关于长江漫滩地区存在的粉质粘土夹粉土、粉砂地层浅析

长江漫滩地区由于其形成机理原因,经常存在粉质粘土夹粉土或粉砂层的情况,其夹层情况及土层含水性质与基坑降水密切相关,基坑工程地下水的处理是关键工作。如果能准确掌握夹层的分布情况及其含水层性质情况,对基坑设计工作具有重要的工程意义。本文以长江漫滩地区临近四个基坑工程做例,介绍了各工程地勘资料中对该层土的描述及场地水文地质情况,阐述了工程设计情况及降水井与该层土的相对关系,结合现场实际施工情况及出现的一些险情问题,对险情的原因进行了分析并总结,可为类似的工程提供一些借鉴。

复合地基中粉喷桩桩长的选用

主要以河南郑州地区粉土和较软弱粉质粘土互层的地基为例,论述了进行多层建筑时设计粉喷桩中桩长的选 用方法。

深厚粘土层上坝体设计

本文简要阐述了在库区存在大量透水性较差覆盖层,可以利用当地粉土及粉质粘土修筑坝体及水平铺盖;并利用水平防渗取代悬挂式垂直防渗的措施及利用下游设置排水减压井来减少坝体及坝基渗漏对下游的浸没影响。

武汉市深厚互层土某超深大基坑的几点思考

武汉长江Ⅰ级阶地分布深厚粉质粘土与粉土、粉砂互层土;该层土对基坑有较大影响,本文以武汉航运中心大厦超深大基坑为例,该基坑采用钢筋混凝土地下连续墙+四道双圆环内支撑进行支护,TRD水泥土搅拌墙落底止水帷幕,水力冲挖节约大量工期。针对该基坑施工开挖过程出现的一些问题进行探讨,为武汉地区类似场地基坑提供经验及借鉴。

Lateral displacement of silty clay under cement-fly ash-gravel pile-supported embankments: Analytical consideration and field evidence

Based on back analysis of lateral displacements measured in situ by using the analytical solution, a useful method for estimating stress concentration ratio of geosynthetic-reinforced and pile-supported(GRPS) embankments was proposed. In order to validate the proposed method, a full-scale high-speed railway embankment(HSRE) with four instrumented subsections over medium compressibility silty clay was constructed in three stages. The soil profile, construction procedure and monitoring of settlements and lateral displacements of the four test sections were described. The field deformation analysis results show that 1) the combined reinforcement of CFG piles and geosynthetic layer perform well in terms of reducing lateral displacements; 2) the development of lateral displacements lags behind the increase of fill load, which can be attributed to the vertical load transfer mechanism of the pile foundation; and 3) pile length has a dominant effect on the stress distribution proportion between piles and surrounding soils. The comparison between predicted and experimental results suggests that the proposed analytical solution and the back analysis-based method are capable of reasonably estimating the lateral deformation and the stress concentration ratio, respectively, if the appropriate soil elastic modulus is chosen.

鄱阳湖组(第四系)的修订及特征

根据对鄱阳湖地区 Zk0 1钻孔柱状剖面的研究 ,对鄱阳湖组的定义进行修订、补充 ,认为鄱阳湖组为一套以青灰色淤泥质粘土、黄褐色粘土、粉质粉土为主夹少量粉砂或细砂的湖泊—河口三角洲相沉积。年代地层为第四系全新统 ,底界年龄约 6 2 10± 12 5 a B.P.,开阔湖泊沉积始于 32 4 0± 180 a B.P.,且由北向南时代渐新 。