CN213804676U - Soft soil foundation structure - Google Patents
Soft soil foundation structure Download PDFInfo
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- CN213804676U CN213804676U CN202022423990.3U CN202022423990U CN213804676U CN 213804676 U CN213804676 U CN 213804676U CN 202022423990 U CN202022423990 U CN 202022423990U CN 213804676 U CN213804676 U CN 213804676U
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Abstract
The application discloses soft soil foundation structure, including soft soil foundation, foam concrete foundation and road bed, the soft soil foundation is equipped with the slot, the foam concrete foundation is located in the slot, the road bed cover in the upper surface on foam concrete foundation, the weight of road bed the weight that the road bed bore and the weight sum on foam concrete foundation with the soft soil weight that the slot part of soft soil foundation was dug out equals. The utility model provides a soft soil foundation structure can eliminate the additional stress of road bed to soft soil foundation for the road bed does not produce vertical settlement.
Description
Technical Field
The utility model relates to a civil engineering technical field especially relates to a soft soil foundation structure.
Background
Wide soft soil is distributed in coastal areas of China, and the soft soil has the characteristics of high natural water content, large pore ratio, high compressibility, low shear strength and the like. Referring to fig. 1, as for the natural soft soil foundation 101, because the surface 102 has no load, the self-weight stress distribution curve 103 of the soft soil foundation 101 is reasonably distributed, and the soft soil foundation 101 does not generate vertical settlement under the self-weight stress. When a roadbed is constructed in a soft soil area, please refer to fig. 2, the roadbed 203 with a certain height is filled on the surface 202 of the soft soil foundation 201, the self-weight stress distribution curve 204 of the soft soil is distributed as shown in the figure, because the soft soil has high compressibility, under the action of the load of the roadbed 203, additional stress can be generated in the soft soil foundation 201, the additional stress curve 205 is distributed as shown in the figure, the soft soil foundation 201 can generate vertical settlement, and excessive vertical settlement can generate a plurality of adverse effects on the road. Therefore, the soft soil foundation needs to be treated in the design stage, so that the settlement of the treated roadbed is controlled within the standard allowable range.
At present, the methods for treating soft soil subgrade mainly comprise three types: drainage consolidation method, composite foundation method and light embankment method. The drainage consolidation method is characterized in that under the action of the self weight of a road subgrade, pore water in soil is slowly drained by arranging a vertical drainage well (a sand well or a plastic drainage bag and the like), the soft foundation is gradually consolidated, and the soft foundation is settled; along with the gradual dissipation of the hyperstatic pore water pressure of the soil body, the effective stress of the soil body is gradually increased, the shear strength of the foundation is gradually increased, and the settlement is advanced or the settlement rate is increased so as to achieve the purpose of reducing the settlement of the roadbed in the use stage of the roadbed. The composite foundation method is that part of soil body of the natural foundation is enhanced or replaced in the foundation treatment process, or a reinforcement body is arranged in the natural foundation, the natural foundation soil body and the reinforcement body form an artificial foundation which jointly bears the upper load, and cement mixing piles, high-pressure jet grouting piles, prestressed pipe piles and the like are commonly adopted in road engineering to treat the soft foundation so as to achieve the purpose of reducing subgrade settlement; the light embankment method uses light materials such as foam concrete, EPS and the like as roadbed fillers to reduce the self weight of the roadbed, thereby achieving the purpose of reducing settlement. The composite foundation method and the light embankment method can reduce subgrade settlement to a certain degree, but cannot radically eliminate the subgrade settlement, and the subgrade settlement is large especially for deep soft soil foundations (foundations with the soft soil buried depth of 20-40 m).
SUMMERY OF THE UTILITY MODEL
The utility model provides a to the above-mentioned problem, a soft soil foundation structure is proposed, can eliminate the additional stress of road bed to soft soil foundation for the road bed does not produce vertical settlement.
