云南膨胀土工程边坡滑坡机理分析

Mechanism Analysis of Slope and Landslide in Yunnan Expansive Soil Engineering

地表浅层膨胀土在大气影响下反复吸水膨胀失水收缩,产生大量干缩裂隙并显著降低其强度和完整性,直接在此类土层上填筑路堤或开挖路堑极易引起路堤边坡过大变形甚至失稳破坏,严重影响工程安全。基于此,文章以云南某中弱膨胀土地区的工程边坡为研究对象,对该滑坡的机理进行了分析。结果表明,在云南等膨胀土广泛分布区,地层当中大量存在强度极低、结构破碎且埋藏较浅的软弱夹层,在工程边坡开挖或填筑过程中极易进一步贯穿形成滑动面。在工程勘察阶段查明软弱层的强度和位置,将软弱层纳入边坡的分析模型中合理计算稳定性,同时施工过程应注意防止水流入渗,避免软弱层的强度进一步弱化,是防止此类膨胀土工程滑坡的关键。

Shallow expansive soil on the surface repeatedly expands by absorbing water and shrinks by losing water under the influence of the atmosphere, resulting in a large number of dry-shrinkage cracks and significantly reducing its strength and integrity. Filling embankments or excavating road cuttings directly on such soil layers can easily cause excessive deformation or even instability and damage of embankment slopes, which seriously affects engineering safety. Based on this, this paper takes the engineering slope in a moderately weak expansive soil area in Yunnan as the research object, and analyzes the mechanism of the landslide. The results show that there are a large number of weak interlayers with extremely low strength, broken structure and shallow burial in the expansive soil widely distributed areas such as Yunnan, and it is easy to further penetrate to form the sliding surface during the excavation or filling of engineering slopes. The key to prevent such expansive soil engineering landslide is to identify the strength and location of the weak layer in the engineering investigation stage, and to reasonably calculate the stability by incorporating the weak layer into the slope analysis model. At the same time,the construction process should pay attention to preventing water infiltration and avoiding the further weakening of the strength of the weak layer.