川东红层区巴南广高速公路滑坡高发成因分析

ANALYSIS ON THE CAUSES OF LANDSLIDE OF BAZHONG-NANCHONG-GUANG'AN HIGHWAY IN EAST SICHUAN OF RED BEDS AREA

研究目的:巴南广高速公路位于地形地貌平缓、基岩产状近水平、构造相对简单的川东红层地区,线路修建时滑坡病害频发,其中工程造价超过10万元的滑坡达192处,工程治理费用约4亿元,严重影响了高速公路的正常建设。基于此,笔者依据咨询的这192处滑坡建立样本数据库,对滑坡高发的成因进行分析,以期能为今后类似红层区的高速公路的安全、经济修建提供借鉴。研究结论:(1)以富水粉质粘土为主的堆积体滑坡是项目区滑坡主要类型,且以小-中型滑坡为主,滑坡密度大,治理费用高,这是项目区滑坡的主要特征。(2)红层区特殊的地质环境是滑坡高发的基础,主要体现在地表广泛分布的可塑-软塑状粉质粘土和下伏的富水砂泥岩地层对工程扰动敏感,易使坡体在开挖卸荷和填方加载后,利用土岩交界面和最大剪应力形成的同生滑面产生堆积层滑坡、在近水平产状的砂泥岩中形成平推式、错落式和破碎岩质滑坡。(3)欠合理的设计对滑坡高发具有控制作用,主要体现在地质选线贯彻较差,路基填挖规模偏大而使坡体防护工程针对性差,造成大量工程滑坡的出现,且处治设计周期过长,使滑坡范围不断扩大。(4)施工方责任心欠缺,不合理的工程开挖或填方是滑坡高发的重要因素。

Research objective：Bazhong-Nanchong-Guang’an expressway is located in the gentle to-pography,rock yield near horizontal,relatively simple structure of red beds in East Sichuan area,the line is built in landslide disease prone,which cost over 10 million yuan of the land-slide of 192,engineering management cost of about 4 billion yuan,serious impact on the normal construction of the highway.Based on this,the author on the basis of consulting thenbsp;192 landslide establish sample database,carries on the analysis to the high incidence of land-slide origin,in order to provide a reference for future similar to the red zone of highway safe-ty and economic construction. Research conclusions：（1）In water rich silty clay landslide accumulation body is project area landslide types and dominated by small to medium-sized landslide,landslide density, high cost of governance,which is the main characteristics of landslides in the area of the pro-ject.（2）The special geological environment of red bed region is a high incidence of landslide based,mainly reflected widely distributed on the surface of plastic to soft plastic like silty clay and the underlying water rich sand and shale formation of engineering disturbance sensi-tive,easy to make the slope after excavation and emban km ent fill loading,the rock and soil at the j unction surface and the maximum shear stress of surface accumulation layer landslide, flat push type and scattered type and crushed rock slope are formed in the near the level of occurrence of sandstone and mudstone in.（3）Under reasonable design of high incidence of landslides has a control function,mainly manifests in the geological line selection and imple-ment the poor,subgrade are relatively large size of the slope protection engineering targeted poor,resulting in a large number of engineering landslide,and treatment design cycle is too long,the landslide range continues to expand.（4）The construction side,heart is lack and unreasonable excavation and emban km ent is important factor for high incidence of land-slide.