Background technology
The building diaphragm wall is a kind of foundation pit supporting system that is applied to a kind of dash soil-baffling structure of contrary sequence method basement structure construction, is the most frequently used a kind of in several Base hole supporting technology of basement top-down method because it has the big and good characteristics of barrier performance of integral rigidity.
In the prior art, multilayer basement of high-rise building and other multilayer underground structures often adopt reverse construction, promptly utilize the building cover structure of basement, comprise that beam, plate, post etc. and external wall structure are as the horizontal support system of foundation pit enclosure structure with go along with sb. to guard him system, contrary sequence method is the boundary with the datum layer, following each layer basement of datum layer constructed from top to bottom, and the construction from bottom to top simultaneously of above each layer of datum layer is so be called contrary sequence method.Because basement top-down method need guarantee that the basement of building has enough horizontal rigidities from top to bottom, foundation pit deformation is very few, therefore, down is arranged at the foundation pit supporting system that bad soil layer keeps off native usefulness by ground when needing to adopt diaphragm wall as construction.
Diaphragm wall need use special equipment to adopt mud off to excavate out a groove with certain width, thickness and degree of depth along deep foundation or the underground periphery of constructing, its thickness reaches 0.6 meter~1.2 meters, the degree of depth reaches tens meters~tens meters and does not wait, and determines according to the designing requirement and the geological condition of building.Reinforcing cage is set in groove, adopt tremie method concreting in mud, build up several meters wide unit wall section, sequence construction successively, the one continuous underground reinforced concrete wall that unit wall section is connected into certain jointing method, so that antiseepage during excavation of foundation pit, retaining soil, as the supporting on adjacent structure basis and the part that directly becomes the foundation structure of bearing direct load, diaphragm wall will be constructed than in the dark rock stratum more than 2 meters of basement bottom board usually.Its weak point is:
(1) because construction of diaphragm wall needs large-scale special-purpose machinery, and the groove section generally adopts brill, piercing and shaping die, mud off, the cost of operating expenses is higher.
(2) diaphragm wall in hard soil layer and rock stratum, excavate grooving difficulty, particularly rock stratum to bury more shallow be geological conditions when better, and be under the situation of multi-storey basement, the increase of going into rock is very expensive, the construction costs increase is bigger.
(3) being closely connected owing to diaphragm wall and contrary sequence method technology; the cost height of diaphragm wall directly influences basement top-down method The Application of Technology and popularization; but how in the safety of guaranteeing base pit engineering reduction of erection time again; simultaneously again can the Control Engineering cost, become the key issue that influences the contrary sequence method technical development.
Summary of the invention
But the object of the present invention is to provide and a kind ofly guaranteeing under the security situation of base pit engineering not only reduction of erection time but also column supported underground continuous wall that can the Control Engineering cost.
The present invention is a kind of column supported underground continuous wall that adopts the basement top-down method construction, comprise the underground wall body that is provided with along the basement periphery, it is characterized in that described underground wall body is made up of shallow body of wall and dark body of wall, described shallow body of wall is positioned at the top of diaphragm wall, has common diaphragm wall wall body structure, form the closed type body of wall along the basement periphery, retaining soil, dash, impervious when being used for the basement top-down method construction; Described dark body of wall is positioned at the below of shallow body of wall, with discontinuous manner the post that post props up formula embedding rock section is set and props up body of wall, is used to support shallow wall section and as basement floor vertical support structural element, can effectively controls the vertical deformation of diaphragm wall superstructure.Because shallow body of wall has reduced the height of diaphragm wall, dark body of wall post props up body of wall and has reduced the quantity that cost height, diaphragm wall that difficulty is big are gone into the dike section, thus reduction of erection time and reduce cost (referring to Fig. 2,3) greatly.
The present invention is divided into shallow body of wall and dark body of wall two parts with diaphragm wall, shallow body of wall at bad soil body position still adopts existing continuous underground wall structure, dark body of wall at the good position of geological conditions then no longer adopts diaphragm wall structure of the prior art, but having adopted the interruption wall construction, this technical scheme is to be based upon on the basis of the two big characteristics that basement top-down method has to realize.Described two big characteristics are: (1) has the existence of soil arching effect; (2) inner support of contrary sequence method diaphragm wall is protected, and promptly the overall structure of diaphragm wall, floor beam, plate and post formation is utilized its lateral rigidity, and the foundation ditch lateral earth pressure is played a stronger fixed level support effect.At large the technology of the present invention and notion are carried out a large amount of Finite Element Numerical Simulation analyses and monitored data checking and practical engineering application practice through system, confirmed feasibility of the present invention.
