共查询到20条相似文献,搜索用时 15 毫秒
1.
本文主要介绍:在近期海相沉积的软粘土层上,采用砂垫和砂井结合(即混合砂地基),上部结构施工前不进行堆载预压的办法,修建多层砖房的设计和施工。1979年夏动工,1981年冬竣工交付使用,近三年来使用情况良好,未发现异常变形,达到预期效果,施工简便,经济效果显著,是砂井排水固结处理软粘土地基,应用在房屋建筑上成功的一例。 相似文献
2.
结合新长铁路二期工程的施工实践,介绍采用袋装砂井、砂垫层、土工格栅综合加固软土地基的原理、施工工艺、质量检查以及几点体会。 相似文献
3.
Iman Hosseinpour Marcio S. S. Almeida Mario Riccio Magnos Baroni 《Geotechnical and Geological Engineering》2017,35(3):1051-1066
The compressibility properties, undrained shear strength, and stress history are essential for reliable calculations of settlement and bearing capacity of soft soils. However, it is sometimes a challenge to determine representative parameters for very soft and high plasticity clays, which are often found in Brazilian coastal areas. In this study an extensive site investigation was planned aiming to interpret the behaviour of a trial embankment on stabilized soft ground. The site investigation was carried out in a test area located in the west of city of Rio de Janeiro, consisted of three clusters in which standard penetration tests, vane shear tests, and piezocone tests (CPTu) were performed. A number of correlations was developed and compared with empirical equations in order to verify their reliability. The results of these tests made it possible to define geotechnical parameters of the soft clay to use in the numerical and analytical computations of the embankment on reinforced ground. 相似文献
4.
5.
Appropriate evaluation of shear modulus and damping characteristics of soils subjected to dynamic loading is key to accurate
seismic response analysis and soil modeling programs. Dynamic centrifuge experiments were conducted at C-CORE (Memorial University
of Newfoundland) centrifuge center to investigate the dynamic properties and seismic response of soft clay and dry loose sand
strata. Soft clay with shear strength of about 30 kPa and well graded silica sand at about 35% relative density were employed
in a rigid container to simulate local site effects. Several earthquake-like shaking events were applied to the model to evaluate
variation of shear modulus and damping ratio with shear strain amplitude and confining pressure, and to assess their effects
on site response. The estimated modulus reduction and damping ratio were compared to the predictions of empirical formulae
and resonant column tests for both soft clay and loose sand. The evaluated shear modulus and damping ratio were found to be
dependent on confining pressure in both soil types. Modulus variation in both soils agreed well with the empirical curves
and resonant column test results. However, the sand modulus values were slightly higher than the empirical relations and resonant
column tests. This discrepancy is attributed to higher stress and densification of sand during large amplitude shaking applied
to the model. The damping ratio at shear strains lower than 0.5% was in reasonable agreement with the empirical curves and
the resonant column tests in both clay and sand models, but was generally higher at shear strain larger than 0.5%. 相似文献
6.
Hyperfiltration of Nacl Solutions Using a Simulated Clay/Sand Mixture at Low Compaction Pressures 总被引:1,自引:0,他引:1
It is widely recognized that clays and shales can demonstrate membrane properties. When a hydraulic head differential exists
across a membrane-functioning clay-rich barrier, some of the solute is rejected by the membrane. This process is known as
hyperfiltration. Some shallow geologic environments, including aquitards bounding shallow perched aquifers and unconfined
aquifers, some river and stream beds, and some lake bottoms contain clay–soil mixes. Many engineering structures such as landfill
liners, mixed soil augered barriers, and retention pond liners also consist of soil–clay mixes. No previous testing has been
performed to investigate the likelihood that hyperfiltration may occur in such mixed soils. Therefore, we performed five experiments
using different mixes of Na-bentonite and glass beads (100, 50, 25, 12 and 0% clay) to determine if any of these mixes exhibited
membrane properties and to investigate what effect clay content had upon the membrane properties of the soil. Each mixture
was compacted to 345 kPa and the sample mixtures were 0.58–0.97 mm thick. All the experiments used an approximately 35 ppm
Cl− solution under an average 103 kPa hydraulic head. Experimental results show that all the simulated clay–sand mixtures do
exhibit measurable membrane properties under these conditions. Values of the calculated reflection coefficient ranged from
a low of 0.03 for 12% bentonite to 0.19 for 100% bentonite. Solute rejection ranged from 5.2% for 12% clay to a high of over
30% for the 100% clay. The 100% glass bead sample exhibited no membrane properties. 相似文献
7.