The utility model adopts the following technical scheme: the utility model provides a soft soil foundation structure, including soft soil foundation, foam concrete foundation and road bed, the soft soil foundation is equipped with the slot, the foam concrete foundation is located the ditch inslot, the road bed cover in the upper surface on foam concrete foundation, the weight of road bed the weight that the road bed bore and the weight sum on foam concrete foundation with the soft soil weight that the slot part of soft soil foundation was dug out equals.
In an example of the utility model, the road bed includes foam concrete road bed and lime soil road bed, foam concrete road bed with lime soil road bed cover in proper order from bottom to top in on the foam concrete basis.
In one embodiment of the present invention, the volume weight of the foamed concrete roadbed is not less than 6KN/m3。
In an embodiment of the present invention, the volume weight of the foam concrete foundation is not less than 5KN/m3。
In an embodiment of the present invention, the height of the lime soil roadbed is not less than 1.0 m.
In an example of the present invention, the surface of the foam concrete foundation is coated with a waterproof layer.
In an example of the present invention, the slope ratio of the roadbed is 1: 1.5.
The utility model has the advantages that: the soft soil foundation structure of the utility model digs part of soft soil in the soft soil foundation to form a groove, pours a foam concrete foundation in the groove to replace the digged soft soil, because the foam concrete foundation is made of light materials, when the volumes are the same, the weight of the foam concrete foundation is less than that of the excavated soft soil, then the roadbed is paved on the foam concrete foundation, so that the sum of the weight of the foam concrete foundation, the weight of the roadbed and the weight borne by the roadbed is equal to the weight of soft soil dug out from the groove part, make the soft soil foundation not increase extra weight, the stress that the foam concrete basis bottom surface received equals with same horizontally dead weight stress in the soft soil foundation this moment, and the stress state of soft soil foundation below the foam concrete basis bottom does not change, and the soft soil foundation can not take place to subside, and then the road bed can not produce vertical settlement yet.
Drawings
FIG. 1 is a schematic structural view of a conventional soft soil foundation;
fig. 2 is a schematic structural view of a soft soil foundation after a roadbed is paved in the prior art;
fig. 3 is a schematic view of a soft soil foundation structure according to an embodiment of the present invention.
The figures are numbered: 1. soft soil foundation; 2. a foamed concrete foundation; 3. a roadbed; 31. a foam concrete roadbed; 32. lime soil roadbed; p0The self-weight stress of the soft soil foundation; p is the stress on the bottom surface of the foam concrete foundation; h1The height of the lime soil roadbed; h2The height of the foam concrete roadbed; h3Is the height of the foamed concrete foundation;
101. soft soil foundation; 102. soft soil foundation surface; 103. the self-weight stress distribution curve of the soft soil; 201. soft soil foundation; 202. soft soil foundation surface; 203. a roadbed; 204. the self-weight stress distribution curve of the soft soil; 205. additional stress curves are applied.
Detailed Description
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown.
Please refer to fig. 3, the utility model provides a soft soil foundation 1 structure, including soft soil foundation 1, foam concrete foundation 2 and road bed 3, soft soil foundation 1 is equipped with the slot, and foam concrete foundation 2 locates the ditch inslot, and road bed 3 covers in foam concrete foundation 2's upper surface, and the weight sum of the weight that road bed 3, road bed 3 bore and foam concrete foundation 2 equals with the soft soil weight that the slot part of soft soil foundation 1 was dug out. Dig out partial soft soil in soft soil foundation 1 and form the slot, foam concrete foundation 2 is pour in the slot, in order to replace the soft soil who is dug out, because foam concrete foundation 2 is light material, make when the volume is the same, foam concrete foundation 2's weight will be less than the weight of the soft soil who is dug out, lay road bed 3 on foam concrete foundation 2 again, make soft soil foundation 1 not increase extra weight, the stress that the foam concrete foundation 2 bottom surface received at this moment is equal with the same horizontally dead weight stress in soft soil foundation 1, the stress condition of soft soil foundation 1 below foam concrete foundation 2 bottom does not change, soft soil foundation 1 can not take place to subside, and then road bed 3 can not produce vertical settlement yet.
