基于CPTU原位测试的软弱土岩土参数敏感性辨识与应用研究

The geological environment in soft soil area has some special geological features, fragile sensitivities and site-dependence geographic differences, which often cause many major geotechnical accidents. To characterize the soft soil parameters sensibility, the drilling and laboratory test are not enough. In order to cooperate on the insufficiency and unreliable parameters for the construction in soft soil area, there are urgent needs to develop the advanced in situ testing. The piezocone penetration testing (CPTU) is a new in situ testing technique arisen in international country these years, which can evaluate the geotechnical engineering characteristics and parameters sensibility of soft soil precisely and quantitatively. In this research, the soil parameters sensibility will be assessed based on the theoretical analysis, numerical simulation, laboratory test and in situ testing. The multivariate variable correlation models of soft soil parameters will be developed based on the in situ testing CPTU. The failure mode of the foundation pit will be revealed based on the characteristic of parameters sensibility of soft soil from CPTU data. Based on the random finite element theory, the foundation pit robust geotechnical design method will be proposed from characteristic of parameters sensibility in the soft soil. It is believed that the research results have the important theoretical and practical significance for enhancing the level of in situ testing for soft soil and establishing the reliability design method of geotechnical engineering practice in China.

软弱土地区的地质环境有着特殊的地质特征、脆弱敏感性和地域差异性，常常造成许多重大岩土工程事故。要定量表征软弱土复杂介质及其参数的敏感性，仅靠钻孔及室内试验资料是不够的，需要发展先进的现场原位测试技术，以解决软弱土工程建设中常常出现的设计所需参数不全、不可靠的问题。现代数字式多功能孔压静力触探（CPTU）是近年来在国际上兴起的新型原位测试技术，可以准确评价软弱土工程特性及其参数敏感性特征。本项目采用理论分析、数值模拟、室内试验与原位测试相结合的方法，研究基于CPTU测试的软弱土岩土参数敏感性特征；建立基于CPTU测试的软弱土岩土参数多元变量相关性模型；揭示基于参数敏感性特征的软弱土基坑失效模式；基于随机有限元理论，总结建立基于参数敏感性特征的软弱土基坑稳健性理论与设计方法。研究成果对提高我国软弱土原位测试水平、建立符合岩土工程实践的可靠度设计方法具有重要的理论与和实践指导意义。

随着国民经济高速发展，我国的城市建设发展异常迅速，相关的地下工程越来越多，特别是沿海地区城市，大部分深基坑工程位于软土中，对基坑工程的安全性提出了更高的要求。软弱土地区的地质环境有着特殊的地质特征、脆弱敏感性和地域差异性。本项目基于现代数字式多功能孔压静力触探（CPTU）测试技术，联合理论分析、数值模拟、室内试验，通过CPTU测试的软弱土岩土参数敏感性特征，建立基于CPTU测试的软弱土岩土参数多元变量相关性模型，以揭示基于参数敏感性特征的软弱土基坑失效模式。采用蒙特卡洛模拟，分析不排水抗剪强度的空间变异性对软土基坑（抗隆起和抗倾覆）可靠性影响。考虑土体参数的敏感性，优化设计方案的系统功能响应变化和成本造价，获得内撑式地下连续的软土基坑稳健性设计结果。研究成果对提高我国软弱土原位测试水平、建立符合岩土工程实践的可靠度设计方法具有重要的理论与和实践指导意义。