CN111395059B - Design and construction method of light roadbed structure crossing karez - Google Patents
Design and construction method of light roadbed structure crossing karez Download PDFInfo
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- CN111395059B CN111395059B CN202010209782.5A CN202010209782A CN111395059B CN 111395059 B CN111395059 B CN 111395059B CN 202010209782 A CN202010209782 A CN 202010209782A CN 111395059 B CN111395059 B CN 111395059B
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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
- E01B2/006—Deep foundation of tracks
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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
- E03—WATER SUPPLY; SEWERAGE
- E03F—SEWERS; CESSPOOLS
- E03F5/00—Sewerage structures
- E03F5/04—Gullies inlets, road sinks, floor drains with or without odour seals or sediment traps
Abstract
The invention relates to the field of geotechnical engineering, in particular to a light roadbed structure crossing a karez, a design method and a construction method. The light roadbed structure comprises light soil groove bodies and long pile assemblies, each long pile assembly comprises a plurality of long piles, a plurality of short piles are arranged on a foundation between a vertical shaft and the long piles, the depth of the short piles embedded into the foundation is smaller than that of an underground canal, the light soil groove bodies are arranged at the tops of the long pile assemblies, a reinforcing mesh cushion layer is laid at the bottom of each light soil groove body and connected with all the long piles, and the short piles are located below the reinforcing mesh cushion layer. The light roadbed structure crossing the karez ensures that the karez is not influenced by engineering construction and operation under the condition of ensuring the safety and reliability of high-speed railway line engineering, achieves the purpose of undisturbed protection of the karez, saves investment and reduces construction cost.
Description
Technical Field
The invention relates to the field of geotechnical engineering, in particular to a light roadbed structure crossing a karez, a design method and a construction method.
Background
As shown in fig. 1, the karez is a special irrigation system for desert areas, and comprises an underground underdrain 73, wherein the underdrain 73 is communicated with at least two vertical shafts 71, all the vertical shafts 71 are arranged at intervals along the extension direction of the underdrain 73, and a large number of karezs are distributed in the areas of the middle asia, the east asia and the Xinjiang in China.
The karez has the functions of irrigation, drainage, landscape, cultural relics and the like, so that the existing functions of the karez cannot be destroyed by a high-speed railway built above the karez.
At present, the difficulty in building high-speed railways in the karez area is that:
if a bridge or a tunnel is adopted to pass through a karez, the engineering investment is obviously increased, and the economic and social benefits are poor;
secondly, if a common roadbed project is built, the campshed underground channel 73 and the vertical shaft 71 need to be reinforced, but the underground channel 73 is narrow in space and lacks of oxygen, so that manual operation is not facilitated, and the reinforcing effect is difficult to guarantee.
Disclosure of Invention
The invention aims to: aiming at the problems that in the prior art, the roadbed project adopting a bridge or tunnel or pile plate structure passes through a karez, the project investment is obviously increased, and the economic and social benefits are poor; if a common roadbed project is built, the underground channel and the vertical shaft of the karez need to be reinforced, but the underground channel is narrow and anoxic, the artificial operation is not facilitated, and the reinforcing effect is difficult to ensure.
In order to achieve the purpose, the invention adopts the technical scheme that:
the utility model provides a stride across light-duty roadbed structure of karez, includes the light soil cell body and sets up the long pile subassembly on the ground of shaft both sides, every the long pile subassembly includes a plurality of supports that are used for the long pile of light soil cell body, the long pile stretches into the ground, the shaft with be provided with a plurality of stub on the ground between the long pile, the stub buries the degree of depth of ground is less than the degree of depth of underdrain, all the top of long pile is connected with reinforcing bar net bed course, reinforcing bar net bed course top is equipped with the light soil cell body.
According to the light roadbed structure spanning the karez, the long pile components are arranged on the foundations on two sides of the karez and comprise a plurality of long piles for supporting the light soil groove bodies, the long piles extend into the foundations, and the long piles can replace the rock-soil foundations to achieve the purpose of bearing upper loads (including the light soil groove bodies, the track structures on the light soil groove bodies and the train loads), so that the condition that the side walls, the tops of the blind ditches and the side walls of the karez collapse due to the fact that additional loads of the roadbed structure are diffused on the lower foundations is avoided, and the normal use function of the karez is guaranteed;
the shaft with be provided with a plurality of stub on the ground between the long stake, the stub is buried the degree of depth of ground is less than the degree of depth of underdrain, and the stub has replaced the partial ground in underdrain top, makes the ground can bear partial additional load through the replacement effect, can greatly reduced because of the upper portion load direct action on the underdrain top, leads to the destroyed probability of underdrain.
Be equipped with the gap between stub and the reinforcing bar net bed course, perhaps do not connect to avoid the road bed load to act on stub pile top, lead to the stub to bear too big, cause the road bed load to transmit to the underdrain top through the stub, thereby lead to the underdrain to destroy.
Meanwhile, the light soil groove body is arranged at the top of the long pile assembly and used for placing an upper structure (such as a soil packing layer, and an upper track structure is placed on the soil packing layer), and the light soil material on the light soil groove body has the characteristics of low density, high compression resistance, standing upright, attractive appearance and the like, can effectively transmit upper load to the long pile assembly, and greatly reduces the self weight of the long pile assembly, so that the top bearing capacity of the long pile and the short pile is greatly reduced, the size requirements of the long pile and the short pile are reduced, and compared with the method that a bridge or a tunnel is adopted to pass through a karez, the investment is saved, and the construction cost is reduced.
