不同夯点布置形式下群夯加固效果研究

强夯作为一种高效的地基加固技术已被广泛地应用于各类工程建设中，针对强夯的理论研究主要集中于单点夯作用下的土体响应方面，对群夯作用下相邻夯点的相互作用研究较少。为研究不同夯点布置形式对强夯加固效果的影响，在LS-DYNA的框架内，采用非线性大变形显式有限元算法和“帽子”本构模型计算了强夯作用下土体的压密程度。首先，基于单点夯试验，通过夯周土体侧向位移的数值计算结果与实测数据的对比，验证了模型的合理性。在该基础上对菱形、正方形两种常见夯点布置形式下的强夯施工过程进行了数值模拟，研究不同夯点布置形式对强夯过程中土体压密程度的影响。结果表明，夯点间土体同时受相邻夯点的影响，临近后期夯点的一侧土体的加固效果要优于临近先期夯点的一侧；夯点按菱形布置（等边三角形）时土体的加固效果要优于夯点按正方形布置（等腰直角三角形）。此外，夯坑深度、有效加固深度可以将强夯影响深度以内的土体划分为土体剪胀区、强加固区和轻微扰动区三部分。

Study on multi-tamping effects under different arrangement forms of tamping location

As an efficient foundation reinforcement technology, dynamic compaction technology has been widely used in various engineering constructions. However, most related theoretical research mainly focus on the tamping at a single location, and the interaction between adjacent tamping points under tamping at several locations simultaneously is rarely studied. In order to investigate the reinforcement impacts of multi-tamping under different arrangement forms of tamping location, the geometric nonlinear finite element method for large deformation and the constitutive model of “cap” in the framework of LS-DYNA are applied to analyze the degree of soil compactness under strong tamping at multi-locations. Firstly, based on the tamping experiment at a actual situation of site construction, the rationality of the model is verified by comparing the numerical results with the measured data for the lateral displacement in the soil around the tamping points. Moreover, considering two common arrangements of tamping points (i.e. rhombus-grid pattern and square-grid pattern), numerical simulations are carried out on the dynamic construction process, and compaction degree of the soil under different layouts of tamping points are studied. The results show that the compacted area between adjacent tamping locations is susceptible to multi-tamping effects, and the reinforcement degree of soil near the subsequent tamping location is better than that near the previous tamping location. Besides, the reinforcement of soil is better in regions applying rhombus-grid tamping points compared with that of square-grid pattern. In addition, by using the depth of the crater and the effective reinforcement depth, the soil affected by the strong tamping can be divided into three parts: the dilatation zone, the strong reinforcement zone and the slightly disturbed zone.