甘肃定西公路建设中的工程地质问题分析

Engineering geological problems of highway construction in Dingxi City,Gansu Province

定西市处于祁—吕—贺兰山字型构造与河西构造两大地质构造体系的复合部位,滑坡、崩塌、泥石流等地质灾害与不良地质发育。依据地质调查、新建公路的规划勘察等资料,系统分析气象水文、地形地貌、地质构造与公路建设中的若干工程地质问题。分析发现:特殊的地理位置和地质环境决定了不同的气象水文与地貌类型。按气候特征将定西地区划分为渭河以北的黄土丘陵沟壑区和以南的高寒阴湿区,前者频繁发生滑坡、崩塌、黄土陷穴等地质问题,后者主要发生泥石流,同时广泛分布滑坡、崩塌等,湿陷性黄土、疏松砂岩、软岩破碎与大变形等特殊岩土与不良地质问题影响严重制约着公路走廊带选择、路线方案的地质安全和构筑物布置与施工。针对上述公路沿线的工程地质问题,深入探讨工程地质问题的分布规律与发育特征,并给出了调查分析与防治措施,为区域内工程施工与防灾减灾提供依据与理论支撑。

Dingxi City,Gansu Province,situated at the intersection of two tectonic systems,namely,the Qi—Lü—Helan tectonic system and the Hexi tectonic system,is susceptible to geological hazards such as landslides,collapse,and debris flow.To reduce these risks,systematic analysis of meteorology and hydrology,topography,geological structure,and various geological problems associated with highway construction was performed by using geological survey data and planning and survey data of existing and new roads.The analysis results revealed a close link between the diverse meteorological,hydrological,and geomorphological phenomena in the region and its unique geographic location and geological environment.The Dingxi area is categorized based on climate characteristics into a hilly-gully loess plateau in the north of the Weihe River and a high-cold and humid region to the south.The former is susceptible to geological problems such as landslides,collapses,and loess sinkholes,while the latter is prone to debris flows and widespread occurrence of landslides and collapses.Furthermore,special rock and soil properties,such as collapsible loess,soft rock fragmentation and severe deformation,loose sandstone,and other adverse geological conditions,considerably hampered the geological safety of road alternatives,the selection of a highway corridor,and the layout and construction of structures.This work offers a detailed discussion of the distribution law and development characteristics of these geological problems along the highway,as well as proposes comprehensive investigation and prevention measures to provide sound foundation and theoretical support for engineering construction and disaster prevention and mitigation in the region.