土岩复合地层土压平衡盾构渣土改良试验研究

Experimental Study on Soil Conditioning for Earth Pressure Balance Shield Tunneling in Soil-rock Composite Stratum

土压平衡盾构施工地铁隧道时经常会遇到土岩复合地层,在该类地层中掘进时,泡沫注入比更加难以确定。以深圳市地铁12号线某区间隧道土岩复合段为例,进行了室内泡沫改良剂试验、全风化混合花岗岩和土岩复合地层渣土改良试验。试验结果表明,在土岩复合地层中,掌子面土体占比每降低10%,泡沫注入比应当增加约50%,坍落度在100~220mm。通过工程实例发现,在土岩复合段内,泡沫注入比的增加有助于土压舱内建立稳定的土压力。

When the earth pressure balance shield is used to construct the subway tunnel in soil-rock composite stratum, it is harder to determine foam injection ratio. Based on the EPB section in soil-rock composite stratum of Shenzhen Subway line 12, indoor foam modifiers, soil conditioning in completely weathered mixed granite and soil-rock composite stratum were carried out in laboratory. The results show that the soil mass ratio on tunnel face is reduced by 10% in soil-rock composite stratum, the foam injection ratio should increase by about 50%. The slump is in the range of 100~200 mm. Through the engineering example, it is found that the increase of foam injection ratio in soil-rock composite stratum is helpful to establish stable earth pressure in the earth pressure chamber.