真空-堆载联合预压法加固机理讨论

Mechanism of foundation strengthening by vacuum-surcharge preloading method

根据真空 堆载联合预压现场试验及孔压、沉降测试结果,对真空 堆载联合预压法加固机理中一些有争议的问题,如抽真空时地下水位的变化过程和加固深度范围等,进行了探讨.结果表明:真空预压的直接作用范围可达地表以下18m;真空预压期间地下水位是下降的,且下降幅度小于2m;停止抽真空使地基横向约束放松,从而导致向外变形,且此变形会消除卸真空引起的回弹现象;负孔压的恢复如同正超孔压的消散一样,需要一个过程,即不会瞬时完成.

Based on the measured data of pore water pressure and surface settlement from field vacuumsurcharge preloading tests, some issues in dispute on the vacuumsurcharge preloading strengthening method are discussed, including the variation of groundwater table during the process of vacuumization and the depth of foundation to be consolidated. Some conclusions are drawn: the effective depth of foundations to be consolidated by the vacuum preloading method can reach 18m under the ground surface; the groundwater table declines during the process of vacuum preloading, the range being less than 2m; the stop of vacuumization releases the lateral restriction on the foundation, and further results in its outward deformation, which can eliminate the rebound phenomenon induced by vacuum unloading; and a duration of time is needed for the restoration of the negative pore water pressure, just as for the dispersion of the positive excess pore water pressure.