CN104280281B - A Method for Repairing Defective Rock Samples in Rock Tests - Google Patents

Abstract

A method for repairing defective rock samples in rock tests, selecting incomplete rock samples and rock samples with insufficient size that can no longer be subjected to shear tests and split tests, and cleaning and removing ash from the rock samples; preparing K39 crystal resin , within 35°C-45°C (in a warm water bath), prepared according to the following weight ratio: defoamer 0.2%-0.8%, accelerator 0.3%-0.5%, hardener 0.6%-1%, weighed according to needs After the resin is prepared, add in order according to the weight ratio: accelerator, hardener, and defoamer, and add it at intervals of about 20 seconds, and must be stirred evenly; first pour the stirred resin into a mold that has been cleaned and coated with lubricating oil , until the surface of the mold is covered with resin, put the rock sample of the defect described in step 1 into the mold, and finally add resin to the predetermined size, and wait for it to solidify; take the mold 1 to 2 hours after the resin solidifies, The surface of the demoulded rock sample is then polished. The invention reduces the batch collection and drilling of rock samples, and improves the utilization rate of drilling samples and incomplete and irregular rock samples in the construction process.

Description

A Method for Repairing Defective Rock Samples in Rock Tests

technical field

The invention discloses a defect rock sample repairing method in rock test, which is used for reforming the defect problem of sample selection before rock splitting and shearing test.

Background technique

The strength parameter of rock is one of the important parameters in rock engineering design. Tensile failure is one of the basic forms of rock failure, and tensile strength is an important index of rock mechanical properties, which is of great significance to underground engineering design, analysis and calculation. Due to the complicated processing of rock specimens by the direct tension method, the test operation is difficult. Therefore, the indirect tensile test-split method is widely used to measure the tensile strength of rock. At present, the most commonly used rock strength theory or rock failure criterion in engineering is still the Coulomb criterion, Mohr criterion and Griffith criterion, and one of the most commonly used rock strength parameters is the rock internal friction angle and cohesion C. These parameters can be determined by rock triaxial test and shear test.

However, in the process of test and measurement, there will be insufficient rock samples, defects and insufficient sizes of rock samples in operation, and discrete problems of test results caused by rock masses in different sections and rock masses in geological environments. Therefore, it is necessary to make up and improve the rock samples in the above common problems.

Previous studies mainly used mortar, gypsum, etc. to fill, and water was involved in infiltration during the implementation process, so that the mortar, etc. entered the interior of the rock mass with the infiltration of water, which would seriously affect the authenticity of the data. Chinese patent: "Manufacturing method of a rock sample", (Application No.: 201110002099.5) discloses a technical scheme that uses rock sample fragments to make test blocks, but when carrying out shearing, splitting and point load tests, it cannot Ensure that the failure surface completely passes through the original rock blocks, resulting in data distortion.

Contents of the invention

The invention provides a method for repairing defective rock samples in rock tests, which is improved based on the lack of rock samples or size problems during engineering tests, reducing batch collection and drilling of rock samples, and repairing incomplete drilling samples and construction processes Irregular rock samples improve utilization.

The technical scheme that the present invention takes is:

A method for repairing defective rock samples in rock tests,

Step 1: Select incomplete rock samples and rock samples with insufficient size that can no longer be subjected to shear test and splitting test, and clean and remove ash from the rock samples;

Step two:

Prepare K39 crystal resin; within 35°C-45°C (in a warm water bath), prepare according to the following weight ratio: defoamer 0.2%-0.8%, accelerator 0.3%-0.5%, hardener 0.6%-1% , after weighing the resin according to the needs, add in order according to the weight ratio: accelerator, hardener, defoamer, and add while stirring at intervals of about 20s;

Step 3: Pour the stirred resin into a mold that has been cleaned and coated with lubricating oil until the surface of the mold is covered with resin, then put the defective rock sample described in step 1 into the mold, and finally add resin to the mold. Predetermined size, waiting for its curing;

Step 4: Take the mold 1 to 2 hours after the resin is cured, and then polish the surface of the demoulded rock sample;

Through the above steps, the repair of defective rock samples for directional damaged rocks is completed.

