Summary of the invention
The object of the invention is to: the area that the present invention be directed to high and cold, high altitude localities change of current variable field ground and carrying track is large, length is long, easily produce crack, a kind of high and cold, high altitude localities change of current variable field ground and carrying track method for controlling crack are provided, solve high and cold, high altitude localities at present, impact due to natural environment, make change of current variable field ground and carrying track produce crack and affect the technical problem of workmanship, thereby can effectively solve above-mentioned problems of the prior art.
The object of the invention realizes by following technical proposals: a kind of high and cold, high altitude localities change of current variable field ground and carrying track method for controlling crack, comprise following construction method:
One, between road surface and roadbase, establish binder course: binder course thickness is that 130-150mm, 5% cement stabilized grading crushed stones form semi-rigid layer;
Two, drainage measure: carrying track is established the gutter of drainage grade and track grade coordination, that is, the carrying track that is parallel to orbiting valve Room direction is not established gutter, establishes drainage grade be not more than 0.3% gutter perpendicular to the track grade of orbiting valve Room direction;
Three, the shrinkage joint that setting space is 3-5m in carrying track concrete pavement, and in concrete base layer, increase the cracking resistance steel mesh reinforcement that diameter is thin, spacing is close, the longitudinal reinforcement of described cracking resistance steel mesh reinforcement is located under surface layer end face in 1/3 thickness, and transverse reinforcement is positioned under longitudinal reinforcement;
Four, in carrying track concrete pavement, press 1.2kg/m
3mix anti-crack fiber;
Five, carrying track foundation towing pad steel buried plate adopts the circular steel plate that diameter is 1000-1200mm, and opens the circular hole that diameter is 350-400mm.
Preferably, to inhomogeneous ground, binder course adopts the mattress layer that thickness is 300mm as a kind of, and its material selection particle diameter is less than one or more mixing in the medium sand, coarse sand, graded sand and stone of 20mm.
As further preferred, the cracking resistance steel mesh reinforcement that described diameter is thin, spacing is close refers to that adopting two-way concrete slab diameter and spacing is the steel mesh reinforcement that Ф 4100mm-Ф 6100mm, protective layer thickness are 15mm~25mm.
As further preferred, described anti-crack fiber is selected polypropylene fibre.
As further preferably, to building complete concrete, before concrete final set, start to adopt curing agent insulated curing, by the even spary of curing agent at concrete external surface.
As further preferably, in winter construction process, at maintaining test block with same condition intensity record, reach regulation and require time then form removal.
As further preferred, the curing time of winter construction is greater than 14 days.
Compared with prior art, beneficial effect of the present invention: the present invention has proposed a kind of effectively preventing control method to high and cold, high altitude localities change of current variable field ground and carrying track crack, within the extent of injury can being controlled to certain scope by this effective control method, thereby guarantee workmanship; Solve the problem that change of current variable field ground and carrying track crack have a strong impact on workmanship and the rear place of construction overall aesthetics.
The specific embodiment
In order to make object of the present invention, technical scheme and advantage clearer, below in conjunction with embodiment, the present invention is further elaborated.Should be appreciated that specific embodiment described herein, only in order to explain the present invention, is not intended to limit the present invention.
Disclosed all features in this manual, or the step in disclosed all methods or process, except the speciality and/or step of mutual repulsion, all can combine by any way, unless narration especially, all can be replaced by other equivalences or the alternative features with similar object,, unless narration especially, an embodiment in a series of equivalences of each feature or similar characteristics.
