为保障广州地铁某区间盾构隧道正穿上软下硬灰岩地层高速涵洞桩基过程中高速涵洞的安全，选取3种不同加固处理方案进行综合比选后，采取斜向旋喷桩+筏板+复合地基加固处理方案。利用三维有限元对桥梁桩基沉降进行计算预测分析，并与盾构掘进施工监测数据进行比对分析判断。理论计算分析及施工监测结果表明： 1）多角度全方位旋喷加固地层可有效避让既有桩基；调整排泥量、控制地内压力及控制喷射注浆引起的地基隆起与下沉等成桩特点，能有效地降低加固体施工对涵洞桩基的影响，涵洞承台实测沉降量为8.04 mm； 2）盾构掘进正穿过程中，涵洞承台实测总沉降量为10.87 mm，所产生的沉降量均在安全可控范围内，确保了高速及涵洞的正常通行。
To ensure the safety of the highspeed
culvert when a shield tunnel section of Guangzhou metro crossing underneath
pile foundations of a highspeed culvert in upper soft
and lower hard limestone strata, three reinforcement schemes are selected, and
the reinforcement scheme of oblique jet grouting pile + raft board + composite
foundation is adopted. The threedimensional finite
element is used to calculate and predict the settlement of the bridge pile
foundation, and the results are compared with monitoring data. The theoretical
calculation analysis and construction monitoring results show the following:
(1) The multiangle and omnibearing jet grouting can
effectively avoid existing pile foundations, and controlling the mud discharge
volume, ground pressure, and the foundation settlement induced by jet grouting
can effectively reduce the influence of reinforcing construction on culvert
foundation piles. The measured settlement of the culvert cap is 8.04 mm. (2)
During shield tunneling, the measured total settlement of the culvert cap is
10.87 mm, which is within safe and controllable range, resulting in normal
traffic of highspeed viaduct and culverts.
