CN103061224A - Method for thawing and strengthening permafrost foundations by quicklime-sand piles - Google Patents
Method for thawing and strengthening permafrost foundations by quicklime-sand piles Download PDFInfo
- Publication number
- CN103061224A CN103061224A CN2013100294000A CN201310029400A CN103061224A CN 103061224 A CN103061224 A CN 103061224A CN 2013100294000 A CN2013100294000 A CN 2013100294000A CN 201310029400 A CN201310029400 A CN 201310029400A CN 103061224 A CN103061224 A CN 103061224A
- Authority
- CN
- China
- Prior art keywords
- quicklime
- pile
- ground
- soil
- stake
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)
Abstract
The invention relates to a method for thawing and strengthening permafrost foundations by quicklime-sand piles. In road construction, island permafrost under the permafrost foundations is difficult to process, and the permafrost foundations require a long time to thaw and stabilize, if the permafrost is not processed, diseases or certain potential unstable factors certainly can be generated in the operation process of the road. The method for thawing and strengthening the permafrost foundations by the quicklime-sand piles comprises the steps of: previously preparing, drilling holes in the permafrost by revolving or impacting, and filling quicklime and macadam mixed uniformly into the holes to form the piles, wherein the mix proportion by volume of the quicklime to the macadam is in the range between (1:4)-(1:1). The hole forming mode is selected according to soil texture and underground water condition, and the reasonable mix proportion is selected according to the type of the permafrost. The method for thawing and strengthening the permafrost foundations by the quicklime-sand piles is applied to the road foundation strengthening construction of the island permafrost road foundations under the permafrost foundations.
Description
Technical field: the present invention relates to a kind of characteristic of quicklime of utilizing and in frozen soil foundation, carry out the job practices that highway subgrade is built.
Background technology:
For a long time, research stable about subgrade in permafrost soil zone and disease management is both at home and abroad continuing always, effort by numerous experts, scholar has obtained great successes, and the theory and technology level has had large increase, is also accumulating rich experience aspect practice and the production application.By the experimental study to the prospecting of the ever-frozen ground of our province and some relevant problems; recognize that the island-shaped permafrost soil under the protection roadbed is very difficult; and the thaw collapse of ever-frozen ground ground and the stable long time that needs; if ever-frozen ground is not processed; in the operation process of highway, will certainly produce disease or potential certain destabilizing factor; therefore, the ever-frozen ground Ground Treatment Schemes of seeking effective control frozen soil disease and economical rationality is very necessary.
Summary of the invention:
The object of the invention provides a kind of characteristic of utilizing quicklime is carried out highway construction and reinforcing at frozen soil foundation job practices.In conjunction with Permafrost of Heilongjiang Privince feature and distress mechanism thereof, reinforcement mechanism and the scope of application with reference to the treatment of soft foundation scheme, reference lime pile, lime-soil compaction pile, sand-gravel pile, Dense Broken Stone Peg, rammed concrete pile, CFG stake, post hammer develop stake and shallow-layer changes Ground Treatment Schemes commonly used such as filling out rubble, carries out consolidation process for different ever-frozen ground highway section ground.
The object of the present invention is achieved like this:
The short method of reinforcing the ever-frozen ground ground of melting of a kind of quicklime sand-gravel pile, its composition comprises: early-stage preparations, adopt revolution or impact drilling and forming hole in ever-frozen ground, ram in the hole and fill out quicklime and the rubble pile that stirs, the nominal mix proportion scope of quicklime and sandstone is between 1:4 ~ 1:1.Select the pore-forming mode according to soil property and groundwater condition, according to the rational match ratio of the type selecting of ever-frozen ground.
The short method of reinforcing the ever-frozen ground ground of melting of described quicklime sand-gravel pile, the described rammer in the hole filled out quicklime and the sandstone pile that stirs, at first, for melt layer and soft clay frozen crust, during impact holing soil layer around the stake hole is produced very large horizontal extruding force, stake soil squeezes peripherad soil layer, makes that soil layer void ratio around the pile body reduces, compactness increases; Secondly, when hammer ram is rammed the material of body of a pile of inserting in the hole, ram energy and at the bottom of the hole, reach transmission all around by sandstone, native compacted with at the bottom of the hole and around the stake, and having in the frozen soil of some sandstones around clamp-oning is when forming, also form in stake week one with the cementing compacted band of sandstone, increased stake directly; At last, to be conducive to eliminate the compacted and compacted effect of expanding of the suction of ever-frozen ground thaw collapse most, reinforcement effect key to the ever-frozen ground ground is that quicklime suction heat release can make frozen soil all melt in a short time, and frozen soil could be finished consolidation and settlement after only having thawing under the effect of selfweight stress and subsidiary stress, thereby makes ground satisfy the requirement of bearing capacity.
The short method of reinforcing the ever-frozen ground ground of melting of described quicklime sand-gravel pile is all melted in the ever-frozen ground short-term time for making between stake, and evenly compacted, and stake Kong Yi presses equilateral triangle and arranges, the centre distance between the stake hole is preferably 3 ~ 5 times an of bore dia; The diameter of stake is preferably 300 ~ 600mm; The area of quicklime sandstone compaction pile Ground Treatment should be greater than the floor space of structure or roadbed; When adopting Local treatment, to weak thaw collapse and part thaw collapse frozen soil foundation, the every limit of width that exceeds foundation bed should be less than 0.5m; To strong thaw collapse and part thaw collapse frozen soil foundation, every limit should be less than 1.0m; When adopting full wafer to process, exceed the width of foundation bed outer rim, every limit is not less than 2m.
