CN102477744B - Pit excavation method in large-area pit with internal support under condition of soft soil foundation - Google Patents
Pit excavation method in large-area pit with internal support under condition of soft soil foundation Download PDFInfo
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Abstract
The invention relates to a deep foundation pit excavation method under the condition of a soft soil foundation, in particular to a pit excavation method in a complicated deep foundation pit group large-area pit under the condition of the soft soil foundation. The pit excavation method in a large-area pit with an internal support under the condition of the soft soil foundation is characterized in that a supporting method comprises the following steps of: step 1, reinforcing soft soil in the foundation pit and improving the engineering performance of the soft soil; step 2, arranging a tower crane to conveniently and quickly install the support; step 3, symmetrically blocking and synchronously excavating; step 4, retreating into excavation in a fan shape and simultaneously excavating and supporting; and step 5, timely blocking and pouring a foundation bottom plate. The invention has the beneficial effects that the soil excavation efficiency is improved, the foundation pit deformation and the simultaneous supporting and excavation are effectively controlled, the soil excavation difficulty is reduced, the soil excavation efficiency is improved, the construction cost is reduced, and the safety of the foundation pit is ensured.
Description
Technical field
The present invention relates to deep foundation pit of soft soil foundation excavation, relate in particular under Soft Soil and cheat excavation method in complicated deep group large area band inner support hole.
Background technology
Under Soft Soil, in complicated deep group hole, the characteristic feature in hole is: high-moisture percentage plastic flow mud layer, and undisturbed soil is weak, has high-compressibility and rheological characteristic, and after reinforcing improvement, soil property still belongs to weak soil category; Deep foundation ditch group area is large, absolute altitude changes complexity, arranges by different level space enclosing structure, and combination supporting is large with pit area in the hole of inner support supporting, and the similar rectangle of shape is positioned at deep foundation ditch group middle part; Zhong Keng position, hole is individual layer standard steel pipe inner supporting, and being supported to the end, hole distance is the effective cutting depth of backhoe digging machine.
For large scale industry production line project, due to raw materials for production and product communications and transportation needs, addressing is general near river, river estuary, coastal Soft Soil Area.And the logical undisturbed soil moisture content in this area, high soil property is weak, has high-compressibility and rheological characteristic, even still belong to weak soil category after artificial soil stabilization; The apparatus for production line of the large scale industry simultaneously basis scale of construction is large, buried depth is dark, basic plane is irregular and absolute altitude changes complexity, and foundation ditch distributes in groups, and Zhong Keng position, hole area is larger, in whole support system, and hole band inner support supporting conventionally in hole.Because soil property is weak, and the restriction of inner support, make to cheat Zhong Keng position and cut the earth very difficultly, and in hole to cut the earth be the key of the whole foundation pit deformation of impact in hole, security risk is very large.In recent years soft soil along the coast because hole in hole is cut the earth mishandling, cause that space enclosing structure is caved in, " skirt, make dumplings " or the inside and outside distortion excess of foundation ditch, stake, pile breaking phenomenon happen occasionally to cause large area engineering pile, even, due to foundation pit collapse generation human casualty accident, to people's lives and properties, cause very big loss.
Therefore, technician reaches common understanding, and after the first support that needs in such cases to adopt, digs, and space enclosing structure distortion can finely be controlled, but be with to support, cut the earth or supports quite difficulty of lower shoveling, and shoveling efficiency is low; Although first dig back brace mode shoveling efficiency, can increase substantially, space enclosing structure Deformation control difficulty is large, if support, installs and can not catch up with in time, may lead to disastrous consequence.
Summary of the invention
The present invention is intended to address the above problem, and provides under a kind of Soft Soil and cheats excavation method in large area band inner support hole.The present invention improves shoveling efficiency, effectively controls foundation pit deformation temple limit and digs, and has reduced shoveling difficulty, has improved shoveling efficiency, has reduced construction cost; Guarantee foundation ditch safety.
The present invention is achieved in that under a kind of Soft Soil, large area band inner support is cheated excavation method in cheating, and described supporting method comprises the steps:
Step 1: weak soil in foundation ditch is reinforced, improved its engineering property;
Step 2: the convenient and swift installation of tower crane is set and supports;
Step 3: symmetrical piecemeal synchronously excavates;
Step 4: " fan-shaped " setback is cut the earth, and temple is dug on limit;
Step 5: timely block placement sole plate.
