阅读说明：本技术 一种防冰雪的桥面控温方法 (Bridge deck temperature control method for preventing ice and snow ) 是由 但汉成 方旺林 王旭东 陈钰晶 尹海红 洪晓宇 何振华 柏格文 于 2021-01-25 设计创作，主要内容包括：本发明提供一种防冰雪的桥面控温方法,所述桥面控温方法包括在桥面的混凝土面板上方铺设流通地下水的管网,所述流通地下水的管网设置在沥青铺装层之下,且所述沥青铺装层中含有相变材料,所述相变材料包括正十四烷和正十八烷的混合物,且所述混合物中正十四烷的用量大于正十八烷的用量,所述桥面控温方法包括在微寒季节通过相变材料放热而自发温控,不消耗外部能量；在极寒季节地下水循环和相变材料共同作用,有效抑制结冰,并在一定程度上实现桥面除冰,提高行车安全。此外,在炎热季节,地下水的流动能有效降低路面温度,降低沥青路面车辙的产生。总的来说,本发明提供的方法效果很好,环保且成本低廉。(The invention provides an anti-ice and snow bridge deck temperature control method, which comprises the steps of paving a pipe network for circulating underground water above a concrete panel of a bridge deck, wherein the pipe network for circulating the underground water is arranged below an asphalt pavement layer, the asphalt pavement layer contains a phase-change material, the phase-change material comprises a mixture of n-tetradecane and n-octadecane, the using amount of the n-tetradecane in the mixture is more than the using amount of the n-octadecane, the bridge deck temperature control method comprises the steps of spontaneous temperature control through heat release of the phase-change material in a cold season without consuming external energy; under the combined action of underground water circulation and the phase change material in extremely cold seasons, the icing is effectively inhibited, the bridge deck deicing is realized to a certain extent, and the driving safety is improved. In addition, in hot seasons, the flow of underground water can effectively reduce the temperature of the pavement and reduce the generation of tracks on the asphalt pavement. In general, the method provided by the invention has the advantages of good effect, environmental protection and low cost.)

1. The bridge deck temperature control method for preventing ice and snow is characterized by comprising the steps of paving a pipe network for circulating underground water above a concrete panel of a bridge deck, wherein the pipe network for circulating the underground water is arranged below an asphalt pavement layer, the asphalt pavement layer contains a phase change material, the phase change material comprises a mixture of n-tetradecane and n-octadecane, the using amount of the n-tetradecane in the mixture is more than that of the n-octadecane, and the bridge deck temperature control method comprises the steps of performing spontaneous temperature control through heat release of the phase change material in a cold season without consuming external energy; under the combined action of underground water circulation and the phase change material in extremely cold seasons, the icing is effectively inhibited, the bridge deck deicing is realized to a certain extent, and the driving safety is improved.

2. The method of claim 1, wherein the n-tetradecane is 80-90 wt% and the n-octadecane is 10-20 wt% of the mixture.

3. The method according to claim 1, wherein the phase change material further comprises silica sol, the amount of the silica sol is 0.5 to 1.2 times the amount of the tetradecane, and the mass fraction of the silica sol is 20% or more.

4. The method according to claim 1, wherein the phase change material is used in an amount of 1 to 10 wt%, preferably 2 to 5 wt% in the bituminous paving layer.

5. The method of claim 1, wherein the network of pipes through which the groundwater flows comprises a serpentine, circuitous arrangement of heat exchange pipes.

6. The method according to any one of claims 1 to 5, characterized in that n-tetradecane and n-octadecane are mixed uniformly, the mixture is mixed uniformly with silica sol, phase change material powder is prepared by a sol-gel method, and the phase change material powder is added into raw materials of an asphalt pavement according to a grading particle size, so that the asphalt pavement containing the phase change material is obtained.

Technical Field

The invention relates to the field of road maintenance, in particular to a bridge deck temperature control method for preventing ice and snow.

Background

The road and bridge deck ice condensation seriously harms the driving safety of vehicles, the reduction and inhibition of the road and bridge deck icing are important tasks of the current maintenance department, and the factors of traffic safety, energy consumption, economic benefits, environmental protection and the like are comprehensively considered, so that the road and bridge deck snow and ice melting technology becomes an indispensable component in the road maintenance work, and has very important practical significance.

