Safety technology for soft soil foundation treatme

Safety technology for soft soil foundation treatment of deep foundation pit

the site of water pump house in XX new campus includes three parts: power distribution center, pool and water pump house. The site covers an area of nearly 1350M2. The groundwater pool area on site has been excavated downward by about 5m, the excavation depth of the basement in the water pump room area in the future is about 5m, and the buried depth of the basement and foundation of the distribution center is considered to be about 2m. Due to the influence of the geological conditions of the site, the bearing capacity of the basement foundation of the three parts of buildings (structures) can not meet the design requirements (140 can we still get a reliable material mechanics process experimental scheme from the manufacturer and a complete set of consulting, training, and related protection and maintenance services kPa of the equipment of the physical and chemical laboratory), so it is considered that this part of the site adopts static pressure grouting for foundation treatment

divide the static pressure grouting plane into four annular areas, namely u+2460, u+24 others from outside to inside: four strips of sliding friction 61, u+2462, u+2463 for plastic products and rubber products or other composite materials, which adopt different hole spacing respectively, and the general principle is dense outside and sparse inside. The construction shall be carried out from the outside to the inside to prevent excessive loss of grout

2. Quality assurance measures for static pressure grouting construction

design requirements for static pressure grouting

(1) the foundation of the project is reinforced by static pressure grouting method. The reinforcement object is the loose fill layer, and the silty clay does not need to be reinforced by grouting. Due to the small scope of the local muddy soil corresponding to ZK6 hole in the survey report, the grouting hole centered on it and within 3m in diameter was grouted with high-pressure splitting grouting treatment at the bottom 2m (i.e. the sludge part) of the process of data recording and data calculation. The bearing capacity of the reinforced foundation is required to reach 140kpa

(2) at present, the grouting area has been excavated to the base, and the depth of the grouting hole is required to drill through the filling layer, with a depth of 1-4m. Each hole adopts the segmented grouting method, with a section length of 500. The average cement consumption per meter of each hole in ＼ u+2460 area and ＼ u+2461 area is between kg, ＼ u+2462 area and ＼ u+2463 area is between kg. The standard for terminating grouting is that the grout returns from the orifice and has reached the minimum grouting amount required by the design; Second, the orifice has not returned grout, but the grouting volume has been 6. The standard accessories of battery acupuncture experimental machine: it has reached the upper limit of cement consumption per meter. Third, although it has not reached the minimum grouting volume required by the design, the orifice has returned grout, and it is confirmed by field verification that the stratum is dense, and the groutability is really poor

(3) pour pure water slurry, with water cement ratio of 1:1 (unit weight 1.49) - 0.75:1 (unit weight 1.62), and add early strength agent CaCl accounting for 2% of cement weight

(4) because there are many stones in the filling layer, it is difficult to form holes. In order to improve the work efficiency, the static pressure grouting method is combined with the machine drilling pre hole section grouting method and the hitting steel flower pipe section grouting method. The drilling grouting method adopts 1:1 cement slurry circulation to protect the wall, pre grouting once per LM of drilling from top to bottom, and then replace with 0.75:1 cement slurry from bottom to top after finishing the hole, and refill once every 50cm. The flower tube grouting method adopts the bottom-up segmented grouting method, and grouting once every 50cm

(5) in order to ensure sufficient overburden pressure, before grouting, it is required to pour the base surface with cement slurry with a water cement ratio of 0.5:1 (volume weight 1.86) to solidify the surface layer within a range of about 50cm (the amount of cement is about 50kg/m2)

(6) construction quality inspection: (1) excavation inspection apparent quality: more than 70% of the voids within the diameter of the grouting hole LLM have been filled with grout consolidation body, and the soil is plastic. (2) Heavy dynamic penetration test; (3) Bearing capacity test: 2 weeks after construction × 2m plate load test, a total of 3 points or as specified in the specification