With the rapid development of social economy, high-grade highway construction has penetrated all over the country. However, due to the improvement of road grade, more and more roads are built in difficult terrain sections. Sometimes the slope problem restricts the progress, quality and investment control of our road construction, and also affects the road maintenance and environmental protection in the future. From the news, we can also see that after several consecutive rainstorms, some slopes have been seriously landslided, collapsed and washed out, which has a great impact. Therefore, the importance of road slope has been one of the important technical issues on the agenda.

1, classification of road slope diseases

1. 1 Landslide is that the soil or rock mass on the subgrade hillside gradually loses its supporting force due to the long-term influence of groundwater and surface water activities, and the whole body slides down a weak surface under the action of its own weight. Landslides can be divided into traction landslides and nappe landslides according to their mechanical characteristics. Traction landslide is that the lower part slides first, so that the upper part loses support and deforms and slides. Generally, the speed is slow, the transverse tensile cracks are developed, and the surface is mostly stepped or steep.

1.2 Collapse The so-called collapse means that the whole rock and soil mass breaks away from the parent body, suddenly collapses from the steep slope, violently flips and jumps along the slope, and finally accumulates at the foot of the mountain. It is sudden and harmful.

1.3 spalling refers to the weathering of the slope surface and continuous rolling down the slope under the action of scouring and gravity.

2. Slope stability evaluation

2. 1 Slope stability evaluation basis

Before slope stability evaluation, it is necessary to collect engineering geological environment data, which is not only the basis for selecting slope stability evaluation methods, but also the basic data for slope stability evaluation.

2.2 Slope stability analysis

Slope stability has always been an important research content in slope engineering. Slope stability analysis mainly adopts qualitative and quantitative evaluation methods. According to the evaluation results of the two methods, a unified conclusion is drawn and the slope treatment measures are determined.

2.2. 1 qualitative analysis of stability

The qualitative analysis of slope stability can comprehensively consider various factors affecting slope stability, and can quickly evaluate the stability and development trend of slope.

A. Slope treatment analysis in road route design

At present, there are many "loess high slopes" on the landscape along the highway, and landslides and collapses often occur. This has a lot to do with whether the design of road plane and longitudinal plane is suitable. First of all, mountain roads should meet the minimum technical standards. It is suitable for bending, and it is suitable for sloping. It is not possible to unilaterally pursue a straight line and reduce large-scale filling and excavation. The second is to make full use of the terrain. In the past, the low-grade road was "local barbecue", and the high-grade road was not easy to walk. However, the number of damaged mountains should be minimized. The third is to make full and proper use of the role of artificial structures.

B. Analysis of envelope problems

With the development of science and technology, people have developed from traditional passive support to consider strengthening the rock and soil itself, improving its mechanical properties and enhancing its integrity, so as to achieve the purpose of stabilizing the slope. The mature technologies in this field include: grouting or high-pressure jet grouting to strengthen rock and soil, reinforced soil, bolt-shotcrete support, prestressed anchor cable and so on. This technology can be said to be the main direction of slope stability protection technology.

C. Comparative analysis of topographic and geological conditions

Slope instability is produced under certain geological conditions, and its formation has certain unfavorable geological basis, micro-geomorphological characteristics and surface signs in its development stage. Therefore, we can compare and analyze the strata, lithology, geological structure, hydrogeological conditions, soft interlayer and soil properties of the slope to be judged with the surrounding stable slopes, stable slopes and unstable slopes under similar geological conditions and slopes at different sliding stages, and analyze and judge the stability of the slope in combination with possible changes in geological conditions.

2.2.2 Quantitative analysis of stability

The quantitative analysis and evaluation of slope stability is based on qualitative analysis and evaluation. According to the geological profile of the slope determined by investigation, the stability coefficient of the slope to be evaluated is calculated by using the static balance theory, and the stability of the slope is evaluated according to the calculated stability coefficient. At present, the commonly used quantitative analysis and evaluation method in engineering is mainly transfer coefficient method.

3, prevention and control measures

3. 1 Prevention and treatment of landslide caused by common subgrade diseases.

