Introduction of highway subgrade diseases?

When it comes to the standard cross section of subgrade, the relevant architects are still relatively unfamiliar. What is the basic introduction of highway subgrade? What are the common problems? The following is the basic content of Zhong Da Consulting to sort out highway subgrade diseases for builders. The specific content is as follows:

Through combing the relevant contents, Zhong Da Consulting found that the main contents of the standard cross section of highway subgrade include:

What is subgrade?

Subgrade refers to the belt-shaped structure built as the foundation of pavement according to the location of the line and certain technical requirements, and is the foundation of railways and highways. Subgrade is a linear structure made of earth or stone.

Introduction of highway subgrade diseases;

Highway subgrade diseases mainly include: subgrade subsidence, subgrade sliding along the hillside, fragmentation and collapse, subgrade damage caused by adverse geological and hydrological conditions, etc. The basic overview is as follows:

1, subgrade settlement

Subgrade settlement means that the subgrade surface has a large settlement in the vertical direction, and this settlement is irreversible. This is one of the most common diseases of subgrade. There are many reasons for subgrade settlement, but there are two main ones: compression settlement caused by subgrade itself and settlement caused by foundation.

(1) The settlement caused by subgrade itself is caused by improper selection of subgrade filler, unreasonable filling method, insufficient compactness, and formation of over-wet interlayer inside subgrade embankment. Under the comprehensive action of load, the vertical displacement and deformation of subgrade are caused.

(2) The foundation settlement is due to the existence of soft soil, swamp or loose soil on the original natural foundation, and the bearing capacity of the land foundation is extremely low. Before subgrade filling, the original natural foundation was not treated, and under the action of subgrade self-weight, the subgrade sank or extruded to both sides.

(3) Slope collapse

Subgrade slope collapse is also one of the most common diseases of subgrade, which can be divided into slip and landslide according to the soil type, failure reason and scale of slope. ① Slip: It is formed by a small amount of soil moving down the soil slope. Slip usually refers to the slip of thin soil on the upper surface of slope, which is mainly caused by running water erosion or improper construction. ② Landslide: Landslide is mainly caused by insufficient soil stability. The main reasons for the landslide of embankment slope are large slope, or the foot of the slope is washed away, or the fill layer is improperly arranged.

2. The subgrade slides along the hillside.

When filling subgrade on steep hillside, if the bottom of subgrade is soaked by water, a sliding surface is formed, and the toe of slope is not reinforced. Under the action of various traffic loads of subgrade weight, the original inclined surface of the whole subgrade slides downward, and the whole subgrade is unstable.

3. Division and collapse

Crushing and spalling are the surfaces of weathered rock layers on cutting slopes. Under the alternating action of atmospheric temperature and humidity, the surface rocks peel off from the slope and roll down. Large rocks that leave the slope are called collapses. Debris and spalling are piled up in the cutting ditches, which affects the drainage of the ditches. If the drainage of cutting section is not smooth, it will cause diseases of other subgrade and pavement.

4. Subgrade damage caused by unfavorable geological and hydrological conditions.

When the highway passes through bad geological sections (such as debris flow, frozen soil, saline soil and karst caves) and major natural disasters (such as rainstorm), it may cause large-scale damage to the subgrade.

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