三轴搅拌桩止水帷幕施工技术例析

本文依托某城际轨道交通车站基坑工程实例,阐述了三轴搅拌桩止水帷幕工艺施工要点,对三轴搅拌桩止水帷幕施工技术质量控制措施进行分析。     

三轴深层搅拌桩在深基坑止水帷幕中的应用

根据工程实例,介绍了三轴搅拌桩在深基坑中的应用技术,结合工程的环境条件,简明阐述了三轴搅拌桩的特性,提出了其施工设计方案,并总结了施工操作方法及质量控制要点。     

地铁工程三轴搅拌桩止水帷幕施工质量控制

结合工程案例,从测量放线与导沟开挖,桩机就位、搅拌与注浆、桩身控制等方面阐述了三轴搅拌桩的施工工艺,对施工中的技术要点与注意事项进行了分析,为类似工程的施工提供参考。     

浅析三轴水泥搅拌桩止水帷幕施工工艺及难点

通过具体的案例,阐述了三轴水泥搅拌桩技术要求、施工难点及施工方法。既有效地阻滞了基坑外地下水位下降,保证了周边建筑物的安全,又充分利用三轴水泥搅拌桩改良基坑边坡土体的特性,保证了基坑边坡的安全。该技术对于特定地质及周边条件限制下基坑边坡工程的综合处理,提供了有效的借鉴意义。     

三轴水泥搅拌桩止水帷幕技术在施工中的应用

通过三轴水泥搅拌桩止水帷幕在古城综合楼的具体应用,阐述了止水帷幕技术要求、施工难点及施工方法,总结了一些施工质量的控制要点,经严格控制,取得了良好的施工效果,保证了基坑的安全。     

三轴搅拌桩止水帷幕在深基坑中的应用技术

结合某市轨道交通1号线一期工程地铁车站施工实践,介绍了一种通过以三轴搅拌桩作为止水帷幕,垂直隔断地下水的方法,在厚砂层地质条件下,妥善解决了城市深基坑施工所面临的抽水降压对周边环境影响的问题。     

三轴水泥搅拌桩组合高压旋喷桩形成止水帷幕的应用

本文介绍的工程实例具有一定的特殊性,本工程的基坑支护止水是在基坑开挖至一定程度后发现基坑内出现多处大管涌现象,现场的水文地质情况与原岩土勘察报告存在较大出入的情况下所采取的止水补强措施。本文阐述了将三轴水泥搅拌桩用于深基坑止水,并在局部无法采用三轴水泥搅拌桩处采取高压旋喷桩进行止水两种止水帷幕组合进行截水的应用。两种措施组合形成的止水帷幕完成后止水效果良好并且能够保证基坑支护体系的稳定。     

三轴水泥搅拌桩止水帷幕技术在施工中的运用探讨

随着我国城市化进程的加快,对于地下空间的开发力度也越来越大,深基坑工程数量也越来越多。而三轴水泥搅拌桩止水帷幕技术将软土与水泥强制板和,使得水泥与软土发生一定的反应,这样就形成以堵水泥柱状的加固土体墙,形成一道防止外水内流和内水外流的屏障,解决了深基坑施工所面临的承压水危害和粥面环境保护的难题。本文主要对三轴水泥搅拌桩止水帷幕技术的具体施工。     

Particle breakage in triaxial shear of a coral sand

This paper presents a laboratory experimental study to comprehensively investigate the characteristics of particle breakage using numerous triaxial tests on a coral sand. Coral is a highly crushable granular material which fills the gaps between more crushable and less crushable granular materials. The monotonic tests and cyclic tests were terminated at the designated axial strains and the designated cyclic numbers, respectively. The grain size distributions were measured by sieve analyses of the specimens after the triaxial tests were performed. The relative breakage and relative fractal dimension were used to quantify the particle breakage. The cause of particle breakage that increased with increasing isotropic consolidation stress was shown to be isotropic stress. An almost linear increase in particle breakage in relative breakage was found as axial strain increased, whereas the increase in particle breakage in relative fractal dimension showed upward convexity. More particle breakage occurred in denser samples. During consolidation to the identical mean effective stress, the anisotropic stress state played a bigger role in particle breakage than the isotropic stress state, but during shearing particle breakage occurred more sharply in the triaxial tests with the isotropic consolidation to the higher confining pressure. In the cyclic shearing, the particle breakage in relative breakage and relative fractal dimension increased in upward convexity as the cyclic number increased, but in upward concavity with increasing axial strain. A hyperbolic model was proposed to correlate the relative fractal dimension with the relative breakage for use with both monotonic and cyclic tests. In the monotonic tests, a hyperbolic model was proposed to correlate the particle breakage in relative breakage and relative fractal dimension with the plastic work per unit volume. It is proposed that the loading-mode-induced (i.e., monotonic loading and cyclic loading) different mechanism of particle breakage meant that this model could not be applicable in the cyclic tests. The results suggested that the hyperbolic correlation of the particle breakage in relative fractal dimension and the plastic work per unit volume is the most reliable method of interpreting the energy consumption characteristics of particle breakage. This approach takes the fractal nature of soil into consideration. A microscopic view of particle breakage is also effective for observing the evolution of particle breakage.     

