CN110470522B - A method for prefabricating rock mass samples of fracture network with different water saturation - Google Patents

Abstract

The invention discloses a method for prefabricating fracture network rock mass samples with different water saturation, belonging to the field of experimental research and application of water-bearing fracture rock mass in geotechnical engineering. The invention utilizes the prepared grouting mold, and according to the spatial form and water saturation of different rock mass fissures, introduces different contents of gas before water condenses into ice, and makes ice of various shapes with different cavities in it. Place the ice mold at the space set by the grouting mold at intervals and pour the mixed slurry material. After pressure molding, high temperature curing is performed; In this way, the preparation of rock mass samples with different water saturation fracture network can be realized. The invention can complete the production of non-penetrating and different water saturation fractured rock mass samples, is beneficial to various experimental researches on fractured rock mass with different water saturation, and promotes the development and application of fractured rock mass mechanics.

Description

A method for prefabricating rock mass samples of fracture network with different water saturation

technical field

The invention relates to the field of grouting of fractured rock mass, water seepage of water-containing fractured rock mass, strength test of water-containing fractured rock mass, etc., realizing the production of rock mass samples of water saturation fracture network, and satisfying the mechanical properties of fractured rock mass under different conditions. Testing and testing requirements, in particular, a method for prefabricating rock mass samples with different water saturation fracture networks.

Background technique

Mining engineering, tunnel engineering, water conservancy engineering and other geological engineering involving water blocking and reinforcement of rock mass, due to the existence of cracks in the rock mass, the mechanical properties of the original rock mass are changed, and the cracks in the rock mass often contain different water saturation. moisture. In view of the importance of fractured rock mass in major engineering construction, it is necessary to carry out mechanical experiments on fractured rock mass with different water saturation, but due to the influence of experimental methods and existing technologies, it is often impossible to collect samples from the original rock. Laboratory-scale experiments on fractured rock mass are required using rock mass samples.

For the structure of rock mass samples containing natural fractures, people often complete the construction of single fracture rock mass by adding paper sheets, 3D printing rock mass molds, etc. For example, "A Preparation Method for Non-penetrating Fractured Rock Mass Samples Based on 3D Printing Technology" (ZL201511019619.8) discloses a simple mold made by 3D printing technology to realize the preparation of non-penetrating fractured rock mass samples, but using The mold can only realize the printing and construction of single or several discontinuous fractures, and this method is suitable for non-penetrating fractured rock mass, and cannot realize the composition of complex fracture network, and the prefabricated structure formed by printing and forming sample fractures is not pulled out The performance of the fractured rock mass has a great influence, and the water content in the fracture cannot be considered; "An Indoor Single-fractured Rock Sample Preparation Device" (ZL201410052815.4) discloses a single-fractured rock mass preparation method, but The situation of the fracture network cannot be considered, let alone the water content in the fractures, and the reaction of fractures with different saturation cannot be realized; and the natural fractures are often water-bearing, and the water has a great influence on the performance of the fractured rock mass, so it cannot be considered. water content in the fissures.

There is currently no effective fabrication method to add and construct the same fissure network as the geological rock mass in the specimen, especially a simple experimental fabrication method for the fissure network rock mass containing different water saturation in the fissures.

SUMMARY OF THE INVENTION

In view of the current problems in the preparation of fractured rock samples with different water saturation and fracture network, a method of prefabricating fractured rock samples with different water saturation is proposed for the preparation method of natural fracture samples. The purpose is to provide a method for producing fractured rock mass samples with different water content, different fracture shapes, and staggered fracture networks, so as to provide strong technical support and test basis for fractured rock mass testing, and at the same time reduce the test cost. The test is simple, inexpensive and easy to operate.

To achieve the above object, the concrete technical scheme adopted by the present invention is as follows:

A method for prefabricating rock mass samples of fracture network with different water saturation, the method comprises the following steps:

The first step is to determine the rock mass fracture parameters

Measure the geometric length, width, shape, water saturation, fissure position, interlayer and staggered relationship of multiple fissures in the rock mass in the engineering site, so as to determine the test size parameters that conform to the actual engineering.

The second step is to prepare the ice mold

2.1) Use wood material to make a crack network water model that meets the test size parameters determined in the first step. The water model should be able to hold water and ensure that no large deformation occurs under freezing conditions;

2.2) Fix the various types of water molds made in step 2.1) in a freezing environment, and pour water into the water mold until it is full, and fill the water mold with different contents of air according to the water saturation of the cracks determined in the first step;

2.3) After the water in the water mold freezes and freezes until the ice cubes are formed, the water mold is removed to make an ice mold with different cavities inside, so as to realize the characterization of different water saturation.

