含承压水软基真空联合堆载预压加固试验研究

运用真空联合堆载预压法加固含承压水软基,简要介绍了防止承压水贯通的施工工艺。对港湾变电所软基加固试验中的地表沉降、分层沉降、土体深层水平位移和出水量等现场测试结果进行了分析。试验结果表明:真空联合堆载能有效消除含承压水层软基沉降,地基平均固结度为83%,工后沉降较小,能满足变电所软基工后沉降要求。对地基土体的加固效果进行了室内和现场试验。结果表明:真空联合堆载预压后土体的抗剪强度和承载力显著提高,加固效果十分明显。从单泵出水量和承压水层的压缩量来看,真空联合堆载预压过程中并未贯通承压水地层。加固后软基底部含水率比中部小,表明底部软土层向圆砾层排水加速软基固结。试验的成功进一步拓展了该法的应用领域,对类似地质条件下的真空联合堆载预压设计、施工和科研具有借鉴意义。

Field tests on soft soil with confined underground water by vacuum-surcharge preloading

Soft clay deposits with confined underground water were strengthened by vacuum-surcharge. Technology of the tearing membrane combined with the non-tearing membrane was introduced. The details of settlements, multi-point settlements and deep horizontal displacements were presented and analyzed for the field tests on Gangwan substation. It was shown that the main settlements could be eliminated effectively by vacuum-surcharge preloading at soft foundation with confined underground water, the average degree of consolidation of soft soil was 83% which would last for more than 100 years. The shear strength and bearing capacity of silt would increase obviously after preloading as indicated by indoor and outdoor comparison tests. Viewed from the flow of single pump and the compression of stratum with confined underground water, the lower confined underground water was not influenced by vacuum loading. The success of this technology would promote greatly the application of vacuum-surcharge preloading.