The existing bridge deck deicing technology mainly comprises manual clearing, mechanical deicing, deicing by a snow melting agent, microwave deicing, electric heating deicing, deicing by an anti-freezing ice additive and the like. Wherein, the manual removal is manual snow removal, which has high labor cost, low efficiency, poor environment and traffic influence. The mechanical deicing is performed by using imported equipment, domestic equipment generally only has a single snow removing or deicing function, and the close adhesion effect of the device parts and the road surface is not good enough. The snow-melting agent is used for deicing by, for example, scattering inorganic salts, and the inorganic salts scattered in the method are easy to pollute the environment, pollute underground water and vegetation and corrode the bottom of the vehicle wheel; when organic salts are scattered to remove ice, related research is still to be perfected; if other snow-melting agents such as urea are added, the application is not wide because of the high cost. And the microwave deicing has low utilization rate due to complex principle and higher cost. Electrical heating de-icing is a significant disadvantage due to maintenance difficulties and excessive energy consumption. Deicing with anti-icing additives may result in reduced pavement performance and failure of the additive life.

In addition, for example, Marly et al pass heating steel pipes through the reinforcing mesh of the bridge deck pavement layer, and connect the temperature sensor and the electrical element devices such as the contactor to form the intelligent temperature-control anti-freezing bridge deck. And a temperature is set, so that the bridge deck is automatically opened when the temperature is lower than the temperature by 2 ℃ and is automatically closed when the temperature is higher than the temperature, and the temperature control effect of the bridge deck is achieved. However, the heating steel pipes are penetrated in the reinforcing mesh, so that the construction difficulty is low, the construction period is influenced, and the parallel operation cannot be realized; and the subsequent operation cost is high, and a large amount of electric energy needs to be consumed. And Yang donate chapter, etc. have designed a kind of deck structure of preventing frostbite, utilize the high-strength seamless steel tube to encapsulate the phase change material of phase change temperature 4.53 ℃, as the deck functional layer of preventing frostbite specifically. The functional layer can play a certain role in transversely reinforcing the bridge deck while delaying the icing of the bridge deck. However, the phase-change material in the scheme has limited heat release, and the effect is poor if the bridge surface is long in low-temperature time. In addition, the phase-change latent heat of the phase-change material is used as a heat source by Humanin and the like, the phase-change material is applied to the pavement ice and snow removing technology by a hot melting method, the material composition of a heating material system, the packaging mode of the phase-change material and the structure of a phase-change material heating body are determined, and a pavement heating and snow melting material system test piece is prepared. The experimental research shows that: the temperature field distribution of the heating material system can be improved and the temperature regulation and control can be realized through the energy slow release effect generated by the phase change of the phase change material. In addition, the invention patent application CN202010434074.1 discloses a preparation method of tetradecane expanded graphite low-temperature phase-change cement mortar, which relates to the field of building materials, wherein the finally produced low-temperature phase-change cement mortar has the advantages of phase-change temperature regulation, long service cycle, environmental protection, no toxicity and the like, and the specific scheme is as follows: the phase-change cement paste comprises the following components in parts by mass: 100 parts of cement, 140-300 parts of sand, 30-60 parts of water and 10-30 parts of phase change material; the phase-change material takes expanded graphite as a carrier matrix and tetradecane as a phase-change substance; the low-temperature phase change cement mortar produced by the preparation method of the tetradecane expanded graphite low-temperature phase change cement mortar provided by the invention has the advantages of phase change temperature regulation, long service cycle, environmental protection, no toxicity and the like; the low-temperature phase change cement slurry produced by the preparation method of the tetradecane expanded graphite low-temperature phase change cement mortar can achieve the effect of delaying ice condensation or snow melting and deicing, can prevent ice condensation on a road surface, effectively solves the traffic safety problem of the ice condensation road surface, avoids traffic accidents as far as possible, and improves the road traffic capacity and the operation benefit. The invention patent application CN201810568384.5 relates to a composite phase-change heat storage asphalt pavement material and a preparation method thereof, and belongs to the technical field of functional pavement materials. The invention deposits silica gel by ammonia water, freezes the silica gel by liquid nitrogen, promotes the pore expansion of the silica gel by utilizing the expansion in the process of converting water phase into solid phase, then dries the silica gel in a freezing environment, further expanding the silica gel by sublimation of solid phase water to prepare expanded silica gel with a space network structure, absorbing tetradecane serving as a phase-change heat storage material in pores by utilizing the capillary force of the expanded silica gel to compact the gel so that the gel can still keep a stable shape without leakage when reaching a phase-change temperature, thereby obtaining the composite phase change material with good shaping effect by taking tetradecane as the phase change material and silica gel as the carrier matrix, increasing the bulk density of the asphalt mixture, and the void ratio and the mineral aggregate void ratio of the asphalt mixture are reduced, the phase-change heat storage asphalt mixture with controllable mixing amount is formed, the environmental temperature change is actively responded, and the heat storage and cooling effects are realized. However, the phase-change cement mortar or phase-change asphalt mixture prepared by the methods has limited heat release, and the effect is poor if the bridge deck is long in low-temperature time, so that the method is only suitable for cold regions.