8.
动力荷载作用下软粘土的残余变形计算模式 总被引:10,自引:3,他引:10
在试验结果的基础上,提出了动力荷载作用下计算软粘土残余变形的模式。并将计算结果与不排水和部分排水情况下观测到的孔隙水压力及残余应变进行比较,两者具有较好的吻合性。本文所提出的计算模式可用来估算动力荷载(例如地震荷载、交通荷载)作用下建于软粘土地基上的建筑物及其它设施所产生的附加沉降。 相似文献
9.
利用ALI遥感图像进行矿化蚀变信息提取方法探讨 总被引:1,自引:0,他引:1
矿化蚀变信息提取是遥感找矿的重要手段之一。Advanced Land Imager(ALI)遥感图像信噪比高达100~200,且有较高的波谱分辩率,能够区分具有标示性波谱特征的岩矿。以美国Cuprite地区ALI遥感图像为例,通过数字处理、最小噪声分离变换(MNF),分离和均衡数据中的噪声。然后提取纯净像元(PPI),输入到N维可视化器中开发端元组分光谱,并与波谱库中的波谱进行比对分析。将提取的端元作为样本,进行数据集合评估,最后进行蚀变信息的提取。结果表明,ALI遥感数据由于其波段多,波谱空间分辨率高,经过MNF-PPI后的三维散点图端元提取,能够识别更微弱的岩矿信息。 相似文献
10.
在砂井地基固结度计算中,土的固结系数是一个十分重要的参数,土的固结系数通常通过室内试验求得,但室内取得水平向固结系数制样比较困难。利用软基处理过程中孔隙水压力监测资料来推算软土的固结系数,并和室内试验加以对比分析,总结出二者之间的相互关系及变化规律,可供同类工程设计借鉴。 相似文献
11.
12.
ZhangZhenfei HuGuangdao YangMingguo LiuXing WangZhenlmi LiWenhui ZhangXiaobing HeLi 《中国地质大学学报(英文版)》2003,14(3):257-260
Field data of outcrop spectrums provide important basis for modeling of hyper-spectral remote sensing aiming at mineral prospecting. We make an approach to the application of rough set theory in spectral discriminiation of rocks. We build a decision table with an adequate number of samples (out-crops) of known rock type (the universe), of which the conditional atributes are discretized “area spectrum absorption indexes“ (ASAI) corresponding to wavelength intervals, and the decision atribute is rock type. We search to obtain the exhaustive set of reducts of the table, each of which will serve as a variable number of deduction rules. Suppose we have n (usually a very big number) rules in total and there are m types of rocks in our universe, for any unknown sample, we judge its rock type by each of those rules. An unknown sample may be recognized as a different type by different rules because it is out-side our universe, and we accept the most frequent judgment result and ignore the other m-1 types of results. Our ASAI is an improvement upon the traditional spectrum absorption index (SAI), better applicable to field spectrums: given a spectrum curve and a wavelength interval, we take the average reflectance within the interval as a base line and let ASAI=αbelow/(αabove αbelow), where αbelow and αabove stand for total areas, bounded by the curve, the base line and the borders of the intervalbelow and above the base line respectively. With the equipments of FieldSpectr Fr (made by ASD Co., US), we collected data from Baiya gold deposit, Yunnan, and applied the above method to discriminate altered rocks as an experiment. The results show satisfactory performance of the method. 相似文献
13.
