研究目的：地铁施工中基坑钢支撑轴力检测非常重要，关系到基坑的安全。目前施工现场是定期使用频 率读数仪来检测轴力变化。其缺点是：对轴力不能实时监测，压力超限情况下不能立即报警，同时传统读数仪 采用高压激振方式容易损坏轴力计。本文介绍一种基于TI公司低功耗单片机MSP430F149为控制核心的轴 力检测系统，采用低压扫频方式实时对钢支撑进行监测，从而保障基坑安全。 研究结论:通过系统设计和施工现场试验，得出以下结论：( 1)该系统通过低压扫频激振的方式可以实现 对传感器钢弦产生振动，起到和高压激振同样的效果，能够对轴力计进行检测，且能够减少对传感器的损坏; (2)通过和频率读数仪读数结果进行比较，该设计能够实现对轴力计频率的准确读取，同时能够对轴力变化 实时监控，提高施工工程中基坑安全预警效果，从而保证基坑的安全;（3)该研究成果可在深基坑支护监测方 面推广应用。

Research purposes ： Monitoring of axial force of steel bracing of foundation pit in subway construction is very important，which has significance to the secure construction witli pit. At present，it use the frequency meter to detect changes of tlie axial force in the construction site. Its disadvantage is not real - time monitoring，not alarm immediately overrun pressure. At the same time，the traditional reading meter adopts high voltage excitation mode，easy to damage the axial force meter. This paper introduces a kind of axial force detecting system based on low power microcontroller MSP430F149 of TI Company as the control core. The system has the function of real - time monitoring of t!ie axial force to steel bracings. Research conclusion ： Through the system design and the construction scene test， the following conclusions are obtained ： (1) The system can realize vibration to steel string of sensor by the way of low - voltage with frequency，the same effect of by the way of high - voltage wit!i frequency can monitor axial force meter，and can reduce the damage to the sensor. (2 ) Through comparison of the reading results with frequency reading meter， the design can realize the accurate reading of frequency of theaxial force meter，at thesametime，it can monitor theaxial force changes in real time，to improve the effect of foundation construction engineering safety early warning，so as to ensure the safety of foundation pit. (3)The research results can be applied in monitoring of deep foundation pit support.