CN103938609A - Composite foundation composed of rubble/ sand inverted filter layer and porous concrete piles and treatment method - Google Patents
Composite foundation composed of rubble/ sand inverted filter layer and porous concrete piles and treatment method Download PDFInfo
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Abstract
The invention discloses a composite foundation composed of a rubble/sand inverted filter layer and porous concrete piles and a treatment method. The exterior structure of the foundation is the rubber/sand inverted filter layer, and the interior of the foundation is porous concrete. The pile diameter is 0.3 m-0.8 m, and the thickness of the rubble/ sand inverted filter layer outside the piles is 0.2 m-0.4 m. After underwater maintenance for 28 days, the compressive strength of the porous concrete is not lower than 5 MPa, the permeability coefficient is not lower than 5 mm/s, the pile spacing is 3-5 times of the pile diameter, and the porosity rate of the porous concrete is greater than 20 percent. The treatment method of the foundation comprises the steps that according to the requirements for foundation settlement and bearing capacity, the pile diameter, the pile spacing, the foundation reinforcement range, the reinforcement depth, the pile arrangement mode, the amount of packing in pile holes and the thickness of pile top granular materials or wet clay are determined, and piles are constructed. According to the composite foundation, the problem that the porous concretes are blocked by slurry is effectively weakened; the rubble/sand inverted filter layer plays a role in water permeability and inverted filtering, and therefore the piles can be drained continuously and effectively in the composite foundation.
Description
Technical field
The invention belongs to field of civil engineering, relate to a kind of rubble/sand loaded filter-porous concrete pile composite foundation and processing method.
Background technology
The composite foundation that the pile foundation of porous concrete material composition forms can carry certain vertical load in the time processing soft soil foundation, there is certain bearing capacity of single pile and Bearing Capacity of Composite Foundation, porous concrete pile body can be brought into play the permeable anti-filter of discrete material in conjunction with discrete material piles such as broken stone pile and the advantage such as concrete pile intensity and toughness is large, Chinese patent CN102296593A discloses a kind of cylindrical compound concrete macadam placepile and construction technology thereof, this construction process of bored concrete pile complexity, inner concrete compaction is waterproof, and whole pile body drainage effect is undesirable.Chinese patent CN103452093A mentions a kind of pervious concrete broken stone pile tandem type composite foundation, because the porous concrete of new mixing is easily emanated under water environment and when vibration is constructed, cement paste and aggregate depart from and cause inhomogeneous being distributed in porous concrete of cement paste, blocking portion hole, makes porous concrete lose pervious function.
It is the moulding in order to ensure pile body that replacement stone pile composite foundation pile body adopts vibration sinking tube construction, there is not broken pile, the disease of undergauge, the time of vibration processes can not be too short, pipe-pulling speed tube drawing process can not be too fast, tube-sinking cast-in-situ pile bore forming pipe-pulling speed should be by the uniform velocity controlling, pipe-pulling speed should be controlled at 1.2m/min～1.5m/min left and right, when meeting mud or mucky soil, pipe-pulling speed should suitably slow down, and the soil of undue disturbance stake week of too much meeting that vibrates, be unfavorable for bearing capacity of single pile in composite foundation and the bearing capacity of composite foundation, vibrating in addition the too much soil body is equivalent to smear one deck impervious material in drainage channel outside, be unfavorable for pile body draining.
Mostly porous concrete is to work in the fluid environment that is rich in mud as draining, and the obstruction of mud can make the water permeability of the porous concrete that porosity is lower have a greatly reduced quality.The obstruction of porous concrete as shown in Figure 4.Iowa State University research shows: in the time of the porosity of porous concrete, the certain hour if porous concrete is worked under the fluid of composite sludge, porous concrete will lose drainage effect, as shown in Figure 5, the porous concrete specimens porosity of three kinds of porosity is respectively: 15%, 20%, 25%, with the fluid that is rich in silt by porous concrete specimens inside, each circulation is passed through concrete with the fluid of fixed volume V, then test its transmission coefficient with clear water, transmission coefficient is as shown in ordinate in Fig. 5.Experimental result shows, when the porosity of porous concrete is when large (25%), the ability that opposing is stopped up is good, and when porosity (15%) porous concrete at the basic water permeability of losing after 8 circulations.If it is large that the hole of porous concrete becomes, the ability of keeping out the environment that is rich in slurry fluid will strengthen.In addition make by changing the working environment of porous concrete the draining that porous concrete stake can continuous and effective.For example, if french drain rubble is anti-filter discharge structure in the road structure drainage system of Drainage Base, we can expect thus, the drainage effect of discrete material rubble/sand is better than the drainage effect of porous concrete, if apply discrete material in porous concrete stake periphery, the anti-mud blocking ability of porous concrete stake can improve.
