密排横向管幕理论分析研究

Theoretical analysis of horizontal pipe curtains with tight rows

大直径管幕超前预支护对暗挖工程中的变形控制具有积极作用,管幕的布置形式可分为纵向与横向两种。以北京平安里地铁车站工程及其实测数据为基础,探索性地将带有锁扣的横向管幕简化为弹性薄板,继而对比分析了采用弹性薄板理论和连续梁理论的计算结果;最后,针对导洞开挖跨度、上覆土层厚度、钢管壁厚以及钢管内浆体弹性模量等参数进行了影响分析。结果表明:①无论是在变形趋势,还是在最终变形量上,弹性薄板理论的挠度计算结果都与实测数据吻合性较好,而简支梁与弹性地基梁理论仅最终变形量与实测结果较为吻合;②在相同荷载条件下,弹性薄板理论计算得到的最大弯矩值稍大于简支梁的计算结果,但两者相差不超过10%;③钢管壁厚和浆体弹性模量对管幕变形的影响较小,而开挖导洞跨度和上覆土层厚度对管幕变形与弯矩的影响较大。

The pre-support of large-diameter pipe curtains plays an active role in controlling the deformation of excavations,and the layout of the pipe curtains can be divided into vertical and horizontal types.Based on the measured data of Pinganli metro station in Beijing,the horizontal pipe curtains with lock are simplified into the elastic thin plates,and the results of the elastic plate theory and the continuous beam theory are compared and analyzed.Finally,the influences of excavation span,height of overburden,wall thickness of steel pipes and elastic modulus of grouting materials are analyzed.The results show:(1)The results of the settlement calculation of the elastic thin plate theory are in good agreement with the measured data both in the settlement trend and in the final settlement,while the calculated results of the simply supported beams and the elastic foundation beams are only in good agreement with the measured ones in the final settlement.(2)Under the same load conditions,the maximum bending moment calculated by the elastic thin plate theory is slightly larger than that of the simply supported beams,but this difference is not more than 10%.(3)The elastic modulus of slurry and the thickness of the steel pipe wall have small effects on the settlement and bending moment of the pipe curtains,while the excavation span and the height of overburden have great influences on the settlement and bending moment of the pipe curtains.The research results may provide a new way to simplify pipe curtains into homogeneous elastic thin plates for calculation,and provide the theoretical support for design of the pipe curtains.