The short method of reinforcing the ever-frozen ground ground of melting of described quicklime sand-gravel pile, described pile should in time be laid sand-gravel cushion and compacting to construction site after processing, and the highway section after the processing should be filling roadbed as early as possible.In time lay sand-gravel cushion and filling roadbed, can not only guarantee pile crown and pile strength, make also that the long period has a constant load on the frozen soil foundation, be conducive to finishing as early as possible of foundation settlement distortion, and can prevent that the pile body expansion from causing upwards swollen pulling out, and avoids weakening the horizontal compacted effect of stake.Quicklime sand-gravel pile construction should be carried out in the middle of roadbed two side direction, so that frozen soil melts in the middle of two side direction under the roadbed, water can be discharged to both sides after being conducive to frozen soil and melting, and is remedying because the settling rate inequality that roadbed both sides base pressure causes in less than the road.
The short method of reinforcing the ever-frozen ground ground of melting of described quicklime sand-gravel pile, described early-stage preparations: at first clear up smooth construction plant, lay sand cushion and roll layout stake position; When surface water was arranged, sand cushion should be higher than the earth's surface water level; Answer cleaning hole internal water accumulation and residue and in time carry out filler before the filler of stake hole; Insert a hole compacting with the filler layering that standard hopper or dumper will mix and stir; When adopting casing pipe hole forming, limit layering filling tamped, sleeve pipe is extracted on the limit; Each hole should be rammed and be filled to underground 10 ~ 30m, and its stake Kong Yiyong top, top course rams envelope.
Beneficial effect:
1. the present invention adopts lime pile, sand-gravel pile and Dense Broken Stone Peg to make up, adopt to impact or the quicklime sand-gravel pile of rotary drilling pore-forming, compacting pile, degenerate serious island-shaped permafrost soil and temperature are higher than-1.0 ℃ linking frozen soil, and to urge to melt consolidation process be effective.
2. the quicklime sand-gravel pile belongs to the semi-rigid stake of low binding strength, pile body has some strength, qu is between 500～1000Kpa for its unconfined compression strength, stake top stress is between 0.4～0.9qu, it is similar to the CFG stake of rigidity shape, it has higher supporting capacity and very little distortion, and this pile body is to utilize abrasion drill or Churn drill drilling and forming hole, in the impact holing process ground local products is given birth to larger horizontal compacted effect; Ram quicklime and the sandstone of inserting in the hole by hammer ram, the closely knit pile body of formation is rammed energy and is transmitted all around to the stake hole by material of body of a pile, to the living certain compacted effect of stake week local products; After pile body formed, the suction exothermic reaction of quicklime, volume expansion made all local products of stake give birth to certain discharging consolidation.Therefore, adopt the quicklime sand-gravel pile can increase substantially ground total bearing capacity and minimizing settling amount.
3. the scope of application is wider, Lime Flyash Pile Method is applicable to process the ground such as saturated cohesive soil, mud, mucky soil, plain fill and miscellaneous fill, owing to the imbibition effect of quicklime, be specially adapted to the reinforcing of recent fill and mud, also can make mud generation deadweight fixed after the quicklime suction; The lime-soil compaction pile method is applicable to process the grounds such as collapsible loess, plain fill and miscellaneous fill; The Dense Broken Stone Peg composite foundation is applicable to the grounds such as compacted loosening sand, silt, plain fill and miscellaneous fill.When take the bearing capacity that improves ground or when strengthening its water stability as main purpose, should select the lime-soil compaction pile method.
The property class of ever-frozen ground ground is like collapsible loess foundation, they all are that the variation owing to external condition has a negative impact in the later stage, ever-frozen ground is because the variation of thermal condition causes the frozen soil thaw collapse, and collapsible loess is to cause the foundation soil saturated yielding because immersion or humidity increase.Ever-frozen ground generally buries darker and thicker, and the quicklime Sand Pile Method just is being applicable to deep layer encryption ground, process the degree of depth and be generally 5-15m, therefore, can be used for the ever-frozen ground ground is processed, thereby the raising bearing capacity of foundation soil reduces the ground compressibilty, thereby can weaken or eliminate to a certain extent the thaw collapse of ever-frozen ground; What is more important, the quicklime hydration is emitted a large amount of heats, ever-frozen ground is melted, so, the ever-frozen ground ground just becomes and is similar to common soft base, and the composition of ever-frozen ground mostly is greatly the weak soils such as saturated cohesive soil, mud, mucky soil, and the discharging consolidation speed of weak soil has been accelerated in the imbibition of quicklime, slow thaw collapse and the differential settlement of ever-frozen ground ground have been avoided, reduced settlement amount after construction, eliminated the ever-frozen ground ground and can not stablize the harmful effect that engineering is caused for a long time.In a word, not high for settlement request, as to have the close consolidation time of pressure (squeezing) of certain preloading densification condition and abundance highway subgrade, it should be very effective adopting quicklime sandstone compaction pile.
4. consolidation effect is good
The quicklime sand-gravel pile is to the reinforcement effect main manifestations of ever-frozen ground ground in the following areas:
A, compacted effect
The ever-frozen ground temperature of our province is all not bery low, most of frozen soils temperature is more than-3 ℃, especially island-shaped permafrost soil, temperature generally is not less than-1.0 ℃, frozen soil mostly is the larger soft clay of void ratio and freezes to form, and its water content is higher, and wherein has a certain amount of water that do not freeze, make it have certain plasticity, mostly be hard plastic-semi-stiff state.Therefore, adopt greater impact can impact device can be in the ever-frozen ground stratum impact holing, proved this point at the percussion drilling of ever-frozen ground prospecting, and hole quality is good in the frozen soil, and the impact of underground water is seldom arranged.Therefore, can develop the method pore-forming with reference to the post hammer for ever-frozen ground.Adopt impact holing, need not outer haul volume, thereby saved the workload of the earthwork, the duration, fugitive rate was high.But for the sand that freezes, gravel, rubble and harder cohesive soil, impact holing is unaccommodated, should adopt mechanical drilling and forming hole.
