基于3DEC对某输电线路新建铁塔岩质边坡的稳定性评价

Stability Evaluation with 3DEC for the Rock Slope under a Newly-built Transmission Line Tower

我国广泛分布的山区不时会遇到将输电线塔建立在危险陡坡的情形,开挖陡坡将截断原有支护结构,边坡的稳定性成为输电线路建设中的关键突出问题。以某输电线路新建铁塔岩质边坡工程为依托,在现场调研与结构面测绘的基础上,确定优势结构面,采用极射赤平投影法定性分析其潜在破坏模式,并通过3DEC离散元方法定量评价了截断原支护结构的边坡稳定性和新增支护后新建铁塔的边坡稳定性。结果表明:开挖边坡并截断锚索,会造成边坡开挖面附近产生较大变形,天然工况下边坡稳定性系数小于1,无法满足工程安全性要求;在开挖前对边坡增加锚索和抗滑桩(兼塔腿)加固支护,边坡稳定性得到明显改善,可满足工程安全性要求。

Towers of transmission lines often need to be built on the dangerous slope in the widespread mountain areas of China.The excavation activity will cut off the original supporting structure and thus destroy the initially steady state.The stability of tower slope is of great significance for the construction of transmission lines.Taking the rock slope project of a newly-built transmission line tower for the research object,on the basis of field investigation and structural plane measuring,this paper determines the preferred structure planes of rock mass.The paper adopts the stereographic projection method to analyze the potential failure mode,and uses the 3DEC numerical simulation to quantitatively evaluate the stability of the slope after cutting off the original supporting bolt,and the newly-built tower after enhancing the support.The results show that excavation activity will cause large deformation near the excavation face of the slope,and the slope stability coefficient could not meet the engineering safety requirements;strengthening the support by adding anchor cables and anti-slide piles(which can double as tower leg)before excavation activity will significantly improve the slope stability and meet the engineering safety requirements.