And moreover, the reinforcing mesh cushion layer smoothly transmits the upper roadbed load to the long pile top through the self tensile property, so that the acting force of the roadbed load on the short pile top is greatly reduced, and the probability of damage of the underdrain due to the fact that the upper roadbed load directly acts on the top of the underdrain is greatly reduced.
In conclusion, the light roadbed structure spanning the karez mainly bears the load through the long pile components, protects the existing karez through the short piles, reduces the top bearing capacity of the long piles and the short piles through the light soil groove bodies, ensures that the karez is not influenced by engineering construction and operation under the condition of ensuring the safety and reliability of high-speed railway line engineering, achieves the purpose of protecting the karez without disturbance, saves investment and reduces construction cost.
Preferably, the top of the light soil tank body is filled with a soil filler layer for placing an upper rail structure.
Preferably, a mesh reinforcement cushion layer is arranged at the bottom of the light soil tank body and connected with all the long piles.
Preferably, the short pile and the long pile each comprise a pile-forming lightweight body.
Preferably, the long pile comprises a pile-forming light body.
Preferably, the mesh reinforcement cushion layer comprises a mesh reinforcement and a high-strength composite geomembrane which are connected, the mesh reinforcement is positioned at the bottom of the high-strength composite geomembrane, and the mesh reinforcement is connected with the long piles.
The load of the upper roadbed is smoothly transmitted to the pile top of the long pile through the tensile properties of the reinforcing mesh (main) and the high-strength composite earth work membrane (secondary), so that the load of the roadbed is prevented from acting on the pile top of the short pile. And simultaneously, set up the stub and replaced the partial ground at underdrain top, make the ground can bear partial additional load through the replacement effect, additional load direct action that can avoid reinforcing bar net bed course bending effect to arouse at the underdrain top, the condition that leads to the underdrain to destroy takes place, and the bond bar improves the wholeness of structure in addition, let superstructure load transmit smoothly to the long pile of lower part on, avoid superstructure to produce the eccentric action, the compound geomembrane of excelling in can prevent that the top light soil from leaking thick liquid to following in pouring in the campher well.
Preferably, the upper parts of all the long piles are connected with connecting steel bars, and all the connecting steel bars are fixedly connected with the reinforcing mesh.
The integrality of all long pile structures can be improved through the connecting reinforcing steel bars, the load of the upper structure is smoothly transmitted to the long pile at the lower part, and the eccentric action of the upper structure is avoided.
Preferably, at least two transverse geogrids are arranged on the light soil groove body at intervals in the height direction.
The transverse geogrid ensures the integrity of the light soil tank body and improves the shear resistance and the bending resistance of the light soil tank body.
Preferably, at least two transverse geogrids are arranged in the light body at intervals in the height direction.
Preferably, at least two transverse geogrids are arranged in the U-shaped light soil groove at intervals in the height direction.
The transverse geogrid ensures the integrity of the light soil groove body and the U-shaped light soil groove, and improves the shearing resistance and the bending resistance of the light body and the U-shaped light soil groove.
Preferably, the light soil groove body includes the light body and sets up the U type light soil groove at light body top, open setting in U type light soil groove top, the light body set up in long pile subassembly top, fill in the U type light soil groove and build the soil packing layer.
Sometimes, in the construction process of the high-speed railway, high-strength light soil is needed to be used at the upper part of the light soil groove body, and only ordinary light soil is needed to be used at the lower part of the light soil groove body.
The soil filler layer filled in the U-shaped light soil groove has the function of dissipating dynamic stress of the train and preventing the U-shaped light soil groove or the light body from cracking due to frequent train load.
Preferably, the light body is buried in the ground at the bottom.
Preferably, the short pile and the long pile both comprise a pile-forming light body and a composite reinforcement cage embedded in the pile-forming light body, the composite reinforcement cage comprises a plurality of vertical geogrids arranged at intervals in the circumferential direction and a plurality of annular geogrids arranged at intervals in the vertical direction, and the vertical geogrids are connected with the annular geogrids.
The short pile and the long pile make full use of the tensile capacity of the vertical geogrid, and the annular geogrid plays a role of a stirrup under the action of pile top load, so that the compressive capacity of the pile body is greatly improved, and the probability of pile collapse or pile breakage is reduced.
A design method of a light roadbed structure crossing a karr well comprises the following steps:
s1: establishing a roadbed design model based on the light roadbed structure crossing the karez;
s2: inputting the design parameters of the long pile and the design parameters of the light soil groove body into the roadbed design model to obtain the total weight of the superstructureW z Number of single row long piles transverse to roadbednWherein the upper structure comprises the light soil tank body and an upper track structure;
s3: according to the total weight of the superstructureW z Number of said single row of long piles transversely of the roadbednAnd the number of rows of the long piles outside the short piles at two sides of the axial line of the underdrain along the longitudinal direction of the lineNCalculating the bearing safety factor of the long pileKAnd make the bearing safety factorKThe bearing requirements of the long piles are met;
s4: according to the requirement of the long pile bearing safety factorKAnd obtaining the final design parameters of the light roadbed structure crossing the karez.
