CN110206038A - Supporting construction and construction method at a kind of concave foundation pit external corner - Google Patents
Supporting construction and construction method at a kind of concave foundation pit external corner Download PDFInfo
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- 238000010276 construction Methods 0.000 title claims abstract description 93
- 230000008093 supporting effect Effects 0.000 title claims abstract description 82
- 239000002689 soil Substances 0.000 claims abstract description 73
- 238000000034 method Methods 0.000 claims abstract description 23
- 239000000203 mixture Substances 0.000 claims abstract description 4
- 238000009412 basement excavation Methods 0.000 claims description 48
- 238000011065 in-situ storage Methods 0.000 claims description 17
- 230000008878 coupling Effects 0.000 claims description 10
- 238000010168 coupling process Methods 0.000 claims description 10
- 238000005859 coupling reaction Methods 0.000 claims description 10
- 230000000903 blocking effect Effects 0.000 claims description 8
- 238000004364 calculation method Methods 0.000 claims description 7
- 229910000831 Steel Inorganic materials 0.000 claims description 5
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- 239000004570 mortar (masonry) Substances 0.000 description 2
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Classifications
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D17/00—Excavations; Bordering of excavations; Making embankments
- E02D17/02—Foundation pits
- E02D17/04—Bordering surfacing or stiffening the sides of foundation pits
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/22—Piles
- E02D5/34—Concrete or concrete-like piles cast in position ; Apparatus for making same
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/74—Means for anchoring structural elements or bulkheads
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Abstract
The present invention provides a kind of supporting construction and construction method at concave foundation pit external corner.Institute's supporting construction includes three branch mask compositions, it is parallel to the support system that first mask in foundation pit sideline is made of Single row pillars and multiple rows of prestress anchorage cable, second mask and third branch mask perpendicular to foundation pit sideline use Double-row Piles Support system, using " calculating inquiry of finite soil soil pressure " and " close to existing building foundation pit finite soil earth pressure computation method ", the mentioned method calculating finite width soil body acts on reduction coefficient of the active earth pressure on Double-row-piles Structure relative to Rankine Earth Pressure to the construction parameter of double-row pile, then plane rod piece elastic support method is used, according to " building foundation pit supporting technical regulation ", it is calculated in conjunction with positive deep basal pit software is managed.The force-mechanism that the present invention can not only improve supporting construction avoids Multi anchorage effect, effective to limit foundation pit displacement, can also shorten the construction period, reduce support pile and anchor cable length, reduce project cost.
Description
Technical field
The present invention relates to foundation pit supporting project fields, and in particular to a kind of supporting construction at concave foundation pit external corner and
Construction method.
Technical background
Demand based on Management in Real Estate Exploration, developer usually can preferentially build in sale before building the commercial house
The heart, due to the particular attribute of marketing center, its position generally can be close to foundation pit side, and causing, which will form in excavation of foundation pit, has
The concave foundation pit of multiple external corners.In deep foundation pit support field, foundation pit external corner is to pay close attention to object, can be in Foundation Pit Support Design side
Emphasis considers the limitation being displaced to it in case.
In the design of Supporting System of Deep Excavations, China generallys use board-like support system, self-supporting retaining design at present
And the support systems such as slope excavation.Campshed+cable bolting structure has the construction for facilitating earth excavation and underground structure, engineering suitable
It is support system very widely used at present with the advantages that property is strong, project cost is low, construction technology is mature.However in foundation pit
It at external corner, will appear the Multi anchorage effect of anchor cable intersection using campshed+cable bolting scheme merely, lead to constructional difficulties, supporting effect
Phenomena such as fruit reduces, the soil body is easily destroyed, and then the ground other than construction stream line supporting range can be caused crack or position occur
The phenomenon that shifting.
In the soil pressure distribution of supporting scheme, Rankine's earth pressure theory can be usually used.The vacation of Rankine's earth pressure theory
If condition first is that semi-infinite half-space model, and supporting and be unsatisfactory for this it is assumed that recessed at the mentioned concave foundation pit external corner of the present invention
The soil pressure of the type foundation pit external corner two sides supporting construction receiving finite width soil body, it is therefore desirable to the soil pressure of the finite width soil body
It is modified.
