CN114808554A - Ballastless track foundation of high-speed railway and processing method - Google Patents
Ballastless track foundation of high-speed railway and processing method Download PDFInfo
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- CN114808554A CN114808554A CN202210492434.2A CN202210492434A CN114808554A CN 114808554 A CN114808554 A CN 114808554A CN 202210492434 A CN202210492434 A CN 202210492434A CN 114808554 A CN114808554 A CN 114808554A
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- 238000003672 processing method Methods 0.000 title abstract description 5
- 238000010276 construction Methods 0.000 claims abstract description 40
- 239000002689 soil Substances 0.000 claims abstract description 34
- 238000000034 method Methods 0.000 claims abstract description 27
- 238000005056 compaction Methods 0.000 claims abstract description 17
- 239000004576 sand Substances 0.000 claims abstract description 15
- 238000012545 processing Methods 0.000 claims abstract description 5
- 239000004744 fabric Substances 0.000 claims abstract 5
- 239000010410 layer Substances 0.000 claims description 72
- 239000004746 geotextile Substances 0.000 claims description 22
- 238000012360 testing method Methods 0.000 claims description 21
- 239000004575 stone Substances 0.000 claims description 14
- 239000000203 mixture Substances 0.000 claims description 12
- 238000013461 design Methods 0.000 claims description 10
- 239000000463 material Substances 0.000 claims description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 8
- 238000005553 drilling Methods 0.000 claims description 7
- 238000004458 analytical method Methods 0.000 claims description 6
- 239000000945 filler Substances 0.000 claims description 4
- 230000009191 jumping Effects 0.000 claims description 4
- 239000002344 surface layer Substances 0.000 claims description 4
- 238000002360 preparation method Methods 0.000 claims description 3
- 230000003014 reinforcing effect Effects 0.000 claims description 3
- 238000005096 rolling process Methods 0.000 claims description 3
- 238000005070 sampling Methods 0.000 claims description 3
- 239000002352 surface water Substances 0.000 claims description 3
- 230000000694 effects Effects 0.000 abstract description 4
- 230000007613 environmental effect Effects 0.000 abstract description 3
- 230000004224 protection Effects 0.000 abstract description 3
- 238000007689 inspection Methods 0.000 description 4
- 238000005520 cutting process Methods 0.000 description 3
- 238000001514 detection method Methods 0.000 description 3
- 239000010881 fly ash Substances 0.000 description 3
- 238000003780 insertion Methods 0.000 description 3
- 230000037431 insertion Effects 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 230000035515 penetration Effects 0.000 description 3
- 239000004568 cement Substances 0.000 description 2
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01B—PERMANENT WAY; PERMANENT-WAY TOOLS; MACHINES FOR MAKING RAILWAYS OF ALL KINDS
- E01B1/00—Ballastway; Other means for supporting the sleepers or the track; Drainage of the ballastway
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01B—PERMANENT WAY; PERMANENT-WAY TOOLS; MACHINES FOR MAKING RAILWAYS OF ALL KINDS
- E01B2/00—General structure of permanent way
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/22—Piles
- E02D5/34—Concrete or concrete-like piles cast in position ; Apparatus for making same
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D7/00—Methods or apparatus for placing sheet pile bulkheads, piles, mouldpipes, or other moulds
- E02D7/20—Placing by pressure or pulling power
Abstract
The invention relates to the technical field of railway engineering, in particular to a ballastless track foundation of a high-speed railway and a processing method, comprising gravel piles, CFG piles, pile caps, a cushion layer, an embankment body, a foundation bed bottom layer and geotechnical cloth, wherein the geotechnical cloth is provided with preloading filling soil, and the liquefaction characteristic of sandy soil is solved by adopting a foundation processing mode of combining discrete gravel piles and rigid CFG piles and utilizing the replacement and compaction effects of the gravel piles; the CFG piles penetrate through the liquefied sand layer, so that the rigidity and the bearing capacity of the foundation are improved, and the deformation of the foundation is reduced; and finally, eliminating the post-construction settlement after embankment filling through the preloading for not less than 6 months. The treatment method is simple to operate, meets the requirement of environmental protection, and has wide popularization and application prospects.
