Abstract
In the aspect of stability analysis of tunneling engineering, geomechanical model test is an important research method. A similar material is the prerequisite for the success of geomechanical model test. In the field of major engineering applications, a variety of similar materials are prepared for different geological conditions of surrounding rock and applied in some major engineering. With the use of standard sand, fine sand, and silt clay as materials, similar materials for weak surrounding rock were developed. Based on the orthogonal design method, through the direct shear test, the range analysis and variance analysis of various factors affecting the physical and mechanical parameters of weak surrounding rock are carried out. The results show similar material can meet the requirements in weak surrounding rock. Standard sand is the key factor that influences the internal friction angle of similar materials, and silt clay is the key factor affecting the cohesion of similar materials. Similar materials can meet the elastic modulus and severe requirements of the weak surrounding rock and can be used for the weak surrounding rock engineering. The new type of similar material configuration is widely used in shallow buried tunnel entrance section and urban shallow buried excavation engineering, in addition to tunnel engineering in loess stratum, and the problems of engineering design and construction are solved through geomechanical model test.
Highlights
According to the study on geomechanical model test of the ratio of similar material, selecting standard sand, fine sand, and silt clay as similar material can reduce the number of tests by using orthogonal test method
In the optimization test scheme, the ideal ratio of similar materials and set of the standard sand percentage, silt clay, and similar materials accounted for similar material percentage of 2 with a set of 3 factors, each factor level obtained by range analysis of laboratory tests on specimens of the results
The conclusions are as follows: (1) The intersection test analysis shows that silt clay has an obvious influence on the cohesive force of similar materials, and the standard sand has an obvious influence on the internal friction angle of similar materials
Summary
It is impossible to develop a similar material that completely reflects the physical and mechanical properties of the prototype. The main similarity criteria should satisfy the specific conditions of the experiment In the test, it needs to satisfy similar deformation condition of the strength to satisfy the similar deformation property of the model as possible. Based on the elastic modulus, Poisson’s ratio, gravity, and various strength parameters, different proportioning tests are carried out to compare the material proportions that meet the requirements of similar proportions. Similar materials should be selected and configured for the purpose of testing. Each test should be carried out with similar material configuration, and similar material cannot be reused, so it requires similar material price to be lower and ensure economy test
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