作　　者： (欧阳涛坚）; (程春红）; (梁龙）;

机构地区： 浙江省工程勘察院,浙江宁波315012

出　　处： 《土工基础》 2017年第4期459-461,共3页

摘　　要： 浙东分布的砂砾岩,埋深较浅,胶结较差,钻探岩芯呈砂卵砾石散粒状,勘察易将其误认为砂砾石层或全风化基岩层,工程承载力取值往往偏低。结合该区部分工程勘察项目实践,就该区泥质弱胶结砂砾岩的特性及桩基承载力参数进行总结和分析。分析认为浙东地区弱胶结砂砾岩为软岩,岩芯碎散,胶结较差,但原岩强度较高。中等风化层,虽埋深较浅,承载力仍然较大,可以做为浅层基础持力层。对于荷载较大或变形要求较高的工程建筑(如超高层建筑)可采用后注浆或人工挖孔扩底桩等工艺。该地区施工工艺改进后,旋挖钻机成孔效率较高。 The conglomerate in east Zhejiang is generally shallow deposited and has weak cementation.The cored samples from the boreholes are usually in loose sand gravel shape.The geotechnical investigations are usually mis-classified as sandy gravelly layer or completely weathered bedrock.This weakly cemented bedrock is usually assumed to have excessively low bearing capacity.The geotechnical properties of the weakly cemented conglomerate rock layer are evaluated and the axial capacity of piles into the type of bedrock is also studied.The results indicate that this cemented conglomerate can be classified as a soft rock.Although the cored samples are loose and have low recovery,the original strength of the rock could be high.The bedrock is moderately weathered and can be served as load bearing layer of the shallow foundations without strengthening.For the heavily loaded structures or structures with high deformation requirements,the post construction grouting or manually excavated enlarged base caisson can be used.Further,the construction technique should be improved and the rotary drilling machine is a better technique.

关 键 词： 泥质弱胶结砂砾岩 动力触探 桩基承载力 桩基静载试验