Geomagnetic observation station based on weak magnetism and composite heat preservation and construction method thereof

Abstract

The invention discloses a geomagnetic observation station based on weak magnetism and composite heat preservation and a construction method thereof.The geomagnetic observation station comprises a geomagnetic instrument observation room and a matched recording room, the geomagnetic observation room comprises a foundation and a weak magnetic frame structure arranged on the foundation, and the height of the weak magnetic frame structure is 7-9 m; the recording room comprises a foundation structure, a bearing floor, a double-layer arch shell structure and a composite heat preservation layer, the bottom of the foundation structure makes direct contact with fresh bedrock, the bearing floor is poured to the upper portion of the foundation structure, the double-layer arch shell structure is arranged on the bearing floor and comprises an inner arch shell and an outer arch shell, and a gap is formed between the inner arch shell and the outer arch shell to form an air heat preservation layer; the composite heat preservation layer is laid outside the outer arch shell. By increasing the height of the geomagnetic observation room, introducing the composite thermal insulation layer and the weak magnetic material and combining the overall pouring process, the gradient of the vertical magnetic field is smaller than or equal to 1.5 nT / m, the daily temperature difference of the recording room is controlled within 0.15 DEG C, and the precision of geomagnetic observation data is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of seismic observation, and particularly relates to a geomagnetic observation station based on weak magnetism and composite heat preservation and a construction method thereof. Background Art

[0002] Geomagnetism is an observation-based discipline. Geomagnetic observation data is a precious scientific research resource of the country, and is of great significance and wide application in many fields such as earthquake prediction, earth science, resource exploration, aerospace, transportation and communication, national defense construction, environmental monitoring, space weather, satellite communication, and solar activities. The construction quality of the geomagnetic observation station directly affects the quality of geomagnetic observation data and subsequent research and applications.

[0003] The main task of the geomagnetic observation station is to monitor the distribution and variation law of the global and regional geomagnetic fields, reflect the main characteristics of the geomagnetic field, and provide services for departments such as geophysics, upper atmosphere physics, geophysical exploration, surveying, communication, astronautics, and national defense. Therefore, the construction of a standardized and normalized geomagnetic observation station is a necessary basis for ensuring the production of continuous, reliable, and high-quality observation data.

[0004] Since the main task of the geomagnetic observation station is to monitor the change of the geomagnetic field, the geomagnetic field is a weak magnetic field, the geomagnetic change is very weak, and the basic requirement of geomagnetic observation is that the geomagnetic observation facilities cannot affect the original distribution of the geomagnetic field at the geomagnetic observation point. Site selection is the basis for the construction of the geomagnetic observation station, and various factors such as geology, aeromagnetics, terrain, environment, water supply, electricity, transportation, and hydro-meteorology should be comprehensively considered. According to the Geomagnetic Observation Station Construction Specification (DB / T 9-2004): collect relevant geological maps, and it is advisable to select areas where the strata are close to horizontal, the soil layer is thickly covered, or the base is composed of weak magnetic rocks such as limestone and dolomite. However, in actual construction, it is difficult to select dozens of mu of construction land with strata close to horizontal, the eligible plots are becoming increasingly scarce, and the existing technologies are difficult to solve the construction problems in complex terrains, such as a height difference of 15 meters and thin soil layer coverage. In addition, geomagnetic observation needs to be carried out in as quiet an environment as possible to capture weak geomagnetic signals. Therefore, the site selection of the geomagnetic observation station is one of the key points and difficulties in the current construction of the geomagnetic observation station.

[0005] The construction of traditional geomagnetic observatories often focuses on being sturdy. However, a geomagnetic observatory not only requires sturdiness, but more stringent is that the construction of a geomagnetic observatory must meet the specification requirements that the horizontal and vertical magnetic field gradients within the range of the instrument pier for geomagnetic monitoring in the observatory are ≤ 1.5 nT / m, and also pursue weak magnetism or even "no magnetism" in the geomagnetic observatory. If magnetic materials are used to construct a geomagnetic observatory, these materials will generate their own magnetic fields and introduce additional magnetic field noise, thus interfering with the measurement of the geomagnetic field, resulting in distorted observation data and affecting the observation results. Using non-magnetic materials can effectively reduce this environmental noise, thereby improving the reliability and credibility of the data, which is crucial for applications in fields such as earthquake prediction and geomagnetic research. Therefore, in all technical links such as material selection, processing, transportation, storage, and construction of the geomagnetic observatory, it is necessary to ensure that there is no magnetic pollution, and this requirement poses very high demands on the entire process of site selection and construction of the geomagnetic observatory.

