CN109914161B - Construction method of high-speed railway filling roadbed in soft soil area - Google Patents
Construction method of high-speed railway filling roadbed in soft soil area Download PDFInfo
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- CN109914161B CN109914161B CN201910287409.9A CN201910287409A CN109914161B CN 109914161 B CN109914161 B CN 109914161B CN 201910287409 A CN201910287409 A CN 201910287409A CN 109914161 B CN109914161 B CN 109914161B
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Abstract
The invention discloses a construction method of a high-speed railway fill roadbed in a soft soil area, which comprises the following steps: (1) clearing and leveling the original ground; (2) constructing rigid piles in the range of the load influence line; the site finishes surface cleaning and leveling, and rigid piles in the range of load influence lines are constructed after foundation detection is qualified; (3) reinforcing soil between a slope toe and a load influence range line by the composite foundation; (4) constructing a bearing plate on the pile plate structure; (5) paving a broken stone cushion layer and a high-strength geogrid; laying a mattress layer after the construction of the pile plate structure bearing plate and the composite foundation treatment measures on the two sides is finished; (6) and constructing the light foam concrete within the filling range after the composite foundation is detected to be qualified. The invention can achieve the beneficial effects of ensuring the construction quality of the filling roadbed in the soft soil area of the high-speed railway, ensuring the reliability of roadbed filling filler construction, ensuring the stability of the roadbed and the qualification of roadbed settlement after construction, and ensuring that the roadbed does not generate diseases.
Description
Technical Field
The invention belongs to the technical field of high-speed railway roadbed construction, and particularly relates to a construction method of a high-speed railway fill roadbed in a soft soil area.
Background
The construction of high-speed railways is the need for rapid economic development and great improvement of railway transportation capacity, and is one of the important signs whether the country is developed or not, developed countries in the world such as Japan, France and Germany have built relatively high-efficiency and beautiful high-speed rail nets in the nineteenth century, and the pulling effect on economic development and urbanization construction along high-speed rails is particularly obvious. The high-speed railway technology is researched from the nineteenth century, large-scale construction and continuous opening are started in 2004, and the operating mileage of the high-speed railway built into a communication car in China is nearly 3 kilometres. In the design of high-speed railways, professional detailed design determines the stability and safety of railway operation, and particularly, the requirement of millimeter-scale settlement control in high-speed railway base design is a central importance in high-speed railway design.
For a common-speed ballast track railway, the settlement requirement of the roadbed is in the centimeter-level range, so that the proportion of roadbed engineering is higher, and the proportion of the roadbed of a railway with a slightly lower grade is 80%. However, for a ballastless track high-speed railway with the speed of 250km/h and above, the adjustability of the track is in the millimeter level, and the settlement control standard relative to the roadbed needs to meet the requirement of the millimeter level, so that the bridge and tunnel ratio of the currently constructed high-speed railway is nearly 90%. However, because the roadbed engineering has obvious advantages over the economy of bridge and tunnel engineering, on the premise of meeting the requirements of post-construction settlement control and high-speed rail function, the proportion of the high-speed rail roadbed is properly improved, and the method plays an important role in reducing the investment of the whole high-speed railway.
The railway is a ballastless track main line high-speed railway of 350km/h in China, the technical standard is high, the section of engineering passes through roadbed filling, the filling height is about 4m, the surface of a stratum in the engineering range is covered by powder clay of a residual layer of a fourth system of all-new-system slope, the clay contains gravel powder clay and fine-angle gravel soil, the covering layer is thicker and larger than 30m, the lower system of the three-stack system is the Feixian group siltstone, the underground water type is fourth system pore diving and bed rock fracture water, the burial depth is 3.5 m-7.8 m, and the special rock soil is soft soil and soft soil.
Because the roadbed filling material at the section is the group C, the requirement of qualified filling material in the roadbed bed range can not be met, and the conventional method can meet the requirement of filling material by adding and mixing cement for improvement. Meanwhile, settlement calculation is carried out according to the condition of additional load loading on the foundation within a certain range, and reinforcement treatment needs to be carried out within a certain range so as to meet the settlement requirement of the subgrade after construction. If the roadbed construction point is designed by adopting a conventional method, the filling improvement process is complex and has great influence on the surrounding environment, and simultaneously the filling load is increased, and the additional stress is increased, so that the foundation treatment depth is deepened, namely the foundation treatment cost is increased.