Under described Soft Soil, in large area band inner support, cheat excavation method, described step 1 comprise at the bottom of Foundation Pit and weak soil to be dug reinforce, increase soil strength, improve base bottom heave drag and shoveling and put the slope gradient.
Under described Soft Soil, in large area band inner support hole, cheat excavation method, in described step 1, to soil stabilization and improve performance requirement and comprise:
A) for natural moisture content ω ﹤ 50%, natural air space ratio e ﹤ 1.5, osmotic coefficient k > 10
-6cm/s, grogs formation and permeability are suitable for the general weak soil of precipitation, can adopt deep-well or light shape well point drainage precipitation method to carry out the fixed soil strength that improves;
B) for natural moisture content ω > 50%, natural air space ratio e > 1.5, osmotic coefficient k < 10
-6cm/s, grogs forms and permeability is unsuitable for the special defects weak soil of precipitation, or even stream moulds shape mud, can adopt the stake of deep cement-mixed pile " grid " row of piles to reinforce indigenous method in the end, hole and hole and improve soil strength;
C) after reinforcement of soft soil, soil body engineering property has corresponding raising, after reinforcement of soft soil improves, its moisture content target should be controlled at below 40%, C, φ value target should be controlled at 30.0Kpa and more than 15.0 °, make shoveling put slope ratio and can be controlled in 1:1, guarantee that backhoe digging machine can the disposable substrate design absolute altitude that is excavated to.
D) in conjunction with the setting of symmetrical piecemeal in " step 3 ", " cross " high density stabilization zone is set in hole in hole, strengthening bearing capacity of foundation soil, prepares for be unearthed vehicle or digging machine travel; To span centre piecemeal, district reinforces especially, as last foundation ditch receive dirt road road and in digging process as temporary supporting earth dam in the long end bay of space enclosing structure, with finite constraint span centre space enclosing structure, be out of shape.
4, under Soft Soil according to claim 1, in large area band inner support hole, cheat excavation method, it is characterized in that: described step 2 is included in foundation ditch outside tower crane is set, tower crane lifting capacity and effectively lift by crane radius according to tower crane setting position and the selected the longest single-unit weight of standard steel pipe support, be supported to tower crane distance and select; In soft base, the existing engineering pile of tower crane utilization or increase arrange bored pile.
5, under Soft Soil according to claim 1, in large area band inner support hole, cheat excavation method, it is characterized in that: described step 3 comprises carries out refinement piecemeal to hole in large area hole, piecemeal principle is symmetrical equilibrium, every fritter area is no more than 900m2, along with the increase piecemeal area of foundation depth further reduces.
6, in large area band inner support hole, cheat excavation method under Soft Soil according to claim 1 or 5; It is characterized in that, in described step 3, to hole in similar rectangle hole, along the even piecemeal in the long limit of space enclosing structure, first symmetrical synchronous excavating structure minor face two, after treating that piecemeal district, two sole plate is built, excavate piecemeal in long end bay, soil outlet is arranged in long end bay one or both sides again.
7, under Soft Soil according to claim 1, in large area band inner support hole, cheat excavation method, it is characterized in that: described step 4 comprises " fan-shaped " setback shoveling in hole in hole, and temple is dug on limit, and its concrete steps and cooperation method are:
One of: first, from four jiaos of symmetrical " fan-shaped " inner arc excavations of foundation ditch, digging machine is advanced to foundation ditch middle part direction, and interior camber line rise is controlled and is not more than angle brace spacing;
Two: again from both sides minor face to the long end bay of space enclosing structure, direction " fan-shaped " inner arc moves back and digs, and interior camber line rise is controlled and is not more than 1.2 times of support intervals;
Three: after treating piecemeal district, both sides bottom slab concreting, to unearthed direction " fan-shaped " outer arc, move back and dig in long end bay piecemeal soil, complete shoveling work.
Four: backhoe is moved back in shoveling traveling process (now not adding support zone enclosure wall inner side still has a certain amount of waiting to cut the earth) when camber line summit approaches or slightly surpasses next Support Position in " fan-shaped " and is suspended and cut the earth, transfer to tower crane lifting standard support, coordinate setback and so forth until support installs, excavation of foundation pit is complete.
