加卸载条件下吸力对黄土变形特性影响的试验研究

发布时间：2018-01-13 23:28

本文关键词：加卸载条件下吸力对黄土变形特性影响的试验研究　出处：《岩土工程学报》2017年04期 　论文类型：期刊论文

【摘要】：为了探讨基质吸力和净围压对黄土的变形强度及卸载再加载模量的影响,用非饱和土三轴仪对原状Q_3黄土及其重塑土共做了3组27个试验,即9个控制吸力和净围压等于常数的原状Q_3黄土的三轴固结排水剪切试验、9个原状Q_3黄土和9个重塑Q_3黄土的控制吸力和净围压等于常数的三轴固结排水卸载再加载剪切试验。研究结果表明:基质吸力和净围压均对试样的强度及变形特性有显著影响;原状Q_3黄土的偏应力应变曲线随净围压的增大从理想弹塑性型演变为硬化型,因其结构性导致偏应力应变曲线的初始阶段存在交叉现象,试样一直处于剪缩状态;重塑试样在净围压较小时由剪缩逐渐变为较强的剪胀,在净围压较大时则只发生剪缩;表观凝聚力、切线杨氏模量和卸载再加载模量均随着吸力的增大而增大;而吸力对有效内摩擦角及参数n(原状Q_3黄土的初始杨氏模量随净围压增大而变化的指数)、n_(ur)(原状Q_3黄土的卸载—再加载模量随净围压增大而变化的指数)和n_(ur)'(重塑Q_3黄土的卸载—再加载模量随净围压增大而变化的指数)的影响很小,皆可视为常数。基于试验研究结果,提出了考虑吸力和净围压影响的表观凝聚力、切线杨氏模量和卸载—再加载模量的修正计算公式,完善了非饱和土的增量非线性模型。
[Abstract]:In order to investigate the effect of matrix suction and net confining pressure on the deformation strength and unloading reloading modulus of loess, 27 tests were conducted on the undisturbed Q3 loess and its remolded soil by unsaturated soil triaxial apparatus. That is, the triaxial consolidation drainage shear tests of 9 undisturbed Qs _ 3 loess with controlled suction and net confining pressure equal to constant. The control suction and net confining pressure of 9 undisturbed Q3 loess and 9 remolded QK3 loess are tested by triaxial consolidation drainage unloading reloading shear test. The results show that: (1) the control suction and net confining pressure are equal to constant. Both matrix suction and net confining pressure have significant effects on the strength and deformation characteristics of the samples. With the increase of net confining pressure, the strain curve of undisturbed Q3 loess evolves from an ideal elastoplastic type to a hardening one. Because of its structure, there is a cross phenomenon in the initial stage of the deformation stress and strain curve. The specimen has always been in the state of shearing shrinkage; When the net confining pressure was small, the remolded specimen gradually changed from shearing shrinkage to stronger shearing expansion, but only shearing shrinkage occurred when the net confining pressure was larger. Apparent cohesion, tangent Young's modulus and unloading reloading modulus all increase with the increase of suction. And the effective internal friction angle and parameter n (the index of the change of initial Young's modulus with the increase of net confining pressure of the original Q3 loess). The index of the unload-reloading modulus of unloaded loess with the increase of net confining pressure. The unload-reloading modulus of remolded Q3 loess has little effect on the index of the change of modulus with the increase of net confining pressure. Based on the experimental results, a modified formula for calculating apparent cohesion, tangent Young's modulus and unloading reloading modulus considering the influence of suction and net confining pressure is proposed. The incremental nonlinear model of unsaturated soil is improved.
【作者单位】：兰州理工大学土木工程学院;后勤工程学院建筑工程系;延安大学土木工程学院;
【基金】：国家自然科学基金项目(11672330,11272353) 陕西省科技统筹创新工程计划项目(2014KTDZ03-01)
【分类号】：TU444
【正文快照】： the unloading-reloading modulus of remoulded Q3 loesschanges with the increase of net confining pressure)areinsignificant and can be regarded as constants,respectively.*通讯作者(E-mail:chenzhenghan47@163.com))and then,the modified formulae for the appare

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