一种新型基坑支护结构的力学性能分析

水泥土预应力支护桩墙工法(HCMW工法)是在SMW工法的基础上发展起来的基坑支护新方法,该方法具有抗弯能力好、止水性强、对周围土体扰动小等优点。结合工程实际,从工况力学分析、地表沉降量、抗倾覆稳定性验算、整体稳定性验算、抗隆起稳定性验算等角度对HCMW工法的支护规律和效果进行研究,结果表明:支护结构的水平位移在加撑前后有较明显的变化,从地表到坑底呈现逐渐减小的趋势,由于开挖时土体卸载,导致侧支护土体的压力减小,在开挖范围内向基坑移动导致基坑下部土体位移减小,一般出现在距坑底0～2m的范围;基坑周围整体沉降量和距坑边距离呈抛物线状,基坑的最大沉降量为18mm,发生在距离坑边5.6m的位置;最后,对基坑抗倾覆稳定性、整体稳定性和抗隆起稳定性进行验算,得到其稳定安全系数分别为1.974、1.386和2.793,均大于规范规定的安全系数,满足安全要求,表明HCMW工法具有较好的支护效果。

Analysis of mechanical properties of a new type of foundation pit supporting structures

Based on SMW engineering method, a new HCMW engineering method for foundation supporting was developed, with the advantages of good anti-bending ability, strong watertight sealing, smaller surrounding soil disturbance. Based on the engineering practice, this paper studies the supporting law and effect of HCMW method in the aspects of working condition mechanics analysis, surface settlement, anti-overturning stability, overall stability, heave resistance stability coefficient and so on. The result shows that the horizontal displacement of supporting structure has been significantly changed after bracing, with a gradually decreasing trend from the surface to the bottom of the pit. With the soil''s unloading in the excavation area, collateral supporting soil pressure decreases, resulting in a decrease in the displacement of the soil in the lower part of the foundation pit, which generally occurs between 0 and 2 m from the bottom of the pit. The total settlements around the foundation pit and their distance from pit rim present a parabolic shape. The maximum settlement is 18mm, which occurs 5.6m away from the pit rim; the anti-overturning stability, overall stability and heave resistance stability coefficient of the foundation pit are calculated, the homologous values being 1.974, 1.386 and 2.793, which are all greater than the standard safety factors in the specification and meet the safety requirements, indicating that the HCMW method has a better supporting effect.