Description
Technical Field
The invention relates to the technical field of railway engineering, in particular to a ballastless track foundation of a high-speed railway and a processing method.
Background
Newly-built tibet Sichuan railway faces many challenges such as engineering environment complicacy, unfavorable geology and extreme geological disasters along the line. In a section from a pond to a mapuer dam, a circuit mainly passes through a filled roadbed, a large number of thicker sandy soil layers and sandy soil liquefaction exist in the section, and the liquefaction depth is about 0-25 m.
The traditional sand pile method, gravel pile method and the like are adopted to treat the liquefaction of the foundation, although the effective sand liquefaction is realized, the later-stage settlement of the foundation is overlarge, the strict control requirement of zero settlement of the ballastless track of the high-speed railway is difficult to meet, and the later-stage safe operation of the railway has great potential safety hazard.
Disclosure of Invention
The invention aims to provide a ballastless track foundation of a high-speed railway and a treatment method, and solves the technical problem that the later settlement of the foundation is overlarge due to the treatment of the liquefaction of the foundation by a traditional sand pile method, a gravel pile method and the like.
In order to achieve the purpose, the invention provides a high-speed railway ballastless track foundation which comprises a plurality of gravel piles, CFG piles, pile caps, a cushion layer, an embankment body, a foundation bed bottom layer and geotextile, wherein the gravel piles are uniformly arranged in a fine sand layer at intervals, the CFG piles are uniformly arranged in the fine sand layer at intervals and are staggered with the gravel piles, the pile caps are arranged at the top ends of the CFG piles, the cushion layer is laid above the pile caps, the embankment body is arranged above the cushion layer, the foundation bed bottom layer is arranged above the embankment body, the geotextile is laid above the foundation bed bottom layer, and the preloading filling soil is arranged above the geotextile.
Wherein, the bed course includes rubble layer and geogrid, the quantity of rubble layer is the three-layer, the quantity of geogrid is two, the rubble layer with geogrid is crisscross to be laid in a plurality of the top of pile cap.
The height of the gravel layer is 2m, and the preloading height of the preloading filling soil is 3 m.
And the geotextile is folded back on the top surface of the preloading filling, and the width of each side is not less than 2.5 m.
The invention also provides a method for processing the ballastless track foundation of the high-speed railway, which comprises the following steps of:
step 1: construction preparation;
step 2: pile position lofting, marking pile cores of the gravel piles and the CFG piles, outer contours of the piles and edge lines of a reinforcing area;
and step 3: firstly, constructing the gravel pile, and adopting a vibration pipe sinking pile forming method, wherein when the pile machine is in place, a rack needs to be horizontally stable, a sinking pipe is vertically centered, and the sinking pipe is vibrated to a designed depth;
and 4, step 4: stopping vibration, filling materials and pressurizing to form a pile;
and 5: repeating the step 3 to the step 4 until the construction of the gravel pile is completed;
step 6: the pile forming quality of the gravel pile is tested;
and 7: constructing the CFG pile, wherein the CFG pile adopts long spiral drilling, the pile driver is in place, a drill rod is adjusted to be vertical to the ground and aligned with the center of the pile position, a drill bit valve is closed, a drill bit is moved downwards to the ground to start drilling, the speed is reduced firstly and then is increased secondly, the drill bit is drilled to the designed depth, and the drill is stopped;
and 8: pouring the mixture, starting pipe drawing after the drill pipe core pipe is filled with the mixture, and drawing the pipe to the pile top at a constant speed;
and step 9: repeating the step 7 to the step 8 until the CFG pile construction is completed;
step 10: the quality of the CFG pile is tested;
step 11: constructing the pile cap of the CFG pile;
step 12: paving the cushion layer, and filling and compacting the embankment body soil in a layered manner until the top surface of the bottom layer of the foundation bed is reached;
step 13: paving a layer of geotextile on the top surface of the bottom layer of the foundation bed, and filling and compacting the pre-compaction load filling in layers;
step 14: after the pre-compaction period is reached, by settlement observation and post-construction settlement analysis, when the analysis result meets the design requirement, the pre-compaction load filling and unloading can be carried out in a layered mode;
step 15: and after unloading, performing foundation bed surface layer filling and upper track structure construction.