[0006] In addition, there are many precision components inside the geomagnetic observation instruments. These instruments are sensitive to the surrounding geomagnetic environment, temperature, humidity, and air pressure. Especially when the geomagnetic observation instruments operate in locations with large day-night temperature variations, it may directly damage these instruments. Since it is impossible to install an air conditioning system for active temperature control for the geomagnetic observation instruments, currently, the construction of geomagnetic stations at home and abroad is basically carried out underground to ensure temperature control. However, for the geomagnetic observatory located underground, due to the requirements of heat preservation and covering soil, the strength requirements for the building's load-bearing structure are relatively high, and a large amount of steel materials are needed for support, increasing the risk of using non-weak magnetic materials.

[0007] Therefore, it is necessary to establish a ground-based geomagnetic observatory. However, while the design and construction of the ground-based geomagnetic observatory meet the construction specifications of the geomagnetic observatory, it has the characteristics of high construction cost, large technical difficulty, and high operation risk. The large technical difficulty lies in that the construction of the geomagnetic observatory requires both no magnetism and heat preservation. For nearly ten thousand tons of building materials, it is necessary to ensure no magnetic pollution in several technical links such as material selection, processing, transportation, storage, and construction. If there is a slight carelessness in any link, all previous efforts will be wasted. Summary of the Invention

[0008] In order to solve the problems of strong magnetic field interference, large temperature fluctuations, and poor accuracy of geomagnetic observation data existing in the ground-based geomagnetic observatory, the present invention provides a geomagnetic observatory based on weak magnetism and composite heat preservation, which reduces the magnetic field interference during geomagnetic observation, and the daily temperature difference fluctuation in the data recording and processing site is extremely small, ensuring the data accuracy of geomagnetic observation.

[0009] The specific technical solution is as follows:

[0010] A geomagnetic observatory based on weak magnetism and composite heat preservation includes a geomagnetic observation room and a supporting recording room. The geomagnetic observation room includes a foundation and a weak magnetic frame structure arranged on the foundation, and the height of the weak magnetic frame structure is 7 - 9 meters;

[0011] The recording room includes an infrastructure, a load-bearing floor slab, a double-layer arch shell structure, and a composite insulation layer. The bottom of the infrastructure is in direct contact with fresh bedrock, and the load-bearing floor slab is cast on the upper part. A double-layer arch shell structure is provided on the load-bearing floor slab. The double-layer arch shell structure includes an inner arch shell and an outer arch shell, and there is a gap between the inner arch shell and the outer arch shell to form an air insulation layer; the composite insulation layer is laid outside the outer arch shell.

[0012] For the geomagnetic observation room constructed by the present invention, the distance between the observation instrument pier surface and the ground in the geomagnetic observation room is increased. Through physical isolation means and by using the vertical attenuation laws of the magnetic field and temperature, the problem of too high horizontal magnetic field gradient is effectively solved, and the problems of magnetic field interference and human noise during the geomagnetic monitoring process in the above-ground observation room are solved from the root, so that the vertical magnetic field gradient ≤ 1.5 nT / m; for the supporting recording room, the construction uses weak magnetic materials combined with a composite insulation layer to achieve double optimization of magnetic field isolation and temperature stability, so that the daily temperature difference in the recording room does not exceed 0.15 °C, significantly improving the environmental stability of the geomagnetic observation station and the accuracy of geomagnetic observation data.

[0013] Preferably, the weak magnetic frame structure is formed by casting C30 non-magnetic and weak magnetic concrete on the main reinforcement bars.

[0014] The weak magnetic frame is made of C30 non-magnetic and weak magnetic concrete cast on the main reinforcement bars. While ensuring the overall firmness of the frame, the magnetic permeability is significantly reduced for places where magnetic field interference needs to be avoided.

