基于透明土的成层土中CPT贯入试验研究  

Experimental study on CPT penetration in layered soil based on transparent soil

作　　者：卢谅[1,2] 何兵 肖亮 王宗建 马书文[1,2] 林浩鑫 LU Liang;HE Bing;XIAO Liang;WANG Zong-jian;MA Shu-wen;LIN Hao-xin(School of Civil Engineering,Chongqing University,Chongqing 400045,China;Key Laboratory of New Technology for Construction of Cities in Mountain Area,Ministry of Education,Chongqing University,Chongqing 400045,China;College of River&Ocean Engineering,Chongqing Jiaotong University,Chongqing 400074,China)

机构地区：[1]重庆大学土木工程学院,重庆400045 [2]重庆大学山地城镇建设与新技术教育部重点实验室,重庆400045 [3]重庆交通大学河海学院,重庆400074

出　　处：《岩土工程学报》2022年第12期2215-2224,I0026,共11页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金面上项目(52178314)。

摘　　要：静力触探(CPT)在成层土中的贯入阻力受土层界面影响显著,但目前对探头穿越土层界面时出现的“超前、滞后”现象仍缺乏系统的解释,利用贯入阻力划分土层仍依靠工程经验。采用透明土模型试验模拟探头在成层土中的贯入过程,通过观测探头阻力变化曲线和探头附近土体的变形情况,研究CPT在成层土中的贯入机理。结合扩孔理论和Mohr-Coulomb准则,提出锥尖阻力影响深度的计算方法,结合试验数据和理论计算,得到上层砂土下层黏土的塑性区影响范围与贯入阻力曲线的“超前”深度一致。并利用PFC分析成层土中,CPT贯入阻力反映的层间界面效应的影响因素。结果表明,CPT贯入过程中土体变形与土体自身强度、初始地应力和土层界面位置有关;相邻两层土体的强度差异对“超前、滞后”深度有显著影响。利用本文结论根据土体的塑性区影响范围与土体的超前深度一致对土层进行划分,对比目前的土层划分的复杂性,可直接依据该方法对土层直接划分,提高了土层划分的效率和准确性。The penetration resistance of cone penetration test(CPT)in layered soil is significantly affected by the soil interface,but there is still a lack of systematic explanation for the phenomenon of"leading and lagging"when the probe crosses the soil interface.The division of soil layers through the penetration resistance still depends on engineering experience.A series of transparent soil model tests are carried out to simulate the penetration process of the probe in layered soil.The penetration mechanism of CPT in the layered soil is studied by observing the resistance curve of the probe and the deformation of soil near the probe.Combining with the cavity expansion theory and the Mohr Coulomb criterion,the method for calculating the influence depth of the cone resistance is proposed.Based on the test data and theoretical calculation,it is found that the influence range of the plastic zone in the two-layered soil with the upper sand and the lower clay is consistent with the"leading"depth of the penetration resistance curve.PFC is used to analyze the influence factors of the interface effct reflected by the CPT penetration resistance in layered soil.The results show that the soil deformation during CPT penetration is related to the soil strength,the initial in-situ stress and the position of soil interface.The strength difference between two adjacent layers of soil has a significant influence on the"leading and lagging"depth.Based on the research results,the soil layer is divided according to the plastic zone of soil and the leading depth of soil.Compared with the current complex methods of soil layer division,the proposed method can improve the efficiency and accuracy of soil layer division.

关 键 词：透明土 静力触探 扩孔理论 离散元模拟 

分 类 号：TU43[建筑科学—岩土工程]