Tear down and build the strengthening of foundation construction technology of house foundation
Technical field
The present invention relates to a kind of building strengthening structure, more particularly to a kind of strengthening of foundation construction skill for tearing down and building house foundation
Art.
Background technology
With the development of urban construction, some dilapidated houses need to be transformed, and original usual number of plies of dilapidated house is relatively low, pass
The load for passing ground is smaller, so the bearing capacity after basement process is relatively low.And the number of plies in house may compare after being transformed
Original dilapidated house wants much higher, and the load for passing to ground also can be larger, and ground must be handled again could meet bearing capacity
It is required that.Since the pile foundation in house after the pile foundation of original dilapidated house and transformation has larger difference, if dealt with improperly when appearance
It is uneven to easily cause local foundation deformation, causes differential settlement.
Invention content
For the deficiencies in the prior art, the purpose of the present invention is to provide a kind of bases for tearing down and building house foundation to add
Gu construction technology ensures that building settlement and load-carrying properties reach requirement.
There are two types of forms for the basement process of dilapidated house:First, being reinforced using rigid pile such as concrete-pile, basic type
Formula is usually cushion cap foundation;Second is that being reinforced using flexible pile such as cement mixing pile, foundation pattern is usually raft foundation.This
Invention uses different technical solutions for different pile foundation forms.
For the basis reinforced using rigid pile such as concrete-pile, using following technical scheme:
In order to promote economic benefit, existing pile foundation and concrete foundation are utilized as far as possible.Since cushion cap height is relatively high,
After foundation structure form is transformed into raft foundation, if raft foundation height is identical as cushion cap height, it will seem more wasteful,
Cushion cap can suitably be cut low.It is 600~800mm, raft plate that the basis in house, which uses raft foundation, raft foundation thickness, after transformation
Basis is constituted by cutting low rear cushion cap and new casting foundation, and new casting foundation lower rebar uses the reinforcing bar of a diameter of 20~25mm, reinforcing bar
Spacing is that 150~200mm, cushion cap and new casting foundation are linked to be entirety by dowel, and dowel spacing is 200~250mm, connection
A diameter of 22~the 25mm of muscle, dowel stretch into the pre-buried hole length of cushion cap be 250~300mm, cushion cap embedded hole a diameter of 24~
27mm, between dowel and cushion cap embedded hole gap using epoxy resin clog, dowel expose to cushion cap length be 400~
450mm.Back pouring hole is set in cushion cap, and back pouring hole diameter is identical as concrete-pile.
Original concrete-pile is usually arranged in the form of cushion cap, and minor diameter concrete-pile is arranged except cushion cap, small
Rubber block is arranged in concrete-pile stake top in a diameter of 150~300mm of diameter concrete-pile, and rubber block thickness is 100~150mm.
Precast concrete pipe collar is arranged in minor diameter concrete-pile pile crown, and precast concrete pipe collar is embedded in minor diameter concrete-pile pile crown height
For 100mm, precast concrete pipe collar top is higher by 120~150mm than minor diameter concrete-pile stake top.Minor diameter concrete-pile stake
Top is laid with rubble sand bedding course, and stone sand cushion thickness is 120~150mm, and minor diameter concrete-pile stake is long can be with concrete-pile
Stake is long identical, if Geological condition has a hard formation in superficial part, minor diameter concrete-pile can stretch into superficial part hard formation 500~
800mm forms length pilework with concrete-pile, and superficial part hard formation is generally 10~20m here, and the deep that concrete-pile stretches into is hard
Layer is generally the soil layer of 20m or more.
It is to enable minor diameter concrete-pile and soil preferably to cooperate with that rubble sand bedding course, which is arranged in minor diameter concrete-pile,
Effect, since the rigidity of minor diameter concrete-pile is very big, and native relatively small, the minor diameter concrete-pile stress under same strain
Can be larger, and soil stress can be smaller, minor diameter can effectively be reduced by being laid with rubble sand bedding course in minor diameter concrete-pile stake top
The rigidity of concrete-pile and surrounding soil ratio.There is horizontal comparison under upper load effect in rubble sand bedding course in order to prevent, overflows
Enter surrounding soil disequilibrium stress, in minor diameter concrete-pile stake top nesting precast concrete pipe collar.
