Whether tectonic stresses have an effect on the fluid in the rock while the rock is deformed

Tectonic stresses cause rocks to crack or even fracture while deforming them. There are two types of faults: deep and large faults and general fractures. They each provide a passage for the circulation of various fluids and a place of storage in the earth's crust.

1. Deep and large fault zones.

It is caused by tectonic tensile stress, which reaches deep into the upper mantle, and the superheated rocks of the mantle (which are plastic and move slowly) melt and upwell due to the decrease in pressure, and the pressure is further reduced in the upwelling process, which promotes the separation of volatile components - gas-water hydrothermal fluids from the magma and forms fracture test eruptions, such as the mid-ocean ridge and the Great Rift Valley.

Second, the general fracture.

It occurs in an anticline structure where the compressive stress uplifts the massif, making it a magmatic intrusion, a large mine, and a structure for oil and gas deposits.

Among them, magma intrusion and vein formation are inextricably linked. During the rise of magma, the pressure and temperature decreased, and the volatile components increased relatively much, and when most of the silicate minerals have condensed into rocks, almost all the remaining materials are volatile. They exist in the form of hot gases and hydrothermal fluids, making them important mineral-forming media.

The gas-aqueous solution undergoes a chemical reaction and material exchange with the surrounding rock to form a contact metasomatic deposit. The other is because of the change of physical and chemical conditions, the gas-water solution filled in the fracture precipitates, and the filling deposit is formed.

It is a mistake that the structure of the rock does not have a significant effect on the engineering properties of the rock. Rock structure refers to the degree of crystallization of the materials that make up rocks, the size of mineral particles, the shape of minerals, and the interrelationships between them.

In magmatic rocks, the structure can be quietly divided into three categories: holocrystalline structure, semi-crystalline structure and vitreous structure according to the degree of crystallization of the rock. According to the absolute size of the mineral particles in the rock, the structure of coarse, medium, fine, and fine particles can be distinguished. According to the relative size of mineral particles, it can be divided into equal particle structure, unequal particle structure and patchy and patchy structure. According to the degree of self-shape of the minerals in the rock, it can also be divided into automorphic structure, semi-automorphic structure and other morphological structure.

Cementation refers to the material in the clastic rock that binds the crushed particles. It has two meanings: clay matter between detrital particles and chemical precipitate; Chemical precipitates filled in intergranular pores, excluding clays and other fine-grained substances.

The most common cements are silicon oxide (opal, chalcedony, quartz), carbonate (calcite, dolomite, etc.) and various oxides. Less common ones are barite, gypsum, anhydrite and pyrite.

Cementation is a self-generated mineral formed by sedimentary rock strata precipitated from pore solutions during the process of sedimentation and burial, and the function is to consolidate the loose sediments. It also has a great influence on the formation of the mechanical properties of rocks.

In a sense, it is more important than the composition of the rocks. The cementation types of sedimentary rocks are mainly divided into four types: basement cementation, pore cementation, contact cementation and mosaic cementation. The strength of the rock block is the highest in the basement cementation, followed by the pore cementation, and the lowest in the contact cementation.

The higher the degree of cementation, the tighter the connection between the minerals and rock particles, and the denser the rock, the higher the rock strength.

RocksIt is false to say that the structure of the structure has no significant effect on the engineering properties of the rock.

The factors affecting the properties of rock engineering can be summarized into two aspects:

The first is the internal cause, that is, the internal conditions of the rock itself, such as the mineral composition, structure, and structure of the rock;

The second is external factors, that is, objective factors from the outside of the rock, such as climatic environment, weathering, hydrological properties, etc. Therefore, the mineral composition, structure, and structure of rocks, as well as the weathering of rocks, the action of water, etc., all directly affect the engineering properties of rocks.

The mineral composition of the rock has a direct impact on the engineering properties of the rock. Compared with the complex rock, the former is more resistant to weathering than the latter. For example, quartzite (monomineral) is the main mineral of quartz, which has an average compressive strength of 250 MPa, while granite (double mineral) contains not only quartz, but also flake mica and feldspar with medium cleavage, with an average compressive strength of 200 MPa, which shows that the strength of granite is lower than that of quartzite.