Summary of the invention
For solving above-mentioned the deficiencies in the prior art, the invention provides a kind of rubble/sand loaded filter-porous concrete pile composite foundation and processing method; Solved under water and immersed tube constructs that the pile body that causes stops up and the course of work in because of the sand pile body draining inefficacy causing of depositing, pipe-pulling speed while having improved vibration sinking tube construction, reduce the disturbance of stake week soil, be conducive to improve bearing capacity of single pile and Bearing Capacity of Composite Foundation, accelerate construction speed, reduce construction cost.
The technical purpose the present invention relates to has:
The anti-obstruction of macroporosity does not disperse the design of Self-leveling porous concrete under water; Improve pipe-pulling speed by the mobility that changes vibration sinking tube filler; Porous concrete stake week is arranged rubble loaded filter, and pile body has anti-mud blocking ability; Rubble loaded filter-porous concrete pile composite foundation pile body is arranged, rubble loaded filter-porous pile composite foundation construction method.
To achieve these goals, the present invention adopts following technical scheme:
A kind of rubble/sand loaded filter-porous concrete pile composite foundation, comprise pile body, described pile body external structure is rubble/sand loaded filter, inside is porous concrete, and the diameter of pile body is 400～800mm, and the outside rubble/sand loaded filter of pile body thickness is 200～400mm, porous concrete under water maintenance 28d compressive strength is not less than 5MPa, transmission coefficient is not less than 5mm/s, and pilespacing is doubly stake footpath of 3-5, porous concrete porosity > 20%.
Described pilespacing is to silt or sandy soil ground, and pilespacing is not more than 4.5 times an of footpath; Cohesive soil ground is not more than to 3 times an of footpath.
Described pile body adopts square, rectangle, triangle or radioactivity to arrange.
Porous concrete porosity is greater than 20%, and the peripheral rubble loaded filter of laying of porous concrete, makes the pile body also can continuous and effective draining under the fluid environment that is rich in mud, accelerates the consolidation draining of foundation soil.
A kind of porous concrete, comprises following raw material: gather materials, cement, mineral admixture, water and thickener; In mass ratio, cement and mineral admixture sum/gather materials=0.19～0.23; Described mineral admixture is SILICA FUME and nano-calcium carbonate; Micro-wollastonite powder accounts for 0%～10% of cement; Nano-calcium carbonate accounts for cement 0～1%, and thickener accounts for 2%～4.5% of cementitious material; The graded broken stone that to gather materials for particle diameter be 5-20mm; The mass ratio of water and cementitious material is 0.25～0.35.
A preparation method for porous concrete, master operation is weigh batching and stirring, step is as follows:
1) method of measurement: cement, water, gathers materials, micro-wollastonite powder, nano-calcium carbonate, thickener are all measured by mass;
2) stir: the water mix and blend 1min that large particle diameter porous concrete adopts that first three-step approach stirs gathering materials under water, micro-wollastonite powder, nano-calcium carbonate, thickener and total water amount mass ratio are 25%; Then the water of cement and total consumption 30% is joined and in mixture, stir 1min; The water that is finally 45% by total consumption mass ratio adds and in mixture, stirs 1min;
3) after stirring, get final product discharging, transport, is used; The porous concrete time of building should in the time of concrete mixing, the time of adding water starts timing within an hour for the first time.
The processing method of above-mentioned rubble/sand loaded filter-porous concrete pile composite foundation, comprises the steps:
(1) determine stake footpath and pilespacing according to foundation settlement and requirement for bearing capacity, the thickness of amount of filler, stake top granular materials or damp clay in ground stabilization scope, reinforcement depth, pile body arrangement, stake hole;
(2) parameter obtaining according to step 1), in the position that pile body is set, to overlap effective leading truck fixes, the casing length of rubble/sand and porous concrete is 1.15 times of designing pile length, the sleeve pipe of rubble/sand is squeezed in soil to predetermined reinforcement depth, then in the sleeve pipe of rubble/sand, settle the sleeve pipe of porous concrete under water, the diameter of the sleeve pipe of rubble/sand is pile body diameter, inner sleeve is porous concrete stake core diameter, drop into porous concrete until flush with sleeve pipe place suitable for reading at inner sleeve, outer sleeve drops into rubble/sand, condiment is to the sleeve pipe place that flushes suitable for reading, two sleeve pipes pull up simultaneously, vibration limit, limit tube drawing plays ground and pile, pipe-pulling speed is 3～10m/min, pile pipe is extracted behind ground, confirm to bind with granular materials or damp clay after its composite design requires, next pile construction is carried out in telephone-moving.
