延吉膨胀岩变形特性的水-力路径效应与机制浅析

Effect and mechanism of hydro-mechanical path on deformation behavior of Yanji swelling rock

膨胀岩的体积变形受加荷模式和增湿过程的共同影响,为了研究不同水-力路径下延吉膨胀岩的变形特性,以延吉膨胀岩为研究对象,针对不同初始含水率的压实试样开展了3种水-力路径(1吸水膨胀(无荷)—加载压缩—卸荷回弹;2浸水吸湿(体积不变)—加载压缩—卸荷回弹;3加载压缩—浸水吸湿(有荷)—卸荷回弹)的一维压缩试验。试验结果表明:试样在路径1下的压缩指数和回弹指数最大,路径2下次之,路径3下最小,随着初始含水率的增加,试样在路径1和2下压缩指数和回弹指数逐渐减小,而在路径3下压缩指数逐渐增大;无荷状态下试样吸水膨胀,当上覆荷载较大时试样发生轻微的湿陷现象,无荷膨胀率和潜在湿陷率均随初始含水率的增加而减小;膨胀反压法和平衡加压法确定的膨胀力均随初始含水率的增加而减小,对于相同初始状态的试样,膨胀反压法确定的膨胀力较平衡加压法大;延吉膨胀岩的体变规律具有强烈的水-力路径效应,其强烈的水敏性是其中的根本原因。

The deformation of swelling rock is affected by both loading condition and moistening process. For the deformation behaviors of compacted swelling rock under 3 different hydro-mechanical paths ( ① soaking (with no load)-compression-decompression; ② soaking (with no swelling)-compression-decompression;compression③-soaking (under load)-decompression), laboratory tests on 1D compression of Yanji compacted swelling rock with different initial water contents are carried out. The test results show that the compression and swelling indexes of specimens under 3 different hydro-mechanical paths are not the same. The specimens under path ① provide the highest values of compressive index and swelling index, while the specimens under paths ③ provide the lowest. With the increase of the initial water content, the compressive and swelling indexes of specimens under paths ① and ② decrease, but the compressive indexes under path ③increase. The specimens swell obviously under no load condition, but they collapse slightly under a larger vertical load. The no-load expensive ratio and potential collapsible ratio decrease with the increase of the initial water content. The swelling pressures determined by the swelling and loading method and no-swelling method decrease with the increasing initial water content, and the values of swelling pressures provided by the former method are larger than those by the latter method. There is a clear effect of hydro-mechanical path on the deformation behavior of Yanji swelling rock, and the strong water sensitivity of swelling rock is the key factor.