COUPLED P-Y T-Z ANALYSIS OF SINGLE PILES IN COHESIONLESS SOIL UNDER VERTICAL AND/OR HORIZONTAL GROUND MOTION

Various approaches are currently used for the analysis of piles under vertical and lateral loading. Among these, the beam-on-a-nonlinear Winkler foundation (BNWF) approach using published P-y, T-z and Q-z curves is widely used in practice. In this approach, the P-y and T-z responses are generally uncoupled from each other. The objective of this paper is to investigate the influence that the coupling of the P-y and T-z responses has.on the cyclic and dynamic response of piles in cohesionless soil. A cyclic model is first developed and a parametric study is conducted to investigate the effect the initial confining pressure, angle of wall friction and effective vertical stiffness have on the lateral cyclic hysteretic response. A dynamic model is then developed, and used to study the response of a single pile in cohesionless soil under horizontal and/or vertical ground motion. Results from the parametric study showed that the three parameters did not have a significant influence on the lateral cyclic hysteretic response. Under horizontal and/or vertical ground motion, the horizontal ground motion was observed to dominate the inertial interaction response, and significantly affected both the horizontal and vertical displacement response, mainly due to second-order P-Δ and gapping effects.     

A palynological and geoarchaeological investigation into Bronze Age farming at Belderg Beg,Co. Mayo,Ireland

This contribution describes the results and interpretations of geoarchaeological and palynological analyses of a soil profile near to a ¹⁴C dated Bronze Age roundhouse in a sub-peat field system at Belderg Beg, north Mayo in western Ireland, which displayed field-scale evidence of tillage in the form of cultivation ridges. This evidence of arable cultivation was supported by the presence of quernstones in the roundhouse, but there was no supporting evidence from other forms of socio-economic analysis. Soil micromorphological analysis was employed to define how the ridges were created and with what tools; pollen analysis was used to characterise the surface vegetation and test the purpose of the ridges. The results unequivocally showed that a phase of ard cultivation was followed after a brief hiatus by ridge-and-furrow tillage. There were tentative indications of possible amendment of the earlier, ard-worked soil, and more definitive evidence of midden material addition to the ridged soil. An AMS radiocarbon assay on the base of peat overlying the ridges indicated that tillage occurred in the Mid to Late Bronze Age.     

云冈石窟顶部第四纪土壤覆盖层含水率变化特征及洞窟渗漏水问题探讨

为研究云冈石窟顶部土壤覆盖层的含水率变化情况,建设了土壤环境监测网收集云冈石窟土壤含水率实时监测数据,并分析其时空变化特征及影响因素。结果表明,平坦地形条件下云冈石窟顶部第四纪土壤覆盖层含水率时空变化特征明显:年变化具有周期性,垂向上随深度逐层降低(冬季除外)。春、夏季土壤含水率抬升、储水,秋、冬季下降、失水;在春、夏日土壤含水率呈白天上升、夜晚下降趋势,秋、冬日则呈白天下降、夜晚也下降趋势。土壤含水率时刻处于不停的运动变化之中,受温度、大气降水、微地形等众多因素影响,山体边坡浅层土壤可能为侧向饱和流的入渗通道。降雨对土壤含水率的影响深度与实际入渗深度不一致。云冈窟内顶板及岩壁上部、中部含水率主要受降雨渗透窟顶土壤层、沿岩体裂隙通道进入洞窟的渗漏水控制,而岩壁底部含水率更多受窟前不饱带和与地下毛细水的影响。多年的防水实践也证明云冈洞窟渗漏水主要来自于石窟顶部及附近区域。防渗排水始终是云冈洞窟渗漏水治理的主导思路,建议应根据窟顶土壤厚度、地形地貌和遗址分布等分区治理,充分发挥土壤的防渗作用,减少对土壤覆盖层的过度干预。防渗层材料在具有防渗作用的前提下,应具备一定的透气性,满足“洞窟—覆盖层—大气环境”之间的水汽循环。     

中国古建筑中几种石灰类材料的物理力学特性研究

为探讨适宜于岩土文物保护加固的石灰类材料,对中国古建筑中几种石灰类材料及欧洲水硬石灰的化学组成和物理力学特性进行对比研究。研究表明烧料礓石、烧阿嘎土、欧洲水硬石灰NHL5及改性捶灰的化学组成主要是气硬性胶凝材料石灰CaO(或Ca(OH)2)和水硬性胶凝材料β-硅酸钙(β-CS)及铝硅酸钙(CAS),并且这些材料的结石体具有大的孔隙率及非常小的收缩变形性等特点,适宜于岩土文物的保护加固。除此之外,石灰、糯米灰浆、蛎灰、传统捶灰的主要化学组成为石灰CaO(或Ca(OH)2),实验研究结果显示,浆液的凝固速度慢,弹性波速小且上升速率慢,结石体虽然孔隙率大,但强度在短期内较低,易产生收缩变形,不适宜用于短时间内有强度要求的岩土文物保护加固,所以有必要对蛎灰和传统捶灰做进一步的改性研究,以便更广泛地应用于岩土文物的保护加固中。     

Paleoethnobotany in the Neotropics from Microfossils: New Insights into Ancient Plant Use and Agricultural Origins in the Tropical Forest

Analysis of plant microfossils (phytoliths, pollen, and starch grains) from archaeological and paleoecological sediments in the humid Neotropical forest can provide information on some formerly intractable problems in American paleoethnobotany and archaeology. Each technique has strengths that redress the other's shortcomings, and all three microfossils can be recovered from early sites, securely identified, and dated. Agricultural origins, Pleistocene/ Holocene environmental changes, and the evolution of slash-and-burn agriculture are three important issues that yield substantial results to phytolith, pollen, and starch grain study. Microfossils of a number of domesticates, including maize, manioc, squash, bottle gourd, arrowroot, and leren, have been identified in contexts dating from 9000 to 7000 radiocarbon years B.P. The scope and methodology of traditional paleoethnobotany should be expanded to routinely include microfossil study.     

A review of lessivage and neolithic cultivation in southern England

A critical re-examination is undertaken of a model for soil development which has been put forward to explain the occurrence of buried sols lessivés (Argillic brown earths) under several neolithic earthworks in southern England. The model attributes the formation of sols lessivés to neolithic agricultural activity, and is based on the assumption that lessivage will not occur under woodland, but will be facilitated by clearance and cultivation. A review of the pedological literature shows both these assumptions to be unsubstantiated, and a survey of the sites used in the development of the model reveals that at only one is there any independent evidence for neolithic agriculture. An alternative hypothesis for sol lessivé development is put forward which associates it with the post-glacial forest. The original model was taken as an environmental cause of the change in the neolithic economic base. In view of the arguments presented here this explanation is no longer tenable.     

Cereal pollen grains in pre-elm decline deposits: Implications for the earliest agriculture in Britain and Ireland

Evidence of cereal type pollen grains in the pre-elm decline sections of pollen profiles is demonstrated from five sites in Ireland and three in Britain. Technical and archaeological considerations are also discussed. It is concluded that cereal cultivation in the British Isles occurred before the traditional beginnings of arable activity as denoted by the elm decline, and that the palynological data should be seen to underline caution in referring pre-elm decline pollen changes to Mesolithic disturbance.