The compacted effect of quicklime sandstone compaction pile is mainly three parts.At first, for melt layer and soft clay frozen crust, during impact holing soil layer around the stake hole is produced very large horizontal extruding force, stake soil squeezes peripherad soil layer, makes that soil layer void ratio around the pile body reduces, compactness increases; Secondly, when hammer ram is rammed the material of body of a pile of inserting in the hole, ram energy and at the bottom of the hole, reach transmission all around by rubble, with at the bottom of the hole and the stake around native compacted, and there are some rubbles to clamp-on in the frozen soil all around, when forming stake, also form in stake week one with the cementing compacted band of rubble, increased to a certain extent stake directly; At last, be to be conducive to eliminate the compacted and compacted effect of expanding of the suction of ever-frozen ground thaw collapse most, test verified, the 1kg carbonate-free lime is digested to the hydrated lime 0.32kg that can absorb water, become calcium hydroxide, and calcium hydroxide can absorb water still, therefore reduce the water content that frozen soil melts the weak soil that forms.Volume expansion occurs in quicklime after suction, its volume expansion is approximately 0.99 times behind the quicklime slaking, under 50 ~ 100kpa pressure, still can expand nearly 30%, because pilespacing is little, general 0.8 ~ 1.5m, the imbibition of pile body is laterally compacted, be equivalent to the soil layer of thickness 0.5 ~ 1.2m is carried out densification, and suction and expansion be to carry out simultaneously, therefore accelerated the discharging consolidation of weak soil, shortened the compression stabilization time of ground, made the foundation soil after the processing reach in a short time uniform and stable.The subsidiary stress of the load of the filling roadbed generation in earth's surface in frozen soil layer reduces gradually with the increase of the degree of depth, the densification of deep soil layer is fixed slower, therefore the settlement stability of ground just needs the long period, roadbed is difficult to reach stable in short-term, even may produce larger sedimentation in the operation phase of highway.And the quicklime sand-gravel pile can effectively carry out even ground extruding to the deep soil layer, improves its bearing capacity and reduces compressibilty, thereby satisfy upper load to the requirement of the bearing capacity of ground.
B, the short consolidation of melting
The quicklime sand-gravel pile is that to the reinforcement effect key of ever-frozen ground ground quicklime suction heat release can make frozen soil all melt in a short time, and frozen soil could be finished consolidation and settlement after only having thawing under the effect of selfweight stress and subsidiary stress, thereby makes ground satisfy the requirement of bearing capacity.
As everyone knows, quicklime in soil with the water in the form absorbent earth of compound, its reaction equation is: CaO+H2O → Ca (OH) 2+65.31kJ/kg, and the 1kg calcium oxide can produce the heat of 65.31kJ when aquation, and general stratum pile temperature can reach 200-300 ℃.Because heating causes the moisture evaporation, natural moisture content is reduced, be conducive to the earth consolidation dehydration, and impel some chemical reaction to form, such as the formation of hydrated calcium silicate.Consider to adopt the quicklime sand-gravel pile that ever-frozen ground is urged to melt reinforcing, utilize just this characteristic of quicklime suction heat release, in frozen soil layer, set up equally distributed pyrotoxin, impel frozen soil all to melt fast, thereby ground can be stablized as early as possible.
In the ever-frozen ground stratum, because drilling construction disturbance and material of body of a pile have certain initial temperature (warm season construction), make the frozen soil of a hole perisporium produce slight the thawing, the moisture of quicklime in just can absorbent earth reacts and emits heat, impel frozen soil further to melt, melt the compacted and draining of soil because the quicklime reaction volume expands to make simultaneously, ever-frozen ground is all melted.
300mm is directly adopted in the stake of quicklime sand-gravel pile, pile center is apart from 1m, the employing triangle lays out pile, mix and stir with quicklime and the graded broken stone volume ratio by 3:7, the ever-frozen ground temperature is assumed to-1.5 ℃, water content is that 30%～130%(comprises that how freezing native major part contains the water content of native ice sheet), and the water freeze all Cheng Bing in the supposition frozen soil.Can draw by the estimation to the maximum that recepts the caloric, soil layer (mud and mucky soil) that water content is larger, the quicklime aquation liberated heat in the quicklime sand-gravel pile can all melt temperature for-1.5 ℃ of ever-frozen ground and elevate the temperature to more than 0 ℃ fully.Be higher than 130% the native ice sheet that contains for water content, by increasing the stake footpath or increasing the content of quicklime, it is all melted and elevate the temperature to more than 0 ℃.Because various indexs all are that relatively safety adopts in calculating, and the ice of having considered 0 ℃ become 0 ℃ water institute calorific requirement, and do not count in calculating that the warm season pile body imports underground heat and surface water infiltrates the heat that the stake hole is brought into, therefore, temperature can be higher after in fact ever-frozen ground melted.So, adopting the quicklime sand-gravel pile, degenerate serious island-shaped permafrost soil and temperature are higher than-1.5 ℃ linking frozen soil, and urge to melt processing be effective.
