黄土窑洞是我国西北地区极具当地特色的居民建筑。为了探究降雨入渗对黄土窑洞水分迁移规律和稳定性的影响,选取延安市郊区某废弃黄土窑洞为研究对象,开展室内试验获得黄土的土水特性和非饱和抗剪强度,采用COMSOL有限元软件建立窑洞模型,分析降雨条件下窑洞的水分迁移规律和稳定性变化,探讨降雨持时、降雨强度和降雨类型等因素对窑洞水分场和稳定性的影响。结果表明:降雨入渗导致窑洞覆土含水率急剧增大,雨水下渗不断在窑拱周围积聚,致使窑洞安全系数不断减小;降雨持时与降雨强度越大,安全系数减小的幅度越大;短时强降雨相比于长时弱降雨对窑洞的深层土体水分分布影响更大,窑洞稳定性在短时间内剧烈下降;窑洞安全系数的变化相比于降雨过程具有滞后性;前锋型降雨作用下窑洞产生的竖向位移最大,窑洞安全系数的降幅也最大,但在降雨结束后后峰型降雨的安全系数反而最小,对窑洞稳定性最为不利。
Loess cave dwellings is a residential building with local characteristics in northwest China. In order to explore the influence of loess rainfall infiltration on the water migration law and stability of cave dwellings, the loess of an abandoned cave dwelling in the suburbs of Yan'an was selected as the research object, and indoor experiments were carried out to obtain the soil-water characteristics and unsaturated shear strength of loess. The COMSOL finite element software was used to establish the cave dwelling model, analyze the water migration law and stability changes of the cave dwelling under rainfall conditions, and explore the effects of factors such as rainfall duration, rainfall intensity and rainfall type on the moisture field and stability of cave dwelling. The results show that: Rainfall infiltration leads to a sharp increase in the water content of the soil covering the cave dwelling, moisture continues to accumulate around and the arch of cave dwelling which result in a continuous decrease in the safety factor of the cave dwelling. The greater the duration and intensity of rainfall, the greater the decrease of safety factor. Compared with long-term weak rainfall, short-term heavy rainfall had a greater impact on the moisture distribution of deep soil in cave dwelling, and the stability of cave dwelling decreased sharply in a short time. The change of safety factor of the cave dwelling lags behind the rainfall process. The vertical displacement generated by the forward type rainfall is the largest, and the decrease in the safety factor of the cave dwelling is also the largest. But the safety factor of the peak rainfall after the rainfall is the smallest, which is the most unfavorable to the stability of the cave dwelling.
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