How to make a simple distinction between the types of soil at the construction site

Soil, gravel, hard soil, soft stone, sub-hard stone, solid stone, extra-hard stone. Classified according to the softness of the soil.

1. A type of soil refers to sand, humus, etc.;

2. The second type of soil refers to loess, soft saline soil and alkaline soil, loose and soft gravel, sand mixed with gravel and humus. The firmness coefficient of the first and second types of soil is low (0,5--0 8), and it can be excavated with a shovel and a few pickaxes.

3. Three types of soil refer to clay or ice clay, heavy loam, coarse gravel, dry loess or natural moisture loess mixed with gravel, etc., the firmness coefficient of the soil is 0 81--1 0, and it must be excavated with a shovel and a pickaxe. The four types of soil refer to the heavy loam soil with hard clay and gravel, the moraine clay containing boulder, mud slate, etc., with a firmness coefficient of 1 0 1 5, and the excavation of the soil must be carried out simultaneously with a shovel, pickaxe and crowbar.

Constitute. The substances in the soil can be summarized into three parts: the solid part, the liquid part, and the gas part.

Soil minerals are mineral particles of different sizes (sand, soil and gum) formed by the weathering of rocks. There are many types of soil minerals, and the chemical composition is complex, which directly affects the physical and chemical properties of the soil, and is one of the important nutrients of crops.

Solid soil particles composed of minerals and humus are the main body of the soil, accounting for about 50% of the soil volume, and the pores between the solid particles are occupied by gas and water.

The vast majority of soil gas is oxygen and nitrogen entering the atmosphere, and a small part is carbon dioxide and water vapor produced by life activities in the soil. The moisture in the soil enters the soil mainly from the surface and includes many dissolved substances.

There are also various animals, plants, and microorganisms in the soil.

By observing the thickness of the particles, the state when dry, the state when wet, and the degree of adhesion

More than half of the eggs (crushed) stones have a particle size of more than 20 mm, and the particles are completely dispersed, with no change in the surface and no sense of adhesion. More than half of the particles with a particle size of more than 2 mm (the size of a small sorghum grain) are completely dispersed, with no change in the surface and no stickiness.

Gravel sand has a particle size of more than 1 4 mm (the size of a small sorghum grain, the particles are completely dispersed, the surface does not change, and there is no sense of adhesion.

More than half of the coarse sand has a particle size of more than 5 mm (the size of fine millet) and the particles are completely dispersed, but there are individual cemented together. There is no change in the surface and no stickiness.

More than half of the medium sand has a particle size of more than millimeters, the particles are completely dispersed, partially cemented but scattered when touched, and there are occasional watermarks on the surface, and there is no sense of adhesion.

Most of the sand particles, coarse bean rice flour approximate (> mm), most of the particles are scattered, a small amount of glue, there are occasional watermarks (slurry) on the surface, and occasionally a slight sticky feeling. Most of the sand particles are similar to millet grains, the particles are scattered in a small amount, and most of the glue surface has a significant slurry turning phenomenon and a slight sense of adhesion.

What soil quality to use to design, different levels of road requirements are also different, if it is a block road is a requirement, if the residential front road is a requirement, factory roads and highways are not the same, the soil shown in the diagram can only be used for low-grade roadbed, it seems that there is no sand and gravel inside, there is more soil, and the compressive strength is definitely not up to the requirements.

According to the classification method of the "Code for the Design of Building Foundations", the rock and soil as the foundation of the building can be divided into rock, gravel soil, sand, silt, cohesive soil and artificial fill.

From the classification of rock and soil, there are different aspects and standards, the main classification is the classification of genesis, as well as according to the degree of hardness, according to the degree of integrity, according to the degree of weathering, according to the type of rock mass structure, according to the quality index of the rock mass, and according to the basic quality level of the rock mass to classify.

From the point of view of the classification of excavated rock and soil, the main category is a kind of soil can also be said to be soft soil, this kind of soil is also called sand, silt, alluvial sand layer, the degree of looseness can reach planting soil, silt or peat, the firmness coefficient can reach about it, the average bulk density is between, and the method of excavation can be excavated with shovels, hoes, etc.

For the second type of soil is also called ordinary soil, this kind of soil is silty clay, can also be moist loess, sand, sand, silt mixed with gravel or pebble planting soil or fill, the firmness coefficient is between, the average bulk density is between, the method of excavation can be excavated with a shovel and hoe, and less use a pickaxe to loosen the treatment.

Three types of soil is hard soil, this kind of soil is soft and medium dense clay, heavy silty clay, gravel soil, dry loess, loess containing gravel pebbles, silty clay, compacted fill, the solidity coefficient is between, the average bulk density is between, the method of excavation is mainly with a pickaxe, rarely with a shovel, hoe and other ways to excavate, for part of the use of crowbar to excavate.

The above content reference: Encyclopedia - Geotechnical.

Encyclopedia - Code for design of building foundations

From the construction point of view, it can be classified according to the hardness of the soil.

The engineering geological classification of soil refers to the division of soil and rock into eight categories according to the hardness of soil and rock and the difficulty of construction and excavation in building construction, which are soft soil, ordinary soil, hard soil, gravel and hard soil, soft stone, sub-hard stone, solid stone, and extra-hard stone.

Basic features: 1. Soil, like rock, is a product of natural history. The nature of soil is determined by its geological origin, formation time, place, environment, and mode, as well as the conditions of metagenetic evolution and current production. Such as the formation of loess in arid areas, moist and hot.

