塑料套管混凝土桩加固公路软土地基现场试验研究

根据某一高速公路塑料套管混凝土桩加固软土地基工程实例,对桩土应力、地表沉降、横向位移、不同深度孔隙水压力进行观测,讨论了塑料套管混凝土桩桩承式路堤的工作机理。结果表明：塑料套管桩加筋路堤的临界高度约为1.26倍桩净距,观测期末,荷载分担比接近89%;桩帽和桩间土最大差异沉降为30 mm左右,且应力集中比随着差异沉降的增大而线性增大;路堤堤脚附近不同深处横向位移随着路堤填筑高度的增加而增加,施工结束时,地表以下2.5 m处横向位移最大,为12.86 mm;横向位移-沉降比和横向位移增加率随着路堤填筑高度的增加逐步减小并趋于稳定,塑料套管混凝土桩加筋路堤系统能够有效防止路堤横向位移的发展和改善路堤的整体稳定性。     

Investigation report of geotechnical disaster on river area due to typhoon landfall three times on Okhotsk region,Hokkaido, Japan

For one week from August 17 to 23, 2016, three consecutive typhoons made landfall in Hokkaido for the first time on record. These typhoons and the front they stimulated brought record-breaking torrential rain over the eastern part of Hokkaido. To investigate the damage to grounds and rivers resulting from this rainfall, the Japan Society of Civil Engineers (JSCE) and the Japanese Geotechnical Society (JGS) formed a disaster research group to conduct an investigation. This report provides the results of the investigation into damage to the grounds of areas along the Tokoro River of the Okhotsk region, Hokkaido, that suffered from this tremendous and diverse disaster. Specifically, the report describes the situation of the levees which were broken and eroded by the overflowing water, the shape of the levee bodies, the levee body soil properties examined by observation of the sections, as well as the occurrence of sand boiling and air blows. The washout of road embankments as well as damage to road bridge mounting fills and abutment backfills were also investigated. The investigation has demonstrated the need to clarify the resistance of the abutment backfills and levee bodies to flowing water as well as the geotechnical predominant factors in order to clarify the mechanisms behind erosion and washout, the need to review new measures that allow for the scale of sand boiling and resultant changes in levee body stability, and the fact that the existing embankments were able to temporarily suppress the flooding water which had spilled over from the river. Furthermore, although it has been identified that the findings of a study on an embankment washout associated with a tsunami can be applied to measures taken against the overflowing water, it has also been found necessary to clarify the predominant geotechnical factors using model tests and to use a more sophisticated analytical approach to establish a geotechnical stability review as soon as possible in order to prevent the levees and embankments from being eroded and washed out due to overflowing water.     

桩承式路堤土拱数值模拟中路堤土本构模型的选择

数值模拟方法已成为研究桩承式路堤中土拱最重要的手段,其关键在于路堤填土要采用合理的本构模型。建立桩承式路堤平面土拱分析的弹塑性有限元模型,考虑摩尔-库伦模型（MC）、硬化土模型（HS）和小应变硬化土模型（HSS）3种不同的路堤土本构模型,用有限元方法模拟不同路堤土本构模型下桩承式路堤中的土拱形态和土拱效应。计算结果表明：3种不同路堤土本构模型下平面土拱的形态都是半个椭圆。路堤土采用HS和HSS模型,获得的土拱形态、效应和桩帽-土差异沉降相同。较之HS和HSS模型,路堤土采用MC模型时计算得到的桩帽-土差异沉降较小,桩帽荷载分担比略大。当路堤高度较小时,采用MC模型获得的土拱远小于HS和HSS模型下的计算结果。土拱效应的数值模拟中路堤土可采用简单的MC模型,但土拱形态的数值模拟中路堤土宜采用HS模型。     

爆震条件下淤积砂基础的抗液化安全评价

三峡二期高土石围堰座落在极易液化的新淤积砂基础上，故在基坑钻爆开挖过程所诱发的爆破震动作用下对该淤积砂基础进行抗液化安全评价极具工程意义。本文利用爆震条件下一期围堰淤积砂基础中动孔隙水压力实测资料，结合二期围堰的静力有限元计算成果，设法对二期围堰淤积砂基础是否液化作出科学的评估。     

路堤下粉喷桩复合地基的工作性能与设计方法

研讨粉喷桩及粉喷桩复合地基的工作性能与设计方法，包括：桩的工作状态、桩身应力、变形及桩侧摩阻力的分布与变化、桩的强度破坏，临界桩长与加强桩段；路堤下粉喷桩复合地基中校及桩间土的工作特征，桩间土的强度发挥，天然地基土承载力折减系数与桩土应力比；设计途径，设计参数或指标的取值，设计调整的原则与方法，沉降计算等内容。     

南京扬-巴区外道路软基处理及防护设计

介绍了扬-巴区外道路部分路段的设计,针对高填方路堤软土层厚度大且分布不均匀,易造成施工期路基失稳及沉降过大或不均匀沉降,高陡土质边坡易遭受雨水侵蚀破坏等工程问题,设计采用了砂垫层、塑料排水板、粉喷桩、换填土、垫隔土工布等综合措施进行软基处理并结合相应的道路排水、边坡防护措施,使该道路在施工期及运行期均未发生路堤失稳及工后沉降过大、边坡冲刷等不良现象。     

填方高度及填土土质对高填方路基沉降影响分析

以湖南省境内的常张与衡枣高速公路沉降观测资料为依据,分析研究了不同填方高度、不同填土土质对高路堤沉降的影响,其中主要通过对不同填方高度下几个典型观测点的沉降资料和对7种不同填土的路基沉降资料的整理,探讨了不同影响因素下的高填方路基沉降变形特性.     

南宁市防洪堤江北西堤主要工程地质问题分析评价

该文通过对江北西堤工程地质条件及堤基土的物理力学性质的分析,对堤防的抗滑稳定、渗透及渗透稳定性、岸坡稳定性进行了评价,由此得出结论:所用的勘察手段、评价方法合理、恰当,取得了较好的工程效果,为类似工程提供借鉴并具指导意义。     

土工结构应力、变形的弹粘塑性有限元分析

根据土工结构的结构特点、施工过程及可能的运行情况,基于弹粘塑性势理论开发研制了相应的有限元计算程序。作为算例,应用该程序分析研究了广州珠江堤防改造工程在几种主要工况下的变形及应力状态,对其稳定性进行了讨论,并提出了建议。     

探地雷达在填石路堤的压实质量检测中的应用

在简述探地雷达基本原理以及测试方法的基础上,介绍探地雷达在填石路堤施工压实质量检测中的应用.