[0015] Preferably, the load-bearing floor slab is a composite plate body formed by casting main reinforcement bars and C30 non-magnetic and weak magnetic concrete.

[0016] Preferably, the main reinforcement bars are copper bars or carbon fiber bars.

[0017] The main reinforcement bars in the weak magnetic frame are used to bear tension. Copper bars or carbon fiber bars are selected to replace traditional steel bars, which have very high tensile strength and can ensure the weak magnetism of the overall building at the same time.

[0018] Further preferably, the main reinforcement bars are carbon fiber bars.

[0019] The tensile strength of carbon fiber bars is usually above 3000 MPa, which is 10 to 15 times that of ordinary steel bars, while the density is only 1 / 7 to 1 / 5 of that of steel bars, having significant advantages in reducing the self-weight of the structure; the lightweight characteristic of carbon fiber bars not only reduces the transportation and installation costs, but also improves the seismic performance and corrosion resistance of the geomagnetic observation station, can maintain performance under repeated loads, and reduces the risk of fatigue failure; and has a small thermal expansion coefficient, reducing the structural stress caused by temperature changes.

[0020] Preferably, the composite insulation layer includes an expanded polystyrene layer, a geogrid, a non-magnetic and weakly magnetic mortar, and a fiberglass protective cover;

[0021] An expanded polystyrene layer is laid on the outer arch shell, fixed by a geogrid, covered with a non-magnetic and weakly magnetic mortar on the surface layer, and then covered with a fiberglass protective cover.

[0022] Expanded polystyrene has a low density, is very convenient during construction and transportation, has a low thermal conductivity, excellent heat insulation performance, can be made into large-sized profiles, has high adaptability to the thin plastering system, and is easy to cut; expanded polystyrene itself does not absorb water and has good moisture-proof performance. Combined with the air insulation layer to form a gradient insulation, and the geogrid fixation inhibits the cracking of the insulation layer.

[0023] A non-magnetic and weakly magnetic mortar is selected as the adhesive, and its magnetic susceptibility is lower than that of conventional mortar to avoid magnetic field interference.

[0024] The fiberglass protective cover can ensure the absence of metals and other magnetic substances, and at the same time, its tensile strength can reach 300 MPa, which is basically equivalent to the tensile strength of steel; it has good waterproofness, will not cause fluid leakage, is corrosion-resistant; combined with the non-magnetic and weakly magnetic mortar, it provides a double barrier to external electromagnetic interference and meets the installation environment requirements of high-precision instrument equipment.

[0025] Preferably, several layers of expanded polystyrene layers and geogrids are laid alternately.

[0026] Further preferably, the thickness of each expanded polystyrene layer is 500 mm.

[0027] Optionally, the total thickness of the laid expanded polystyrene layer is 2000 mm.

[0028] Preferably, the geogrid is prepared from basalt fiber.

[0029] The magnetic susceptibility of basalt fiber ≤ 1×10 -5 SI. After replacing metal materials, it can significantly reduce the background noise of the geomagnetic observatory, and has excellent tensile strength and extreme temperature tolerance, and can reduce the corrosion risk and improve the service life of the geomagnetic observatory.

[0030] The present invention also provides a construction method of a geomagnetic observatory based on weak magnetism and composite insulation, and the construction method includes the following steps:

[0031] Strip the weathered layer at the bottom of the construction area of the geomagnetic observatory until the fresh bedrock is exposed;

[0032] Use concrete to level evenly on the fresh bedrock and tamp it with a vibrating rod to complete the foundation;

[0033] Transport the concrete to a high altitude and complete the construction of several geomagnetic observation rooms by continuously pouring concrete;

[0034] Pour a load - bearing floor slab on other foundations in the construction area, construct a two - layer structure of an inner arch and an outer arch on the load - bearing floor slab, and lay a composite insulation layer on the outer arch shell to complete the construction of the recording room.

[0035] In the construction method provided by the present invention, by using the continuous high - altitude pouring technology of C30 non - magnetic and weakly magnetic concrete, the pouring efficiency and quality are improved, the introduction of magnetic materials is avoided, and the construction of the geomagnetic observatory is made more non - magnetic.