Disclosure of Invention
Aiming at the technical problems in the prior art, the invention provides the construction method of the filling roadbed of the high-speed railway in the soft soil area, which can achieve the beneficial effects of ensuring the construction quality of the filling roadbed of the high-speed railway soft soil area, ensuring the reliability of the filling filler construction of the roadbed, ensuring the stability of the roadbed and the qualification of the settlement of the roadbed after construction, and ensuring that the roadbed does not generate diseases.
In order to solve the technical problems, the invention adopts the technical scheme that: a construction method of a filling roadbed of a high-speed railway in a soft soil area comprises the following steps:
(1) clearing and leveling the original ground;
(2) constructing rigid piles in the range of the load influence line;
the site finishes surface cleaning and leveling, and rigid piles in the range of load influence lines are constructed after foundation detection is qualified;
(3) reinforcing soil between a slope toe and a load influence range line by the composite foundation;
(4) constructing a bearing plate on the pile plate structure;
after the bored pile is qualified, arranging a bearing plate on the bored pile to transfer the filling soil and the train load to the deep part of the foundation, wherein the bearing plate is effectively anchored and connected with the reserved steel bars on the bored pile;
(5) paving a broken stone cushion layer and a high-strength geogrid;
after the construction of the pile plate structure bearing plate and the composite foundation treatment measures on the two sides is finished, a mattress layer is laid according to the requirements of building foundation treatment technical specifications and railway engineering foundation treatment technical specifications;
(6) and constructing the light foam concrete within the filling range after the composite foundation is detected to be qualified.
Preferably, in the step (1), before roadbed construction, the site is subjected to surface cleaning and leveling treatment, so that the site base is free of turf, tree roots and other impurities and accumulated water, the original ground base is compact and flat, pit treatment is thorough, and potential quality hazards are avoided; the construction of the project of clearing and leveling the surface of the area adopts the combined operation of an excavator, a loader, a bulldozer and a road roller, and the manual cooperation and the transportation construction of a dump truck.
Preferably, the specific construction process flow of the step (1) is as follows:
preparing the position and elevation of a red line by a measurer according to a construction drawing, and clearly marking the position and elevation with lime; the organic soil, planting soil, garbage and the like in the red line range are cleaned by matching an excavator, a loading and unloading machine, a bulldozer and a dump truck; field management and technicians determine the position of the red line pile; for the areas of the site parcel where the dispute is not solved, indicating and marking the areas, and irreparably and irreconcilably re-constructing; the personnel and the machinery of the construction operation team can not damage the red line and the side pile;
before construction, safety workers and managers carry out safety education and training on the construction workers to prevent accidents; the mechanical parking must ensure stable parking;
after the roots are dug out in the waterless area in the field, temporary drainage and water retaining projects must be built firstly before the surface is cleared; in the water-containing area, the accumulated water on the earth surface must be dredged and drained and the waterproof and drainage work in rainy season must be done; constructing a 1-meter high-retaining soil cofferdam in a watery area, and digging tree roots and the like after the construction is finished;
cutting or transplanting trees, shrubs, weeds and the like in a field range for cleaning, stacking the cleaned surface soil and humus soil containing plant roots in a centralized manner, and uniformly transporting the soil to a spoil area as soil for secondary tillage of the spoil area;
filling and compacting the artificially-formed pits after the removal is finished, and rolling the pits until the specified compactness is achieved; when the surface is cleaned, a temporary drainage measure is made, the original surface accumulated water is drained, and the underground water leakage in the basic range is strictly treated according to the design requirement;
and (4) sampling and performing foundation test detection after surface cleaning and leveling, and performing construction of the next procedure after the requirement is met.
