大型土坡施工过程稳态评估及安全控制

Stability Assessment and Safety Control for Large-scale Soil Slope during Construction

依据大型土坡渐进破坏演化特征、阶段划分及稳态变化,提出其施工过程安全评估标准、控制对策及操作流程,得到以下基本结论。(1)以大型土质路堑边坡渐进破坏4阶段理论,将其施工过程安全状态划分为安全、基本安全、欠安全和不安全共4种安全等级,并根据其安全系数区间及变形破坏特征,提出相应的评估标准。(2)针对大型土坡的稳态变化提出安全控制对策及其实施流程,当Fs≥1.10时,边坡处于安全状态,可进行正常开挖;当1.05≤Fs<1.10时,施工处于基本安全状态,需暂停开挖实施加固;当1.02≤Fs<1.05时,施工处于欠安全状态,应停止开挖超前加固;对Fs<1.02的不安全状态,应提前预判并实施应急抢险工程。(3)根据某大型土坡施工安全方案比选案例研究,提出保证施工过程安全并兼顾推进施工进度的"阶段开挖、分批加固"的优化施工方案,并对各阶段安全系数取值区间、评估标准、计算精度及控制效果进行讨论。

In this paper, construction process safety assessment standards, control strategy and operation process for large-scale soil slope are studied based on its progressive failure evolution characteristics, stage division and steady state changes. The main conclusions are as follows： （1） According to the four stages of gradual failure theory for large soil cutting slope, the construction process of safety state is divided into four types of security levels, such as safety, basic safety, less safety and unsafe. Moreover, the corresponding evaluation standards can be put forward according as safety factor and failure characteristics; （2） Considering dynamic stability condition of large-scale soil slope, the relativesafety control strategy and operating process are summarized： when Fs≥1. 10, the slope is in safe status, and can be excavated; when 1.05≤Fs〈1. 10, the slope is in basic safe status, should be pause excavating, and implement reinforcement measure for excavated slope surfaces; when 1.02≤Fs〈1.05, the slope is in less safe status, should be stop excavating, and pre-reinforce immediately; when Fs〈1. 02, the slope is in unsafe status, should be predicted, and be treated with ahead of time. （2） According to the research on comparison and optimization for same large-scale soil slope construction project, the construction scheme of ＂excavation in phases, reinforcement by sections＂ is proposed, which can ensure the slope safety and fast during its construction process, and same topics as safety coefficient value, evaluation standard, calculation accuracy, and control effect of stages are discussed finally.