When basement top-down method is constructed, what construct at first is basement diaphragm wall all around, while is in relevant position (pillar or the partition wall intersection etc. of interior of building, calculate to determine as required) build or lay the intermediate support stake and post bore the superstructure deadweight and executes the support of load down as construction period before the base plate back cover, after diaphragm wall and the pile completion just from top to down successively carry out the construction of excavation of foundation pit and floor beam, plate.The beam slab floor structure of elder generation's construction datum layer, the first road horizontal support on the diaphragm wall top around forming, the significant horizontal rigidity of floor structure becomes the very big support of diaphragm wall, utilize diaphragm wall retaining soil subsequently, successively earth excavation and build each layer underground structure downwards until the base plate back cover.In this work progress, no matter whether underground diaphragm wall is added interim horizontal support with the soil pressure of balanced action on diaphragm wall, when whenever finishing first floor bent cap plate, the capital makes diaphragm wall form many one horizontal supports, make the inner support of diaphragm wall be protected, be that diaphragm wall, floor beam, plate and pile have formed an overall space structure that rigidity is huge, can play a stronger fixed level support effect the lateral earth pressure that acts on the diaphragm wall.
Although the geological condition of each building operations all is not quite similar, but the geological conditions of common buildings construction just comprises two parts soil body nothing more than, the part soil body is the bad soil body that is positioned at the ground table top, moisture water permeability is stronger, the soil is porous, represents the angle of internal friction α (referring to Fig. 1) of soil body stability less, when carrying out excavation of foundation pit in the mode of opening wide, cause soil body landslide easily, the angle on landslide and the angle of internal friction α of this soil body match.Miscellaneous fill layer, mud, layer of sand, plastic farinose argillic horizon etc. all belong to the bad soil body.Another part soil body is the good soil body that is positioned at bad soil body below, and soil (rock) matter is closely knit, and intensity hardness is higher, and bad hydraulic permeability is even not permeable, and angle of internal friction α is bigger, generally is severely-weathered to middle weathered rock formation and gentle breeze rock stratum.The degree of depth of the bad soil body of different regions can be different, and according to China's north and south geology difference condition, depth difference southern, the northern bad soil body can reach 20~30 meters more than, and the degree of depth of the southern bad soil body is less, and the degree of depth of the northern bad soil body is bigger.
When basement top-down method is constructed, be positioned at the bad soil body on foundation ditch top, owing to the basement overall structure that has diaphragm wall and flooring beam slab, pile etc. to form, its rigidity is huge, is enough to the slippage that stops that soil layer produces.Therefore, the sliding rupture of the foundation pit side-wall at bad soil body position is almost non-existent.And when soil (rock) layer position continuation preferably excavated downwards, the below soil body of excavation is not as the supporting-point of the soil mass of foundation pit of exposing out, the top basement of rigid body formula is then as foundation ditch upper support point, can in the excavation face soil body, form soil arching effect (referring to Fig. 4) after the last lower support, make that the soil pressure that acts on this position space enclosing structure is less with joint efforts, can play the effect that stops unsupported soil body slipping, protuberance.In suitable altitude range, adopt present technique, can reasonably utilize the physical characteristic of better soil layer itself to reach homeostatic effect, retaining soil to this position requires just can reduce greatly, if what enter is not weathering or gentle breeze rock stratum, even can consider to keep off native requirement, adding need not have the sealing requirement after entering waterproof soil (rock) layer yet, diaphragm wall at this position in fact only plays load-bearing, so, just need not the equal build-in of all wall sections and go into hard soil layer, only need post to be set and prop up body of wall with certain spacing, can realize the effect of its load-bearing and vertical supporting member, save most of conventional retaining wall member at this position and become possibility thereby make.
Shallow body of wall height of the present invention is as the criterion with the degree of depth of the bad soil body in the actual geology, and its height should be enough to cover whole bad solums, can fully play the effect of dash, retaining soil to guarantee shallow wall section.
Shallow wall section of the present invention preferably can extend under the basement superstructure absolute altitude at bad soil body depth capacity place, is beneficial to guarantee the firm of support system.
The height of dark wall section of the present invention is shallow wall section with down to place, the following rock stratum of base plate of foundation pit, and shallow wall section and dark wall section boundary should be located in the scope of the 300~1500mm of basement superstructure absolute altitude under sentencing, and preferable range is 400~1000mm.
The present invention can do following improvement: at described dark wall part, every two adjacent posts prop up spacing between the body of wall in 10~30 meters scope; Preferable range is 15~20 meters.