C, chemical consolidation effect
Ca (OH) 2 and the CO2 in the soil that the reaction of quicklime aquation produces generate calcium carbonate, make the rubble in the pile body cemented together, formation has the pile body of some strength and water stability, compressive strength qu is between 500～1000Kpa, make the quicklime sand-gravel pile have higher supporting capacity and very little distortion, and guaranteeing that stake is long when larger, a full stake long hair is waved effect, takes full advantage of soil to collateral resistance and the end resistance of stake.The Ca of hydrated lime
2+
Sodium ion is replaced in ion and the weak soil, improved the character of inter-pile soil, and at crust layer that intensity is very high of pile body top layer formation, duricrust soil is so that the pile body area increases, the stake footpath increases thick, frictional resistance between the soil is increased, duricrust soil and pile body sink jointly, guarantee that stake and inter-pile soil can act synergistically the shared upper load better; On the other hand,, distortion higher when the bearing course at pile end bearing capacity hour because inter-pile soil produces larger negative friction, weakens the ever-frozen ground sedimentation of thawing, reduced to a certain extent the thaw collapse amount of ever-frozen ground between stake.In addition, Ca
2+
Ion produces the flocculation reaction effect with the weak soil particle under the effect of water, this course of reaction makes the weak soil particle subtract book in conjunction with water film thickness, the Plasticity Decreasing of soil, and the adhesion stress between grogs increases, and soil strength and water stability are improved.At last, active silica-alumina mineral in hydrated lime and the clay particle further produce chemical action lentamente, absorb again the moisture in the hydrated lime in the process, form crystallization and generate aluminate and hydrated calcium silicate, changed the structure of clay, this course of reaction will last for several years, and be that lime is to the late-acting of bury.
D, reinforced action
When the ever-frozen ground stratum is processed, quicklime sand-gravel pile General Requirements runs through whole ever-frozen ground layer or stake end and enters not in thaw collapse or the weak thaw collapse stratum, pile body is as vertical reinforcing body, under load action, mainly play stress and concentrate effect, thereby the pressure of inter-pile soil burden is reduced relatively, compare with former natural ground, the bearing capacity of composite foundation improves, settling amount reduces.Owing to reinforced action and the part metathesis of quicklime sand-gravel pile, increased the shear strength of foundation soil, improved the Against Sliding Stability ability of ground.In addition, pile body is pressed in (squeezing) close process in the frozen soil thawing and has been played certain drainage, not only shortened the horizontal permeation path of weak soil pore water, material of body of a pile in the soft foundation can also be absorbed remaining moisture discharges downward or upward, accelerate the discharging consolidation of weak soil, thereby increase the intensity of foundation soil, improve the bearing capacity of soft base.
The specific embodiment:
Embodiment 1:
The short method of reinforcing the ever-frozen ground ground of melting of a kind of quicklime sand-gravel pile, its composition comprises: early-stage preparations, adopt the post hammer to develop method soil compaction pore-forming in ever-frozen ground, ram in the hole and fill out quicklime and the rubble pile that stirs, the nominal mix proportion scope of quicklime and rubble should be between 1:4 ~ 1:1.Select the pore-forming mode according to soil property and groundwater condition, according to the rational match ratio of the type selecting of ever-frozen ground.
Embodiment 2:
The short method of reinforcing the ever-frozen ground ground of melting of embodiment 1 described quicklime sand-gravel pile, the described rammer in the hole filled out quicklime and the rubble pile that stirs, at first, for melt layer and soft clay frozen crust, during impact holing soil layer around the stake hole is produced very large horizontal extruding force, stake soil squeezes peripherad soil layer, makes that soil layer void ratio around the pile body reduces, compactness increases; Secondly, when hammer ram is rammed the material of body of a pile of inserting in the hole, ram energy and at the bottom of the hole, reach transmission all around by sandstone, native compacted with at the bottom of the hole and around the stake, and having in the frozen soil of some sandstones around clamp-oning is when forming, also form in stake week one with the cementing compacted band of sandstone, increased stake directly; At last, to be conducive to eliminate the compacted and compacted effect of expanding of the suction of ever-frozen ground thaw collapse most, reinforcement effect key to the ever-frozen ground ground is that quicklime suction heat release can make frozen soil all melt in a short time, and frozen soil could be finished consolidation and settlement after only having thawing under the effect of selfweight stress and subsidiary stress, thereby makes ground satisfy the requirement of bearing capacity.
Embodiment 3:
The short method of reinforcing the ever-frozen ground ground of melting of embodiment 1 or 2 described quicklime sand-gravel piles, described pile bore distribution method, all melt in the ever-frozen ground short-term time for making between stake, and evenly compacted, stake Kong Yi presses equilateral triangle and arranges, the centre distance between the stake hole is preferably 3 ~ 5 times an of bore dia; The diameter of stake is preferably 300 ~ 600mm; The area of quicklime sandstone compaction pile Ground Treatment should be greater than the area of roadbed bottom surface; When adopting Local treatment, to weak thaw collapse and part thaw collapse frozen soil foundation, the every limit of width that exceeds foundation bed should be less than 0.5m; To strong thaw collapse and part thaw collapse frozen soil foundation, every limit should be less than 1.0m; When adopting full wafer to process, exceed the width of foundation bed outer rim, every limit is not less than 2m.
Embodiment 4:
The short method of reinforcing the ever-frozen ground ground of melting of the described quicklime sand-gravel pile of one of the above embodiments, process after the described pile and should in time lay sand-gravel cushion and compacting to construction site, highway section after the processing should be filling roadbed as early as possible, in time lay sand-gravel cushion and filling roadbed, can not only guarantee pile crown and pile strength, make also that the long period has a constant load on the ground of frozen soil highway section, be conducive to finishing as early as possible of foundation settlement distortion, and can prevent that the pile body expansion from causing upwards swollen pulling out, avoid weakening the horizontal compacted effect of stake, the construction of quicklime sand-gravel pile should be carried out in the middle of roadbed two side direction, so that frozen soil melts in the middle of two side direction under the roadbed, water can be discharged to both sides after being conducive to frozen soil and melting, and is remedying because the settling rate inequality that roadbed both sides base pressure causes in less than the road.
