考虑砂土压密特性的劈裂注浆机理分析

Analysis of splitting grouting mechanism considering sand compaction characteristics

砂土自身压密特性对浆液扩散形态具有显著的调控作用,“浆-土”耦合效应下的劈裂注浆机理分析需妥善考虑砂土的压密特性。通过调整黏性土含量与初始含水率,对砂土压密特性进行了试验研究。试验表明黏性土是影响砂土压缩变形的重要因素,黏性土含量低时砂土内部形成砂骨架,砂层整体抗压缩性较强;黏性土含量超过临界值后,砂土内部难以形成有效抵抗外荷载的骨架体,砂土可压缩性发生质变。基于二次函数模型对砂土非线性压密过程进行描述,模型采用砂土初始压缩模量Es0和终级荷载下的极限应变εu进行表征,可准确应用于“浆-土”耦合效应下的注浆设计计算。注浆条件相同的情形下,劈裂通道宽度随黏性土含量增加而增加,浆液扩散半径及压力随黏性土含量增加而减小。在相同注浆终压条件下,浆液劈裂扩散极限距离与黏性土含量呈正相关特性。该研究结果可为堤防、桩基等砂土场地工程建设提供科学指导。

The self compaction characteristics of sand have a significant regulatory effect on the diffusion pattern of slurry.The compaction characteristics of sand should be properly considered in the analysis of splitting grouting mechanism under the“slurry soil”coupling effect.By adjusting the content of cohesive soil and initial water content,the compaction characteristics of sand are studied.The test shows that cohesive soil is an important factor affecting the compression deformation of sand.When the content of cohesive soil is low,sand skeleton is formed in sand,and the overall compression resistance of sand layer is strong.When the content of cohesive soil exceeds the critical value,it is difficult to form a skeleton in the sand to effectively resist the external load,and the compressibility of the sand changes qualitatively.The nonlinear compaction process of sand is described based on the quadratic function model,the model adopts the initial compression modulus of sand Es0 and the ultimate strain under the final loadεu,which can be accurately applied to the grouting design calculation under the“slurry soil”coupling effect.Under the same grouting conditions,the width of splitting channel increases with the increase of cohesive soil content,and the slurry diffusion radius and pressure decrease with the increase of cohesive soil content.Under the same final grouting pressure,the limit distance of grout splitting diffusion is positively correlated with the content of cohesive soil.The research results can provide scientific guidance for the construction of sandy soil sites such as embankments and pile foundations.