Definite method of the reinforcing scope of the ground described in step 1) is as follows: reinforcing scope is greater than foundation bed area and is no less than 1～3 campshed in basic outer rim increase;
Pile body method for arranging described in step 1) is as follows: need carry out large area (﹥ 1000m
2) full hall is while processing, pile body adopts equilateral triangle to arrange; For single footing or strip foundation, stake position adopts square, rectangle, or isosceles triangle is arranged; For circular foundation or ring foundation, adopt radioactivity to arrange.
The spacing of the rubble/sand loaded filter porous concrete stake described in step 1) determines that method is as follows: pile spacing is not more than 4.5 times of rubble/sand loaded filter porous concrete stake diameter.
Definite method of the ground stabilization degree of depth described in step 1) is as follows:
1., in the time of the buried depth ﹤ of soil supporting layer 10m, the buried depth that reinforcement depth is bearing stratum, the power of holding is squeezed in pile body bottom
Layer;
2., in the time of soil supporting layer buried depth >=10m, for the engineering of Deformation control, reinforcement depth should meet rubble/sand loaded filter-porous concrete pile composite foundation and be out of shape the requirement that is no more than structure foundation allowable strain, for the engineering of pressing stability control, reinforcement depth should be greater than the degree of depth of most dangerous slip surface face;
3., in Liquefaction Foundation, reinforcement depth should adopt by the pertinent regulations of existing national standard " seismic design provision in building code " GB50011-2010;
4., stake longly can not be less than 4m, and be no more than 30m.
Stake footpath described in step 1) determines that method is as follows: while adopting immersed tunnelling method pile, diameter is 0.3～0.8m, and the diameter of saturated cohesive soil ground is 0.5～0.8m.
Filler method for determination of amount in stake hole described in step 1): the amount of filler in stake hole equals a pore volume and is multiplied by fullness coefficient, and fullness coefficient gets 1.2～1.4;
The thickness of the rubble/sand loaded filter porous concrete stake top hardcore bed described in step 1) is 0.3～0.5m.
Step 2) described sequence of construction is: should in the middle of peripheral or two side direction, carry out sand foundation, to cohesive soil ground should be from centre to the periphery or every applying work.
Step 2) described leading truck is perpendicular to the ground, and vertical missing≤1.5%, pile position and design attitude deviation≤0.05m, stake footpath deviation≤0.02m, long deviation≤0.1m.
In step 2) complete after, detect the construction quality of pile body, comprise following content:
(1), after construction period and construction finish, check the construction note of stake; Check sleeve pipe heave amplitude and speed;
(2) detection of construction quality of pile body adopts Single Pile Load test, adopts dynamic sounding to detect to pile body, and inter-pile soil is adopted to standard injection, static sounding, and dynamic sounding or other home position testing methods detect;
(3), when ground final acceptance of construction, bearing capacity examination adopts composite foundation loading test;
(4) composite foundation loading test is no less than 5 ‰ of total amount of pile, and the Bearing Capacity of Composite Foundation testing site of each single building is no less than 3 points.
Work progress except observing relevant code regulation, should also be noted that following some:
1. before formal construction, should carry out pile test, with the reasonability of demonstration test parameter, in the time finding to meet design requirement, design need be tested or change to relevant parameters again
2. while formally construction, long, the pilespacing of stake, stake footpath, filler match ratio, the amount of filler that will propose in strict accordance with design and test definite pile pipe pipe-pulling speed and height, the construction parameters such as the operating current of motor are constructed, to guarantee all continuitys of even pile body of extruding.
Beneficial effect of the present invention:
1, pile body internal material is porous concrete, outside is rubble/sand loaded filter, rubble/sand loaded filter can effectively weaken porous concrete stake by the problem of blocking up of mud, and rubble/sand loaded filter has been brought into play the advantage of permeable anti-filter, makes the pile body can continuous and effective draining in composite foundation.
