劈裂真空法加固软土室内模型试验研究  

Model test study on reinforcement effect of combined method of vacuum preloading and pneumatic fracturing

作　　者：韩文君[1,2] 刘松玉[1] 章定文[1] 

机构地区：[1]东南大学,江苏南京210096 [2]常州市轨道交通发展有限公司,江苏常州213022

出　　处：《土木工程学报》2013年第10期108-118,共11页China Civil Engineering Journal

基　　金：国家自然科学基金(51078083)

摘　　要：劈裂真空法是综合真空预压法和气压劈裂技术的优势而形成的一种加固软土地基的新技术。为深入揭示其加固机理，设计劈裂真空法室内模型试验装置，进行劈裂真空法与常规真空预压法加固软土对比试验，对加固过程中真空度、孔隙水压力、土体变形、气压劈裂参数进行监测，并采用十字板剪切试验和取样室内试验对两种方法加固前后土体物理力学指标进行对比分析。加固过程监测结果表明：气压劈裂可改善真空度在排水体中的传递效率，水平布置的真空度测头变化规律证实在喷气点深度形成了水平向的裂隙；劈裂真空法加固软土的超静孔压消散速率和土体沉降速率都明显快于常规真空预压法，工后沉降量小于常规真空预压法。加固效果评价试验结果表明：劈裂真空法使得加固后土体含水量小于常规真空预压法，且远离排水边界的土体差异更为显著；劈裂真空法加固土体强度增长最大幅度较常规预压法提高1．5—2．0倍。模型试验表明，劈裂真空法新技术可缩短地基固结时间，提高加固效果。A combined method of vacuum preloading and pneumatic fracturing is used to improve the soft ground. In order to investigate the mechanism of the proposed method, a new model test apparatus is developed and compared with the traditional vacuum preloading method. The vacuum pressure, pore water pressures, settlements are monitored during the model tests. The vane shear test and soil tests are used to evaluate the effect of the proposed method. The model tests results indicate that the transfer efficiency of vacuum degree in the proposed method is better than that of the traditional vacuum preloading method, and pneumatic fractures are concentrated on jet depth in horizontal direction. The dissipation rate of excess pore pressure and settlement rate of the proposed method are both faster than the traditional vacuum preloading method. The decrease degree of the soil water content under the proposed method is larger than the traditional vacuum preloading method, especially when the soil is away from the drainage boundary. The strength increase induced by the proposed method is 1.5 to 2.0 times the traditional vacuum preloading method. The model tests show that the combined method of vacuum preloading and pneumatic fracturing can increase the reinforcement effect and reduces the preloading time of the vacuum loading.

关 键 词：劈裂真空法 裂隙 加固效果 模型试验 

分 类 号：TU472.99[建筑科学—结构工程]