Therefore, there is a need in the art for a new method of controlling temperature of a bridge deck to prevent ice and snow.

Disclosure of Invention

The invention designs a scheme for controlling the temperature of the bridge deck by adopting a combination technology of underground water circulation and phase-change asphalt mixture aiming at the phenomenon that the bridge deck is frozen in winter.

Therefore, the invention provides an ice and snow prevention bridge deck temperature control method, which comprises the steps of paving a pipe network for circulating underground water above a concrete panel of a bridge deck, wherein the pipe network for circulating the underground water is arranged below an asphalt pavement layer, the asphalt pavement layer contains a phase change material, the phase change material comprises a mixture of n-tetradecane and n-octadecane, the using amount of the n-tetradecane in the mixture is more than the using amount of the n-octadecane, and the bridge deck temperature control method comprises the steps of self-temperature control through heat release of the phase change material in a cold season without consuming external energy; under the combined action of underground water circulation and the phase change material in extremely cold seasons, the icing is effectively inhibited, the bridge deck deicing is realized to a certain extent, and the driving safety is improved.

In a specific embodiment, the n-tetradecane is 80-90 wt% and the n-octadecane is 10-20 wt% of the mixture.

In a specific embodiment, the phase change material further comprises silica sol, the amount of the silica sol is 0.5 to 1.2 times of the amount of the tetradecane, and the mass fraction of the silica sol is 20% or more.

In a specific embodiment, the phase change material is used in an amount of 1 to 10 wt%, preferably 2 to 5 wt%, in the asphalt pavement.

In a specific embodiment, the pipe network for circulating groundwater comprises a serpentine and circuitous arrangement of heat exchange pipes.

In a specific implementation mode, n-tetradecane and n-octadecane are mixed uniformly, the mixture is mixed uniformly with silica sol, phase change material powder is prepared by a sol-gel method, and the phase change material powder is added into raw materials of an asphalt pavement layer according to the grading particle size, so that the asphalt pavement layer containing the phase change material is obtained.

The underground water circulation and phase-change material temperature control system established by the invention at least has the following beneficial effects:

1. the invention adopts underground water to prevent ice and snow, is a natural resource with the temperature of 5-10 ℃ generally, and can be used without heating. The invention combines the underground water circulation and the spontaneous heat release of the phase-change material, and can play a better role in preventing ice and snow on the bridge deck. Specifically, the underground water pipe network mainly solves the temperature problem in the bridge deck structure layer, the asphalt pavement layer containing the phase change material mainly solves the temperature problem on the upper surface of the bridge deck, and the temperature control of the underground water pipe network and the asphalt pavement layer is combined to control the temperature so as to cope with long-term low temperature and extreme weather of the bridge deck.

2. Further, the phase change material used in the present invention includes n-tetradecane and n-octadecane, and the phase change material has a phase change temperature closer to the freezing temperature and a longer life span than the phase change material using n-tetradecane alone. In addition, the pavement performance is not reduced but slightly improved after the scheme of the invention is used.

3. In the scheme of the invention, the temperature is controlled spontaneously by the phase-change material in the cold season, and external energy is not consumed; under the combined action of underground water circulation and the phase change material in extremely cold seasons, the icing is effectively inhibited, the bridge deck deicing is realized to a certain extent, and the driving safety is improved. In addition, underground water can effectively reduce the temperature of the pavement in hot seasons, and the generation of tracks on the asphalt pavement is reduced.

