砂土介质中土压力盒的力学响应特性

砂土介质是典型的颗粒物质,介质的有效应力和变形都与骨架上的颗粒特性直接相关,而颗粒性状的改变进而影响着测试过程中土压力盒的力学响应。但宏观力学理论和连续介质方法无法准确解释介质颗粒间的力学行为,为了对实际工程进行更准确的测试,基于细观分析方法研究了荷载作用下的砂土颗粒接触形成的力链网络,模拟了力传递过程,并分析了加卸载时的力-应变曲线和土压力盒力学响应与理想曲线的关系,验证了文章提出的砂土介质土压力盒力学响应数值模型。同时,基于建立的颗粒流数值模型研究加载模式、颗粒排列、颗粒间摩擦系数以及压力盒刚度等对压力盒测试的影响,其结果显示压力盒力学响应曲线具有明显的迟滞性和应变不可逆性,其监测值对上述因素很敏感。因此,研究力链结构及其演变规律为认识砂土介质的细观结构提供了科学的理论依据和新的研究手段,各因素对压力盒力学特性的影响研究对压力盒标定和获得更准确的土压力值具有重要的实践价值。

Mechanical Response Characteristics of the Earth Pressure Cell in Sand

Sand is a typical particle structure.The effective stress and corresponding deformation are both determined by the particle characteristics of the medium skeleton,and the changeable condition of the particles will further affect the mechanical response of the earth pressure cell in the test process.To correctly measure the earth pressure value,micromechanical method was applied to analyse the force chain formed by the particles contact under loading-unloading condition,and the transferring process,the force-strain curve and relationship between the cell mechanical response and the ideal response curve were analyzed in detail,which verified the above mechanical response model based on Particle Flow Code（PFC） method.According to the structural characteristics of the sand and above numerical model,the loading condition,porosity,friction coefficient between the particles and stiffness of the earth pressure cell affecting mechanical response of the earth pressure cell were deeply investigated,the numerical results indicated that there were obvious hysteresis and strain irreversibility for the response curve,and the measured value was sensitive to the above factors.Therefore,research on the force chain structure and corresponding evolution law brings forward a scientific base and new research means for understanding its micromechanical characteristics,and different factors influencing the earth pressure cell are also important for cell calibration and practical monitoring to get more correct earth pressure value.