8, according to cheating excavation method in large area band inner support hole under the Soft Soil described in claim 1 or 7, it is characterized in that: described " fan-shaped " setback is cut the earth and referred to that mouth line of the domatic end of soil excavation becomes " fan-shaped " camber line, backhoe digging machine regression excavation, at the bottom of backhoe digging machine erect-position, mouth line is " fan-shaped " interior camber line or " fan-shaped " outer camber line relatively
9, under Soft Soil according to claim 1, in large area band inner support hole, cheat excavation method, it is characterized in that: described step 5 comprises according to piecemeal excavation sequence builds sole plate in time, in hole, cheat piecemeal see the bottom to sole plate, build the complete duration should be over 7 days, the darker piecemeal area of foundation ditch is larger, and the time should be shorter.
" fan-shaped " camber line setback excavation in the present invention, the method for temple is dug on limit, has embodied a kind of support replacement excavation concept, has broken through in traditional weak soil and has first supportted and dig afterwards limitation, has solved well excavation efficiency and safety problem; Piecemeal excavation, the shoveling of " fan-shaped " camber line setback, the employing of bottom sealing method in time simultaneously, make full use of the correlation for the treatment of shoveling, support, space enclosing structure in foundation ditch, and the EFFECT OF OPPORTUNITY ON of cooperation, the development of deformation of foundation ditch in digging process is controlled in active effectively.The present invention has avoided first supportting and has dug afterwards shoveling operating mode under the support bringing, and greatly reduces shoveling difficulty, has improved shoveling efficiency, has reduced construction cost; Simultaneously by piecemeal excavate, " fan-shaped " setback is cut the earth, the method such as back cover in time, the development of ACTIVE CONTROL foundation pit deformation, guarantees foundation ditch safety.Band inner support of the present invention is cheated shoveling method under prior art background condition in hole, has very large popularization and application space.
Accompanying drawing explanation
Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail:
Fig. 1 is that foundation ditch of the present invention is arranged sketch;
Fig. 2 is fan-shaped excavation schematic diagram of the present invention.
The specific embodiment
Please refer to Fig. 1 and Fig. 2, a kind of large area band of the present invention inner support is cheated excavation method in hole, and implementation method and principle are as follows:
Step 1: weak soil in foundation ditch is reinforced, improved its engineering property;
Step 2: the convenient and swift installation of tower crane is set and supports;
Step 3: symmetrical piecemeal synchronously excavates;
Step 4: " fan-shaped " setback is cut the earth, and temple is dug on limit;
Step 5: timely block placement sole plate.
Described large area band inner support is cheated excavation method in hole, described step 1 comprise at the bottom of Foundation Pit and weak soil to be dug reinforce, increase soil strength, improve base bottom heave drag and shoveling and put the slope gradient.Soil stabilization and improve performance requirement:
A) for natural moisture content ω ﹤ 50%, natural air space ratio e ﹤ 1.5, osmotic coefficient k > 10
-6cm/s, grogs formation and permeability are suitable for the general weak soil of precipitation, can adopt deep-well or light shape well point drainage precipitation method to carry out the fixed soil strength that improves;
B) for natural moisture content ω > 50%, natural air space ratio e > 1.5, osmotic coefficient k < 10
-6cm/s, grogs forms and permeability is unsuitable for the special defects weak soil of precipitation, or even stream moulds shape mud, can adopt the stake of deep cement-mixed pile " grid " row of piles to reinforce indigenous method in the end, hole and hole and improve soil strength.Reinforcement with Cement-mixed Piles scope one is following certain thickness at the bottom of foundation ditch, play the anti-protuberance ability of foundation ditch that strengthens, the 2nd, reinforce the hole end above spoil part soil body, improve the soil body self shear behavior, guarantee can stay when excavation to establish compared with the steep gradient, to be not interposing to produce landslide or produce soil creep and cause engineering pile broken pile or fall stake.
C) after reinforcement of soft soil, soil body engineering property has corresponding raising, after reinforcement of soft soil improves, its moisture content target should be controlled at below 40%, C, φ value target should be controlled at 30.0Kpa and more than 15.0 °, make shoveling put slope ratio and can be controlled at 1:1 left and right, guarantee that backhoe digging machine can the disposable substrate design absolute altitude that is excavated to.Side slope is kept somewhere in the better shoveling of soil stabilization effect temporarily can be steeper, and under cutting depth one stable condition, digging machine brachium can be shorter, otherwise that digging machine need be selected is long-armed, cuts the earth and support to install to coordinate the difficulty that becomes.