Wherein, the step 1 specifically comprises:
removing surface soil, finishing temporary drainage, leveling a field, sampling and retesting surface water, underground water and construction water quality in a section, investigating, verifying, migrating and modifying pipelines in a construction influence range, carrying out an indoor proportioning test on the CFG pile, and carrying out a pile forming manufacturability test on the gravel pile and the CFG pile.
Wherein, the step 3 specifically comprises:
the construction of the gravel pile is carried out from two sides to the middle, and the pile in the middle is subjected to row-by-row pile-by-pile jumping construction; the sinking pipe is aligned with the pile position in a free state, the vibration hammer is started to vibrate and sink after the hammer weight and the self weight of the sinking pipe are utilized to slowly and statically press for 1-2 m, and the vibration is kept for 5-10 s after the sinking is carried out for 0.5-1.0 m until the design depth.
Wherein, the step 13 specifically comprises:
the height of the preloading is 3m, after a layer of geotextile is laid on the top surface of the bottom layer of the foundation bed, a layer of 0.4m is filled and compacted in a layering mode, the compaction is compacted by a medium-sized rolling machine until the filling is finished, the geotextile is folded back to the top surface of the preloading soil to ensure that the width of each side of the top surface of the preloading soil is not less than 2.5m after the filling is finished, and the geotextile is compacted and fixed by soil pressure, so that the loss of the preloading filler and the pollution to the foundation bed are avoided.
According to the ballastless track foundation of the high-speed railway and the processing method, a foundation processing mode of combining the discrete gravel pile and the rigid CFG pile is adopted, and the liquefaction characteristic of sandy soil is solved by utilizing the replacement and compaction functions of the gravel pile; the CFG piles penetrate through the liquefied sand layer, so that the rigidity and the bearing capacity of the foundation are improved, and the deformation of the foundation is reduced; and finally, eliminating the post-construction settlement after embankment filling through the preloading for not less than 6 months. The treatment method is simple to operate, meets the requirement of environmental protection, and has wide popularization and application prospects.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below.
Fig. 1 is a schematic cross-sectional view of a ballastless track foundation of a high-speed railway provided by the invention.
FIG. 2 is a pile space lofting schematic diagram of a ballastless track foundation of a high-speed railway provided by the invention.
Fig. 3 is a rough drawing of a cushion layer of a ballastless track foundation of a high-speed railway provided by the invention.
FIG. 4 is a schematic design view of a preloading vertical section of a ballastless track foundation of a high-speed railway provided by the invention.
FIG. 5 is a construction flow chart of the construction method of the ballastless track foundation of the high-speed railway provided by the invention.
1-gravel pile, 2-CFG pile, 3-pile cap, 4-cushion layer, 5-embankment body, 6-foundation bed bottom layer, 7-geotextile, 8-preloading filling, 9-foundation bed surface layer, 401-gravel layer and 402-geogrid.
Detailed Description
Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, and the embodiments described below with reference to the accompanying drawings are exemplary and intended to be illustrative of the present invention and should not be construed as limiting the present invention.
Referring to fig. 1-4, the invention provides a high-speed railway ballastless track foundation, which comprises gravel piles 1, CFG piles 2, pile caps 3, a cushion layer 4, an embankment body 5, a foundation bed bottom layer 6 and geotextile 7, wherein the gravel piles 1 are arranged in plurality, the gravel piles 1 are uniformly arranged in a fine sand layer at intervals, the CFG piles 2 are arranged in plurality, the CFG piles 2 are uniformly arranged in the fine sand layer at intervals and are staggered with the gravel piles 1, the pile caps 3 are arranged at the top ends of the CFG piles 2, the cushion layer 4 is laid above the pile caps 3, the embankment body 5 is arranged above the cushion layer 4, the foundation bed bottom layer 6 is arranged above the embankment body 5, the geotextile 7 is laid above the foundation bed bottom layer 6, and the geotextile 7 is provided with preloading soil 8, the cushion layer 4 comprises three gravel layers 401 and two geogrids 402, the gravel layers 401 are three in number, the geogrids 402 are two in number, the gravel layers 401 and the geogrids 402 are alternately laid above a plurality of pile caps 3,
in the embodiment, a foundation treatment mode combining the discrete gravel pile 1 and the rigid CFG pile 2 is adopted, and the liquefaction characteristic of sandy soil is solved by utilizing the replacement and compaction functions of the gravel pile 1; the CFG piles 2 penetrate through the liquefied sand layer, so that the rigidity and the bearing capacity of the foundation are improved, and the deformation of the foundation is reduced; and finally, eliminating the post-construction settlement after embankment filling through the preloading for not less than 6 months. The treatment method is simple to operate, meets the requirement of environmental protection, and has wide popularization and application prospects.