Embodiment 5:
The short method of reinforcing the ever-frozen ground ground of melting of the described quicklime sand-gravel pile of one of the above embodiments, described early-stage preparations: at first clear up smooth construction plant, lay sand cushion and roll layout stake position; When surface water was arranged, sand cushion should be higher than the earth's surface water level; Answer cleaning hole internal water accumulation and residue and in time carry out filler before the filler of stake hole; Insert a hole compacting with the filler layering that standard hopper or dumper will mix and stir; When adopting casing pipe hole forming, limit layering filling tamped, sleeve pipe is extracted on the limit; Each hole should be rammed and be filled to underground 10 ~ 30m, and its stake Kong Yiyong top, top course rams envelope.
Embodiment 6:
The short method of reinforcing the ever-frozen ground ground of melting of the described quicklime sand-gravel pile of one of the above embodiments:
Pilespacing should according to the Bearing Capacity of Composite Foundation of designing requirement, the factors such as place ground soil nature, construction technology of processing determine, all melt in the ever-frozen ground short-term time for making between stake, and evenly compacted, stake Kong Yi presses equilateral triangle and arranges, the centre distance s of stake between the hole can be 3 ~ 5 times an of bore dia.The diameter of stake is preferably 300 ~ 600mm, can determine according to design and selected hole forming method.Stake footpath commonly used is 300 ~ 500mm.The hammer ram of selecting should directly adapt with stake.
The area of quicklime sandstone compaction pile Ground Treatment should be greater than the area of roadbed bottom surface.When adopting Local treatment, to weak thaw collapse and part thaw collapse frozen soil foundation, the every limit of width that exceeds foundation bed should be less than 0.5m; To strong thaw collapse and part thaw collapse frozen soil foundation, every limit should be less than 1.0m.When adopting full wafer to process, exceed the width of foundation bed outer rim, every limit should not be less than 2m.
The degree of depth of quicklime sandstone compaction pile Ground Treatment, should determine according to thickness and soil property situation, engine request and the composite factors such as pore-forming and tamping apparatus of ever-frozen ground layer, when the buried depth of ever-frozen ground layer thickness and relative hard formation is little, should determine by relative hard formation buried depth and ever-frozen ground layer thickness, the stake end is penetrated in the hardpan that the ever-frozen ground layer enters thawing; When the ever-frozen ground layer thickness is larger, the stake end is entered not in thaw collapse or the weak thaw collapse stratum, and should estimate ever-frozen ground layer deflection, the distortion permissible value of press roadbed is definite.
The characteristic load bearing capacity of quicklime sandstone compaction pile composite foundation should be determined by on-the-spot single pile or many pile composite foundations load test.The characteristic load bearing capacity of quicklime sandstone compaction pile composite foundation should not be greater than 2.0 times before processing, and should not be greater than 250kPa.Also can estimate by following formula during preliminary design:
fspk=mRa/Ap+?(1-m)?fsk
In the formula: the inter-pile soil bearing capacity reducing coefficient should be pressed the regional experience value, and is desirable 0.75 ~ 0.95 during such as rawness, gets large value when natural foundation bearing capacity is higher; Fspk is Bearing Capacity of Composite Foundation characteristic value (kPa) after reinforcing; Fsk also should press the regional experience value, desirable natural foundation bearing capacity characteristic value fak during such as rawness for inter-pile soil characteristic load bearing capacity (kPa) after reinforcing; Ap is the sectional area of stake; M is area replacement ratio; Vertical bearing capacity of single pile characteristic value Ra gets half of ultimate bearing capacity of single pile when adopting the Single Pile Load load test, also can estimate by following formula during preliminary design:
Ra=μ∑qsili+qpAP
In the formula: μ is the girth (m) of stake; N is the soil layer number of dividing in the long scope of stake; Be collateral resistance, the end resistance characteristic value (kpa) of stake side i layer soil, can determine by relevant specification; Li is the thickness (m) of stake side i layer soil.More than be that for pile body itself, its shape body intensity also satisfies the requirement of the determined bearing capacity of single pile of following formula according to the bearing capacity of single pile of the resistance calculating of soil, press the following formula checking computations:
fcu≧3Ra/AP
In the formula: fcu is 28 days compressive strength average (kpa) of pile body compound test block (length of side 150mm cube) standard curing.
The distortion of quicklime sandstone compaction pile composite foundation is calculated, and should meet (GB50007) pertinent regulations of existing national standard " Code for design of building ", and wherein the modulus of compressibility of composite earth layer can adopt the modulus of deformation of load test to replace.The distortion of composite foundation comprises the distortion of stake and inter-pile soil and the lower sleeping soil layer that is untreated thereof.Because the distortion of ever-frozen ground ground mainly is the distortion of the weak soil of formation after melting between stake.For the how freezing soil of weak thaw collapse and the ice-rich permafrost of thaw collapse, by melt and compacted after, the physico-mechanical properties of inter-pile soil obviously improves, namely the dry density of soil increases, compressibilty reduces, bearing capacity improves, the thaw collapse of ever-frozen ground is eliminated by major part, therefore the distortion of inter-pile soil (composite earth layer) can not calculated; But to full freezing soil and contain native ice sheet and should calculate the distortion of processing soil layer and whether satisfy roadbed to the requirement of settling amount; If can not satisfy, can consider the frozen soil under the roadbed is melted the further consolidation process of weak soil that forms.
Filler in the stake hole should determine that according to the purpose of engine request or Ground Treatment the compacting quality of pile body should be used the control of mean pressure real coefficient.Material of body of a pile is answered back-filling in layers, compaction in layers, and the mean pressure real coefficient value of pile body all should be not little by 0.96.The consumption of quicklime and the particle diameter of sandstone form and should determine according to laboratory test, and the nominal mix proportion scope of quicklime and sandstone should be between 1:4 ~ 1:1.Ever-frozen ground for the weak soils such as mud, mucky soil form can suitably increase the quicklime consumption, and the quicklime consumption is unsuitable excessive near the stake top.When mixing gypsum and cement, addition content is 3%～10% of quicklime weight.
