| A lot of weathered Metamorphic soft rocks such as tunnel spoil and cut slope spoil would be generated in Qinling Mountain free way construction. If these weathered metamorphic soft rocks were used as embankment filler, which not only would reduce construction investment costs, and also would protect the local fragile ecological environment, with significant social and economic benefits. However, the weathered metamorphic soft rocks with low intensity, easily weathered, poor water stability characteristics, which can be used as embankment filler and how to be used become a serious problem. In response to the problem, on the basis of investigating, analyzing and summarizing the previous research achievements, this article depending on the Zha-xiao free way systematically and deeply studied on application of soft weathered metamorphic rock in Qin-ling mountains as free way embankment filler by means of laboratory and field experiments, the conclusions are listed as follows:1. According to the results of strength tests of rock, the effects of the weathering degree to division of soft and hard rock are discussed. The weathering two-mica schist mylonite and mylonitic phyllite was identified as soft metamorphic rock, and the feasibility of the weathered metamorphic soft rocks as embankment filler was initially evaluated by means of the rock mineral analysis test, collapse test, swelling test.2. The grain composition of weathered metamorphic soft rocks as embankment filler was definite by means of mathematical statistics method, and the characteristics such as grain composition, density, CBR, compression deformation, compressive creep, strength and particle breakage was discussed, especially the effect of the occurrence of water was disclosed.3. The screening test on the grain composition was carried out after the vibration compaction test, compression test and triaxial shear test, to analyze in detail the effects of the super-size treatment method, soaking time, the vibration frequency and cycle numbers to particle crushing of soft weathered metamorphic rock filler, and to compare particle breakage in the process of three trials, and to point out the particle breakage under the action of vibration compaction should not be ignored the reason that the stress state is different between embankment and dam filler, and the weathered metamorphic filler particles in the low stress state was easy to produce a mass of particle breakage.4. The optimal technological parameters and quality control specification applied to the weathered metamorphic soft rocks as embankment filler were propose through field filling and compaction tests, which including loose laying depth, rolling compaction times and sprinkling.5. In order to better reflect the immersion settlement of soft weathered metamorphic rock embankment, the indoor large-scale test embankment (long6m, bottom width6m, top width4m, high1.6m) was built in the Asian largest slot (length100m, width7.5m, high2.8m) for the first time. Through the soaking load test of the embankment, the conclusion that the soaking settlement deformation of9.6m high embankment was more than6.12cm. According to the above result, the soft weathered metamorphic rock was successfully used as embankment filler in Zha-xiao free way, and to save the cost of the project about65million yuan, and to protect the local fragile ecological environment, and to make significant social and economic benefits. The result was found that the post construction settlement deformation of soft weathered metamorphic rock embankment is smaller and it’s operation is good. |
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