The present invention can do following improvement: because the discontinuous post of the dark body of wall of the present invention props up body of wall, make shallow body of wall become unsettled wall section in the wall section that two posts of dark body of wall prop up between the body of wall, and shallow body of wall is to divide a plurality of cell width construction molding and constituting one by one with whole diaphragm wall, general i shaped steel or the similar member of adopting vertically engages between each unit body of wall, therefore, for strengthening the transverse strength of diaphragm wall, described diaphragm wall and basement wall can be combined into an integral body, basement wall abbreviates the inwall wall as, and the transverse reinforcement structure that the inwall wall that utilizes construction successively to form is had improves the transverse strength of the unsettled wall section of diaphragm wall.Concrete technical measures are pre-buried a plurality of reinforcing bars that are used to connect the inwall wall on described diaphragm wall inner face, described inwall wall is close to the diaphragm wall moulding, the pre-buried reinforcing bar part of described diaphragm wall stretches in the inwall wall, when inwall wall moulding by casting, be fixed on wherein, thereby make two bodies of wall in conjunction with as a whole.
The present invention can also further be installed on the first floor collar tie beam top of the shallow body of wall section of diaphragm wall, and shallow body of wall top is provided with longitudinal reinforcement, links to each other with first floor collar tie beam, utilizes the transverse strength of collar tie beam to improve the transverse strength of shallow body of wall; Remaining every layer collar tie beam all is embedded in and waters into complete firm one in the diaphragm wall inwall wall in the lump, makes unsettled wall section of the shallow body of wall that is combined into one and inwall wall become Continuous Deep Beam, further strengthens the structural strength of the unsettled wall section of the shallow body of wall of diaphragm wall.
Diaphragm wall of the present invention is in all and flooring Vierendeel girder junction, pre-buried pvc pipe, chisel with Vierendeel girder with operation after an action of the bowels and to be connected, the reinforcing cage fixation of built-in fitting and crossbeam, flooring Vierendeel girder and diaphragm wall are rigidly connected, change the out-of-date methods of in the past using girder steel box built-in fitting, can save a large amount of steel, simplify working process.
The present invention can also do further improvement: prop up at adjacent two posts of described dark body of wall the combined bolting and shotcrete combined member is set between the body of wall, promptly when geological conditions is good, utilize between the upper strata support and the excavation face soil body and can form favourable soil arching effect, the foundation pit side-wall that post in per two following rock stratum of embedding base plate props up between the wall section is done combined bolting and shotcrete, comprise with anchor pole or soil nailing fixing with wire lath on foundation pit side-wall and sprayed mortar, form thin wall construction with the effect of certain retaining soil.Can in surpassing 10 meters dark deep layer basement foundation ditch sidewalls, use, in the reverse construction of ultra-deep foundation pit, save great amount of investment.
Compared with prior art there is following advantage in the present invention:
1, the present invention adopts the column supported underground continuous wall that comprises shallow body of wall and dark wall body structure as the bracing of foundation pit member, shallow body of wall is used conventional Diaphragm Wall, post in conjunction with the interval setting of body of wall deeply props up the formula body of wall, utilize the acting in conjunction of the horizontal support of the approximate rigid body that good native arching action and diaphragm wall top had, both guaranteed the homeostatic effect of lower floor's soil body, reduce the degree of depth of diaphragm wall again effectively and reduced the cost height, the diaphragm wall that difficulty is big is gone into the quantity of dike section, reduction reaches 20%~40%, thereby reduced material usage and gone along with sb. to guard him measure, shorten the construction period, greatly reduce engineering cost.
2, the present invention can be combined into an integral body with diaphragm wall and basement wall, both strengthened the transverse strength of the unsettled wall section of the shallow body of wall of diaphragm wall, and saved the enclosure wall of setting up separately again, and can in the land used scope, enlarge the effective usable floor area of basement to greatest extent;
3, it is one that the present invention waters complete strong bonded in the lump with the inwall wall at the first floor or every layer of collar tie beam and the unsettled wall section of shallow body of wall place, can prop up the wall section to post in the design and regard the bearing that suspends body of wall in midair as, unsettled wall section and inwall wall integrally combine and become Continuous Deep Beam, beam column and anchor pole by vertical direction supports again, constitute a stable space frame system, solved simple employing diaphragm wall well and made the high problem of pattern foundation pit supporting structure cost;
4, the present invention with diaphragm wall in conjunction with the combined bolting and shotcrete combined member, be implemented in the retaining soil effect that dark body of wall is interrupted the place, space with lower cost, can in surpassing 10 meters dark deep layer basement foundation ditch sidewalls, use, in the reverse construction of ultra-deep foundation pit, save great amount of investment.
5, the present invention is mainly used in the design and the construction of basement more than three layers, successfully apply to a plurality of high levels (superelevation layer) deep foundation pit of construction engineering, obtained remarkable economic efficiency, to the development of deep foundation ditch contrary sequence method design and construction technology and improve the deep foundation ditch soil body and the research of structure stress mechanism has great academic significance, and in engineering practice, have wide practical use.
