| A series of geological hazards are related to the in-situ stress,such as the large deformation of the surrounding rock,floor water inrush,rock burst,roof caving and so on.The in-situ stress has a huge impact on the stability of engineering.The majority instability of underground engineering is caused by the large deformation of the surrounding rock,which is resulted in the stress redistribution during excavation.More importantly,the initial stress field plays an important role in the redistribution of stress,which is the basis of analysis and calculation in the process of excavation and support of underground engineering.The in-situ stress is one of the important factors that affect the safety of construction and the safety of the project.The factors and sources of the in-situ stress is complicated,and the distribution of in-situ stress is complex and changeable in crustal rock masses.Even in the same area,the stress state of different points may be very different.Therefore,in order to understand the stress state of a region and predict the influence of the rock masses on the construction and excavation,the in-situ stress measurement must be carried out.Through the in-situ stress measurement,the magnitude and direction of in-situ stress in engineering areas can be accurately understood,which will provide technical support for engineering design and construction.This paper is based on the project of "The in-situ stress measurement of rock mass in Yellow three section of Qinling Mountains tunnel of the Han to the Wei River in Shaanxi Province".The main research contents are as follows:(1)Collected a lot of information and documents.On the basis of research and analysis,the basic concepts,the main influencing factors and stress distribution were elaborated.The regional division of stress field in China,the stress characteristics of Shaanxi province and its adjacent areas were further clarified.(2)Based on the analysis of the domestic and foreign research on in-situ stress measurement,combining the engineering conditions,the borehole radial deformation method and hydraulic fracturing method were chosen as the method of in-situ stress measurement of Yellow three section of Qinling Mountains tunnel.The two methods were studied in detail from the aspects of test principle,main equipment and test procedure.(3)The borehole radial deformation method was used to measure the in-situ stress of HZK14 test section,while the hydraulic fracturing method was used to measure the in-situ stress of the HZK06 test section and the HZK09 test section.Finally,the test results were reasonably analyzed. |
