苏州粉土地层地连墙施工对地层扰动影响研究

Study of silty soil behavior disturbed for installation of diaphragm wall in Suzhou

采用三维有限差分软件FLAC3D对地下连续墙施工进行模拟,分析苏州地区粉土地层中地连墙施工对土体扰动及周边建筑物影响。利用UBCSAND硬化规律对外部扰动作用下土体强度逐步发挥的力学特性进行表征,模拟开挖过程中浅层土体变形,并对地连墙施工中成槽开挖、钢筋混凝土施工及混凝土硬化进行全过程模拟。计算结果表明,硬化模型较好地反映地连墙施工扰动下浅层土体力学特性;地连墙成槽阶段地层变形随深度的增加而减小,地表以下20 m范围内地层变形显著,而深部土体变形较小;钢筋混凝土浇筑施工对地层变形起到抑制作用;混凝土硬化阶段地层变形趋于稳定。在该基础上采用硬化模型对苏州某基坑地连墙施工进行数值仿真,模拟结果和现场实测吻合较好。

This paper investigates the soil behavior and adjacent building settlement disturbed by the installation of diaphragm wall. This investigation is carried out by the numerical software FLAC3 D; and in this simulation, the UBCSAND model is adopted for the modelling. The feature of strain strengthen in this model is able to characterize the soil behavior at shallow depth. The trench excavation, cage reinforcement, concreting, and concrete hardening, involved the installation of wall panel is carefully simulated. The results show that: Thanks to the hardening model, the soil movement at the shallow depth is well simulated. At the depth smaller than 20 m below the ground surface, the trench excavation caused a significant soil movement. The movement decreases with the depth and it maintains tiny in deep soil. The cage reinforcement and concreting alleviates the trend of the movement. During the concrete hardening, the soil movement tends to be stabilized. A project of diaphragm wall in Suzhou is re-examined by using the new model. The numerical results are consistent with the in-situ measurements.