增压式真空预压处理站场软基效果试验研究

常规真空预压由于工期长、长期排水效果差,常常无法满足站场路基设计施工要求;为克服上述缺点,在某站场地基处理过程中引入增压式真空预压。为验证增压式真空预压的适宜性,在现场设置4个不同设计方案的试验断面,分别进行表层沉降、分层沉降、孔隙水压力和地下水位的对比分析。试验结果表明:采用增压式真空预压可提高预压期沉降量,缩短固结时间;但增长效果主要体现在增压管埋设深度以下2 m左右的位置,其沉降量约占总沉降的70%;增压处理后能有效降低真空预压区地下水位,加速软基固结。

Experimental Study on Air-boosted Vacuum Preloading of Soft Station Foundation

The usual vacuum preloading process cannot meet design and construction requirements of foundations of station tracks because of its long construction periods and poor soil water drainage effect.To overcome those disadvantages,the air boosted type of vacuum preloading was introduced in construction of the foundation of a station.Test sections for four different design alternatives were set up on the construction site to measure and compare the settlement of the surface layer,the settlement by layer,the pore water pressures and ground water levels and to verify the applicability of the air-boosted vacuum preloading technology.The test results show as follows: The booster-type preloading increases the settlement during pre-compaction and shortens the consolidation time;the increment of settlement was mainly generated 2 meters below,the buried depth of the booster tubes,and it occupies about 70% of the total settlement;air-boosting treatment effectively reduces the ground water level in the vacuum preloading area and accelerates consolidation of the soft foundation.