4. The scheme of the invention has the advantages of environmental protection, high efficiency and low cost.

And (3) environmental protection: the underground water circulation bridge deck pavement adopts natural heat energy, the organic phase-change material has no biological toxicity and corrosivity, and the influence on the road environment is small under the long-term use condition.

High efficiency: the invention can realize the two-stage anti-freezing function in cold seasons and the pavement cooling function in hot seasons, and plays an important role in controlling the anti-freezing function of the pavement of high-safety grade road sections such as highway bridge surfaces and the like.

The cost is low: the phase-change asphalt mixture has low cost, is only added once in the construction period, and does not need secondary investment in subsequent use; the underground water pipeline of the bridge deck temperature control system can be operated in parallel in the construction period, and only simple and convenient overhaul and maintenance are needed subsequently.

Drawings

FIG. 1 is a flow chart of the construction of bridge deck pavement according to the method of the present invention.

Detailed Description

The underground water circulating part in the bridge deck temperature control system specifically comprises a bridge deck internal pipe network part and an underground water taking and ground water storage part. When the system works, constant temperature water is extracted from the underground, impurities are removed through filtering and sedimentation in the sedimentation tank, certain pressure is applied to the constant temperature water, the constant temperature water flows through a pipe network inside the road surface to exchange heat for the road surface structure, so that the aim of controlling temperature and deicing is fulfilled, and finally the constant temperature water flows into the underground again through the water outlet. The main components of the underground water circulation deicing system comprise: circulating water pump, cistern, sedimentation tank, valve, pipe network system. The structure of the ground water circulation system can be seen in applicant's prior patent CN 201621102942.1. In the invention, the underground water circulating pipe network is embedded between the concrete bridge deck and the asphalt pavement layer. Therefore, the bridge deck structure is not influenced, and the bridge deck structure can be close to the outer surface of the bridge deck to obtain a good heat exchange effect. In the invention, the underground water transportation pipelines are arranged at two sides of the bridge and are responsible for conveying constant-temperature underground water and recovering the heat-exchanged underground water. The laying mode of the embedded pipeline network adopts a snake-shaped arrangement mode so as to improve the heat exchange efficiency of fluid and the bridge floor.

The phase-change material used in the invention comprises the following steps: in a first step, a phase change material powder is prepared. And step two, preparing a phase-change asphalt mixture.

The first step is as follows: the preparation method of the PCMs (phase change materials) comprises the following steps:

170 parts of n-tetradecane and 30 parts of n-octadecane, mixing, placing in a constant temperature water bath at 60 ℃, and stirring at a high speed for 20min until the mixture is uniformly mixed. The obtained blend solution is placed in a low-temperature box at the temperature of 8 ℃ for 2 hours, and the blend is observed not to have the solid crystallization phenomenon, namely the mixing effect is good. The mixture was poured into 160 parts of 30% silica sol and stirred in a thermostatic water bath at 60 ℃ for 15 min. And cooling the formed composite gelled substance to room temperature, putting the cooled composite gelled substance into a 0 ℃ thermostat, preserving the heat for 20 hours, taking the cooled composite gelled substance out, and grinding the cooled composite gelled substance into powder with the particle size of 0.1-0.5 mm, thus finishing the preparation of the PCMs.

The second step is that: the preparation method of the phase-change asphalt mixture comprises the following steps:

and (3) replacing fine aggregates with the same grain size with the PCMs prepared in the first step by an isometric method, and adding the PCMs into the mixture. The asphalt pavement layer AC-16 is taken as an example. Basalt aggregates, limestone mineral powder, asphalt, PCMs and other raw materials are selected according to the design gradation, and the gradation dosage is shown in Table 1.

TABLE 1

As can be seen from Table 1, the 0.3mm, 0.15mm and 0.075mm gears in the table total 11%, and since the proportion of PCMs added is 3%, 27.3% of each of the 0.3mm, 0.15mm and 0.075mm gears are replaced by PCMs, i.e. the 0.3mm, 0.15mm and 0.075mm gears replace 1.37%, 0.68% and 0.95% of the total amount of PCMs with the same particle size. The design of the proportions after replacement is shown in Table 2, and others are not shown in agreement with the components in Table 1. The PCMs are added at one time when the aggregates are mixed, and the asphalt and the mineral powder are added after the aggregates are fully dried and mixed for subsequent construction operation.

