映秀—卧龙公路沿线汶川地震地质灾害研究

映秀—卧龙公路是汶川地震灾区距震中最近、震害最为严重的一条公路,本文对沿线地震地质灾害进行了详细的调查研究。依据震害特征,将沿线震害划分为斜坡中上部强风化岩体及土层失稳、结构面切割岩体崩滑失稳、滑坡、泥石流等4类,并分析了沿线震害发育规律。调查表明:龙门山后山断裂两侧地震地质灾害呈现显著的差异性,主要是由深大断裂的消震隔震效应,地貌放大效应,地质结构等三方面因素决定的。通过134条实测剖面分析,研究了地震失稳斜坡坡度和失稳部位。地震诱发失稳斜坡坡度在33°~84°之间,主要分布在41°~65°之间,可以认为地震诱发斜坡失稳灾害主要发生在40°以上的斜坡。斜坡失稳部位主要分布在斜坡中上部以及地貌突出部位,主要失稳部位在0.4坡高以上。从研究斜坡动力失稳的角度,将沿线斜坡划分为基岩-土层及强风化层斜坡地质结构、不利外倾结构面基岩斜坡地质结构、块状构造基岩斜坡地质结构、块碎石土层斜坡地质结构等几种地质结构模型,分析论述了各种地质结构相应的地震地质灾害类型及特点。

GEOLOGICAL HAZARDS DUE TO WENCHUAN EARTHQUAKE ALONG YINGXIU TO WOLONG HIGHWAY

The highway from Yingxiu town to Wolong town is the nearest highway to the epicenter of Wenchuan Earthquake. The geo hazards long and damage to the highway are the most serious. This paper presents a comprehensive investigation of the geological hazards due to the earthquake along the highway.Based on their characteristics,the geo hazards are divided into four types.They are instability of highly weathered rockmass and soil on the upper part of the slopes,instability of rock mass cut by geological structural surface,landslides and debris flows. It analyzes the developmental law of geo hazards along the highway. The geo hazards show significant deviations between the two sides of the back range faults at the Longmen Mountain fault zone. The reasons are the seismic isolation effect of the deep fracture,scaling effect of the landforms,and geologic structures. The slope steepness and position of seismic instabilities have been studied via the analysis of 134 geological sections. The results show that the slope steepness of seismic instabilities are distributed within the range of from 33 to 84,mainly from 40 to 65. So,it can be concluded that the geo hazards caused by the earthquake mainly took place on the road slopes steeper than 40. The failure zones caused by seismic force mainly distributed on the upside of the road slopes. The instability positions are mainly upon the parts with slope gradients more than 040.For the study of slope dynamic instability,four geologic structure models are put forward.They are rock soil and strong weathered rock slopes,rock slopes with outward inclined structural plane,massive structure rock slopes and crushed rock soil slopes. It analyzes the type and characteristics of eachof the four geologic structure models. 