基于BOTDR技术的深埋岩溶土洞监测分析

岩溶洞穴发育成地表塌陷影响因素复杂。为了获得岩溶土洞监测标识区域的应力特征，在太沙基松动土压力理论基础上，对岩溶土洞发育历程中松动区竖向土压力进行了分析。松动区的空间位置由洞穴特征及其上方岩土介质的物理、力学性质决定；平面应变和非平面应变条件下，松动区竖向土压力的分布特征差异明显。根据岩溶土洞上方松动区竖向土压力的分布特征，结合BOTDR技术优点，提出应用BOTDR技术监测岩溶土洞的发育，针对光纤监测系统设计中光纤布线型式进行了分析。岩溶土洞应力场变化特征的定量研究对光纤传感技术应用于岩溶土洞监测设计提供理论依据和指导。 

Monitoring and analysis of deep buried karst soil caves based on BOTDR technology

Surface collapse of karst soil caves can be attributed to many complex factors.The aim of this work is to reveal the stress characteristics of soil caves in the marked areas being monitored. Based on the Terzaghi theory of loose earth pressure, the vertical earth pressure in the loose zone is analyzed. The results show that the location of the loose zone is decided by cave''s characteristics and physical and chemical properties of overlying media. Under plane and non-plane strain conditions, the distribution characteristics of vertical earth pressure in the loose zone are obviously different. According to the distribution characteristics of vertical soil pressure in the loose zone, combined with the advantages of Brillouin Optical Time Domain Reflectometry (BOTDR), the application of BOTDR technology to monitor the development of the karst soil cave is proposed. The layout of optical fibers in the monitoring system is analyzed. The quantitative study on the stress field of the soil cave provides a theoretical basis and guidance for the application of BOTDR to monitoring karst soil caves.