Experiment Study Of Relation Between In-situ Stress And Mechanical Properties Of Surrounding Rock In Pinggu

In-situ stress is a kind of natural stress occurrence in rock mass, and has been widely used in the engineering construction. The more complex geological environment which major construction projects in the western region of China have faced, the need of advanced theory and technology in regional stability evaluation after Wenchuan earthquake, new problems appear in deep mining operation, all of these have proposed new requirements in the study of relationship between in-situ stress and mechanical properties of surrounding rock, the study of this subject is of great significance.So far, the comparability and consistency of the data,which is about the impact of the lithology, the rock mass structure, rock mechanical properties on in-situ stress, and the impact of confining pressure on the mechanical properties of rock in experiments is not high enough. Rock mechanics experiments corresponding to in-situ stress measurement is not systematic and particular enough. The impact of rock mass structure is rarely considered in the study of relationship between in-situ stress and mechanical properties of surrounding rock. To solve above problem, this thesis which used a deep borehole in-situ stress measurement in Beijing as an example, have done some study in following aspects.(1)Taken in-situ stress measurement with the depth of the borehole systemly, and analyzed the reliability of measurement results.(2)Samples were taken in the same depth with in-situ stress measurement, and were used in rock mechanics experiments, which are with confining pressure of OMPa, 5MPa,10 MPa,15 MPa. The rock mechanical properties were got based on above experiments.(3)Based on structural features of rock mass drilling index (RQD), the rock mechanical properties were revised to obtain the approximate rock mass mechanical properties in the site where the in-situ were measured.The thesis analyzed the relationship between the maximum horizontal principal stress, the minimum horizontal principal stress and mechanical properties of surrounding rock in Granite and Limestone. The following main conclusions have been obtained.(1)The lithology, rock mass structure, rock(mass) mechanical properties, which have interrelated and mutually influence each other, effect the shallow crustal stress state mutually.(2)The maximum horizontal principal stress, the minimum horizontal principal stress and elastic modulus of rock mass showed a positive correlation in Granite.(3)In high-isotropic rock (e.g. Granite), the correlation between measured stress and mechanical properties of rock & rock mass result of rock mechanical test is high. In low-isotropic rock (e.g. Limestone), the correlation between measured stress and mechanical properties of rock & rock mass result of rock mechanical test is low.