震后公路边坡崩塌地质灾害形成机理分析

震后崩塌是强震作用下形成的一类分布广泛、震裂变形严重、潜在威胁大的次生地质灾害。为了较为深入系统地分析其形成机理,本文结合对映秀至卧龙公路沿线震后公路边坡崩塌地质灾害详细调查和115条实测剖面的分析,首先把震后公路边坡崩塌地质灾害从孕育形成到失稳破坏的演化发展过程分为4个阶段,即原始结构面的形成阶段、潜在变形体的形成阶段、震裂岩体的形成阶段和失稳破坏阶段。在此基础上,分析认为震后公路边坡崩塌地质灾害的形成机理可归纳为震裂-滑移式、震裂-倾倒式、震裂-溃屈式和震裂-错断式4种模式,研究成果为灾后公路重建和防灾减灾提供了有力参考。

ANALYSIS OF FORMATION MECHANISMS ON HIGHWAY SLOPE COLLAPSE AFTER WENCHUAN EARTHQUAKE

The unexpected strong 5.12 Wenchuan Earthquake caused great economic losses and casualties and affected a large area of Sichuan.After the Wenchuan Earthquake,there were severe secondary geological disasters on the highway from Yingxiu to Wolong.the traffic was usually snarled,which influenced the highway safety operation and reconstruction seriously.What’s more,the post-earthquake collapses are a secondary geological disaster with the wide distribution,severe shatter and large potential threat under the action of strong earthquake.This paper analyzes the formation mechanism on post-earthquake collapses in depth.It takes the highway from Yingxiu to Wolong with more post-earthquake collapses as the research object.It combines with predecessors’ achievements on Wenchuan Earthquake.It is based on the detailed survey about the post-earthquake collapses of slopes near the sides of the highway from Yingxiu to Wolong and 115 profiles.There are four stages of post-earthquake collapses from start to finish.Namely,they are the original structure,potential variable body,shattering rock and collapse.On this basis,the formation mechanism on the post-earthquake collapses of highway slopes can be described as four models including shatter-slip collapse,shatter-dump collapse,shatter-burst collapse and shatter-offset collapse.Because of the complex rock mass structure,there are usually two or three collapse formation mechanisms with a certain way together in the collapse disasters and the formation mechanisms change from one to another during the constant process of evolution and development.However,among them,there is one mechanism which first happed as the major in the collapse.These reveal that the mechanical mechanism of the slope rock mass changes, and determines the final damage forms and features of post-earthquake collapses.The paper makes expatiation of their formation mechanisms.These results provide a powerful reference for highway reconstruction and disaster prevention and mitigation.At the same time they also provide the technical support for such the problems including disaster reduction countermeasures of transportation infrastructure under the influence of the earthquake and the methods for dealing with to clear the road blocked by the collapse,highway slope collapse disasters prevention in the mountainous area and earthquake disaster prevention highway recovery.