掺水泥粉土的改良风积沙三轴压缩特性

基于单掺5%水泥的经济性设计指标，开展了混掺水泥粉土的改良风积沙三轴压缩试验，分析了改良风积沙试样不同围压下的应力-应变及强度特性，揭示了不同掺比改良风积沙黏聚力和内摩擦角的变化规律，以及改良风积沙的破坏形式及剪切破坏机理。结果表明：改良风积沙的应力-应变关系曲线均为应变软化型曲线；弹性模量和破坏强度与围压正相关，弹性模量在粉土掺量增至15%时达到峰值；破坏强度与粉土掺量正相关；10%粉土掺量下改良风积沙黏聚力最大，内摩擦角则随粉土掺量增加而单调增长。水泥水化物包裹在沙粒表面，增加了沙粒表面粗糙度，并在沙粒之间的空隙形成网状结构，将沙粒联结起来，阻碍沙粒相对运动；掺入适量粉土可填充沙粒和水化物之间的空隙，但过量粉土会制约水化反应，同时碱性离子与水化物反应产生胶结能力差的硅酸钠和铝酸钠，导致改良风积沙整体性能下降。

Study on triaxial compression characteristics of improved aeolian sand mixed with cement silt

Based on the economic design index of single 5% cement, the triaxial test of improved aeolian sand static in mixed cement silt was carried out.The stress-strain and strength characteristics of improved aeolian sand sample under different confining pressures were analyzed, based on which the change law of the viscosity and internal friction angle of different doping ratios, the failure form of improved aeolian sand, and the shear failure mechanism were revealed. The main results show the stress-strain relationship curves of improved aeolian sand are all strain softening curves.The elastic modulus and failure intensity are positively correlated with confining pressure, and elastic modulus reaches to its peak value when the amount of silt mixing is increased to 15%.The value of failure intensity is positively correlated with the amount of silt.The cohesion of modified aeolian sand is the largest under 10% silt mixture, and the internal friction angle increases monotonously with silt mixing amount. The reason is that cement hydrate is wrapped in the surface of sand particles, increasing the surface roughness and forming a network structure in the gap between sand particles.The sand particles are linked together and the relative movement of sand grains is hindered.Incorporating an appropriate amount of silt can fill the gaps between sand particles and hydrates, but excessive silt will restrict the hydration reaction, and at the same time, alkaline ions and hydrates react to produce sodium silicate and sodium aluminate with poor cementing capacity, resulting in a decrease in the overall performance of improved aeolian sand.