探讨低围压条件下如何准确测试土体强度

On how to accurately testing compressive strength of soils under low confining pressure

准确测试土体的强度指标对地基基础的受力变形分析、稳定计算具有重要意义,对低围压(小于100 kPa)条件下的三轴试验而言,压力室传力杆的活塞摩阻、橡皮膜的径向约束不可忽视,同时设备的测试精度及量程也是应当考虑的重要影响因素。试图通过开展不同条件下的无侧限抗压强度试验、不同设备的三轴剪切试验等测试方案探讨活塞摩阻、橡皮膜等因素对测试结果的影响程度,探讨根据现有的测试条件如何测得试样的抗压及抗剪强度,为设计施工及数值计算提供可靠数据。针对国产三轴测试设备存在的不足提出了合理化建议,期望三轴测试设备从机械制造上进一步改造升级,推动中国精密三轴测试设备的研发。

It is important to study the stress deformation and stability of foundation by accurately testing the strength index of soils.For the triaxial tests under low confining pressures(less than 100 kPa),the influences of the piston friction and the rubber membrane can not be ignored.At the same time,the test accuracy and measuring range of equipments are also the important factors that should be considered.This study attempts to explore the influences of factors such as the piston friction and the rubber membrane on the test results by carrying out unconfined compressive strength tests under different conditions and triaxial consolidated undrained shear tests of different equipments,and to explore how to measure the compressive and shear strengths of samples according to the existing test conditions,so as to provide reliable data for design,construction and numerical calculation.In view of the shortcomings of domestic triaxial test equipments,reasonable suggestions are put forward,and it is expected that the triaxial test equipments should be further transformed and upgraded from mechanical manufacturing so as to promote the researches and development of precise triaxial test equipments in China.