基于有效固结力模型的河道堤防加固技术

在众多基础设施建设中,河道堤防工程对确保水利工程项目稳定运转具有重要左右。本文提出了基于有效固结力模型的河道堤防加固技术,旨在提高河道堤防工程的稳定性和安全性。针对有效预应力模型的不足,构建有效固结力模型的理论方程并进行原理性分析。针对河道堤防基土加固问题,提出强化桩配合分层分块换填砂的地方加固措施。在河道堤防加固试验中,证实了有效固结力模型优于有效预应力模型,其基土固结度为45%时,可以确保河道堤防的安全。

不同固结力下的煤粉流动特性

采用JENIKE剪切实验方法对相同粒径的两种不同水分含量的煤粉进行了一系列剪切实验,获得了煤粉的流动函数和其他流动特性参数.研究结果表明,煤粉的剪切力、压实密度、黏聚力和流动函数都随着固结力的增大而增大;固结力为50,kPa时,煤粉的内摩擦角出现最小值;在30,kPa和130,kPa的固结态下,含水率为7.0%的煤粉压实密度比含水率为4.1%的煤粉大,但其黏聚力比含水率为4.1%的煤粉小;在50,kPa、70,kPa和100,kPa固结态下则有相反情况.

毛巾织物毛圈固结力影响因素的研究

在毛巾织物的机械物理性能中,毛圈的固结性能是比较重要的,也是比较实用的。本文通过自己改装的仪器,对毛巾试样(同一组织、同一原料但不同规格)的毛圈固结特性进行测试分析,提出了毛巾织物结构参数对毛圈固结力影响的多元回归方程,结果表明:①依靠电子计算机技术,用主成分分析及回归方法能够较好地求得毛圈固结力与多个结构参数的数学模型;②固结力的测试方法是正确的,在对固结力的影响因素中,经纬纱密度;地经纱和纬纱的捻系数是主要的因素。如果经纬炒的密度、捻系数等确定后,可通过计算得到它们对毛圈固结力的贡献;③在设计毛巾织物时,可根据得到数学模型,综合考虑固结力与其它性能,确定最合适的结构参数。

动静力排水固结法在淤泥质地基处理工程中的应用

以广州南沙泰山石化仓储区1期淤泥质地基处理工程为背景,介绍了采用动静力排水固结法处理促淤饱和软黏土地基的基本思想和工艺。该工程施工与现场实时监测相结合,利用孔隙水压力、土体分层沉降和载荷试验等检测指标对加固效果进行了监测和检测。工程实践表明,采取动力即低能量"少击多遍"的强夯施工工艺,辅以填土预压和设置竖向塑料排水板的静力方法来加固淤泥质地基,其效果明显,促淤地基的物理力学性能和抗变形性能显著提高,整体加固效果很好,工后各项指标完全达到或超过预期值。

动静力排水固结法加固淤泥地基的技术及效果

目的对广州某工程采用的动静力排水固结法处理淤泥地基的加固技术及加固效果进行研究,以期找到合理的动力工序、参数及排水系统的设置.方法通过实时监测超孔隙水压力、土体分层沉降等指标的结果,原位测试静载荷、十字板剪切、静力触探等的结果,对比加固前后土体物理力学性质指标的结果,检验加固效果;对于深厚淤泥地基加固,采用少击多遍、逐层加固的施工工艺并辅助良好的排水系统.结果油罐区和道路区工后承载力特征值分别达到120 kPa和180 kPa,加固前后淤泥的平均含水量、孔隙比及压缩系数分别降低了26.1%、31.6%和45.2%,密度、黏聚力和内摩擦角分别提高11.3%、27.2%和47.1%.结论静动力排水固结法的成功应用不但降低了成本,也为东南沿海地区类似的软土地基处理工程提供了经验.

动力排水固结加固淤泥地基的关键技术研究

为了保证广州南沙泰山石化一期淤泥地基处理工程的质量,采用现场试样的方法,对动力排水固结法处理淤泥土地基的关键技术—动力工序和排水系统的设置进行了研究。结果表明,对深厚淤泥地基,水力吹填粉细砂作为强夯垫层时,在设置合理的竖向和水平排水系统的基础上,宜采用低能量"少击多遍,逐层加固"的动力施工工艺,每遍点夯的夯击能量应控制在1000(kN·m)内。加固后的土体物理力学指标均有一定程度的改善,整体加固效果很好。该成果对类似的软土地基处理工程有一定的借鉴和指导意义。

静力排水固结法在软土路基处理中的应用研究

介绍了4种静力排水固结法在深厚软土路基处理中的应用,通过不同软土路基处理方式验证软土地基处治效果。从施工原理、施工环境、原始地貌等方面进行对比,分析施工过程中软土地基的沉降速率、位移速率、孔压变化速率,利用原位试验分别剖析不同的静力排水固结方法对软土物理力学性质的改良状况,提出最适合横琴地区的静力排水固结方法。