14.
油井射流排砂泵扩散管出口流场分析 总被引:1,自引:0,他引:1
依据RNG-ε双方程湍流模型,建立油井射流排砂泵固液两相流方程;在此基础上,应用CFD计算机分析软件,对比分析了扩散管出口突变结构和渐变结构的射流排砂泵的效率、固相比、速度场分布、压力场分布。数值分析结果表明:射流泵扩散管出口采用渐变结构,可以有效减少固液两相流的逆向速度矢量,是提高射流排砂泵综合性能的有效手段。 相似文献
15.
在实验分析的基础上,提出了一种新的求取碎屑岩储层中粘土总量的方法---二级抽提分离+非定向X射线衍射法,即首先用传统的抽提分离法分别提取出粒径小于10μm和10~64μm的微粒,然后用粒径小于10μm微粒的质量加上利用非定向X射线法测出的粒径在10~64μm微粒中粘土部分的质量,就得到该样品中粘土总量。并以WN油田碎屑岩储层为例,具体论述了该法的计算过程及其实际应用效果。研究结果表明,该法具有原理简单、精度高、理论性强、实际应用效果良好的优点,可作为求取沉积岩储层中粘土总量的可靠方法。 相似文献
16.
四氯化碳重液法分离蒙脱石 总被引:2,自引:1,他引:1
提出了一种新的蒙脱石重液分离方法,蒙脱石在正辛胺水溶液中浸过后,密度降至1.60×103kg/m3以下,可用CCl4作重液实现与其它粘土矿物及杂质的分离。用7.5mol/LNaOH溶液处理此含有正辛胺的蒙脱石,可得纯度很高的钠蒙脱石。用此法进行蒙脱石定量分析,所得结果与国际铸造协会推荐的溴仿酒精重液法相符合,且成本低、操作方便、污染小。 相似文献
17.
Ads Abdelaziz Shariful Islam Md Iskander Magued 《Geotechnical and Geological Engineering》2021,39(8):5529-5547
Geotechnical and Geological Engineering - Reliable prediction of surface and subsurface settlements induced by shallow tunnels is important to minimize the adverse effects which may take... 相似文献
18.
The deformation mechanism of engineered municipal construction waste (EMCW) is complicated and different from that of the traditional soil. A series of field tests and field measurements were performed on the piled mountain project to investigate the deformation characteristics of EMCW during the construction waste accumulation. Experimental studies revealed that EMCW was defined as a kind of heterogeneous soil with well-graded soil. The coefficients of uniformity were all greater than 10, while the coefficients of curvature were between 1 and 3. The permeability had approximately the same performance as the sandy gravel did. The field test results showed EMCW had the characteristics of small deformation and the time effect of loading. The p–s curves indicated that the bearing capacity of construction waste improved after 1 year’s filling. These phenomena were mostly caused by the complexity, diversity, and inhomogeneity of EMCW. According to the proposed control standards of settlement and lateral deformation, as a method of foundation treatment, EMCW was an effective way to build a large piled mountain on soft soil foundation. 相似文献
19.
20.
为改良上海粘土的强度和变形特性,分别采用棕榈和麦秸秆加筋,以提高土的强度和抗变形性能。试验以质量加筋率和加筋长度作为影响因素,分析比较两种加筋土的无侧限抗压强度。试验结果为:(1)棕榈加筋土的无侧限抗压强度高于麦秸秆加筋土,两种加筋土均高于素土。(2)棕榈的适宜加筋条件为:质量加筋率1.0%,加筋长度的平均值15mm;四分之一圆管状麦秸秆的适宜加筋条件为:质量加筋率0.3%~0.4%,加筋长度15mm。(3)棕榈加筋土的应力应变曲线表现为应变强化型,麦秸秆加筋土的应力应变曲线表现为应变软化型。初步试验结果表明,棕榈与麦秸秆均适宜作上海地区粘土的加筋材料,加筋效果棕榈优于麦秸秆。 相似文献