High and cold, high altitude localities change of current variable field ground and a carrying track method for controlling crack, comprise following construction method:
One, between road surface and roadbase, establish binder course: binder course thickness is that 130-150mm, 5% cement stabilized grading crushed stones form semi-rigid layer;
Two, drainage measure: carrying track is established the gutter of drainage grade and track grade coordination, that is, the carrying track that is parallel to orbiting valve Room direction is not established gutter, establishes drainage grade be not more than 0.3% gutter perpendicular to the track grade of orbiting valve Room direction;
Three, the shrinkage joint that setting space is 3-5m in carrying track concrete pavement, and in concrete base layer, increase the cracking resistance steel mesh reinforcement that diameter is thin, spacing is close, the longitudinal reinforcement of described cracking resistance steel mesh reinforcement is located under surface layer end face in 1/3 thickness, and transverse reinforcement is positioned under longitudinal reinforcement;
Four, in carrying track concrete pavement, press 1.2kg/m
3mix anti-crack fiber;
Five, carrying track foundation towing pad steel buried plate adopts the circular steel plate that diameter is 1000-1200mm, and opens the circular hole that diameter is 350-400mm.
In addition: to inhomogeneous ground, binder course adopts the mattress layer that thickness is 300mm, its material selection particle diameter is less than one or more mixing in the medium sand, coarse sand, graded sand and stone of 20mm.
The cracking resistance steel mesh reinforcement that described diameter is thin, spacing is close refers to that adopting two-way concrete slab diameter and spacing is the steel mesh reinforcement that Ф 4100mm-Ф 6100mm, protective layer thickness are 15mm~25mm.
Described anti-crack fiber is selected polypropylene fibre.
To building complete concrete, before concrete final set, start to adopt curing agent insulated curing, by the even spary of curing agent at concrete external surface.
In winter construction process, at maintaining test block with same condition intensity record, reach regulation and require time then form removal.
The curing time of winter construction is greater than 14 days.
embodiment:
The morning and evening temperature difference on high and cold, Converter Station at High Altitude change of current variable field ground is large, takes following engineering measure in the design of change of current variable field ground and carrying track and construction:
One, between road surface and roadbase, establish binder course: binder course is that 150mm is thick, 5% cement stabilized grading crushed stones semi-rigid layer; Semi-rigid layer can discharge surface layer shrinkage stress, and inhomogeneous ground is adopted to mattress, and square basic unit avoids basis to cross macrorelief, the desirable 300mm of mattress layer thickness, and its material can be selected medium sand, coarse sand, graded sand and stone etc., and maximum particle diameter is 20mm.
Two, the drainage measure on track square adopts the gutter that drainage grade and track grade are coordinated, and avoids the erosion of rainwater to ground.
Three, the shrinkage joint that in the concrete pavement of track square, setting space is 3-5m, improves constraints, and concrete pavement can be stretched, and overcomes excessive thermal stresses.In the concrete base layer of change of current change square, increase cracking resistance steel mesh reinforcement and reduce crack.
Four, in the concrete pavement of track square, mix anti-crack fiber, in the present embodiment, adopt polypropylene fibre.
Five, carrying track foundation towing pad steel buried plate adopts circular steel plate and opens circular hole, and its effect can be eliminated buried plate distress in concrete around.
In addition, if meet winter construction, also need to take following winter construction measure:
1, stipulate rational striking time;
2, the proper extension concrete heat-insulating cover time:
From thermal stresses viewpoint, concrete heat-insulating should reach following requirement:
Prevent concrete inside and outside temperature difference and concrete surface gradient, prevent external crack;
Prevent concrete supercool, manage to make concrete construction period minimum temperature to be not less than the equilibrium temperature of concrete operating period as far as possible.
Prevent that old concrete is excessively cold, to reduce the constraint between New-old concrete.
3, brushing curing agent maintenance.
engineering construction example:
The most regional height above sea level in Lhasa surpasses 4000 meters, is one of city that height above sea level is the highest in the world, belongs to the semiarid monsoon climate in temperate zone, plateau, and day and night temperature is large, 28 ° of C of the highest temperature, the subzero 14 ° of C of the lowest temperature.Therefore, at Construction in Lhasa current conversion station, will exist on high and cold, high altitude localities change of current variable field ground and the problem in carrying track crack.