The design method of the light roadbed structure crossing the karez combines the characteristics of low density, high compression resistance, upright attractiveness and the like of a light soil material, utilizes a long pile replacement principle and crosses the light roadbed structure of the karez to obtain a roadbed design model, and quickly calculates the total weight of the superstructure according to the roadbed design modelW z Number of single row long piles transverse to roadbednThe reasonability of long pile arrangement is greatly improved, and then the total weight of the upper structure is utilizedW z Number of single row long piles transverse to roadbednCalculating to obtain the bearing safety factor of the long pileKWith a safety factorKAs a measure of roadbed safety，Debugging the roadbed design model, and finally determining the most reasonable design parameters of the light roadbed structure crossing the karez.
Preferably, the roadbed design model specifically comprises:
in the formula (I), the compound is shown in the specification,W z is the total weight of the superstructure in kN;
γis the foundation rock soil heavy weight with the unit kN/m3；γ n1The unit kN/m is the light soil weight3；γ n2The unit kN/m is the weight of the soil packing layer3；dThe diameter of the long pile is unit m;sthe distance between long piles is unit m;lthe length of the long pile is m;Lthe length of the roadbed above the long pile and the short pile along the longitudinal direction of the line is unit m; deltahThe light body is embedded into the foundation in depth of m;Bthe width of the top surface of the light roadbed is in the unit of m;mthe slope rate of the light roadbed side slope;hthe height of the light roadbed is in unit m;bthe thickness of a cantilever of the U-shaped light soil tank is m;h n2the filling thickness of the soil filler layer is m;b 1is the track distribution width, unit m;q 1is the dead weight of the track and has the unit kN/m2；s 1Is the line spacing, in m;q 0is the line-to-line load in kN/m2。
Preferably, the bearing safety factorKThe method specifically comprises the following steps:
in the formula (I), the compound is shown in the specification,W z is the total weight of the superstructure in kN;γis the foundation rock soil heavy weight with the unit kN/m3；γ n1The unit kN/m is the light soil weight3；dThe diameter of the long pile is unit m;lthe length of the long pile is m;Nthe number of the long piles outside the short piles at two sides of the axis of the underdrain along the longitudinal line is counted;nthe number of the single-row long piles along the transverse direction of the roadbed;
preferably, the bearing safety factorKThe bearing requirements of the long piles are met,the method specifically comprises the following steps:
when the content is less than or equal to 1.05KLess than or equal to 1.15, bearing safety factorKThe bearing requirements of the long piles are met;
when in useK<1.05 orK>1.15, adjusting the roadbed design model, and repeating the steps S1-S2 until the calculated bearing safety factorKSatisfies the following conditions: 1.05 ≤K≤1.15。
The invention also discloses a construction method for forming the light roadbed structure crossing the karez, which is characterized by comprising the following steps: comprises the following steps:
a1: surveying an influence ring of a vertical shaft on site, and constructing a short pile drill hole outside the influence ring of the vertical shaft;
a2: sending the composite reinforcement cage into the short pile drilled hole;
a3: injecting light soil into the short pile drill hole until the light soil is filled in the short pile drill hole, and completing short pile construction,
a4: constructing a long pile drill hole outside the short pile;
a5: sending the composite reinforcement cage into the long pile drilled hole;
a6: injecting light soil into the long pile drill holes until the long pile drill holes are filled with the light soil, and embedding connecting steel bars at the pile tops of all the long piles to complete construction of all the long piles;
a7: laying a reinforcing mesh cushion layer on the pile top of the short pile and the pile top of the long pile, and connecting the reinforcing mesh cushion layer with the connecting steel bars;
a8: constructing a light body on the reinforcing mesh cushion layer, and laying geogrids in the light body layer by layer;
a9: constructing a U-shaped light soil groove on the light body, and laying geogrids to the bottom surface of the soil filler layer in layers;
a10: and (4) casting cantilevers at two ends of the U-shaped light soil groove, and filling a soil filler layer to the top surface of the roadbed layer by layer after the cantilevers are solidified.
In the above scheme, the influence circle of the shaft is: and (3) determining the safe distance range between the movable soil operation circle and the vertical shaft, wherein no movable soil construction can be carried out in the influence circle, and the range of the influence circle is obtained by field investigation.
According to the construction method for forming the light roadbed structure crossing the karez, disclosed by the invention, by constructing the short piles and the long piles and matching with the reinforcing mesh cushion layer, most of the upper load is effectively transmitted to the long piles far away from the existing karez, and meanwhile, the short piles close to the karez can enable the foundation to bear part of additional load through replacement, so that the probability of damage to the underdrain due to the fact that the upper load directly acts on the top of the underdrain can be greatly reduced. The construction process is simple, the construction quality is guaranteed, the construction land is greatly saved in the whole construction process, the damage to the ecological environment is reduced, and the design concept of energy conservation and low carbon of a high-speed railway and cultural relic protection is met.
In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:
1. according to the light roadbed structure crossing the karez, the long pile assembly is used for carrying out main bearing, the short pile is used for protecting the existing karez, the light soil groove body is used for reducing the top bearing capacity of the long pile and the short pile, the karez is not influenced by engineering construction and operation under the condition that the safety and the reliability of high-speed railway line engineering are guaranteed, the purpose of protecting the karez without disturbance is achieved, meanwhile, investment is saved, and the construction cost is reduced.
