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通过室内试验和原位静载荷试验对工程经验和试验研究资料欠缺的北京市密云县浅山区薄层黄土的湿陷性特征进行了研究。根据室内试验成果,总结分析了研究区黄土物理指标与湿陷系数的关系。湿陷性终止含水量介于25%~30%;湿陷变形经历压密、稳定、破坏三个阶段;较小(50kPa)压力下黄土的湿陷敏感性弱,随着压力的增大敏感性增强,至100~150kPa时,敏感性达到峰值,随后逐渐减弱。选取研究区典型粉土层和粘土层进行了天然状态和浸水饱和后的原位静载荷试验,分析P-s曲线和s-lgt曲线认为,粉土层浸水饱和后的压缩变形经历四个阶段,湿陷性强烈,湿陷等级为II级,湿陷起始压力为50kPa;粘土层不湿陷,浸水饱和后应变硬化在0~25kPa阶段完成,此后沉降量基本随压力的增大呈线性增长,没有出现像粉土层浸水后在压力作用下结构性反复破坏的现象。
The collapsible characteristics of thin-layer loess in shallow mountain area of Miyun County, Beijing, which are lack of engineering experience and experimental data, were studied by laboratory tests and in-situ static load tests. According to the laboratory test results, the relationship between the physical indexes of loess and collapsibility coefficient is analyzed and summarized. The water content of the collapsed ends is between 25% and 30%. The deformation of the collapsible reservoir undergoes three stages of compaction, stabilization and destruction. The wettability of the loess under the smaller (50kPa) pressure is weak and sensitive to the pressure increase Sex enhancement, to 100 ~ 150kPa, the sensitivity peaked, then gradually weakened. Select the study area of the typical silt layer and clay layer in situ state and saturated water saturation load test in situ, analysis of Ps curve and s-lgt curve that the water-saturated soil after compression deformation undergoes four stages, wet The collapse level is Grade II, the initial collapse pressure is 50kPa; the clay layer is not collapsed, and the strain hardening after saturated water saturation is completed in 0 ~ 25kPa stage. The settlement then increases linearly with the increase of pressure, There is no structural damage caused by pressure under the influence of silt layer soaking.