The hardness of the mineral is closely related to the compressive strength of the rock. Such as quartzite and marble, because the quartz in quartzite is much harder than the calcite in marble, the compressive strength of quartzite is 150 300 MPa, and the compressive strength of marble is 100 250 MPa.

The density of the mineral determines the density of the rock, and the density of the rock with more iron and magnesia minerals is greater than that of the rock with more silicon-aluminum minerals. For example, the main mineral components of gabbro are pyroxene and mafic plagioclase, while the main mineral components of granite are feldspar and quartz, so the average density of gabbro is much greater than that of granite.

How many forms of failure can a rock have under different stress states?

Answer: When the specimen is damaged by uniaxial compressive load, three failure forms can be produced in the specimen:

In the shear failure of the X-shaped conjugate inclined plane, the shear stress on the failure surface exceeds its shear strength, resulting in rock failure. In the shear failure of a single inclined plane, the shear stress on the failure surface exceeds its shear strength, resulting in rock failure. In tensile failure, the tensile stress on the failure surface exceeds the tensile strength of the surface, resulting in tensile failure of the rock.

Elastic deformation, plastic deformation and viscous deformation can occur when the rock is loaded. In general, rocks have viscoelastic properties (hysteresis), that is, the generation and recovery of strains lag behind the change of stress.

Answer: A, C, E

The physical and mechanical collapse properties of the structural plane that have a great influence on the rock liquid circle are mainly the occurrence, continuity and shear strength of the structural plane.

The main characteristics of the structural plane are as follows:

Scale: The size of the structural plane varies greatly. The largest one can stretch for tens of kilometers and the width can reach tens of meters.

Orientation: that is, the occurrence of the structural plane. Spacing:

Refers to the vertical distance between adjacent structural faces, usually the average spacing of a set of structural surfaces. It is an important indicator of the integrity of the rock mass and the size of the rock mass.

The methods that affect the mechanical properties of rock mass are as follows: chain delay

Confining pressure, the confining pressure increases, increases the strength of the rock, increases the toughness of the rock. temperature, the temperature increases, reducing the strength of the rock; Increases the toughness of rocks. Pore fluid pressure, pore fluid pressure increases, reduces the strength of the rock, increases the brittleness of the rock.

Strain rate, strain rate decreases, the strength of the rock decreases, the toughness increases, and ductile deformation is easy to occur.

Rocks are solid aggregates with a stable shape composed of one or several liquid-responsive minerals and natural glass. Rocks composed of one mineral are called monooretic rocks, and at the same time, marble is composed of calcite, quartzite is composed of quartz, etc.

Rocks composed of several minerals are called polyminerals, such as granite composed of minerals such as quartz, feldspar and mica, gabbro composed of mafic plagioclase and pyroxene, and so on. Liquids such as oil, gases such as natural gas, and loose sand and mud that do not have a certain shape are not rocks.

Differences: The engineering properties of rock are mainly related to the mineral composition, structure and structure and degree of weathering, etc., and the engineering properties of rock mass are not only determined by the physical and mechanical properties of rock, but also mainly related to the direction and distribution of square slag cut by cracks and other fractures inside the rock mass, the density of the cutting, the weakness of the broken beams and broken belts, etc.

Influencing Strength Factors: a. Mineral Composition; b-band band structure; c. Structure; dWeathering.

Deformation property factors: a. the type of structural surface; b structure.

Answer]: According to the change of the shape and pure state of matter of the whole process curve of stress and strain, it can be divided into five stages. (1) Compacting stage.

It is characterized by an upward concave shape of the stress-strain curve, that is, the strain decreases with the increase of stress. (2) Elasticity stage. At this stage, the stress-strain curve is basically straight, and in the elastic stage, the rock will produce some irreversible deformation due to the continuous crack propagation after loading.

Because pants can only be an approximate elastic medium. (3) Plasticity stage. When the stress value exceeds the yield stress, the curve is concave as the stress increases, and the strain increases (softens) obviously, and the plastic stage is entered.

4) Strain softening stage. Although the peak stresses have been exceeded at this point, the rock still has some bearing capacity. (5) Friction phase.

It only shows the ability of the rock to resist external forces due to the friction of the fracture surface after the macroscopic fracture surface is generated.