土压平衡盾构侧穿富水地层铁路桥桩施工技术

济南地铁某土压平衡盾构区间隧道处于上部为可塑黏土、下部为碎石土的富水地层中,且近距离侧穿底部净空较小的铁路客专桥桩。施工中,在桥桩与隧道间设置钻孔灌注隔离桩进行隔离防护,隔离桩顶部施工钢筋混凝土连梁以提高灌注桩抵抗变形的能力;选用护壁性能好、低高度的正循环钻成孔,钢筋笼分段制作、吊装,机械连接下井后及时灌注混凝土;采用微过土压平衡掘进模式,并进行足量同步注浆、及时二次补充注浆,可有效控制地面沉降,满足铁路客专及桥梁的各项控制指标要求。

Construction technology of railway bridge pile passing through water rich stratum by EPB shield

An EPB shield tunnel of Jinan metro is located in the water rich stratum with plastic clay in the upper part and gravel soil in the lower part,and it passes through the high speed railway bridge pile with small clearance at the bottom at short distance.During the construction,bored castin-place isolation piles are set between the bridge pile and the tunnel for isolation and protection.Reinforced concrete coupling beams are constructed at the top of the isolation piles to improve the resistance of the cast-in-place piles to resist deformation.Positive circulation drilling with good retaining wall performance and low height is used to drill holes.The reinforcement cages are fabricated and hoisted section by section,and the concrete is poured in time after the mechanical connection is lowered into the well.The balanced driving mode EPB of micro earth pressure is used,and sufficient quantity of synchronous grouting and timely secondary supplementary grouting effectively controls the land subsidence and meets the requirements of various control requirements of railway high speed line and bridge.