For the splitting test, in the process of selecting rock samples, make full use of the rock mass under the same lithology and geological environment. For shear tests, the sample was appropriately reduced in length on the same core and then bulk filled with resin. The defect rock sample repairing method in a kind of rock test of the present invention, technical effect is as follows:

1) For the splitting test, resin is used to fill the incomplete rock sample, which reduces the requirements for the size of the rock sample without affecting the experimental results. For example: in the shear experiment, the length of the rock sample is required to be 50mm. After filling, it is only necessary to control the effective shearing length at about 30mm to meet the shearing requirements.

2) In the process of drilling rock samples, the rock mass under the same lithology and geological environment can be fully utilized. For shear tests, the sample was appropriately reduced in length on the same core and then bulk filled with resin. More rock samples of the same nature can be produced. After reducing the requirements on the size of the rock samples, when preparing samples in a small area, intensive preparation of rock samples of the same length can reduce the discreteness between rock samples.

3) During the shear test, the requirements for the flatness of the rock mass are very high, and usually the end of the rock mass must be smoothed before the test. There will be certain difficulties when processing and grinding rock mass with relatively high hardness. When the resin is used to fill and lengthen the irregular rock sample at the end, it can control and ensure the initial flatness, and it is also easy to grind.

4) Although during the shear test, when dealing with rock samples of insufficient size, a steel sheet will be placed at the bottom of the test base, but due to the incomplete bonding between the steel sheet and the rock sample, the shear Misalignment is easy to occur during the test, so there is a large error in the deformation of the displacement. But when resin is used for full bonding, this effect and error can be eliminated.

5) Resin is used to fill incomplete rock samples, which is convenient when drilling cores, even if there are defects on both sides of the drilled samples when the rock raw materials are insufficient. As long as the splitting path of the rock sample is not affected, it is possible to drill more rock samples for the splitting test.

6) It is required to define the minimum size corresponding to the original rock block. When performing a shear test, only a short part (the main shear plane) is required, and the remaining part is filled with resin to ensure the completion of the test. To ensure that the area of the original rock block is greater than or equal to the shear plane, its thickness should also ensure that the shear plane will not exceed its range. The splitting test also does not need a complete rock sample, and the test can be completed by ensuring that the rock mass of the splitting part is complete.

detailed description

A method for repairing defective rock samples in rock tests, comprising the following steps:

step one:

In the project engineering, the incomplete rock samples and rock samples with insufficient size that are considered to be no longer suitable for shear test and splitting test were selected, and the part of the rock samples was cleaned and deashed to prepare for subsequent sample preparation.

Step two:

Resin needed to pair missing and undersized rock samples. The specific steps are: ①, wear disposable gloves; ②, prepare colorless and transparent K39 crystal resin, colorless and transparent defoamer, colorless and transparent hardener, blue accelerator and syringe measuring device; ③, Prepared at 35°C-45°C (in a warm water bath) as follows: 0.2%-0.8% defoamer, 0.3%-0.5% accelerator, 0.6%-1% hardener. (the percentage is proportioned according to the weight of K39 crystal resin)

Defoamer: polyoxyethylene oxypropylene glycerin; accelerator: dimethylaniline; hardener: dibenzoyl peroxide.

After the model is made, when the temperature of the curing environment is too low, the amount of hardener added can be increased to about 1% in order to speed up hardening. When the indoor curing temperature is high, the content of hardener should be reduced to prevent cracking due to the exothermic hardening. For example, 0.6% is enough; the content of other defoamers and accelerators and other reagents can meet the hardening requirements by ensuring a medium percentage.