Preferably, in the step (2), the rigid pile is in the form of a pre-stressed pipe pile prefabricated in a factory or a cast-in-situ bored pile;
drilling the cast-in-situ pile by adopting a rotary drilling rig, and forming the pile by pouring concrete underwater after mud protecting walls;
the specific construction process flow is as follows:
pile position lofting and rechecking: performing pile position lofting and rechecking by using a total station or RTK according to the datum point to ensure that the pile position deviation meets the standard requirement;
pile foundation in-place and centering: after confirming the pile position of the pile to be constructed without errors, positioning a drilling machine according to the preset pile position, stopping the drilling machine on the hard ground, adjusting mast deviation, ensuring that pile displacement and inclination do not exceed standards, and performing irregular inspection and adjustment in the process of forming holes;
preparing slurry: the self pore-forming process of the rotary drilling rig determines that the slurry making capability is poor, so all the used slurry is high-quality high-plasticity clay premixed in advance, the specific gravity of the stirred slurry is 1.1-1.15, and the slurry is added and purified in time along with the construction progress; the quality of hole forming and pile forming is ensured;
drilling: during drilling, the drilling speed is mastered according to the soil layer condition, and the lifting speed of the drilling bucket in the hole is strictly controlled; when the hole is drilled to the depth required by the design, the hole depth is measured on site by constructors and supervision engineers together, and the hole depth is used as the basis of the final hole depth;
slag removal of a drilling machine: after the drilling hole reaches the designed depth, slightly lifting the drilling tool, and cleaning sediments at the bottom of the hole by using the drilling tool;
manufacturing and placing a reinforcement cage: the reinforcement cage is manufactured on site, the stirrups and the main reinforcements are firmly bound at each node, and the reinforcement cage is slowly placed to prevent collision with the hole wall;
placing a catheter: the conduit is connected by a phi 250 screw fastener, each section is 2.5m in length, and the bottom tube is 4.5m in length; assembling and pressure testing are carried out before use, and the water pressure during the test is at least 1.5 times greater than the water depth in the well; the guide pipe is placed by adopting a truck crane, and the bottom of the guide pipe is placed to be 50cm away from the bottom of the hole;
pouring concrete: pre-mixed commercial concrete is adopted, and a pump is adopted to directly connect the pre-mixed commercial concrete into a collecting hopper; the concrete is firstly poured by adopting enough concrete reserve quantity, so that the guide pipe is embedded into the concrete surface for more than 1m at one time; the concrete has good workability, the slump is controlled to be 16-22 cm, and the slump of the concrete for each pile is subjected to sampling inspection for not less than 1 time;
and after the construction of the cast-in-situ bored pile is finished, the construction is carried out according to the requirements of technical regulations for detecting foundation piles in railway engineering, and the construction of the next procedure is carried out after the detection is qualified.
Preferably, in the step (3), according to different geological conditions, semi-rigid composite foundation treatment measures such as cement mixing piles or multi-directional mixing cement mortar piles and the like are adopted to reinforce soil bodies between the slope toe of the embankment and the load influence line, and before reinforcement, construction can be carried out by ensuring that the strength of the rigid piles in the load influence line range reaches the design requirement so as to avoid influencing the strength and the verticality of the rigid piles; the construction sequence of the composite foundation is carried out from the rigid pile to the slope toe of the embankment;
the stirring pile adopts two-spraying four-stirring steps, and the construction process flow comprises the following steps: the pile driver is in place and leveled; stirring and drilling to a designed depth; spraying slurry, stirring and lifting; lifting to a pulp stopping surface; re-stirring and sinking to the designed depth; lifting and stirring the gunite to a gunite stopping surface; closing the stirring machine, and moving the pile machine;
and after the construction of the composite foundation is finished, detecting the integrity, uniformity, unconfined compressive strength, single-pile bearing capacity and composite foundation bearing capacity of the pile body, wherein the detection frequency is executed according to the requirements of building foundation treatment technical specifications and railway engineering foundation treatment technical regulations.
Preferably, in the step (5), the semi-rigid composite foundation adopts a cushion layer thickness of 40cm, and the rigid pile adopts a cushion layer thickness of 60 cm;
one layer of high-strength geogrid is sandwiched between the semi-rigid pile broken stone cushion layers, two layers of high-strength geogrids are sandwiched between the rigid pile broken stone cushion layers, the maximum particle size of the broken stone cushion layers is not more than 30mm, the mud content is not more than 5%, impurities such as grass roots and garbage are not contained, the broken stone cushion layers are rolled and compacted, the compaction degree is not less than 96%, and the porosity is not more than 23%; the geogrid is a polypropylene bidirectional geogrid, the breadth is not less than 5.0m, the diameter of meshes is 80-120 mm, the longitudinal and transverse yield tensile strength is not less than 100kN/m, and the longitudinal and transverse elongation is not more than 10%; when the geogrid is laid, the geogrid is straightened and leveled, the webs are aligned with one another, and the overlapping length is not less than 15 cm; and after the compaction detection is qualified, filling soil or light foam concrete on the concrete.
Preferably, in the step (5), the cushion layer quality inspection comprises layered construction quality inspection and engineering quality acceptance; the quality and quality standard of the layered construction enable the cushion layer to reach the compactness required by the design, and the compaction coefficient lambda c reaches 0.94-0.97;
adopting a penetrometer and heavy dynamic sounding inspection to the cushion layer, and inspecting the construction quality of the cushion layer by using the penetration degree corresponding to the designed compaction coefficient as a standard through field tests;
the compaction coefficient can be detected by adopting a sand filling method, a water filling method or other methods; when a penetrometer or dynamic sounding is adopted to test the construction quality of the cushion layer, the distance between test points of each layer is less than 4 m; when the bearing capacity of the cushion layer is tested by adopting a load test in completion acceptance, each single project is not less than 3 points; the number of inspection points is determined according to the unit engineering quantity or the engineering area.