Summary of the invention
The present invention provides a kind of for concave foundation pit sun according to the insufficient situation of the existing single supporting scheme of concave foundation pit
Supporting construction and construction method at angle, this method are directed to concave foundation pit, propose double-row pile and+three row's prestressed anchor of Single row pillars
The supporting scheme of rope supporting construction combination, and double-row pile scheme is optimized and revised according to modified finite width soil body soil pressure；This
The force-mechanism that supporting construction can not only be improved by inventing mentioned supporting structure system avoids Multi anchorage effect, effectively limits foundation pit
Displacement can also reduce anchor cable length, save raw material usage.
Technical solution provided by the invention: the supporting construction at a kind of concave foundation pit external corner, including along foundation pit side
Two external corner portions that line is recessed, described two external corner portions are made of three branch masks, and three branch masks and foundation pit sideline
It encloses and sets to form concave foundation pit, it is characterised in that: first mask for being parallel to foundation pit sideline is by Single row pillars and multiple rows of prestressing force
The support system of anchor cable composition, Single row pillars are equally spaced along the sideline of first mask, and multiple rows of prestress anchorage cable is along foundation pit
Inner wall is obliquely squeezed into the soil layer other than foundation pit from the top down, and stake top of the first row prestress anchorage cable apart from Single row pillars
1.5~2.5m；Second mask and third branch mask perpendicular to foundation pit sideline use Double-row Piles Support system, the stake of every campshed
Spacing is not more than twice diameter.
The present invention preferably technical solution: enclosing construction within the region set in three branch masks has building, the concave
The foundation depth of foundation pit is not less than the half of building center width.
The present invention preferably technical solution: the Double-row Piles Support system of second mask and third branch mask includes two
Arrange cast-in-situ bored pile arranged side by side, the stake top of every cast-in-situ bored pile is equipped with bored concrete pile crown beam, the crown beams of two rows of cast-in-situ bored piles it
Between connected by coupling beam between stake.
The present invention preferably technical solution: the prestress anchorage cable is equipped with three rows, and the vertical interval between three rows is 2.5
~3.5m, horizontal space are twice of pilespacing, and anchor cable incident angle is 20~30 °.
The construction method of supporting construction at a kind of concave foundation pit external corner provided by the invention, for the indent of concave foundation pit
Region is constructed, and recessed area includes three branch masks, and three branch masks form two external corner portions, it is characterised in that tool
Steps are as follows for body:
(1) according to geology prospecting report, surrounding enviroment condition, excavation of foundation pit depth, the supporting at foundation pit indent position is determined
Scheme is parallel to the branch mask in foundation pit sideline using Retaining Structure with Double-row Piles, uses list perpendicular to two masks in foundation pit sideline
Campshed adds three row's prestressing anchor support structures；
(2) Rankine's earth pressure theory and plane rod piece elastic support method are used, according to " building foundation pit supporting technical regulation ",
Calculate the construction parameter of Single row pillars in conjunction with positive deep basal pit software is managed, and determines the construction parameter of three row's prestress anchorage cables；
(3) using " calculating inquiry of finite soil soil pressure " and " close to existing building foundation pit finite soil active soil pressure
Power calculation method " mentioned method calculates the finite width soil body and acts on the active earth pressure on Double-row-piles Structure relative to Rankine soil
Then the reduction coefficient of pressure uses plane rod piece elastic support method, according to " building foundation pit supporting technical regulation " (JGJ 120-
2012) the 4th chapter provides, is calculated in conjunction with positive deep basal pit software is managed, determines the parameter of support pile in Double-row-piles Structure；Wherein institute
It is as follows to state finite width soil body active earth pressure reduction coefficient calculation formula:
In formula: B --- finite soil calculates width (m)；
H --- excavation of foundation pit depth (m)；
--- finite width soil body active earth pressure upper limit value (kPa)；
Pa--- the total active earth pressure of Rankine (kPa)；
εa--- finite width soil body soil pressure reduction coefficient；
z0--- active earth pressure zero point depth (m) after soil blocking component；
Ka--- Rankine Active Earth Pressure coefficient；
Kp--- Rankine coefficient of passive earth pressure；
The cohesive strength (kPa) of soil other than c --- soil blocking component；
--- the internal friction angle (°) of soil other than soil blocking component；
(4) after every construction parameter determines, start the construction for carrying out supporting construction, three branch masks of constructing first
Support pile pile body constructs two rows of cast-in-situ bored piles respectively perpendicular to two branch masks in foundation pit sideline, is parallel to foundation pit sideline