Referring to fig. 5, the invention further provides a method for processing a ballastless track foundation of a high-speed railway, which includes the following steps:
s1: construction preparation;
the specific method comprises the following steps: removing surface soil, draining water temporarily, leveling the field, sampling and retesting surface water, underground water and construction water quality in the section, investigating, verifying, migrating and modifying pipelines in the construction influence range, carrying out an indoor proportioning test on the CFG pile 2, and carrying out a pile forming manufacturability test on the gravel pile 1 and the CFG pile 2.
S2: pile position lofting, marking the pile cores of the gravel piles 1 and the CFG piles 2, the outer contours of the piles and the edge lines of a reinforcing area;
s3: firstly, constructing the gravel pile 1, and adopting a vibration pipe sinking pile forming method, wherein when the pile machine is in place, a rack needs to be horizontally stable, a sinking pipe is vertically centered, and the sinking pipe is vibrated to a designed depth;
the specific method comprises the following steps: the construction of the gravel pile 1 is carried out from two sides to the middle, and the pile in the middle is subjected to row-by-row pile-by-pile jumping construction; the sinking pipe is aligned with the pile position in a free state, the vibration hammer is started to vibrate and sink after the hammer weight and the self weight of the sinking pipe are utilized to slowly and statically press for 1-2 m, and the vibration is kept for 5-10 s after the sinking is carried out for 0.5-1.0 m until the design depth.
S4: stopping vibration, filling materials and pressurizing to form a pile;
the specific method comprises the following steps: after the holes are formed by vibration, stopping vibrating and filling materials to full, vibrating first and then starting tube drawing, drawing while vibrating, wherein the height of each tube drawing is 0.5-1.0 m, the reverse insertion depth is 0.3-0.5 m, and the tube drawing vibration is stopped for 5-10 s. The reverse insertion is carried out for several times until all the broken stones in the pile pipe are thrown out, and the pile length of the first feeding pile is less than half of the length of the pile pipe. And (5) feeding the crushed stone for the second time from the air by using a hopper until the crushed stone is fully filled, vibrating and pulling the pipe, and reversely inserting the pipe for a plurality of times until all the crushed stone in the pipe is fed out. And (4) lifting the pile pipe to be higher than the ground, stopping vibrating, feeding the material to the ground from the orifice, reversely inserting and supplementing the material, and repeating for several times until the design materials are used up. After the reverse insertion is finished, the material is filled to the ground, the immersed tube is dropped to the pile top, the pressurizing steel wire rope is tightened, the pile is formed by pressurization, and the elevation of the pile top is well controlled.
S5: repeating S3-S4 until the construction of the gravel pile 1 is completed;
s6: the pile forming quality of the gravel pile 1 is tested;
the specific method comprises the following steps: the contents of the quality inspection of the gravel pile 1 comprise the compactness of a pile body, a single-pile bearing capacity test and the compactness of soil between piles. The compactness of the pile body is randomly tested by adopting dynamic sounding, and the testing quantity is 2 percent of the total number of the pile holes and is not less than 3. The single pile bearing capacity test adopts a single pile flat plate load test, and the test quantity is 2 per mill of the total number of the pile holes and is not less than 3. The soil between piles adopts a standard penetration test, the actual measured standard penetration hammering number of the test is larger than the liquefaction critical standard penetration hammering number, the detection number is 2 percent of the total number of the pile holes and is not less than 3 points, and the detection position is arranged at the center of an equilateral triangle or a square.
