砂层基础的运营地铁隧道异常沉降治理措施研究

砂层基础的运营地铁盾构隧道异常沉降极易引起管片破损、错台、渗漏和道床脱空剥离等表观病害，严重危及隧道结构及运营安全。因地铁运营线路治理环境的特殊性，难以及时采取隧外地面注浆的治理措施控制沉降，难以保障结构治理的时效性。因此，采取隧道底部钻孔注射超细水泥浆的治理方案，并通过跟踪监测对治理效果进行检验。结果表明，隧道底部注浆治理方案可快速有效地控制运营地铁隧道异常沉降。注浆之前应首先进行隧道渗漏治理，避免水土流失影响沉降治理效果。超细水泥因其浆液颗粒小、和易性好，可有效充填和固结砂层，同时避免注浆扰动基础引起的隧道二次沉降。通过跟踪监测，治理后的隧道沉降速率满足规范要求。

Study on Differential Settlement Control Measures of Subway-Operated Tunnel above Sand Layer

Differential settlement of a subway shield tunnel in operation can easily initiate superficial disorders, such as a segment crack, segment dislocation, leakage, and track bed disengaging, that seriously affect the tunnel structure and operation safety. Because of the complicated environment of the subway, it is difficult to control the settlement without a delay by ground grouting measures. Hence, ultrafine cement was injected into the newly drilled holes at the bottom of the tunnel. The correction effect was then evaluated by a long-term monitoring. The monitoring results show the following: 1) the injection into the bottom of the tunnel can efficiently control the differential settlement; 2) to avoid water and soil loss during the injection, it is necessary to treat the leakage beforehand; 3) ultrafine cement can richly fill and reinforce the sand layer, because of its fine grout granules and good workability, and avoids any secondary settlement caused by a lower soil disturbance during injection; and 4) the settlement speed after treatment conforms to the code requirement.