Analytical solution for upheaval buckling of shallow buried pipelines in inclined cohesionless soil

Upheaval buckling of pipelines can occur under thermal expansion and differential ground settlement.Research on this phenomenon has usually assumed the pipes are buried in horizontal ground.For long-distance transmission pipelines across mountainous areas,the ground surface is commonly inclined.Based on the Rankine earth pressure theory and Mohr-Coulomb failure criterion,analytical formulae for calculating the peak uplift resistance and the slip surface angles for a buried pipe in inclined ground are presented in this paper.Analyses indicate that the slip surfaces in inclined ground are asymmetric and rotate towards the downhill side.Under a shallow burial depth,the failure plane angle is highly impacted by the ground inclination.When the embedment ratio(H/D)is more than 4,the influence of the ground slope on the failure plane angle is negligible.The peak uplift resistance reduces in inclined ground,especially when H/D is less than 1.Finally,a simple equation considering the impact of ground inclination is proposed to predict the peak uplift resistance.

土体含水率时域反射法现场测试经验模型研究（英文）

目的:建立含水率与介电常数间的经验关系模型是利用时域反射(TDR)技术测试土体含水率的关键。通过收集并建立包含45种土样418个试验数据点的数据库,提出一个土体质量含水率与表观介电常数间的经验公式,分析经验公式误差随土体类型、干密度、击实功、孔隙水电导率和温度等因素的变化规律,并提出考虑干密度影响的修正方法。创新点:1.基于电磁波相互作用理论,直接建立土体质量含水率和介电常数间的关系模型;2.通过数据拟合得到通用型经验公式,可在现场无标定快速高效地实现含水率测试。方法:1.通过理论分析,直接建立土体质量含水率和介电常数间的关系模型(公式(9));2.通过试验数据收集和回归分析得到通用型经验公式(图2和公式(10));3.通过影响因素分析,对公式的适用性和有效性进行分析(图3~7)。结论:1.该经验公式对常见的土体类型均能给出误差在±0.05 g/g以内的结果;2.在1.3~2.3 g/cm3的干密度范围内,该经验公式具有较好的适用性;在工程中常见的击实功和孔隙水电导率变化范围内,含水率测试精度可满足工程要求;4~30°C温度变化范围对本经验公式的计算结果无明显影响;3.利用该经验公式,对于特殊场地,可以不通过标定实现TDR现场测试,具有较好的实用性。

Analytical solution for 1D consolidation of unsaturated soil with mixed boundary condition

Based on consolidation equations proposed for unsaturated soil, an analytical solution for 1D consolidation of an unsaturated single-layer soil with nonhomogeneous mixed boundary condition is developed. The mixed boundary condition can be used for special applications, such as tests occur in laboratory. The analytical solution is obtained by assuming all material parameters remain constant during consolidation. In the derivation of the analytical solution, the nonhomogeneous boundary condition is first transformed into a homogeneous boundary condition. Then, the eigenfunction and eigenvalue are derived according to the consolidation equations and the new boundary condition. Finally, using the method of undetermined coefficients and the orthogonal relation of the eigenfunction, the analytical solution for the new boundary condition is obtained. The present method is applicable to various types of boundary conditions. Several numerical examples are provided to investigate the consolidation behavior of an unsaturated single-layer soil with mixed boundary condition.

P波斜入射形成的动应力路径及影响因素分析（英文）

目的:研究P波斜入射下的地基动应力路径,探讨其影响因素和可能变化范围,为进一步研究斜入射地震波作用下场地动力响应奠定理论基础。创新点:1.从数学上证明斜入射P波在任一深度的地基中形成的应力路径在剪应力分量(偏差正应力-水平剪应力)组成的平面中为一个斜椭圆;2.分析了P波入射角、土体泊松比和单位波长深度对斜椭圆应力路径形状与大小的影响。方法:1.基于半无限弹性空间的地震波传播理论,考虑地震波在自由界面的反射,推导土体中任一深度处由P波斜入射产生的动应力,并表示成由剪应力分量组成的平面下的应力路径(公式(9))及该应力路径的特征参数表达式(公式(A12)^(A14));2.通过控制变量法,分析参数敏感性(图7、9、10和12)。结论:1.虽然证实P波斜入射引起的应力路径为斜椭圆形式,但在地基深度、入射波频率和波速的特定组合下,斜椭圆仍可从斜线一直变化到圆形,形式较为多样化;2.P波斜入射角度在30?~60?时引起的动偏应力幅最大,最大可达同等条件下其它入射角产生的动应力幅的2倍以上;3.斜入射角大于45?后,斜椭圆路径形状几乎不随入射角改变,在研究范围内以竖直扁椭圆形为主;4.土体饱和度大于70%时,泊松比的变化对土体斜椭圆路径形状影响不大,但动应力幅随泊松比增大而显著降低。