One gang drill hole pouring pile of supporting surface construction, the excavation pit construction stake apical cap beam after support pile pile body reaches curing period, it is desirable that base
It cheats excavation width and is not less than 10m, excavation of foundation pit absolute altitude is identical as hat bottom elevation, and the Single row pillars and double-row pile of three branch masks
Crown beam one-piece casting；
(5) after reaching crown beam curing period, layer and section excavation pit, and in the first supporting identity distance for being parallel to foundation pit sideline
Position construction first row anchor cable and waist rail from single 1.5~2.5m of stake top；
(6) after completing the locking of first row anchorage cable stretching, continue layer and section excavation pit, and hang down apart from first row anchor cable
The position construction second row anchor cable of 2.5~3.5m of straight distance, excavation of foundation pit width are not less than 10m, excavation of foundation pit absolute altitude and second
It is identical to arrange waist bottom elevation；
(7) after completing the locking of second row anchorage cable stretching, continue layer and section excavation pit, and hang down apart from second row anchor cable
The position construction third of 2.5~3.5m of straight distance arranges prestress anchorage cable, and excavation of foundation pit width is not less than 10m, excavation of foundation pit absolute altitude
It is identical as third row's waist bottom elevation；
(8) it completes third and arranges prestress anchorage cable tensioning fixation, earth excavation is to foundation pit bottom absolute altitude, both perpendicular to foundation pit side
The earthwork of supporting side, which is also excavated, arrives foundation pit bottom absolute altitude.
The present invention preferably technical solution: the stake of the Single row pillars calculated in the step (2) is long deep not less than excavation of foundation pit
2 times of degree, diameter are 0.6~1.0m, and stake spacing is 1.0~1.4m, and is no more than 2 times of stake diameter；Stake top crown beam width ratio
The stake big 200mm of diameter, is highly 0.6~0.8m.
The present invention preferably technical solution: the freedom length of every row's prestress anchorage cable is not less than in the step (2)
5.0m across soft stratum and is anchored in the soil layer that foundation bearing capacity is more than 100kPa；Anchor cable horizontal spacing is the 2 of stake spacing
Times, first row anchor cable is 2.5~3.5m away from 1.5~2.5m of ground, the vertical interval of remaining anchor cable；Three row's prestress anchorage cables enter
Firing angle is consistent, is 20 °~30 °；The lock value of prestress anchorage cable is 160~240kN.
The present invention preferably technical solution: the construction of every row's anchor cable successively includes cable body in the step (5)~step (7)
Preparation, drilling, cable body decentralization, twice mortar depositing construction carry out waist rail steel after rope infuses installation and slip casting is completed on the inside of foundation pit
The construction of waist rail is completed in muscle binding, formwork and concreting, finally carries out anchorage cable stretching locking construction, the anchor of each supporting section
Suo Lianxu construction, crown beam and waist rail one-piece casting.
The present invention preferably technical solution: before waist rail pours in step (5)~(7), using pvc pipe by tensioning section anchor cable
It is separated with waist rail concrete, and pvc pipe penetrates through waist rail section, local damage phenomenon does not occur.
Support pile of the invention is cast-in-situ bored pile, and anchor cable is prepared by steel strand wires.
The present invention successively uses Rankine's earth pressure theory and plane rod piece elastic support method, the plane rod piece elastic support
Method assumes that soil-baffling structure is plane strain problems, takes the retaining wall of unit width as the beam on elastic foundation vertically placed, support
It is reduced to spring fastening with anchor pole, the following soil body of excavation face is simulated using spring in foundation pit, on the outside of soil-baffling structure known to effect
Water pressure and soil pressure.It is provided according to " building foundation pit supporting technical regulation " (JGJ 120-2012) the 4th chapter, in conjunction with the positive deep base of reason
Hole software is calculated, and calculates that the stake diameter of+three row's prestressing anchor support structure of Single row pillars, stake be long, stake spacing parameter, and is determined
The parameters such as arrangement of reinforcement, the stake top crown beam of+three row's prestress anchorage cable of Single row pillars；Retaining Structure with Double-row Piles in the present invention uses double brill
Coupling beam structure type between hole pouring pile+stake top crown beam+stake, using " calculating inquiry of finite soil soil pressure " and " close to existing
Building foundation pit finite soil earth pressure computation method " theoretical and plane rod piece elastic support method is mentioned, calculate finite soil
Reduction coefficient of the active earth pressure on Double-row-piles Structure relative to Rankine Active Earth Pressure is acted on, according to " building foundation pit branch
Protect technical regulation " (JGJ 120-2012) the 4th chapter regulation, it is calculated in conjunction with positive deep basal pit software is managed, and then determine double-row pile
In structure support pile and the parameters such as stake diameter, length, arrangement of reinforcement, stake spacing and coupling beam size.