2, in composite foundation, porous concrete is as rigid material, and rubble/sand is as discrete material, and the advantage of rigid pile has been brought into play in the combination of rigid pile and granular pile, simultaneously, this porous concrete is discrete material, and yield stress own is little, and plastic viscosity is moderate, the Self-leveling character of porous concrete can provide lateral pressure for discrete material, while making pile body construction, can not cause broken pile, necking down, vibration sinking tube pipe-pulling speed is accelerated, can be promoted to 3-10m/min; Reduced the disturbance to stake week soil, be conducive to improve bearing capacity of single pile and Bearing Capacity of Composite Foundation, porous concrete has the performance of anti-dispersion under water, can reduce the requirement to construction environment, is conducive to reduce construction cost.
3, adopt the porous concrete of large particle diameter material composition, this concrete has macroporosity, and porosity communication is effective, at the peripheral one deck rubble/sand loaded filter that increases of porous concrete, thereby the persistence drain function that ensures pile body, has solved concrete and has stopped up the disadvantageous problem that pile body is brought.
4, for the porous concrete that solves common new mixing does not have scour resistance under water, adding anti-dispersant and nano-calcium carbonate to improve concrete water mud rheological property, is that the cement paste of porous concrete inside has low yield stress and suitable plastic viscosity.Thereby cement paste has water resistant to be washed away, can under water environment, be wrapped in the surface of porous concrete aggregate, strengthen the compliance of porous concrete to construction environment.
Brief description of the drawings
Fig. 1 is rubble/sand loaded filter-porous concrete stake schematic diagram;
Fig. 2 is that pile body is arranged schematic diagram;
Fig. 3 is pile body arrangement form figure;
The schematic diagram of the obstruction of Fig. 4 porous concrete;
Fig. 5 porous concrete blocking experiment curve;
Wherein, 1, rubble reverse osmosis layer, 2, porous concrete.
Detailed description of the invention
Below in conjunction with accompanying drawing and example, the present invention is further described.
Embodiment 1
Certain project is positioned at impact Plain, the Yellow River, belongs to areas formerly flooded by the Huanghe River.Geological condition has silt, clay, silt, clay from top to bottom.Groundwater table is in 3m left and right, and underground water is very abundant.For reducing settlement amount after construction, ensure the stable of building, design adopts rubble/sand loaded filter-porous concrete pile composite foundation to process soft foundation.
As shown in Figure 1, 2, a kind of rubble/sand loaded filter-porous concrete pile composite foundation, comprises pile body, and pile body outside is rubble/sand loaded filter, and rubble/sand loaded filter can stop that mud, to porous concrete stake infiltration, does not lose drainage simultaneously.Inside is porous concrete material, ensures permeable time to have certain strength and stiffness, is conducive to improve pipe-pulling speed, reduces the disturbance to stake week soil, improves the bearing capacity of composite foundation.Rubble/sand loaded filter is in conjunction with porous concrete material form compound foundation.
This ground treatment step is specific as follows:
Pile body adopts arranged in squares as shown in Figure 3, and according to mechanical execution condition, a stake footpath is 0.5m, and long according to geological conditions stake is 9m, 4 times of rubble/sand loaded filter-porous concrete stake diameter; Through overtesting, this arrangement meets bearing capacity of foundation soil and distortion meets the demands.Processing method is: determine according to site condition, bridges and culverts ground stabilization is reinforced for full hall, reinforces area and is greater than foundation bed area and increases by 1 campshed in basic outer rim.Determine by field trial, the fullness coefficient of stake pore volume gets 1.2.Rubble/sand loaded filter filler is rubble, and mud content is less than 5%.The maximum particle of crushed stone is not more than 50mm.The hardcore bed that a layer thickness is 300mm should be laid in stake top.
Specific construction technique is: in the position that pile body is set, will overlap effective leading truck and fix; The casing length of rubble and porous concrete is 10.35m; The sleeve pipe of rubble/sand is squeezed in soil to predetermined projected depth 9m; Then in the sleeve pipe of rubble, settle the sleeve pipe of porous concrete under water, the casing length of porous concrete is also 10.35m.The diameter of rubble sleeve pipe is pile body diameter (0.5m), and inner sleeve is porous concrete stake core diameter (0.3m), drops into porous concrete until flush with sleeve pipe place suitable for reading at inner sleeve, and outer sleeve drops into rubble; Condiment is to the sleeve pipe place that flushes suitable for reading, and two sleeve pipes pull up simultaneously, and vibration limit, limit tube drawing goes out ground and pile; Pipe-pulling speed is 7m/min, and pile pipe is extracted behind ground, confirms that it meets after designing requirement stake top and lays the hardcore bed that a layer thickness is 300mm and bind, and next pile construction is carried out in telephone-moving.