[0036] Preferably, the concrete is transported to a high altitude by a crane cooperating with a tower crane hopper.

[0037] By using a crane cooperating with a tower crane hopper for the high - altitude transportation of concrete, it is ensured that the concrete mixture has good pumpability, can cover a large construction range during construction, can transport the concrete to a certain height without manual pipe laying, improves the quality of building components and construction efficiency, has less environmental pollution such as noise, vibration, and dust, and also avoids the introduction of magnetic materials, making the construction of the geomagnetic observatory more non - magnetic.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] (1) For the ground - based geomagnetic observatory of the present invention, the distance between the observation instrument pier surface and the ground in the geomagnetic observation room is increased, effectively solving the problem of high horizontal magnetic field gradient directly, and fundamentally solving the problems of magnetic field interference, temperature fluctuation, and human noise in the ground - based observation room during the geomagnetic monitoring process, so that the vertical magnetic field gradient ≤ 1.5 nT / m.

[0040] (2) For the construction of the supporting recording room, the use of weakly magnetic materials combined with a composite insulation layer realizes the dual optimization of magnetic field isolation and temperature stability, solves the construction problems of geomagnetic observatory stations in the case of high magnetic susceptibility base and large terrain differences, and the daily temperature difference of the recording room does not exceed 0.15 °C, significantly improving the environmental stability of the ground - based geomagnetic observatory and the accuracy of geomagnetic observation data.

[0041] (3) The construction method provided by the present invention, combined with the overall continuous pouring process, uses a crane cooperating with a tower crane hopper for the high - altitude transportation of concrete, reduces the introduction of magnetism, and significantly reduces the land use and construction costs, having a wide range of application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is the front view of the geomagnetic observation room provided by the present invention.

[0043] Figure 2 It is the sectional view of the recording room provided by the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0044] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples, but the implementation and protection of the present invention are not limited thereto.

[0045] The present invention provides a geomagnetic observation station based on weak magnetism and composite thermal insulation. In actual construction, Figure 1 As shown, the height of the weak magnetic frame structure is 7 to 9 meters. By increasing the height of the building and increasing the distance between the instrument pier and the site, the problem of high horizontal magnetic field gradient is directly and effectively solved.

[0046] When constructing the geomagnetic observatory, the weathered layer at the bottom of the construction area is first removed to ensure that fresh bedrock is exposed. C30 non-magnetic and weak magnetic concrete is poured in the construction area to complete the foundation construction.

[0047] Copper or carbon fiber reinforcement mesh is tied on the foundation. The concrete is transported to high altitude by using a crane and a tower crane hopper to continuously pour the concrete as a whole. The concrete can be poured to a certain height without manual pipe laying. The tower crane hopper uses a thickened manganese steel barrel, which is safe, firm, not easy to deform and corrosion-resistant. The thickened bracket uses an inertial mode to mix more evenly, saving time and efficiency. The discharge design uses a hand-cranked gear gate to accurately discharge the material, which can be quickly moved from one site to another during construction, which is convenient and time-saving. After the entire poured warehouse surface is evenly flattened and filled with concrete, all of them are compacted and compacted using a vibrating rod mechanical vibration method to complete the construction of the geomagnetic observatory. In this way, the construction of several geomagnetic observatories has been completed.

[0048] Construction of a recording room is carried out at another location in the construction area, e.g. Figure 2 As shown, the recording room includes a foundation structure 101, a load-bearing floor 102, a double-layer arch shell structure 103 and a composite insulation layer 104. The composite insulation layer is laid on the outside of the outer arch shell and includes expanded polystyrene 10401, geogrid 10402, non-magnetic weak magnetic mortar 10403 and a fiberglass protective cover 10404.