The present invention is directed to concave foundation pit, proposes what double-row pile was combined with+three row's prestressing anchor support structure of Single row pillars
Supporting scheme, and according to modified finite width soil body soil pressure reduction coefficient, double-row pile scheme is optimized and revised, the present invention is mentioned
The force-mechanism that supporting structure system can not only improve supporting construction avoids Multi anchorage effect, effective to limit foundation pit displacement, also
Support pile and anchor cable length can be reduced, save raw material usage, great application value.
Detailed description of the invention
Fig. 1 is the supporting construction plan view of the embodiment of the present invention；
Fig. 2 is finite width soil body earth pressure computation illustraton of model of the present invention；
Fig. 3 is plane rod piece elastic support method calculation diagram of the present invention；
Fig. 4 is concave foundation pit Retaining Structure with Double-row Piles reference section of the embodiment of the present invention；
Fig. 5 is+three row's prestress anchorage cable Structure Calculation section of Single row pillars of the embodiment of the present invention；
Fig. 6 is concave foundation pit of the embodiment of the present invention using the mentioned method calculated result of this patent；
Fig. 7 is+three row's prestress anchorage cable section calculated result of concave foundation pit of embodiment of the present invention Single row pillars.
In figure: 1-the second mask, 1-1-cast-in-situ bored pile, 2-third branch masks, 3-the first mask, 3-1-
Single row pillars, 3-2-prestress anchorage cable, 3-3-Single row pillars crown beam, 3-4-waist rail, 4-buildings, 4-1-building bottom stake
Raft foundation, 5-concave foundation pits, 6-bored concrete pile crown beams, coupling beam between 7-stakes.
Specific embodiment
The present invention will be further described with reference to the accompanying drawings and examples.
Supporting construction at a kind of concave foundation pit external corner provided by the invention includes along foundation pit sideline 5-1 as shown in Figure 1
Two external corner portions being recessed, described two external corner portions are made of three branch masks, and three branch masks and foundation pit sideline 5-1
It encloses and sets to form concave foundation pit 5, as shown in figure 5, first mask 3 for being parallel to foundation pit sideline 5-1 is by Single row pillars 3-1 and three rows
The support system of prestress anchorage cable 3-2 composition, Single row pillars 3-1 are equally spaced along the sideline of first mask 3, three row's prestressing force
Anchor cable 3-2 is obliquely squeezed into the soil layer other than foundation pit from the top down along foundation pit inner wall, and first row prestress anchorage cable 3-2
1.5~2.5m of stake top apart from Single row pillars 3-1, the vertical interval between three rows is 2.5~3.5m, and horizontal space is pilespacing
Twice, anchor cable incident angle is 20~30 °.As shown in figure 4, perpendicular to second mask 1 and third of foundation pit sideline 5-1
Branch mask 2 uses Double-row Piles Support system, and the stake spacing of every campshed is not more than twice diameter；The Double-row Piles Support system includes
The stake top of two rows of cast-in-situ bored pile 1-1 arranged side by side, every cast-in-situ bored pile are equipped with bored concrete pile crown beam 6, two rows of cast-in-situ bored piles
It is connected between crown beam by coupling beam 7 between stake.
Construction method below with reference to embodiment for above-mentioned supporting construction further illustrates that embodiment is directed to a certain engineering
Concave foundation pit is embodied, project profile: place is located at Kunming Guandu District, and projects awaiting construction plan total land area
54724.97 ㎡, foundation pit vertical cut line Zhou Changyue 995m are equipped with two layers of basement, 7.45~10.50m of excavation of foundation pit depth.
