复杂环境下基于CPTU的深基坑土压力模型与工程应用  

A CPTU-based earth pressure model for deep excavations under complex environment and its practical application

作　　者：刘松玉[1,2] 赖丰文 蔡国军 李洪江 鲁泰山[1] 张超哲 LIU Songyu;LAI Fengwen;CAI Guojun;LI Hongjiang;LU Taishan;ZHANG Chaozhe(Institute of Geotechnical Engineering,Southeast University,Nanjing 210096,China;Nanjing Modern Multimodal Transportation Laboratory,Nanjing 211100,China;School of Civil Engineering,Fuzhou University,Fuzhou 350116,China;School of Civil Engineering,Anhui Jianzhu University,Hefei 230601,China)

机构地区：[1]东南大学岩土工程研究所,江苏南京211189 [2]南京现代综合交通实验室,江苏南京211100 [3]福州大学土木工程学院,福建福州350116 [4]安徽建筑大学土木工程学院,安徽合肥230601

出　　处：《岩土工程学报》2024年第8期1563-1572,共10页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(41972269)。

摘　　要：土压力计算是深基坑围护结构设计的重要组成部分,但现有土压力模型难以合理地考虑开挖扰动诱发土体工程性质演化影响。孔压静力触探(piezocone penetration test,CPTU)能够有效避免取样扰动,并快速提供连续的原位土测试参数(锥尖阻力、侧壁摩阻力、孔隙水压力)。基于CPTU原位测试和位移相关土压力模型,结合库仑土压力框架,综合考虑开挖诱发土体工程性质演化、邻近地下结构(受限空间)、土拱效应、地基土强度参数和土-结构界面摩擦角等影响因素,构建了复杂环境下深基坑土压力统一计算模型(主动状态至被动状态)。分别通过与室内1g模型试验和离心机试验结果对比,验证了所构建模型的准确性与合理性。进一步将所构建模型应用至太湖冲湖积相软土地区某邻近地铁车站的深基坑工程。现场分别在基坑开挖前后对围护结构的两侧(基坑内外)开展了CPTU原位测试,并监测得到了围护结构侧向变形与土压力变化。原位测试解译结果表明,基坑开挖显著地改变了周边土体状态参数,但对于有效内摩擦角的影响甚微。与现场所测土压力对比指出,基于CPTU的土压力模型能够较好地反映复杂环境下基坑土压力变化,成功实现了工程应用。The determination of earth pressure is a key element for the design of retaining structures of deep excavations.However,the existing earth pressure models can not reasonably consider the change of soil properties induced by excavation activities.The piezocone penetration test(CPTU)is capable of effectively avoiding the sampling disturbance and quickly providing the continuous in-situ testing parameters of soils(cone resistance,sleeve friction,pore water pressure).Combining the CPTU tests and the displacement-based earth pressure model,the change of soil properties induced by excavations,surrounding buried structures(confined soil),soil arching effects,soil strength parameters and friction angle of the soil-structure interface are comprehensively taken into account to develop a unified earth pressure model(from active-to passive-state)under the Coulomb’s earth pressure framework.The comparisons of earth pressures obtained between 1g-/ng-model tests and the developed model are made for the validation.Subsequently,the developed model is employed in a deep excavation adjacent to a metro station in soft soils deposited in the Taihu Lake.The CPTU tests are then performed in the soils around both sides of retaining structures,of which the earth pressure and lateral deformation are also measured.The interpretation of in-situ testing results indicates that state parameters of soils significantly change due to excavations,but the effective friction angle almost remains unchanged.The further comparisons of earth pressures obtained between the measurement and the developed model indicate that the CPTU-based earth pressure model works well for a deep excavation under a complex environment,thus successfully reaching a practical application.

关 键 词：孔压静力触探(CPTU) 原位土力学 开挖扰动 受限空间 位移相关土压力 

分 类 号：TU432[建筑科学—岩土工程]