2. According to the light roadbed structure spanning the karez, the roadbed load on the upper part is smoothly transmitted to the long pile top through the tensile properties of the reinforcing mesh (main) and the high-strength composite earth work film (secondary), so that the roadbed load is prevented from acting on the short pile top, and further the roadbed load is prevented from acting on the top of the underground canal, and the underground canal is prevented from being damaged. And the connecting reinforcement improves the wholeness of structure, lets superstructure load transmit smoothly to the long pile of lower part on, avoids superstructure to produce eccentric action, and the compound geomembrane of excelling in can prevent to leak thick liquid to the following karl in the time of the top light soil is pour.
3. According to the light roadbed structure spanning the karez, the short piles are arranged to replace partial rock soil at the top of the underdrain, the foundation can bear partial additional load through the replacement effect, and the situation that the underdrain is damaged due to the fact that the additional load caused by the bending effect of the reinforcing mesh cushion layer directly acts on the top of the underdrain can be avoided.
4. According to the light roadbed structure spanning the karez, the integrity of all long pile structures can be improved through the connecting steel bars, the load of the upper structure is smoothly transmitted to the long piles at the lower part, and the eccentric effect of the upper structure is avoided.
5. According to the light roadbed structure crossing the karez, sometimes in the construction process of a high-speed railway, high-strength light soil is needed to be used at the upper part of the light soil groove body, and only ordinary light soil is needed to be used at the lower part of the light soil groove body.
6. According to the light roadbed structure spanning the karez, the short piles and the long piles fully utilize the tensile capacity of the vertical geogrids, and the annular geogrids play a role of stirrups under the action of pile top load, so that the compressive capacity of a pile body is greatly improved, and the probability of pile collapse or pile breakage is reduced.
7. According to the light roadbed structure spanning the karez, the transverse geogrid ensures the integrity of the light soil tank body, and the shear resistance and the bending resistance of the light soil tank body are improved.
8. The design method of the light roadbed structure crossing the karez combines the characteristics of low density, high compression resistance, upright beauty and the like of light soil materials, utilizes long piles to support main upper load, applies the replacement principle of short piles and the light roadbed structure crossing the karez to obtain a roadbed design model, and quickly calculates the total weight of the upper structure according to the roadbed design modelW z Number of single row long piles transverse to roadbednThe reasonability of long pile arrangement is greatly improved, and then the upper structure assembly is utilizedWeight (D)W z Number of single row long piles transverse to roadbednCalculating to obtain the bearing safety factor of the long pileKWith a safety factorKAs a measure of roadbed safety，Debugging the roadbed design model, and finally determining the most reasonable design parameters of the light roadbed structure crossing the karez.
9. According to the construction method for forming the light roadbed structure spanning the karez, disclosed by the invention, by constructing the short piles and the long piles and matching with the reinforcing mesh cushion layer, most of the upper load is effectively transmitted to the long piles far away from the existing karez, the short piles close to the karez can enable the foundation to bear part of additional load through replacement, and the probability of damage to the underdrain due to the fact that the upper load directly acts on the top of the underdrain can be greatly reduced. The construction process is simple, the construction quality is guaranteed, the construction land is greatly saved in the whole construction process, the damage to the ecological environment is reduced, and the design concept of energy conservation and low carbon of a high-speed railway and cultural relic protection is met.
Drawings
FIG. 1 is a schematic cross-sectional view of a prior art existing karez.
Fig. 2 is a schematic cross-sectional view of a lightweight roadbed structure spanning a karr well according to the invention.
Fig. 3 is a cross-sectional view M-M of fig. 2 of the present invention.
Fig. 4 is a schematic view of the relative positions of the mini-stumps and long-stumps of the present invention and the existing karez.
Fig. 5 is a schematic view showing the connection of the mat reinforcement, the connecting reinforcing bars and the long piles according to the present invention
Fig. 6 is a schematic view of the connection mode of the composite reinforcement cage in the long pile or the short pile and the outlet of the pumping pipe.
Fig. 7 is a schematic view of the construction of a long pile or a short pile of the present invention.
Fig. 8 is a schematic view of the light roadbed structure size marking of the invention.
Fig. 9 is a schematic view of the length dimension L of the lightweight roadbed structure according to the invention arranged along the longitudinal direction of the railway line.
Icon: 1-a long pile assembly; 11-short pile; 12-long piles; 13-a composite reinforcement cage; 131-vertical geogrids; 132-an annular geogrid; 14-piling a lightweight body; 15-a protective layer; 2-reinforcing mesh cushion layer; 21-reinforcing mesh; 22-high-strength composite geotechnical membrane; 23-connecting reinforcing steel bars; 3-a light body; 31-transverse geogrid; 4-U type light soil groove; 5-a soil filler layer; 6-drainage ditch; 7-foundation; 71-a shaft; 72-circle of influence; 73-underdrain; 8-pumping the pipe; 81-ring lock catch; 9-light soil tank body.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings.