D) in conjunction with symmetrical piecemeal setting in " step 3 ", " cross " high density stabilization zone is set in hole in hole, strengthening bearing capacity of foundation soil, prepares for be unearthed vehicle or digging machine travel; Especially span centre piecemeal district reinforces especially, and one is used as the last foundation ditch road that is unearthed, two in digging process as temporary supporting earth dam in the long end bay of space enclosing structure, can finite constraint span centre space enclosing structure be out of shape.
Described large area band inner support is cheated excavation method in hole, it is characterized in that: described step 2 is included in foundation ditch outside suitable tower crane is set, for quick handling, installation steel pipe support.Tower crane lifting capacity and effectively lift by crane radius according to tower crane setting position and the selected the longest single-unit weight of standard steel pipe support, be supported to tower crane distance and select; Tower crane should be arranged at nearly span centre place, the long limit of space enclosing structure, and is positioned at the unearthed side of span centre; Tower crane model is selected to leave necessary safety stock, and in soft base, tower crane should utilize existing engineering pile or increase that bored pile is set, must be reliable and stable.
In described large area band inner support hole, cheat excavation method, described step 3 comprises carries out refinement piecemeal to hole in large area hole, piecemeal principle is symmetrical equilibrium, and every fritter area is (in conjunction with sole plate form) below 30m is square, along with the increase piecemeal area of foundation depth should enter one, reduces.To hole in similar rectangle hole, should be along the even piecemeal in the long limit of space enclosing structure, first symmetrical synchronous excavating structure minor face two, after treating that piecemeal district, two sole plate is built, then piecemeal in the long end bay of excavation, soil outlet is arranged in long end bay one or both sides.The benefit of the synchronous excavation of symmetrical piecemeal is: 1) generous amount soil is resolved into relative fritter soil, be convenient to dig, transport machinery, cut the coordination coordinated of stake machinery and auxiliary manpower, can effectively control shoveling rhythm, improve shoveling usefulness; 2) utilize the interim soil of keeping somewhere, shorten space enclosing structure horizontal span, the stressed and development of deformation of active accommodation support system, initiatively delays the speed that support system reaches design stress and distortion; 3) deadweight of keeping somewhere Dai Wakuai district soil after piecemeal retrains the hole protuberance development of deformation at the end well; 4) large foundation ditch is converted into little foundation ditch, defeats in detail, convenient hole end fast pouring structure base slab, guarantees foundation ditch safety, and every Division area is just being suitable for the requirement that mass concrete invert piecemeal is jumped storehouse construction, also for structure construction creates favorable conditions; 5) symmetrical, synchronous excavation can make the distortion of space enclosing structure evenly develop, and guarantees the stable of space enclosing structure and support system.
In described large area band inner support hole, cheat excavation method, described step 4 comprises " fan-shaped " setback shoveling in hole in hole, and temple is dug on limit." fan-shaped " setback is cut the earth and is referred to that mouth line of the domatic end of soil excavation becomes " fan-shaped " camber line, backhoe digging machine regression excavation, and at the bottom of backhoe digging machine erect-position, mouth line is " fan-shaped " interior camber line and " fan-shaped " outer camber line relatively.Hole " fan-shaped " setback in similar rectangle hole is cut the earth, and the concrete steps that temple limit is dug and cooperation method are:
A) step 1: first, from four jiaos of symmetrical " fan-shaped " inner arc excavations of foundation ditch, digging machine is advanced to foundation ditch middle part direction, and interior camber line rise is controlled and is not more than angle brace spacing;
B) step 2: again from both sides minor face to the long end bay of space enclosing structure, direction " fan-shaped " inner arc moves back and digs, interior camber line rise is controlled and is not more than 1.2 times of support intervals;
C) step 3: after treating piecemeal district, both sides bottom slab concreting, move back and dig piecemeal soil in long end bay to unearthed direction " fan-shaped " outer arc, complete shoveling work.
