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

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; ③ compression-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.