高庙子膨润土强度时效性试验研究  

Experimental study on ageing effect on shear strength of Gaomiaozi bentonite

作　　者：孙德安[1] 张乾越 张龙[1] 朱赞成[2] SUN De-an;ZHANG Qian-yue;ZHANG Long;ZHU Zan-cheng(Department of Civil Engineering, Shanghai University, Shanghai 200444, China;School of Civil Engineering and Architecture, Taizhou University, Taizhou, Zhejiang 318000, China)

机构地区：[1]上海大学土木工程系,上海200444 [2]台州学院建筑工程学院,浙江台州318000

出　　处：《岩土力学》2018年第4期1191-1196,共6页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.11672172);台州市科技计划项目(No.1702gy09)~~

摘　　要：本文用试验方法研究了静置时间对不同含水率高庙子钠基(GMZ07)膨润土强度的影响。在保持试样干密度和含水率不变的情况下,将初始含水率为10%、18%和24%(饱和)3组压实试样分别静置0、5、15、30、90 d,之后采用精度较高的直剪仪在400、800和1 600 k Pa垂直压力下进行剪切试验;同时完成了部分试样的压汞试验。结果表明:GMZ07膨润土的剪切强度随静置时间增长而减小;静置前期,强度下降较快;静置时间超过一定天数后,其剪切强度逐渐趋于稳定。根据3种含水率试样的强度包线可得到:随着静置时间增加,饱和试样的内摩擦角略微下降而黏聚力变化不大;含水率10%和18%试样的黏聚力明显变小而内摩擦角几乎不变。根据Alonso等提出的非饱和土有效应力,结合压实膨润土试样的孔径分布,认为集聚体内孔隙增多是非饱和膨润土强度随静置时间而变小的原因。The ageing effect on the shear strength of Gaomiaozi（GMZ07） bentonite with different water contents were investigated in this paper. Water contents of 10%, 18% and 24%（saturated） of compacted bentonite specimens were kept constant during curing periods of 0, 5, 15, 30 and 90 days under constant volume conditions. Then, the shear tests on the aged specimens were performed at vertical pressures of 400, 800 and 1 600 k Pa by using the shear testing apparatus. At the same time, the microstructure features of the aged bentonite specimens were characterized by means of mercury intrusion porosimetry（MIP） test. The test results show that the shear strength of Gaomiaozi bentonite decreases with the ageing time. The shear strength significantly decreases at the early ageing days and then tends to stabilize when the curing time is over certain days. According to the failure envelopes of three specimens with different water contents, the internal friction angles slightly reduce and the cohesion changes little for saturated specimens with the increase in curing time. For the specimens with water contents of 10% and 18%, the cohesion evidently decreases but the friction angles remain almost unchanged. According to the effective stress of unsaturated soils proposed by Alonso et al and the pore-size distribution, it is considered that the increment in the intra-aggregate pore is the reason for the decrease in the shear strength of the unsaturated bentonite with ageing time.

关 键 词：高庙子膨润土 剪切强度 时效性 黏聚力 内摩擦角 

分 类 号：TU443[建筑科学—岩土工程]