[0049] At another place in the construction area, first tie a copper reinforcement mesh or a carbon fiber reinforcement mesh, use C30 non-magnetic weak magnetic concrete to continuously cast the whole to form a foundation structure, cast the load-bearing floor slab on the foundation structure, the load-bearing floor slab is a composite slab formed by casting the main reinforcement and C30 non-magnetic weak magnetic concrete, and then tie a copper reinforcement mesh or a carbon fiber reinforcement mesh on the load-bearing floor slab and use C30 non-magnetic weak magnetic concrete to continuously cast the whole to form a double-layer arch shell structure, including an inner arch shell and an outer arch shell, with a 1-meter gap between the inner arch shell and the outer arch shell to form an air insulation layer;

[0050] Use expanded polystyrene layer as the thermal insulation layer material on the outer arch shell. First, lay a 500mm-thick expanded polystyrene layer for wrapping, and then use a basalt geogrid crack-resistant net for reinforcement. Alternately lay the expanded polystyrene layer and the basalt geogrid, with a total of 2000mm-thick expanded polystyrene wrapped. After completing the laying of the thermal insulation material, add a 20mm-thick non-magnetic and weakly magnetic mortar isolation layer, and then use a 10mm-thick fiberglass protective cover for reinforcement on the periphery to complete the construction of the recording room.

[0051] In the design of the recording room, composite thermal insulation technologies such as 2000mm-thick expanded polystyrene are used. The results show that the maximum daily temperature difference of the recording room is 0.13℃. All technical indicators meet the requirements of the "Observation Specification for Geomagnetic Stations". The successful application of this technology is an innovation in the construction technology of geomagnetic observation stations, and at the same time, it also finds an effective way to solve the thermal insulation problem of above-ground projects in high terrain gradient areas.

Claims

1. A geomagnetic observatory based on weak magnetism and composite heat insulation, comprising a geomagnetic instrument observation room and a supporting recording room, characterized in that, The geomagnetic observation room includes a foundation and a weak magnetic frame structure provided on the foundation, and the height of the weak magnetic frame structure is 7 to 9 meters; The recording room includes a foundation structure, a load-bearing floor slab, a double-layer arch shell structure and a composite insulation layer. The bottom of the foundation structure is in direct contact with the fresh bedrock, and the load-bearing floor slab is poured on the upper part. A double-layer arch shell structure is provided on the load-bearing floor slab. The double-layer arch shell structure includes an inner arch shell and an outer arch shell. There is a gap between the inner arch shell and the outer arch shell to form an air insulation layer; the composite insulation layer is laid outside the outer arch shell.

2. The geomagnetic observatory according to claim 1, characterized in that, The weak magnetic frame structure is formed by pouring C30 non-magnetic weak magnetic concrete on the main reinforcement.

3. The geomagnetic observatory according to claim 1, characterized in that, The load-bearing floor slab is a composite plate body formed by pouring the main reinforcement and C30 non-magnetic weak magnetic concrete.

4. The geomagnetic observatory according to claim 2 or 3, characterized in that, The main reinforcement is copper reinforcement or carbon fiber reinforcement.

5. The geomagnetic observatory according to claim 1, characterized in that, The composite insulation layer includes an expanded polystyrene layer, a geogrid, a non-magnetic weak magnetic mortar and a fiberglass protective cover; The expanded polystyrene layer is laid on the outer arch shell and fixed by a geogrid. After the surface layer is covered with non-magnetic weak magnetic mortar, it is then covered with a fiberglass protective cover.

6. The geomagnetic observatory according to claim 5, wherein, Several layers of expanded polystyrene layer and geogrid are alternately laid.

7. The geomagnetic observatory according to claim 6, characterized in that, The thickness of each expanded polystyrene layer is 500 mm.

8. The geomagnetic observatory according to claim 5, characterized in that, The geogrid is obtained by preparing basalt fibers.

9. The construction method of the geomagnetic observatory according to any one of claims 1 to 8, characterized in that, Including the following steps: Strip the weathered layer at the bottom of the construction area of the geomagnetic observatory until the fresh bedrock is exposed; Evenly spread the concrete on the fresh bedrock and tamp it with a vibrating rod to complete the foundation; Transport the concrete to a high altitude and complete the construction of several geomagnetic observation rooms by continuously pouring the concrete; Pour the concrete at another place in the construction area to build the foundation structure, pour the load-bearing floor slab on the upper part, build two layers of structures of the inner arch and the outer arch on the load-bearing floor slab, and lay the composite insulation layer on the outer arch shell to complete the construction of the recording room.

10. The construction method according to claim 9, characterized in that, Transport the concrete to a high altitude by a crane cooperating with a tower crane hopper.

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