The Regional Stress Characteristics And Fault Activity Analysis Of The Mid-segment Of Tan-lu Fault Belt

The study of regional CRustal stress characteristics and fault activity in the mid-segment of Tan-Lu Fault belt is of great significance for geological disaster prevention and mitigation in North China.This paper collects the geological background of the mid-segment of Tan-Lu Fault belt and combines the previous research of tectonic stress field of this region.By a variety of means such as drilling television,hydraulic fracturing and AHP based on GIS platform,this paper analyses the characteristics of structural plane,the stress variation law of fault belt,the fault activity partition and the slip-tendency of fault in the mid-segment of Tan-Lu Fault belt.The main research results are as follows:1.There are 6 broken bands,1743 structural planes and 205 vertical CRacks showing in the borehole TV image.The average strike of structural planes is101.84°,the dip angles of structural planes center on 50°⁷0°,the strike of structural planes changes from N45°E to N45°W with the inCRease of the depth,the RQD of the borehole rock mass is 89.43%.Through the calculation of depth of abrupt change of the occurrence and the friction coefficient of structural planes,we find that the NW-trend structural planes in 345³60m are more likely to slip compared with the maCRo rupture in the study area,and the existence of concealed fault is found at this depth.2.The range of the stress ratio K_maxax in the mid-segment of Tan-Lu Fault belt is1.25².20,while the range of K_minin is 0.60¹.25,and the stress ratio K reaches the maximum value near WeiFang in the northeast of the study area.The stress field in the mid-segment of Tan-Lu Fault belt is mainly characterized by the stress state of the reverse fault,and the local area shows the characteristics of the strike-slip fault according to the fault classification of Anderson.The friction coefficient of the fault in the mid-segment of Tan-Lu Fault belt ranges from 0.1⁰.4 which is less than that obtained by Byerlee in the laboratory.This indicates that the faults in the mid-segment of Tan-Lu Fault belt are currently in a relatively stable state,and the ratio of shear stress and effective stress of NW-trend fault is greater than that of the NE-trend fault.3.The calculation results of the stress accumulation index?_m which are made into cloud maps are obtained based on interpolation method.The results show that the stress accumulation in the northeast and southwest of the deep part of the study area is high while the northeast of the superficial part of the study area is the stress concentration part.4.The factors affecting the fault activity are selected to construct the evaluation which is used to partition the fault activity with using the AHP based on the ArcGIS platform.The results show that the northeast and southwest part of the mid-segment of Tan-Lu Fault belt are likely to slip,and the mid-segment of Tan-Lu Fault belt is more likely to slip along the NW-trend fault in the southwest area.