以南水北调中线工程南阳膨胀土为研究对象, 在保持含水率 20% 和干密度 11 7 g / cm3 不变的条件下, 基于磷 尾矿最佳掺量为 71 5% , 分别将 EPS 颗粒、聚丙烯纤维按不同比例掺入膨胀土中进行无荷膨胀率、无侧限抗压强度 和三轴 CU 试验。试验结果表明: EPS 颗粒能有效抑制膨胀土的膨胀性, 但会降低膨胀土的强度和延性, 当掺量不 为 0% 时, 复合改良土应力应变曲线均随围压的增加, 由应变软化型向应变硬化型过渡, 15% 为最佳掺量。进一步 分析发现黏聚力和内摩擦角与掺量均呈线性负相关, 并得到与掺量有关的抗剪强度公式。聚丙烯纤维对复合改良 土抗压强度峰值影响较小, 但能提高其延性和残余强度, 使土体由脆性破坏转变为塑性破坏。最终得到磷尾矿、 EPS 颗粒和聚丙烯纤维最佳掺量分别为 71 5% 、15% 、01 4% 。

The expansive soil in the m iddle ro ute of South2to2North Water Div ersio n Pr oject in Nany ang w as taken as the re2 search object. Under t he conditio n o f keeping moistur e content and dr y density unchang ed at 20% and 11 7 g/ cm3 , respect ively, based on the 7. 5% optimum do sag e o f phosphate tailing s, w e mix ed EPS particles and polypro pylene fibers in different propor2 tions and added them into t he ex pansiv e soil for tests o f unloaded sw elling ratio , unconfined compr essive str eng th, and triax ial CU. The results show ed that EPS part icles can effectiv ely r estrain the ex pansion and shrinkag e o f ex pansiv e soil, but will r educe the str eng th and ductility of the ex pansive soil. With the increase of confining pr essure, the str ess2str ain curv es o f the modified so ils w ith mo re than 0% do sage w ill all incr ease and chang e from strain so ftening ty pe to str ain hardening ty pe, w ith 15% as the best dosage. Further analysis showed that the cohesion and inter nal f rictio n angle ar e both linearly neg ativ ely correlated with the dosag e. A fo rmula of shear str eng th r elated to dosage was obtained. Po lypr opylene fiber has smaller effects on the peak com2 pressiv e str eng th of the composite mo dif ied soil, but it can increase the ductility and r esidual strength o f the latter, so t hat the so il can be transformed fr om brittle failure to plastic failure. After comprehensiv e analy sis, we found the optimum dosag es of phosphorus tailings, EPS particles and po ly pr opylene fibers to be 71 5% , 15% , and 01 4% , respectively .

国家自然科学基金( 41772332)