Concealed small-span cantilever rigid frame construction method

Abstract

The invention relates to the field of road construction, and particularly discloses a construction method of a concealed small-span cantilever rigid frame. The small-span cantilever steel structure is applied to high-speed railway roadbed construction, the pile foundation structure penetrates through the upper arch rock layer and is inserted into the stable rock body, effective supporting can be provided for an upper structure, the mode that the pier column and the cantilever steel structure are disengaged from or separated from the rock body is adopted, a force transmission medium between the upper arch rock body and the structure is isolated, and the construction efficiency is improved. The influence of upward arching of the rock mass on the upper structure is fundamentally eradicated, upward arching of the rail of the high-speed railway is avoided, and it is guaranteed that the high-speed railway can run at a high speed for a long time.

Description

Technical Field

[0001] The invention belongs to the technical field of road construction, and in particular relates to a method for constructing a concealed small-span cantilever rigid frame. Background Art

[0002] At present, my country's railway development momentum is rapid, an efficient railway network has been built, and the speed of railway transportation is constantly increasing. Due to the high operating speed of high-speed railways, high requirements are placed on the smoothness of the line and strict requirements are placed on the degree of roadbed deformation. Roadbed arching is a problem that continues to plague transportation engineering construction.

[0003] Currently, a lot of research has been conducted on the causes of arch deformation of high-speed railway roadbeds. The reason may be that the roadbed contains expansive soil, and the expansive substances in the expansive soil will cause a dramatic expansion in volume when they come into contact with water. It may also be that under suitable conditions of temperature, humidity and salinity, cement-improved soil fillers react with sulfates to form expansive crystals such as calcium aluminate and silica gypsum, which will also cause the roadbed to expand.

[0004] In order to reduce the possible harm caused by road diseases such as roadbed expansion, it is necessary to change the roadbed structure and replace the construction method to avoid roadbed arching. Summary of the invention

[0005] The object of the present invention is to provide a method for constructing a concealed small-span cantilever rigid frame to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for constructing a concealed small-span cantilever rigid frame comprises the following steps:

[0008] S1. Excavation of pile holes: excavating weakly weathered rock layers by drilling and coring to form pile holes;

[0009] S2. Hole cleaning and steel cage lowering. After the pile excavation is completed, the hole is cleaned, the steel cage is hoisted into place, the steel casing is installed, and the water in the hole is pumped out;

[0010] S3, pour the pile foundation concrete to 30 cm above the bottom of the steel casing, then pour high-strength quick-setting bearing grouting mortar along the outside of the steel casing and wait for one hour;

[0011] S4. Pour pier column concrete into the steel casing to the top of the steel casing, and pour asphalt between the steel casing and the rock wall to the designed elevation of the pier column top;

[0012] S5. Excavate the overlying rock and soil to the top elevation of the pier column, break the pile head, and test the integrity of the pile foundation;

[0013] S6. Excavate the central blind ditch, fill it with gravel wrapped with geotextile, compact and level the excavation surface, and pour concrete into the cantilever slab to empty the sealing layer;

[0014] S7, lay a sand cushion layer and compact it, lay a layer of square timber on the sand cushion layer, and fix the wooden formwork on the square timber;

[0015] S8. Tie up the cantilever slab beam reinforcement, pour the slab beam concrete continuously at one time, remove the sand cushion layer through high-pressure water flow impact to achieve hollowing, construct the cantilever slab upper waterproof layer, fill the graded gravel transition layer in layers and test it, and construct the ballastless track structure after passing the test.

[0016] Preferably, in S1, the steps of implementing the coring method include:

[0017] Use a coring drill to extract a cylindrical core of 150 mm in length along the perimeter of the bored pile design contour to form an outer peripheral free surface, and then break the remaining core into pieces to complete the bored pile excavation.

[0018] Preferably, in S2, when the hole is cleaned, the thickness of the sediment at the bottom of the hole is reduced to less than five centimeters.

[0019] Preferably, in S4, the pier column concrete pouring and asphalt pouring are performed on alternate days.

[0020] Preferably, in S6, the cantilever plate hollow sealing layer is a ten-centimeter-thick C25 fine stone fiber concrete layer.

[0021] Preferably, in S6, a transverse slope of 1.5% is retained during the pouring of the cantilever slab hollow sealing layer.