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
Referring to fig. 1, 2 and 3, the light roadbed structure crossing the karman according to the embodiment of the invention is characterized in that: the short piles 11 are longitudinally arranged outside the influence ring 72 of the vertical shaft 71 at intervals along the line; the long piles 12 are longitudinally arranged outside the range of the short piles 11 on two sides of the axis of the underdrain 73 at intervals along the line; the reinforcing mesh cushion layer 2 is arranged on the tops of the short piles 11 and the long piles 12; one end of the connecting steel bar 23 is anchored into the upper part of the long pile 12, and the other end is fixedly connected with the steel mesh cushion layer 2; the light body 3 is arranged on the reinforcing mesh cushion layer 2; the U-shaped light soil tank 4 is arranged at the top of the light body 3; the soil filler layer 5 is filled in the U-shaped light soil tank 4; and the drainage ditches 6 are arranged at two sides of the light body 3.
In the scheme, the method comprises the following steps:
as shown in fig. 6 and 7, each of the short pile 11 and the long pile 12 is a composite light pile composed of a pile-forming light body 14 and a composite reinforcement cage 13 embedded therein, the composite reinforcement cage 13 is composed of vertical geogrids 131 arranged at intervals in the circumferential direction and annular geogrids 132 arranged at intervals in the vertical direction, the vertical geogrids 131 and the annular geogrids 132 are intersected and connected into a whole, and quadrilateral meshes are formed between two adjacent vertical geogrids 131 and two adjacent annular geogrids 132; the pile-forming light body 14 is formed by pouring light soil into the drilled hole of the foundation 7 from the composite reinforcement cage 13, and a protective layer 15 is formed between the outer wall of the composite reinforcement cage 13 and the wall of the drilled hole of the foundation 7. Short pile 11 and long pile 12 make full use of geogrid's tensile ability, annular geogrid 132 plays the stirrup effect under the effect of pile bolck load, guarantees that the pile body can provide sufficient compressive capacity, avoids bursting or broken pile to take place.
As shown in fig. 2-4, the short piles 11 and the long piles 12 are arranged in a square shape, the short piles 11 are arranged outside the influence ring 72 of the vertical shaft 71, and the difference between the diameter of the influence ring 72 of the vertical shaft 71 and the diameter of the vertical shaft 71 is not less than 1.5 m; the distance between the bottom of the short pile 11 and the top of the underdrain 73 is not less than 3.0m, no less than 2 rows of short piles 11 are arranged on two sides of the axis of the underdrain 73, and the short piles 11 and the long piles 12 are sequentially constructed from the axis of the underdrain 73 to two sides. The short piles 11 have the function of replacing part of rock soil at the top of the underdrain 73, and the foundation 7 can bear part of additional load through the replacement function, so that the additional load caused by the bending effect of the mesh reinforcement cushion layer 2 can be prevented from being directly applied to the top of the underdrain 73, and the underdrain 73 is damaged. The long pile 12 has the function of replacing the rock-soil foundation 7 to achieve the purpose of bearing upper load, and avoids the additional load of the roadbed structure from diffusing on the lower foundation 7, so that the side wall of the karez shaft 71, the top of the underdrain 73 and the side wall collapse to influence the normal use function of the karez shaft.
As shown in fig. 5, the steel mesh cushion layer 2 is composed of a steel mesh 21 and a high-strength composite geomembrane 22 from bottom to top, and the length of the two ends of the steel mesh cushion layer 2 longitudinally extending out of the light roadbed structure in the line is not less than 1.5 times of the roadbed height. The effect of reinforcing mat bed layer 2 lies in through self tensile properties with upper portion road bed load smoothly transmit to long pile 12 pile bolck, avoids road bed load to act on short pile 11 pile bolck, and then avoids road bed load to act on the closed channel 73 top to lead to the closed channel 73 to destroy. The connecting reinforcement 23 is used to improve the structural integrity, so that the load of the upper structure can be smoothly transferred to the lower long pile 12, and the eccentric action of the upper structure can be avoided.
As shown in fig. 2-3, the light body 3 is poured by using common light soil, and the depth of the bottom of the light body 3 embedded into the foundation 7 is not less than 0.5 m; the U-shaped light soil groove 4 is poured by high-strength light soil, and the thickness of the bottom plate of the U-shaped light soil groove 4 is not less than 1.5 m; and (3) pulling through 1 transverse geogrid 31 at intervals of not less than 0.6m along the height direction of the roadbed. The function of the transverse geogrid 31 is to ensure the integrity of the roadbed structure and improve the shear resistance and the bending resistance of the light-weight body 3 and the U-shaped light-weight soil tank 4.
As shown in fig. 2 and 8, the slope ratio of the light body 3 and the side slope of the U-shaped light soil tank 4 on both sidesmAre consistent, andmnot less than 0.2; the slope rate of the side slopemIs the ratio of the length to the height of the triangular side slope.
The thickness of the soil filler layer 5 in the U-shaped light soil tank 4 is not less than the thickness of the surface layer of the roadbed. The soil filler layer 5 filled in the U-shaped light soil tank 4 has the function of dissipating dynamic stress of the train and preventing the U-shaped light soil tank 4 from cracking due to frequent train load.
