兰州九州开发区不稳定斜坡勘查治理分析——以106队兰州基地东侧不稳定斜坡为例

Unstable Slope Investigation and Governing in Jiuzhou Development Zone,Lanzhou——A Case Study of an Unstable Slope at Eastside of No.106 Exploration Team Lanzhou Base

甘肃有色地勘局106队部东侧的不稳定斜坡位于兰州市九州开发区黄河北岸、罗锅沟左岸沟谷斜坡地带。勘查查明,不稳定斜坡中下部及坡脚地带为古近系砂质泥岩,斜坡中上部和坡顶为第四系全新统人工堆积物;其形成原因与地形地貌、地质构造、工程地质特征、降雨、地下水、人类工程活动等有关。根据定性分析和定量计算,认为勘查区斜坡现状处于不稳定状态,其失稳产生崩塌、滑坡的可能性大,最危险滑裂面位于填土和基岩的接触面;拟建工程建设遭受其危害的可能性及危险性中等。建议在治理斜坡时,坡脚挡土墙工程选用浅基础型式,跨越浅沟段(15m)可采用桩基础形式,以砂质泥岩作为基础持力层,并严格防止地表水渗入砂质泥岩地基。为区内不稳定斜坡的治理,防灾减灾提供了依据。

An unstable slope at eastside of the No. 106 Exploration Team, Gansu Bureau of Geology and Exploration for Nonferrous Metals is situated in the Jiuzhou Development Zone, north bank of Yellow River, left bank of Luoguogou ravine zone. Exploration has identified that the lithology of unstable slope lower part and slope toe is Paleogene sandy mudstone, while upper part and top of slope is Qua- ternary Holocene artificial deposits; the formation is related to landform and topography, geological structure, engineering geological features, rainfall and groundwater, as also human engineering activities. According to qualitative analysis and quantitative computation, considered that the status quo of the slope is under unstable state, collapse and landslide much more likely, most critical sliding surface is the interface between artificial fills and bedrock; hazard and risk of proposed engineering construction are medium. It is suggested that during the slope governing, slope retaining wall should use shallow foundation, groove spanning sector （15m） should use pile foun- dation, taking sandy mudstone as foundation bearing stratum, and strictly prevent surface water seep into sandy mudstone foundation. The study has provided the basis for unstable slope governing, hazard prevention and mitigation in the area.