For example, to make a complete rock sample (100mm*50mm) with crystal resin and weigh 220g, the required additive content is:

Accelerator: 220g x 0.4% = 0.88g

Hardener: 220g×0.8%=1.76g

Defoamer: 220g×0.5%=1.1g

In the same way: according to the degree of defect of the rock sample, after weighing the resin, add accelerator, hardener, and defoamer in order according to the above weight ratio, with an interval of about 20 seconds, and the stirring must be uniform. It can be guaranteed that in the process of linking the rock mass, it will not penetrate into the rock mass and affect the strength of the rock mass, and will not fall off and affect the experimental process.

Step three:

Fill the mold with resin to make test rock samples of standard size. Pour the stirred resin into some molds that have been cleaned and coated with lubricating oil, then pour the mold surface is covered with resin, put the defective rock samples into the mold, and finally add resin, to Stop after the predetermined size (the standard shear size is generally 50mm*50mm, the shear rock sample can be adjusted according to the specific test plan and then made according to this method), and wait for it to solidify. The role of adding lubricating oil is to ensure that the resin and the mold are not closely combined during the demoulding process, which will affect the integrity of the rock sample. Makes demoulding relatively easy too.

Step four:

The mold can be taken after 1 to 2 hours after the resin is cured. Then, the surface of the demoulded rock sample is polished to prevent the effect on the strength of the rock sample from the structure and affect the subsequent shear test and splitting test. Clean the surrounding area of the rock sample after demoulding to avoid the influence of the resin on the authenticity of the properties of the rock sample in the split test and shear test.

In the conventional rock shear test, in order to obtain the shear strength of a certain part of the rock mass and reduce the randomness and discreteness of the rock physical properties due to different positions and different depths, it is best to make the properties of the rock samples tested have the same difference. big. On the one hand, the discrete type can be reduced; on the other hand, in the absence of rock samples, the length of the rock samples for testing can be reduced, and the above repair method can be used to standardize them without affecting the test results. That is to say, for the shear test, in the process of selecting rock samples, the rock mass under the same lithology and geological environment can be fully utilized, and the length of the rock samples can be appropriately reduced for the same core, so that relatively satisfactory test results can be obtained.

For the split test, it is to obtain the tensile strength of the rock. During the test, splitting was carried out on the diameter section of the rock sample, and the actual force acting was also the thickness of the section. Based on this, the above repair method is used to test some rocks with uneven surface or direct defects (such as the residual part after core drilling, but the splitting surface is intact). On the one hand, the rock can be fully utilized, and on the other hand On the one hand, the same part of the rock mass can be used for other physical and mechanical experiments, and the remaining part can be used for tensile tests, so that the data authenticity and comparability of the tested rock mass can be achieved.

Claims (2)

1. the defect rock sample method for repairing and mending in a kind of rock test, it is characterised in that comprise the following steps：

Step one：Selection cannot carry out the incomplete rock sample and the rock sample of undersize of shearing test and diametral compression test again, and right The rock sample carries out cleaning ash disposal；

Step 2：Prepare crystal resin, weigh up as needed after resin, carry out order addition by weight proportion：Accelerator, hardening Agent, defoamer, and stir while adding；

Step 3：The resin being stirred first is poured into the mould for cleaning out and filling lubricating oil, until die surface is all stained with After full resin, the rock sample of defect described in step 1 is put into mould, resin is finally added to predetermined size, waits It solidifies；

Step 4：The modulus after 1 ~ 2 hour after resin solidification, then appearance polishing is carried out to the rock sample after the demoulding；

Defect rock sample is completed by above-mentioned steps to repair；

For rock shearing experiment, the rock sample property tested is more or less the same, and during choosing rock sample, makes full use of same Rock mass under individual lithology and geological environment, and to reducing rock sample length on same core；

For rock cleavage experiment, carried out when being cleaved in process of the test with the diameter section of rock sample, actual loading effect is also this Individual section thickness；Residual fraction is used for carrying out tensile test.

2. the defect rock sample method for repairing and mending in a kind of rock test according to claim 1, it is characterised in that at 35 ~ 45 °C It is interior, prepared by following part by weight：Defoamer 0.2%-0.8%, accelerator 0.3%-0.5%, curing agent 0.6%-1%.