1 Cement mixing pile Deep cement mixing pile uses cement as the main agent of curing agent, and forcibly mixes soft soil and curing agent in the deep part of foundation through special deep mixing machinery to harden soft soil and improve foundation strength. This method is suitable for soft soil treatment, and the treatment effect is remarkable, and it can be put into use after treatment. In terms of construction methods, according to the state of using reinforcement materials, it can be divided into slurry mixing method (wet method, that is, cement deep slurry mixing method in these rules) and powder mixing method (dry method).
2. High-pressure jet grouting pile The high-pressure jet grouting pile uses a drilling machine to drill grouting pipe with a nozzle into a predetermined position in the soil layer, and then the slurry is ejected from the injection port in the form of high-pressure flow, which impacts and destroys the soil. The high-pressure water flow cuts the crushed soil layer and the particles are dispersed. One part is carried out of the hole by mud and water, and the other part is stirred and mixed by mud. With the stirring and mixing of the slurry, the spray pipe continuously rotates and lifts 360 degrees. With the solidification of the slurry, the composition has certain strength and resistance. In terms of construction methods, single pipe method, double pipe method and three pipe method can be adopted respectively; In the form of spray, it can be divided into three types: rotary spray, fixed spray and oscillating spray.
Second, the machines are different.
1, cement mixing pile PH-5 series deep mixing pile machine and corresponding auxiliary equipment (mortar pump, mortar mixer and other equipment for preparing cement slurry).
2. High-pressure jet grouting pile machine, high-pressure plunger pump, air compressor, mud mixer, grouting pump, sewage pump and other equipment.
Third, the process is different.
1, release the position of cement mixing pile → put the drilling rig in place → check and adjust the drilling rig → drill in positive circulation to the design depth → turn on the high-pressure grouting pump → drill in reverse circulation and shotcrete → drill 0.3m→ below the working datum → repeatedly stir and shotcrete to the design depth → drill in reverse circulation to the surface → finish piling → construct the next pile.
2, high-pressure jet grouting pile lofting → drilling rig in place → pilot hole (reaming) to design elevation → plugging vertical nozzle → mixing slurry → bottom-up jet grouting → flushing → replacement.
Fourth, the applicable soil layers and uses are different.
1. Cement mixing pile Cement mixing pile is suitable for treating normally consolidated silt and muddy soil, plain fill, silt, cohesive soil and loose sand, and there is no flowing groundwater. The depth of reinforcement is generally greater than 5.0m According to the engineering geological conditions of the site, the load requirements of the superstructure and the stress state of the cement-soil pile, the cement-soil formed by the deep mixing pile can be used as the retaining wall and impervious curtain of the foundation pit project. Vertical bearing composite foundation; Mass cement stabilized soil, etc. The shape of deep stirred solids can be divided into column, wall, grid and block. Among them, the form of column plus solid is mostly used for composite foundation reinforced by soft soil; Wall, grid and solid are mainly used as retaining walls and impervious curtains for deep foundation pit excavation; Block-plus-solid form is mostly used for structural foundations with large load per unit area of superstructure and strict control of uneven settlement.
2. The high-pressure jet grouting pile is suitable for treating silt, muddy soil, flowing plastic, soft plastic or plastic cohesive soil, plain fill, silt, sandy soil, gravel soil and other soil layers. When the soil layer contains more large-grained stones, a large number of plant roots or more organic substances, and the groundwater velocity is too high, it should be used cautiously or its applicability should be determined according to the field test results. The reinforcement depth is generally greater than 5.0m The jet grouting pile (adding solid) can be used for foundation reinforcement of existing buildings and new buildings, and soil reinforcement or waterproofing of deep foundation pits, subways and other projects. However, in the foundation pit enclosure engineering, it is often used as impervious curtain wall alone in the form of fixed spray or swing spray, or as impervious retaining wall in combination with anti-horizontal row piles (directional swing spray between piles).