红层泥岩改良土特性室内试验研究

宜巴高速公路穿越巴东组紫红色泥岩地层。直接将泥岩风化物作为路基填料填筑，产生了路面鼓包，翻浆冒泥和路基不均匀沉降、承载力不足等工程问题。为了消除泥岩路基土不良特性，采用石灰、水泥、粉煤灰对泥岩风化物进行改良试验研究。开展击实、承载比、无侧限抗压强度试验，利用自制崩解仪、大环刀进行改良土崩解试验及土水特性测试，利用环境电镜扫描改良土微观结构，研究分析泥岩改良土的工程特性及改良机制。在综合评价改良效果及分析膨胀指标、承载比、无侧限抗压强度等常规改良效果评价指标基础上，尝试结合耐崩解性、土水特性指标全面对比分析改良效果。结果表明：改良剂消除泥岩路基土的膨胀特性，大幅提高其承载力及抗压强度指标，其耐崩解性及水稳定性也得到提高和改善；水泥改良路基土效果最佳，掺比5%为最优；石灰改良效果次之，最佳掺比为7%；粉煤灰改良效果最差，掺比11%为最优，适当提高粉煤灰掺量改良效果会更佳。

INDOOR EXPERIMENTAL RESEARCH ON CHARACTERISTICS OF IMPROVED RED-MUDSTONE

The purplish-red mudstone of the Badong group appears in large numbers in the highway from Yichang to Badong. When the weathering mudstone was used as the fillings of highway embankment，lots of engineering problems appeared，such as road bulges，shoulder of road gushing，the uneven settlement and the lower bearing capacity. In order to eliminate the undesirable properties of embankment soil，a modified experiment was conducted with lime，cement，fly ash. The compaction test，California bearing ratio(CBR) test，unconfined compression test，disintegration test by using self-made disintegration instrument and soil-water test were conducted to study the characteristics of improved soil. The microstructure of improved soil was scanned by environmental electron microscope. When the improvement effect was evaluated；the basic indices such as bearing ratio，unconfined compressive strength，expansion index were not only considered but the index of soil-water characteristics and resistance of disintegration were also tried to be analyzed. The results show that the expansion characteristics of purplish-red mudstone is eliminated by modified materials. The bearing capacity of the subgrade soil and unconfined compression strength are vastly improved. The characteristics of water stability and resistance of disintegration are also improved. The improvement effect of the improved soil mixed with cement is the best，the best cement proportioning is 5%. The improvement effect of improved soil mixed with lime is the better and the best mixing ratio of lime is 7%. The improvement effect of fly ash soil is the worst and the best mixing ratio of fly ash content is 11%. To increase the fly ash content may make the improved effect to be better.