Concave Foundation Pit top is by synchronous construction marketing center, and having a size of 18m × 30m, excavation of foundation pit depth is 10.5m, root for marketing center
It is reported according to geologic prospect, the detailed geological conditions information in the foundation pit region in table 1 can be obtained:
Table 1 is the detailed geologic condition of the construction area
Marketing center uses pile-raft foundation in embodiment, and pile foundation buried depth is more than hole bottom cutting depth, and the foundation pit is deep
Degree is not less than the half of marketing center's width, which is level-one.For pattern foundation pit supporting structure, the project leader
Propose four kinds of supporting schemes: (1) single+three row's prestress anchorage cable of cast-in-situ bored pile+stake top crown beam scheme；(2) double drilling
Coupling beam scheme between bored concrete pile+stake end crown beam+stake；(3) slope+single cast-in-situ bored pile+prestress anchorage cable scheme；(4) two-stage is put
Slope+grouting tube scheme.
If three branch masks are all made of anchored pile supporting, it will appear the Multi anchorage effect generated because anchor cable intersects,
Cause foundation pit larger displacement；If concave foundation pit individually uses the scheme of double-row pile, construction cost is higher.Therefore it needs to supporting
Scheme carries out type selecting again.
It studies by analysis, using the technical solution in the present invention, in conjunction with supporting scheme (1) and supporting scheme (2),
Foundation pit side is parallel to using single+three row's prestress anchorage cable of cast-in-situ bored pile+stake top crown beam scheme；It is all made of perpendicular to foundation pit side
Coupling beam scheme between gang drill hole pouring pile+stake end crown beam+stake, wherein the soil pressure in supporting scheme (1) is managed using Rankine Earth Pressure
Plane rod piece elastic support method is referred to, it, can be in conjunction with managing that positive deep basal pit software carries out according to " building foundation pit supporting technical regulation "
Stake diameter 800mm, the long 30.5m of stake, stake spacing 1000mm, arrangement of reinforcement 10C32, the 800 × 800mm of stake top crown beam of Single row pillars is calculated
Etc. parameters, while can determine the absolute altitude (respectively apart from stake top 2.0m, 5.0m, 8.0m) of three row's prestress anchorage cables, cable body (
S15.2 steel strand wires), length (respectively 28.0m, 32.5m, 25.5m), 25 ° of incidence angle, lock value (respectively 180kPa,
220kPa,240kPa)；Its plane rod piece elastic support method assumes that soil-baffling structure is plane strain problems, takes the gear of unit width
Cob wall is reduced to spring fastening as the beam on elastic foundation vertically placed, support and anchor pole, and the following soil body of excavation face is adopted in foundation pit
It is simulated with spring, known water pressure is acted on the outside of soil-baffling structure and soil pressure, plane rod piece elastic support method typically calculate
Schematic diagram is as shown in figure 3, a is elastic support made of being simplified as anchor pole in Fig. 3, and b is soil-baffling structure, and c calculates the elasticity of native counter-force
Support.
The width of the finite width soil body between the double cast-in-situ bored pile of supporting scheme (2)+stake end crown beam+stake in coupling beam scheme
Degree is B=9.5m, and excavation of foundation pit depth is H=10.5m, and soil considers according to least favorable situation other than soil blocking component, takes miscellaneous fill
As computing object, severe is γ=17.1kN/m3, cohesive strength c=15.5kPa, internal friction angle isEarth pressure gauge
Calculating point depth is h=10.5m, according to " calculating inquiry of finite soil soil pressure " and " close to existing building foundation pit finite soil
Earth pressure computation method " mentioned method, finite soil width active earth pressure reduction coefficient, calculating process can be calculated
It is as follows:
Rankine Active Earth Pressure coefficient:
Rankine coefficient of passive earth pressure:
Active earth pressure zero point depth after soil blocking component:
The total active earth pressure of Rankine:
Finite width soil body active earth pressure upper limit value:
Finite width soil body soil pressure reduction coefficient:
According to finite width soil body active earth pressure reduction coefficient, according to " building foundation pit supporting technical regulation " (JGJ
120-2012) the 4th chapter provides, is calculated in conjunction with positive deep basal pit software is managed, it is (i.e. main that positive deep basal pit software relevant parameter is managed in adjustment
0.9047) dynamic soil pressure reduction coefficient is revised as, can carry out the calculating of Retaining Structure with Double-row Piles, determine in Double-row-piles Structure and prop up
The parameters such as the stake diameter 800mm of fender pile, length 21.5m, 800 × 1400mm of arrangement of reinforcement 10C32, stake spacing 1000mm and coupling beam size.