3. 1. 1 control principle

Prevention: In areas where new landslides may occur, necessary engineering measures should be taken to prevent the occurrence of new landslides or the revival of ancient landslides.

B there is a process to prevent the occurrence and development of early landslides, and early rectification can get twice the result with half the effort.

C combination of one-time radical treatment and phased remediation Landslides should generally be thoroughly cured at one time, leaving no future trouble. However, for landslides with large scale, complex nature and slow deformation, which will not cause major disasters for a while, they can also be rectified by stages under the overall planning. At the same time, pay attention to the effect of each stage of the project, and provide the basis for determining the next stage of the project.

3. 1.2 prevention and control measures should be based on the understanding of the causes of landslides, prioritize various factors that induce landslides, and take corresponding engineering measures. Common prevention measures include drainage, weight reduction, retaining soil, improving physical and mechanical properties of soil, etc.

A drainage measures the occurrence and development of landslides are related to the role of water, and drainage is the basis for preventing and controlling all kinds of landslides. However, practical drainage methods should be adopted according to specific conditions.

B. Weight reduction measures When the sliding surface is not deep, and the sliding body is steep and gentle, and there is a stable hillside outside the landslide range, it is a simple and economical prevention measure to reduce the sliding force of the landslide. It is best to pile the thinned soil at the foot of the slope to increase the sliding resistance.

C retaining measures according to the size of the sliding body thrust, you can choose a suitable retaining structure to prevent sliding.

(1) Anti-sliding retaining wall. The construction is convenient and the effect of stabilizing landslide is quick. Anti-slide retaining walls are mostly gravity, stone, concrete or reinforced concrete.

(2) Anti-slide piles. Small disturbance to the sliding body, simple operation, short construction period, quick effect, small traffic disturbance, safety and reliability.

(3) Anchor retaining wall. Used for thin-layer massive landslides or landslides with shallow bedrock burial depth and steep horizontal sliding surface of sliding body.

(4) Anti-sliding opening. If the lower edge of the sliding surface is at a higher position on the slope, an open pit sliding hole can be set according to the foundation conditions, and the top of the hole is backfilled with earth and stone to support the sliding body, or the sliding body falls outside the line above the top of the hole. However, this measure has great interference to traffic, great construction difficulty and high cost, and it is only used when other measures are difficult to work.

D improve the physical and mechanical properties of landslide soil, and reinforce and stabilize the landslide by physical and chemical methods.

E. When the above rectification measures are ineffective, if the economy and technology are reasonable, we can consider changing the line.

3.2 Prevention and treatment of common subgrade diseases-collapse

Road slope collapse is a common disease, which often blocks traffic when it is serious. The obvious differences between collapse and landslide are: collapse occurs rapidly, the damaged body is scattered, and there are dumping and tumbling phenomena; Generally, landslides always slide slowly along a fixed sliding surface. Too deep excavation, too steep slope, or exposure of weak structural plane due to slope cutting will make the rock mass on the slope lose its support and collapse under the action of water scouring or earthquake. Measures to prevent and control collapse mainly include:

Dangerous stones above the subgrade should be inspected and removed in time, especially before the rainy season. If there is a road section that threatens traffic safety, it can be reinforced by embedded support according to the terrain and rock conditions.

B in small-scale collapse or rockfall areas, the method of total removal should be adopted as far as possible; If the bedrock is seriously damaged and the sources of rockfall materials are abundant, it is advisable to build rockfall platforms, rockfall troughs and other interception structures.

C for the high slope which is easy to collapse due to the existence of weak structural plane, measures such as retaining wall or buttress can be taken to support the slope according to the situation to prevent the weak structural plane from opening or expanding.

D for places where the toe of the slope is easy to collapse due to river erosion, the river bank should be protected.

E. In the area where collapse may occur, ground drainage facilities must be made.

In highway construction, it is necessary to choose a reasonable method to evaluate its slope stability, and determine reasonable slope treatment measures according to the evaluation results to ensure the safety of highway operation and save investment.

For more information about project/service/procurement bidding, and to improve the winning rate, please click on the bottom of official website Customer Service for free consultation:/#/? source=bdzd