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研究结果表明:①型砂在静态压力作用下,有侧限情况下的应力-应变(σ-ε)关系曲线分为三个阶段,即退让阶段、紧实阶段和应变截止阶段。②膨润土含量主要影响σ-ε曲线的第二、三阶段,膨润土含量越大,型砂在紧实过程中吸收的应变能越大,从而得到的砂型强度也大。③紧实率对σ-ε关系的影响主要在退让阶段,紧实率愈大,退让阶段愈长。应力与紧实度(硬度与强度)之间具有对应关系。④型砂和砂箱内壁之间的摩擦系数为0.5,摩擦角约为27°。
The results show that: (1) The stress-strain (σ-ε) curve of sand under static pressure is divided into three stages, that is, concession phase, compaction phase and strain cut-off phase. ② The content of bentonite mainly affects the σ-ε curve in the second and third stages. The larger the bentonite content is, the larger the strain energy absorbed by the sand during compaction is and the stronger the resulting sand is. ③ The effect of compaction rate on the relationship between σ-ε is mainly in the concession phase, the greater the compaction rate, the longer the concession phase. There is a correspondence between stress and firmness (hardness and strength). ④ sand and sand box wall friction coefficient of 0.5, the friction angle of about 27 °.