Pre-treatment of tank foundation

The choice of foundation treatment method depends on the geological conditions, and there is no universal solution； Pneumatic jet grouting = Cement-soil mixing method (dry method). \"Technical Code for Foundation Treatment in Buildings\" JGJ 79-2002 ★11.1 Mixing piles 11.1.1 The cement-soil mixing method is divided into the deep mixing method (hereinafter referred to as the wet method) and the pneumatic jet mixing method (hereinafter referred to as the dry method). The cement-soil mixing method is suitable for treating foundations such as normally consolidated silt and silty soil, silt, saturated loess, plain fill, clay, and saturated loose sand without flowing groundwater. The dry method should not be used when the natural moisture content of the underlying soil is less than 30% (less than 25% for loess), greater than 70%, or when the pH value of groundwater is less than 4. During winter construction, attention should be paid to the impact of low temperatures on the treatment effect. 11.1.2 The cementitious mixing method is used for treating peat soils, organic soils, clays with a plasticity index Ip greater than 25, in situations where groundwater is corrosive, and in areas lacking engineering experience; its suitability must be determined through field tests. 11.1.3 The cement soil solidified by the cement-soil mixing method can be used as a composite foundation with vertical bearing capacity ； Retaining walls for foundation pit works, reinforcement of passive zones, impermeable curtains ； Massive cement-stabilized soil, etc. The shape of the reinforcing body can be cylindrical, wall-like, grid-like, or block-like, etc. 11.1.4 Before determining the treatment plan, comprehensive geotechnical data for the area to be treated should be collected. In particular, the thickness and composition of the fill layer ； Distribution range and stratification of soft soil layers ； Groundwater level and pH value ； The moisture content, plasticity index, and organic matter content of the soil, etc. ★6.1 Dynamic compaction method and dynamic compaction replacement method 6.1.1 The dynamic compaction method is suitable for treating foundations made of gravelly soil, sand, low-saturation silt and clay, collapsible loess, plain fill soil, and mixed fill soil. The dynamic compaction replacement method is suitable for projects on foundations such as highly saturated silt and soft-plastic to fluid-plastic clays, where strict control over deformation is not required. 6.1.2 The dynamic compaction replacement method must have its suitability and treatment effectiveness determined through field tests prior to design. 6.1.3 Before carrying out dynamic compaction and dynamic compaction replacement works, one or several test areas should be selected at representative sites on the construction site to conduct trial compactions or experimental construction. The number of test areas should be determined based on the complexity of the construction site, the scale of the building, and the building type.