D) backhoe is moved back in shoveling traveling process (now not adding support zone enclosure wall inner side still has a certain amount of waiting to cut the earth) when camber line summit approaches or surpasses next Support Position in " fan-shaped " and is suspended and cut the earth, transfer to tower crane lifting standard support, coordinate setback and so forth until support installs, excavation of foundation pit is complete.
To similar rectangle foundation pit, first, from four jiaos of " fan-shaped " inner arc excavations, camber line rise is controlled at and is not more than angle brace spacing, and well the initial deformation of firm bight space enclosing structure is suitable, to whole foundation pit enclosure structure structural strain's, controls highly beneficial; From enclosure wall minor face " fan-shaped " inner arc to long end bay, move back and dig, can expand excavation face on the one hand, increase digging machine footprint, can delay on the one hand the end uplift of soil distortion of supporting toe of wall hole, and body of wall introversion distortion.When foundation pit earth consolidation effect is better, adopt limit to dig temple scheme.When the summit regression of " fan-shaped " inner arc is to next Support Position, or omit while surpassing next Support Position, suspend and cut the earth, tower crane starts to install support, basic and the inner support consistency from top to bottom of the mouth camber line line of the domatic end of now cutting the earth, go along with sb. to guard him toe of wall leave part wait to cut the earth, support installs rear continuation " fan-shaped " inner arc setback and cuts the earth, existence due to " fan-shaped " inner arc, after support is added, middle part still has under digging machine shovels space, make to support the remaining soil excavation in place, corner and become relatively easy, whole process is similar to circulation support replacement formula and cuts the earth, to cheating, the end, is stable and the long limit of enclosure wall Deformation control is highly beneficial, when being about to setback to bracing of foundation pit wall structure span centre and receiving native position, by inner arc " fan-shaped ", move back and dig, changing outer arc " fan-shaped " into moves back and digs, receiving Tu Kou position on the one hand narrows down conventionally, arrange that digging machine quantity reduces, be unearthed slowly, it is longer to tidy up the remaining soil time of toe of wall position, foundation ditch is about to all be shaped on the one hand, minimizing along with soil in hole, under the soil pressure and additonal pressure effect of surrounding supporting and protection structure periphery, in bottom heave Deformation Theory, can on peak value, increase development, and slippage radius becomes increase tendency development, outer arc " fan-shaped " setback is cut the earth, the foundation ditch central part that can the slow down speed that fetches earth, stabilized baseplate development of deformation speed.
In described large area band inner support hole, cheat excavation method, it is characterized in that: described step 5 comprises according to piecemeal excavation sequence builds sole plate in time.In foundation ditch, cut the earth is the essential reason that produces foundation pit deformation.Foundation ditch bottom heave has the reason of two aspects: the one, and the inside and outside earth pressure balance in hole is broken, and the outer soil in hole can move as circular arc around supporting and protection structure; The 2nd, after the end saturated soil release of hole, partly there is resilience in elastic compression in self pore water pressure and the soil body.The distortion that these two kinds of reasons produce is all irreversible, and protuberance deflection is directly proportional with substrate open-assembly time, and especially in Soft Soil Layer, proportional relation shows more obvious in this.Therefore the fastest speed is carried out foundation structure construction of bottom plates to the greatest extent, to carrying out back cover in the end, hole, utilizes the dead-weight balanced soil pressure of steel concrete, very crucial important.In the soft base deep foundation ditch group of piecemeal excavation, must accomplish see the bottom one of a bottom slab concreting of foundation ditch, definitely can not allow substrate expose the long time.In hole, cheat piecemeal and see the bottom and to sole plate, build the complete duration and should not surpass 7 days, the darker piecemeal area of foundation ditch is larger, and the time should be controlled shorter.
Embodiment
As shown in the figure: in certain steel plate Co., Ltd pickling-production line of rolling mill engineering, milling train district deep foundation ditch is mined massively by staged layering combination supporting mode, wherein in hole, underground oil depot of rolling mill district, hole is positioned at foundation ditch group central authorities, in hole, hole adopts the supporting of steel sheet pile+steel pipe inner supporting, supporting scope is-5.7m ~-10m that to natural ground, peripheral foundation ditch surrounding adopts Gravity Retaining Wall supporting to-5.7m.The long 90m in hole in hole, wide 40m, area is larger, earthwork excavated volume 1.5 ten thousand sides.In hole, cheating inner support is φ 609 * 12 standard steel pipe supports, support interval 4.5m, and angle brace spacing 3m is established in foundation ditch bight.Foundation ditch region is plastic flow mud, moisture content w=30 ~ 90%, average 58.8%; Void ratio e=1.625, compression coefficient a
v1-2=1.223MPa
-1; Compression modulus Es=2.0MPa, natural density ρ
0=1.6g/cm3, cohesion C
k=7.5KPa, angle of internal friction Φ
k=4.1 °.
