新型辐射排水板真空预压加固效果

Ground improvement effect of prefabricated radiant drain vacuum preloading method

针对传统真空预压加固时间长、效果差以及难以满足工程实际需求等问题,提出一种新型辐射排水板真空预压方法。首先,结合天津临港传统真空预压试验工程,分析沉降、超孔隙水压力和加固前后十字板剪切强度变化规律;其次,开展传统真空预压现场试验和数值模拟,对比分析平均沉降和不同深度处超孔隙水压力;在此基础上,系统研究竖向排水板间距、横向排水板间距和横向排水板长度3种影响因素对新型辐射排水板真空预压加固效果的影响。研究结果表明:沉降和超孔隙水压力的数值模拟结果和现场监测结果基本吻合,相对误差在10%范围内,证明了参数选取以及建立的数值模型的正确性;与传统真空预压相比,新型辐射排水板加固地基沉降增大14.75%,加固影响区范围增加0.4 m。竖向排水板间距从1.2 m减小至0.8 m,中心沉降增大47.34%,边缘沉降增大20.73%,加固影响区范围增加1.0 m;横向排水板间距从2.0 m减小至0.5 m,沉降增大31.15%,水平位移增大30.05%,加固影响区范围增加0.6 m;横向排水板长度存在临界值,建议当竖向排水板间距为0.8 m,横向排水板间距0.5 m时,最优横向排水板长度为0.3 m;与传统真空预压方法相比,新型辐射排水板真空预压方法能显著提高吹填土地基的加固效果,减小辐射排水板的竖向排水板间距和横向排水板间距可明显提高地基中心沉降、水平位移和加固影响范围。

Aiming at the problems of the conventional vacuum preloading reinforcement,such as long time,poor reinforcement effect and difficulty to meet the actual needs of the project,a novel prefabricated radiant drain vacuum preloading method was proposed.Firstly,combined with the traditional vacuum preloading test project in Lingang of Tianjin,the development of settlement,excess pore water pressure and vane shear strength before and after reinforcement were analyzed.Secondly,the conventional vacuum preloading field test and numerical simulation were carried out.The average settlement and excess pore water pressure at different depths were compared and analyzed.On this basis,the ground treatment effects of three influencing factors on the vacuum preloading were studied,including prefabricated vertical drain(PVD)spacing,prefabricated horizontal drain(PHD)spacing and length of PHD.The results show that the numerical simulation results of settlement and excess pore water pressure are basically consistent with those of the field monitoring,and the relative error is within 10%,which verifies the validity of the numerical model parameters selection and establishment.Compared with the conventional vacuum preloading,the settlement value increases by 14.75%,and the scope of reinforcement influence area is augmented by 0.4 m for prefabricated radiant drain vacuum preloading.With the PVD spacing decreasing from 1.2 m to 0.8 m,the center settlement value increases by 47.34%,the edge settlement value increases by 20.73%,and the scope of reinforcement influence area increases by 1.0 m.With decrease of the PHD spacing from 2.0 m to 0.5 m,the settlement value is intensified by 31.15%,the lateral displacement increases by 30.05%,and the scope of reinforcement influence area increases by 0.6 m.There is a critical value in the length of PHD.It is suggested when PVD spacing is 0.8 m and PHD spacing is 0.5 m,the optimal length of PHD is 0.3 m.Therefore,compared with the conventional vacuum preloading method,the new prefabricated radiant drain vacuum preloading technique can significantly improve the consolidation effect of the dredger fill ground.Reducing the PVD spacing and PHD spacing can significantly improve the center settlement,lateral displacement and scope of reinforcement influence area.