Example 2
As shown in fig. 2 to 9, a design method for a light roadbed structure crossing a karr well in embodiment 1 includes the following steps:
determining the severity of 7 rock soil of karez foundation by indoor geotechnical testγUnit kN/m3(ii) a Heavy weight of light soilγ n1Unit kN/m3(ii) a Soil filler layer 5 degree of gravityγ n2Unit kN/m3；
② preliminarily determining the 12 pile diameter of the long piledThe unit m; pile spacing of long piles 12sThe unit m; long pile 12 piles longlThe unit m; light roadbed structure positioned on top of long pile 12 and short pile 11 along longitudinal length of lineL(as shown in fig. 9), the unit m; the number of the long piles 12 arranged outside the short piles 11 at the two sides of the axial line of the underdrain 73 along the longitudinal lineN(as described in fig. 4); the light body 3 is embedded into the foundation 7 to a depth deltahThe unit m;
thirdly, the weight of the light body 3, the U-shaped light soil groove 4, the soil filler layer 5 and the upper track structure is determined by the following formulaW z ：
In the formulaW z The unit kN;Bthe width of the top surface of the light roadbed is in the unit of m;mthe slope rate of the light roadbed side slope;hthe height of the light roadbed is in unit m;bthe cantilever thickness of the U-shaped light soil tank 4 is unit m;h n2the filling thickness of the soil filler layer 5 is m;b 1is the track distribution width, unit m;q 1is the dead weight of the track and has the unit kN/m2；s 1Is the line spacing, in m;q 0is the line-to-line load in kN/m2；
Fourthly, determining the number of the transverse single-row long piles 12 of the roadbed by the following formulan(as depicted in FIG. 4):
determining the safety factor by the following formulaK：
Sixthly, judging the safety coefficient obtained in the fifth stepKWhether the content of the additive meets the requirement that the content is more than or equal to 1.05KA value of ≦ 1.15, ifK<1.05 orK>1.15, adjusting the parameters in the second stepd、s、l、L、N、ΔhRepeating the steps from the third step to the fifth step until the operation is finishedKMeets the requirements.
In the third step, the weight values of the common light soil and the high-strength light soil are the same.
Example 3
As shown in fig. 2 to 9, the present embodiment shows a specific design process of a light roadbed structure crossing a karez: design speed per hour of 300km/h and line spacing of high-speed railway of certain newly-built ballastless tracks 14.8m, and needs roadbed engineering (height)hWidth of =3.5mB=14.6 m) across the karez,through investigation, the width of the underground channel 73 of the karez is 1.5m, the height is 1.0m, the burial depth of the underground channel 73 is 122m, the diameter of the vertical shaft 71 is 1.1m, and the stratum in the section is sandy clay. The light roadbed structure crossing the karez is designed, and the slope rate of the side slope of the light roadbed is measured in the design processmTaking 0.2 of the thickness of the soil filler layer 5h n2Taking a U-shaped light soil tank 4 (the thickness of the bottom plate is 1.5 m) with the thickness of the cantilever at the two ends of the U-shaped light soil tank being 0.5mbAnd (5) paving a CRTS I type slab ballastless track on the top surface of the roadbed at 1.0 m. The design is carried out according to the design method of the invention, which comprises the following steps:
determining the severity of 7 sandy clay on karez foundation by indoor geotechnical testγ=19.5kN/m3Heavy and light soilγ n1=5kN/m3Heavy soil filler layer 5γ n2=21kN/m3；
② preliminarily determining the 12 pile diameter of the long piled=0.5m, 12 pile spacing of long piless=1.1m, long pile 12 pile lengthl=15.0m, length of light roadbed structure arranged longitudinally along the lineL=18 m; the number of rows of the long piles 12 arranged outside the range of the short piles 11 at the two sides of the axial line of the underdrain 73N=6, depth delta of light body 3 put into foundation 7h=1.0m；
Thirdly, determining the weight of the light body 3, the U-shaped light soil groove 4, the soil filler layer 5 and the upper track structureW z ：
=3526.4kN
Fourthly, determining the quantity of the transverse composite light piles of the roadbed
=15
Determining the safety factor of bearing
=1.0899
Sixth, after judgementKMeets the requirements.
The light roadbed structure crossing the karez and the design and construction method have the characteristics of novel structure, safety, reliability, investment saving, simple construction and the like, the design flow and the construction method are clear, the structure can also protect the old karez, greatly save construction land, reduce the damage of ecological environment and meet the design concept of energy saving and low carbon of a high-speed railway and cultural relic protection.