The foam concrete foundation 2 is a light filler, has good compressive strength, can be used for heavy-load traffic, has good stability, does not have aging phenomenon along with the prolonging of the integral strength, and has long service life. In addition, because the foam concrete contains a large amount of relatively independent closed bubbles and has good integrity and low water absorption rate, the foam concrete has certain water resistance, and the moisture in the soft soil foundation 1 is not easy to enter the foam concrete foundation 2.
The roadbed 3 comprises a foam concrete roadbed 31 and a lime soil roadbed 32, and the foam concrete roadbed 31 and the lime soil roadbed 32 are sequentially covered on the foam concrete foundation 2 from bottom to top. In order to reduce the self weight of the roadbed 3 filler as much as possible, after a foam concrete roadbed 31 with a certain height is filled on the surface of the soft soil foundation 1, a lime roadbed 32 is laid on the foam concrete roadbed 31, so that the sum of the weight of the foam concrete foundation 2, the weight of the foam concrete roadbed 31, the weight of the lime soil roadbed 32 and the weight borne by the roadbed 3 is equal to the weight of soft soil dug out of the trench part. Compared with the roadbed filling of the soil-stone mixture, the foamed concrete roadbed 31 has light dead weight, good integrity and ageing resistance, and can greatly prolong the service life of the pavement. The limestone soil roadbed 32 is made of limestone soil, and the roadbed made of the limestone soil has high strength and good integrity compared with an earth-rock mixture roadbed filler, can greatly prolong the service life of the pavement, and has low manufacturing cost and good economical efficiency.
The volume weight of the foam concrete roadbed 31 is not less than 6KN/m3. The foam concrete roadbed 31 mainly bears the load of an upper roadbed and the load of an automobile and needs to have certain strength.
The volume weight of the foam concrete foundation 2 is not less than 5KN/m3. The foam concrete is a light filler, the foam concrete foundation 2 is used as a filling material for soft soil, the characteristic of light weight of the foam concrete foundation is fully exerted, and the relatively low dry volume weight is selected as much as possible to reduce the self weight of the filler, so that the aim of reducing the additional stress of the foundation is fulfilled. The volume weights of the foam concrete foundation 2 and the foam concrete roadbed 31 are dry volume weights, and the compressive strengths of the foam concrete foundation 2 and the foam concrete roadbed 31 are not less than 0.6 MPa.
The height of the lime soil roadbed 32 is not less than 1.0m, so that the overall structural strength of the roadbed 3 can be ensured. The height of the lime soil subgrade 32 can be adjusted correspondingly according to the actual conditions of the project. Wherein the volume weight of the lime soil roadbed 32 is 18-20KN/m3。
The surface of the foam concrete foundation 2 is covered with a waterproof layer (not shown in the figure), and water in the soft soil can be further prevented from entering the foam concrete foundation 2 through the waterproof layer. The waterproof layer can be macromolecular material such as polytetrafluoroethylene, or modified asphalt etc. and the index of waterproof layer satisfies relevant standard regulation can, the embodiment of the utility model discloses a do not do specifically to this and restrict.
The slope rate of the roadbed 3 is 1: 1.5. The overall cross section of the roadbed 3 is trapezoidal; the cross section of the foam concrete foundation 2 is rectangular, the design is reasonable, and the structure has stability. The slope rate of the roadbed 3 is 1:1.5, and the foamed concrete roadbed 31 and the lime soil roadbed 32 can be well protected and supported.
The construction method of the soft soil foundation structure comprises the following specific steps:
the method comprises the following steps: construction preparation, namely designing a structure of a foam concrete foundation 2 according to the soft soil foundation 1;
step two: digging part of soft soil in the soft soil foundation 1 to form a groove for pouring the foam concrete foundation 2;
step three: pouring the foam concrete foundation 2 in the groove to enable the outer wall of the foam concrete foundation 2 to be attached to the soft soil foundation 1;
step four: preparing a filler of the foam concrete roadbed 31, and pouring foam concrete on the upper surface of the foam concrete foundation 2 to form the foam concrete roadbed 31;
step five: preparing the filler of the lime soil roadbed 32, paving the lime soil filler on the upper surface of the foam concrete roadbed 31 to form the lime soil roadbed 32, and compacting the lime soil roadbed 32.
