开行大轴重列车既有线隧道基底病害的井点降水整治方案研究

Study on the Treatment Scheme for Diseases in Tunnel Base by Well Point Dewatering under the Condition of Heavy Axle Load Train on Existing Railway

为整治某开行大轴重列车既有线隧道基底下沉及翻浆冒泥病害,采用钻探与物探相结合的检测手段进行隧道病害区段检测。检测结果表明,隧道病害区段底板混凝土为素混凝土且较薄(25cm左右),基岩与混凝土间存在厚度约5cm的软弱夹层,病害区段基底含水量较大,导致底板混凝土破损严重。在掌握隧道基底现状的基础上,确定对其采用"井点降水+注浆"复合式整治措施。通过理论计算、降水效果的数值分析和施工可行性分析并兼顾工程造价确定的具体方案为:单侧降水,井点系统布置于重车线外侧,在100m病害区内按间距2m布设50根井点管;注浆在重车线轨枕头两侧实施,注浆管直径为60mm,长度2m,间距1m,注浆压力0.3MPa。"井点降水+注浆"整治措施实施后,该区段基底水位始终保持在基底下1.5m左右,再无基底下沉及翻浆冒泥病害发生,说明采用该方案是有效的。

In order to treat the diseases （such as base subsidence and mud pumping） in tunnel under the condition of heavy axle load train on certain existing railway, drilling combined with geophysical drilling detection methods were used for detecting the disease section of tunnel. Detection results show that the base plate of tunnel disease section is plain concrete and is thinner （25 cm or so）. There is a weak interlayer of about 5 cm between the bedrock and concrete. The water content of the base in disease section is greater, which causes serious damage of base plate concrete. On the basis of mastering the present situation of tunnel base, treatment measure by combining well point dewatering and grouting is put forward. Through theoretical calculations, the numerical analysis of dewatering effect, construction feasibility analysis, and taking into account construction costs, the specific programs are determined as follows. Unilateral dewatering is adopted, and then well point system will be arranged in the lateral line of heavy vehicle. Fifty well points will be laid in 100 m disease section with the spacing of 2 m. Grouting is carried out at both ends of the sleeper in heavy vehicle line. Grouting pipe diameter is 60 mm, length is 2.0 m, spacing is 1.0 m, and grouting pressure is 0.3 MPa. After the treatment measure by combining well point dewate- ring and grouting has been implemented, the water level of the tunnel base in this section always keeps at about 1.5 m under the base. No such diseases as base subsidence and mud pumping occur, which indicates that the measure is very effective.