer, the stake pipe shaken to press and sink to soil layer, can avoid mud emission, reduce environment pollution.

Description of drawings

Fig. 1 is a circular cross-section supporting and protection structure calculation diagram.

Fig. 2 is a square-section supporting and protection structure calculation diagram.

Fig. 3 is a tubular structure sketch map.

Fig. 4 is an A-A schematic cross-section among Fig. 3.

Fig. 5 is that reinforcing cage hangs view.

Fig. 6 is the foundation pit supporting pile layout plan.

Among the figure: 1-is drawn main muscle; The 2-tensile region; The 3-distributing bar; 4-stake pipe; 5-material of body of a pile carrier pipe; The 6-crane gear; The 7-reinforcing cage; 8-steel concrete soldier pile; 9-builds outer contour.

The specific embodiment

Further set forth the present invention below in conjunction with embodiment, purpose only is to understand better content of the present invention.The example of therefore, being lifted does not limit protection scope of the present invention.

Referring to accompanying drawing, the concrete steps of soft clay area base pit stand construction are:

1. calculate according to the excavation of foundation pit degree of depth, geological conditions and surrounding enviroment etc. and confirm soldier pile design parameters and soldier pile layout plan, carry out the soldier pile construction then.Soldier pile adopts the square-section soldier pile, and construction is adopted and jumped pile driving construction.

2. pile-forming machine perching, the embedded bar concrete shoe of design stake position is shaken stake pipe 4 to press under the vibrating hammer effect of vibrator sunk pile machine and is sunk to soil layer, when arriving design elevation; Start pumping equipment earlier, make material of body of a pile get into material of body of a pile carrier pipe 5, make the pressure of pump reach 7MPa and begin to pull out in the vibration; Material of body of a pile flows out, and pulls out rate controlled at 0.8m/min on the stake pipe, pulls out on stake pipe 4 continues; The space that stays after pulling out on the timely filling pile pipe 3 of material of body of a pile, treat that stake pipe 4 bottoms go out ground after, pile body forms.

3. utilize crane gear 6 install reinforcing cages 7, under the vibratory equipment effect, reinforcing cage 7 is implanted in the plain concrete pile, form steel concrete soldier pile 8.Treat concrete reach design strength 75% after carry out soil excavation Guan Liang construction.

Claims (1)

1. a soft clay area base pit stand construction is characterized in that, adopts the square-section soldier pile, carries out the soldier pile construction by jumping pile construction method, and concrete steps are:

A. pile-forming machine perching in the embedded bar concrete shoe of design stake position, utilizes the vibrator sunk pile machine; Under the effect of vibrating hammer, the stake pipe shaken to press and sink to soil layer, when arriving design elevation, start pumping equipment earlier; Flapper-type stake point is opened automatically, makes material of body of a pile get into the material of body of a pile carrier pipe, makes the pressure of pump reach 7MPa and begins to pull out in the vibration; Material of body of a pile flows out, and pulls out rate controlled at 0.8～1m/min on the stake pipe, pulls out on the stake pipe continues; The space that stays after pulling out on the timely filling pile pipe of material of body of a pile, treat that a stake pipe bottom goes out ground after, pile body forms;

B. utilize the crane gear install reinforcing cage, under the vibratory equipment effect, reinforcing cage implanted in the plain concrete pile, form the steel concrete soldier pile, treat concrete reach design strength 75% after carry out soil excavation Guan Liang construction.

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