劈裂真空法加固软土地基试验研究

在分析常规真空预压法加固软土地基局限性的基础上，提出了劈裂真空法加固深厚软土地基新技术。介绍了劈裂真空法的基本原理和施工工艺。依托江苏省江海高速公路软基处理项目进行了劈裂真空法与常规真空法加固软土地基的对比试验段工程，对软基加固过程中的真空度、孔隙水压力、地表沉降、深层水平位移和地下水位等进行监测，并通过加固前后现场 CPTU 原位测试、取样和室内土工试验等方法对加固效果对比分析。试验结果表明：劈裂真空法可以提高真空荷载向深层土体的传递效率，提高深部软土的加固效果，进而提高真空预压法的有效处理深度；同时劈裂真空法还可以加速地基固结，缩短地基处理工期，有利于工后沉降的控制。试验工程表明，劈裂真空法是加固深厚软土地基的有效方法，具有很好的工程应用前景。

Field pilot tests on combined method of vacuum preloading and pneumatic fracturing for soft ground improvement

To overcome the shortcomings of the traditional vacuum preloading method,a new technique is proposed to combine the vacuum preloading with the pneumatic fracturing.This study presents the concept,mechanism,construction procedures and field validation of this new combined method.Field pilot tests were conducted to compare the performances of the proposed new method and the traditional vacuum preloading method in a construction section of Jiangdu-Haian highway.The vacuum degrees,pore water pressures,surface settlements,deep horizontal displacements and groundwater levels were monitored during the field tests.The effectiveness of soft ground improvement is demonstrated by the comparison of CPTU tests and soil property tests before and after ground treatment.The test results show the improvement effects of the proposed method are better than those of the traditional vacuum preloading method by enhancing the vacuum transfer efficiency into the deep soil layers.The proposed method raises the effective treatment depth of the vacuum preloading method and reduces the preloading time of the vacuum loading.The combined method of vacuum preloading and pneumatic fracturing can be widely used in the improvement practice of soft ground.