Preferably, in the step (6), the light foam concrete is one of a plurality of members in light concrete, is widely used in engineering fields such as road and bridge abutment back filling, bridgehead roadbed filling, existing line filling and the like, and can also be used for structure earthing and load reduction; in order to reduce the roadbed filling load and reduce the foundation treatment cost, the filling is formed by pouring light foam concrete; the construction process flow is as follows: metering the ingredients; preparing foam by adopting a foaming agent; adding water and an auxiliary agent into the cement and uniformly stirring; stirring by adopting foam concrete stirring equipment; pouring in situ according to the design gradient requirement; surface smoothing; arranging an expansion joint; and (5) overall maintenance.
Compared with the prior art, the invention has the beneficial effects that: the invention solves a series of technical problems that when a high-speed railway builds a filling roadbed in a soft soil area, the roadbed base is subjected to surface cleaning, leveling and long-short pile foundation treatment measures inside and outside a load influence line, and a light foam concrete material is adopted for roadbed filling for load reduction. Meanwhile, the method can also be used for the construction of highway and general-speed railway roadbed filling sections with higher requirements on post-construction settlement.
The requirement of ballastless track post-construction settlement is met; the requirement of the bearing capacity of the foundation is met; the filling load is reduced, the additional stress is reduced, and the construction cost is reduced; the construction quality of the filling roadbed in the soft soil area of the high-speed railway is ensured, the reliability of roadbed filling filler construction is ensured, the stability of the roadbed and the qualification of roadbed post-construction settlement are ensured, and the roadbed is ensured not to generate diseases.
Drawings
FIG. 1 is a schematic view of the construction method of the present invention.
In the figure, 1-rigid piles within the range of a load influence line, 2-load influence lines to slope toe semi-rigid piles, 3-broken stone cushion layer-sandwiched geogrids, 4-pile plate structure bearing plates, 5-light foam concrete, 6-load influence line schematic lines and 7-natural ground lines.
Detailed Description
In order to make the technical solutions of the present invention better understood, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
The embodiment of the invention discloses a construction method of a filling roadbed of a high-speed railway in a soft soil area, which comprises the following steps:
(1) clearing and leveling the original ground;
(2) constructing rigid piles in the range of the load influence line;
the site finishes surface cleaning and leveling, and rigid piles in the range of load influence lines are constructed after foundation detection is qualified;
(3) reinforcing soil between a slope toe and a load influence range line by the composite foundation;
(4) constructing a bearing plate on the pile plate structure;
after the bored pile is qualified, arranging a bearing plate on the bored pile to transfer the filling soil and the train load to the deep part of the foundation, wherein the bearing plate is effectively anchored and connected with the reserved steel bars on the bored pile;
(5) paving a broken stone cushion layer and a high-strength geogrid;
after the construction of the pile plate structure bearing plate and the composite foundation treatment measures on the two sides is finished, a mattress layer is laid according to the requirements of building foundation treatment technical specifications and railway engineering foundation treatment technical specifications;
(6) and constructing the light foam concrete within the filling range after the composite foundation is detected to be qualified.
Preferably, in the step (1), before roadbed construction, the site is subjected to surface cleaning and leveling treatment, so that the site base is free of turf, tree roots and other impurities and accumulated water, the original ground base is compact and flat, pit treatment is thorough, and potential quality hazards are avoided; the construction of the project of clearing and leveling the surface of the area adopts the combined operation of an excavator, a loader, a bulldozer and a road roller, and the manual cooperation and the transportation construction of a dump truck.