The laterite formed in the area and the silt formed in the still water area are completely different in nature.

2. Soil is a system composed of solid, liquid and gas phases. The solid phase is the main component of soil and is called the skeleton of soil. The pores between the soil particles can be filled with liquids or gases.

In the engineering classification of rock and soil, according to the classification method of the Code for Design of Building Foundation, the rock and soil as a building foundation can be divided into rock, gravel soil, sand, silt, cohesive soil and artificial fill.

According to the difficulty of earthwork excavation, the soil and rock are divided into eight categories, of which 1-4 types can be excavated by machinery and manually.

A type of soil: soft soil, mainly including sandy soil, silt, planting soil, silt, etc., solid coefficient.

Class II soil: ordinary soil, mainly including silty clay, moist loess, planting soil, fill, etc., with a solid coefficient.

Three types of soil: hard soil, mainly including compacted fill, gravel soil, dry loess, etc., solid coefficient.

Four types of soil: gravel and hard soil mainly include hard and dense cohesive soil or loess, medium compact clay soil or loess containing gravel pebbles, etc., with a solidity coefficient.

Five types of soil: soft stone Solidity coefficient Excavate with pickaxes and crowbars, and partially blast.

Six types of soil: sub-hard stone, solid coefficient, excavated with blasting, part of the wind pick.

Seven types of soil: solid stone with a solid coefficient of 10-18 excavated by blasting.

Eight types of soil: extra-strong stone with a solid coefficient of 18-25 excavated by blasting.

According to the "Engineering Classification Standard for Soil", soil is divided into macro-grained soil, coarse-grained soil, and fine-grained soil according to the relative content of different particle groups, which is the basic classification of soil.

According to the Code for Geotechnical Investigation, soil is divided into residual soil, slope soil, flood soil, impact soil, siltation soil, ice soil, aeolian soil, etc.

According to the particle size and plasticity index, soil is divided into gravel soil, silt soil, sandy soil, and cohesive soil.

Degree of hardness.

1. A type of soil (loose soil).

2. Class II soil (ordinary soil).

3. Three types of soil (hard soil).

4. Four types of soil (gravel and hard soil).

5. Five types of soil (soft soil).

6. Six types of soil (sub-hard stone).

7. Seven types of soil (hard stone).

8. Eight types of soil (extra hard stone).

In the method selection of foundation earthwork, according to the five engineering properties of rock and soil, they are classified, namely:

1. Internal friction angle.

2. Soil shear strength.

3. The natural moisture content of soil.

4. The dry density of the soil.

5. Looseness of soil.

According to the composition of the soil, it can be divided into cohesive soil, silt, gravel, silt soil, etc. According to the state of the soil, it can be divided into undisturbed soil, disturbed soil, and humus soil.

There are many types of soil, and its classification methods are very fast. In engineering, soil is divided into eight categories according to the difficulty of excavation, of which 1-4 types of soil are soil, and 5-8 types of soil are rocks. The engineering classification of soil listed in the table is an intuitive identification method, which is classified according to the difficulty of excavation and the different tools and methods used in excavation.

The difficulty of soil excavation directly affects the construction plan of earthwork, and the amount of labor consumes mu imitation and engineering costs. The harder the soil, the more labor is consumed, and the higher the project cost.

1. What classification criteria are used for earthworks?

1) Classification and characteristics of earthworks.

According to the different construction contents and methods of earthworks, earthworks have the following types:

1. Site leveling: refers to the earthwork project carried out by transforming the natural ground into the plane required by the design. This kind of earthwork construction area is large, the amount of earthwork is large, and mechanized operation should be adopted.

Foundation pit (groove) excavation: refers to the excavation width within 3m, the length to width ratio of 3 foundation pit or length ratio.

Foundation pit (groove) backfill: the foundation groove and the center of the house need to be backfilled after the foundation is completed, and in order to ensure the strength and stability of the fill, the fill soil and filling method must be correctly selected. The filling should be carried out in layers, and the same kind of soil should be used as far as possible.

The fill must have a certain compacting density to avoid uneven settlement of the building.

2) Earthwork construction characteristics.

Earthwork is one of the main projects of construction engineering, and its construction characteristics have the following characteristics:

1. The amount of earthwork is large and the labor intensity is high. For example, the site of a large-scale project is leveled, and the earthwork volume can reach more than millions of cubic meters, covering an area of dozens of square kilometers, and the construction period is long. Therefore, in order to reduce the heavy labor intensity, improve labor productivity, shorten the construction period, and reduce the project cost, when organizing the construction of earthworks, mechanization or comprehensive mechanization methods should be used as much as possible to carry out construction.

2. The construction conditions are complex. Earthwork construction is generally an open-air operation, and the soil is a natural substance with a wide variety. During the construction, it is greatly affected by the factors such as subtergeology, geology, underground obstruction, climate, etc., and there are many uncertain factors, therefore, it is necessary to make various preparations before construction, conduct sufficient investigation and research, study various technical data in detail, and formulate a reasonable construction plan for construction.

3. Subject to site restrictions. Any building needs a certain depth of embedding, the excavation of earthwork and the retention and storage of earthwork are limited by the construction site, especially in the construction of the city, the site is narrow, and there are many buildings around, often due to the improper construction plan, resulting in the unsafe and unstable construction facilities around the periphery. Therefore, before construction, it is necessary to have a detailed understanding of the structural form of the surrounding buildings and the distribution of various pipelines, be familiar with the geological and technical data, formulate a feasible construction safety plan, and make full use of the construction site.