新管幕法下穿铁路既有线施工地表沉降监测

为避免新管幕法下穿铁路既有线施工所导致的轨面不平、列车晃车等铁路运营事故,以太原市迎泽大街下穿火车站通道工程为施工背景,考虑火车站内强电磁干扰环境对传统电磁、电容式传感器的影响,选用合适的光纤光栅传感器对地表沉降进行监测,设计了监测方案并搭建了监测系统,获得了施工引起的地表沉降数据,并用数值模拟方法研究了土体沉降,获得了地表横向距离沉降规律,对比论证了该监测技术的正确性和有效性。监测和计算结果表明,新管幕法施工引起的地表沉降呈漏斗状,中间大两头小,监测断面的最大沉降值为21.2 mm,在施工安全范围内。

On the ground subsidence monitoring in the construction of the currently ex-isting rail-lines under the new tube curtain method

This paper is inclined to find the regularity of the ground settlement and the escort for building up a safety monitoring system consisting of the optical fiber sensing technology,the virtual instrumentation technical system and the cloud platform technology. The purpose of such a system construction is to execute the real-time,automatic remote monitoring or supervision of the ground settlement in formulating a new pipe curtain method.And,next,in the process of proceeding with the actual on-site monitoring activities,it would be necessary to adopt the new type of fiber Bragg grating sensor by choosing up a monitoring section so as to meet the demands of the safety monitoring activities in accordance with the monitoring scheme and monitoring system by the acquired remote monitoring data in the real time. At the same time,it would be necessary and possible to explore the regularity of the soil settlement to build up a new pipe curtain method through numerical simulation so as to compare the simulation results with the actual monitoring data to prove the effectiveness and feasibility of the monitoring method. According to the actual field monitoring need of the results,the actual maximum ground settlement value is actually equal to 21. 2 mm at the monitoring section in the process of pipe jacking,whereas the corresponding numerical simulation data tends to be 15. 8 mm. The situation can be explained by the fact that the numerical simulation data is less than the monitoring data by 5. 4 mm. It can also be explained that we fail to take the account the orbit above the vehicle dynamic load caused by the subsidence effect in the simulation practice. Thus,on the whole,the surface settlement rules obtained by the above 2 methods prove to be consistent. That is,(1) The surface settlement resulted by the new tube-curtain method is funnel-shaped,with the greatest settlement of the both sides either in the middle or in the smaller sides,are of gentler settlement away from the center and faster settlement near the center;(2) In the process of the tube jacking,the jacking of the upper ones tends to have a greater impact on the surface settlement,whereas the lower jacking tend to have a smaller impact on the surface settlement.