Preferably, the specific construction process flow of the step (1) is as follows:
preparing the position and elevation of a red line by a measurer according to a construction drawing, and clearly marking the position and elevation with lime; the organic soil, planting soil, garbage and the like in the red line range are cleaned by matching an excavator, a loading and unloading machine, a bulldozer and a dump truck; field management and technicians determine the position of the red line pile; for the areas of the site parcel where the dispute is not solved, indicating and marking the areas, and irreparably and irreconcilably re-constructing; the personnel and the machinery of the construction operation team can not damage the red line and the side pile;
before construction, safety workers and managers carry out safety education and training on the construction workers to prevent accidents; the mechanical parking must ensure stable parking;
after the roots are dug out in the waterless area in the field, temporary drainage and water retaining projects must be built firstly before the surface is cleared; in the water-containing area, the accumulated water on the earth surface must be dredged and drained and the waterproof and drainage work in rainy season must be done; constructing a 1-meter high-retaining soil cofferdam in a watery area, and digging tree roots and the like after the construction is finished;
cutting or transplanting trees, shrubs, weeds and the like in a field range for cleaning, stacking the cleaned surface soil and humus soil containing plant roots in a centralized manner, and uniformly transporting the soil to a spoil area as soil for secondary tillage of the spoil area;
filling and compacting the artificially-formed pits after the removal is finished, and rolling the pits until the specified compactness is achieved; when the surface is cleaned, a temporary drainage measure is made, the original surface accumulated water is drained, and the underground water leakage in the basic range is strictly treated according to the design requirement;
and (4) sampling and performing foundation test detection after surface cleaning and leveling, and performing construction of the next procedure after the requirement is met.
Preferably, in the step (2), the rigid pile is in the form of a pre-stressed pipe pile prefabricated in a factory or a cast-in-situ bored pile;
drilling the cast-in-situ pile by adopting a rotary drilling rig, and forming the pile by pouring concrete underwater after mud protecting walls;
the specific construction process flow is as follows:
pile position lofting and rechecking: performing pile position lofting and rechecking by using a total station or RTK according to the datum point to ensure that the pile position deviation meets the standard requirement;
pile foundation in-place and centering: after confirming the pile position of the pile to be constructed without errors, positioning a drilling machine according to the preset pile position, stopping the drilling machine on the hard ground, adjusting mast deviation, ensuring that pile displacement and inclination do not exceed standards, and performing irregular inspection and adjustment in the process of forming holes;
preparing slurry: the self pore-forming process of the rotary drilling rig determines that the slurry making capability is poor, so all the used slurry is high-quality high-plasticity clay premixed in advance, the specific gravity of the stirred slurry is 1.1-1.15, and the slurry is added and purified in time along with the construction progress; the quality of hole forming and pile forming is ensured;
drilling: during drilling, the drilling speed is mastered according to the soil layer condition, and the lifting speed of the drilling bucket in the hole is strictly controlled; when the hole is drilled to the depth required by the design, the hole depth is measured on site by constructors and supervision engineers together, and the hole depth is used as the basis of the final hole depth;
slag removal of a drilling machine: after the drilling hole reaches the designed depth, slightly lifting the drilling tool, and cleaning sediments at the bottom of the hole by using the drilling tool;
manufacturing and placing a reinforcement cage: the reinforcement cage is manufactured on site, the stirrups and the main reinforcements are firmly bound at each node, and the reinforcement cage is slowly placed to prevent collision with the hole wall;
placing a catheter: the conduit is connected by a phi 250 screw fastener, each section is 2.5m in length, and the bottom tube is 4.5m in length; assembling and pressure testing are carried out before use, and the water pressure during the test is at least 1.5 times greater than the water depth in the well; the guide pipe is placed by adopting a truck crane, and the bottom of the guide pipe is placed to be 50cm away from the bottom of the hole;
pouring concrete: pre-mixed commercial concrete is adopted, and a pump is adopted to directly connect the pre-mixed commercial concrete into a collecting hopper; the concrete is firstly poured by adopting enough concrete reserve quantity, so that the guide pipe is embedded into the concrete surface for more than 1m at one time; the concrete has good workability, the slump is controlled to be 16-22 cm, and the slump of the concrete for each pile is subjected to sampling inspection for not less than 1 time;
and after the construction of the cast-in-situ bored pile is finished, the construction is carried out according to the requirements of technical regulations for detecting foundation piles in railway engineering, and the construction of the next procedure is carried out after the detection is qualified.
Preferably, in the step (3), according to different geological conditions, semi-rigid composite foundation treatment measures such as cement mixing piles or multi-directional mixing cement mortar piles and the like are adopted to reinforce soil bodies between the slope toe of the embankment and the load influence line, and before reinforcement, construction can be carried out by ensuring that the strength of the rigid piles in the load influence line range reaches the design requirement so as to avoid influencing the strength and the verticality of the rigid piles; the construction sequence of the composite foundation is carried out from the rigid pile to the slope toe of the embankment;
the stirring pile adopts two-spraying four-stirring steps, and the construction process flow comprises the following steps: the pile driver is in place and leveled; stirring and drilling to a designed depth; spraying slurry, stirring and lifting; lifting to a pulp stopping surface; re-stirring and sinking to the designed depth; lifting and stirring the gunite to a gunite stopping surface; closing the stirring machine, and moving the pile machine;
and after the construction of the composite foundation is finished, detecting the integrity, uniformity, unconfined compressive strength, single-pile bearing capacity and composite foundation bearing capacity of the pile body, wherein the detection frequency is executed according to the requirements of building foundation treatment technical specifications and railway engineering foundation treatment technical regulations.