The filler of the lime soil roadbed 32 in the fifth step can adopt lime soil prepared by mixing lime with soft soil dug in the second step. The dug soft soil is used as a raw material, so that the aim of comprehensively utilizing waste soil can be fulfilled, the environment is protected, and the construction cost is reduced; meanwhile, the mountain body excavation caused by the purchase of the fillers of the lime soil roadbed 32 can be avoided, and mineral resources are saved. Lime soil roadbed 32 can also adopt lime soil, or the local materials such as the slag of dying of common use are filled, the embodiment of the utility model discloses a do not do specifically to this and restrict.
Wherein, when the foam concrete filler used in the foam concrete foundation 2 in the third step is the same as that used in the foam concrete roadbed 31 in the fourth step, an integrally formed structure can be adopted. When a waterproof layer is required to be coated on the surface of the foam concrete foundation 2, the waterproof layer can be firstly coated in the groove of the soft soil foundation 1, and then the foam concrete foundation 2 is poured in the groove coated with the waterproof layer.
In one embodiment, the structural design of the foam concrete foundation 3 is as follows:
at present, a certain section of a certain expressway is selected for carrying out the structural design of the soft soil foundation 1. The design is suitable for a bidirectional six-lane highway, the design speed is 100km/h, the roadbed width is 33.5m, the filling height of the roadbed at the road section is different from 3.96m to 4.31m, the average filling height is about 4.0m, and the side slopes on the two sides of the roadbed are all 1:1.5, the roadbed cross slope is 2 percent, and the designed load is a highway-I level.
(1) Detecting engineering geology
The foundation of this section is located the area of the plain of area of sea area, and the relief is wide and flat. Drilling to reveal clay on the surface layer under the foundation, wherein the clay is gray yellow and plastic and has the thickness of 0-1.6 m; the lower layer is silt, gray, fluid plastic and high in compressibility and has the thickness of about 14 m; the specific parameters of the underburden sludge, gravel and clay are shown in the following table 1:
TABLE 1 geological section of foundation and each layer of geological foundation parameters
(2) Foamed concrete foundation plane dimension planning
Referring to fig. 3, the roadbed 3 has a height H (H ═ H)1+H2) Wherein the height of the limestone soil subgrade 32 is H1Filling with lime soil; the height of the foam concrete roadbed 31 is H2Adopting foam concrete for filling; the depth of the foam concrete foundation 2 is H3. The width of the roadbed top is WTThe width of the foam concrete foundation 2 is WBThe length of the foam concrete foundation 2 is the same as that of the roadbed.
(3) Substrate stress calculation
3.1 base stress P caused by vehicle load1
According to the general Specification for designing bridges and culverts of highways, the bidirectional six-lane concrete foundation is designed, the top width of a lime soil roadbed 32 is 33.5m, the filling height H of the roadbed 3 is 4m, the transverse arrangement of vehicle loads is considered according to eight heavy vehicles, and the stress on the base of a foam concrete foundation 2 is realized under the action of the vehicle loads:
P1＝∑G/A＝8×550/[(33.5+3×H))×(13+2×H)×TAN(30°))]
＝8×550/[(33.5+3×4)×(13+2×(4×TAN(30°))]
＝5.49KN/m2
3.2 base stress P caused by roadbed loading2
The top width of the foam concrete roadbed 31 is 33.5m, and the slope rate of the foam concrete roadbed 31 side slope is 1:1.5, 32 fill height H of lime soil roadbed11.0m, foam concrete road base 31 filling height H23.0m, the width of the bottom of the foam concrete roadbed 31 is 3 (H)1+H2). The limestone soil roadbed 32 is filled with limestone soil with volume weightγ1Is 18KN/m3(ii) a The foam concrete roadbed 31 filler is foam concrete with the volume weight gamma2Is 6KN/m3。
∑G＝(33.5+(33.5+3H1))×(H1/2)×γ1+((33.5+3H1)+(33.5+3(H1+H2))×(H2/2)×γ2
＝(33.5+(33.5+3×1)×(1/2)*18+((33.5+3×1)+(33.5+3×(1+3)))×(3/2)×6＝630+738＝1368KN
P2＝∑G/A＝∑G/[33.5+3×(H1+H2)]＝1368/(33.5+3×(1+3))＝30KN/m2
