What is high-pressure rotary excavation pile?
High-pressure jet grouting pile is to inject cement slurry into the soil layer by using high-pressure rotary nozzle and mix it with soil to form continuous overlapping cement and solid. The construction occupies less land, has little vibration and low noise, but it is easy to pollute the environment and has high cost, so it is not suitable for special soil that cannot be solidified by shotcrete.
Scope of application of high-pressure jet grouting pile:
(1) High-pressure jet grouting method is suitable for treating silt, muddy soil, flowing plastic, soft plastic or plastic cohesive soil, silt, sandy soil, loess, plain fill and gravel soil.
(2) When the soil contains a large number of large-size stones, hard clay, a large number of plant roots or too much organic matter, the applicability of silt, peat soil and collapsible loess foundation reinforcement should be determined according to the field test results. Its applicability and technical parameters should be determined by high-pressure jet grouting test.
(3) High-pressure jet grouting method should be used with caution in foundation projects with excessive groundwater velocity and large water inflow, for the stratum with pebble, block and boulder skeleton structure in bedrock and gravel soil.
(4) The high-pressure jet grouting method can be used for foundation reinforcement of existing buildings and new buildings, water-stop curtain of deep foundation pit, retaining soil or water on slopes, foundation pit bottom reinforcement, prevention of piping and uplift, plugging and reinforcement of underground large-diameter pipelines, soil layer reinforcement or waterproofing of subway projects, reservoir dams, seawalls, river dikes, dam foundation seepage prevention and dam interception of underground reservoirs.
Basic provisions of high-pressure rotary excavation pile:
(1) The design and construction of high-pressure jet grouting foundation engineering should be adapted to local conditions, and factors such as foundation type and nature, groundwater conditions, superstructure form, load, site environment, performance of construction equipment, etc. should be considered. Comprehensive consideration should be taken to ensure the quality of the project.
(2) The grouting forms of high-pressure jet grouting method are divided into three categories: rotary jet grouting, swing jet grouting and fixed jet grouting. According to the engineering needs and equipment conditions, single pipe method, double pipe method and three pipe method can be used respectively, and the three-dimensional shape can be divided into cylindrical, fan-shaped block, wall and plate.
(3) High-pressure jet grouting, fixed jet grouting, swing jet grouting, large-angle swing jet grouting and rotary jet grouting are suitable for loose stratum, gravel stratum and bedrock eluvial layer with particle sizes not more than 20mm, 60mm and 100mm respectively.
(4) When formulating the high-pressure jet grouting scheme, we should master the engineering geology, hydrogeology and architectural structure design data of the site. For existing buildings, relevant historical and current information, adjacent buildings and underground buried objects should be collected.
(5) After the scheme of high-pressure jet grouting is determined, field test and pilot construction should be carried out in combination with the engineering situation, or the construction parameters and technology should be determined according to the engineering experience.
(6) The test site of high-pressure jet grouting should be selected in the representative section of the whole project, and the test can reflect the reinforcement or anti-seepage effect of high-pressure jet grouting on foundation treatment engineering.
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