Minor diameter concrete-pile quantity is according to requirement for bearing capacity and requirement of settlement control double control, minor diameter concrete-pile
Quantity first primarily determines that minor diameter concrete-pile quantity S is determined according to the following formula, S=m according to bearing capacity2Az/Ap2, AzFor raft plate base
Plinth bottom area, m2For minor diameter concrete-pile replacement rate, the i.e. ratio of stake total sectional area and raft foundation bottom area, Ap2For
Minor diameter concrete-pile sectional area, minor diameter concrete-pile replacement rate m2It determines according to the following formula, f=m1R1/Ap1+(Ec2/Ec1)
m2R2/Ap2+θ(Es/Ec1)fs, m in formula1For concrete-pile replacement rate, i.e. concrete-pile total sectional area and raft foundation bottom area
Ratio, R1For concrete-pile bearing capacity, Ap1For concrete-pile sectional area, Ec1For concrete-pile elasticity modulus, Ec2For minor diameter
Concrete-pile elasticity modulus, m2For minor diameter concrete-pile replacement rate, R2For minor diameter concrete-pile bearing capacity, Ap2For minor diameter
Concrete-pile sectional area, θ are reduction coefficient, take 0.5~0.6, EsFor native elasticity modulus, fsFor native foundation bearing capacity.
Sedimentation review is carried out after primarily determining minor diameter concrete-pile quantity according to requirement for bearing capacity.Settlement formula is adopted
With as follows:
P is the stress that top passes to ground, E in formulasiIt is composite modulus, ziAnd Zi-1
It is basic bottom surface respectively to the depth within the scope of i-th layer and (i-1)-th layer of bottom surface,WithFor basic bottom surface respectively to i-th layer and
Average additional stress coefficient within the scope of (i-1)-th layer of bottom surface, according to《Building foundation treatment technical specification》(JGJ-79-91) come true
Fixed, the composite modulus of entire ground can be divided into three parts along depth direction, and first part is concrete-pile, minor diameter concrete-pile
The ground formed with soil, second part are the ground that concrete-pile and soil are formed, and Part III is the ground that subjacent bed soil is formed.
First part composite modulus Es1Calculation formula is using as follows:Es1=m1Ec1+m2Ec2+(1-m1-m2)Es, second part
Composite modulus Es2Calculation formula is using as follows:Es2=m1Ec1+(1-m1)Es。
If sedimentation more than 100mm, increases minor diameter concrete-pile length and quantity carries out sedimentation review again, until
Until sedimentation reaches requirement.
Construction procedure includes:
(1) former cushion cap is cut higher than new casting foundation top mark high-order bit concrete, is cut to new casting foundation top mark height
150mm below position, and the extra reinforcing bar in top is cut off, lower part stirrup welds small stirrup, and small stirrup height is 100mm, small hoop
Bar diameter used by muscle is 8mm, and spacing is 50~100mm, and steel bar stress is set up above small stirrup and carries out banding fixed;
(2) former cushion cap concrete-pile position concrete chisel removal is gone out into back pouring hole, concrete-pile stake top carries out cutting low, concrete
Stake top absolute altitude is lower 100~150mm than former cushion cap bottom absolute altitude;Concrete-pile stake top reinforcing bar would generally stretch into former cushion cap 50cm, mix
Solidifying soil stake top is cut and is flushed as low as concrete-pile stake top behind position with cutting as low as wiping out concrete-pile stake top exposed steel bar behind position;
(3) the minor diameter concrete-pile between construction bearing platform, minor diameter concrete-pile stake top absolute altitude is than former cushion cap bottom absolute altitude
Low 50~100mm;
(4) it is inserted in precast concrete pipe collar in minor diameter concrete-pile stake top;
(5) it is laid with rubble sand bedding course in minor diameter concrete-pile stake top;
(6) it is drilled with preformed hole with electric drill, dowel is inserted into preformed hole, epoxy resin sealing preformed hole is used in combination and connect
Gap between muscle;
(7) new casting foundation reinforcing bar is bound, new casting foundation template is installed, pours new casting foundation concrete, it is then that cushion cap is low
In new casting foundation top mark high-order bit, concrete is poured;
(8) concrete-pile stake top is laid with rubber block after cutting as low as position;
(9) back pouring hole is closed with expansive concrete again after house reaches three layers;Since concrete-pile is in upper load
Effect is lower to be easy first to carry, and the especially native bearing capacity of minor diameter concrete-pile bearing capacity is difficult to be played, and back pouring hole waits for
Re-closed purpose is that minor diameter concrete-pile and soil is allowed first to participate in carrying after house reaches three layers, waits for that the number of plies increases concrete
The ability of stake, minor diameter concrete-pile and earth cooperation carrying can further enhance.
