斜螺栓管片接头破坏演化机理及参数影响OA

To clarify the stress characteristics and failure mechanism of inclined bolt joints in subway shield tunnel segments,firstly,full-scale tests were designed and carried out on 2 adjacent segment standard blocks based on the supporting engineering.The stress-strain development law of concrete in each part of the inclined bolt segment joint during bearing was analyzed,and the failure process of the segment joint was studied in stages.Then,a numerical model was established to compare the failure process and characteristic change laws of segment joints under 2 methods:numerical simulation and full-scale testing.The rationality of the established model was verified,and the characteristic load values reflecting the bearing capacity of each stage were determined.Finally,influence laws of concrete strength,joint voids,and bolt strength on bearing performance were investigated.The results show that the failure process of the inclined bolt joint of the segment presents a four-stage characteristic.In the cracking stage,the bolt is the main load-bearing component,and the change in stiffness curve corresponds to the failure stage.However,there is a significant spatial attenuation characteristic in the constraint effect of the bolt.The bearing capacity of the joint decreases after cracking and recovers after contacting with the outer arc surface.The compressive zone of the joint concrete gradually moves upward with the opening angle of the inner arc surface,and the inclined bolt is subjected to the greatest force and significant deformation on the joint surface,where concrete cracks first appear.The influence on the change of joint stiffness is the most significant when the concrete grade of the segment is between C50 and C60,and the improvement effect of joint stiffness is the best when the joint void is between 3 and 4 mm.At this point,selecting bolts of grade 6.8-8.8 can balance economy and bearing performance.