Field study on the behavior of pre-bored grouted planted pile with enlarged grout base

This paper presents the results of field tests performed to investigate the compressive bearing capacity of pre-bored grouted planted (PGP) pile with enlarged grout base focusing on its base bearing capacity. The bi-directional O-cell load test was conducted to evaluate the behavior of full scale PGP piles. The test results show that the pile head displacements needed to fully mobilize the shaft resistance were 5.9% and 6.4% D (D is pile diameter), respectively, of two test piles, owing to the large elastic shortening of pile shaft. Furthermore, the results demonstrated that the PHC nodular pile base and grout body at the enlarged base could act as a unit in the loading process, and the enlarged grout base could effectively promote the base bearing capacity of PGP pile through increasing the base area. The normalized base resistances (unit base resistance/average cone base resistance) of two test piles were 0.17 and 0.19, respectively, when the base displacement reached 5% D_b (D_b is pile base diameter). The permeation of grout into the silty sand layer under pile base increased the elastic modulus of silty sand, which could help to decrease pile head displacement under working load.

     

Pore structure and heterogeneity of shale gas reservoirs and its effect on gas storage capacity in the Qiongzhusi Formation

Fine characterization of pore systems and heterogeneity of shale reservoirs are significant contents of shale gas reservoir physical property research.The research on micro-control factors of low productivity in the Qiongzhusi Formation(Fm.)is still controversial.The lower Cambrian Qiongzhusi Fm.in the Qujing,Yunnan was taken as the object to investigate the influence of mineral compositions on the phys-ical properties of the reservoir and the heterogeneity of shale,using the algorithm to improve the char-acterization ability of Atomic Force Microscopy(AFM).The results showed that:(1)The pores are mainly wedge-shaped pores and V-shaped pores.The pore diameter of the main pore segment ranges from 5 to 10 nm.Mesopores are mainly developed in the Qiongzhusi Fm.shale in Well QD1,with the average pore diameter of 6.08 nm.(2)Microscopic pore structure and shale surface properties show strong hetero-geneity,which complicates the micro-migration of shale gas and increases the difficulty of identifying high-quality reservoirs.(3)The increase of clay mineral content intensifies the compaction and then destroys the pores.Conversely,brittle minerals can protect pores.The support and protection of brittle minerals to pores space depend on their content,mechanical properties and diagenesis.(4)Compression damage to pores,large microscopic roughness and surface fluctuations and strong pore structure heterogeneity are the reasons for the poor gas storage capacity of the Qiongzhusi Fm.,which will lead to poor productivity in the Qiongzhusi Fm.     

岩溶在古地理研究中的作用——“关于古地理研究中若干原则问题的商榷”一文的补充及讨论

本文从现代、地史时期岩溶剥蚀速度及岩溶铝土矿的形成等方面探讨岩溶在古地理研究中的重大作用,从而提出稳定地区“缺失”某一时期地层,并非该时期为陆;而是前期仍有沉积,后期才真正上升为陆,遭受剥蚀。     

小尺度地形阻塞作用的数值试验

本文采用数值试验方法,讨论了一个高度只有200m的小尺度地形的阻塞作用,表明当大气低层的平均风速和温度层结使得Froude数小于1时,就有可能在地形的上风向形成阻塞。本文共试验了一般稳定层结、深厚逆温和浅薄逆温几种情况,讨论了数值结果和Froude数判别式之间的差异和原因,并计算了阻塞发生时的浓度分布。     

关于中国大陆五级以上地震的时间间隔问题

本文研究了我国大陆地区五级以上地震的时间间隔分布情况,发现我国大陆M_S≥5.0地震的时间间隔ΔT与其频次N_(ΔT)之间存在以下关系式:lgN_(ΔT)=2.14-0.15·ΔT本文还讨论了我国大陆出现长期无五级以上地震后,是否将有七级地震的问题。     

粉煤灰碎石混凝土灌注桩法加固软弱地基效果的分析与检验

对由深厚软弱土层组成的地基,采用粉煤灰碎石混凝土灌注桩法予以加固处理时,其施工机具相对简单,工期短,节约“三材”,投资省,具有显著的经济效益。由粉煤灰碎石混凝土灌注桩和深厚软弱土层共同构成的复合地基的工程特性,介于一般碎石桩复合地基与混凝土桩桩基之间,其基本特征是:承载力的提高,主要是置于深厚软弱土层中的粉煤灰碎石混凝土灌注桩的排水和垂直加筋作用的结果;其承载机理,部分具有一般碎石桩复合地基的特征;在结构物荷载作用下,其桩、土荷载分担特征,比较接近于普通混凝土桩桩基。     

Growth Dynamics of the Middle Devonian Jukoupu Bioherm,Xinshao, Hunan

The growth process, palaeoecological features and the function of organisms in reef-building of the Jukoupu bioherm in Hunan are discussed in detail. The bioherm is divided into 10 microfacies. Organisms are very abundant in the reef. Thirty-two genera Belonging to 7 phyla have been recognized. They make up 5 communities composed mainly of stromatopoids, Corals and algae, each of which has its own salient ecological features. An analysis of all communities shows that the organic functions are very complex. The same organisms may possess diverse functions simultaneously as the reef growth enters the late stage. The growth process of the reef may involve five stages' (l)biostrome stage, (2) stabilization stage, (3) frame-type reef-building stage, (4) binding and covering-type reef-building stage, and (5) baffle- type reef -building stage.     

矿物分类和识别的人工神经网络模型

本文提出矿物分类和识别的人工神经网络模型，并选取一组标样－我国沉积碳酸盐型锰矿中菱锰矿作为研究对象，识别效率达１００％。结果表明，该模型性能良好，可望成为矿物识别的有效手段。     

小莱河麻粒岩相铁建造的矿物组合—变质过程p、T变化的探讨

小莱河太古宙麻粒岩相铁建造的矿物组合有：①斜方辉石（Fs87）＋钙铁辉石＋石英＋磁铁矿±莱河矿；②铁闪石＋铁浅闪石质角闪石＋石英＋磁铁矿＋碳酸盐±Fe－镁川石（云辉闪石）。辉石的出溶显示了它形成的不同阶段：片晶发育的OpxⅡ－CpxⅡ是最后稳定产物，计算的平衡温度是742℃，按相图获得的压力是7×108～7．8×108Pa；钙铁辉石中“001”片晶是易变辉石片晶转变的，Opx－Cpx－Pig（片晶）阶段据相图推测可能形成于近820℃，8×108Pa的条件下。原始均一相的OpxⅠ－CpxⅠ阶段矿物成分按估算的片晶含量计算，它们的形成温度接近820℃，可能的压力范围是11×108～13×108Pa。由此得到ITD型麻粒岩相p－T－t轨迹。莱河矿无氧化成因的证据，认为它是在麻粒岩相条件下生成的。云辉闪石的Si—O链重复周期是3×，其Fe／（Fe＋Mg）＝0．85，是接近富铁端元的Fe－镁川石，它与闪石一起在640到近700℃条件下交代了辉石。     

玻璃钢作地面沉降监测标体的可行性研究

玻璃钢具有质量轻、强度高、耐腐蚀等特性,可作为达到特定工程目的的成型材料。本文通过论证,认为在地面沉降监测工程中为了更准确灵敏地反映地下岩土的变形,选用轻质高强度的玻璃钢作引测标体是可行的。此外,由于玻璃钢成本低,因此,还可使中小城市开展地面沉降监测时减少基础性投入。