某土质遗址包气带水分布特征及其对遗址保存的影响

Characteristics of Water Distribution in Vadose Zone in the Soil Siteand Its Impact on Site Preservation

土质遗址受水的影响易产生开裂、酥化、返盐、青苔等病害,不利于遗址的保存。为探明土体水害来源,为土质遗址保存提供可靠依据,在精细化水文地质勘察的基础上,借助Solinst Levelogger地下水记录仪、MW307GD-M4无线梯度土壤三参数监测终端对包气带水动态进行长时序连续监测,并分析考古大棚内水害产生原因及形成机理。结果表明:遗址包气带含水率普遍较高,且大棚外相同层位含水率较棚内高约10%,但土体渗透系数集中于(2.07~3.41)×10^(-5) cm/s,棚外降雨通过水平向渗透对棚内土体作用较弱;潜水位埋深3.2~5.6 m,水文年内变幅约为0.25 m,受其波动影响的上升毛细水,在极端降雨条件下可直接影响发掘界面,是土遗址水害的主控因素。借鉴“上游拦截,下游排泄,本体控制”的工程地质思维调控祭祀区土体含水率,可为土质遗址保存提供新的思路。

Affected by water,ruins of soil texture are prone to crack,crispness,salt accumulation,moss and other hazards,which is not conducive to their preservation.In order to find out the source of soil water damage in the soil site so as to provide a reliable basis for the preservation of this site,based on the refined hydrogeological survey,this paper used the Solinst Levelogger groundwater recorder and MW307GD-M4 wireless gradient soil three-parameter monitoring terminal to continuously monitor the water trend in vadose zone in a long time sequence,and analyse the cause and mechanism of water damage in the archeological shed.The results show that the moisture content of the vadose zone of the ruin is generally high,with that of the same layer outside the shed about 10%higher than that inside the shed,but the soil permeability coefficients mainly range from 2.07×10^(-5) to 3.41×10^(-5) cm/s,suggesting the weak effect of the rainfall outside the shed on the soil in the shed through horizontal infiltration.The phreatic water level ranges from 3.2 to 5.6 m,with an amplitude of about 0.25 m within the hydrological year.The rising capillary water subject to its fluctuation can directly affect the excavation interface under extreme rainfall conditions as the main control factor of the water damage of the ruin of soil texture.By reference to the engineering-geological concept of“upstream flow interception,downstream flow discharge and local flow control”,regulating the moisture content of the soil body in the sacrificial area casts new light on the preservation of ruins of soil texture.