降雨入渗条件下交河故城土质崖体渗流场计算及稳定性分析

Seepage calculation and stability analysis of the soil cliff under rainfall infiltration in Ruins of Jiaohe

交河故城土遗址是国家重点文物保护单位。其周边直立土质崖体的安全稳定性对整个土遗址的保护有着重要的意义。崖体的安全隐患主要在于其顶部存在众多的宽深裂缝,局部崖体顶部甚至出现了较大的临空块体。根据降雨非饱和入渗理论,建立饱和-非饱和降雨入渗模型,并发展了相应的数值模拟技术,详细分析了在一个较为完整降雨入渗过程中土质崖体内部渗流场的分布特征。在此基础上,根据非饱和土强度理论,考虑了降雨过程中土质崖体非饱和区的强度变化及饱和区渗透体积力的影响,选取了一典型剖面,应用强度折减法计算了崖体支护前后的稳定性,并对现有的加固支护措施作了评价。结果表明:所建立的饱和-非饱和降雨入渗模型较好地描述了降雨过程中崖体内部的渗流场分布;降雨过程中崖体的安全系数逐渐减小;在现有加固支护条件下,崖体的整体稳定性较好,但安全裕度略低,建议对崖体局部临空块体采取进一步的加固措施。

Ruins of Jiaohe is a national preservation unit of culture relic. The stability of soil cliff around Ruins of Jiaohe is very significant to preservation of the relic. The primary damage is the existence of many wide deep crannies and some free face blocks on the top,which destroyed the integrality of soil cliff. Based on the saturated-unsaturated rainfall infiltration theory,the finite element method of rainfall infiltration is presented in this paper,as well as,we develop some new numerical technologies. It is applied to calculation of a full rainfall infiltration process,and the results well describe the distribution of seepage field in the soil cliff. Then,we apply the strength reduction method,considering the influence of soil strength variation in unsaturated zone and seepage load in the saturated zone,to the stability and reinforcement analysis of soil cliff around the relic during the rainfall process. It shows that the safety factor of soil cliff decreased due to rainfall infiltration; the reinforcement system has played a relatively satisfied function on the soil cliff,and the further reinforcement on free face blocks on the top of soil cliff is proposed.