After every construction parameter determines, start the construction for carrying out supporting construction:
(1) first construct three branch masks support pile pile body, construct respectively perpendicular to two branch masks in foundation pit sideline
Two rows of cast-in-situ bored piles are parallel to the one gang drill hole pouring pile of supporting surface construction in foundation pit sideline, reach maintenance in support pile pile body
Excavation pit construction stake apical cap beam after phase, it is desirable that excavation of foundation pit width is not less than 10m, excavation of foundation pit absolute altitude and hat bottom elevation phase
Together, and the Single row pillars of three branch masks and double-row pile crown beam one-piece casting；
(2) after reaching crown beam curing period, layer and section excavation pit, and in the first supporting identity distance for being parallel to foundation pit sideline
Position construction first row anchor cable and waist rail from single stake top 2m；
(3) after completing the locking of first row anchorage cable stretching, continue layer and section excavation pit, and hang down apart from first row anchor cable
Directly the position construction second row anchor cable of distance 3m, excavation of foundation pit width are not less than 10m, excavation of foundation pit absolute altitude and second row waist rail bottom
Absolute altitude is identical；
(4) after completing the locking of second row anchorage cable stretching, continue layer and section excavation pit, and hang down apart from second row anchor cable
Directly the position construction third of distance 3m arranges prestress anchorage cable, and excavation of foundation pit width is not less than 10m, and excavation of foundation pit absolute altitude and third are arranged
Waist bottom elevation is identical；
(5) it completes third and arranges prestress anchorage cable tensioning fixation, earth excavation is to foundation pit bottom absolute altitude, both perpendicular to foundation pit side
The earthwork of supporting side, which is also excavated, arrives foundation pit bottom absolute altitude.
The freedom length of the every row's prestress anchorage cable of three row's prestress anchorage cables is not less than 5.0m in the supporting construction, passes through soft
Weak stratum is simultaneously anchored in the soil layer that foundation bearing capacity is more than 100kPa；Anchor cable horizontal spacing is 2 times of stake spacing, first row anchor
For rope apart from 2m at the top of foundation pit, three row's prestress anchorage cable vertical intervals are 3m, and horizontal space is twice of pilespacing, and anchor cable is incident
Angle is 25 °；The lock value of prestress anchorage cable is 160~240kN.The construction of every row's anchor cable successively includes cable body preparation, bores
Hole, cable body decentralization, mortar depositing construction twice, after rope infuses installation and slip casting is completed, carried out on the inside of foundation pit waist beam steel bar colligation,
The construction of waist rail is completed in formwork and concreting, finally carries out anchorage cable stretching locking construction, it is desirable that before binding waist rail reinforcing bar
The tensioning section that anchor cable aperture is reserved is separated using PVC pipe.The anchor cable of each supporting section should continuously construct, crown beam and waist rail
Answer one-piece casting.
Under excavation of foundation pit to the operating condition of depth 10.5m, the displacement of two sides Retaining Structure with Double-row Piles, moment of flexure, shearing are counted
It calculates result to be listed in Fig. 6, the anchored pile supporting displacement for being parallel to foundation pit side, moment of flexure, shear force calculation result is listed in Fig. 7.
As can be seen that using the mentioned supporting scheme of this patent from checkout result figure, supporting construction can satisfy deep pit monitor requirement,
Foundation pit displacement can be preferably controlled simultaneously.
The embodiment project Central Plains supporting scheme is single+three row's prestress anchorage cable of support pile, wherein single support pile is long
30.5m, three row's length of prestress anchor cable are 28.0m, 32.5m, 25.5m；After the mentioned method of this patent, Double-row Piles Support side
The long 21.5m of support pile in case, the long reduction 9m of every support pile stake.If cancelling three row's prestress anchorage cables, supporting is all double
Stake supporting, entire scheme increase by 77.4 ten thousand yuan of cost；And suggested plans using this patent, relatively former supporting scheme at least saves work
Phase 3 months, the duration was converted into cost according to 12% meter of project total cost, can reduce by about 1,200,000 yuan of costs；Comprehensive cost is reduced
42.6 ten thousand yuan, show that this patent is suggested plans with apparent economy.
