真三轴应力下塑性混凝土的强度和扩容

Strength and Dilatancy of Plastic Concrete in True Triaxial Tests

通过侧压恒定和侧向位移恒定的2类真三轴试验,研究了真三轴应力下塑性混凝土的强度和扩容.结果表明:在侧压恒定的真三轴试验下,塑性混凝土抗压强度随侧压的增加而增大,当第3主应力一定时,其抗压强度随第2主应力的增加而增大,体应变随轴压的增加呈现先增加后减小的特征,而体积则先减小后增大,出现扩容现象,当配合比相同时,其扩容的起始点随第2主应力的增加而增大;在侧向位移恒定的真三轴试验下,塑性混凝土的侧压随轴压的逐级增加而增大,抗压强度大幅度提高,可达单轴抗压强度的4.0～6.0倍,同时,其最终侧压与设定的初始值相比显著增大,且初始侧压越高,抗压强度越大,其最终侧压也越大,另外,其体应变随轴压的增加而增大,未出现扩容现象,而且初始侧压越高,体应变增加越大,体积压缩也越大.

Strength and dilatancy of plastic concrete were studied using two kinds of true triaxial compression tests, and lateral pressures were constant in one kind of test, and they increased with axial pressure in the other. The result shows that strength of plastic concrete increases with lateral pressure in the first kind of test, and when a3 is constant, σ1 increases with the increase of σ2. There is dilatancy for plastic concrete in the first kind of test; onset of dilatancy increases with the increase of σ2. Strength of plastic concrete increases greatly in the other test, to the extent of 4.0 - 6.0 times to that of the uniaxial compressive one. There is no dilatancy in the true triaxial compression test with constant lateral displacement; and volume of plastic concrete specimen decreases with the increase of axial pressure. Bulk strain increases with the increase of the initial lateral pressures.