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• Time of issue:2020-09-18 10:11
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(Summary description)Several types of soil layers commonly found in pipe jacking machines at this stage: 1. Sandy soil: Because of the impact of the sea surface, the alluvial deposits in some areas have many deposits transported by the sea surface, and the key is fine sand and silty sand. Because it contains less clay, it can be called sandy soil. The soil particles of sandy soil are larger than ordinary clays, generally above 20μ, and the cohesion of the team among the soil particles is smaller, which is a single-grain structure. The void ratio is very large, and it is very easy to cause the quicksand condition under the effect of hydrodynamic force. 2. Micro-weathered and moderately weathered rock: Micro-weathered rock refers to a rock formation with fresh rock quality and slight weathering signs on its surface, with a compressive strength of more than 50Mpa and high strength. In the geological structure here, jacking is difficult, and the blade must be removed and replaced when the jacking distance exceeds 100 meters. Zhongfenghuayan is too soft and part of its organizational structure is destroyed. The mineral composition changes and it is difficult to find with a pickaxe. 3. Strongly weathered rock: Strongly weathered rock refers to a rock layer with strong weathering. Most of the structure of this kind of soil layer has been destroyed, and the mineral composition has changed significantly, with a lot of clay clay minerals. Weathered cracks grow and develop. The rock is cut into broken slag, which can be broken or broken by hand when dry, and it can soften or dissolve more quickly when soaked or wetted. It can be excavated with a pick or spade, and can be drilled in with a pipe jacking machine. 4. Muddy clay: This kind of soft foundation treatment is slowly produced under the poor hydrodynamic effects of large coastal currents and tides. The color of the soil is mostly dark gray or gray-black, shiny and oily, and smells of rotten green plants, and mostly soft or semi-liquid. Its pure natural moisture content is very large, and the pure natural medium-to-severity of soft foundation treatment is relatively small, about 15-19KN/m3. The void ratio is more than 1. Because of its high pure natural moisture content and large void ratio, the soft farmland foundation has the characteristics of large deformation and low compressive strength. 5. Loess: Any earthy deposits that are transported at wind speed and have not undergone secondary oscillations, have no bedding, light yellow texture, contain sulfides, and have perforations visible to the human eye, become loess (also called Original ecological loess), other induced, light yellow soil-like deposits that often have bedding and cracked sand and gravel layers are called loess-like soil (also called secondary loess). The above detailed introduction of several common types of soil layers, from soil layers with N value of 3-40. This requires the use of different types of pipe jacking machines for different soil conditions.