第三系半成岩区滑坡变形特征及处治措施研究——以云南倘甸一公路滑坡为例

Research on the deformation characteristics and treatment measures of landslides in the tertiary semi-diagenetic area——Taking the landslide of Rangdian Highway in Yunnan as an example

第三系地层受沉积环境和沉积时间影响,大多存在胶结差、岩性软、易崩解等不良工程地质特性,给工程建设带来严重病害。以云南倘甸2015年一处公路滑坡案例为研究对象,综合滑坡区地形地貌、地层岩性、地质构造与地震、土力学试验所得的岩土力学参数以及水文地质条件等工程地质环境条件已有勘察成果,查明滑坡变形特征及成因,由此提出滑坡处治设计方案。结果表明:滑坡体平面空间呈馒头形状,为第三系含砾粉质黏土夹黏土岩地层构成的土质边坡,土层松散,力学强度低,极易产生滑坡。滑坡现状为边坡整体下滑变形,拱形格防护结构已完全破坏,坡体上发育有无数的张拉裂缝和鼓胀裂缝;由于滑坡地层松散,滑坡体上裂缝发育,滑坡体进一步失稳下滑的范围和规模将逐步扩大。归纳查明滑坡发生的基础条件是岩层性质和水文条件,诱发因素为人类工程活动。采取的处治措施主要针对第三系半成岩地层边坡防护设计,按照“排水优先、强腰固脚、放缓坡率、生态防护、旱季施工”的指导思路进行。

Affected by the depositional environment and deposition time,most of the Tertiary strata have poor engineering geological characteristics such as poor cementation,soft lithology,and easy disintegration,which bring serious diseases to engineering construction.Taking a road landslide case in Rangdian,Yunnan Province in 2015 as the research object,the engineering geological environmental conditions such as the topography and landform,stratigraphic lithology,geological structure and earthquake,soil mechanics parameters obtained from soil mechanics tests,and hydrogeological conditions in the landslide area were comprehensively analyzed.According to the existing survey results,the deformation characteristics and causes of the landslide were identified,and the landslide treatment design scheme was proposed.The results show that the plane space of the landslide body is in the shape of steamed bread,and it is a soil slope composed of tertiary gravel-bearing silty clay sandwiched with clay rock.The soil layer is loose and the mechanical strength is low,which is very easy to cause landslides.The current situation of the landslide is that the slope is sliding and deformed as a whole,the protective structure of the arched lattice has been completely destroyed,and there are numerous tension cracks and bulging cracks on the slope body.Due to the loose strata of the landslide and the development of cracks on the landslide body,the scope and scale of further instability and slipped of the landslide body will gradually expand.It is concluded that the basic conditions for the occurrence of landslides are the properties of rock formations and hydrological conditions,and the inducing factors are human engineering activities.The treatment measures adopted are mainly aimed at the slope protection design of the tertiary semi-diagenetic strata,whichis carried out in accordance with the guiding ideas of“prioritizing drainage,strengthening waist and feet,slowing down slope rate,ecological protection,and construction in dry season”.