Amount of filler in the quicklime sandstone compaction pile stake hole should be determined by field trial, can multiply by fullness coefficient by design stake pore volume during estimation and determine desirable 1.2 ~ 1.4.As the middle-shallow layer seasonally thaw layer of constructing is when thicker, and the earth's surface may produce or the protuberance phenomenon, and then filler quantity should be increased and decreased according to site specific.
Curing compound quicklime in the material of body of a pile should adopt calcium lime powder, and the content of free calcium oxide should not be lower than 70%, and slaked lime (hydrated lime) content should not surpass 15%.Aggregate adopts the hard materials such as graded broken stone, graded sand and a small amount of aggregate chips, can determine by laboratory test the optimum gradation of rubble.Calcium lime powder should keep away from moisture and drench with rain before use, and the water content of rubble, sand and aggregate chips should be too not large, and mud content must not be greater than 5%, and the maximum particle diameter of rubble should not be greater than 50mm.
The sand-gravel cushion that a layer thickness is 300 ~ 500mm should be laid in quicklime sandstone compaction pile top, and its coefficient of consolidation should be less than 0.96.Mattress layer by the discrete materials such as graded sand and stone, coarse sand, rubble form has following several effect in the ever-frozen ground composite foundation behind short melting:
1) guarantees stake, native shared load.
Mattress layer be set to composite foundation provides stake behind load-bearing the condition of thrusting, to guarantee that inter-pile soil participates in work all the time.Make stake, the stressed normal value that is always of soil.When the thickness of mattress layer was 30cm, the loading sharing of stake soil was less, had given full play to the supporting capacity of inter-pile soil, had reduced the stress on stake top, avoided top stress too to concentrate and make the pile body fracture, buckle and pile crown crushed.
2) adjust stake, native horizontal loading share ratio
When basic Under Lateral Loading, mattress thickness is larger, and Horizontal Displacement is less, i.e. it is less that the horizontal loading that is subjected to is pushed up in stake.Test shows, when mattress thickness is not less than 10cm, pile body can run-off the straight and level fracture, make the stake ability of in composite foundation, can not losing the job.
Embodiment 7:
The quicklime sand-gravel pile in ever-frozen ground highway section is processed construction, should arrange according to the construction speed of the roadbed earthwork.The job practices of quicklime sandstone compaction pile can adopt revolution or ballistic method drilling and forming hole in ever-frozen ground, then rams in the hole and fills out quicklime and the sandstone pile that stirs.Technique is comparatively simple, but determines construction technology, selects hole forming method, sequence of construction, should note following requirement when ramming filler in the hole.
1 pore-forming technique
Hole forming method has the methods such as immersed tube (hammering, vibration), impact, rotary drilling pore-forming, but certain limitation is arranged, as impacting and the hammer hidden pipe pore-forming, in closely knit ever-frozen ground, creep into difficulty, rotary drilling efficient in freezing the cohesive soil stratum is not high, therefore, should consider designing requirement, pore-forming equipment or hole forming method, on-the-spot soil property and on the factors such as impact of surrounding environment, select immersed tube (vibration, hammering) or the method pore-formings such as impact, rotary drilling.
In construction pore-creating or the tube drawing process, stake hole (or stake top) upper soil horizon there is certain loosening effect, therefore, should be according to the pore-forming equipment of selecting and job practices before the construction, certain thickness loosening soil layer is reserved in consideration in the place, after pore-forming and a stake hole backfilling compaction finish it is excavated or process by design code.
2 are reinforced the foundation soil water content
The water content of plan Ground Treatment soil is compacted most important to drilling construction and inter-pile soil, especially the seasonally thaw layer on frozen soil top.Engineering practice shows, when the water content of natural soil less than 12% the time, soil is hardened condition, compaction is very difficult, and equipment easily damages; When the water content of natural soil is equal to or greater than 24%, saturation ratio is greater than 65% the time, and the stake hole may necking down, and the soil around the stake hole is protuberance easily, compacted weak effect; When the water content of natural soil approached optimum (or plastic limit) water content, drilling construction speed was fast, inter-pile soil compacted effective.Therefore, in pore forming process, should consider to adopt sleeve pipe and other retaining wall schemes according to the water content of intending Ground Treatment soil and hole quality.
3 pore-formings and backfilling compaction
Backfilling compaction in pore-forming and the hole should meet the following requirements.
(1) sequence of construction of the backfilling compaction in pore-forming and the hole is processed full wafer, should from outside (both sides) inwards (centre) carry out, to larger paragraph, can take the segmentation worker.
(2) in the hole before the filler, answer sediment at the bottom of cleaning hole internal water accumulation and the hole, should tamp at the bottom of the hole in case of necessity, and should survey sample diameter, the degree of depth and the verticality in a hole.
(3) perpendicularity deviation in stake hole should be greater than 1.5%.
(4) deviation of stake central point of hole should not surpass 5% of pilespacing design load;
(5) through after the assay was approved, by designing requirement, people's filler is filled out in layering in the hole, and answers compaction in layers to design elevation or earth's surface.
Before laying sand-gravel cushion in addition, the loosening soil layer more than the stake top mark height should be excavated or rams (pressure) closely knit.