S7: constructing the CFG pile 2, wherein the CFG pile 2 adopts long spiral drilling, a pile driver is in place, a drill rod is adjusted to be vertical to the ground and aligned with the center of a pile position, a drill bit valve is closed, a drill bit is moved downwards to the ground to start drilling, the speed is firstly slow and then fast, the drill bit is drilled to the designed depth, and the drill is stopped;
s8: pouring the mixture, starting pipe drawing after the drill pipe core pipe is filled with the mixture, and drawing the pipe to the pile top at a constant speed;
s9: repeating S7-S8 until the construction of the CFG pile 2 is completed;
s10: the quality of the CFG pile is tested;
the specific method comprises the following steps: detecting the integrity of the pile body by adopting low strain after 7 days of pile forming, wherein the detection number is 10 percent of the total pile number and is not less than 3; after forming the pile for 28 days, vertically drilling holes at the center of the pile body and in the pile length range for coring, observing the integrity and uniformity of the pile body, taking not less than 3 samples at different depths on, in and under the pile body for carrying out a compressive strength test, wherein the test quantity is 2 per mill of the total number of the constructed piles and is not less than 3; and after 28d of pile forming, strength and single-pile bearing capacity tests are carried out, and the test quantity is 2 per mill of the total pile number and is not less than 3.
S11: constructing the pile cap 3 of the CFG pile 2;
the specific method comprises the following steps: before the construction of the pile cap 3, a pile head needs to be chiseled, and a circular cutting process needs to be adopted when the pile head is chiseled. Strictly lofting according to design elevation, marking the tangent line of the ring, and adopting manual chiseling to open the gap to ensure that the ring cutting operation does not influence the integrity of the pile
S12: paving the cushion layer 4, and filling and compacting the embankment body 5 in layers until the top surface of the foundation bed bottom layer 6 is reached;
s13: laying a layer of geotextile 7 on the top surface of the foundation bed bottom layer 6, and filling and compacting the preloading filling soil 8 in layers;
the specific method comprises the following steps: the height of the preloading is 3m, after a layer of geotextile 7 is laid on the top surface of the bottom layer 6 of the foundation bed, a layer of 0.4m is used for filling and layering compaction, the compaction is compacted by adopting a medium-sized rolling machine, after the filling is finished, the geotextile 7 is folded back to the width of each side of the top surface of the preloading soil to be not less than 2.5m and is fixed by soil compaction, and the loss of the preloading filler and the pollution to the roadbed are avoided.
S14: after the pre-compaction period is reached, by settlement observation and post-construction settlement analysis, when the analysis result meets the design requirement, the pre-compaction load filling and unloading can be carried out in a layered mode;
s15: and after unloading, filling the surface layer 9 of the foundation bed and constructing the upper track structure.
In step S1, the diameter of the gravel pile 1 is 0.5m, and the gravel pile 1 should be subjected to pile-forming manufacturability tests on representative sections, so as to determine technological parameters of the gravel pile 1, such as pipe-drawing height, vibration density current, vibration retention time, segmental gravel filling amount, filling rate and the like, and check pile-forming effect; the diameter of the CFG pile 2 is 0.5m, an indoor proportioning test is carried out according to design parameters before the CFG pile 2 is constructed, and the mixture proportioning is selected. And selecting a representative section to perform a pile forming manufacturability test, and determining construction processes and parameters of the CFG pile 2, such as mixture construction mix proportion, slump, mixture pumping quantity, pipe drawing speed, final hole current and the like.
In step S3, the gravel pile 1 construction should be performed from two sides to the middle, and the middle pile is subjected to row-by-row pile-spacing jumping construction; the error between the center of the pile tube bottom plate and the pile position is required to be less than or equal to 2cm, the deviation of the verticality of the immersed tube is required to be less than or equal to 1.5H%, and the verticality of the pile tube is tracked and checked at any time in the piling process.
In step S4, the pile body is made of hard materials with stable performance, such as hard and difficult-to-weather clean gravel, pebble, gravel sand containing stone, slag and the like, the mud content is not more than 5%, and the particle size is preferably 20-50 mm.