Example 4
As shown in fig. 1 to 3, a construction method for forming the light roadbed structure across the karez according to the embodiment includes the following steps:
the invention also provides a construction method of the light roadbed structure crossing the karez, which comprises the following steps:
firstly, processing the geogrid into a composite reinforcement cage 13 and conveying the composite reinforcement cage to a construction site;
secondly, excavating foundation soil of the light body 3 substrate, constructing short piles 11 around the outer side of an influence ring 72 of the vertical shaft 71, drilling holes, and removing residues at the bottom of the holes, wherein the range of the influence ring 72 of the vertical shaft 71 is obtained by field investigation, and no soil moving construction can be carried out in the influence ring 72. (ii) a
Sleeving the upper end of the composite reinforcement cage 13 into the outer wall of the outlet end of the pumping pipe 8, locking the upper end of the composite reinforcement cage by using an annular lock catch 81, and feeding the composite reinforcement cage 13 into a drill hole;
fourthly, slowly injecting the light soil into the drill hole through the pumping pipe 8 until the drill hole is filled with the light soil, then loosening the annular lock catch 81, pumping out the pumping pipe 8,
fifthly, after the construction of the short pile 11 is finished, the long pile 12 is constructed, the long pile 12 is formed according to the second step to the fourth step, and the connecting steel bar 23 is embedded into the pile top;
sixthly, laying 1 layer of reinforcing mesh 21 and high-strength composite geomembrane 22 on the pile tops of the short piles 11 and the long piles 12, and fixing the connecting reinforcing steel bars 23 and the reinforcing mesh 21;
seventhly, pouring common light soil and high-strength light soil in layers, and laying the transverse geogrids 31 in layers till the bottom surface of the soil filler layer 5;
pouring cantilevers at two ends of the U-shaped light soil groove 4, and filling the soil filler layer 5 to the top surface of the roadbed layer by layer after the cantilevers are solidified.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (7)
1. A design method of a light roadbed structure crossing a karr well is characterized in that: the light roadbed structure of the crossing karr well comprises light soil groove bodies (9) and long pile components (1) arranged on foundations (7) on two sides of a vertical shaft (71), each long pile component (1) comprises a plurality of long piles (12) used for supporting the light soil groove bodies (9), each long pile (12) extends into the foundation (7), a plurality of short piles (11) are arranged on the foundation (7) between the vertical shaft (71) and the long piles (12), the depth of the short piles (11) embedded into the foundation (7) is smaller than that of an underdrain (73), the tops of all the long piles (12) are connected with a reinforcing mesh cushion layer (2), the light soil groove bodies (9) are arranged on the tops of the reinforcing mesh cushion layer (2), each light soil groove body (9) comprises a light body (3) and a U-shaped light soil groove (4) arranged on the top of the light body (3), the top of the U-shaped light soil groove (4) is open, the light body (3) is arranged at the top of the long pile component (1), and a soil filler layer (5) is filled in the U-shaped light soil groove (4);
the design method comprises the following steps:
s1: establishing a roadbed design model based on the light roadbed structure crossing the karez;
s2: inputting the design parameters of the long pile (12) and the design parameters of the light soil tank body (9) into the roadbed design model to obtain the total weight of the superstructureW z The number of single row of long piles (12) transverse to the roadbednWherein the upper structure comprises the light soil tank body (9) and an upper track structure;
s3: according to the total weight of the superstructureW z The number of said single row of long piles (12) in the transverse direction of the roadbednAnd the number of the long piles (12) outside the range of the short piles (11) at the two sides of the axial line of the underdrain (73) in the longitudinal row along the lineNCalculating the bearing safety factor of the long pile (12)KAnd is combined withMake the bearing safety factorKThe bearing requirements of the long pile (12) are met;
s4: according to the bearing safety factor meeting the bearing requirement of the long pile (12)KObtaining the final design parameters of the light roadbed structure crossing the karez;
in the above step, the roadbed design model specifically comprises:
in the formula (I), the compound is shown in the specification,W z is the total weight of the superstructure in kN;
γis the foundation (7) rock-soil heavy weight in kN/m3；γ n1The unit kN/m is the light soil weight3；γ n2The soil filler layer (5) is heavy and has a unit kN/m3；dThe diameter of the long pile (12) is unit m;sthe distance between long piles (12) is unit m;lthe length of the long pile (12) is m;Lthe length of the roadbed above the long pile and the short pile along the longitudinal direction of the line is unit m; deltahThe light body (3) is arranged in the foundation (7) with the depth of m;Bthe width of the top surface of the light roadbed is in the unit of m;mthe slope rate of the light roadbed side slope;hthe height of the light roadbed is in unit m;bthe thickness of a cantilever of the U-shaped light soil tank (4) is unit m;h n2the filling thickness of the soil filler layer (5) is m;b 1is the track distribution width, unit m;q 1is the dead weight of the track and has the unit kN/m2；s 1Is the line spacing, in m;q 0is the line-to-line load in kN/m2。
2. The design method as claimed in claim 1, wherein the mesh reinforcement mat layer (2) comprises a mesh reinforcement (21) and a high-strength composite geomembrane (22) which are connected, the mesh reinforcement (21) is positioned at the bottom of the high-strength composite geomembrane (22), and the mesh reinforcement (21) is connected with the long pile (12).
3. The design method according to claim 2, wherein all the long piles (12) are connected with connecting bars (23) at the upper parts thereof, and all the connecting bars (23) are fixedly connected with the reinforcing mesh (21).
4. The design method according to claim 1, characterized in that at least two transverse geogrids (31) are arranged on the light soil trough body (9) at intervals in the height direction.
5. The design method according to any one of claims 1 to 4, characterized in that the short pile (11) and the long pile (12) each comprise a pile-forming light body (14) and a composite reinforcement cage (13) embedded in the pile-forming light body (14), the composite reinforcement cage (13) comprises a plurality of circumferentially spaced vertical geogrids (131) and a plurality of vertically spaced annular geogrids (132), and the vertical geogrids (131) are connected with the annular geogrids (132).