Claims (5)
1. a quicklime sand-gravel pile urgees to melt the method for reinforcing the ever-frozen ground ground, its composition comprises: early-stage preparations, it is characterized in that: adopt revolution or impact drilling and forming hole in ever-frozen ground, ram in the hole and fill out quicklime and the rubble pile that stirs, the nominal mix proportion scope of quicklime and sandstone is between 1:4 ~ 1:1, select the pore-forming mode according to soil property and groundwater condition, according to the rational match ratio of the type selecting of ever-frozen ground.
2. quicklime sand-gravel pile according to claim 1 urgees to melt the method for reinforcing the ever-frozen ground ground, it is characterized in that: the described rammer in the hole filled out quicklime and the sandstone pile that stirs, at first, for melt layer and soft clay frozen crust, during impact holing soil layer around the stake hole is produced very large horizontal extruding force, stake soil squeezes peripherad soil layer, makes that soil layer void ratio around the pile body reduces, compactness increases; Secondly, when hammer ram is rammed the material of body of a pile of inserting in the hole, ram energy and at the bottom of the hole, reach transmission all around by sandstone, native compacted with at the bottom of the hole and around the stake, and having in the frozen soil of some sandstones around clamp-oning is when forming, also form in stake week one with the cementing compacted band of sandstone, increased stake directly; At last, to be conducive to eliminate the compacted and compacted effect of expanding of the suction of ever-frozen ground thaw collapse most, reinforcement effect key to the ever-frozen ground ground is that quicklime suction heat release can make frozen soil all melt in a short time, and frozen soil could be finished consolidation and settlement after only having thawing under the effect of selfweight stress and subsidiary stress, thereby makes ground satisfy the requirement of bearing capacity.
3. quicklime sand-gravel pile according to claim 1 and 2 urgees to melt the method for reinforcing the ever-frozen ground ground, it is characterized in that: all melt in the ever-frozen ground short-term time for making between stake, and evenly compacted, stake Kong Yi presses equilateral triangle and arranges, the centre distance between the stake hole is preferably 3 ~ 5 times an of bore dia; The diameter of stake is preferably 300 ~ 600mm; The area of quicklime sandstone compaction pile Ground Treatment should be greater than the floor space of structure or roadbed; When adopting Local treatment, to weak thaw collapse and part thaw collapse frozen soil foundation, the every limit of width that exceeds foundation bed should be less than 0.5m; To strong thaw collapse and part thaw collapse frozen soil foundation, every limit should be less than 1.0m; When adopting full wafer to process, exceed the width of foundation bed outer rim, every limit is not less than 2m.
4. according to claim 1 and 2 or the short method of reinforcing the ever-frozen ground ground of melting of 3 described quicklime sand-gravel piles, it is characterized in that: after described pile is processed, should in time lay sand-gravel cushion and compacting to construction site, highway section after the processing should be filling roadbed as early as possible, in time lay sand-gravel cushion and filling roadbed, can not only guarantee pile crown and pile strength, make also that the long period has a constant load on the frozen soil foundation, be conducive to finishing as early as possible of foundation settlement distortion, and can prevent that the pile body expansion from causing upwards swollen pulling out, avoid weakening the horizontal compacted effect of stake, the construction of quicklime sand-gravel pile should be carried out in the middle of roadbed two side direction, so that frozen soil melts in the middle of two side direction under the roadbed, water can be discharged to both sides after being conducive to frozen soil and melting, and is remedying because the settling rate inequality that roadbed both sides base pressure causes in less than the road.
5. it is characterized in that: described early-stage preparations: at first clear up smooth construction plant, lay sand cushion and also roll, arrange the stake position according to claim 1 and 2 or the short method of reinforcing the ever-frozen ground ground of melting of 3 or 4 described quicklime sand-gravel piles; When surface water was arranged, sand cushion should be higher than the earth's surface water level; Answer cleaning hole internal water accumulation and residue and in time carry out filler before the filler of stake hole; Insert a hole compacting with the filler layering that standard hopper or dumper will mix and stir; When adopting casing pipe hole forming, limit layering filling tamped, sleeve pipe is extracted on the limit; Each hole should be rammed and be filled to underground 10 ~ 30m, and its stake Kong Yiyong top, top course rams envelope.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2013100294000A CN103061224A (en) | 2013-01-25 | 2013-01-25 | Method for thawing and strengthening permafrost foundations by quicklime-sand piles |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2013100294000A CN103061224A (en) | 2013-01-25 | 2013-01-25 | Method for thawing and strengthening permafrost foundations by quicklime-sand piles |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN103061224A true CN103061224A (en) | 2013-04-24 |
Family
ID=48104093
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2013100294000A Pending CN103061224A (en) | 2013-01-25 | 2013-01-25 | Method for thawing and strengthening permafrost foundations by quicklime-sand piles |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN103061224A (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103850258A (en) * | 2014-03-24 | 2014-06-11 | 北京城建勘测设计研究院有限责任公司 | Natural freezing support method |
| CN107326765A (en) * | 2017-08-25 | 2017-11-07 | 中铁西北科学研究院有限公司 | Handle segregated frozen ground ground lime pile and its construction method |