The third step is to prepare the rock mass sample forming device and construct the rock mass sample

3.1) The rock mass sample forming device includes a compression beam 1, a hydraulic column 2, a connecting body 3, a cover 4 and a grouting mold 7; the compression beam 1 is fixed on the floor, and a hydraulic column 2 is installed in the middle; the grouting The mold 7 is placed directly under the hydraulic column 2, the cover 4 is installed on the top of the grouting mold 7, and the connecting body 3 is installed on the upper surface of the cover 4, so as to pressurize the top plate of the grouting mold 7;

3.2) According to the crack space structure and position determined in the first step, place the ice mold formed in the second step at the space position set by the grouting mold 7, and pour the prepared ice mold into the grouting mold 7 under low temperature conditions. The mud material is compared, and the pressure beam 1, the hydraulic column 2 and the connecting body 3 are used on the top of the grouting die 7 to slowly press the cover 4 of the grouting die 7 until the rock mass sample is stabilized;

3.3) After the rock mass sample is preliminarily processed and formed, the grouting mold 7 is removed, and the rock mass sample is placed in a high temperature environment for curing to ensure that the ice mold inside the rock mass sample melts into water and fills the internal cracks.

Further, in the step 2.2), the water mold is a detachable wooden component with different shapes and sizes of films laid on the inner surface, and the component is required to be able to be filled with water and can be completely disassembled; and the two ends of each group of water molds 8 or There are air holes 9 (which can be temporarily sealed) in the middle, and the water is poured into the water mold 8 until it is full and sealed. With the help of the air hole 9 at the end of the water mold 8 or the air hole 9 in the middle position, a certain amount of gas is input into the water mold 8, and the other end is The air hole 9 flows out an equal amount of water to ensure the accuracy of the water saturation, then its water saturation is the total charged water volume minus the drainage volume and then divided by the total charged water volume.

Further, in the step 3.2), other rock mass spaces around the fracture ice mold should be poured as soon as possible, the purpose of which is to prevent the ice mold from melting and destroying the geometry and distribution characteristics of the fracture network.

Further, the grouting die 7 is a cube steel plate assembly with a size of 300mm*300mm*300mm.

Further, the compression beam 1 is a steel "lip" plate beam with a height of 1000mm.

Beneficial effects of the present invention: The present invention provides an effective method for making rock mass samples, which can ensure that the shape, size and spatial position of the fracture network ice mold remain stable without changing. The invention realizes the production of water-bearing fractured rock mass, especially for the production of rock mass samples containing fractures with different degrees of water content, and is useful for further research on the mechanical properties of water-bearing fractured rock mass, the influence of water saturation, and various tests, such as fractures. Rock mass grouting, fractured rock mass permeability, fractured rock mass fracturing flow, etc. are of great significance.

Description of drawings

Fig. 1 is a working flow chart of a method for prefabricating rock mass samples of fracture network with different water saturation according to the present invention;

Fig. 2 is a device layout diagram of a method for prefabricating rock mass samples of fracture network with different water saturation according to the present invention;

3 is a schematic diagram of a water model of a method for prefabricating rock mass samples of fracture networks with different water saturations according to the present invention;

In the picture: 1. Compression beam; 2. Hydraulic column; 3. Connecting body; 4. Cover; 5. Ice mold; 6. Gas void; 7. Grouting mold;

Detailed ways

The specific embodiments of the present invention are described in detail below with reference to the technical solutions and the accompanying drawings.

As shown in Figure 1, a method for prefabricating rock mass samples with different water saturation fracture network is divided into three stages: ① Preparation stage, in this stage, the geometric parameters of the fractured rock mass to be studied including fractures need to be determined Various parameters such as fracture location, network staggering, and water saturation are determined, so as to construct a fractured rock mass sample model that is more in line with the actual engineering; ② Constructing ice model, this stage is mainly based on the determined rock mass fracture network parameters. Use wooden water molds to make ice molds with a specified air content to meet the water saturation requirements of rock mass fissures; ③ To construct fractured rock masses, in this stage, place the ice molds in the grouting mold according to the designed spatial position and irrigate them. The slurry with a good proportion is added, and after the pressurized slurry is stably formed, high temperature curing will form a water-containing (different water saturation) fractured rock mass.

As shown in FIG. 2 , a method for prefabricating rock mass samples with different water saturation fracture networks in the present invention is realized by a rock mass sample forming device, which includes a compression beam 1 , a hydraulic column 2 , a connecting body 3 , and a cover 4 and the grouting mold 7; the compression beam 1 is a steel "lip" plate beam with a height of 1000mm fixed on the floor, and a hydraulic column 2 is installed in the middle; the grouting mold 7 is a cube with a size of 300mm*300mm*300mm The steel plate assembly has a movable cover 4 installed on the top, and a connecting body 3 is installed on the upper surface of the cover 4; The pressure beam 1 exerts pressure on the casting mold 7 and the slurry in it.

As shown in Figure 3, according to the measured parameters, make water molds 8 and lay a film to seal, each group of water molds 8 are left with air holes 9 at both ends or in the middle, and water is poured into the water molds 8 to full and sealed, with the help of the water molds 8 The air hole 9 at one end or the middle position inputs a certain amount of gas into the interior, and the other end flows out an equal amount of water to ensure the certainty of water saturation, and then the entire water mold is moved to a freezing environment for freezing. After the water in the water mold freezes Remove the surrounding water mold 8 and the film; place the ice mold 5 containing the gas void 6 into the grouting mold 7, pour the proportioned slurry into the grouting mold, and use the compression beam 1, the hydraulic column 2, the connecting body 3. The cover 4 is press-molded and cured at high temperature after molding.