The specific embodiment
Embodiment 1
A kind of column supported underground continuous wall that adopts basement top-down method to construct shown in Fig. 2~5 is one of embodiment of the invention, comprise the underground wall body that is provided with along the basement periphery, it is characterized in that described underground wall body is made up of shallow body of wall 11 and dark body of wall 12, described shallow body of wall 11 is positioned at the top of diaphragm wall 1, has common diaphragm wall wall body structure, form the closed type body of wall along the basement periphery, cover whole bad soil body A, retaining soil, dash, impervious when being used for the basement top-down method construction.Shallow body of wall combines the basement superstructure that constitutes with superstructure 4, beam 5 and post 3, have huge lateral rigidity, and suffered lateral earth pressure displacement is less, and the fixed level that can regard as the soil body supports.
Described dark body of wall 12 extends the embedding rock under the below of shallow body of wall, utilize completed basement superstructure as upper bracket, the hole hard soil in the end (rock) is as undersetting, under the effect of lateral earth pressure, form soil arching effect C and guarantee homeostasis, thereby can save the dash of this part, soil-baffling structure, with discontinuous manner the post that post props up formula embedding rock section is set and props up body of wall, the spacing that every two adjacent posts prop up between the body of wall is 18 meters, be used for supporting at the good foundation ditch soil layer position B of geological conditions, rise and support shallow body of wall 11 and, effectively control the vertical deformation of diaphragm wall superstructure as basement floor vertical support structural element.
Embodiment 2
Column supported underground continuous wall shown in Fig. 6~10 is two of embodiments of the invention, different with last example is, the spacing of propping up between the body of wall at dark body of wall 12 two the adjacent posts of diaphragm wall is 20 meters, combined bolting and shotcrete combined member 2 is set in this spacing, promptly prop up and use combined bolting and shotcrete between the body of wall instead at adjacent post, promptly wire lath is fixed on the foundation pit side-wall sprayed mortar again, forms thin wall construction with the effect of certain retaining soil with soil nailing 21 is fixing.In addition, anchor pole 22 is squeezed in also shallow body of wall bottom, with the horizontal support of the shallow body of wall of further reinforcement.
Shown in Fig. 6,8,9, the shallow body of wall of diaphragm wall is to divide a plurality of cell width construction molding and constituting one by one with whole diaphragm wall, the general i shaped steel 13 that adopts engages between each unit body of wall, and steel truss 14 and horizontal, vertical muscle 15 and 16 are all arranged in each unit wall.Diaphragm wall 1 is combined into an integral body with inwall wall 6, described inwall wall 6 is close to the diaphragm wall moulding, its height from shallow body of wall 11 tops until dark body of wall 12 bottoms, inwall is provided with within the walls and is provided with equally laterally, vertical muscle 61 and 62, and different is that horizontal bar 61 is to link up in whole body of wall.Inwall wall 6 is less at shallow body of wall 11 position thickness, and during to dark body of wall 12 positions, two posts prop up the below of the unsettled body of wall of shallow body of wall between the body of wall, and inwall wall 6 also is close to the combined bolting and shotcrete formable layer, fills up the space of the unsettled body of wall of shallow body of wall below.
As shown in Figure 9, pre-buried many connecting reinforcements 7 that are used to connect inwall wall 6 on described diaphragm wall 1 inner face, connecting reinforcement is made of one section reinforcing bar, it is embedded in the shallow body of wall 11 for straight pre-buried section 71 so that the centre is a bit of, pre-buried section two ends are to shallow body of wall inner surface direction cross folding, to fold the mode of pulling out with " * " at two ends 72 when carrying out the construction of inwall wall stretches in the inwall wall zone, when building moulding, the inwall wall is fixed on wherein, the inwall wall is close to the diaphragm wall moulding, makes two bodies of wall in conjunction with as a whole under the effect of connecting reinforcement 7.Be provided with complete vertical muscle and transverse reinforcement in the inwall wall, can improve the transverse strength of the unsettled wall section of shallow body of wall.
Shown in Fig. 6,7,10, basement first floor collar tie beam 51a is installed on the top of the shallow body of wall section of diaphragm wall, and shallow body of wall top is provided with longitudinal reinforcement, links to each other with first floor collar tie beam, utilizes the transverse strength of collar tie beam to improve the transverse strength of shallow body of wall; Remaining every layer collar tie beam 51b is embedded in the unsettled wall section of the diaphragm wall place inwall wall and waters into complete firm one in the lump, makes unsettled wall section of the shallow body of wall that is combined into one and inwall wall become Continuous Deep Beam.
Described diaphragm wall is in all and flooring Vierendeel girder junction, pre-buried pvc pipe and stiffener, so that dig out the connection breach, and Vierendeel girder reinforcing bar 52 is stretched into, flooring Vierendeel girder and diaphragm wall are rigidly connected, change the out-of-date methods of in the past using girder steel box built-in fitting, can save a large amount of steel, simplify working process.