| CN108978639A (en) * | 2018-08-16 | 2018-12-11 | 中交建冀交高速公路投资发展有限公司 | A kind of powder seif-citing rate stake and its pile making method |
| CN110306393A (en) * | 2019-07-11 | 2019-10-08 | 哈尔滨工业大学 | A kind of involution form high temperature permafrost area reinforcement heat melts a road structure |
| CN111140199A (en) * | 2019-12-25 | 2020-05-12 | 北京正和恒基滨水生态环境治理股份有限公司 | Shaft plugging method |
| CN112609668A (en) * | 2020-12-10 | 2021-04-06 | 西京学院 | Construction method of foundation for eliminating influence of freezing and thawing environment |
| CN115288112A (en) * | 2022-08-17 | 2022-11-04 | 北京市市政一建设工程有限责任公司 | River course soft soil foundation reinforced structure |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1209489A (en) * | 1997-08-22 | 1999-03-03 | 中航勘察设计研究院 | Construction method for composite foundation by tamping expanding piles and compacting soil around piles |
| JP4716474B2 (en) * | 2001-07-13 | 2011-07-06 | 新日鉄エンジニアリング株式会社 | Pile construction method using granulated blast furnace slag |
| CN102864774A (en) * | 2012-10-10 | 2013-01-09 | 江苏南通六建建设集团有限公司 | Shrinkage treatment construction method for composite foundation- lime soil compaction piles |
-
2013
- 2013-01-25 CN CN2013100294000A patent/CN103061224A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1209489A (en) * | 1997-08-22 | 1999-03-03 | 中航勘察设计研究院 | Construction method for composite foundation by tamping expanding piles and compacting soil around piles |
| JP4716474B2 (en) * | 2001-07-13 | 2011-07-06 | 新日鉄エンジニアリング株式会社 | Pile construction method using granulated blast furnace slag |
| CN102864774A (en) * | 2012-10-10 | 2013-01-09 | 江苏南通六建建设集团有限公司 | Shrinkage treatment construction method for composite foundation- lime soil compaction piles |
Non-Patent Citations (3)
| Title |
|---|
| 张盛国等: "石灰碎石桩处理软土地基设计", 《林业建设》 * |
| 李自停: "粘性土地基中石灰碎石桩的加固机制", 《地质灾害与环境保护》 * |
| 王智: "石灰碎石桩加固高液限粉土地基施工技术", 《山西建筑》 * |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103850258A (en) * | 2014-03-24 | 2014-06-11 | 北京城建勘测设计研究院有限责任公司 | Natural freezing support method |
| CN103850258B (en) * | 2014-03-24 | 2016-06-29 | 北京城建勘测设计研究院有限责任公司 | A kind of weather freezing method for protecting support |
| CN107326765A (en) * | 2017-08-25 | 2017-11-07 | 中铁西北科学研究院有限公司 | Handle segregated frozen ground ground lime pile and its construction method |
| CN108978639A (en) * | 2018-08-16 | 2018-12-11 | 中交建冀交高速公路投资发展有限公司 | A kind of powder seif-citing rate stake and its pile making method |
| CN110306393A (en) * | 2019-07-11 | 2019-10-08 | 哈尔滨工业大学 | A kind of involution form high temperature permafrost area reinforcement heat melts a road structure |
| CN111140199A (en) * | 2019-12-25 | 2020-05-12 | 北京正和恒基滨水生态环境治理股份有限公司 | Shaft plugging method |
| CN112609668A (en) * | 2020-12-10 | 2021-04-06 | 西京学院 | Construction method of foundation for eliminating influence of freezing and thawing environment |
| CN115288112A (en) * | 2022-08-17 | 2022-11-04 | 北京市市政一建设工程有限责任公司 | River course soft soil foundation reinforced structure |
| CN115288112B (en) * | 2022-08-17 | 2024-02-23 | 北京市市政一建设工程有限责任公司 | River course weak soil foundation reinforced structure |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN103061224A (en) | Method for thawing and strengthening permafrost foundations by quicklime-sand piles | |
| CN107503257B (en) | One kind being close to mountain high-filled subgrade stabilization and Deformation control structure and construction method | |
| CN101831901B (en) | Shallow poor subsoil composite foundation stabilization treatment method | |
| CN104131546B (en) | A kind of processing method of collapsible loess foundation | |
| CN103074882A (en) | Construction method for reinforcing island-type perennial frozen-soil foundation by adopting gravel piles | |
| CN207109475U (en) | It is close to mountain high-filled subgrade stabilization and Deformation control structure | |
| CN109736291A (en) | One kind owing consolidation and blows on the base of alluvial plain that biological cement is reinforcing road bed and its construction method | |
| CN101634143A (en) | Method for treating spiral oil-extruding filling pile composite foundation in stratum containing soft clay | |
| CN101899828B (en) | Construction method of bagged rammed small-diameter soil-cement pile composite foundation | |
| CN106948340B (en) | A kind of construction method of the Manual excavated pile structure of high polymer grouting protection | |
| CN105569071B (en) | A kind of slip casting under water of cement-based material or mud jacking block ground mass foundation construction | |
| CN105401589B (en) | A kind of GPS for frozen soil and swelled ground area monitors pier and its construction technology | |
| CN104674842B (en) | Solidified earth barricade and constructional method thereof | |
| CN102839683B (en) | Granular pile-permeable concrete stake dual compound foundation and processing method | |
| CN107326765B (en) | Lime pile for treating island-shaped frozen soil foundation and construction method thereof | |
| CN102296591A (en) | Rapid drainage solidifying treatment method of soft soil foundation | |
| CN106836034B (en) | High-fill cover plate culvert flexible load shedding system and construction method | |
| CN106906709A (en) | A kind of construction method of the modified cement earth pile of quick lime | |
| CN103981880A (en) | Treatment method of composite foundation using top-enlarged and bottom-enlarged CFG piles | |
| CN101200902A (en) | Construction method for concrete shaft wall module masonry | |
| CN202787295U (en) | Dispersive pile-permeable concrete pile novel dual compound foundation | |
| CN106337409A (en) | Method for treating peat soil foundation through preloading in combination with salt piles | |
| CN210684656U (en) | Quick lime gravel pile assembly for permafrost foundation fusion promotion and reinforcement | |
| CN109610497A (en) | One kind is regulated and stored pond foundation anti-seepage processing method | |
| CN110439014A (en) | A kind of underground stratiform discharge structure and its construction method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C02 | Deemed withdrawal of patent application after publication (patent law 2001) | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20130424 |