Preferably, in the step (5), the semi-rigid composite foundation adopts a cushion layer thickness of 40cm, and the rigid pile adopts a cushion layer thickness of 60 cm;
one layer of high-strength geogrid is sandwiched between the semi-rigid pile broken stone cushion layers, two layers of high-strength geogrids are sandwiched between the rigid pile broken stone cushion layers, the maximum particle size of the broken stone cushion layers is not more than 30mm, the mud content is not more than 5%, impurities such as grass roots and garbage are not contained, the broken stone cushion layers are rolled and compacted, the compaction degree is not less than 96%, and the porosity is not more than 23%; the geogrid is a polypropylene bidirectional geogrid, the breadth is not less than 5.0m, the diameter of meshes is 80-120 mm, the longitudinal and transverse yield tensile strength is not less than 100kN/m, and the longitudinal and transverse elongation is not more than 10%; when the geogrid is laid, the geogrid is straightened and leveled, the webs are aligned with one another, and the overlapping length is not less than 15 cm; and after the compaction detection is qualified, filling soil or light foam concrete on the concrete.
Preferably, in the step (5), the cushion layer quality inspection comprises layered construction quality inspection and engineering quality acceptance; the quality and quality standard of the layered construction enable the cushion layer to reach the compactness required by the design, and the compaction coefficient lambda c reaches 0.94-0.97;
adopting a penetrometer and heavy dynamic sounding inspection to the cushion layer, and inspecting the construction quality of the cushion layer by using the penetration degree corresponding to the designed compaction coefficient as a standard through field tests;
the compaction coefficient can be detected by adopting a sand filling method, a water filling method or other methods; when a penetrometer or dynamic sounding is adopted to test the construction quality of the cushion layer, the distance between test points of each layer is less than 4 m; when the bearing capacity of the cushion layer is tested by adopting a load test in completion acceptance, each single project is not less than 3 points; the number of inspection points is determined according to the unit engineering quantity or the engineering area.
Preferably, in the step (6), the light foam concrete is one of a plurality of members in light concrete, is widely used in engineering fields such as road and bridge abutment back filling, bridgehead roadbed filling, existing line filling and the like, and can also be used for structure earthing and load reduction; in order to reduce the roadbed filling load and reduce the foundation treatment cost, the filling is formed by pouring light foam concrete; the construction process flow is as follows: metering the ingredients; preparing foam by adopting a foaming agent; adding water and an auxiliary agent into the cement and uniformly stirring; stirring by adopting foam concrete stirring equipment; pouring in situ according to the design gradient requirement; surface smoothing; arranging an expansion joint; and (5) overall maintenance.
Before the light foam concrete of the roadbed is poured, the original surface is subjected to surface cleaning and leveling treatment, and the foundation within the load influence line is treated by adopting a rigid cast-in-place pile plate structure according to the influence line of train load so as to meet the requirement of settlement of the ballastless track after construction. And (3) processing the load influence line to the range of the embankment toe by adopting the semi-rigid stirring pile composite foundation so as to meet the requirement of the bearing capacity of the foundation. After a mattress layer with the thickness of 40-60 cm is laid on the composite foundation, light foam concrete is poured on the mattress layer, and the effects of reducing the filling load, reducing the additional stress and reducing the construction cost can be achieved. The construction method can ensure the construction quality of the filling subgrade in the soft soil area of the high-speed railway, ensure the reliability of the filling filler construction of the subgrade, ensure the stability of the subgrade and the qualification of the settlement of the subgrade after construction, and ensure that the subgrade does not generate diseases.
The present invention has been described in detail with reference to the embodiments, but the description is only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The scope of the invention is defined by the claims. The technical solutions of the present invention or those skilled in the art, based on the teaching of the technical solutions of the present invention, should be considered to be within the scope of the present invention, and all equivalent changes and modifications made within the scope of the present invention or equivalent technical solutions designed to achieve the above technical effects are also within the scope of the present invention. It should be noted that for the sake of clarity, parts of the description of the invention have been omitted where there is no direct explicit connection with the scope of protection of the invention, but where components and processes are known to those skilled in the art.