In step S6, after the gravel pile 1 is constructed, quality inspection can be performed on the sandy soil section at an interval of more than 7 days. The contents of the quality inspection of the gravel pile 1 comprise the compactness of a pile body, a single-pile bearing capacity test and the compactness of soil between piles.
In step S7, the CFG pile 2 construction is preferably performed from the middle to the periphery, so as to avoid damage to the constructed pile due to the subsequent pile construction.
In step S8, the pile body material is formed by mixing broken stone, stone chips or sand, fly ash and cement with water, the pile body cement is P.O 42.5.5-grade ordinary portland cement, the pile body mixture is proportioned according to C15 concrete, the 28-day standard cubic unconfined compressive strength of the mixture is not less than 15MPa, high-quality fly ash (grade is not less than grade III) is added, and the mixing amount of the fly ash is 70-90 kg/m 3 . The maximum particle size of the crushed stone is not more than 25 mm.
In step S10, the quality inspection content of the shaft of the CFG pile 2 should include the integrity, uniformity, strength, bearing capacity of single pile or composite foundation, etc.
In step S11, the pile cap 3 has a size of 1.1m × 1.1m and a thickness of 0.35 m. Before the construction of the pile cap 3, a pile head needs to be chiseled, and a circular cutting process needs to be adopted when the pile head is chiseled.
In step S12, the two-layer geogrid 402 with 0.6m broken stone sandwiched between the two layers is adopted as the cushion layer 4, the broken stones in the cushion layer 4 are clean sand gravel or broken stones with good gradation, the maximum particle size of the broken stones is not more than 30mm, the mud content is not more than 5%, and the broken stones do not contain impurities such as grass roots, garbage and the like; the geogrid 402 model in the cushion layer 4 is GGR/PET/BW80-80, the ultimate tensile strength is more than or equal to 80kN/m, the mass per unit area is more than or equal to 600 g/square meter, the size of an inner hole is 30-60 mm, the width is 3-5 m, the tensile strength at 2% elongation in the longitudinal direction and the transverse direction is more than or equal to 36kN/m, the tensile strength at 5% elongation in the longitudinal direction and the transverse direction is more than or equal to 64kN/m, the nominal elongation in the longitudinal direction and the transverse direction is less than or equal to 8%, the ultimate peel force of a welding point is more than or equal to 100kN, and the retention rate of ultraviolet resistance is more than or equal to 80%. Through laying the bed course 4, be favorable to the effect of horizontal drainage for the soil layer accelerates to consolidate after the construction, secondly can play obvious stress diffusion effect, thereby improves composite foundation bearing capacity, reduces the foundation and warp.
In step S13, the slope ratio of the pre-compacted soil filled cross section side slope is 1: 1, the slope rate of the longitudinal side slope is 1: 5. after filling, the geotextile 7 is folded back to the top surface of the prepressing soil, the width of each side is not less than 2.5m, and the geotextile is compacted and fixed by soil, so that the loss of the prepressing filler and the pollution to a roadbed are avoided; the thickness of each layer of the pre-compaction soil filling is not more than 0.4m, the preloading height is 3m, and the pre-compaction period is not less than 6 months generally.
While the above disclosure describes one or more preferred embodiments of the present invention, it is not intended to limit the scope of the claims to such embodiments, and one skilled in the art will understand that all or a portion of the processes performed in the above embodiments may be practiced without departing from the spirit and scope of the claims.
Claims (8)
1. A ballastless track foundation of a high-speed railway is characterized in that,
including gravel pile, CFG stake, pile cap, bed course, embankment body, foundation bed bottom and geotechnological cloth, the quantity of gravel pile is a plurality of, and is a plurality of gravel pile interval evenly sets up in the fine sand layer, the quantity of CFG stake is a plurality of, and is a plurality of CFG stake interval evenly sets up in the fine sand layer, and with a plurality of gravel pile is crisscross to be set up, every the top of CFG stake all is provided with the pile cap, the bed course is laid in a plurality of the top of pile cap, the embankment body sets up in the top of bed course, the foundation bed bottom set up in the top of embankment body, geotechnological cloth is laid in the top of foundation bed bottom, geotechnological cloth's top is provided with the preloading filling of surcharge.
