深基坑模型试验中相似土配比及其微观表征研究

Mixture ratio of similar soil for deep foundation pit model test and its microscopic characterization

相似地质模型试验是深基坑等岩土工程研究中的一种重要方法,但关于岩土体相似材料的选取、制备工艺及试验适用性等方面的研究仍存在着诸多不足。依托南通地铁1号线汽车东站某基坑工程,在了解该地区富水砂层地质条件的基础上,根据土质相似材料配制要求,选取粉细砂、重晶石粉、洗衣液、膨润土、水为原料,基于正交试验方法进行配比研究,测得不同配比条件下相似土的物理力学参数并对其开展敏感性因素分析。此外,从微观角度进一步分析了各因素对相似土性质的影响机理及其微观结构特征。结果表明:相似土密度受重晶石含量控制,呈正相关关系;黏聚力受含水率与洗骨比控制,呈负相关;内摩擦角与各因素皆呈负相关,受重晶石含量控制;压缩模量与除含水率外的3因素均呈负相关。试验中不同配比相似土的物理力学性质参数分布范围较广,可为类似模型试验中土质相似材料的配制提供参考。

Similar geological model test is an important method for geotechnical engineering research such as deep foundation pits.However,there are still many deficiencies in the research on the selection of similar materials,preparation technology and test applicability.In this paper,taking a foundation pit project of the East Bus Station of Nantong Metro Line 1 as the research object,on the basis of understanding the geological conditions of the water-rich sand layer in the area,according to the development requirements of soil similar materials,fine sand,barite powder,laundry detergent,bentonite and water were selected as the raw materials.Based on the orthogonal test method,the physical and mechanical parameters of similar soil under different mixture ratio conditions were measured,and the sensitivity factors were analyzed.In addition,the influence mechanism of various factors on the properties of similar soil and its micro-structure characterization were further analyzed.The results showed that the density of similar soil was controlled by the barite content and the two were in positive correlation.Cohesion was controlled by water content and bone washing ratio,which showed a negatively correlation.The internal friction angle was negatively correlated with all factors and was controlled by barite content.The compression modulus was negatively correlated with the three factors except water content.The physical and mechanical parameters of similar soils with different mix ratios were widely distributed in the test,which can provide a reference for similar model tests.