1.1 Lay EPS insulation layer to prevent roadbed freezing damage
Building roads in permafrost areas will change the local environment, causing the permafrost to melt, causing serious diseases and even road damage. Traditional frost damage prevention and control methods, such as matting, salt injection, soil replacement, and slag spreading, are not very effective.
Because the bubbles on the inner wall of the EPS material are closed and not connected to each other, they have low water absorption and good frost resistance, ensuring that they still have good thermal insulation properties even when soaked. The EPS board insulation subgrade test (1990) on the Kunlun Mountain section of the Qinghai-Tibet Highway showed that the 6cm EPS insulation layer can reduce the heat flow from the surface to the deep layer, reduce the downward movement of the underground upper limit of the permafrost layer, slow down the freezing and thawing of the permafrost layer, and maintain The stability of the line structure reduces deformation. The research results have been promoted and applied in the Chuma River approach, the Hongliang River Bridge approach, and the old hot spring area. Judging from the progress of the project,
1.2 Reduce subgrade settlement and prevent subgrade instability
When an embankment is built on a soft soil foundation, due to the high density of ordinary filler, the additional stress on the foundation caused by its own weight is relatively large, which often results in uneven settlement of the roadbed and excessive settlement. Because EPS has the characteristics of low density and ultra-light weight, after filling to a certain depth, it can effectively reduce the self-weight of the embankment, reduce the additional stress on the foundation, reduce the settlement of the soft soil embankment, and improve the stability of the foundation. . Filling an EPS embankment with a height of 10m is approximately equivalent to the load of a low soil embankment with a height of 10cm, which greatly reduces the load on the embankment. so,
EPS construction does not require special machinery and can be constructed manually. It is fast and suitable for disaster relief. It is more suitable for sites where large machinery is difficult to use. It can be processed and cut on site to adapt to the terrain requirements of the site. In the Taizhou section of the K42+650~K42+800 section of the first phase of the Ningbo-Taizhou-Wenzhou Expressway, in August 1998, the soft soil roadbed collapsed due to rapid filling, and the ground arch height was 60cm. Due to the tight construction schedule and the site being restricted by National Highway 104 and peripheral factory buildings, EPS lightweight materials were ultimately used to fill the embankment. There are 6 layers at the thickest part and 1 layer at the thinnest part, with a total volume of 7295 cubic meters. In October of the same year, the dam was completed. Since the end of 1998,
1.3 Prevent the bridge head from jumping and reduce the lateral displacement of the bridge abutment
Due to the particularity of the bridge head (the junction between the bridge abutment and the roadbed), the quality of the roadbed filling construction is difficult to control, and the structural differences between the bridge abutment and the embankment make the bridge head prone to uneven settlement, which has a great impact on road life, driving comfort and safety. big. Reducing or controlling uneven settlement of bridge heads is a difficult problem in soft soil foundation embankment construction. Because EPS is extremely light in weight, it can be used as bridgehead filler to effectively reduce settlement differences. At the same time, due to its good independence, it can greatly reduce the lateral pressure of the embankment on the bridge abutment and reduce the lateral displacement of the bridge abutment.
The Xintianwei Bridge (center bridge number K57+010) on both sides of the Huzhou section of the Hangzhou-Nanjing Expressway was displaced during the backfilling process of the bridge abutment. According to the construction period and foundation treatment conditions, the EPS light embankment treatment plan is adopted. The length of the EPS embankments at both ends of the Xintianwei Bridge is about 22m, and the filling thickness has changed from 6 layers (layer thickness 48.5cm) to 1 layer starting from the bridge abutment, with a total volume of 2332m3. The EPS project started construction in March 2000 and was completed in May. It was completed and opened to traffic at the end of the same year. At present, the asphalt concrete pavement is in good condition and there is no jumping phenomenon on the bridge section.
1.4 Build vertical embankments
In the construction of steep mountainous slope areas and urban roads, the characteristics of EPS such as strong self-reliance and small lateral deformation can be used to build vertical embankments to reduce land occupation and increase aesthetics. For highway project expansion, EPS can not only reduce uneven settlement caused by the splicing of old and new highways, but can also build steep slopes and even vertical slopes, which is very helpful in reducing secondary land acquisition and saving valuable land resources.
1.5 Minimize the impact on underground or adjacent buildings
The uneven settlement of the upper soil mass and the soil mass on both sides of the rigid structure buried under the embankment often produces excessive additional pressure on the top of the structure. The vertical earth pressure coefficient can reach 1.2. When the soil layer is higher, that is, the top of the structure There is stress concentration, which can lead to cracking and damage of underground structures. Using EPS instead of the top filling of the structure can improve the stress distribution on the structure, and the earth pressure coefficient can be reduced to 0.3.