摘要
为了解决填方工程中沉降变形准确计算的问题,采用室内试验与理论推导相结合的方法,实现定量描述不同压实度和吸力对重塑黄土力学特性影响规律的目的。首先,以延安新区重塑离石黄土为研究对象,根据不同功能区的压实情况,设计了3种干密度试样;然后,采用非饱和土三轴剪切仪,通过控制不同基质吸力和净围压,设计了一系列三轴剪切试验,研究了基质吸力对不同压实度黄土力学特性的影响规律;最后,在试验规律的基础上,将基质吸力和干密度引入到邓肯-张非线性模型中。结果表明:在实际工况条件下,重塑离石黄土的破坏形态仅表现为应变硬化和理想弹塑性两种形态,采用双曲线能较好地描述其应力应变关系;干密度对非饱和重塑离石黄土的有效黏聚力、有效内摩擦角和吸力摩擦角均有影响,基质吸力对土体强度的影响主要体现在土体的有效黏聚力上,对有效内摩擦角影响不大;吸力摩擦角在研究范围内总是小于有效内摩擦角。根据试验规律分别拟合了基质吸力和初始干密度与非线性模型参数之间的关系曲线,量化分析了两者对模型参数的影响,并将拟合的结果引入到切线弹性模量中,得到了非饱和离石黄土切线弹性模量的计算公式。该研究内容可为黄土地区填方工程的沉降计算提供参考。
In order to accurately calculating the settlement deformation in filling engineering,the influence rules of different compaction degrees and suctions on mechanical properties of remolded loess are quantitatively described by using laboratory test and theoretical derivation.First,taking the remolded Lishi loess in Yan’an New Area as the research object,3 kinds of dry density samples are designed according to the compaction of different functional areas.Then,a series of triaxial shear tests are designed by using unsaturated soil triaxial shearing apparatus to control the suction and net confining pressure of different matrices,and the influence rules of matrix suction on the mechanical properties of the loess with different compaction degrees are studied.Finally,based on the experimental rules,the matrix suction and dry density are introduced into the Duncan-Chang nonlinear model.The result shows that(1)under the actual working condition,the failure patterns of remolded Lishi loess are only strain hardening and ideal elastic-plastic,and the hyperbolic curve can better describe the stress-strain relationship;(2)dry density has influence on the effective cohesion,effective internal friction angle and suction friction angle of unsaturated remolded Lishi loess,the influence of matrix suction on the soil strength is mainly reflected in the effective cohesion of the soil,buy has little influence on the effective internal friction angle;(3)the suction friction angle is always smaller than the effective internal friction angle within the range of study.The relationship curves of matrix suction and initial dry density with nonlinear model parameters are fitted respectively according to test rules,and their influences on model parameters are analyzed quantitatively.The formula for calculating the tangential elastic modulus of unsaturated Lishi loess is obtained by introducing the fitting result into the tangential elastic modulus.This study can provide reference for calculating settlement of filling engineering in loess area.
作者
张渭军
商丽
ZHANG Wei-jun;SHANG Li(Gansu Third Construction Group Co.,Ltd.,Lanzhou Gansu 730050,China;College of architecture and civil engineering,Huanghuai University,Zhumadian Henan 463000,China)
出处
《公路交通科技》
CAS
CSCD
北大核心
2022年第1期30-39,共10页
Journal of Highway and Transportation Research and Development
基金
国家自然科学基金项目(51768039)
河南省高等学校重点科研项目(22B560009,22B560010)。
关键词
道路工程
非线性模型参数
三轴剪切试验
重塑黄土
基质吸力
非饱和土
road engineering
nonlinear model parameter
triaxial shear test
remolded loess
matrix suction
unsaturated soil
