共查询到18条相似文献,搜索用时 859 毫秒
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杨东东 《中国新技术新产品》2024,(4):102-104
孔压静力触探技术对土体的扰动较小,因此广泛应用于工程地质勘察。本文以某工程场地为研究对象,采用孔压静力触探对地质情况及其土层分布规律进行勘测,得出以下结论 :通过孔隙水压力、锥尖阻力和孔压比3种土层分类指标可直观判断土层的分布规律,通过其曲线变化趋势可分析不同地层间的差异。地块1的3种土体分类指标较大,说明土体以黏土为主,地块2的3种土体分类指标较小,说明土体以砂土为主。地块3的土体分类指标曲线变化趋势存在明显的突变点,当深度小于18m时,锥尖阻力曲线变化趋势波动性较大,而孔隙水压力与孔压比曲线变化趋势较为平缓,当深度超过18m时,锥尖阻力曲线的变化趋势较为平缓,而孔隙水压力与孔压比曲线的波动性较大,说明该地块在18m处存在土层界面。 相似文献
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《噪声与振动控制》2020,(3)
本文基于Biot理论,首次提出更符合软土地区的列车-轨道-准饱和地基的2.5维有限元理论。在验证本文程序的可靠性后,计算分析高铁荷载作用下车速对准饱和分层地基环境振动的位移、孔隙水压力和衰减规律的影响,对比准饱和与饱和地基的振动差异性。结果表明:当车速小于表层土体瑞利波速时,准饱和地基的环境振动位移时程曲线在轨道中心和远离轨道处均能观察到明显的列车轮轨分布,衰减曲线平滑,衰减较快;当车速大于表层土瑞利波速时,远离轨道的位移时程曲线变的模糊,衰减曲线具有波动性,衰减速率减缓。地表以下0.5 m处超孔孔隙水压力最大,车速250 km/h~350 km/h时超孔隙水压力随深度的衰减规律相似,当车速进一步提高到400 km/h时超孔压衰减曲线不再光滑,有较多折点。准饱和地基振动的竖向位移峰值大于饱和地基,而超孔隙压则相反。 相似文献
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假定沉桩过程是一个平面应变圆孔扩张问题, 采用了修正剑桥模型, 给出了软粘土中沉桩过程后初始时刻超孔隙水压力沿桩径分布的解析函数, 并与Cao 等人的数值解以及Gibson 提出的公式进行了比较。根据土骨架的弹性位移特性以及水流的连续性条件, 得到了桩周土体固结的控制方程。运用分离变量法并结合边界条件以及初始条件得到了桩周土中超孔隙水压力消散的级数解答, 该解答可以作为孔压静力触探反求固结系数的一个理论依据。通过2 个算例分析了土体的应力历史以及刚度对桩侧超静孔压消散的影响;算例分析表明, 随着超固结比的增大, 归一化后的塑性区半径以及桩侧超孔隙水压力均在减小;桩侧的超静孔压消散前期较快, 后期较慢。 相似文献
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混凝土衬砌既有粘弹性性质,又有渗透性。实际工程中内水压力值由衬砌和孔隙水共同承担,该文通过引入与孔隙流体体积分数有关的应力系数合理地分配了衬砌和孔隙水分别承担的内水压力值。根据衬砌和土体界面处衬砌中流体速度和土体中流体速度相等以及应力和位移连续性条件建立了部分透水边界条件。将衬砌和土体分别视为多孔粘弹性材料和液固两相介质,采用饱和多孔介质理论和粘弹性理论,在频率域内给出了内水压力作用下粘弹性饱和土-衬砌相互作用时饱和粘弹性土位移、应力和孔压和衬砌的位移和应力解析表达式。进行了参数研究,表明:应力系数以及衬砌和土体相对渗透系数对系统动力响应影响很大。另外,应力系数合理地确定了边界衬砌和孔隙水分别承担的内水压力值。 相似文献
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为研究实际海洋环境中随机性波浪作用下弹塑性海床饱和土体真实的动力学行为及振动液化过程演化规律,该文结合Biot动力固结理论和本课题组提出的砂土震动液化大变形本构理论模型和处理液化时零有效应力状态的数值算法,采用JONSWAP频谱来模拟波浪,给出了随机波浪作用下饱和砂质海床土体中超静孔隙水压力瞬态变化与液化过程的弹塑性动力分析方法。该方法可很好地描述在随机波浪作用下,海床土体内超静孔隙水压力场在时空上呈现出的瞬态起伏变化和平均单调累积增长或消散的特性以及海床内达到零有效应力的液化状态在时间域上间歇性出现、在空间域上连续性移动的规律性。 相似文献
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《工程力学》2016,(12)
采用能够考虑原状土体实际K_0固结特性弹塑性本构模型的屈服面方程为屈服准则,根据柱孔扩张基本平衡方程和相似解方法,对处于天然状态下的饱和土体柱孔扩张问题进行求解,推导出从零初始孔径柱孔扩张问题在小应变情况下塑性区的有效应力、超静孔隙水压力半解析解答。同时,通过算例对比分析表明:饱和土体在柱孔扩张后其塑性区超静孔隙水压力沿径向呈衰减趋势变化,其大小随着超固结比的增大而增大,孔壁周围土体有效应力下降明显,随着超固结比的增大,有效应力的减小趋势有所降低;考虑K_0固结影响的本文解答所得到的超静孔隙水压力大于修正剑桥模型的解答,扩孔完成后其周围土体有效应力下降大于后者。 相似文献
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压密注浆机理研究及效果检验分析 总被引:1,自引:0,他引:1
本文就压密注浆的影响范围,超孔隙水压力的分布规律,土体强度的增长规律以及压密注浆中的地层抬高效应进行了研究,并对软土地基注浆技术的效果检验方法进行了分析,提出了一些有意义的建议。 相似文献
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ABSTRACT The soil permeability of marine sediments varies with burial soil depth because of consolidation under overburden pressure. However, most previous investigations available for water wave-seabed interaction problem have simply assumed seabed with uniform permeability. This paper proposes an analytical solution to investigate the short-crested wave-induced soil response in a porous seabed with variable permeability. The pore pressure and effective stresses generated by a three-dimensional short-crested wave system are obtained from a set of equations incorporating a variable permeability. The numerical results indicate that the effect of variable permeability on the wave- induced soil response is significant. 相似文献
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波浪作用下粘弹性海床动力响应的数值分析 总被引:2,自引:0,他引:2
基于广义Biot理论,采用Kelvin-Voigt模型描述海床土骨架的应力应变时间的本构关系,从Galerkin加权余量法出发建立以土骨架位移u和孔隙流体全位移U表达的u~U形式的有限元边值方程,采用Newmark逐步积分法求解时域内动力方程。数值计算表明土骨架和孔隙流体的加速度对粘弹性海床动力响应的影响极小。当土的粘滞系数的数值小于其弹性剪切模量的大小时,体粘滞系数和偏粘滞系数的变化对超静孔压幅值的影响较小,但对有效应力幅值的影响相对显著。对于粘滞系数较大的海床,波浪荷载可能导致其变形在很短的时间内单调迅速增长至破坏。 相似文献
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3D models for wave-induced pore pressures near breakwater heads 总被引:1,自引:0,他引:1