The change of current of Lhasa ± 400kV current conversion station becomes high and cold, high altitude localities, and sooner or later the temperature difference is large, therefore, need in the design of change of current variable field ground and carrying track and construction, take following engineering measure:
First, between road surface and roadbase, establish binder course.Concrete measure is: binder course is 150mm, thick 5% cement stabilized grading crushed stones semi-rigid layer, and semi-rigid layer can discharge surface layer shrinkage stress.The change of current becomes under carrying track foundation, in case of inhomogeneous ground all adopts mattress layer, regulates the differential settlement on basis between different ground situations, and total settlement and differential settlement are controlled in an allowed band, avoids the generation of crack due to settlement.
Secondly, drainage measure is taked on track square, avoids the erosion of rainwater to ground; Specifically, the carrying track that is parallel to the valve Room, track square direction is not established slope, perpendicular to the track grade of the valve Room, track square direction, is not more than 0.3%; Track square drainage grade and track grade are coordinated, and have both met water vent and have met the needs that the change of current becomes carrying track installation planeness.
For underground structure concrete, backfill, reduces the generation in crack as early as possible.
The 3rd, the shrinkage joint that in the concrete pavement of track square, setting space is 4.2m, improve constraints, and, in the concrete base layer of change of current change square, increase cracking resistance steel mesh reinforcement and reduce crack, cracking resistance steel mesh reinforcement adopts two-way Ф 4100~Ф 6100, and cracking resistance steel mesh reinforcement protective layer thickness is 15mm~25mm; And, being set to of steel mesh reinforcement: longitudinal reinforcement is located under surface layer end face in 1/3 thickness range, and transverse reinforcement is positioned under longitudinal reinforcement.
Because track square and the concrete reinforcement ratio of carrying track are extremely low, reinforcement is very little on concrete thermal stresses impact, in temperature, under the not too high and condition of stress lower than yield limit, the properties of steel is stable, and irrelevant with stress state, time and temperature.In addition, the linear expansion coefficient of steel and concrete linear expansion coefficient differ very little, and very little internal stress only occurs between the two when variations in temperature.Because the modulus of elasticity of steel is modulus of elasticity of concrete 7 ~ 15 times, when inner concrete stress reaches tensile strength and ftractures, the stress of reinforcing bar will be no more than 100 ~ 200kg/cm
2, therefore, the appearance of wanting to utilize reinforcing bar to prevent fine cracks in concrete is very difficult; But the crack after reinforcement in structure generally just becomes, and number is many, spacing is little, hierarchy structure is less, when the thin and spacing of the diameter of reinforcing bar is close, better to improving the effect of cracking of reinforced concrete.
In addition, in the concrete pavement of track square, mix anti-crack fiber.Usually can there is thin and shallow crack in concrete pavement surface, track square; wherein great majority belong to shrinkage crack; although this crack is generally all more shallow; but it still has a certain impact to the intensity of structure and durability; therefore; in Practical Project, at surface layer, mix anti-crack fiber and can avoid preferably surperficial microscopic checks.
In addition, carrying track foundation towing pad steel buried plate adopts circular steel plate and opens circular hole.Engineering practice proof towing pad steel buried plate adopts circular steel plate, adopts square plate at four jiaos of stress crackings that produce before can avoiding.
Finally, if meet while constructing in the winter time, need to conscientiously take winter construction measure, stipulate rational striking time, proper extension concrete heat-insulating cover time, and the maintenance of brushing curing agent.
To high and cold, high altitude localities concrete brushing curing agent maintenance, main purpose is the temperature and humidity condition that keeps suitable, to reach the effect of two aspects, makes on the one hand concrete avoid the invasion and attack of unfavorable temperature, humidity distortion, prevents harmful shrinkage and drying shrinkage.On the one hand cement aquation is carried out smoothly, to reaching intensity and the anti-crack ability of design, suitable temperature and humidity conditions is to be mutually related, and concrete Insulation has the effect of moisturizing.Take, after above measure, can prevent the generation in crack.
Up to the present,, there is not obvious crack in complete 2 years so far of current conversion station square, Lhasa, track construction.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any modifications of doing within the spirit and principles in the present invention, be equal to and replace and improvement etc., within all should being included in protection scope of the present invention.