A subgrade structure of high liquid limit soil treated by steel slag

Abstract

This utility model discloses a roadbed structure for treating high liquid limit soil with steel slag, including a bottom high liquid limit soil layer, an upper layer of high liquid limit soil to be improved, a first conductive layer between the high liquid limit soil layer and the high liquid limit soil to be improved layer, a steel slag layer above the high liquid limit soil layer, and a second conductive layer above or within the steel slag layer. The steel slag layer used in this utility model for improving high liquid limit soil does not need to be mixed with the high liquid limit soil layer; it can be laid in layers, which is economical. An electric field is used to drive the hydrated cations in the steel slag into the high liquid limit soil layer, accelerating the improvement process. This promotes the use of steel slag to treat high liquid limit soil in highway engineering.

Description

Technical Field

[0001] This utility model belongs to the field of highway construction technology, specifically relating to a roadbed structure for treating high liquid limit soil with steel slag. Background Technology

[0002] In highway engineering, soil with a liquid limit exceeding 50% is classified as high liquid limit soil. High liquid limit soil is unsuitable for direct embankment construction and requires special treatment when used for roadbed construction.

[0003] Steel slag can be used to treat soils with high liquid limit to reduce their liquid and plastic limits. The mechanism is that steel slag contains a large number of high-valence cations, which migrate to the surface of soil particles with high liquid limit and can form hydrated cations, thereby reducing the double electric layer thickness of the soil particles with high liquid limit and thus reducing their liquid and plastic limits.

[0004] Conventional techniques for improving high-liquid-limit soils using steel slag employ two methods: one involves crushing the steel slag and uniformly mixing it with the high-liquid-limit soil, then compacting it; the other involves filling the high-liquid-limit soil with steel slag, forming an interlayered steel slag-high-liquid-limit soil subgrade structure. The uniform mixing method requires specialized mixing equipment and a certain mixing time, increasing project costs. The layered filling method, however, eliminates the need for mixing, significantly shortening the project time and saving costs. However, the layered filling relies on rainfall to leach high-valence cations from the steel slag into the high-liquid-limit soil layer, a slow process that makes it difficult to complete the treatment of high-liquid-limit soils during construction. However, if measures can be taken to accelerate the migration of high-valence cations from the steel slag into the high-liquid-limit soil layer, the treatment process can be expedited. Utility Model Content

[0005] The purpose of this invention is to provide a new roadbed structure for treating high-liquid-limit soils by steel slag, which can accelerate the migration of high-valence cations from steel slag into high-liquid-limit soil layers.

[0006] To achieve the above objectives, the technical solution of this utility model is as follows: A roadbed structure for treating high liquid limit soil with steel slag includes a bottom high liquid limit soil layer, an upper high liquid limit soil layer to be improved, a first conductive layer between the high liquid limit soil layer and the high liquid limit soil layer to be improved, a steel slag layer above the high liquid limit soil layer to be improved, and a second conductive layer above or within the steel slag layer.

[0007] In a further improvement, the first conductive layer is electrically connected to the cathode of the DC power supply, and the second conductive layer is electrically connected to the anode of the DC power supply.

[0008] In a further improvement, the first conductive layer is a cathode steel wire mesh.

[0009] In a further improvement, the second conductive layer is an anode steel wire mesh.

[0010] Further improvements include a high liquid limit soil layer with a thickness of 20-30 cm and a steel slag layer with a thickness of 3-5 cm.

[0011] Compared with the prior art, this utility model has the following advantages: The steel slag layer of this utility model for improving high liquid limit soil does not need to be mixed with the high liquid limit soil layer, and can be spread in layers, which is economical.

[0012] 2. An electric field is used to drive hydrated cations in steel slag into the high liquid limit soil layer, thereby accelerating the improvement process of the high liquid limit soil.

[0013] These three utility models promote the use of steel slag to treat high-liquid-limit soils in highway engineering. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of this utility model.

[0015] Among them, the high liquid limit soil layer 1, the high liquid limit soil layer to be improved 2, the cathode wire mesh 3, the steel slag layer 4, and the anode wire mesh 5. Detailed Implementation

[0016] The technical solutions in the embodiments of this utility model will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0017] The inventors discovered that the migration rate of cations in a liquid can be accelerated under the action of an external electric field. Therefore, the inventors proposed that by placing an anode in the steel slag layer and a negative electrode in the high liquid limit soil, the electric field force can be used to promote the hydration of cations to leave the steel slag layer and enter the high liquid limit soil layer, thereby accelerating the treatment process of high liquid limit soil.