For the basis reinforced using flexible pile such as cement mixing pile, using following technical scheme:
It is 600~800mm that the basis in house, which uses raft foundation, raft foundation thickness, after transformation.It is held to promote ground
Power and non-deformability are carried, I-steel is inserted into part of cement mixing pile, I-steel length is the 1.8 of cement mixing pile length
~2.5 times.I-steel is arranged position and back pouring hole is arranged, and back pouring hole diameter is identical as cement mixing pile diameter.In order to avoid by
Stress concentration during power is laid with rubber block in I-steel, and rubber block thickness is 150~200mm.Back pouring hole after I-steel carrying
Punching resistance suffered by position can be larger, therefore reinforcing rib is arranged at back pouring hole position, and reinforcing rib is the steel of 4 a diameter of 25mm
Muscle, while the stirrup that spacing is 200mm, stirrup diameter 8mm are set.
I-steel quantity is according to requirement for bearing capacity and requirement of settlement control double control, and I-steel quantity is first according to bearing capacity
It primarily determines, I-steel quantity G is determined according to the following formula, G=m2gAz/Ap2g, AzFor raft foundation bottom area, m2gFor I-steel
Replacement rate, the i.e. ratio of stake total sectional area and raft foundation bottom area, Ap2gFor I-steel sectional area, I-steel replacement rate m2g
It determines according to the following formula,
F=m1sR1s/Ap1s+(Ec2g/Ec1s)m2gR2g/Ap2g+3(Es/Ec1s)fs, m in formula1sTo be not inserted into the cement of I-steel
Mixing pile replacement rate is not inserted into the ratio of the cement mixing pile total sectional area and raft foundation bottom area of I-steel, R1sFor
Bearing Capacity of Cement Deep Mixing Piles, Ap1sFor cement mixing dowel section area, Ec1sFor cement mixing pile elasticity modulus, Ec2gFor I-shaped steel bomb
Property modulus, m2gFor I-steel replacement rate, R2gFor I-steel bearing capacity, Ap2gFor I-steel sectional area, β is reduction coefficient, takes 0.7
~0.8, EsFor native elasticity modulus, fsFor native foundation bearing capacity.
Sedimentation review is carried out after primarily determining I-steel quantity according to requirement for bearing capacity.Settlement formula is using as follows:P is the stress that top passes to ground, E in formulasiIt is composite modulus, ziAnd zi-1Based on bottom
Face respectively to the depth within the scope of i-th layer and (i-1)-th layer of bottom surface,WithIt is basic bottom surface respectively to i-th layer and (i-1)-th layer
Average additional stress coefficient within the scope of bottom surface, according to《Building foundation treatment technical specification》(JGJ-79-91) it determines, entirely
The composite modulus of ground can be divided into three parts along depth direction, and first part is the ground that cement mixing pile, I-steel and soil are formed
Base, second part are the ground that I-steel and soil are formed, and Part III is the ground that subjacent bed soil is formed.
First part composite modulus Es1sCalculation formula is using as follows:Es1s=m1sEc1s+m2gEc2g+(1-m1s-m2g)Es, the
Two part composite modulus Es2sCalculation formula is using as follows:Es2s=m2gEc2g+(1-m2g)Es。
If sedimentation more than 100mm, increases I-steel length and quantity carries out sedimentation review again, until sedimentation reaches
Until it is required that.
Construction procedure includes:
(1) the raft board concrete for installing I-steel position is cut into out back pouring hole, and cuts off the extra reinforcing bar in top;
(2) drilling machine drilling tool passes through back pouring hole to be drilled with I-shaped slot in cement mixing stake body, and drill tip installs I-shaped cutter
Cut soil cement, I-steel sling using loop wheel machine, I-steel be inserted into during I-shaped slot ensured by fixing steel plate it is vertical
Degree;
(3) gap of waterglass closing I-steel and I-shaped slot, waterglass injection pressure are injected after I-steel is inserted into
For 1~1.2MPa, to ensure slip casting effect.