In work progress, crane gear is steady, and leading truck is perpendicular to the ground, and vertical missing is for being greater than 0.8%, and pore-forming center is 30mm with design pile center deviation, and stake footpath Deviation Control is in 16mm, and the long deviation of stake is 34mm.Sequence of construction: the sequence of construction by two side direction centers is carried out, jumps and beats every stake every row.
After construction period and construction finish, check the construction note of stake, check sleeve pipe reciprocating extrusion vibration number and time, sleeve pipe heave amplitude and speed, the construction notes such as each amount of filler.
The detection of construction quality of pile body is by testing Bearing Capacity of Composite Foundation, and test result is 276.1KPa, and rubble loaded filter porous concrete pile composite foundation bearing capacity is apparently higher than Loar-boaring Capacity of Composite Gravel Foundation.
The preparation of porous concrete, composition material is: gather materials, cement, mineral admixture, water and thickener.In mass ratio, (cement and mineral admixture sum)/(gathering materials)=0.23; Water/(cement and mineral admixture sum)=0.28.Described mineral admixture is SILICA FUME and nano-calcium carbonate; Micro-wollastonite powder accounts for 5% of cement; Nano-calcium carbonate accounts for cement 0.5%, and thickener accounts for 3.5% of cementitious material (cement and micro-wollastonite powder and nano-calcium carbonate sum); The rubble that to gather materials for particle diameter be 5-20mm, the grating of gathering materials is shown in Fig. 4.
Porous concrete preparation technology is: take and gather materials by match ratio, cement, micro-wollastonite powder, nano-calcium carbonate, thickener, water, first by gathering materials, micro-wollastonite powder, nano-calcium carbonate, thickener and the total water amount mass ratio water mix and blend 1min that is 25%; Then the water of cement and total consumption 30% is joined and in mixture, stir 1min; The water that is finally 45% by total consumption mass ratio adds and in mixture, stirs 1min; After stirring, with tipping lorry, large particle diameter porous concrete being transported to composite foundation processing scene constructs.The time of building pile body is that concrete mixing adds water 0.5 hour that time timing starts.Field sampling is made test specimen, and sample dimensions is 15mm × 15mm × 15mm; Test specimen is carried out to maintenance in standard curing and water, and its transmission coefficient and compressive strength are tested in maintenance to 28 day.The experimental result of test is in table 1.
Embodiment 2
Certain project adopts rubble/sand loaded filter-porous concrete pile composite foundation to process.
A kind of rubble/sand loaded filter-porous concrete pile composite foundation, comprises pile body, and pile body outside is rubble/sand loaded filter, and rubble/sand loaded filter can stop that mud, to porous concrete stake infiltration, does not lose drainage simultaneously.Inside is porous concrete material, ensures permeable time to have certain strength and stiffness, is conducive to improve pipe-pulling speed, reduces the disturbance to stake week soil, improves the bearing capacity of composite foundation.Rubble/sand loaded filter is in conjunction with porous concrete material form compound foundation.
This ground treatment step is specific as follows:
Pile body adopts arranged in squares as shown in Figure 3, and according to mechanical execution condition, a stake footpath is 0.3m, and long according to geological conditions stake is 4m, 3 times of rubble/sand loaded filter-porous concrete stake diameter; Through overtesting, this arrangement meets bearing capacity of foundation soil and distortion meets the demands.Processing method is: determine according to site condition, bridges and culverts ground stabilization is reinforced for full hall, reinforces area and is greater than foundation bed area and increases by 3 campsheds in basic outer rim.Determine by field trial, the fullness coefficient of stake pore volume gets 1.2.Rubble/sand loaded filter filler is rubble, mud content 4%.The maximum particle of crushed stone 45mm.The hardcore bed that a layer thickness is 0.3m should be laid in stake top.
Specific construction technique is: in the position that pile body is set, will overlap effective leading truck and fix; The casing length of rubble and porous concrete is 4.6m; The sleeve pipe of rubble/sand is squeezed in soil to predetermined projected depth 4m; Then in the sleeve pipe of rubble, settle the sleeve pipe of porous concrete under water, the casing length of porous concrete is also 4.6m.The diameter of rubble sleeve pipe is pile body diameter, and inner sleeve is porous concrete stake core diameter, drops into porous concrete until flush with sleeve pipe place suitable for reading at inner sleeve, and outer sleeve drops into rubble; Condiment is to the sleeve pipe place that flushes suitable for reading, and two sleeve pipes pull up simultaneously, and vibration limit, limit tube drawing goes out ground and pile; Pipe-pulling speed is 7m/min, and pile pipe is extracted behind ground, confirms that it meets after designing requirement stake top and lays the hardcore bed that a layer thickness is 0.5m and bind, and next pile construction is carried out in telephone-moving.
