Formulation of vacuum combined surcharge preloading reinforcement soft foundation

In order to ensure the effectiveness of the anti-seepage curtain, it is recommended that the anti-seepage curtain be carried out before the vacuum preloading and be spaced at a certain time to facilitate the consolidation of the cement mixing pile and the cementing of the mud. It is suggested that the treatment of cement mixing piles should be spaced about 5 days, and the treatment of mud mixing piles should be about 10 days apart. If there are building facilities in the range of 15 to 35m outside the vacuum preloading zone, protective measures should be considered to block the horizontal diffusion of vacuum.

Prior to the development of a program for the vacuum combined surcharge preloading of soft foundations, the engineering geological conditions, hydrogeological conditions and surrounding buildings and facilities must be ascertained. It can effectively shorten the construction period, and the price is relatively cheap in several rapid reinforcement of soft foundations, and it has been rapidly promoted. Through the analysis of the site engineering geological conditions, the physical properties of the soft soil layers can be ascertained, the type of groundwater (confined water, submersible), and the recharge relationship between groundwater and surface water can be ascertained to determine the tightness of the soft ground ( Hermeticity and watertightness). Only when the sealability meets the requirements, a vacuum preloading scheme can be developed.

When analysing the hydrogeological conditions in the field, it is necessary to ascertain the development of the sand interlayer and to find out whether the sand interlayer has water conservancy links with the surface water (river, pond, ditch, and ravine). Generally, a strong permeable layer containing more than 1m in 15m depth can be isolated by deep mixing silt (or cement) to form the underground sealing wall. There must be careful consideration of buildings and facilities in the immediate vicinity. If vacuum preloading must be used, it is recommended that appropriate protective measures be taken to ensure that nearby buildings and facilities are not damaged.