[0022] Preferably, in S7, the sand cushion layer is laid with a thickness of five centimeters.

[0023] Preferably, in S8, the sand cushion layer is removed after the cantilever plate strength reaches 20 MPa.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention is applied to the high-speed railway roadbed construction by arranging a small-span cantilever steel structure. The pile foundation structure passes through the upper arch rock layer and is inserted into the stable rock mass. It can not only provide effective support for the upper structure, but also adopts the method of hollowing out or separating the pier and the cantilever rigid frame from the rock mass, thereby isolating the force transmission medium between the upper arch rock mass and the structure, fundamentally eliminating the influence of the rock arch on the upper structure, thus avoiding the arch of the high-speed railway track, and ensuring that the high-speed railway can run at a high speed for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a flow chart of the construction method of the present invention;

[0027] Figure 2 It is a structural schematic diagram of the concealed small-span cantilever rigid frame of the present invention;

[0028] Figure 3 Schematic diagram of the pile hole excavation steps of the present invention, a is the arrangement of coring points, b is the drilling of columnar concrete cores by a water-grinding drill, c is the splitting of the middle concrete to take out the slag sample, and d is the pile hole correction;

[0029] Figure 4 It is a schematic diagram of the arrangement structure of the steel casing and the steel cage of the present invention;

[0030] Figure 5 It is a schematic diagram of the pile concrete structure of the present invention;

[0031] Figure 6 It is a schematic diagram of the sand cushion structure of the present invention;

[0032] In the figure: 1. Concrete pile body; 2. Pier; 3. Partition layer; 4. Cantilever slab beam; 5. Graded crushed stone layer; 6. Drill hole; 7. Pile hole; 8. Steel cage; 9. Steel casing; 10. Blind ditch; 11. Sealing layer; 12. Sand cushion layer; 13. Square timber; 14. Wood board. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Example:

[0035] See also Figure 1 - Figure 6 As shown, a method for constructing a concealed small-span cantilever rigid frame specifically comprises the following steps:

[0036] S1, excavation of pile holes 7, excavation of weakly weathered rock layers by coring method to form pile holes 7, the coring method implementation steps include:

[0037] Use a coring drill to take out a cylindrical rock core with a length of 150 mm along the periphery of the bored pile design outline to form a borehole 6. All the boreholes 6 form an outer peripheral free surface. The remaining core part is divided into blocks, and a row of small holes are drilled on the divided rocks. A pneumatic pick is used to excavate the rocks into small pieces and transport them out, thus completing the excavation of the bored pile 7;

[0038] S2, hole cleaning and lowering of steel cage 8. When cleaning the hole, reduce the thickness of the sediment at the bottom of the hole to less than 5 cm. After the pile excavation is completed, the hole is cleaned, the steel cage 8 is hoisted into place by mechanical overall hoisting, and the steel casing 9 is hoisted into place by a truck crane. The steel casing 9 and the steel cage 8 are fixed with hanging rods, and the water in the hole is pumped out;

[0039] S3, pouring pile foundation concrete to 30 cm above the bottom of the steel casing 9 to form a concrete pile body 1, and then pouring high-strength quick-setting bearing grouting mortar along the outside of the steel casing 9, etc. for one hour, and after the grouting mortar solidifies, the outside of the bottom of the steel casing 9 is blocked;

[0040] S4, after the grouting material seals the bottom of the steel casing 9, slowly pour concrete into the steel casing 9 to the top of the steel casing 9, use a vibrator to vibrate during the pouring process to ensure the quality of the concrete pouring, and solidify to form a pier 2. The next day, pour asphalt between the steel casing 9 and the rock wall to the designed elevation of the top of the pier 2 to form a separation layer 3;

[0041] S5. Remove the overlying rock and soil to the top elevation of pier 2 by mechanical excavation, break the pile head by ring cutting method, and test the integrity of the pile foundation;

[0042] S6, excavate the central blind ditch 10, fill it with gravel wrapped with geotextile, compact and level the excavation surface, use C25 fine stone fiber concrete to cast a 10 cm thick sealing layer 11, and leave a 1.5% cross slope during the casting process to facilitate the water below the cantilever plate beam 4 to flow into the central blind ditch 10;