动静力排水固结法处理淤泥地基的现场试验研究

结合广州南沙港淤泥地基处理工程,利用超孔隙水压力、分层沉降和抗剪强度等指标,对动静力排水固结法加固淤泥地基的加固深度和加固效果进行现场试验研究。结果表明,增加总夯击能可明显地增大有效加固深度;夯击能一定时,夯击四遍或五遍,每遍点夯的夯击能控制在900 kN.m以下时,加固效果和加固深度均优于夯击三遍,重锤低落距夯击方式的加固深度和加固效果优于轻锤高落距。

静力排水固结法在软土路基处理中的应用研究

近年来,静力排水固结法在软土路基处理中的应用问题得到了业内的广泛关注,研究其相关课题有着重要意义。本文首先对静力排水固结法相关内容做了概述,结合实际案例研究了动静力排水固件法在软土路基处理中的应用,并结合相关实践经验,就其施工效果的检测和评价展开了研究,阐述了个人对此的几点看法与认识,望有助于相关工作的实践。

浅析软土地基静力排水固结处理法的应用

文章以某市新建市政道路为研究案例,详细分析了软土地基中静荷载排水固结施工技术的处理成效,并就最终的加固效果进行分析。

饱和地基的初始沉降与孔隙水压力

从 Biot固结方程获得半无限线弹性地基在垂直向集中荷载作用下的初始时刻解 ,由此得到任意分布荷载作用下的初始沉降和孔压分布 ,且结果非常简洁。

A coupled strain softening and hardening model for completely weathered granite in a fault zone

his study focused on exploring the specificity of mechanical behavior for completely weathered granite,as a special soil,by consolidated drained triaxial tests.The influences of dry density(1.60,1.70,1.80 and 1.90 g/cm^(3)),confining pressure(100,200,400 and 600 kPa),and moisture content(13.0%,that is,natural moisture content)were investigated in the present work.A newly developed Duncan-Chang model was established based on the experimental data and Duncan-Chang model.The influence of each parameter on the type of the proposed model curve was also evaluated.The experimental results revealed that with varying dry density and confining pressure,the deviatoric stress–strain curves have diversified characteristics including strain-softening,strain-stabilization and strain-hardening.Under high confining pressure condition,specimens with different densities all showed strain-hardening characteristic.Whereas at the low confining pressure levels,specimens with higher densities gradually transform into softening characteristics.Except for individual compression shear failure,the deformation modes of the specimens all showed swelling deformation,and all the damaged specimens maintained good integrity.Through comparing the experiment results,the strain-softening or strain-hardening behavior of CWG specimens could be predicted following the proposed model with high accuracy.Additionally,the proposed model can accurately characterize the key mechanical indicators,such as tangent modulus,peak value and residual strength,which is simple to implement and depends on fewer parameters.

树脂结合剂金刚石磨粒把持固结行为分析

深入讨论了磨粒形状、固化温度以及磨粒出刃高度对其在树脂基体中把持固结行为的量化影响,揭示了单颗金刚石磨粒在固结磨料磨具树脂基体中的预受力状态。实验结果表明,在磨粒-树脂固化过程中,同等粒径磨粒中形貌特征为正八面体时磨粒受基体固结把持力最大,正二十面体的固结把持力最小,且最小把持力约为同等条件下最大把持力的十分之一;在树脂的固化温度范围内,当磨粒固化温度按5℃的变化量递减时,固结把持力则按2%的变化量减小;磨粒固结把持力随磨粒出刃高度增大而减小,当磨粒形状为十二面体时二者之间近似存在二次关系。

Use of piezocone tests to predict consolidation yield stress and overconsolidation ratio of lagoonal deposit soil

Existing empirical methods for interpreting the consolidation yield stress and the overconsolidation ratio （OCR） in clays from piezocone tests are briefly reviewed. It can be seen that no universal correlation exists for all worldwide sites. However, for a given clay deposit, there does exist a most appropriate method to reflect the consolidation yield stress and the OCR based on piezocone test data. Three empirical methods are compared based on the piezocone test data collected on Lixia River lagoonal deposit soil sites in the north of Jiangsu province. The objective of this study is to evaluate the validity of the existing relationships linking the consolidation yield stress to piezocone test data and identify the appropriate method for Lixia River lagoonal deposit soil. It is shown that the correlation based on the net tip resistance has much higher accuracy for estimating the consolidation yield stress of lagoonal deposit soil than other methods.

