How to determine the sliding surface of the soil slope, the shape of the sliding surface of the cohe

In soil mechanics, the strip method is generally adopted, and the various specifications are slightly different. In general, the land system uses the unbalanced thrust method (transfer coefficient method) to solve the sliding surface.

The methods for determining the sliding surface of soil slope include methodical method and unbalanced thrust method.

1. The division is as follows:

Assumptions: 1) The tangential force ti on the sliding surface is equal to the shear strength fi exerted by the soil on the sliding surface;

2) The position of the application point of the normal force e on both sides of the soil strip is known, and it acts on the bottom surface of the soil strip 1 3 height.

The analysis shows that the position of the interstrip force action point has little effect on the stability safety factor of the soil slope. The Yangbu strip division method can satisfy all stress conditions, but the assumption of the thrust line must meet the rationality requirements of the interstrip force.

2. Unbalanced thrust method:

Two solutions are provided: explicit and implicit. Depending on the specification, different solutions are required.

Friends who are familiar with the unbalanced thrust method should know very well that the explicit solution uses the safety factor to increase the sliding force, while the implicit solution reduces the strength parameters of the rock and soil mass. The implicit solution should be used to meet the general definition of the factor of safety, and in other polyline sliding analysis methods, the factor of safety is also used to reduce the strength parameters of rock and soil. Of course, if the specification requires that an explicit solution be used, then the result of the explicit solution can be used, and the result of the explicit solution will usually be larger than the implicit solution.

The explicit solution method came about because in the era when there were no computers, explicit solutions were more suitable for hand calculations.

The relationship between the shape of the sliding surface and the soil quality of the slope is as follows

1. Homogeneous clay soil, the shape of the sliding surface is cylindrical in space, curved on the profile, close to vertical at the top of the slope, and tends to be horizontal at the foot of the slope;

2. Homogeneous and non-cohesive soil, the sliding surface is an inclined plane in space, and the profile is close to an oblique straight line;

3. When there is a soft layer at the bottom of the soil slope, there may be a composite sliding surface with a combination of curves and straight lines.

The difference between rock slope and soil slope in a slope

1. The difference between the two includes three aspects: material composition, failure mechanism, and stability calculation method. The material composition of the slope is the difference between soil and rock. Soil and rock are similar in material composition (soil is a weathering product of blind rocks), but the structure is very different.

Soil is a loose accumulation of particles, while rock mass is a block with various irregular joints and faults.

2. There is a difference in the failure mechanism between the two. The failure of soil slope is mainly the problem of soil stability, which is generally a sliding failure, which is caused by the shear stress on the sliding surface exceeding its shear strength. The instability and failure of rock slope often have a great relationship between the sliding surface and the joint development of rock mass.

In addition to sliding failure, there is also collapse failure, which has no obvious failure surface and is caused by the stress exceeding the strength of the rock mass.

3. In the analysis and calculation, both are calculated based on sliding failure, and the methods used are also different. The soil slope is generally based on the Swedish arc strip method, and the soil slope rock slope is generally based on the transfer coefficient method due to the existence of multiple groups of structural planes.

The shape of the sliding surface of the cohesive soil slope is generally approximately arc surface.

The sliding surfaces of soil slope sliding are: arc, plane, and composite sliding surface.

Circular sliding usually occurs in more homogeneous cohesive soil slopes; Plane slip usually occurs in cohesive soil slopes; The composite sliding surface occurs in a very uneven soil slope. In the absence of seepage, the calculation methods for the stability safety factor of cohesive soil slope are: 0 analysis method, Swedish strip division method, and simplified Bishaw method.

In general, there are three situations:

The first is homogeneous clayey soil, the shape of the sliding surface is cylindrical in space, and the profile is curved (arc), close to vertical at the top of the slope, and tends to be horizontal at the foot of the slope. the second is homogeneous and cohesive soil, the sliding surface is a slope in space, and the grinding and trapping profile is close to an oblique straight line; Third, when there is a soft layer at the bottom of the soil slope, a curve may appear.

Explanation of the circular sliding method:

The sliding soil with circular arc shape is divided into several strips and calculated separately, and the sum is taken, and the ratio of the total anti-sliding moment of the sliding soil to the center of the circle is taken as the safety factor. Applied disciplines: water conservancy technology, hydraulic construction, water retaining buildings.

This method simply regards the sliding surface as an arc, and considers that the sliding soil is rigid, and does not consider the thrust between the slits, or only considers the horizontal thrust between the slits (Bishop formula), so the calculation results can not be completely in line with reality, but because the calculation concept is clear, and the stability of the soil slope under complex conditions can be analyzed, it is widely used in the practice of various countries. Either way. The role of seepage must be considered.

When the soil slope of non-cohesive soil material slides, the shape of the sliding surface is generally a polyline.

The sliding surface of the soil slope is mainly sliding surface and branch sliding surface. The sliding surface is usually steep up and gentle at the bottom, almost arc-shaped. Sometimes there is only one, sometimes there can be several, so it can be divided into the main sliding surface and the branch sliding surface.

Polished surfaces and scratches can be clearly seen on the sliding surface. Sometimes there are obvious disturbances and drag folds on the sliding surface, which constitute the sliding belt. The immovable body (parent) below the sliding surface is called the landslide bed.

Some landslides do not have obvious sliding surfaces, and there is a soft plastic sliding zone on top of the landslide bed.

The sliding surfaces of soil slope sliding are: arc, plane, and composite sliding surface.

Summary. <>

<> main difference between sandy soil slope sliding and cohesive soil slope sliding.

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The main difference between sandy soil slope sliding and cohesive soil slope sliding.

The main difference between the sliding morphology of sandy soil slope and cohesive soil slope.

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Sandy soil has no cohesiveness, the particles are independent between the touching grains, there is no tensile force, so it is easy to flow, and the friction between the particles is not enough to bear a high weight, so it is difficult to accumulate. The cohesive soil is the opposite, so the viscous Shenyun orange soil has a gentle slope, and the sandy tour soil has a steep slope.