侧压力系数对盾构隧道接头变形及受力影响

为明确侧压力系数对盾构隧道结构接头变形及受力特性的影响规律,通过建立三维精细化数值模型,并与足尺试验进行对比验证,研究正常承载、超载及卸载情况下侧压力系数改变对接缝张开、错台及螺栓受力的敏感程度。研究结果表明：在正常承载阶段,侧压力系数的减小使得隧道结构的受荷形式更加不利,接头更易发生损坏,当侧压力系数从0.7降低至0.65、0.6时,纵缝最大张开量分别增大1.6倍和21.7倍,环缝最大错台量分别增大2.7倍和20.1倍。对比超载及卸载2种情况,卸载情况下隧道结构的纵缝张开量及环缝错台量对侧压力系数变化更加敏感。在“临界失稳状态”和“极限破坏状态”下,不同侧压力系数下的螺栓应力基本相同,表明螺栓应力水平主要由其自身属性决定,侧压力系数的减小,仅加快了螺栓屈服进程,对螺栓最终应力水平无显著影响。

Study on Influence of Lateral Pressure Coefficient onDeformationand Stress of Shield Tunnel Joints

In order to study the influence of the lateralpressure coefficient on the deformation and stress characteristic of the shieldtunnel joint, a three dimensional refined numerical modelis developed, and the full scale test is carried out.The sensitivity of the lateral pressure coefficient to the joint open,dislocation and the bolt stress under the conditions of normal load, overloadand unload is studied. The study results show that: (1) At the normal loadstage, the reduction of the lateral pressure coefficient worsens the load formof the tunnel structure, thus the joint is prone to damage easier. (2) When thelateral pressure coefficient decreases from 0.7 to 0.65 and 0.6, the maximumopen of longitudinal joint increases by 1.6 times and 21.7 times respectively,and the maximum dislocation of circumferential joint increases by 2.7 times and 20.1 times respectively. (3)The longitudinal joint open and circumferential joint dislocation under unloadcondition is more sensitive to the variation of lateral pressure coefficientthan overload condition. At the stages of critical instability andultimate failure, the bolt stresses are basically the same underdifferent lateral pressure coefficients, which shows that the bolt stress ismainly determined by its own properties, the reduction of lateral pressurecoefficient only accelerates the process of bolt yield, while has nosignificant influence on the final stress of the bolt.