In general, in the shield tunnel, bentonite is used to improve the soil?
Grouting grouting duct, injection pump and control system. Shield tunnel through the simultaneous grouting system, slurry injection pipe fittings and open holes into the gap between the annular body, to improve the water resistance of the channel, to prevent the construction area of land subsidence.
On the other hand, due to the timely filling, only to play a good supporting and supporting role, several ring segments to strengthen, reducing the possibility of moving links, thereby reducing the part of the thrust under the crack and possible dislocation.To improve the method of mining sand and gravel silt soil is injected into the chamber of bentonite mud bentonite (mud) system, waste plastic liquidity good, correct consistency, low permeability, Morocco resistance, smooth slag, earth pressure balance control. Typical construction of Beijing shield is sand and gravel layer, each bored ring (1.2 meters), bentonite mud injected 4 square meters. Not only to the mud party requirements and the effect of mud higher requirements. After engineering practice, the proportion of mixing mud 1.07, kinematic viscosity, so that muck improve more than 35 seconds, in order to achieve the best results.
High viscosity of the soil, not easily broken.
In order to solve the loess strata pressure balance shield construction in subway tunnel when the excavated earth pressure, it is difficult to establish and difficult problems such as high cutting temperature, using bentonite and modified foam on the muck to ensure the shield effect