In work progress, crane gear is steady, and leading truck is perpendicular to the ground, and vertical missing is for being greater than 0.8%, and pore-forming center is 30mm with design pile center deviation, and stake footpath Deviation Control is in 16mm, and the long deviation of stake is 34mm.Sequence of construction: the sequence of construction by two side direction centers is carried out, jumps and beats every stake every row.
After construction period and construction finish, check the construction note of stake, check sleeve pipe reciprocating extrusion vibration number and time, sleeve pipe heave amplitude and speed, the construction notes such as each amount of filler.
The detection of construction quality of pile body is by testing Bearing Capacity of Composite Foundation, and the bearing capacity value that records rubble loaded filter porous concrete pile composite foundation is 201.2.kpa; Rubble loaded filter porous concrete pile composite foundation bearing capacity is apparently higher than Loar-boaring Capacity of Composite Gravel Foundation.
The preparation of porous concrete, composition material is: gather materials, cement, mineral admixture, water and thickener.In mass ratio, (cement and mineral admixture sum)/(gathering materials)=0.21; Water/(cement and mineral admixture sum)=0.28.Described mineral admixture is SILICA FUME and nano-calcium carbonate; Micro-wollastonite powder accounts for 5% of cement; Nano-calcium carbonate accounts for cement 0.5%, and thickener accounts for 3.5% of cementitious material (cement and micro-wollastonite powder and nano-calcium carbonate sum); The rubble that to gather materials for particle diameter be 5-20mm, the grating of gathering materials is shown in Fig. 4.
Porous concrete preparation technology is: take and gather materials by match ratio, cement, micro-wollastonite powder, nano-calcium carbonate, thickener, water, first by gathering materials, micro-wollastonite powder, nano-calcium carbonate, thickener and the total water amount mass ratio water mix and blend 1min that is 25%; Then the water of cement and total consumption 30% is joined and in mixture, stir 1min; The water that is finally 45% by total consumption mass ratio adds and in mixture, stirs 1min; After stirring, with tipping lorry, large particle diameter porous concrete being transported to composite foundation processing scene constructs.The time of building pile body is that concrete mixing adds water 0.5 hour that time timing starts.Field sampling is made test specimen, and sample dimensions is 15mm × 15mm × 15mm; Test specimen is carried out to maintenance in standard curing and water, and its transmission coefficient and compressive strength are tested in maintenance to 28 day.The experimental result of test is in table 1.
Embodiment 3
Certain Project design adopts rubble/sand loaded filter-porous concrete pile composite foundation to process ground.
A kind of rubble/sand loaded filter-porous concrete pile composite foundation, comprises pile body, and pile body outside is rubble/sand loaded filter, and rubble/sand loaded filter can stop that mud, to porous concrete stake infiltration, does not lose drainage simultaneously.Inside is porous concrete material, ensures permeable time to have certain strength and stiffness, is conducive to improve pipe-pulling speed, reduces the disturbance to stake week soil, improves the bearing capacity of composite foundation.Rubble/sand loaded filter is in conjunction with porous concrete material form compound foundation.
This ground treatment step is specific as follows:
Pile body adopts arranged in squares as shown in Figure 3, and according to mechanical execution condition, a stake footpath is 0.8m, and long according to geological conditions stake is 30m, 5 times of rubble/sand loaded filter-porous concrete stake diameter; Through overtesting, this arrangement meets bearing capacity of foundation soil and distortion meets the demands.Processing method is: determine according to site condition, bridges and culverts ground stabilization is reinforced for full hall, reinforces area and is greater than foundation bed area and increases by 1 campshed in basic outer rim.Determine by field trial, the fullness coefficient of stake pore volume gets 1.4.Rubble/sand loaded filter filler is rubble, and mud content is less than 5%.The maximum particle of crushed stone is not more than 50mm.The hardcore bed that a layer thickness is 0.5m should be laid in stake top.