2. The ballastless track foundation of claim 1, wherein,
the bed course includes rubble layer and geogrid, the quantity of rubble layer is the three-layer, the quantity of geogrid is two, the rubble layer with geogrid is crisscross to be laid in a plurality of the top of pile cap.
3. The ballastless track foundation of claim 2, wherein,
the height of the crushed stone layer is 2m, and the preloading height of the preloading filling soil is 3 m.
4. The ballastless track foundation of claim 3, wherein,
the geotextile is folded back on the top surface of the preloading filling, and the width of each side is not less than 2.5 m.
5. The method for treating the ballastless track foundation of the high-speed railway according to claim 4 is characterized by comprising the following steps of:
step 1: construction preparation;
step 2: pile position lofting, marking pile cores of the gravel piles and the CFG piles, outer contours of the piles and edge lines of a reinforcing area;
and step 3: firstly, constructing the gravel pile, and adopting a vibration pipe sinking pile forming method, wherein when the pile machine is in place, a rack needs to be horizontally stable, a sinking pipe is vertically centered, and the sinking pipe is vibrated to a designed depth;
and 4, step 4: stopping vibration, filling materials and pressurizing to form a pile;
and 5: repeating the step 3 to the step 4 until the construction of the gravel pile is completed;
step 6: the pile forming quality of the gravel pile is tested;
and 7: constructing the CFG pile, wherein the CFG pile adopts long spiral drilling, the pile driver is in place, a drill rod is adjusted to be vertical to the ground and aligned with the center of the pile position, a drill bit valve is closed, a drill bit is moved downwards to the ground to start drilling, the speed is reduced firstly and then is increased secondly, the drill bit is drilled to the designed depth, and the drill is stopped;
and 8: pouring the mixture, starting pipe drawing after the drill pipe core pipe is filled with the mixture, and drawing the pipe to the pile top at a constant speed;
and step 9: repeating the step 7 to the step 8 until the CFG pile construction is completed;
step 10: the quality of the CFG pile is tested;
step 11: constructing the pile cap of the CFG pile;
step 12: paving the cushion layer, and filling and compacting the embankment body filled soil in layers until the top surface of the bottom layer of the foundation bed is reached;
step 13: paving a layer of geotextile on the top surface of the bottom layer of the foundation bed, and filling and compacting the preloading filling soil in layers;
step 14: after the pre-compaction period is reached, by settlement observation and post-construction settlement analysis, when the analysis result meets the design requirement, the pre-compaction load filling and unloading can be carried out in a layered mode;
step 15: and after unloading, performing foundation bed surface layer filling and upper track structure construction.
6. The method for treating the foundation of the ballastless track of the high-speed railway according to claim 5, wherein the step 1 specifically comprises:
removing surface soil, finishing temporary drainage, leveling a field, sampling and retesting surface water, underground water and construction water quality in a section, investigating, verifying, migrating and modifying pipelines in a construction influence range, carrying out an indoor proportioning test on the CFG pile, and carrying out a pile forming manufacturability test on the gravel pile and the CFG pile.
7. The method for treating the foundation of the ballastless track of the high-speed railway according to claim 6, wherein the step 3 specifically comprises:
the construction of the gravel pile is carried out from two sides to the middle, and the pile in the middle is subjected to row-by-row pile-by-pile jumping construction; the sinking pipe is aligned with the pile position in a free state, the vibration hammer is started to vibrate and sink after the hammer weight and the self weight of the sinking pipe are utilized to slowly and statically press for 1-2 m, and the vibration is kept for 5-10 s after the sinking is carried out for 0.5-1.0 m until the design depth.
8. The method for processing the foundation of the ballastless track of the high-speed railway according to claim 7, wherein the step 13 specifically comprises:
the height of the preloading is 3m, after a layer of geotextile is laid on the top surface of the bottom layer of the foundation bed, a layer of 0.4m is filled and compacted in a layering mode, the compaction is compacted by a medium-sized rolling machine until the filling is finished, the geotextile is folded back to the top surface of the preloading soil to ensure that the width of each side of the top surface of the preloading soil is not less than 2.5m after the filling is finished, and the geotextile is compacted and fixed by soil pressure, so that the loss of the preloading filler and the pollution to the foundation bed are avoided.
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