Effect of consolidation parameters on mechanical properties of Cu-based bulk amorphous alloy consolidated by hot pressing

Cu50Zr40Ti10 bulk amorphous alloys were fabricated by hot pressing gas-atomized Cu50Zr40Ti10 amorphous powder under different consolidation conditions without vacuum and inert gas protection. The consolidation conditions of the Cu50Zr40Ti10 amorphous powder were investigated based on an L9（34） orthogonal design. The compression strength and strain limit of the Cu50Zr40Ti10 bulk amorphous alloys can reach up to 1090.4 MPa and 11.9 %, respectively. The consolidation pressure significantly influences the strain limit and compression strength of the compact. But the mechanical properties are not significantly influenced by the consolidation temperature. In addition, the preforming pressure significantly influences not the compression strength but the strain limit. The optimum consolidation condition for the Cu50Zr40Ti10 amorphous powder is first precompacted under the pressure of 150 MPa, and then consolidated under the pressure of 450 MPa and the temperature of 380 °C.

Numerical analysis of crack generation within embankment built on expansive soil foundation

In order to analyze the initial cracking behavior of highway embankment in the regions of expansive soil, the changes in peaks of tensile stress and their location on top of the embankment for a typical highway embankment section were simulated by ABAQUS. The simulation results indicate that the matric suction was a concave distribution on top of the expansive soil foundation and that it induced differential deformation of foundation and embankment. The peaks of tensile stress on top of the embankment are not located at a fixed site, but gradually move towards the shoulder following the evaporation duration. When the evaporation intensity is larger, the peak of tensile stress on top of embankment increases at a faster rate following the evaporation duration,and its location is closer to the shoulder. The thicker expansive soil layer helps the peaks of tensile stress to reach the critical tensile stress quickly, but the embankment cannot crack when the expansive soil layer is no more than 1.5m after 30d soil surface evaporation; the higher the embankment, the smaller the peak of tensile stress occurring on top of the highway embankment, and its location will be further away from the shoulder. Therefore, a higher embankment constructed on a thinner expansive soil layer can reduce the crack generation within the highway embankment.

Mathematical Model Analysis of Quasi Preconsolidation Soft Clay

Soft clay may cause quasi preconsolidation effect under the constant hydrostatic pressure after some time. The result of drained triaxial test represents the effective stress yield surface, which can be described by simple binary linear fabric model. Therefore the pore pressure and deformation of clay can be decided. It also can be used to resolve the real boundary problems with finite element method.

Effect of spark plasma sintering temperature on microstructure and mechanical properties of melt-spun TiAl alloys

A TiAl alloy from pulverized rapidly solidified ribbons with the composition of Ti-46Al-2Cr-4Nb-0.3Y（mole fraction,%） was processed by spark plasma sintering（SPS）.The effects of sintering temperature on the microstructure and mechanical properties were studied.The results show that the microstructure and phase constitution vary with sintering temperature.Sintering the milled powders at 1200 ℃ produces fully dense compact.Higher sintering temperature does not improve the densification evidently.The dominant phases are γ and α2 in the bulk alloys sintered at 1200 ℃.With higher sintering temperature,the fraction of α2 phase decreases and the microstructure changes from equiaxed near γ grain to near lamellar structure,together with a slight coarsening.The bulk alloy sintered at 1260 ℃ with refined and homogeneous near lamellar structure reveals the best overall mechanical properties.The compressional fracture stress and compression ratio are 2984 MPa and 41.5%,respectively,at room temperature.The tensile fracture stress and ductility are 527.5 MPa and 5.9%,respectively,at 800 ℃.

广州南沙某软土地基处理工程信息化施工与分析

为了保证广州南沙某工程动静力排水固结法处理软土地基的质量及进度,在施工的同时对孔隙水压力、土体分层沉降、十字板抗剪强度、静力触探等指标进行了实时监测和分析。通过实施信息化施工,进行施工质量的过程控制与处理场地的点控制,工程整体加固效果良好,工后各项指标完全达到或超过预期值。

Characteristics and Causes of the Preconsolidation Stress of Soils in the Yellow River Delta

Preconsolidation stress （ σP） is the maximum effective stress that a soil has suffered throughout its life. From a geotech- nical point of view, pre-consolidation stress has great importance because it separates elastic and reversible deformations from inelastic and only partially irreversible deformations and marks the starting point of high compressibility. In this study we calculated the preconsolidation stress for 72 undisturbed soil samples from the Yellow River Delta, using the oedometer test and applying the method proposed by Casagrande. The results showed that the over-consolidation ratio （OCR-the ratio of pre-consolidation stress to current natural overburden stress） values of the soil from soil surface to 6m depth varied from 1.72 to 15.34 and the maximum pre- consolidation stress was above 200 kPa. In consequence, the soils of the Yellow River Delta are highly over-consolidated within the upper 6m, the OCR decreasing gradually with depth from 6 to 12m. For samples from deeper than 12m the soils were found to be under-consolidated, which was proved by standard penetration tests （SPTs）. The main causes of this type of consolidation are the mineral composition and the designability of the soil body.