Implementation step is as follows:
Step 1, in conjunction with whole foundation ditch group's soil stabilization scheme, to soil in following and above hole at the bottom of hole, Zhong Keng position, hole, adopt deep cement-mixed pile to reinforce.Agitation pile cement mixing content: within the scope of the following 4m in the end of hole 15%, above face portion 5% extremely naturally, reinforcing pile bottom 15%, and different addition quantity is controlled by the stirring pile hoisting velocity of whitewashing in top 5%.Agitation pile adopts wet method, and four stir two spray method piles, and stake machine is 2 φ 700 Double shaft stirring stake machines.Agitation pile, by " well " glyph grid formula campshed, faces pile body interlock overlap joint, mesh spacing 2.5m mutually.In hole, cheat long and short limit center line " ten " font is set, two agitation piles are encrypted band, encrypt bandwidth 6m, to strengthening the reserved passage that is unearthed of doing of local soil strength.Reinforce maintenance after 40 days, take a sample test pile body core unconfined compression strength average 0.4 ~ 0.6 Mpa.
Step 3, as in " cheating inner support layout sketch in hole ", " cheat in hole fan-shaped setback excavation simplified schematic diagram ", along hole in hole long to 1. foundation ditch is divided into, 2., 3. three excavations, approximately 1200 square metres of every areas, span centre piece area reduces.Wherein the 1., 2. piece symmetrical excavation simultaneously, the 3. piece the 1. treat, 2. after piece foundation structure bottom slab concreting, excavate again.The 3. piece stay last excavation, the one, large foundation ditch is resolved into little foundation ditch, reduce bottom heave, the 2nd, solved unearthed path problem, the 3rd, at foundation pit enclosure structure span centre, form and support " earth dam ", can the distortion of operative constraint space enclosing structure.
Step 4, according to step 3 piecemeal excavation sequence, first 1. symmetry excavates 2. piece simultaneously, respectively from 101 axles, 106 axles " fan-shaped " inner arc mode to 3. piece move back and dig, when being excavated to the 3. during piece, reduce digging machine quantity, change " fan-shaped " outer arc into and move back and dig the 3. piece, now shoveling speed slows down, guarantee the 3. indwelling time of piece soil, after treating 1. 2. piece bottom slab concreting, then Rapid Excavation is received the end.First 2. 1. excavation the arranged that 4 digging machines start from bight to move back to center position " fan-shaped " inner arc during piece and dug, when " fan-shaped " inner arc peak approaches or slightly surpass next Support Position, stop cutting the earth and start to lift angle brace, angle brace installs rear continuation inner arc and moves back and dig, and changes illustrated steps two modes into and cut the earth after angle brace position foundation pit earth has been dug; When illustrated steps two modes are cut the earth, two digging machine side by side, " fan-shaped " interior camber line moves back and digs, when in shoveling traveling process, inner arc rise h is approximately 1.2 times of support intervals (camber line closest approach surpasses lower road and supports about 1m) stop cutting the earth, tower crane is installed and is supported, and now enclosure wall foot section in both sides is left to wait to cut the earth and played a supporting role.Support installs rear continuation " camber line " inner arc and moves back and dig, and carries out next and cuts the earth, installs the circulation of supporting.The the quantity of digging machine when 3. piece " fan-shaped " outer arc is cut the earth is reduced to 1, and " fan-shaped " outer arc moves back to dig receives soil.After in the dark 3600 square metres of holes of 10m, hole is all excavated and seen the bottom, heave of base amount maximum value is in 50mm, and in hole, the maximum displacement of pit enclosure steel sheet pile is in 60mm, and deformation control of foundation pit obtains ideal.
