温度效应对钙质砂体积应变和固结特性的影响

为了探究温度变化引起钙质砂体积应变的作用机制，在不同温度和围压下对南海钙质砂进行温控三轴试验，并与石英砂试验进行对比. 研究表明：升温引起相对密实度为70%的钙质砂和石英砂产生压缩体积应变；升温引起的钙质砂热体积应变远大于石英砂，且钙质砂热体积应变对围压的敏感性远强于石英砂；在围压较大时，升温引起的钙质砂热体积应变明显增加且体积应变发展模式显著改变. 利用温控固结仪研究不同温度下钙质砂和石英砂的固结特性. 研究表明：随温度升高，2种砂在e-lg p面内的压缩曲线先向上移再下移，直线段的斜率先减小后增大，但达到固结稳定的时间均提前；不同于石英砂，在45~75°C下，升温导致钙质砂的固结压缩量显著增加，远超常温水平，这是因为由筛分试验发现，随温度增加，钙质砂颗粒破碎程度增大，导致其在高温固结时的压缩量增大.

Effect of temperature on volume strain and consolidation characteristics of calcareous sand

A series of temperature-controlled triaxial tests were conducted on calcareous sand from the South China Sea under different temperatures and confining pressures, in order to explore the mechanism of effect of temperature change on the volume strain of calcareous sand. Results show that the increase of temperature will cause compressive volume strain of calcareous sand and quartz sand with relative density of 70%. The thermal volume strain of calcareous sand caused by temperature rising is much larger than that of quartz sand, and the sensitivity of thermal volume strain of calcareous sand to confining pressure is much greater than that of quartz sand. When the confining pressure is high, the thermal volume strain of calcareous sand caused by temperature rising increases significantly and the development mode of volume strain changes obviously. The consolidation characteristics of calcareous sand and quartz sand under different temperatures were studied by using temperature-controlled consolidation apparatus. Results show that with the increase of temperature, the compression curves of two kinds of sand in e-lg p plane move upward and then downward, and the slope of straight section decreases first and then increases, but the consolidation stability time of two kinds of sand is ahead of time. Comparing with quartz sand, the consolidation compression of calcareous sand increases significantly in the temperature range of 45~75 °C, which is much higher than that of calcareous sand at normal temperature. Screening tests show that with the increase of temperature, the degree of particle breakage of calcareous sand after consolidation increases significantly, which leads to the increase of compression of calcareous sand during high temperature consolidation.