EXPERIMENTAL STUDY ON BEARING CAPACITY AND SETTLEMENT OF COARSE SAND AFFECTED BY CHANGES OF GROUNDWATER LEVEL

Along with the development of city underground space, the place where buried depth of underground water is low, like Shenyang, dewatering is needed during construction and water level is recovered after completion. Frequent water level change can lead to many geotechnical problems such as bearing capacity change, surface collapse caused by additional settlement of foundation and seepage flow in soil. Especially the bearing capacity and the additional settlement are key problems. Many researches and papers only supply the qualitative results. The purpose of this paper is to get the quantitative results. This paper is based on the model test. It builds a foundation model on the coarse sand, through the SLT test, monitoring the water level and the stress change using the soil pressure sensor and water pressure sensor, and recording the bearing capacity, settlement and stress change along with the water level change. Then conducted numerical analysis, and used fitting formula to settle the relationship of model test and numerical analysis. The results show that the coarse foundation base characteristic value can lose 26% in max after the water level change. If load is applied on the foundation either the water level up or down can cause additional settlement. If the water level rises 4.3m, the additional settlement can be 0.565mm(caused by bearing capacity drop). If the water level drops 4.3m, the additional settlement can be 0.315mm(caused by the increase of effective stress). Numerical analysis shows that for dry sand the numerical analysis fit well. For saturated sand, the tolerance can be fixed by the fitting formula.