Claims (8)
1. A construction method for a filling roadbed of a high-speed railway in a soft soil area is characterized by comprising the following steps:
(1) clearing and leveling the original ground;
(2) constructing rigid piles in the range of the load influence line;
the site finishes surface cleaning and leveling, and rigid piles in the range of load influence lines are constructed after foundation detection is qualified;
(3) reinforcing the soil body between the slope toe of the embankment and the load influence line by adopting a composite foundation;
(4) constructing a bearing plate on the pile plate structure;
after the rigid pile is detected to be qualified, a bearing plate is arranged on the rigid pile to transfer filling and train load to the deep part of the foundation, and the bearing plate is effectively anchored and connected with the reserved steel bars on the rigid pile;
(5) paving a broken stone cushion layer and a high-strength geogrid;
laying a mattress layer after the construction of the pile plate structure bearing plate and the composite foundation treatment measures on the two sides is finished;
(6) and constructing the light foam concrete within the filling range after the composite foundation is detected to be qualified.
2. The construction method of the roadbed in the high-speed railway filling area in the soft soil area according to the claim 1, characterized in that in the step (1), before the roadbed construction, the roadbed is subjected to surface cleaning and leveling treatment, so that the foundation of the roadbed is ensured to have no turf, tree roots and accumulated water, and the foundation of the original ground is ensured to be compact and flat, the pit treatment is thorough and has no potential quality hazard; the construction of the project of clearing and leveling the surface of the area adopts the combined operation of an excavator, a loader, a bulldozer and a road roller, and the manual cooperation and the transportation construction of a dump truck.
3. The construction method of the filling roadbed of the high-speed railway in the soft soil area according to the claim 2, characterized in that the specific construction process flow of the step (1) is as follows:
preparing the position and elevation of a red line by a measurer according to a construction drawing, and clearly marking the position and elevation with lime; the organic soil, planting soil and garbage in the red line range are cleaned by matching an excavator, a loading and unloading machine, a bulldozer and a dump truck; field management and technicians determine the position of the red line pile; for the areas of the field plots where disputes are not solved, indicating and marking;
carrying out safety education training on constructors; after the roots are dug out in the waterless area in the field, temporary drainage and water retaining projects must be built firstly before the surface is cleared; in the water-containing area, the accumulated water on the earth surface must be dredged and drained and the waterproof and drainage work in rainy season must be done; building a 1-meter high-water-retaining soil cofferdam in a watery area, and digging tree roots after the construction;
cutting or transplanting trees, shrubs and weeds in a field range for cleaning, stacking the cleaned surface soil containing plant roots and humus properly, and uniformly transporting the soil to a spoil area as soil for secondary tillage of the spoil area;
filling and compacting the artificially-formed pits after the removal is finished, and rolling the pits until the specified compactness is achieved; when the surface is cleaned, a temporary drainage measure is made, the original surface accumulated water is drained, and the underground water leakage in the basic range is strictly treated according to the design requirement;
and (4) sampling and performing foundation test detection after surface cleaning and leveling, and performing construction of the next procedure after the requirement is met.
4. A construction method of a high-speed railway fill subgrade in a soft soil area according to claim 1, characterized in that in the step (2), the rigid pile is in the form of a pre-stressed pipe pile prefabricated in a factory or a cast-in-situ bored pile;
drilling the cast-in-situ pile by adopting a rotary drilling rig, and forming the pile by pouring concrete underwater after mud protecting walls;
the specific construction process flow is as follows:
pile position lofting and rechecking: performing pile position lofting and rechecking by using a total station or RTK according to the datum point to ensure that the pile position deviation meets the standard requirement;
pile foundation in-place and centering: after confirming the pile position of the pile to be constructed without errors, positioning a drilling machine according to the preset pile position, stopping the drilling machine on the hard ground, adjusting mast deviation, ensuring that pile displacement and inclination do not exceed standards, and performing irregular inspection and adjustment in the process of forming holes;
preparing slurry: all the used slurry is high-quality high-plasticity clay premixed in advance, the specific gravity of the stirred slurry is 1.1-1.15, and the slurry is added and purified in time along with the progress of construction; the quality of hole forming and pile forming is ensured;
drilling: during drilling, the drilling speed is mastered according to the soil layer condition, and the lifting speed of the drilling bucket in the hole is strictly controlled; when the hole is drilled to the depth required by the design, the hole depth is measured on site by constructors and supervision engineers together, and the hole depth is used as the basis of the final hole depth;
slag removal of a drilling machine: after the drilling hole reaches the designed depth, slightly lifting the drilling tool, and cleaning sediments at the bottom of the hole by using the drilling tool;
manufacturing and placing a reinforcement cage: the reinforcement cage is manufactured on site, the stirrups and the main reinforcements are firmly bound at each node, and the reinforcement cage is slowly placed to prevent collision with the hole wall;
placing a catheter: the conduit is connected by a phi 250 screw fastener, each section is 2.5m in length, and the bottom tube is 4.5m in length; assembling and pressure testing are carried out before use, and the water pressure during the test is at least 1.5 times greater than the water depth in the well; the guide pipe is placed by adopting a truck crane, and the bottom of the guide pipe is placed to be 50cm away from the bottom of the hole;
pouring concrete: pre-mixed commercial concrete is adopted, and a pump is adopted to directly connect the pre-mixed commercial concrete into a collecting hopper; the concrete is firstly poured by adopting enough concrete reserve quantity, so that the guide pipe is embedded into the concrete surface for more than 1m at one time; the concrete has good workability, the slump is controlled to be 16-22 cm, and the slump of the concrete for each pile is subjected to sampling inspection for not less than 1 time;
and carrying out next procedure construction after the construction detection of the cast-in-situ bored pile is qualified.