(4) rubber block is laid at the top of I-steel;
(5) steel reinforcement cage being made of reinforcing rib and stirrup is put into back pouring hole again after house reaches three layers;Due to work
Word steel rigidity is obviously more much greater than cement mixing pile rigidity or native rigidity, is easy first to carry under upper load effect, water
The especially native bearing capacity of mud stirring pile bearing capacity is difficult to be played, back pouring hole re-closed mesh after house reaches three layers
Be allow cement mixing pile and soil first participate in carrying, wait for the number of plies increase cement mixing pile, I-steel and earth cooperation carrying ability
It can further enhance.
(6) back pouring hole is poured, back pouring hole uses expansive concrete;Back pouring hole pours sequence to be intermediate behind first periphery, and to the greatest extent
Amount is relatively uniform when I-steel being made to carry using symmetrical closed mode.
Constructing operation of the present invention is convenient, securely and reliably.
Description of the drawings
Fig. 1 is cushion cap schematic diagram, and Fig. 2 is the raft foundation elevational schematic view with rigid pile foundation form, and Fig. 3 is band rigidity
The raft foundation floor map of pile foundation form, Fig. 4 are the raft foundation floor map with flexible pile base form.
1, cushion cap, 2, concrete-pile, 3, rubber block, 4, back pouring hole, 5, dowel, 6, minor diameter concrete-pile, 7, prefabricated
Concrete pipe collar, 8, rubble sand bedding course, 9, new casting foundation, 10, cement mixing pile, 11, I-steel.
Specific implementation mode
Embodiment one
It is 700mm that the basis in house, which uses raft foundation, raft foundation thickness, after transformation, and raft foundation is by cutting low rear cushion cap
1 and new casting foundation 9 constitute, 9 lower rebar of new casting foundation use a diameter of 22mm reinforcing bar, bar spacing 150mm, cushion cap 1
Entirety is linked to be by dowel 5 with new casting foundation 9,5 spacing of dowel is 200mm, 5 a diameter of 22mm of dowel, and dowel 5 is stretched
Enter 1 pre-buried hole length of cushion cap for 250mm, a diameter of 24mm of 1 embedded hole of cushion cap, gap is adopted between 1 embedded hole of dowel 5 and cushion cap
It is clogged with epoxy resin, it is 400mm that dowel 5, which exposes to 1 length of cushion cap,.Back pouring hole 4 is set in cushion cap 1,4 diameter of back pouring hole with
Concrete-pile 2 is identical.
Minor diameter concrete-pile 6,6 a diameter of 200mm of minor diameter concrete-pile, in concrete-pile 2 are arranged except cushion cap 1
Rubber block 3 is arranged in stake top, and 3 thickness of rubber block is 120mm.Precast concrete pipe collar 7 is arranged in 6 pile crown of minor diameter concrete-pile, in advance
It is 100mm that concrete pipe collar 7 processed, which is embedded in 6 pile crown height of minor diameter concrete-pile, and 7 top of precast concrete pipe collar is more mixed than minor diameter
Solidifying soil 6 stake top of stake is higher by 120mm.6 stake top of minor diameter concrete-pile is laid with rubble sand bedding course 8, and 8 thickness of rubble sand bedding course is
120mm, Geological condition have hard formation in 15m superficial parts, and minor diameter concrete-pile 6 stretches into superficial part hard formation 600mm, with concrete-pile
2 form length pilework.
6 quantity of minor diameter concrete-pile is according to requirement for bearing capacity and requirement of settlement control double control, minor diameter concrete
6 quantity of stake first primarily determine that 6 quantity S of minor diameter concrete-pile is determined according to the following formula, S=m according to bearing capacity2Az/Ap2, AzFor raft
Plate foundation bottom area, m2For 6 replacement rate of minor diameter concrete-pile, the i.e. ratio of stake total sectional area and raft foundation bottom area
Value, Ap2For 6 sectional area of minor diameter concrete-pile, 6 replacement rate m of minor diameter concrete-pile2It determines according to the following formula, f=m1R1/Ap1+
(Ec2/Ec1)m2R2/Ap2+θ(Es/Ec1)fs, m in formula1For 2 replacement rate of concrete-pile, i.e. 2 total sectional area of concrete-pile and raft plate base
The ratio of plinth bottom area, R1For 2 bearing capacity of concrete-pile, Ap1For 2 sectional area of concrete-pile, Ec1For 2 springform of concrete-pile
Amount, Ec2For 6 elasticity modulus of minor diameter concrete-pile, m2For 6 replacement rate of minor diameter concrete-pile, R2For minor diameter concrete-pile 6
Bearing capacity, Ap2For 6 sectional area of minor diameter concrete-pile, θ is reduction coefficient, takes 0.5~0.6, EsFor native elasticity modulus, fsFor soil
Foundation bearing capacity.
