分级加载下黏土中的超静孔压消散试验研究

Experimental Study on Dissipation of Excess Pore Water Pressure in Clay under the Stepped Time-dependent Loading

为直观地认识土体固结时超静孔压的消散过程,弄清固结理论产生偏差的原因,利用研制的大尺寸固结装置,对饱和黏土开展分级加载下的超静孔压、压缩变形和土压力的测试,并与太沙基一维固结理论计算值进行对比。测试结果表明土样中的超静孔压呈现加载后先增加、后消散缓降的规律,分级加载下,随着固结荷载增大,孔压变化明显滞后于荷载的变化,且超静孔压的消散也趋慢。经与采用固定固结系数计算的理论值对比可证实土样中的固结系数呈动态变化,表现为随固结荷载和固结时间的增加而减小,且不同位置处的固结系数也存在差异。

In order to understand intuitively the dissipating process of the excess pore pressure in the soil consolidation and clarify the reasons for the deviation of the consolidation theory,the saturated clay was consolidated under the stepped time-dependent loading by a large size consolidation device developed. Data include pore pressure,compression deformation and earth pressure were measured during soil consolidation. And the measured values of pore pressure were compared with the Terzaghi’s one-dimensional consolidation theory values. Test results show that the excess pore pressure in the soil sample increases first and then dissipates slowly after loading. With the increase of the consolidation load,the pore pressure changes obviously lag behind the change of the load,and the dissipation of the excess pore pressure is also slow. Compared with the theoretical values calculated by the fixed consolidation coefficient,the actual consolidation coefficient shows dynamic change,which decreases with the increase of consolidation load and consolidation time. And the consolidation coefficient at different locations is also different.