[0018] Specifically, the steel slag-high liquid limit soil subgrade structure consists of the following interlayered structural units: from top to bottom, anode wire mesh + steel slag + high liquid limit soil layer to be improved + cathode wire mesh + high liquid limit soil layer.

[0019] Steel slag and high liquid limit soil layers are designed and constructed according to conventional procedures and methods.

[0020] The thickness of the steel slag layer is not less than 3~5cm; the thickness of the high liquid limit soil layer (2) to be improved is 20~30cm.

[0021] Both the anode and cathode wire mesh are powered by direct current, with a DC power supply voltage of 24~36V.

[0022] The treatment principle of layered steel slag filling for improving high liquid limit soil subgrade is as follows: Anode steel wire mesh is set in the steel slag layer, and cathode steel wire mesh is set in the high liquid limit soil. Then, a DC power supply is electrically connected to form a directional electric field. Under the driving force of the electric field, hydrated cations can generate directional electromigration in the soil, accompanied by a series of electrochemical processes such as adsorption and aggregation, and ion exchange, thereby reducing the liquid and plastic limits of the high liquid limit soil.

[0023] Treatment time calculation method: Voltage V between the positive and negative electrodes, thickness d (thickness of the improved high liquid limit soil layer + steel slag), actual electric field strength (considering the tortuous pore path): τ is the tortuosity factor (usually τ≥1), which represents the multiple by which the actual migration path of the ion is longer than the geometric distance d.

[0024] The electromobility of cations in solution is μ (unit: m² / (V·s)), and the migration velocity of ions in an electric field is: (2) Ion migration time t The soil porosity n (pore volume ratio) is such that ions need to pass through the medium thickness d, but the actual path is extended to τd due to the tortuous nature of the pores, and the migration time is: According to standard parameters: The thickness of the high liquid limit soil layer in the subgrade to be improved is 0.2 m, the thickness of the steel slag layer is 0.05 m, and d = 0.25 m; the porosity n = 0.15; the voltage V = 24 V; the typical electromigration value of cations in solution is: μ Ca2+ ≈6.2×10 −8 m 2 / (V⋅s)μ (25°C, dilute solution), with a tortuosity factor τ of 2.58. The calculations show the cations moving from the anode to the cathode. t It will take 78 hours.

[0025] From the above theory, we can also determine that the key factors affecting ion migration are: 1) Porosity n: The lower the porosity (n→0), the more the migration time increases (t∝1 / n).

[0026] 2) Voltage V: Time is inversely proportional to voltage; increasing the voltage can shorten the migration time.

[0027] 3) Medium thickness d: time versus d 2 Proportional to thickness, increasing thickness will significantly prolong the migration time.

[0028] After the roadbed construction is completed, pavement and traffic engineering construction are still required. There are more than 6 months between the completion of roadbed construction and the opening to traffic, which is much longer than the required 78 hours. Therefore, the treatment of high liquid limit soil roadbed can be completed quickly during the construction period, saving construction time.

[0029] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0030] Furthermore, it should be noted that the scope of the methods and systems in the embodiments of this utility model is not limited to performing functions in the order shown or discussed. It may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0031] The embodiments of the present utility model have been described above. However, the present utility model is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present utility model without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of the present utility model.

Claims

1. A roadbed structure for treating high liquid limit soil with steel slag, characterized in that, The structure includes a high liquid limit soil layer (1) at the bottom, and a high liquid limit soil layer (2) to be improved above the high liquid limit soil layer (1); a first conductive layer is laid between the high liquid limit soil layer (1) and the high liquid limit soil layer (2) to be improved; a steel slag layer (4) is laid above the high liquid limit soil layer (2), and a second conductive layer is laid above or inside the steel slag layer (4).

2. The roadbed structure for treating high liquid limit soil with steel slag as described in claim 1, characterized in that, The first conductive layer is electrically connected to the cathode of the DC power supply, and the second conductive layer is electrically connected to the anode of the DC power supply.

3. The roadbed structure for treating high liquid limit soil with steel slag as described in claim 1, characterized in that, The first conductive layer is a cathode steel wire mesh (3).

4. The roadbed structure for treating high liquid limit soil with steel slag as described in claim 1, characterized in that, The second conductive layer is an anode steel wire mesh (5).

5. The roadbed structure for treating high liquid limit soil with steel slag as described in claim 1, characterized in that, The thickness of the high liquid limit soil layer (2) to be improved is 20~30cm; the thickness of the steel slag layer (4) is 3~5cm.

Images