小坪隧道膨胀岩地段的施工（Construction of swelling rock section of Xiao Ping tunnel）.doc

小坪隧道膨胀岩地段的施工（Construction of swelling rock section of Xiao Ping tunnel） Construction of swelling rock section of Xiao Ping tunnel A Li Yi [Abstract] treasure middle section of Baoan Xiao Ping tunnel, a part of the expansion of the rock strata containing. Because of the special engineering mechanics property of expansive rock, many tunneling problems have been caused. Leading to the collapse of the tunnel, increasing the difficulty of construction. In this paper, the characteristics of expansive rock and the construction measures are briefly analyzed. Expansion tunnel construction I. overview Small Ping tunnel length 2919m, tunnel crossing the watershed, steep mountains, the natural gradient of 30o ~70o maximum tunnel buried depth is about 130m. The hole body surface with 7 V shaped gully, the cutting depth is 40~50m, maximum 75~80m, Gouyan formed vertical scarp. The depth of the hole is intercalated with mudstone through the Cretaceous sandstone. The formation of the stratum is gentle and the dip angle is between 5ordm and ~10ordm. Mudstone is purple red, containing swelling minerals, coarse particles, thin - medium thick layer, muddy cementation, cementation is bad, soft, easy weathering. According to laboratory tests: mudstone mineral composition high in montmorillonite content 1.16~3.66%, illite content is 10.59~22.95%, the content of kaolinite clay content was 18~19%, less than 2 mu m occupies 14.5 ~ 27%, less than 5 m accounted for 23 to 42.5%, the expansion amount is 3.5 ~ 4.6%, the free expansion rate is 38 ~ 62%. The whole tunnel has 1400m, which is an expansive rock formation. In addition to the original design of tunnel entrance end of all kinds of import and export play a double game of 10 meters and Myongdong all using natmtry. Because they do not have started the construction of the new Austrian law, the import and export of 200m segment change design, modified by the next heading excavation, molded concrete lining construction. In August 1998, the cons