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通过新型低温动三轴仪的等幅循环荷载试验,以更为符合客观实际的围压、动应力幅值以及固结和冻结方式,研究了冻土冻结期的残余应变规律,包括了温度、荷载作用大小和次数对冻土的残余应变的影响。结果表明:冻土的残余应变随着荷载振动次数的增加不断增长,随着温度的降低不断减少;冻土的残余应变增长模式表现为开始阶段残余应变增长较快,后逐步缓慢增长,当动应力超过临界破坏应力之后,土试样残余应变迅速增长并达到破坏;低温冻土破坏应力较常温较大提高,低温-5℃提高了20%~25%,低温-10℃提高了45%~50%;冻土大多数荷载情况下处于非破坏状态,在一定次数荷载作用后,不同温度土的残余应变发展近似平行状态,大动应力幅值下的土试样的残余应变对温度更敏感。试验设计克服了以往试验过大固结应力和过大动应力的缺欠,得到的结果应符合客观实际。
Through the constant amplitude cyclic loading test of the new low temperature dynamic triaxial apparatus, the residual strain law of the frozen soil during freezing period was studied based on the confining pressure and dynamic stress amplitude that conform to the objective reality and the consolidation and freezing methods, including the temperature, Effect of load size and frequency on residual strain of frozen soil. The results show that the residual strain of frozen soil increases with the increase of load vibration frequency and decreases with the decrease of temperature. The residual strain of frozen soil shows a rapid increase of residual strain and a gradual increase of residual strain. After the stress exceeds the critical failure stress, the residual strain of the soil sample rapidly increases and reaches the destruction. The failure stress of the permafrost increases greatly compared with the normal temperature, the low temperature increases by 20% -25% at -5 ℃, and the low temperature-10 ℃ increases by 45% 50%. The frozen soil is in a non-destructive state under most of the loads. After a certain number of loadings, the residual strain in different temperature soils develops approximately parallel. The residual strain in the soil specimens under large dynamic stress is more sensitive to temperature . Experimental design to overcome the past test too large consolidation stress and excessive dynamic stress shortages, the results obtained should be consistent with the objective reality.