Sedimentation review is carried out after primarily determining 6 quantity of minor diameter concrete-pile according to requirement for bearing capacity.Settlement formula
Using as follows:
P is the stress that top passes to ground, E in formulasiIt is composite modulus, ziAnd Zi-1
It is basic bottom surface respectively to the depth within the scope of i-th layer and (i-1)-th layer of bottom surface,WithFor basic bottom surface respectively to i-th layer and
Average additional stress coefficient within the scope of (i-1)-th layer of bottom surface, according to《Building foundation treatment technical specification》(JGJ-79-91) come true
Fixed, the composite modulus of entire ground can be divided into three parts along depth direction, and first part is concrete-pile 2, minor diameter concrete
The ground that stake 6 and soil are formed, second part are the ground that concrete-pile 2 and soil are formed, and Part III is what subjacent bed soil was formed
Ground.
First part composite modulus Es1Calculation formula is using as follows:Es1=m1Ec1+m2Ec2+(1-m1-m2)Es, second part
Composite modulus Es2Calculation formula is using as follows:Es2=m1Ec1+(1-m1)Es。
If sedimentation more than 100mm, increases by 6 length of minor diameter concrete-pile and quantity carries out sedimentation review again, directly
Until sedimentation reaches requirement.According to above-mentioned steps, 11 quantity of I-steel is determined as 125.
Construction procedure includes:
(1) former cushion cap 1 is cut higher than 9 top mark high-order bit concrete of new casting foundation, is cut to 9 top mark of new casting foundation
150mm below high-order bit, and the extra reinforcing bar in top is cut off, lower part stirrup welds small stirrup, and small stirrup height is 100mm, small
Bar diameter used by stirrup is 8mm, and spacing is 50~100mm, and steel bar stress is set up above small stirrup and bind solid
It is fixed;
(2) 1 concrete-pile of former cushion cap, 2 position concrete chisel removal is gone out into back pouring hole 4,2 stake top of concrete-pile cut low, mixes
Solidifying soil 2 stake top absolute altitude of stake is lower 100~150mm than 1 bottom absolute altitude of former cushion cap;2 stake top of concrete-pile cut as low as behind position by concrete-pile 2
Stake top exposed steel bar is wiped out and is flushed as low as 2 stake top of concrete-pile behind position with cutting;
(3) the minor diameter concrete-pile 6 between construction bearing platform 1,6 stake top absolute altitude of minor diameter concrete-pile is than 1 bottom of former cushion cap
Low 50~the 100mm of absolute altitude;
(4) it is inserted in precast concrete pipe collar 7 in 6 stake top of minor diameter concrete-pile;
(5) it is laid with rubble sand bedding course 8 in 6 stake top of minor diameter concrete-pile;
(6) it is drilled with preformed hole with electric drill, dowel 5 is inserted into preformed hole, epoxy resin sealing preformed hole and company is used in combination
Connect gap between muscle 5;
(7) new 9 reinforcing bar of casting foundation is bound, 9 template of new casting foundation is installed, 9 concrete of new casting foundation is poured, then by cushion cap
1 is poured less than 9 top mark high-order bit concrete of new casting foundation;
(8) 2 stake top of concrete-pile is laid with rubber block 3 after cutting as low as position;
(9) back pouring hole 4 is closed with expansive concrete again after house reaches three layers.
