临江高水位涉京广线基坑工程地下水控制设计

Design of Groundwater Control for the Foundation Pit Engineering Adjacent to the Beijing-Guangzhou Railway in High Water Pressure Area Near the River

为有效控制深基坑工程对邻近在运营京广铁路的影响,满足基坑施工对京广铁路路基附加变形<10 mm的保护要求,除基坑支护体系变形控制外,在临江高水位地区,采用落底式止水帷幕结合坑内管井降水,尽可能减少基坑抽水对京广铁路的影响。以武汉市某临江高水位涉京广铁路线基坑工程为例,基坑采用TRD等厚度水泥土墙、深层搅拌桩止水帷幕落底结合中深管井按需降水措施,利用Midas GTS-NX进行数值模拟辅助计算,在实施过程中对基坑工程和涉京广铁路段进行了详尽的监测。结果表明:基坑临铁侧土体测斜最大值为8.88 mm,轨道水平位移最大值为-2.3 mm,轨道竖向位移最大值为-2.5 mm,路肩水平位移最大值为-2.4 mm,路肩竖向位移最大值为-2.7 mm,有效控制了京广铁路路基、轨道的变形沉降,基坑外水位实测降幅0.8~1.0 m,对京广铁路路基、轨道的影响可控,验证了基坑工程采取的地下水控制措施的有效性。

In order to effectively control the impact of deep foundation pit engineering on the adjacent Beijing-Guangzhou Railway in operation and meet the strict protection requirement of foundation pit construction for additional deformation of the railway roadbed of less than 10 mm.In addition to the foundation pit supporting system deformation control,in high water pressure area near the river,a bottom sealing curtain combined with pipe wells dewatering in the pit is used to minimize the impact of foundation pit pumping on the railway as much as possible.Taking the foundation pit engineering adjacent to the Beijing-Guangzhou Railway in high pressure head area near the river in Wuhan as an example,a TRD equal thickness cement-soil wall and deep mixing pile are used for bottom sealing curtains combined with medium and deep pipe wells to pump water as needed in the foundation pit.The numerical simulation computation is conducted by Midas GTS-NX and detailed monitoring is conducted on the foundation pit engineering and the Beijing-Guangzhou Railway adjacent to the foundation pit during the construction process.The monitoring results indicate that the maximum horizontal displacement of soil adjacent to the railway side of the foundation pit is 8.88 mm,the maximum horizontal displacement of the track is-2.3 mm,the maximum vertical displacement of the track is-2.5 mm,the maximum horizontal displacement of the shoulder is-2.4 mm,the maximum vertical displacement of the shoulder is-2.7 mm.The deformation and settlement of the roadbed and track of the railway are effectively controlled.The measured decline of water level outside the foundation pit is 0.8~1.0 m and the impact on the railway is controllable.The effectiveness of groundwater control measures taken in foundation pit engineering is checked.