Wave-induced pore pressure is one of the important factors in the analysis of foundation stability around coastal structures. Existing models for the wave-induced seabed response around breakwater heads have been limited to poro-elastic soil behavior and de-coupled oscillatory and residual mechanisms for the rise in excess pore water pressure. To overcome the shortcoming of the existing models, in this study a new three-dimensional poro-elastoplastic model is established, in which both oscillatory and residual mechanisms can be simulated simultaneously. The reduced cases of the proposed model are verified with existing 2D experimental data available and a 3D poro-elastic analytical solution in front of a breakwater. With the proposed new model, a parametric study is conducted to investigate the relative differences of the predictions of the wave-induced pore pressure and liquefaction with poro-elastic and poro-elasto-plastic models. Based on numerical examples, it can be concluded that relative differences between elastic and elasto-plastic models are significantly affected by wave periods and water depths. Wave height significantly affects the development of residual pore pressure versus time. Plastic soil behavior plays an important role in a seabed of low permeability. Plastic soil behavior has more significant influence on wave-induced residual pore pressure than the amplitude of the oscillating pore pressure. Furthermore, poro-elastic analysis tends to under-estimate the size of the liquefaction regions around breakwater heads. 相似文献
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变参数土层一维固结的半解析解 总被引:1,自引:0,他引:1
基于直接模态摄动法方法,提出了变参数土层一维固结方程的半解析解。该方法利用均匀土层一维固结方程的特征值和固有函数,将变参数土层的固结微分方程转化为代数方程,从而得到变参数土层的特征值和固有函数,计算结果具有两阶以上精度。在此基础上进一步导出了超孔隙水压力和沉降随时间变化的计算公式。该文建议的方法对土层性质的变化规律没有特殊要求,不仅适用于层状土层,也适用于土介质物理特性沿深度不均匀变化的土层,从而为各类变参数土层的一维固结分析提供一种有效的计算手段。通过算例,表明这一方法简单实用,且具有良好的精度。 相似文献
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航行舰船在海底岩土层中引起的弹性波被称为舰船地震波,主要由舰船低频辐射噪声引起,可用于识别舰船目标。将舰船地震波简化为液固多层半无限空间低频点声源引起的地震波动问题,基于波数积分方法,通过FFP数值积分得到了海底表面声压、位移和加速度的频率特性曲线,分析了不同浅海环境对点声源海底地震波的波动特征的影响。结果表明:软质海底竖直方向加速度具有明显的低频通过特征,点声源海底地震波频域特征具有方向性;接收横距、岩土层吸收衰减系数和软硬程度、水深、沉积层厚度等均对点声源海底地震波的波动特征具有影响。 相似文献
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This paper addresses the problem of one-dimensional solidification of concentrated mixtures of solid particles in a Newtonian host fluid. This problem has ramifications in the fields of sedimentation and filtration, and is presently studied in the context of restabilization of liquefied cohesionless soils. Solidification is described in terms of a wave phenomenon, and its propagation and structure are modeled in terms of conservation of mass and momentum principles and the necessary constitutive relations for closure. Relative motion between the two species as well as variations in volume concentration of the granular material are taken into account. The solution yields the distributions of the solids stress, solids concentration, pore pressure and component velocities below the solidified interface. The thickness of the shock over which these adjust from their liquefied to their solidified values is found to be sensitive to the particulate material properties. On the basis of this study it is suggested that measuring the local pore pressure gradient in a cohesionless soil yields more useful information on the state of the soil than commonly used single pore pressure transducers. It is further shown that controlled laboratory experiments on solidification wave propagation can be used as a practical way of determining the properties of the particulate material. 相似文献