FAILURE PATTERN STUDY AND SECURITY ANALYSIS OF TUNNEL AFFECTED BY PILE LOAD

The stability analysis of Chaotianmen Tunnel affected by pile load is carried out by strength reduction finite element method.Interaction between pile and tunnel is a complex procedure of pile-soil-structure interaction.It contains three kinds of failure patterns:tunnel failure,pile foundation failure and lining failure.Tunnel failure and pile foundation failure are shear breakage of soil.The safety factor can be calculated by strength reduction finite element method.Six kinds of calculation schemes and sixteen kinds of pile positions are established,in order to study the influence factors of stability of tunnel by pile loading such as strength of rock mass,pile load,distance between pile and tunnel,depth of pile,etc..Through analyzing the calculation result of safety factor,it is found there are critical distance and critical depth between tunnel and pile.Pile has greatly influence on tunnel,if it is located within critical distance or critical depth,and tunnel will fail firstly.Conversely,pile has little influence on tunnel,and pile foundation will fail firstly.