成都市中心城区膨胀土工程地质特征分区

Zoning of Expansive Soil Based on Its Engineering Geological Characteristics in Central Urban Area in Chengdu

以成都市中心城区膨胀土为研究对象,在全面搜集已有勘察资料基础上,结合现场调查及室内外试验,全面刻画了成都市域内膨胀土空间展布特征,对其结构特征、物理力学特征、胀缩性和裂隙性进行了系统总结,在此基础上对膨胀土进行了分区.研究表明,成都市膨胀土由西向东逐渐增厚,厚度2.64~24.1 m,平均厚度10.8 m;纵向可划分为3层,其中Ⅲ层裂隙极发育,团块状灰白色黏土增多,局部为灰白色黏土;隙壁灰白色黏土比灰黄色黏土层黏土矿物含量高、含水率高、膨胀性强,其与裂隙的存在劣化了土体力学性质;灰黄色黏土具有弱膨胀潜势,黄红色黏土具有弱—中等膨胀潜势,根据土体膨胀特性,将成都划分为弱膨胀区、出露型弱—中膨胀区和埋藏型弱—中膨胀区3个大区.

By taking expansive soil in Chengdu as the research target,based on the comprehensive collection of survey data in Chengdu,and by means of field investigation and test in laboratory and field,the spatial distribution characteristics of the the expansive oil in the urban in Chengdu is depicted,and the structure characteristics,physical and mechanical charactevistics especially the swell-shrink characteristics and the fracture charctensics are systematifcally summarized.Based on what has been mentioned above,the expansive soil is divided into different zones.The studies show that the thickness of expansive soil increases from west to east gradually.Meanwhile the thickness of such oil in Chengdu is 2.64~24.1 m,with an average thickness of 10.8 m.Vertically,it can be divided into three layers,among which the fractures of layer III are extremely developed,the number of massive gray white clay increases,and the gray white clay is locally distributed.The fissure wall clay has higher mineral content,higher water content and higher expansibility than the yellow clay,and the existence of fissures worsens the mechanical properties of the soil;the gray yellow clay has weak expansion potential,and the yellow red clay has weak-medium expansion potential.According to the expansion characteristics of the soil,Chengdu is divided into three regions:weak expansion zone,exposed weak medium expansion zone and buried weak medium expansion zone.