3.3 base stress P caused by the load of the foam concrete foundation3
The foam concrete foundation 2 has a transverse width of 33.5m +3 × (H)1+H2) The base stress was calculated as 1m in the longitudinal direction. The height of the foam concrete foundation 2 is H3Of density gamma thereof3Is 6KN/m3。
P3＝G/A＝γ3H3＝6H3
3.4 Soft soil foundation 1 self-weight stress P0
The soft soil foundation 1 of the foam concrete foundation 2 has two layers, the first layer of soil is clay, the thickness of the soil layer is 1.6m, and the natural wet density is 19.7KN/m3The second layer is sludge, the thickness of the soil layer is 13.8m, and the natural wet density is 16.5KN/m3。
P0＝γh＝1.6×19.7+(H3-1.6)×16.5＝16.5H3+5.12
(4) Foam concrete foundation height calculation
In order to prevent the base of the foam concrete foundation 2 from generating additional stress, namely the self-weight stress of the soft soil foundation 1 is equal to the base stress generated by the upper load, wherein the stress P ═ P received by the bottom surface of the foam concrete foundation 21+P2+P3I.e. by
P0＝P1+P2+P3
16.5H3+5.12＝5.49+30+6H3
H3＝2.89m
(5) Different roadbed filling heights correspond to the heights of the foam concrete foundation
Through calculation and analysis, when the base of the foam concrete foundation 2 does not generate additional stress, the width of the foam concrete pavement 31 and the natural wet density of sludge have small influence on the burial depth of the foam concrete foundation 2, the burial depth of the foam concrete foundation 2 is mainly influenced by the filling heights of the foam concrete pavement 31 and the lime soil pavement 32, and a corresponding parameter table of the foam concrete foundation 2 is determined according to different pavement filling heights by calculation according to the method, and is detailed in the table 2.
TABLE 2 relationship of subgrade fill height to foam concrete foundation
The above only is the preferred embodiment of the present invention, not therefore the limit the patent protection scope of the present invention, all applications the equivalent structure transformation made by the contents of the specification and the drawings of the present invention is directly or indirectly applied to other related technical fields, and all the same principles are included in the protection scope of the present invention.
Claims (7)
1. The utility model provides a soft soil foundation structure, its characterized in that, includes soft soil foundation, foam concrete foundation and road bed, the soft soil foundation is equipped with the slot, the foam concrete foundation is located in the slot, the road bed cover in the upper surface on foam concrete foundation, the weight of road bed the weight that the road bed bore and the weight sum on foam concrete foundation with the soft soil weight that the slot part of soft soil foundation was dug out equals.
2. A soft soil foundation structure as claimed in claim 1, wherein said roadbed includes a foamed concrete roadbed and a lime soil roadbed, said foamed concrete roadbed and said lime soil roadbed being overlaid in sequence from bottom to top on said foamed concrete roadbed.
3. A soft soil foundation structure as claimed in claim 2, wherein the bulk density of the foamed concrete subgrade is not less than 6KN/m3。
4. A soft soil foundation structure as claimed in claim 1, wherein the foam concrete foundation has a bulk density of not less than 5KN/m3。
5. A soft soil foundation structure as claimed in claim 2, wherein the height of the lime soil subgrade is not less than 1.0 m.
6. A soft soil foundation structure as claimed in claim 1, wherein the surface of the foamed concrete foundation is coated with a waterproof layer.
7. A soft soil foundation structure as claimed in claim 1, wherein the slope rate of the subgrade is 1: 1.5.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113897830A (en) * | 2021-08-25 | 2022-01-07 | 浙江交工金筑交通建设有限公司 | Construction method of soft foundation embankment |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113897830A (en) * | 2021-08-25 | 2022-01-07 | 浙江交工金筑交通建设有限公司 | Construction method of soft foundation embankment |
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