[0043] S7, laying a sand cushion layer 12 with a thickness of five centimeters and rolling and compacting it. Small equipment can be used for construction without excessive compaction. A layer of square timber 13 is laid on the sand cushion layer 12, and a wood board 14 is fixed on the square timber 13;

[0044] S8. Tie up the steel bars of the cantilever slab beam 4, and pour the slab beam concrete continuously at one time to form the cantilever slab beam 4. After the strength of the cantilever slab beam 4 reaches 20Mpa, remove the sand cushion layer 12. Remove the sand cushion layer 12 through high-pressure water impact to achieve hollowing. In the later use process, due to the extremely humid use environment, the square timber 13 and the wood board 14 will all decay within three to five years, which provides a guarantee for the realization of further hollowing. Apply a waterproof layer on the cantilever slab beam 4, fill the graded gravel layer 5 in layers and test it. After passing the test, apply the ballastless track structure.

[0045] The standard parts used in the present invention can all be purchased from the market, and the special-shaped parts can be customized according to the description and the drawings. The specific connection methods of each part adopt conventional means such as mature bolts, rivets, welding, etc. in the prior art. The machinery, parts and equipment all adopt conventional models in the prior art, and the circuit connection adopts the conventional connection method in the prior art, which will not be described in detail here. The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

[0046] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0048] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0049] In the drawings of the embodiments disclosed in the present invention, only the structures related to the embodiments disclosed in the present invention are involved, and other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of the present invention can be combined with each other.

Claims

1. A method for constructing a concealed small-span cantilever rigid frame, characterized in that: The specific steps include: S1. Excavation of pile holes: excavating weakly weathered rock layers by drilling and coring to form pile holes; S2. Hole cleaning and steel cage lowering. After the pile excavation is completed, the hole is cleaned, the steel cage is hoisted into place, the steel casing is installed, and the water in the hole is pumped out; S3, pour the pile foundation concrete to 30 cm above the bottom of the steel casing, then pour high-strength quick-setting bearing grouting mortar along the outside of the steel casing and wait for one hour; S4. Pour pier column concrete into the steel casing to the top of the steel casing, and pour asphalt between the steel casing and the rock wall to the designed elevation of the pier column top; S5. Excavate the overlying rock and soil to the top elevation of the pier column, break the pile head, and test the integrity of the pile foundation; S6. Excavate the central blind ditch, fill it with gravel wrapped with geotextile, compact and level the excavation surface, and pour concrete into the cantilever slab to empty the sealing layer; S7, lay a sand cushion layer and compact it, lay a layer of square timber on the sand cushion layer, and fix the wooden formwork on the square timber; S8. Tie up the cantilever slab beam reinforcement, pour the slab beam concrete continuously at one time, remove the sand cushion layer through high-pressure water flow impact to achieve hollowing, construct the cantilever slab upper waterproof layer, fill the graded gravel transition layer in layers and test it, and construct the ballastless track structure after passing the test.

2. The method for constructing a concealed small-span cantilever rigid frame according to claim 1, characterized in that: In S1, the steps of implementing the coring method include: Use a coring drill to extract a cylindrical core of 150 mm in length along the perimeter of the bored pile design contour to form an outer peripheral free surface, and then break the remaining core into pieces to complete the bored pile excavation.

3. The method for constructing a concealed small-span cantilever rigid frame according to claim 2 is characterized in that: In S2, when the hole is cleaned, the thickness of the sediment at the bottom of the hole is reduced to less than five centimeters.

4. The method for constructing a concealed small-span cantilever rigid frame according to claim 3 is characterized in that: In S4, the pier column concrete pouring and asphalt pouring are carried out on alternate days.

5. The method for constructing a concealed small-span cantilever rigid frame according to claim 4 is characterized in that: In S6, the cantilever slab hollow sealing layer is a ten-centimeter-thick C25 fine stone fiber concrete layer.

6. The method for constructing a concealed small-span cantilever rigid frame according to claim 5, characterized in that: In S6, a 1.5% transverse slope is retained during the pouring of the cantilever slab hollow sealing layer.

7. The method for constructing a concealed small-span cantilever rigid frame according to claim 6 is characterized in that: In S7, the sand cushion layer is laid with a thickness of five centimeters.

8. The method for constructing a concealed small-span cantilever rigid frame according to claim 7 is characterized in that: In S8, the sand cushion layer is removed after the cantilever plate strength reaches 20 MPa.

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