6. The design method according to claim 1, wherein;
bearing safety factorKThe method specifically comprises the following steps:
in the formula (I), the compound is shown in the specification,W z is the total weight of the superstructure in kN;γis the foundation (7) rock-soil heavy weight in kN/m3；γ n1The unit kN/m is the light soil weight3；dThe diameter of the long pile (12) is unit m;lthe length of the long pile (12) is m;Nthe number of the long piles (12) outside the short piles (11) at two sides of the axis of the underdrain (73) is counted along the longitudinal line;nthe number of the single-row long piles (12) along the transverse direction of the roadbed;
bearing safety factorKThe bearing requirements of the long pile (12) are met, and the method specifically comprises the following steps:
when the number is 1.05≤KLess than or equal to 1.15, bearing safety factorKThe bearing requirements of the long pile (12) are met;
when in useK<1.05 orK>1.15, adjusting the roadbed design model, and repeating the steps S1-S2 until the calculated bearing safety factorKSatisfies the following conditions: 1.05 ≤K≤1.15。
7. A construction method is characterized in that: for forming a light roadbed structure crossing over a karez obtained by the design method according to any one of the claims 1-6, the construction method comprises the following steps:
a1: the method comprises the following steps of (1) surveying an influence ring (72) of a vertical shaft (71) on site, and constructing a short pile (11) drilling hole outside the influence ring (72) of the vertical shaft (71);
a2: sending the composite reinforcement cage (13) into the drilled hole of the short pile (11);
a3: injecting light soil into the drilled holes of the short piles (11) until the drilled holes of the short piles (11) are filled with the light soil, and completing the construction of the short piles (11),
a4: drilling a long pile (12) on the outer side of the short pile (11);
a5: sending the composite reinforcement cage (13) into the drilled hole of the long pile (12);
a6: injecting light soil into the drilled holes of the long piles (12) until the drilled holes of the long piles (12) are filled with the light soil, and embedding connecting steel bars (23) at the pile tops of all the long piles (12) to finish the construction of all the long piles (12);
a7: laying a mesh reinforcement cushion layer (2) on the pile top of the short pile (11) and the pile top of the long pile (12), and connecting the mesh reinforcement cushion layer (2) with the connecting steel bars (23);
a8: constructing a light body (3) on the reinforcing mesh cushion layer (2), and laying geogrids (31) in the light body (3) layer by layer;
a9: constructing a U-shaped light soil groove (4) on the light body (3), and laying geogrids (31) to the bottom surface of the soil filler layer (5) in a layered manner;
a10: and (3) casting cantilevers at two ends of the U-shaped light soil groove (4), and filling a soil filler layer (5) to the top surface of the roadbed layer by layer after the cantilevers are solidified.
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| WO1992021825A1 (en) * | 1991-05-31 | 1992-12-10 | Chichibu Cement Kabushiki Kaisha | Construction method of improving or strengthening ground |
| US6354766B1 (en) * | 1999-02-09 | 2002-03-12 | Geotechnical Reinforcement Company, Inc. | Methods for forming a short aggregate pier and a product formed from said methods |
| US20030118755A1 (en) * | 2001-12-21 | 2003-06-26 | Motz Joseph E. | Filled synthetic turf with ballast layer |
| CN201857619U (en) * | 2010-11-16 | 2011-06-08 | 中铁十局集团第三建设有限公司 | Protective pile foundation |
| CN203487528U (en) * | 2013-09-30 | 2014-03-19 | 中铁二十局集团有限公司 | Underground river karst cave treatment structure for underwater pier drilled pile construction in beaded type karst area |
| CN205874850U (en) * | 2016-02-26 | 2017-01-11 | 中国铁道科学研究院铁道建筑研究所 | Railway soft soil foundation light soil roadbed structure |
| CN206752210U (en) * | 2017-01-12 | 2017-12-15 | 中铁二院工程集团有限责任公司 | A kind of high-speed railway silt, flour sand embankment structure |
| CN206706479U (en) * | 2017-03-20 | 2017-12-05 | 中铁二院成都勘察设计研究院有限责任公司 | A kind of light-duty embankment suitable for deep soft soil foundation |
| CN108330745B (en) * | 2018-02-09 | 2020-06-09 | 上海市城市建设设计研究总院（集团）有限公司 | Implementation method of tramcar assembled under-rail foundation in soft soil area |
| CN208219633U (en) * | 2018-05-07 | 2018-12-11 | 中铁二院工程集团有限责任公司 | A kind of composite reinforced stake construction for resisting ground protuberance |
| CN209178724U (en) * | 2018-06-29 | 2019-07-30 | 中铁二院重庆勘察设计研究院有限责任公司 | A kind of expansive soil foundation Ballast track high-speed railway embankment ruggedized construction |
| CN109487640B (en) * | 2018-10-15 | 2020-11-17 | 西南交通大学 | High-speed railway roadbed reinforcing structure in underdrain development area and construction method |
| CN109440541A (en) * | 2018-11-07 | 2019-03-08 | 中铁二院工程集团有限责任公司 | One kind passing through karez high-speed railway Reinforced subgrade construction and construction method |
| CN209759925U (en) * | 2019-04-10 | 2019-12-10 | 四川省交通勘察设计研究院有限公司 | Assembled roadbed construction system suitable for deep and thick soft foundation |
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