C4-3-9 block of Hangzhou Economic and Technological Development Zone locates in sand silt ground,and it is retained with technology of I-shaped prefabricated reinforced concrete pile implanted soil-cement.

The dewatering measure combining surface water technology and light well point dewatering on saturated sandy soil stratum according to the favorable water permeability of the soil stratum can effectively lower the underground water level in the stratum and make up the unthorough dewatering of single dewatering technology.

Nanjing silty clay with fine sand interbed is a sediment deposited alternately by silty clay and fine sand, appearing to be a "thousand layers cake"; Nanjing fine sand mainly consists of schistous grain and is different from the common sand with round quartz grains.

For improving roadbed filling by adding quicklime to silty sand, the authors obtain some experimental data about improved soil.

With engineering practice,the article analyzes reasons of ground settlement when shield driving is conducted through sandy silt stratum; and it also sums up the secured measures.

An introduction is given to the comprehensive construction technology for the tunnel with sandy silt and complicated surrounding environment, including waterproof technology, settlement prevention, and old tree protection.

Based on a large amount of field and laboratory tests the standard and methods for the liquefaction evaluation of sandy silt in the old course of Suzhou River are presented.