The Law Of Stress And Energy Transfer In Space Drilling And Blasting Excavation Of Deep Urban Rock Formations

China's urban underground space construction scale and growth rate have ranked first in the world,but shallow(within 50 meters)development is still the mainstay,and it is difficult to support sustainable urban development.Therefore,the development of deep underground space is the development trend of cities.Most of the geological environment in the city below 50 m is rock space.With the increasing number of drilling and blasting excavation engineering cases,the understanding of the law of stress transfer and vibration energy propagation and dissipation in deep urban rock formations is relatively scarce.Therefore,it is extremely necessary to study the stress and energy transfer law of deep urban rock space drilling and blasting excavation.This paper investigates and analyzes the distribution characteristics of rock and soil in the deep underground space of the city.Relying on the project between Fuhua Road Station and Xietaizi Station of Chongqing Rail Transit Line 18,using argillaceous sandstone as a typical rock sample,it has passed laboratory mechanical tests,numerical simulation and On-site monitoring and other means analyze its mechanical characteristics and vibration transmission characteristics,study its stress influence range and vibration transmission range,and conduct research on the influence mechanism of engineering construction on existing buildings(structures).The main research results are as follows:(1)Investigate and analyze the characteristics of the geological environment in the deep part of the city and the distribution characteristics of buildings under different buried depths.(2)Analyzed the factors affecting the deformation of surrounding rock,and carried out research on three geological factors of confining pressure,structural angle and damage degree of surrounding rock in view of the stress and vibration energy transfer law of deep urban rock formation in space drilling and blasting.(3)By applying 50%,70% and 90% uniaxial compressive strength static loading to the sample,and then carrying out the wave speed test,heat conduction test and penetration test,the difference between the test results and the undamaged sample is analyzed,and the wave speed is studied.,The relationship between thermal conductivity and permeability coefficient and the damage degree of surrounding rock.(4)The stress transfer process is studied in two phases: construction period and operation period.Conventional mechanical tests are carried out on typical argillaceous sandstone samples to study the deformation and failure characteristics of typical argillaceous sandstone samples;different enclosures are developed for typical argillaceous sandstone samples.Press triaxial compression creep test to study the creep mechanism and determine the long-term strength.Based on the Hoek-Brown strength criterion,the rock mechanical parameters are estimated,and the rock mechanical parameters of argillaceous sandstone are substituted into the formula calculation,and the rock mass uniaxial compressive strength,uniaxial tensile strength,elastic modulus and shear strength parameters(cohesive Mechanical parameters such as force and internal friction angle).(5)Carry out the SHPB dynamic impact test.By analyzing the test results of the rock sample with 30 degree,60 degree and 90 degree angle structural surface damage,the vibration attenuation effect of the structural surface of different angles is studied,and the maximum vibration velocity of the rock sample and the structure of different angles are obtained.The relationship between the maximum vibration velocity of the rock sample and the blast center distance is analyzed through the field monitoring of blasting vibration,and the relationship between the maximum vibration velocity of the rock sample and the blast center distance is obtained.Finally,through the superposition of linear functions,the relationship between structural planes at different angles,blasting center distance and the maximum vibration velocity of the rock sample is obtained through analysis,which can reflect the influence range of vibration transmission.(6)Relying on the demonstration project between Fuhua Road Station and Xietaizi Station of Chongqing Rail Transit Line 18,using ANSYS finite element software for modeling,and then using FLAC3 D finite difference software combined with rock mass mechanical parameters to compare the newly built chamber with the existing Numerical calculations are performed on the chamber working condition models with different azimuth angles and diameters.Through the numerical calculation results,the deformation of the vault and side walls of the existing chamber under different azimuth angles and distances between the new chamber and the existing chamber is analyzed,and the stress transfer influence range of the new chamber excavation is summarized and analyzed.