Study On The Intensity Characteristic Of Xigeda Soft Rock Embankment Of Xichang-Panzhihua Express Highway

XiChang--PanZhihua area and XiChang--PanZhihua express highway were alongdistributed amount of Xigeda stratum. The stratum is nearly to semis-diagenetic stratum which is similar to soil or not, and similar to rock or not. It's not only poor in rigidity and intensity, but also is low in stability. Thus it became well-known for frequent geologic-disaster and landslide in the stratum area. Xigeda soft rock is made up from minute sandstone, mud siltstone, siltstone mud and mudstone. It is inland fluviolacustrine phase deposit rock with rhythm-cyclic character of depositional geology. Therefore, Xigeda filling material is a compounding filling made up of several soft rocks mentioned, which has more complex medium feature than single type filling material. We must certificate whether it satisfy minimum intensity standard of speedway's filling if the filling is used as roadbed material of express highway.By the large quantity of indoor and field soil mechanics test, this paper investigated physics and mechanics property of Xigeda stratum and Xigeda compounding filling, profoundly and systematically studied on shearing strength , CBR (including indoor CBR and field CBR) and intensity feature of Xigeda compounding filling. The new achievement and cognition as follows:(1) CBR value is decided by moisture content and mudstone content of Xigeda compounding filling. The filling material can satisfy minimum intensity standard of express highway when mudstone content is less than some fixed value,(2)This paper established field CBR standard value which can synthetically evaluate the filling material nature and field compaction degree.(3)The optimal compacting mean of Xigeda compounding filling is hard oscillation first and weak oscillation later, not traditional way which is weak oscillation first and hard oscillation later.(4)This paper put forward the conception of optimum moisture content in construction different from optimum moisture content of indoor impaction.Because CBR field test is simple and timesaving, therefore, Xigeda filling intensity (CBR) test which contain indoor and field test is economic and rational. Considering that the way to gain standard maximum dry density value of Xigeda filling is complex, this paper suggests adopt means combining field CBR test and compactness measuring to control construction quality.