寒区高速铁路路基粗颗粒填料大型直剪试验研究

摘要

为研究寒区高铁路基粗颗粒填料直剪特性，本文进行高压实度状态下级配碎石和A组土在不同垂直压力、含水率和温度条件下的直剪试验。由于粗料含量影响，试验中的粗颗粒填料抗剪强度主要决定于粗料、细料之间的共同作用。粗颗粒土冻结强度由土中已冻结孔隙冰、颗粒间的黏聚力和咬合力、粗细颗粒本身强度共同贡献。试验结果表明：非冻结和冻结状态下的粗颗粒土剪切应力‐剪切位移曲线从应变软化逐渐向应变硬化过渡；试样垂直压力、冻前含水率和温度明显影响粗颗粒填料的抗剪强度及其指标。垂直压力增大，粗颗粒土抗剪强度明显提高。在冻结状态下，随着含水率增大、温度降低，粗颗粒土抗剪强度和 C值逐渐增大，内摩擦角变小。由于细颗粒和粗颗粒间的共同作用更强，与A组土相比，级配碎石在冻结和非冻结状态下抗剪强度及其指标有相似的变化规律，但有更大的 C值和内摩擦角。%In order to study the direct shear behaviors of coarse‐grained fillings taken from subgrade of high‐speed railway in cold region , direct shear experiments were conducted on graded gravel and Group A soil with high degree of compaction under different normal stresses ,water contents and temperature conditions .Due to the influence of coarse particle content , the shear strength of these fillings was mainly determined by the inter‐action between coarse particles and fine particles . The freezing strength of the coarse‐grained fillings depended on the freezing strength of pore ice , the cohesion force and interlocking force between fine‐grained and coarse‐grained particles ,as well as the strength of fine and coarse particles . The experiment results indicated that the shear displacement versus shear stress curves changed from strain‐softening with lower normal pressure to strain‐hardening with higher normal pressure , under both unfrozen state and frozen state . The normal pres‐sure , water content and temperature of the test specimens significantly affected the shear strength and indexes of coarse‐grained fillings . The shear strength of the coarse‐grained fillings increased with the increasing of nor‐mal pressure . With temperature decreasing and water content increasing under the frozen state , the shear strength and value C of frozen coarse‐grained fillings increased gradually w hile the internal friction angle de‐creased .Because of the greater interaction between the particles , the graded gravel showed similar changes in terms of shear strength and indexes but had greater value C and internal friction angle than Group A soil under the unfrozen state and frozen state .