北海灰白色黏土工程地质特性及其成因分析

Engineering Geological Characteristics and Cause Analysis of Grayish-white Clay in Beihai

广西北海市某海域勘探深度40 m内广泛分布硬塑状含石英颗粒的灰白色黏土层,该土含水率低、密度大、比重小、孔隙比小,压缩性低,天然状态下剪切强度较高,渗透性极弱,存在吸水软化产生膨胀、失水收缩产生裂隙再浸水会迅速崩解至胶溶状的特性。选取49个钻孔200个灰白色黏土样品的室内物理力学试验结果进行数理统计分析,全面认识北海市灰白色黏土层的工程地质特性;通过XRD矿物成分分析、碳酸盐含量、土的腐蚀性、950°C高温烧失量等试验,结合广西地质资料和前人对北海黏土矿的研究成果,从土的形成演化、物质组成解释产生特殊工程性质的内在因素,对合理评价该类土的工程地质性质提供地质科学依据,为其开发利用和工程治理提供参考。

A very stiff grayish-white clay layer containing quartz particles is widely distributed within the depth of 40 m below seabed in Beihai,Guangxi.The soil has low water content,high density,small specific gravity,small void ratio,low compressibility,high shear strength in natural state,and very weak permeability.It has characteristics of swelling due to water absorption and softening,and cracks due to water loss and shrinkage,which will quickly disintegrate to the peptized state after immersion in water again.Mathematical statistical analysis was conducted on the indoor physical and mechanical test results of 200 grayish-white clay samples from 49 boreholes in the sea area.The engineering geological characteristics of the grayish-white clay layer in Beihai was comprehensively analyzed.XRD mineral composition analysis,carbonate content,soil corrosion,950℃ loss on ignition were carried out selectively.The internal factors are evaluated combined with Guangxi geological data and previous research results on Beihai clay,from the formation of soil and material composition,which provide a scientific basis for the rational evaluation of the engineering geological properties of this type of soil,and also provide reference for its development,utilization and engineering management.