Preparation method of true triaxial sample for reflecting occurrence characteristics of weak intercalated rock mass

Abstract

The invention provides a preparation method of a true triaxial sample reflecting occurrence characteristics of a rock mass containing a weak intercalated layer, which comprises the following steps: firstly, obtaining a stress state of a primary rock, then preparing cuboid rock samples with different combination angles in batches, and polishing a rock structural surface of the sample based on scanning data of a field rock structural surface to obtain a true triaxial sample; adjusting the water content of the weak intercalated layer obtained on site or the weak intercalated layer similar material prepared by uniformly mixing the weak intercalated layer according to the proportion to the required water content, maintaining, adjusting the rotating support to the required angle, sequentially adding the materials into a mold, and finally loading the sample to a primary rock stress state and carrying out later-stage standardization treatment. According to the method, by adjusting the splitting and grinding angle of the mother rock, setting the mold with an inclinable angle and setting different thicknesses of the weak intercalated layers, the weak intercalated layer-mother rock composite samples with different occurrence states and thicknesses are prepared, the weak intercalated layers are distributed more uniformly, and the obtained weak intercalated layer-mother rock composite true triaxial sample is easy to form and has good mechanical properties. And the method is more in line with the actual spatial topology distribution state of the weak intercalated layer on site.

Description

technical field [0001] The invention relates to the technical field of geotechnical engineering, in particular to a method for preparing a true triaxial sample that reflects the occurrence characteristics of rock masses containing weak interlayers. Background technique [0002] At present, the hydropower, mine and tunnel projects under construction in our country are complex due to the complex geological structure and there are many different types of weak interlayers in the rock mass. The weak interlayer is the weak rock mass in the rock mass. Under the tectonic action, the original rock is altered due to shear dislocation, and the structure is damaged, which is easily susceptible to water softening and weathering. It is a thin banded geotechnical system with strong ductility and high risk. During the construction process, the large-scale high in-situ stress unloading and excavation disturbances make weak interlayers and rock masses containing weak interlayers prone to var...

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Problems solved by technology

[0005] 1. The patent application number 201420140161.6 discloses a four-column geotechnical material with bedding standard test piece batch pressing mechanism and operation method, the method is to press the test piece with bedding by using different angles of punch and die , this method can press multiple samples at one time, and the sample preparation efficiency is very high, but the loading stress cannot be precisely controlled, and the stress may be uneven due to simultaneous pressing of multiple samples, and the range of inclination angle of the prepared samples is also limited. Shortcomings

[0006] 2. The patent with the application number 201820844669.2 discloses a combined mold for standard cylindrical specimens with interlayers at different angles and its operation method. This method combines three annular molds to make composites containing sandwiches with different inclinations and thicknesses, but With this method, the same set of molds can only produce a sample with one inclination angle and thickness. When there are different requirements for the inclination angle and thickness of the sample, it is necessary to customize a matching mold. Therefore, this method has a single function and high energy consumption.

[0007] 3. The patent application number is 201811200989.5, which discloses a supporting device for the production of weak interlayers with adjustable thickness of the original rock structural surface and direct shear test. This device can solve the problem of making and laying the weak interlayer of the existing original rock structural surface Difficult and difficult to adjust the thickness of the weak interlayer, but the uniformity of the laid weak interlayer is difficult to control

[0008] 4. The patent application number 202121583378.0 discloses a combined mold device for making conventional direct shear test specimens of composite rock mass. This combined mold device enriches the convenience of making composite samples with different cemented surfaces and avoids the traditional The damage caused by on-site drilling and cutting sampling to the sample and the uncertainty of the interface distribution requirements, but the loading system of the device is relatively simple, and the loading stress and time cannot be well controlled

[0009] There are still some shortcomings in the composite rock sample made by the above method. It cannot simulate the real stress state of the rock mass with weak interlayer under the plateau rock stress well. The interlayer dip angle and thickness of the prepared sample are not easy to control. The distribution is not uniform enough, which affects the accuracy of the test results

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