Tunnel Anchor Anchor Body Mass Concrete Temperature And Temperature Stress Study

The technicians have done a lot of research on the temperature control of mass concrete in bridge engineering,but most of them focus on the 0#section of the main beam,the pier cap and the gravity anchor,etc.,and the geotechnical package for the tunnel anchor body.The special structure,the results of temperature control research are few,and whether the current standard temperature control indicators are applicable to the mass concrete of the anchor body is for further study.Based on the Chongqing Taihong Yangtze River Bridge as the engineering background,this paper studies the distribution law of temperature and temperature stress of large-volume concrete in tunnel anchor anchor body.The main work and achievements are as follows:(1)Using the finite element software to simulate the construction process of the mass concrete of the anchor body of the project,determine the stratified block construction plan and pipe cooling parameters of the mass concrete;embed the temperature sensor on the construction site,after the concrete is poured The temperature and test of the anchor plug body were carried out.It was found that the temperature peak reached the concrete about 1.5d after pouring,which was 0.5d?1.0d earlier than the peak time of the similar project,and the ambient temperature inside the cave was about the environment outside the cave.0.7 times the temperature.(2)Sensitivity analysis of the temperature control parameters of the mass concrete of the anchor body of the project,it is found that for every 5? increase of the mold temperature,the temperature peak rises by about 3?,and the time of its occurrence is about 6h ahead,and the stress peak rises.About 0.4 MPa;for every 40kg/m3 of cement content in concrete,the temperature peak is reduced by about 3?,and the time of its occurrence is delayed by about 12h,and the stress peak is reduced by about 0.3 MPa;compared with ordinary cement,the temperature peak of medium and low heat cement is used.Reduced by 4.6? and 14.9?respectively,the stress peak decreased by about 0.4 MPa and 1.51MPa;the thickness of the casting was reduced from 4 m to 2 m,and the temperature peak decreased by ouly 1.8?,but the stress peak decreased by 1.06 MPa;the surface convection coefficient decreased by 10 kJ/(m2·h·T)The temperature peak increases by about 1 ? and the stress peak decreases by 0.35 MPa.These data are different from the variation rules of temperature control parameters of mass concrete piers,anchors and other large-scale concrete.The mass-concrete concrete of tunnel anchor anchor body should be formulated with temperature control parameters that are different from the current specifications.(3)By establishing a finite element model to compare the two different boundary conditions of tunnel anchor and gravity anchor,it is found that although the lateral soil layer has certain restraining effect on the anchor plug body,it does not increase the internal temperature peak of the concrete,and the tunnel The favorable factors for the small change of the ambient temperature in the anchor anchor are existed.The temperature control index of the mass concrete of the anchor plug should be relaxed appropriately.The specific standard needs further study.