5. The construction method of the high-speed railway fill subgrade in the soft soil area according to the claim 1, characterized in that in the step (3), according to different geological conditions, a treatment measure of a cement mixing pile or a multi-directional mixing cement mortar pile semi-rigid composite foundation is adopted to reinforce the soil body between the slope toe of the embankment and the load influence line, and before reinforcement, construction can be carried out by ensuring that the strength of the rigid pile in the load influence line range reaches the design requirement so as to avoid influencing the strength and the verticality of the rigid pile; the construction sequence of the composite foundation is carried out from the rigid pile to the slope toe of the embankment;
the stirring pile adopts two-spraying four-stirring steps, and the construction process flow comprises the following steps: the pile driver is in place and leveled; stirring and drilling to a designed depth; spraying slurry, stirring and lifting; lifting to a pulp stopping surface; re-stirring and sinking to the designed depth; lifting and stirring the gunite to a gunite stopping surface; closing the stirring machine, and moving the pile machine;
and after the construction of the composite foundation is finished, detecting the integrity, uniformity, unconfined compressive strength, single-pile bearing capacity and composite foundation bearing capacity of the pile body.
6. A construction method of a high-speed railway fill subgrade in a soft soil area according to claim 5, characterized in that in the step (5), the semi-rigid composite foundation is 40cm of cushion layer thickness, and the rigid piles are 60cm of cushion layer thickness;
one layer of high-strength geogrid is sandwiched between the semi-rigid pile broken stone cushion layers, two layers of high-strength geogrids are sandwiched between the rigid pile broken stone cushion layers, the maximum particle size of the broken stone cushion layers is not more than 30mm, the mud content is not more than 5%, grass roots and garbage impurities are not contained, the broken stone cushion layers are rolled and compacted, the compaction degree is not less than 96%, and the porosity is not more than 23%; the geogrid is a polypropylene bidirectional geogrid, the breadth is not less than 5.0m, the diameter of meshes is 80-120 mm, the longitudinal and transverse yield tensile strength is not less than 100kN/m, and the longitudinal and transverse elongation is not more than 10%; when the geogrid is laid, the geogrid is straightened and leveled, the webs are aligned with one another, and the overlapping length is not less than 15 cm.
7. A construction method of a filling roadbed of a high-speed railway in a soft soil area according to the claim 6, wherein in the step (5), the cushion layer quality inspection comprises layered construction quality inspection and engineering quality acceptance; the quality and quality standard of the layered construction enable the cushion layer to reach the compactness required by the design, and the compaction coefficient lambda c reaches 0.94-0.97;
adopting a penetrometer and heavy dynamic sounding inspection to the cushion layer, and inspecting the construction quality of the cushion layer by using the penetration degree corresponding to the designed compaction coefficient as a standard through field tests;
the compaction coefficient can be detected by adopting a sand irrigation method and an irrigation method; when a penetrometer or dynamic sounding is adopted to test the construction quality of the cushion layer, the distance between test points of each layer is less than 4 m; when the bearing capacity of the cushion layer is tested by adopting a load test in completion acceptance, each single project is not less than 3 points; the number of inspection points is determined according to the unit engineering quantity or the engineering area.
8. The construction method of the filling roadbed of the high-speed railway in the soft soil area according to the claim 1, wherein in the step (6), the light foam concrete construction process flow is as follows: metering the ingredients; preparing foam by adopting a foaming agent; adding water and an auxiliary agent into the cement and uniformly stirring; stirring by adopting foam concrete stirring equipment; pouring in situ according to the design gradient requirement; surface smoothing; arranging an expansion joint; and (5) overall maintenance.
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