In conclusion the force-mechanism that the mentioned supporting structure system of the present invention can not only improve supporting construction avoids group anchor
Effect, it is effective to limit foundation pit displacement, improve supporting construction reliability, additionally it is possible to substantially shorten the construction period, and reduce support pile
With anchor cable length, project cost is reduced, there is obviously economy, great application value.
Claims (9)
1. the supporting construction at a kind of concave foundation pit external corner, including two external corner portions being recessed along foundation pit sideline (5-1),
Described two external corner portions are made of three branch masks, and three branch masks and foundation pit sideline (5-1) enclose and set to form concave foundation pit
(5), it is characterised in that: first mask (3) for being parallel to foundation pit sideline (5-1) is by Single row pillars (3-1) and multiple rows of prestressing force
The support system of anchor cable (3-2) composition, Single row pillars (3-1) are equally spaced along the sideline of first mask (3), multiple rows of prestressing force
Anchor cable (3-2) is obliquely squeezed into the soil layer other than foundation pit from the top down along foundation pit inner wall, and first row prestress anchorage cable
1.5~the 2.5m of stake top of (3-2) apart from Single row pillars (3-1)；Perpendicular to second mask (1) of foundation pit sideline (5-1) and third
Branch mask (2) uses Double-row Piles Support system, and the stake spacing of every campshed is not more than twice diameter.
2. the supporting construction at a kind of concave foundation pit external corner according to claim 1, it is characterised in that: in three branch masks
Enclosing construction within the region set has building (4), and the foundation depth of the concave foundation pit (5) is not lend oneself to worry and anxiety not less than in building (4)
The half of degree.
3. the supporting construction at a kind of concave foundation pit external corner according to claim 1, it is characterised in that: second supporting
The Double-row Piles Support system of face (1) and third branch mask (2) includes two rows of cast-in-situ bored piles (1-1) arranged side by side, and every drilling fills
The stake top for infusing stake is equipped with bored concrete pile crown beam (6), is connected between the crown beam of two rows of cast-in-situ bored piles by coupling beam (7) between stake.
4. the supporting construction at a kind of concave foundation pit external corner according to claim 1, it is characterised in that: the prestressed anchor
Rope (3-2) is equipped with three rows, and the vertical interval between three rows is 2.5~3.5m, and horizontal space is twice of pilespacing, and anchor cable enters
Firing angle degree is 20~30 °.
5. the construction method of the supporting construction at a kind of any one of Claims 1-4 concave foundation pit external corner, for concave base
The recessed area in hole is constructed, and recessed area includes three branch masks, and three branch masks form two external corner portions, special
Sign is that specific step is as follows:
(1) according to geology prospecting report, surrounding enviroment condition, excavation of foundation pit depth, the supporting scheme at foundation pit indent position is determined,
The branch mask in foundation pit sideline is parallel to using Retaining Structure with Double-row Piles, is added perpendicular to two masks in foundation pit sideline using Single row pillars
Three row's prestressing anchor support structures；
(2) Rankine's earth pressure theory and plane rod piece elastic support method are used, according to " building foundation pit supporting technical regulation ", in conjunction with
The construction parameter that positive deep basal pit software calculate Single row pillars is managed, and determines the construction parameter of three row's prestress anchorage cables；
(3) using " calculating inquiry of finite soil soil pressure " and " close to existing building foundation pit finite soil active earth pressure meter
Calculation method " mentioned method calculates the finite width soil body and acts on the active earth pressure on Double-row-piles Structure relative to Rankine Earth Pressure
Reduction coefficient, plane rod piece elastic support method is then used, according to " building foundation pit supporting technical regulation ", in conjunction with managing positive deep basal pit
Software calculate the parameter of support pile in determining Double-row-piles Structure；Wherein finite width soil body active earth pressure reduction system
Number calculation formula is as follows:
In formula: B --- finite soil calculates width (m)；
H --- excavation of foundation pit depth (m)；
--- finite width soil body active earth pressure upper limit value (kPa)；
Pa--- the total active earth pressure of Rankine (kPa)；
εa--- finite width soil body soil pressure reduction coefficient；
