地下水位上升和降雨对桩-网软弱地基变形特性影响研究

Research on the Influence of Rising Water Table and Rainfall Effect on the Pile-net Deformation Characteristics of Soft Ground

基于非饱和土力学理论,结合Bishop非饱和土强度公式,研究路基在地下水水位上升和不同降雨时长条件下变形特性,利用Midas GTS有限元软件,以某路基为例进行研究。结果表明:堆载预压情况下路基垫层顶部沉降小,垫层底部沉降大,地基易产生空洞现象,并随水位降低,加剧空洞效应;土工格栅兜提效应减少沉降12%左右;地下水位变化对路基总体沉降影响较小;降雨初期桩网地基表面会发生大幅度沉降,3 h路基表面沉降可占降雨影响总沉降的70%,3 h降雨桩端刺入量可达到稳定刺入量的84%,24 h是路基表面沉降与桩端刺入量速率明显分界点。

Based on the theory of unsaturated soil mechanics,combining with the Bishop strength formula of unsaturated soil,research of subgrade settlement features under the conditions of the rising water level and different rainfall time was carried out,a subgrade was taken as an example,by using the finite element software Midas GTS. Results show that there is small settlement on the top of subgrade bedding under the case of stack preloading,and due to large settlement on the bottom of subgrade bedding,it will come into being cavitation which will be exacerbated because of the lowing of the water level. The pull effect of geogrid can reduce settlement about 12%. The change of the groundwater level has less effect on total settlement of subgrade bedding. The surface of pile-net subgrade bedding has sharp settlement in the initial rainwater stage,the surface settlement of subgrade bedding will get 70% in three hours by the effect of rainwater,and penetrating quantity of pile foot can reach 84% stable penetrating quantity,twenty-four hours is obvious demarcation point between the surface settlement of subgrade bedding and the rate of penetrating quantity of pile foot.