粉土抗渗强度测定设备和方法研究

粉土是介于砂性土和黏性土之间的一种过渡类型土,工程性质既与砂性土不同又与黏性土有较大区别。针对目前还没有合适的室内实验仪器测试粉土临界水力比降和抗渗强度的现状,从试样极限平衡状态出发,对土体进行受力分析,研制了粉土抗渗强度测定设备,研究的实验方法解决了粉土饱和难问题。设计的变水头装置和透明接水容器,保证了粉土抗渗强度测定的可靠性和准确性。多个渗透容器并联成多套装置,可实现多个样本同时测定。对杭州钱塘江粉土的实验结果表明,粉土的临界水力比降与一般砂土有差异。原状样的抗渗强度比击实样高。铺设土工布抗渗层,将大大提高粉土的抗渗强度。研究结果可为粉土地基渗透破坏的防控提供参考。

On the Apparatus and Measuring Method of Silt Impermeability

Silt is a kind of complex and transition soil between sand and clay whose engineering property is different from them. According to the limit equilibrium analysis of silt sample, a new apparatus was developed for effectively measuring silt critical hydraulic gradient under seepage failure in laboratory test. The changing water level device and the transparent vessel insure the accuracy and dependability of impermeability intensity measuring. Parallel connection multi-containers were used so more samples could be tested simultaneously.Test results of Qiantang River silt in Hangzhou show that the critical hydraulic gradient of the silt differs from that of sandy soil. It also shows that the impermeability of undisturbed soil sample with horizontal bedding is greater then that of the compaction sample, and that impervious layer of geotextile can considerably improve the impermeability of silt. The result provides more understanding of the prevention of silt seepage failure, and may used as an important reference for engineering.