Particle breakage evolution of coral sand using triaxial compression tests

Particle breakage continuously changes the grading of granular materials and has a significant effect on their mechanical behaviors.Revealing the evolution pattern of particle breakage is valuable for development and validation of constitutive models for crushable materials.A series of parallel triaxial compression tests along the same loading paths but stopped at different axial strains were conducted on two coral sands with different particle sizes under drained and undrained conditions.The tested specimens were carefully sieved to investigate the intermediate accumulation of particle breakage during the loading process.The test results showed that under both drained and undrained conditions,particle breakage increases continuously with increasing axial strain but exhibits different accumulating patterns,and higher confining pressures lead to greater particle breakage.Based on the test results,the correlations between particle breakage and the stress state as well as the input energy were examined.The results demonstrated that either the stress state or input energy alone is inadequate for describing the intermediate process of particle breakage evolution.Then,based on experimental observation,a path-dependent model was proposed for particle breakage evolution,which was formulated in an incremental form and reasonably considers the effects of the past breakage history and current stress state on the breakage rate.The path-dependent model successfully reproduced the development of particle breakage during undrained triaxial compression using the parameters calibrated from the drained tests,preliminarily demonstrating its effectiveness for different stress paths.     

珊瑚礁地质条件下水泥土搅拌桩抗渗性能研究

为研究珊瑚礁特殊地质条件下水泥土搅拌桩的抗渗性能,以海南岛某基坑止水工程为背景,通过原状土室内渗透试验与现场取芯试验,获得了膨润土外加剂水泥土的抗渗变化规律。研究表明：①水泥土搅拌桩在珊瑚礁特殊地质条件下的止水工程中具有良好的适用性。②早期水泥对水泥土渗透性的影响大于膨润土,后期由于膨润土的密实效应,膨润土对渗透性能的影响大于水泥,且随着膨润土掺入量的增加,水泥土渗透系数逐渐减小,抗渗能力增强。研究成果对珊瑚礁地质中工程止水具有一定的借鉴意义。     

三轴应力路径下珊瑚砂的颗粒破碎模型

基于不同轴向应变下平行试样的三轴试验结果,分析了珊瑚砂在三轴排水与不排水条件下颗粒破碎随加载的演化过程,探讨了现有的颗粒破碎能量模型和基于应力的Hardin破碎模型的局限性.为了更好地分析颗粒破碎中间发展过程的特征,将引起颗粒破碎的机制分解为压缩和剪切两部分,并分别建立了与之相对应的破碎模型.压缩机制是指在等应力比条件...     

饱和砂性地层盾构法隧道同步注浆配合比研究

盾构法隧道施工中需采用同步注浆措施来减少建筑间隙产生的不利影响,通过试验手段,以胶砂比为出发点,比较了浆液流动性、强度、泌水性以及收缩率的变化特点,系统地研究了同步注浆材料配合比,并结合工程实施过程中的监测数据加以验证,得出了适合饱和砂性地层的同步浆液材料配合比,为今后类似工程提供指导。     

载体桩在郑东新区密实砂土持力层中的试验研究

以某高层建筑的试桩为背景,通过载体桩基础单桩静载荷试验和载体桩复合地基静载荷试验,分别对两种方案承载力计算值和试验值进行了对比,对桩侧摩阻力的影响进行了分析。研究结果表明:载体桩在达到极限荷载时沉降随荷载的变化呈陡降型,载体桩基础和载体桩复合地基在密实砂土持力层中承载力的计算值均偏于保守,两种方案在此地质条件下忽略桩侧摩阻力的贡献同样过于保守,并且建议施工时应注意载体桩桩头的保护。     

土工合成材料加筋砂土三轴试验研究

本文以 5种国产土工合成材料为加筋材料 ,它们分别是针刺无纺土工织物、涤纶纤维经编土工格栅、玻璃纤维土工格栅、聚丙烯双向土工格栅和聚乙烯土工网 ,用三轴试验比较各种土工合成材料对砂土的加筋效果 ,得到一些有益的结论 ,可指导土工合成材料的优选和研究加筋机理 ,同时指出部分国产土工合成材料产品的不足。     

流砂地层隧道施工技术研究

通过对比不同的施工工艺效果,分析各施工技术在隧道超前加固与降水施工中的作用效果,得到了地表止水帷幕(钢筋混凝土)+帷幕内井点降水+地表旋喷桩及袖阀管注浆+CRD法开挖的整套流砂地层隧道施工工艺,并对该方法在实际应用中的施工流程进行了研究。     

深层水泥搅拌桩施工工艺参数研究

为了确保深层水泥土搅拌桩施工质量、方便施工控制,研究了水泥浆输浆量、搅拌头钻进与提升速度、搅拌轴转速、复搅遍数四个施工参数对深层水泥土搅拌法桩身质量的影响,指出了确保成桩质量的关键因素,应综合考虑成桩质量和施工效率对工艺参数进行优化匹配,为今后深层水泥土搅拌桩施工提供了参考。     

岩层地质条件下后注浆材料配比研究

结合后注浆工艺的定义,介绍了注浆材料的主要性质,针对浆液比重、浆液粘度、析水率、凝胶时间、抗压强度等各项指标,进行了注浆材料的配比试验,并对试验数据进行了分析,最终确定了适用于岩层地质条件下的后注浆材料。