The specific operation of the method of the present invention is as follows:

The first step is to determine the rock mass fracture parameters

Measure the geometric length, width, shape, water saturation, interlayer and staggered relationship of multiple fissures in the rock mass in the engineering site, and determine the test size parameters;

The second step is to prepare the ice mold

(1) Use wood material to make a crack network water model 8 that meets various types of test size parameters, and the water model 8 is required to be able to hold water and ensure that no large deformation occurs under freezing conditions;

(2) fix and place various types of water molds 8 in a freezing environment, and pour water into the water mold 8 until it is full, and fill the water mold 8 with air of different contents according to the determined water saturation of the fissures;

(3) until the water in the water mold 8 freezes and freezes until the ice cubes are formed, the water mold 8 is removed, and the ice molds 5 of various shapes with different gas voids 6 are made into ice molds 5, thereby realizing the characterization of different water saturation;

The third step is to prepare the rock mass sample forming device and construct the rock mass sample

(1) According to the crack space structure and position determined in the first step, place the ice mold 5 at the space position set by the grouting mold 7, and pour the mixed slurry material under low temperature conditions to prevent the ice mold 5. Rapid melting; and relying on the compression beam 1 and the hydraulic column 2, using the connecting body 3 to slowly apply force to the cover 4 of the grouting mold 7 to form, until the rock mass sample is formed stably;

(2) After the rock mass sample is preliminarily processed and formed, the grouting mold 7 is removed, and the rock mass is placed in a high temperature environment for maintenance to ensure that the internal ice mold melts into water to fill the internal cracks.

The method and equipment provided by the invention are simple to manufacture, the method process is simple and easy to implement, the cost is low, and it is easy to implement in the laboratory. The invention can realize the production of any rock mass sample containing cracks, especially for the production of cracked rock mass that does not pass through the internal water saturation and crack network, which is beneficial to promote cracked rock mass mechanics, cracked rock mass seepage mechanics, cracks The development of rock mass freeze-thaw mechanics.

Claims (5)

1. A method for prefabricating fracture network rock mass samples with different water saturation degrees is characterized by comprising the following steps:

firstly, measuring rock mass fracture parameters

Measuring the geometric length, width, shape, water saturation, fracture position, multi-fracture interlamination and staggered relation of the fractures in the rock mass in the engineering site, thereby determining the test dimension parameters which accord with the actual engineering;

second, preparing the ice mold

2.1) manufacturing a fracture network water model according with the test size parameters determined in the first step by using a wood material, wherein the water model can contain water and can not generate large deformation under a freezing condition;

2.2) fixedly placing the water model manufactured in the step 2.1) in a freezing environment, filling water into the water model until the water model is full, and filling air with different contents into the water model according to the fracture water saturation determined in the first step;

2.3) freezing ice until ice blocks are formed after water cooling in the water mold, removing the water mold, and manufacturing an ice mold with gas gaps inside, thereby realizing characterization of different water saturation degrees;

thirdly, preparing a rock mass sample forming device and constructing the rock mass sample

3.1) the rock mass sample forming device comprises a pressurizing beam, a hydraulic column, a connecting body, a sealing cover and a grouting mould; the pressurizing beam is fixed on the floor, and the middle part of the pressurizing beam is provided with a hydraulic column; placing a grouting mould under a hydraulic column, installing a sealing cover at the top of the grouting mould, and installing a connector on the upper surface of the sealing cover to realize pressurization of slurry in the grouting mould;

3.2) according to the crack space structure and position determined in the first step, placing the ice mold manufactured and formed in the second step at the space position set by the grouting mold, pouring proportioned slurry materials into the grouting mold under the low-temperature condition, and slowly applying acting force to a sealing cover of the grouting mold at the top of the grouting mold by utilizing a pressurizing beam, a hydraulic column and a connecting body for forming until the rock mass sample is stably formed;

3.3) after the rock mass sample is initially processed and formed, the grouting mould is removed, the rock mass sample is placed in a high-temperature environment for maintenance, and the ice mould inside the rock mass sample is melted into water to fill the internal cracks.

2. The method for prefabricating fractured network rock mass samples with different water saturation degrees according to claim 1, wherein in the step 2.2), the water model is a detachable wood component internally provided with a thin film; and the two ends or the middle part of each group of water molds are provided with air holes, water is filled into the water molds to be full and sealed, air is input into the water molds by virtue of the air holes at the end parts or the middle parts of the water molds, and the same amount of water flows out of the air holes at the other ends so as to realize accurate representation of water saturation.

3. A method of prefabricating fracture network rock mass samples of different water saturation according to claim 1 or 2, wherein the grouting pattern is a square steel plate assembly with dimensions 300mm x 300 mm.

4. A method of prefabricating fractured network rock mass samples of different water saturation levels according to claim 1 or 2, wherein the compression beams are steel "die" plate beams with a height of 1000 mm.

5. A method of prefabricating fractured network rock mass samples of different water saturation levels as claimed in claim 3, wherein the compression beam is a steel "die" slab beam with a height of 1000 mm.

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