为了研究土样含水率等因素对黏土侧压力系数K0的影响,自行研制可考虑土体浸湿过程的实验仪器,采用气缸对试样施加竖向荷载,并在侧壁环上粘贴电阻应变片测定试验过程中试样的侧向应力.在洞庭湖区汉寿仓儿总大桥桥台处地表以下2m处取工程土样进行分析.在试验过程中,采用蠕动泵对仪器底座通水,使试样在较小流量作用下均匀浸湿,模拟实际工程中的浸湿条件,分别测试试样的竖向应力、竖向应变、侧向压力等随时间的变化规律,以此为基础对试样的应力状态、应力路径、K0在试验过程中的变化规律及其与试样干密度之间的关系进行分析.研究结果表明:干燥湖区地表硬壳层黏土K0随密度的增大而减小,由初始的0.40减小至0.21,但其减小的速度随密度的增大而有所减缓；在竖向恒定荷载σ1=655 kPa作用下,完全干燥的湖区地表硬壳层黏土在浸湿后会发生较大竖向变形,且K0从0.21逐渐减小,最后趋于稳定值0.16.%In order to study the effect of factors such as water content on the coefficient of lateral earth pressure at rest K0 of clay, the test apparatus taken into account wetting process of sample was designed, in which samples were vertically loaded by cylinder, and the lateral earth pressure was measured by strain gauges glued at three levels on the side ring. Undisturbed soil sample was gotten at 2 m below the ground around abutment of Cangerzong bridge in Hanshou county in Dongting Lake district. In the test, the relationship among vertical stress, vertical strain, lateral earth pressure and time were studied, and stress condition, stress path and behavior of K0 were analyzed. The results show that K0 of totally dry clay decreases from 0.40 to 0.21 with the increase of dry density of sample, and the larger the density, the lower the rate of decrease of K0. When the constant vertically load σ1 is 655 kPa, a large settlement in the sample occurs in wetting processs, and K0 finally decreases to 0.16.
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