Step 5, timely block placement sole plate.In hole, cheat piecemeal excavation and see the bottom, block placement sole plate.It is a process of carrying out continuously that the support → again of cutting the earth → add is cut the earth, and according to the setback direction that 1. 2. piece excavation sees the bottom, at any time immediately following building substrate bed course, prepares sole plate construction.Because this engineering foundation structure base slab is thicker, reinforcing bar, the larger construction period of amount of concrete are relatively long, the 1. 2. synchronous " fan-shaped " setback a rate of advance of piece is very fast, for reduce substrate open-assembly time as far as possible, 1. 2. in piece every divide again two to build base plate, make foundation ditch piecemeal open-assembly time further shorten (4 days every fritter construction of bottom plates time), foundation ditch exposed area enters one and dwindles.
Zhong Keng position, this engineering hole cuts the earth, install and support, all build complete when shared 28 days to sole plate, be shorter than at least 40 days of former anticipation, actual measurement foundation pit deformation is all controlled in design allowed band, cheats excavation method foundation pit construction efficiency and safety are greatly improved in visible large area band inner support hole.
Claims (8)
1. under Soft Soil, in large area band inner support hole, cheat an excavation method, it is characterized in that: described excavation method comprises the steps:
Step 1: weak soil in foundation ditch is reinforced, improved its engineering property;
Step 2: the convenient and swift installation of tower crane is set and supports;
Step 3: symmetrical piecemeal synchronously excavates;
Step 4: " fan-shaped " setback is cut the earth, and temple is dug on limit; Described " fan-shaped " setback is cut the earth and is referred to that mouth line of the domatic end of soil excavation becomes " fan-shaped " camber line, backhoe digging machine regression excavation, and at the bottom of backhoe digging machine erect-position, mouth line is " fan-shaped " interior camber line or " fan-shaped " outer camber line relatively;
Step 5: timely block placement sole plate.
2. in large area band inner support hole, cheat excavation method under Soft Soil according to claim 1, it is characterized in that: described step 1 comprise at the bottom of Foundation Pit and weak soil to be dug reinforce, increase soil strength, improve base bottom heave drag and shoveling and put the slope gradient.
3. according to cheating excavation method in large area band inner support hole under Soft Soil described in claim 1 or 2, it is characterized in that: in described step 1, to soil stabilization and improve performance requirement and comprise:
A) for natural moisture content ω ﹤ 50%, natural air space ratio e ﹤ 1.5, osmotic coefficient k > 10
-6cm/s, grogs formation and permeability are suitable for the general weak soil of precipitation, adopt deep-well or light shape well point drainage precipitation method to carry out the fixed soil strength that improves;
B) for natural moisture content ω > 50%, natural air space ratio e > 1.5, osmotic coefficient k < 10
-6cm/s, grogs formation and permeability are unsuitable for the special defects weak soil of precipitation, adopt the stake of deep cement-mixed pile " grid " row of piles to reinforce the interior indigenous method in the end, hole and hole and improve soil strength;
C) after reinforcement of soft soil, soil body engineering property has corresponding raising, after reinforcement of soft soil improves, its moisture content target control is below 40%, cohesion C, the target control of internalfrictionangleφ value are at 30.0kPa with more than 15.0 °, make to cut the earth and put slope proportional control in 1:1, guarantee the disposable substrate design absolute altitude that is excavated to of backhoe digging machine energy;
D) in conjunction with the setting of symmetrical piecemeal in " step 3 ", " cross " high density stabilization zone is set in hole in hole, strengthening bearing capacity of foundation soil, prepares for be unearthed vehicle or digging machine travel; To span centre piecemeal, district reinforces especially, as last foundation ditch receive dirt road road and in digging process as temporary supporting earth dam in the long end bay of space enclosing structure, with finite constraint span centre space enclosing structure, be out of shape.
4. under Soft Soil according to claim 1, in large area band inner support hole, cheat excavation method, it is characterized in that: described step 2 is included in foundation ditch outside tower crane is set, tower crane lifting capacity and effectively lift by crane radius according to tower crane setting position and the selected the longest single-unit weight of standard steel pipe support, be supported to tower crane distance and select; In soft base, the existing engineering pile of tower crane utilization or increase arrange bored pile.
5. under Soft Soil according to claim 1, in large area band inner support hole, cheat excavation method, it is characterized in that: described step 3 comprises carries out refinement piecemeal to hole in large area hole, and piecemeal principle is symmetrical equilibrium, and every fritter area is no more than 900m
2, along with the increase piecemeal area of foundation depth further reduces.