Embodiment two
For using the flexible pile basis that for example cement mixing pile 10 is reinforced in the present embodiment, using following technical side
Case:
It is 700mm that the basis in house, which uses raft foundation, raft foundation thickness, after transformation, and 10 length of cement mixing pile is
15m, is inserted into I-steel 11 in part of cement mixing pile 10, and 11 length of I-steel is 30m.Position raft plate base is arranged in I-steel 11
Back pouring hole 4 is arranged in plinth, and 4 diameter of back pouring hole is identical as 10 diameter of cement mixing pile.It is laid with rubber block 3, rubber block 3 in I-steel 11
Thickness is 180mm.Reinforcing rib is set at 4 position of back pouring hole, reinforcing rib is the reinforcing bar of 4 a diameter of 25mm, while spacing is arranged
For the stirrup of 200mm, stirrup diameter 8mm.
11 quantity of I-steel is according to requirement for bearing capacity and requirement of settlement control double control, and 11 quantity of I-steel first hold by basis
It carries power and primarily determines that 11 quantity G of I-steel is determined according to the following formula, G=m2gAz/Ap2g, AzFor raft foundation bottom area, m2gFor
11 replacement rate of I-steel, the i.e. ratio of stake total sectional area and raft foundation bottom area, Ap2gFor 11 sectional area of I-steel, I-shaped
11 replacement rate m of steel2gIt determines according to the following formula,
F=m1sR1s/Ap1s+(Ec2g/Ec1s)m2gR2g/Ap2g+β(Es/Ec1s)fs, m in formula1sTo be not inserted into the water of I-steel 11
10 replacement rate of mud mixing pile is not inserted into 10 total sectional area of cement mixing pile of I-steel 11 and the ratio of raft foundation bottom area
Value, R1sFor 10 bearing capacity of cement mixing pile, Ap1sFor 10 sectional area of cement mixing pile, Ec1sFor 10 elasticity modulus of cement mixing pile,
Ec2gFor 11 elasticity modulus of I-steel, m2gFor 11 replacement rate of I-steel, R2gFor 11 bearing capacity of I-steel, Ap2gIt is cut for I-steel 11
Area, β are reduction coefficient, take 0.75, EsFor native elasticity modulus, fsFor native foundation bearing capacity;
Sedimentation review is carried out after primarily determining 11 quantity of I-steel according to requirement for bearing capacity.Settlement formula is using such as
Under:P is the stress that top passes to ground, E in formulasiIt is composite modulus, ziAnd Zi-1Based on
Bottom surface respectively to the depth within the scope of i-th layer and (i-1)-th layer of bottom surface,WithIt is basic bottom surface respectively to i-th layer and (i-1)-th
Average additional stress coefficient within the scope of layer bottom surface, according to《Building foundation treatment technical specification》(JGJ-79-91) it determines, it is whole
The composite modulus of a ground can be divided into three parts along depth direction, and first part is cement mixing pile 10, I-steel 11 and native shape
At ground, second part be I-steel 11 and soil formed ground, Part III be subjacent bed soil formed ground.First
Divide composite modulus Es1sCalculation formula is using as follows:Es1s=m1sEc1s+m2gEc2g+(1-m1s-m2g)Es, second part composite modulus
Es2sCalculation formula is using as follows:Es2s=m2gEc2g+(1-m2g)Es。
If sedimentation more than 100mm, increases by 11 length of I-steel and quantity carries out sedimentation review again, until sedimentation reaches
Until requirement.According to above-mentioned steps, 11 quantity of I-steel is determined as 76.
Construction procedure includes:
(1) the raft board concrete for installing 11 position of I-steel is cut into out back pouring hole 4, and cuts off the extra reinforcing bar in top;
(2) drilling machine drilling tool passes through back pouring hole 4 to be drilled with I-shaped slot in 10 pile body of cement mixing pile, and drill tip installs I-shaped knife
Have to cut soil cement, I-steel 11 is sling using loop wheel machine, I-steel 11 is protected during being inserted into I-shaped slot by fixing steel plate
Demonstrate,prove verticality;
(3) gap of waterglass closing I-steel 11 and I-shaped slot, waterglass injection are injected after I-steel 11 is inserted into
Pressure is 1~1.2MPa, to ensure slip casting effect.
(4) it is laid with rubber block 3 at 11 top of I-steel;
(5) steel reinforcement cage being made of reinforcing rib and stirrup is put into back pouring hole 4 again after house reaches three layers;
(6) back pouring hole 4 is poured, back pouring hole 4 uses expansive concrete;Back pouring hole 4 pours sequence to be intermediate behind first periphery, and
Symmetrical closed mode is used as possible.