Specific construction technique is: in the position that pile body is set, will overlap effective leading truck and fix; The casing length of rubble and porous concrete is 34.5m; The sleeve pipe of rubble/sand is squeezed in soil to predetermined projected depth 30m; Then in the sleeve pipe of rubble, settle the sleeve pipe of porous concrete under water, the casing length of porous concrete is also 34.5m.The diameter of rubble sleeve pipe is pile body diameter, and inner sleeve is porous concrete stake core diameter, drops into porous concrete until flush with sleeve pipe place suitable for reading at inner sleeve, and outer sleeve drops into rubble; Condiment is to the sleeve pipe place that flushes suitable for reading, and two sleeve pipes pull up simultaneously, and vibration limit, limit tube drawing goes out ground and pile; Pipe-pulling speed is 10m/min, and pile pipe is extracted behind ground, confirms that it meets after designing requirement stake top and lays the hardcore bed that a layer thickness is 0.5 and bind, and next pile construction is carried out in telephone-moving.
In work progress, crane gear is steady, and leading truck is perpendicular to the ground, and vertical missing is for being greater than 0.8%, and pore-forming center is 30mm with design pile center deviation, and stake footpath Deviation Control is in 16mm, and the long deviation of stake is 34mm.Sequence of construction: the sequence of construction by two side direction centers is carried out, jumps and beats every stake every row.
After construction period and construction finish, check the construction note of stake, check sleeve pipe reciprocating extrusion vibration number and time, sleeve pipe heave amplitude and speed, the construction notes such as each amount of filler.
The detection of construction quality of pile body is by testing Bearing Capacity of Composite Foundation, and the porous concrete pile composite foundation bearing capacity value of test is 304.3kpa; Rubble loaded filter porous concrete pile composite foundation bearing capacity is apparently higher than Loar-boaring Capacity of Composite Gravel Foundation.
The preparation of porous concrete, composition material is: gather materials, cement, mineral admixture, water and thickener.In mass ratio, (cement and mineral admixture sum)/(gathering materials)=0.19; Water/(cement and mineral admixture sum)=0.28.Described mineral admixture is SILICA FUME and nano-calcium carbonate; Micro-wollastonite powder accounts for 5% of cement; Nano-calcium carbonate accounts for cement 0.5%, and thickener accounts for 3.5% of cementitious material (cement and micro-wollastonite powder and nano-calcium carbonate sum); The rubble that to gather materials for particle diameter be 5-20mm, the grating of gathering materials is shown in Fig. 4.
Porous concrete preparation technology is: take and gather materials by match ratio, cement, micro-wollastonite powder, nano-calcium carbonate, thickener, water, first by gathering materials, micro-wollastonite powder, nano-calcium carbonate, thickener and the total water amount mass ratio water mix and blend 1min that is 25%; Then the water of cement and total consumption 30% is joined and in mixture, stir 1min; The water that is finally 45% by total consumption mass ratio adds and in mixture, stirs 1min; After stirring, with tipping lorry, large particle diameter porous concrete being transported to composite foundation processing scene constructs.The time of building pile body is that concrete mixing adds water 0.5 hour that time timing starts.Field sampling is made test specimen, and sample dimensions is 15mm × 15mm × 15mm; Test specimen is carried out to maintenance in standard curing and water, and its transmission coefficient and compressive strength are tested in maintenance to 28 day.The experimental result of test is in table 1.
Table 1 porous concrete embodiment performance indications
By reference to the accompanying drawings the specific embodiment of the present invention is described although above-mentioned; but not limiting the scope of the invention; affiliated technical field technician should be understood that; on the basis of technical scheme of the present invention, those skilled in the art do not need to pay various amendments that creative work can make or distortion still in protection scope of the present invention.
Claims (8)
1. rubble/sand loaded filter-porous concrete pile composite foundation, it is characterized in that, comprise pile body, described pile body external structure is rubble/sand loaded filter, inside is porous concrete, stake footpath is 0.3～0.8m, outside rubble/sand the loaded filter of pile body thickness is 0.2～0.4m, pilespacing is doubly stake footpath of 3-5, porous concrete porosity > 20%, described porous concrete, comprise following raw material: gather materials, cement, mineral admixture, water and thickener, in mass ratio, cement and mineral admixture sum/gather materials=0.19～0.23, described mineral admixture is SILICA FUME and nano-calcium carbonate, micro-wollastonite powder accounts for 0%～10% of cement, nano-calcium carbonate accounts for cement 0～1%, thickener accounts for 2%～4.5% of cementitious material, the graded broken stone that to gather materials for particle diameter be 5-20mm, the mass ratio of water and cementitious material is 0.25～0.35.
2. rubble as claimed in claim 1/sand loaded filter-porous concrete pile composite foundation, is characterized in that, described pilespacing is to silt or sandy soil ground, and pilespacing is not more than 4.5 times an of footpath; Cohesive soil ground is not more than to 3 times an of footpath.