z0--- active earth pressure zero point depth (m) after soil blocking component；
Ka--- Rankine Active Earth Pressure coefficient；
Kp--- Rankine coefficient of passive earth pressure；
The cohesive strength (kPa) of soil other than c --- soil blocking component；
--- the internal friction angle (°) of soil other than soil blocking component；
(4) after every construction parameter determines, start the construction for carrying out supporting construction, the supporting for three branch masks of constructing first
Stake pile body, perpendicular to foundation pit sideline two branch masks construct respectively two rows cast-in-situ bored piles, be parallel to the supporting in foundation pit sideline
One gang drill hole pouring pile of surface construction, the excavation pit construction stake apical cap beam after support pile pile body reaches curing period, it is desirable that foundation pit is opened
It digs width and is not less than 10m, excavation of foundation pit absolute altitude is identical as hat bottom elevation, and the Single row pillars of three branch masks and double-row pile crown beam
One-piece casting；
(5) after reaching crown beam curing period, layer and section excavation pit, and in the first supporting identity distance for being parallel to foundation pit sideline from list
The position construction first row anchor cable and waist rail of 1.5~2.5m of campshed stake top；
(6) complete first row anchorage cable stretching locking after, continue layer and section excavation pit, and apart from first row anchor cable vertically away from
Position construction second row anchor cable from 2.5~3.5m, excavation of foundation pit width are not less than 10m, excavation of foundation pit absolute altitude and second row waist
Bottom elevation is identical；
(7) complete second row anchorage cable stretching locking after, continue layer and section excavation pit, and apart from second row anchor cable vertically away from
Position construction third from 2.5~3.5m arranges prestress anchorage cable, and excavation of foundation pit width is not less than 10m, excavation of foundation pit absolute altitude and the
Three row's waist bottom elevations are identical；
(8) it completes third and arranges prestress anchorage cable tensioning fixation, earth excavation is to foundation pit bottom absolute altitude, both perpendicular to the supporting of foundation pit side
The side earthwork, which is also excavated, arrives foundation pit bottom absolute altitude.
6. the construction method of the supporting construction at a kind of concave foundation pit external corner according to claim 5, it is characterised in that: institute
Long 2 times not less than excavation of foundation pit depth of stake of the Single row pillars calculated in step (2) are stated, diameter is 0.6~1.0m, stake spacing
For 1.0~1.4m, and it is no more than 2 times of stake diameter；Stake top crown beam width is 200mm bigger than stake diameter, is highly 0.6~0.8m.
7. the construction method of the supporting construction at a kind of concave foundation pit external corner according to claim 5, it is characterised in that: institute
The freedom length of every row's prestress anchorage cable in step (2) is stated not less than 5.0m, across soft stratum and is anchored in foundation bearing
Power is more than in the soil layer of 100kPa；Anchor cable horizontal spacing is 2 times of stake spacing, first row anchor cable away from 1.5~2.5m of ground, remaining
The vertical interval of anchor cable is 2.5~3.5m；The incidence angle of three row's prestress anchorage cables is consistent, is 20 °~30 °；Prestress anchorage cable
Lock value be 160~240kN.
8. the construction method of the supporting construction at a kind of concave foundation pit external corner according to claim 5, it is characterised in that: institute
The construction for stating every row's anchor cable in step (5)~step (7) successively includes cable body preparation, drilling, cable body decentralization, slip casting is applied twice
Work carries out waist beam steel bar colligation, formwork and concreting on the inside of foundation pit and completes waist after rope infuses installation and slip casting is completed
The construction of beam finally carries out anchorage cable stretching locking construction, and the anchor cable of each supporting section is continuously constructed, and crown beam and waist rail integrally pour
It builds.
9. the construction method of the supporting construction at a kind of concave foundation pit external corner according to claim 5, it is characterised in that:
Before waist rail pours in step (5)~(7), tensioning section anchor cable and waist rail concrete are separated using pvc pipe, and pvc pipe penetrates through waist
There is not local damage phenomenon in beam section.
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| CN113585287A (en) * | 2021-08-25 | 2021-11-02 | 中铁第六勘察设计院集团有限公司 | Support structure for combined construction of vertical shaft and foundation pit in TOD mode and construction method |
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