西气东输管道工程中卫黄河穿越隧道场地工程地质条件评价

西气东输工程中卫黄河穿越隧道长1197.77m,高4.3m,宽5.6m。隧道入口高于黄河水位28m,出口高于黄河水位45m。隧道顶板高程为1130m。位于黄河水下100m。隧道场地围岩为寒武系磨盘井组灰绿色、银灰色浅变质中厚层细粒长石石英砂岩、千枚状板岩、绢云母化千枚岩。围岩为弱风化Ⅲ～Ⅳ类岩石。透水率为4～67Lu,纵波波速为500～3300m.s^-1。BQ为300～400。变形模量为6.11～9.22GPa。泊松比（μ）0.14～0.24。内摩擦角（ψ）为42.1°～44.7°。地下水为基岩裂隙水。含水层为寒武系浅变质岩,受大气降水渗入补给,单井涌水量为1.0～50m³.d^-1。隧道轴线穿越区岩体较完整—较破碎,未有全新活动断层。隧道位置选择和开挖深度设计是可行的。施工和长期运营是安全的。

EVALUATION OF ENGINEERING GEOLOGICAL CONDITIONS FOR A LARGE GAS PIPELINE TUNNEL CROSSING YELLOW RIVER AT ZHONGWEI,NINGXIA PROVINCE

This paper presents the evaluation of the engineering geological conditions for a large tunnel crossing Yellow River at Zhongwei.The tunnel is to transport gas from the western China to-the eastern China and is 1197.7 7m long and 4.3 m high and 5.6 m wide.The elevation of the tunnel ceiling is 1130 m above the sea level and 100 m below the Yellow River.The surrounding rocks are the Cambrian rocks,Mopanjing Formation and include celadon and silver-gray metamorphic medium heavy bedded fine-granular feldspar quartz sandstone and phyllitic slate and sericite phyllite.The class of the surrounding rock quality is III-IV.The permeable ratio is between 4 and 67 Lu,the P-wave velocity is from 500 to 3300 m·s^-11.The BQ value is between 300 and 400.Modulus of deformation is between 6.11 and 9.22 GPa.Poisson’s ratio is between 0.14 and 0.24.The internal friction angle（ψ） is between 42.1 ° and 44.7°.The groundwater is the water in fissures of the bedrock.The aquifer supplied by atmospheric precipitated water is the agnostogenic rocks of the Cambrian system.The seepage capacity of a signle well is 1.0 ～50 m³ per day.The traverse rock tunnel axis is from relative intact to relative broken rocks,and has no active faults.The alignment and depth of the tunnel design is adequate and feasible.The construction and long-term operation are safe.