3. rubble as claimed in claim 1/sand loaded filter-porous concrete pile composite foundation, is characterized in that, described pile body adopts square, rectangle, triangle or radioactivity to arrange.
4. the processing method of the rubble/sand loaded filter-porous concrete pile composite foundation as described in claim 1-3 any one, is characterized in that, comprises the steps:
(1) determine stake footpath and pilespacing according to foundation settlement and requirement for bearing capacity, the thickness of amount of filler, stake top granular materials or damp clay in ground stabilization scope, reinforcement depth, pile body arrangement, stake hole;
(2) parameter obtaining according to step 1), in the position that pile body is set, to overlap effective leading truck fixes, the casing length of rubble/sand and porous concrete is 1.15 times of designing pile length, the sleeve pipe of rubble/sand is squeezed in soil to predetermined reinforcement depth, then in the sleeve pipe of rubble/sand, settle the sleeve pipe of porous concrete under water, the diameter of the sleeve pipe of rubble/sand is pile body diameter, inner sleeve is porous concrete stake core diameter, drop into porous concrete until flush with sleeve pipe place suitable for reading at inner sleeve, outer sleeve drops into rubble/sand, condiment is to the sleeve pipe place that flushes suitable for reading, two sleeve pipes pull up simultaneously, vibration limit, limit tube drawing plays ground and pile, pipe-pulling speed is 3～10m/min, pile pipe is extracted behind ground, confirm to bind with granular materials or damp clay after its composite design requires, next pile construction is carried out in telephone-moving.
5. processing method as claimed in claim 4, is characterized in that, in described step 1), definite method of the reinforcing scope of ground is as follows: reinforcing scope is greater than foundation bed area and is no less than 1～3 campshed in basic outer rim increase;
Pile body method for arranging is as follows: processing area ﹥ 1000m
2time, pile body adopts equilateral triangle layout, and for single footing or strip foundation, stake position adopts square, and rectangle, or isosceles triangle layout, for circular foundation or ring foundation, adopt radioactivity to arrange;
Definite method of reinforcement depth is as follows:
In the time of the buried depth ﹤ of soil supporting layer 10m, the buried depth that reinforcement depth is bearing stratum, bearing stratum is squeezed in pile body bottom; In the time of soil supporting layer buried depth >=10m, for the engineering of Deformation control, reinforcement depth meets composite foundation and is out of shape the requirement that is no more than structure foundation allowable strain, and for the engineering of pressing stability control, reinforcement depth is greater than the degree of depth of most dangerous slip surface face; In Liquefaction Foundation, reinforcement depth should adopt by the pertinent regulations of existing national standard " seismic design provision in building code " GB50011-2010, and stake is long can not be less than 4m, and is no more than 30m;
Stake footpath determines that method is as follows: while adopting immersed tunnelling method pile, diameter is 0.3～0.8m, and the diameter of saturated cohesive soil ground is 0.5～0.8m;
Determining of pilespacing is as follows: to silt or sandy soil ground, pilespacing is not more than 4.5 times an of footpath; Cohesive soil ground is not more than to 3 times an of footpath;
Filler method for determination of amount in stake hole: the amount of filler in stake hole is that a stake pore volume is multiplied by fullness coefficient, and fullness coefficient gets 1.2～1.4;
The thickness of rubble/sand loaded filter porous concrete stake top granular materials or damp clay is 0.3～0.5m.
6. processing method as claimed in claim 4, is characterized in that, described step 2) when construction, sand foundation carries out in the middle of peripheral or two side direction, and cohesive soil ground is from centre to the periphery or every applying work.
7. processing method as claimed in claim 4, is characterized in that, described step 2) leading truck is perpendicular to the ground, and vertical missing≤1.5%, pile position and design attitude deviation≤0.05m, stake footpath deviation≤0.02m, the long deviation≤0.1m of stake.
8. processing method as claimed in claim 4, is characterized in that, the preparation method of described porous concrete, comprises the steps:
1) weigh each batching;
2) stir: first by gathering materials, micro-wollastonite powder, nano-calcium carbonate, thickener and the total water amount mass ratio water mix and blend 1min that is 25%; Then the water of cement and total consumption 30% is joined and in mixture, stir 1min; The water that is finally 45% by total consumption mass ratio adds and in mixture, stirs 1min;
3) after stirring, get final product discharging, transport, is used.
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| CN103938609B (en) | 2015-12-02 |
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