6. in large area band inner support hole, cheat excavation method under Soft Soil according to claim 1 or 5; It is characterized in that, in described step 3, to hole in similar rectangle hole, along the even piecemeal in the long limit of space enclosing structure, first symmetrical synchronous excavating structure minor face two, after treating that piecemeal district, two sole plate is built, excavate piecemeal in long end bay, soil outlet is arranged in long end bay one or both sides again.
7. under Soft Soil according to claim 1, in large area band inner support hole, cheat excavation method, it is characterized in that: described step 4 comprises " fan-shaped " setback shoveling in hole in hole, and temple is dug on limit, and its concrete steps and cooperation method are:
One of: first, from four jiaos of symmetrical " fan-shaped " inner arc excavations of foundation ditch, digging machine is advanced to foundation ditch middle part direction, and interior camber line rise is controlled and is not more than angle brace spacing;
Two: again from both sides minor face to the long end bay of space enclosing structure, direction " fan-shaped " inner arc moves back and digs, and interior camber line rise is controlled and is not more than 1.2 times of support intervals;
Three: after treating piecemeal district, both sides bottom slab concreting, to unearthed direction " fan-shaped " outer arc, move back and dig in long end bay piecemeal soil, complete shoveling work;
Four: backhoe is moved back in shoveling traveling process when in " fan-shaped ", camber line summit approaches or slightly surpasses next Support Position, now not adding support zone enclosure wall inner side still has a certain amount of waiting to cut the earth, suspend and cut the earth, transfer to tower crane lifting standard support, coordinate setback and so forth until support installs, excavation of foundation pit is complete.
8. under Soft Soil according to claim 1, in large area band inner support hole, cheat excavation method, it is characterized in that: described step 5 comprises according to piecemeal excavation sequence builds sole plate in time, in hole, cheat piecemeal see the bottom to sole plate, build the complete duration should be over 7 days, the darker piecemeal area of foundation ditch is larger, and the time should be shorter.
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| CN102979102B (en) * | 2012-12-11 | 2015-04-22 | 同济大学建筑设计研究院(集团)有限公司 | Open-excavation sequential-operation deformation-control design method for deep and large circular foundation ditch in soft soil areas |
| CN103114594B (en) * | 2013-03-06 | 2014-12-17 | 熊楚炎 | Supporting structure of adjacent two foundation trenches and construction method thereof |
| CN103510520A (en) * | 2013-10-09 | 2014-01-15 | 上海市建工设计研究院有限公司 | Sectionalized construction method of deep and large foundation pit |
| CN104947653B (en) * | 2014-03-28 | 2017-06-30 | 中国二十冶集团有限公司 | For the decompression method of vibrator pipe sinking cast-in-place pile construction in saturation mud |
| CN105239581A (en) * | 2015-08-28 | 2016-01-13 | 上海市政工程设计研究总院（集团）有限公司 | Lattice-shaped strengthening method for bottom of foundation pit in soft soil area |
| CN105089063A (en) * | 2015-08-28 | 2015-11-25 | 上海市政工程设计研究总院（集团）有限公司 | Lattice-shaped reinforcing structure used for pit bottom of foundation pit in soft soil area |
| CN105908748B (en) * | 2016-05-31 | 2019-01-22 | 中国建筑第八工程局有限公司 | To the Brace in Deep Footing Groove method for being used to control foundation pit deformation under supporting system |
| CN108343067B (en) * | 2018-02-11 | 2020-02-07 | 宁波市明耀智能科技有限公司 | Method for excavating foundation pit on soft soil with water content of more than 60 percent |
| CN110439048B (en) * | 2019-08-29 | 2024-06-28 | 南京江北新区中心区发展有限公司 | Hydraulic punching cutter suction equipment and method for inner support foundation pit engineering |
| CN110965586B (en) * | 2019-11-25 | 2021-06-29 | 中国十九冶集团有限公司 | Construction method of multi-layer basement structure of municipal road |
| CN112695763A (en) * | 2020-12-28 | 2021-04-23 | 中国水利水电第七工程局有限公司 | Deep sludge stratum foundation pit excavation method |
| CN114707225B (en) * | 2022-04-25 | 2024-05-28 | 中铁城建集团有限公司 | Foundation pit supporting performance evaluation method and device considering water level fluctuation and supporting aging |
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