TABLE 2

In the invention, because the groundwater resource is rich, the constant temperature water tank can be regarded as a huge constant temperature water tank, and the water temperature of the groundwater cannot be obviously changed in the process of extracting the groundwater and reinjecting the groundwater, so that the extracted groundwater temperature can be always kept in a very ideal state. And the underground water is constant temperature liquid and is hardly connected with the temperature reduction of the earth surface, if the sudden extremely cold or long-term low temperature condition exists, the flow speed of the underground water in the pipeline is accelerated, and the method can be realized through an algorithm program. The invention can not cause the problem of insufficient heat exchange time and heat exchange quantity at the bridge deck because of accelerating the flow velocity of the underground water. In the present invention, even if a pipe through which groundwater circulates is broken due to disaster ineffectiveness, etc., the leakage does not affect the environment.

The phase change material used in the present invention includes a mixture of n-tetradecane and n-octadecane. The phase transition temperature of the single-phase n-tetradecane is 5.8 ℃, and the phase transition temperature of the single-phase n-octadecane is 27.7 ℃. The phase transition temperature of the system in the alkane composite material is lower than the lowest temperature of any single phase, namely, the phase transition temperature of the composite phase transition material prepared by fully mixing n-tetradecane and n-octadecane is lower than 5.8 ℃, and the phase transition temperature is lower as the n-octadecane is added more. In the prior art, there are many examples of the use of single-phase n-tetradecane for phase-change anti-freezing materials. However, there is a problem that the phase transition temperature of n-tetradecane (5.8 ℃) is much higher than the freezing temperature of water (0 ℃ for pure water), and the phase transition is a continuous process, and actually the phase transition phenomenon occurs in a temperature range, so that the n-tetradecane starts to undergo phase transition at 7 to 8 ℃. This leads to a problem that when the temperature drop is not significant (e.g., 5 ℃), the phase change material releases heat prematurely before the water does not freeze, and if the temperature is subsequently lowered (e.g., to 1 ℃), the phase change material no longer releases heat, which is equivalent to the failure of the phase change material, and the road surface water freezes as it is. If the bridge deck or pavement water contains more impurities, the freezing point can be obviously lowered (possibly to-2 ℃), and the phase change system of the tetradecane can be more functionally disabled.

In order to avoid the function failure of the phase-change material system, the phase-change temperature of the phase-change material is controlled to be about 3 ℃ above the freezing temperature of water in the method. The phase transition temperature of the PCMs obtained by the compound formula of 80-90 wt% of n-tetradecane and 10-20 wt% of n-octadecane is about 3 ℃, and the phase transition time cannot cause function failure too early and cannot cause road surface water to be frozen too late.

In addition, there are many methods for adding a phase change material to an asphalt mixture, a direct blending method (directly blending with the mixture), a porous material adsorption method (physically adsorbing on a porous material carrier), a sol-gel method (method employed in the present invention), a microcapsule method (wrapping with microcapsules), and the like. The PCMs prepared by the method have good effect and can not generate phase separation and supercooling phenomena. The silica sol used in the sol-gel method has extremely stable chemical properties, the silica sol material is cheap, the whole preparation process of the phase-change asphalt mixture is short, and the realizability is good.

The key point of the invention is the combination of the phase-change material and the anti-icing of the groundwater flowing in the pipeline. The method has the advantages that the method simply uses the phase-change material and the underground water for flowing heat exchange, which are the prior art, but the phase-change material is not beneficial to long-term use and is particularly not suitable for extremely cold weather with long duration; and the underground water flow is used for heat exchange, so that the problems of short-time small cooling can be solved, and energy is consumed for pumping underground water. The method of the invention can realize spontaneous temperature control through the phase-change material in the cold season without consuming external energy. Under the combined action of underground water circulation and the phase change material in extremely cold seasons, the icing is effectively inhibited, the bridge deck deicing is realized to a certain extent, and the driving safety is improved. In addition, in hot seasons, the flow of underground water can effectively reduce the temperature of the pavement and reduce the generation of tracks on the asphalt pavement. In general, the method provided by the invention has the advantages of good effect, environmental protection and low cost.

The above examples are only for clearly illustrating the technical solutions of the present invention, and are not intended to limit the embodiments of the present invention. Any other changes or modifications of the equivalent technical features without changing the basic idea and essence of the present invention shall fall within the protection scope of the claims of the present invention.